Ten Things Everyone Should Know About Time

By Sean Carroll | September 1, 2011 10:58 am

“Time” is the most used noun in the English language, yet it remains a mystery. We’ve just completed an amazingly intense and rewarding multidisciplinary conference on the nature of time, and my brain is swimming with ideas and new questions. Rather than trying a summary (the talks will be online soon), here’s my stab at a top ten list partly inspired by our discussions: the things everyone should know about time. [Update: all of these are things I think are true, after quite a bit of deliberation. Not everyone agrees, although of course they should.]

1. Time exists. Might as well get this common question out of the way. Of course time exists — otherwise how would we set our alarm clocks? Time organizes the universe into an ordered series of moments, and thank goodness; what a mess it would be if reality were complete different from moment to moment. The real question is whether or not time is fundamental, or perhaps emergent. We used to think that “temperature” was a basic category of nature, but now we know it emerges from the motion of atoms. When it comes to whether time is fundamental, the answer is: nobody knows. My bet is “yes,” but we’ll need to understand quantum gravity much better before we can say for sure.

2. The past and future are equally real. This isn’t completely accepted, but it should be. Intuitively we think that the “now” is real, while the past is fixed and in the books, and the future hasn’t yet occurred. But physics teaches us something remarkable: every event in the past and future is implicit in the current moment. This is hard to see in our everyday lives, since we’re nowhere close to knowing everything about the universe at any moment, nor will we ever be — but the equations don’t lie. As Einstein put it, “It appears therefore more natural to think of physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence.”

3. Everyone experiences time differently. This is true at the level of both physics and biology. Within physics, we used to have Sir Isaac Newton’s view of time, which was universal and shared by everyone. But then Einstein came along and explained that how much time elapses for a person depends on how they travel through space (especially near the speed of light) as well as the gravitational field (especially if its near a black hole). From a biological or psychological perspective, the time measured by atomic clocks isn’t as important as the time measured by our internal rhythms and the accumulation of memories. That happens differently depending on who we are and what we are experiencing; there’s a real sense in which time moves more quickly when we’re older.

4. You live in the past. About 80 milliseconds in the past, to be precise. Use one hand to touch your nose, and the other to touch one of your feet, at exactly the same time. You will experience them as simultaneous acts. But that’s mysterious — clearly it takes more time for the signal to travel up your nerves from your feet to your brain than from your nose. The reconciliation is simple: our conscious experience takes time to assemble, and your brain waits for all the relevant input before it experiences the “now.” Experiments have shown that the lag between things happening and us experiencing them is about 80 milliseconds. (Via conference participant David Eagleman.)

5. Your memory isn’t as good as you think. When you remember an event in the past, your brain uses a very similar technique to imagining the future. The process is less like “replaying a video” than “putting on a play from a script.” If the script is wrong for whatever reason, you can have a false memory that is just as vivid as a true one. Eyewitness testimony, it turns out, is one of the least reliable forms of evidence allowed into courtrooms. (Via conference participants Kathleen McDermott and Henry Roediger.)

6. Consciousness depends on manipulating time. Many cognitive abilities are important for consciousness, and we don’t yet have a complete picture. But it’s clear that the ability to manipulate time and possibility is a crucial feature. In contrast to aquatic life, land-based animals, whose vision-based sensory field extends for hundreds of meters, have time to contemplate a variety of actions and pick the best one. The origin of grammar allowed us to talk about such hypothetical futures with each other. Consciousness wouldn’t be possible without the ability to imagine other times. (Via conference participant Malcolm MacIver.)

7. Disorder increases as time passes. At the heart of every difference between the past and future — memory, aging, causality, free will — is the fact that the universe is evolving from order to disorder. Entropy is increasing, as we physicists say. There are more ways to be disorderly (high entropy) than orderly (low entropy), so the increase of entropy seems natural. But to explain the lower entropy of past times we need to go all the way back to the Big Bang. We still haven’t answered the hard questions: why was entropy low near the Big Bang, and how does increasing entropy account for memory and causality and all the rest? (We heard great talks by David Albert and David Wallace, among others.)

8. Complexity comes and goes. Other than creationists, most people have no trouble appreciating the difference between “orderly” (low entropy) and “complex.” Entropy increases, but complexity is ephemeral; it increases and decreases in complex ways, unsurprisingly enough. Part of the “job” of complex structures is to increase entropy, e.g. in the origin of life. But we’re far from having a complete understanding of this crucial phenomenon. (Talks by Mike Russell, Richard Lenski, Raissa D’Souza.)

9. Aging can be reversed. We all grow old, part of the general trend toward growing disorder. But it’s only the universe as a whole that must increase in entropy, not every individual piece of it. (Otherwise it would be impossible to build a refrigerator.) Reversing the arrow of time for living organisms is a technological challenge, not a physical impossibility. And we’re making progress on a few fronts: stem cells, yeast, and even (with caveats) mice and human muscle tissue. As one biologist told me: “You and I won’t live forever. But as for our grandkids, I’m not placing any bets.”

10. A lifespan is a billion heartbeats. Complex organisms die. Sad though it is in individual cases, it’s a necessary part of the bigger picture; life pushes out the old to make way for the new. Remarkably, there exist simple scaling laws relating animal metabolism to body mass. Larger animals live longer; but they also metabolize slower, as manifested in slower heart rates. These effects cancel out, so that animals from shrews to blue whales have lifespans with just about equal number of heartbeats — about one and a half billion, if you simply must be precise. In that very real sense, all animal species experience “the same amount of time.” At least, until we master #9 and become immortal. (Amazing talk by Geoffrey West.)

CATEGORIZED UNDER: Science, Time, Top Posts
  • Mike

    I’ve always liked this quote about time:

    “The universe may be timeless, but if you imagine breaking it into pieces, some of the pieces can serve as clocks for the others. Time emerges from timelessness. We perceive time because we are, by our very nature, one of those pieces.” — Craig Callender


    Are the talks going to go on-line any time soon?

  • http://stancarey.wordpress.com/ Stan

    Time organizes the universe into an ordered series of moments

    Or as Ray Cummings pithily put it, in The Girl in the Golden Atom, time is “what keeps everything from happening at once.”

  • Ajay

    Sean Carroll, You are out there.

  • RM Zulkipli

    Then its a day, and the holy sun emerged to roll back the mists..

  • Steffen

    On #9: Also our grandkids won’t live forever. Perhaps they will enjoy a prolonged lifespan and much higher quality of life in old age, but they will not live forever.

    There is a very good reason evolution invented death. The cycle of life and death ensures that a species adapts much better to changing circumstances. Imagine a society where everybody is immortal. It quite inevitably culminates in an ultra-conservative nightmare, where “everything is like it was forever”. Imagine a society where the industry tycoons of the 19th century still own the majority of money and influence.

    A static society must break down sooner or later, one of the best examples for this is the late Soviet Union, where nothing new happened and which was completely dominated by old men who still evaluated everything in terms of an economy based on heavy industry. And when society breaks down (what it does regularly in human history, this is inevitable), most people will then lose the access to this life-prolonging technology.

    I am glad that death exists, and when my time arrives, I will go, to make place for the young generation. They deserve their chance.

  • Drew

    Couldn’t time be emergent from motion? If all motion stopped, what would “time” be? Then again, it seems a chicken/egg scenario. For motion you need space. But time is just another dimension…

  • Rick

    “Then its a day, and the holy sun emerged to roll back the mists..”

    Very pretty, but I would hope that folks with a religious bent don’t take a post focusing on science and time on another long and ultimately unresolvable discussion about God, etc.

    I know it’s a free country and all, but please at least wait until Sean puts up another post more directly addressing the issues you care about — he has a history of doing that.

    Let folks who care about this explore it without having to search through dozens of relatively unrelated comments.

    Not my blog of course, just a request.

  • Alphacarey

    “A lifespan is a billion heartbeats” is true for mammals other than humans. We typically reach a billion heartbeats sometime around our mid-twenties; roughly 3 billion heartbeats for a life span of 75 to 80 years.

  • Howard

    Agree with Drew. If there is no motion there is no temperature. Heat death means no entropy and no way to measure time. Doesn’t time cease to exist at that point?

    Additionally could maximum entropy and minimum entropy be identical? Would that be an explanation to why entropy was low at the big bang?

  • Kevin C

    I’ve always (since about the age of 15) defined Time as “the length of space in which it takes to do something.”

    In a nutshell, if you take a “thing” that has absolutely no motion/activity/action/etc. Even the electrons in the atoms that make it up are not moving, does time exist for it? The (theoretical answer) is “No”, because if nothing happens, then it has no way of measuring that anything has changed, and if nothing changes, there is no (subjective) time.

    To an outside observer, time would have passed….but if there are no outside observers then all is encompassed within a non-active state, and therefore there is nothing to compare the difference in location to…thus, nothing happened, including the passage of time.

    Just my thoughts…which to this day (25+ years) still makes sense to me. :)


  • Shane


  • http://fqxi.org/community/forum/topic/949 master of paradox

    ” The past and future are equally real” – in a classical deterministic universe, and just maybe if the many worlds idea is true, but no. An “emitter” produces a wavefunction that expands out and then either a collapse occurs or else you believe all of the absorptions really happen (which, despite beggiing off, really does violate conservation laws.) Can you really imagine that running backwards, toward that single emitting point?

  • http://faculty.luther.edu/~macdonal Alan Macdonald

    “Every event in the past and future is implicit in the current moment.”

    How about an atomic bomb going off or not according as a radioactive atom decays or not.
    (Many worlds is only speculative.)

  • alyxandr

    “every event in the past and future is implicit in the current moment” — My impression was that the Determinists hadn’t won the argument *quite* yet… surely, while people are still arguing about how to interpret wavefunction collapse, there’s still room for some randomness?

  • boreds

    (2) “every event in the past and future is implicit in the current moment”

    What about the quantum fluctuations which ‘freeze in’ to become the cosmological large-scale structure we see today? Isn’t this structure thought to be truly random, with its origin in these quantum mechanical fluctuations?

    I hadn’t thought about this for a while (I more work closer to #10 these days), so I’ve looked in Kolb and Turner
    to see what they think. Basically they seem to say that as a wavenumber k
    crosses the horizon, the quantum field mode associated with momentum k
    “freezes in” as a classical perturbation. It seems the process of this
    classical freezing is irreversible, or is that not right?

  • Sid

    Would love to know if the talks of this conference will be posted online? Also, the other conference attendees might have posted blogs of their own about their take-away from the conference? If you know of any such blogs, it’d be amazing if you could post their links here. Thanks!

  • Fred

    Sean, in your view, does the recent paper 1108.3080 solve the entropy problem in 7, as the paper claims?

  • Chris

    Humans must not fit into that 1.5 billion heartbeats. Our lifespans have going from 30 to 80 years so unless our hearts were beating a lot faster back then (maybe when we were outrunning tigers) it clearly isn’t as simple as you made it seem.

  • http://calamitiesofnature.com Tony

    Chris – That’s just a factor of two difference. These are just rough figures.

  • http://www.bboyneko.com bboyneko


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  • Ruda

    Maybe time doesn’t exist, and only the far future at the end of time is real. The timeless eternal reality of eternal memories by one consciousness remembering. The future is far more real than the past. And yes, that one consciousness has a fallible confabulating memory.

  • http://www.naturalism.org Tom Clark

    “The past and future are equally real. This isn’t completely accepted, but it should be. Intuitively we think that the “now” is real, while the past is fixed and in the books, and the future hasn’t yet occurred. But physics teaches us something remarkable: every event in the past and future is implicit in the current moment. ”

    So you’re saying the future too is fixed and in the books, and that this should be completely accepted. Given the implications for commonsense notions of human freedom and dignity, it’s unlikely this will ever come to pass, but I appreciate your advocacy.

  • http://Timelessness.co.uk Matt Welcome

    Ok =)

    how do i put this ?

    Einstein suggested – ‘For we convinced physicists, the distinction between the past,present, and future is just an illusion, no matter, how persistent’.

    I’ve looked at the notion of time in great detail. I seem to have a rather analytical mind. And, it seems to me that what we are trying to work out essentially is ‘how does the world work?’

    If we ask this question, we may find some meaningful answers. But if we ask loaded questions, such as “does ‘TIME’ exist”, or “What IS TIME”, then perhaps these are biased and misleading questions that may send us down a very long, and very confusing, wrong path (if it transpires ‘our ‘assumption’ that Time’ exists is actually unfounded, and false).

    Perhaps instead, we can ask the unloaded question, ‘what do we actually, directly,observe?’

    To which we might answer, at the most basic level, ‘I directly observe matter existing, moving, changing, and interacting’.

    Then we could ask “Is matter, existing, moving, changing and interacting, enough to explain all we observe and attribute to the existence of (mysterious, and intangible) ‘Time’ ?”

    To which, I would, after very careful consideration say,

    “Yes, the suggestion that perhaps in the universe, matter just exists, moves, changes and interacts ‘now’ (to use a redundant word), can explain, without exception, all, of the observations that lead us to the (incorrect) idea that, extra to what we directly observe, a thing called ‘TIME’ also exists”.

    In other words, it can be logically deduced that there is no ‘extra’ thing called Time.

    Things may ‘just’ exist, move, change, and interact. And this alone can lead us to wrongly assume that a ‘past’, and a ‘future’, and a flow of a thing called ‘time’ between them, exist.

    ‘TIMELESSNESS.CO.UK’ links to more info on this, my book draft ‘A BRIEF HISTORY OF TIMELESSNESS’, and some videos of a couple of talks I have given on the book.

    Matt Welcome – London.

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  • Shane


  • http://jbg.f2s.com/quantum2.txt James Gallagher

    If Time is fundamental and Space is emergent then Einstein will, like Newton, be a creator of a brilliant but only partially (more) accurate theory of Nature.

    ~200 years from Newton to Einstein, ~100 years from Einstein to the new paradigm, so maybe ~50 years for the next one.

  • Rob R.

    We used to think that “temperature” was a basic category of nature, but now we know it emerges from the motion of atoms.

    Same for time, no? You said as much in your #3:

    Einstein came along and explained that how much time elapses for a person depends on how they travel through space (especially near the speed of light) as well as the gravitational field (especially if its near a black hole).

    Or, as a layman, am I missing some nuance or other (i.e., “we’ll need to understand quantum gravity much better before we can say for sure.”)

  • Tbird49er

    Regarding an earlier comment (#5. Steffan), I’m not sure “evolution” invented death, but it is a fact of life, as we know it (do we perceive it like we individually perceive time?? lol). Interestingly, even if we lived very much longer, humans have a fairly unique adaptation ability (certainly not exclusive, since we’ve seen other animal species pick up “tricks”/skills and pass them on to their groups). We may not evolve as quickly genetically if we’re living a thousand years (via DNA), but our “intelligence” allows us to develop our own adaptations at pretty phenominal rates. Maybe, as with the most complex modeling/problem solving accomplished with thousands of inter-connected processors (computers), we humans might be able to adapt and solve our most pressing problems when united together for a survival purpose. We undoubtedly will get such a chance in our grandkids lifetimes, if not during ours (whether from dramatic climate change, asteroid impact, cosmic bombardment, etc.). We do live in exciting times…as we individually experience it.

  • http://digitalcuttlefish.blospot.com Cuttlefish

    One thing everyone should know about time.

  • Pierre Stjepanovic

    «every event in the past and future is implicit in the current moment» doesn’t mean that the current moment determines what the future will be, merely that it implies it. It’s alright Free Will, you can stay…

  • paul kramarchyk

    Imagine a one point particle universe. Just one stable particle. If true, then:
    — motion and location are meaningless
    — no time because no change
    In other words, time is born from change. No change. No time.

    My thought experiment is far out, I know. But does it say something about whether “time” is more a consequence of other things than it is a fundamental thing itself?

  • Lazy B Astard

    1.5 billion heartbeats?

    So exercising to get the heart rate up just uses up your life faster then?

  • David O.

    How to square increasing entropy – which says there is an arrow to time, pointing only one way, with all the physics/cosmological equations which say that time does not have an arrow? Have I fundamentally misunderstood something – or do we have a paradox?

  • Nate Whilk

    #18 Chris wrote, “Humans must not fit into that 1.5 billion heartbeats.”

    #19 Tony wrote, “Chris – That’s just a factor of two difference. These are just rough figures.”

    Actually, the linked NPR essay says this: “Human beings used to fit into this pattern, but now that we have learned to drink safe water, wash and bathe and create medicines, we last longer than our size would predict.”

  • Ronald Stepp

    I don’t need to live forever. I just need to live long enough that I can live long enough to live forever.

    Each time they figure out how to expand our lifespans I’ll be around to get in on it, heh.

  • Kaleberg

    Apparently there are time neurons for recording time, even if nothing happens. They work a lot like place neurons, except they build a framework for sequencing and measuring the duration of things rather than tracking their physical (or metaphorical) layout.

    There’s an article in Science about it at:


    It involves, rats, time, flower pots, sand, cubes of cinnamon and balls of oregano. That’s not as interesting as the stuff Sean works on, but now you have to read it.

  • Mandeep

    I gotta say — what esp. struck me here is that time is THE most used noun in English??! Whoa! Interesting, and a quick check reveals you’re essentially right , as long as pronouns etc. are discounted:


    But isn’t that fascinating also — it’s only the 55th most common word at all! Apparently, we use verbs, pronouns, adjectives, adverbs, prepositions and whatever else a heckuva lot more than nouns.. hmmm..

    In fact, you may like this too — there are very few nouns at all in the top 100, and 2 of the others are time-related as well: “year” and “day”..!

    Thx, otherwise also interesting post!

  • Joffaboy

    “Time flies like an arrow. Fruit flies like a banana” — Groucho Marx

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  • bratty


  • Jordan

    “Wibbly Wobbly, timey wimey, spacey wacey.”

    The Doctor

  • http://futureofutc.org Rob Seaman

    #11) Timekeeping, not time per se: Time-of-day has always been synchronized to the natural rhythms of Earth rotation. The Radiocommunication Assembly of the International Telecommunication Union will vote in Geneva in January 2012 whether to permanently disconnect all clocks on the planet from the rotation of the Earth. (http://futureofutc.org/)

  • Tbird49er

    The clockworkers have a union? International Brotherhood of Cuckoos?!! lol

  • joejta

    I happen to know the Guy who created Time. Invented it you might say. To Him, the beginning is as fresh as this moment right now. Even from this point in time, He can see our distant future. We can learn much from Him, if we will only pay attention. Not a technical discussion, but an interesting and beneficial one for us.

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  • Sanjay Singh

    Shouldn’t para 8 read “part of the job of complex systems is to decrease entropy”?

  • KanzasTabasco

    @Lazy B
    Getting the heart rate up during aerobic exercise serves to strengthen the heart so that it beats SLOWER while not exercising (which is most of the time). The net effect is fewer heartbeats per day.

  • keith

    4 is interesting! I touch my toe and nose simultaneously and feel the toe slightly later. I’m autistic. This corroborates a lot of recent results.

  • opterios

    Excellent article!

    On the biological/sociological aspect, you might find this interesting (though not physics related at all): http://bit.ly/olEXeT [youTube]

  • Fayanora

    Number 9 is not entirely accurate. All animals live to 1 billion heartbeats, with the exceptions of humans and some domestic animals. Humans live more than twice that long; if humans only lived for 1 billion heartbeats, we would all be dead by age 30.

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  • http://nosingularity.blogspot.com/2011/09/mental-calculus.html derivative

    I would add that we build our image of reality based on a finite number of events.

  • http://lablemming.blogspot.com/ Lab Lemming

    Isn’t #2 fatuous, given that we cannot ever possibly know things like when radionuclides will decay?

  • steven johnson

    The last I recall, there was an effort to reconcile quantum indeterminism with the appearance of reality we see everyday by a method called “sum over histories.” They wanted to use the concept of decoherence I think. Reading as carefully as I could, I believe they discovered that the past was just as indeterminate as the future. Which if you think about it, seems a perfectly natural consequence of the past and future being indistinguishable on a quantum level. If both past and future are indeterminate, in what sense are they real?

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  • http://s33light.org Craig

    I take a different approach to understanding time but it involves a radical departure from conventional physical cosmology. (I know that makes me sound like a crank, but I haven’t found any counter arguments very convincing so far, so I do think there is a possibility that this hypothesis has real explanatory power).

    Time is subjective because energy is subjective and energy is the container of time (as space is the container of matter). Energy subjective??? Yes. Energy can only be experienced. It’s not a glowing cloud that gets coiled up inside of springs and released through action, it’s just the experience of a spring or a nerve or a human being experiencing a change from tension to release or vice versa. Of course I’m simplifying here, but stay with me.

    Our experiences of the energy of something else – seeing a spring pop, feeling a log burn, reading a person’s emotional shifts on their face (yes, that’s energy too), is a second hand experience. The first hand experience is our nervous system imitating those changes as the content of our awareness.

    That is what we sense, feel, see, etc is the ‘interior’ of our own nervous system recapitulating the changes it is detecting through the body cells, tissues, and organs, of the changes in the environment. Experience = change = energy. No subjectivity, no change, no energy (not talking about any one organism’s subjectivity, I’m talking about the ontological necessity of perception or detection in the cosmos to define energy).

    If you can get the gist of that, then maybe it will make sense that time is the container of energy. It doesn’t ex-ist, it in-sists. Since energy is change, and change requires some sort of fundamental capacity to sense that there was an original state to begin with and an extension of that sense into memory to sense that the now state is different in some way from the original state, time can be understood as energy which is not occurring ‘now’.

    The sequential nature of time is important, but it is not primitive. On this list, the #3 trumps the #1. In the vernacular sense of ‘time’, I think that it is just an aggregate measure of physical change modeled in a linear fashion. It has no existence of it’s own beyond our sense of sequential causality (which evaporates predictably under altered states of consciousness – dreams, drugs, trance, etc). We are the ones who interpret the digits on the clocks and the calender squares as a shared temporal text. In reality, there are no days, just astrophysical orientations woven together by our memories and monitoring of regular oscillating patterns.

    As far as aging and entropy goes, those are existential functions (so having to do with the reflected secondhand side of our experience…matter). If my hypothesis is correct, entropy is actually a function of space more than time. If you think about two sandcastles, one of which is confined within a glass, castle shaped jar, and the other naked, entropy is going to be staved off for much longer under glass.

    Space is to matter what time is to ‘energy’ (experience of change). If you think about a universe with nothing at all in it except a single proton (or a ping pong ball, whatever, some kind of ideal sphere of matter) and no exterior phenomena as a frame of reference, there can be no space. There’s no position or speed or spin. For those things you need some other object to relate to to be able to generate the relation of space – so space would not be a rich hyperdimensional topology of superstrings and intangible vacuum energy, it would in fact be a true void. A void created not by a Big Bang, but by a Big Shatter of the singularity (which exists still across the gaps of spaces and insists still through the stories of times).

    I know, it sounds completely nutty, but I’ve spent a lot of time debating with people about it and have not heard any new convincing objections. I think all of the irreconcilable strangeness of entanglement and uncertainty, gravity and electromagnetism, mind and brain, perception and relativity, entropy and cosmology, QM and GR can all be tied up neatly by using a sense-based model of the cosmos.

    Sorry if I’m hijacking the thread here, it’s hard to comment on time in this model without commenting on everything else.

  • Edwin Sosa

    I am not a physicist, but physics questions and “theories” are all over my mind, mostly from a philosophical perspective. Lately I have this persistent idea that time is “merely” an illusion, just another part of this whole illusion that we call “reality” as Einstein points out. Therefore I am believing that all of the time pieces are actually happening at the same “time” which complies with #2 (The past and future are equally real), it is just our “consciousness” and the illusion it is being effected by that make us believe that past is gone and future is yet to come, but actually everything is just there happening all at once.

  • Skybro

    I have always held to the idea that time is just man’s feeble attempt at measuring that which is immeasurable. We just chop it into chunks (days, weeks, months, years, etc…) in order to more easily process something we are unable to fully grasp.

  • Tony Serio

    How does every living thing only get 1.5 billion heartbeats? Doesn’t our heart beat faster than once per second? If resting heartrate is around 70 beats a minute, the answer is yes. When we’re babies/children out hearts beat even faster. Well 1.5 billion seconds is equal to roughly 48 years. The math doesn’t add up for humans.

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  • Alex

    “You and I won’t live forever. But as for our grandkids, I’m not placing any bets.”

    Yeah, well: http://youtu.be/JOxlpVm96QQ?t=1m43s

  • http://thefloatinglantern.wordpress.com Tim Martin

    Is it not an oft-used lie that entropy and disorder are the same thing? Entropy is about energy distribution, not what looks neat to human brains. A ‘disordered’ (messy) room with clothes strewn about does not have access to any more or less energy states than an ordered room. Or if you have some ice cubes floating in a bowl of water, ‘order’ increases as the entire system becomes liquid water, but entropy increases as well.

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  • TM may

    Stephen said: “Imagine a society where the industry tycoons of the 19th century still own the majority of money and influence….”

    Umm, is that NOT the present reality??

  • jery

    Time (na na, nana na)
    Time is time (na na, nana na)
    Labadab dab dab time (na na, nana na)
    Tiiiiiiiime! (na na, nana na)

  • Vapor Eyes

    “Time is an illusion. Lunchtime, doubly so.” -Ford Prefect

  • http://magicdragon.com Jonathan Vos Post

    “if reality were completeLY different from moment to moment. ”

    I’m quoting, with attribution to you, these points in a science fiction short story, “Time Is Out of Joint.” I try to tie in the recent arXiv paper Joel Hamkins’ The set-theoretic multiverse. I posted a lovely quote from that paper on your Facebook wall.

    I’ve taught half a dozen times a 1-week college level adult education course on Time Travel that uses Time Machines: Time Travel in Physics, Metaphysics, and Science Fiction (ISBN 9780387985718) by Paul J. Nahin as de facto textbook.

    Of course, my understanding of Time is influenced by our mutual friend Kip Thorne, and my co-authors Isaac Asimov, Ray Bradbury, and Robert Heinlein. Ideas that fall short of working, equationally, and would likely not get past a referee, are still grist for the fiction mill. I’ve been paid a number of times for rather goofy Time Travel stories.

    I can email you the complete draft of the story when done, to ensure that I have your permission.

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  • Rob

    “The past and future are equally real.” @ STan and others – maybe all slices of time (past, present, future) do happen simultaneously. Considering #2 above, maybe we are not traveling up or down a time stream but rather along an axis that crosses all possible variations of past, present, future. What a mess.

    Perhaps ‘life’ could be defined as forces that defy entropy. During the course of ‘life’ our existence is in contradiction to the laws of entropy. When we understand those forces, we will be able to better define this concept of ‘life’. The state of ‘life’ is more ordered than the work of attracting forces like magnetism or gravity. And our point of observation of ‘time’ is from the seat of life. Rocks don’t perceive of, or witness, time.

    And as for the refrigerator, it doesn’t design and assemble itself, it requires us to do that. Again, it retains its form and function only breifly.

  • Rob

    @Stefen re: #9 – I won’t go willingly, there is more than enough space for us and every future human generation in this universe. In fact, we better keep and create every human we can. The problem is that we as humans are too focused on staying at home. We spend our money and energy on competing for resources and tribal domination, when the human race should be trying to expand beyond this planet. Take life with us and continue to fill the universe, there is no room for decay and death, what a waste.

  • Rob

    @Tim, but is did take energy to change the state of those messy cubes of water to ice…

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  • John Merryman

    I think the problem with time is that we think in terms of the present as moving from one event to the next, but the only reality we perceive is the present and it’s the changing configuration of this present that turns future potential into past circumstance. . So it isn’t the present which moves from past to future, but the events which go from future to past. The earth doesn’t travel the fourth dimension from yesterday to tomorrow. tomorrow becomes yesterday because the earth rotates. Reality doesn’t break into different worldlines with every quantum indetermination. It’s the collapse of future possibilities which creates past events. Time isn’t a vector, it’s a process.

  • Tomas

    Time does change as one ages. Think of time in terms of an individual’s lifetime. To go from age 1 year to age 2 years, an individual has to live another lifetime. However to go age 20 years to age 21 years, an individual only lives an additional 1/20 of a lifetime. Thus the older an individual gets, the faster time, in terms of lifetime, progresses. Of course, Chicago Transit Authority (later to be known as Chicago) had it right in one of their early songs which asked “Does anybody really know what time it is? Does anybody really care?”

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  • Rob

    As described by Sean Carroll in “From Eternity To Here”, time IS a coordinate in space-time. The snapshot of the Universe at 6pm today is different than the snap shot of the Universe at 9pm tonight. Your GPS may say you are in the same spot at both of those times, but the Universe would have changed around you, and that new TimeSegment you are in has a different coordinate in the SpaceTime Universe. As I understand…. So, disappointing, time may not be anything other than the observation of change, including entropy. Nothing magical about that. Shucks. I wonder if we could hold an absolute position relative to an unknown point of reference, would time stop (for us). I guess to do that we would have to stop time. It becomes circular.

  • http://www.groupsrv.com/science/about193612,html Anthony A. Aiya-Oba

    Time is changeless Space. -Aiya-Oba (Philosopher)

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  • Buster

    After reading all the posts I have concluded that time ends when I die.

  • http://s33light.org Craig

    @Anthony …and (or?) spaceless Change.

  • http://www.focusfinearts.com David L. Nelson

    Instant Inspiration Translation

    When the benefit of goodness translates to the over-bounding plusness of allgetting for the many we are all applause for the cause of clapping as gazing around to find cheek lifting smile style for long while when electronic audio party favors arrive in many flavors so joy juice flows throng grows in expansive trance dance eye glance round n round as bones jump to sonic shoe shuffle song mix tricks transfix clusters of crazy cats toast the most vibe ripe trip hop candy shop score store street smart instant art at the start beyond description sans prescription where sparks sizzle between synaptic snaps as the whole house hangs high above the sky born to fly from here to beyond the margins of any man made map fades into the ether place is then revealed upon your face we let loose the sticky strings which tie us to many things and drift away from gravity and it’s a gas as we become unglued from the get more moods heavy condition we evoke our own rendition via the collective minds ignition of sweet cognition so it’s there we all begin to share the aspect of our eternal travels and the thin mystery of moment unravels to reveal what’s really real as mystic events peal away the layers of paper lies from our naked eyes where time terminates ticks n tocks we step across the invisible line as easy as slipping into the soft abyss of bliss where that, becomes… this!

    © 2010 • D.L. Nelson Ironworks Publishing & Focus Fine Arts®

  • scribbler

    Quote: Maybe, as with the most complex modeling/problem solving accomplished with thousands of inter-connected processors (computers), we humans might be able to adapt and solve our most pressing problems when united together for a survival purpose.

    Unquote: Time will tell… 😉

    They should put “like” buttons on these comments. Seen some GOOD ones here…


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  • mikmik

    First, every event in the past and future is implicit in the current moment therefore they are equally real? That is no physics I have ever heard of. What is implicit in the current moment is that there is a direction of time; the arrow of time. It says that because the current moment is the result of the past changes, so will some future specific moment be the culmination of its past events.
    The only way that the future is implicit now is that there is no now without a future. In no way at all do future events specifically affect the present moment!! It only means that time hasn’t stopped now, FFS. Three days from now, or three billion years, our universe might cease to exist in the way it does now, perhaps a collision with some other part of the multiverse, or the sudden, spontaneous decay of gravitons into zigzag and corkscrew (flavors, like gluons’) anti-boson pairs, or whatever, we have no idea of how reality crumbles, yet it might or might not. This changes nothing about our present characteristics of reality, we only know that right now, we are in the future of the past and the past of the future, LOL. Having a future allows our present existence, nothing more, nothing less. Don’t give me specific future events crap. There is no physical theory that predicts, let alone concludes, a determinate future, let alone a future that determines or influences its past. The future is indeterminate, as any wave functin wil show you.
    Finally, time can exist without matter or energy(they’re the same, Craig), but matter cannot exist without time, for matter is only defined by interaction which is exchange of energy ie change.

    @craig#58: Time, energy, physical existence, is not subjective, okay? Energy and matter are equivalent, not two different and separate states that have different physical laws. Matter is ‘experienced’ so is also subjective by your reasoning. Kinetic energy can be ‘released’, from potential energy, and a coiled spring can uncoil, or an atom can fission, without anyone experiencing it, even without anything experiencing it.
    Saying that energy is the container of time is a non sequitor. Arbitrarily assigning a perception as subjective is meaningless, because what you mean, I think, is not ‘subjective’ but ‘experiential.’ We experience time(change), matter(inertia), and energy(work), but so does everything – albeit not consciously. All you have done is say that a tree doesn’t make any noise when it falls if no one hears it.
    You also said, “and no exterior phenomena as a frame of reference, there can be no space.” How do you know? A sphere has volume, doesn’t it? That is space. If the universe has so decayed(entropy) and expansion has accelerated past the speed of light, then fundamental particles will have no way of interacting and therefore determining spin or anything else, does this mean that time and space have ceased to exist? That the particle suddenly ceases to exist? That expansion ceases to happen/exist? That zero point energy ceases to exist, suddenly?
    No. Space cannot exist without time, nor time without space, for without space, there is nothing to change, move, decay, whatever, and without time, space does not have duration, a period in which to exist.

    As far as I can tell, this is unresolvable using pure reason without making assumptions(which is my assumption!). Space and time are co-fundamental(lol wut?), or fundamental properties of each other. Obviously, I am just inelegantly restating that we exist in a four dimensional time-space continuum.

    I just hope we don’t spontaneously cease to exist before I hit the submit button so someone can set me straight =]

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  • Charon


    Disorder increases as time passes. At the heart of every difference between the past and future — memory, aging, causality, free will — is the fact that the universe is evolving from order to disorder.

    Clearly that’s not true, about aging. You point this out yourself in #9. That’s because of biology, not physics.

  • http://www.santafelead.org Gary

    I have often thought of time as an invention for our convenience, a construct used to mark units in terms of years, months, days, hours, minutes and seconds (nano included). We even mark the passing of time with birthdays, anniversaries, celebrations, and history. In the natural world, we are governed by seasons, the movements of the earth and the planets, the sun and the moon, and the indigenous peoples were much more in sync without watches and clocks and calendars. That said, I like these ten descriptions and movements and being part of them, and whenever possible, merging past, present and future into one great experience.

  • BigBangBoom

    Time seems to be a side effect of having a limited speed of communication. If the speed of light or the speed of communication was infinite we could be anywhere in “no time” and there would literally be no time.
    I think this may also explain how time started at the Big Bang. Einstein’s famous equation E=mc2 is not currently “flipped” into c2=E/m. If E is in fact quantum energy E(q), vacuum energy, cosmological constant energy or whatever name we give to the expansionary energy that fits into Relativity’s equations this flip may be valid. If so prior to the formation of mass from E(q) (mass = energy) c would have been infinite (since m=0) and there would have been no time.
    Put another way then mass creates time by limiting the speed of light.

  • Kari

    somewhere between too little and too much is something worth pursuing, somewhere we are going….never to arrive

  • Shantanu

    Sean, everyone is waiting for your comments on Tegmark’s paper.

  • Bob

    Check out “Nothing is Random” by Mark Helprin, an excerpt from his book the Winter’s Tale. It may not be true about time, but it’s stuck in my mind for many years…

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  • Mut

    The title sounded intriguing, but then in the first item:

    “Time organizes the universe into an ordered series of moments”

    Er, no. If two points in spacetime are not in each other’s lightcones, you can’t define an ordering. C’mon, special relativity is more than a century old now…

  • http://metamodern.com Eric D

    Re. “…why was entropy low near the Big Bang…?”

    I am puzzled by the idea that there is a problem here, because in a strong sense, entropy was also nearly maximal.

    As I understand it, most of the important physical degrees of freedom were near equilibrium at an early, pre-nucleosynthesis stage of the Big Bang expansion (disequilibrium was largely confined to weakly coupled degrees of freedom). Thus, the early universe was — given its volume — near its maximal entropy with respect to the physical interactions of interest to biologists and astrophysicists.

    Expansion of the universe, by expanding the available configuration space for matter, increases the potential maximal entropy of its contents. Thus, expansion allows entropy to increase relative to what had been a state of lower, and yet maximal, entropy.

    Viewing this from a thermodynamic perspective, the expansion provides us an ever-increasing volume of ever-cooler vacuum to use as a heat sink.

    So, given the expansion of space, I don’t see how the increasing entropy of the universe per se poses an additional problem. The problem of the homogeneity of the early universe is a puzzle involving a surprisingly degree of equilibrium, that is to say, a problem of surprisingly high, not low, entropy.

    Am I missing something here?

  • CuriousTech

    Quite a lot of interesting subjects in this article, and the comments as well! Great work. Deja Vu may explain para 5 somewhat. The scenario process (normally only remembered as dreams when waking) is accessed by the conscious and is indistinguishable from memory. This gives merit to the idea that reality is delayed between sensing and consciousness awareness to give time to process and prepare for “current” thoughts and actions.

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  • red

    Time is a human construct and nothing more. It’s real in the way we use it, to measure events, to order our lives, etc… but other than that time doesn’t exist in nature, in the universe, and even at the quantum level. We perceive the idea of time as the progression of natural phenomenon, but at the fundamental level there is no time. There is nothing in nature that says after so many pulses of a cesium atom (a crude definition how we define a second) that a cell should split or an atom should decay or even that a light wave should travel (x) amount of distance. Everything in nature, even down at the quantum level works in either cycles or happens because of interaction with something else. Because of this and because of how we have defined time in our human lives it appears as if nature does work by a clock, but once you really understand time as we define it, then you can see that time is truly relative and because of that, fundamental time does not exist.

    Think of it like this. The speed of light is considered fundamental and unbreakable but as we define it, the speed of light is 299 792 458 m / s. What if we chose to define the length of a second differently? Then the second would either be longer or shorter and thus the speed of light would be different. You see time is completely relative and has no real fundamental connection.

    Time is merely what we use to create order out of our lives and/or chaotic systems we don’t fully understand.

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  • Lee

    Space/Time are properties of Dark energy/matter like sweetness is to sugar.

  • David Ferrell

    Just heard Sean on the TV program “Through the Wormhole” asserting that the direction of time is related to the ongoing increase in entropy since the beginnings of the universe. I’m a layman, not a physicist, but I challenge the notion that entropy (as it was defined, meaning more and more disorganization) has increased since the beginning. What greater chaos could there be than the soup of particles immediately after the Big Bang. Over the eons, these primary particles have organized themselves into galaxies and stars, complex atoms and molecules, and planets like ours (I presume we’re not unique) rich with weather patterns, geologic structures and even, in our case, life. Humans continue to create increasingly organized societies and ever more sophisticated buildings, cars and electronic devices, among many other things. This is increasing entropy??? Yes, the energy driving all this may eventually dissipate, but I would guess that the chart of the universe’s overall entropy is still trending down and has not yet hit its trough. And, again as a layman, I suspect that this energy may ultimately be conserved, with “spent” matter coalescing into massive forms that re-explode or re-convert matter back into new cycles of energy, leading to new types of physical order. Let’s speculate about time in some way other than linking it to this alleged entropy increase.

  • Peteris

    The ’80 milliseconds in the past’ doesn’t really work well with known, researched facts about human experience in audio processing. For example, when playing music, a 20 ms increase in latency (time between your hands causing the sound and hearing it) is easily felt and noticed by the musician. 80 millisecond difference is clearly noticed as not simultaneous – 8 milliseconds might be a limit, but not 80.

  • Richard Davis

    Mikmik #86 seems in my view to have it about correct. Absolutists will continue to adhere to a linear description of their universal precepts. I am late to this discussion, but believe anyone interested in this topic might be rewarded by a look at fractals and chaos theory.
    We may like the concept of past and future, but Augustine of Hippo stated over 1600 years ago that neither exist. The past once was present, but is gone now and cannot be retrieved (only partically and poorly recreated by memory) and the future is not here yet and cannot be known. That leaves the present, which in quantum theory, is a duration of 10^-43rd seconds (for those who like the exactness of counting). Quantification of the successive “nows” by clocks of various types does nothing to answer the more fundamental metaphysical question: What is Time?
    I suspect that thinking of Time as a fourth dimension only muddles the consideration. Ditto the stuff about psychological experience of time (age of perciever; pain vs. pleasure, et. al.).
    Physics is not sufficiently philosophically inclined to help my understanding of this Meta-concept.

  • RaulJones

    “Of course time exists — otherwise how would we set our alarm clocks?”

    Proof that “time” is a man-made institution.

  • steven johnson

    Brain fart in post #55: It’s consistent histories approach, not sum over histories approach. Consistent histories cannot find a determinate past any more than it can find a determinate future. Again, this is to be expected as it seems to be consistent with the reversibility of the equations of fundamental interactions. This also seems to be inconsistent with the block theory of spacetime Prof. Carroll seems to telling us is the prevailing opinion of the conference members. But this too is to be expected since no one, so far as I know, has explained how mundane reality is to be reconciled with universal quantum entanglement originating in the Big Bang.

    It seems a little odd that a cosmologist would opt for entropy as cause for emergence of time. I would have thought that expansion of the universe would be their first thought.

    Total chaos is low entropy. I think a simple explanation could go like this: Since every part of chaos is indistinguishable from another, there are no parts to arrange in different patterns. Essentially, there is one universal hodgepodge. Entropy is the tendency to increase the number of ways the parts of a system can be arranged. (This approach tries to relate entropy to Kolmogorov complexity. Which may be a gross amateur error, but I think is the standard view.)

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  • http://www.slowpost.tumblr.com James Reeder

    Anyone interested in nostalgia and anticipation should take special note of the fifth thing in the list. The points about memory and imagination only reinforce de Selby’s theory of time and travel included in the Flann O’Brien novel “The Third Policeman”: “Instead of going to the railway station and inquiring about trains, he shut himself up in a room in his lodgings with a supply of picture postcards of the areas which would be traversed on such a journey, together with an elaborate arrangement of clocks and barometric instruments and a device for regulating the gaslight in conformity with the changing light of the outside day. … Like most of de Selby’s theories, the ultimate outcome is inconclusive.” But I feel now it is less so.

  • minda

    i think time is related to our weird ability to have memory. imagine if you have no memory, then there would be no way to say if things move or not, i.e. we could not compare. world would seem totally different then

  • http://engage.is John Corn

    McTaggart is turning in his grave with affirmation 1.

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  • Jon H


    Can you express these ideas in terms of cubes?


  • Roger Walker

    Reading #2 (past & future) I immediately thought of the 2-slot experiment, which indicates that every quantum particle (past, present and future) “knows” each and every other quantum particle.

    Is this relevant?

  • http://www.thestillnessbeforetime.com/ Michael Holshouser

    The Stillness Before Time

    There is really only one Way.
    It is without division or boundary.
    It is without name or theology.
    Awareness is its scripture,
    Here now its venue,
    You its witness,
    Your life the journey.

    * * * *
    There has ever been now,
    Will ever be now,
    Is ever now.
    Never has there been any time
    Other than now.

    * * * *
    The manifest dance is timeless, momentary, eternal.
    A reverie without beginning, without end,
    Without cause, purpose or meaning,
    Neither definable or explicable,
    For it is beyond all rational appearances.
    It can never be known, comprehended or understood
    Except in the most roundabout, circumspect, fluid, abstract ways.
    And in that which is intuited there is no gain or reward,
    One simply wanders spontaneously free,
    Whatever the course.

    * * * *
    All mythos, all sense of time and history,
    Is the make-believe of adults.

  • beagle197

    These are random “points”, and I am not convinced they are all true. “1. Time exists” (?) S. Hawking said it better that at a very low level, e.g. quantum scale, time is a foam, with particles appearing and disappearing. If “7. Disorder increases as time passes” were true, why are humans so advanced in comparison to our local universe?

  • Yeshe

    Some of the statements which people have made appear wrong or unwise to me. Time is a product–or more accurately perception–of mind. Time does not “exist” independent of mind. Unless there is mind to perceive time, there is no time.

  • http://None Robert

    What is relevant? I don’t believe time is one of those relevant discussions.

  • abby

    Does anyone remember that line from the song — “time keeps on slippin’. slippin’, slippin’ into the future.” that’s what came to my mind…. maybe not relevant but funny what you think of when you read an article like this….

  • Ricardo

    Time doesn’t exist! Time is space in movement. Think about this.

  • oceanbear

    Before you buy into the “time” story try reading Julian Barbour’s “The End of Time”. You can also go on his website http://www.platonia.com/ideas.html.

    The book really puts a twist in the conventional understanding of reality and time.

  • Charlious

    Time is Magnificent. It’s there to tell us we’re late for work, a party, the first race of the day. ETC. Time is running down slowly till when it stops the universe will die. “Can Entropy be reversed.” that question is “The Last Question.: it’s my most favorite story by Dr. Issac Asimov. if you can find it read it. The last page will blow your feeble minds away.

  • Not Sean

    I love how people keep asking the author, Sean, questions, yet he dasn’t deign to reply. Maybe, in time, he will reply. Pun most thoroughly intended.

  • http://subgenius.com Joe Cosby

    “The past and future are equally real”

    There are a lot of real problems with what you’re saying here.

    First you’re saying that the future and past are implicit in the present. True, but that’s a lot weaker than the Einstein quote later that time is a fourth dimension. The past and future are IMPLICIT in the present, but do they actually exist, the way the room down the hall exists? Einstein is saying yes, you’re not quite.

    But Einstein also said that “time is what we measure with a clock”, and I think that’s all we can say about time.

    And personally I disagree with Einstein that time is like space. The Grandfather paradox is unsolveable if they are, but if they aren’t it isn’t a paradox at all, just a sign that we were looking at things wrong.

  • Uther Pendragon

    Wind is not moving. Flag is not moving. Mind is moving.

    If the future is as real as the past, then free will must be an illusion. Cool. I can stop trying so hard now.

  • bo

    10 Things Everyone Should Believe About Time, Because Sean Believes Them. Everybody should have a position regarding metaphysics; thanks for sharing yours.

  • Leonard

    Time is the human attempt to measure the rate of decay of the universe; or measure the rate of evolution of the universe, to put it nicely.

  • robert wright

    Ya, everyone gets the same number of heartbeats, except for the exceptions. Birds squeeze off as many as 10 billion beats, and a human will knock off 4 billion without being all that amazing. Heartbeat makes a useful estimator of metabolic rate, which roughly equates to oxidative stress, but not all organisms handle that in quite the same way. The only real hard and fast rule in biology is that life will do pretty much whatever it pleases.

  • George

    > So you’re saying the future too is fixed and in the books, and that this should be completely accepted. Given the implications for commonsense notions of human freedom and dignity, it’s unlikely this will ever come to pass, but I appreciate your advocacy.

    In a sense, the future is fixed; it just has not happened yet. We might not like that idea, but that does not make it false. Everything up until now has happened in exactly one way, and that is how time will continue to pass. It does not make our decisions any less valid. Just that things were bound to happen this way.

    People like to think they are more important than they really are, and that we are in charge. They do not like to feel helpless or worthless. But this concept is not rooted in objective reality. If you think about all the complex processes that had to occur for millions of years for us to end up in this precise moment, well, to think “I control my own destiny!” is a comforting thought, but patently false.

  • R. Wright

    “The equations don’t lie”? I hope I don’t have to point this out to a physicist, but equations are models, not omniscient oracles.

  • Dave Meriwether

    I think you’re right,…. no, I’ve changed my mind. Time has passed between the two decisions without motion.

  • sayhi2yourmom4me

    I have done a lot of science reading. If I had to describe spacetime in one sentence I would describe it as “a medium for energy to express itself”. Energy can exist in space as masss, it can exist as movement through space, over time, both space and time are nessesary for the objects in the universe to exist, and the energy of motion is the same ultimately “stuff” as energy that makes up the mass of the object that is moving. Space and time are also correlated and blah blah blah but I would definately regard time as a real “thing” just like I regard distance or area or volume as real “things”. To those who say that time doesn’t exist, and offer up a simple one or two sentence explination, or that the “future” isn’t “real” yet, probabily have not been shown how deep the relationship between space, time and energy goes.

  • Richard Alexander

    “Eyewitness testimony, it turns out, is one of the least reliable forms of evidence allowed into courtrooms.” – That’s an old chestnut that I’ve seen used only by those who are defending evolution in an evolutionist-creationist debate, specifically to justify calling a study a science when no one was present to record the events the study pretends to study. As it happens, the statement is, if not untrue, at least misleading. Direct evidence–including some forms of witness testimony–is more reliable than circumstantial evidence. The fact that one can monkey with witness memory does not discredit all eyewitness testimony. As usual, evolutionists are liars.

    “Other than creationists, most people have no trouble appreciating the difference between ‘orderly’ (low entropy) and ‘complex.'” If that were true, there would not be much point in talking about it at a physics conference. But, as usual, evolutionists are liars. Speaking of which, what is with this fascination for bringing up evolutionist’s arguments at a conference on time?

    You must have a lot of frauds going to Norway.

  • CuriousTech

    106. Peteris Re: 80ms is too long. It could be that reacting to sound takes a higher priority over sight, so it could possibly take different times for different senses IMO. Touch may be even less complex to the point of taking even less time. Studies like that always seem to leave out common questions and generalize way too much. If only they would ask normal people BEFORE performing the study. :)

  • js290
  • Ken

    There is no present, only past and future.

  • Richard Alexander

    @CuriousTech – Not sight; touch. 80 ms is too long to react to either sound or sight. In 80 ms, a car traveling 30 mph travels about 40 inches (0.528 inches/ms). We might not be able to react that fast, but we might notice if something appears just 3 feet in front of us. So, our resolution of reality is finer than 80 ms. BTW, research has also concluded that humans have more than one signal processing pathway in the brain, one of which is much faster than the other. The faster pathway becomes active in highly dangerous situations, and involves much less signal processing than the slower pathway.

    When I was a teenager, I once rode my moped along a road in a 55 mph zone. I made a left turn and heard tires screeching on the pavement behind me. I looked down and saw the front bumper of a dark green car with chrome trim about 3 feet from my left side. I estimated in that moment that the vehicle was traveling about 35 mph. I looked back up and felt the muscles in my right arm begin to constrict as I attempted to steer away from the car. Then, I found myself floating in space, in a bright, white light. All of that had to have taken place in little more than 80 ms.

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  • She

    What goes ’round comes back around….so to speak about ‘time’. Is that why the golden rule became our basic value of the universe?

  • Justin

    “the past and future are equally real…”

    Not scientifically proven. Not even remotely proven. Not even any legitimate scientific evidence for it.

    Poor article.

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  • http://web.mac.com/stankerns Stan Kerns

    No matter how well medicine does the odds of being struck by lightning by your 2,000 birthday start to approach 100%

  • Corbett John

    Who said, “Time does not pass. We do.”? Nothing in the universe is stationary – isn’t that right? From the micro to the macro, all things, particles, objects, etc. are in motion. And motion, or sequences of events, of movement and motion, is what gives humans a ‘sense’ of passing time.

  • jqm

    “You and I won’t live forever. But as for our grandkids, I’m not placing any bets.”
    -Of course not. Because as you say…you wouldn’t be around to collect.

  • Mike Martell

    It’s about the wave function collapse, stupid!

  • http://thepeachdesign.com Peach

    Greatest post this week! Great insights also. I always believe that each individual have their own amount of time. If you spent a lot of time sleeping, you will have lesser time than the one who’s awake. I always value time as top priority, more than comfort.

  • http://charles.kissbrothers.com Charles R.Kiss

    I have trouble with Thing number seven, 7.

    It would be hard to quantify the degree to which human consciousness and awareness are orderly; and this multiplied by all observers in the Universe.

    In fact, I wouldn’t doubt that the total entropy of the Universe remains constant, at zero.

    Not only do I find the possibility intriguing, that knowledge and awareness increase proportionally to the increasingly disordered motion of particles in the Universe -and therefore cancel, but the idea the Universe contains any implicit, measurable, or distinct quantity whatsoever, across its entire domain, to me is anathemous.

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  • http://timelessness.co.uk Matt Welcome

    (and thus no ‘Time’ just matter and motion).

    (Following from my entry #24)

    This is a great post, love the serious and not so serious entries, but I think in a way it shows the problem of taking an unchecked assumption as true then running with it.

    This unchecked assumption is that extra to matter and motion (what ever they are, whether they are ‘fundamental’ or ’emergent’ etc) – we seem to have assumed there is ‘also’ another thing called ‘Time’.

    Most serious studiers of the subject will think this assumption is safe because Relativity is clearly a very comprehensive, accurate and useful theory – and it consistently mentions SPACETIME.

    However, if we read Relativity carefully from the start…



    we can see Einstein rapidly assumes that because we can in a sense remember and agree on a ‘temporal’ order of events, that time obviously in some way exists.

    -But if you consider very carefully where 2 people are recollecting and agreeing on some order of events (say things that happened in a basketball game as in ‘Introducing Time, Craig Callender + Ralph Edny) – what they are ACTUALLY doing is looking at ‘the contents of their own minds’, and agreenin that these contents match.

    from this agreement they assume that there is ‘also’ another record created in a ‘place’ or a ‘way’ called ‘the past’.



    And this assumption is taken as a proof that ‘there is at least a past and a temporal order’
    But gootd science is based on awkward questions, and careful analysis comes up with the question ‘if things could ‘just’ exist, move, change and interact ‘now’ (ie with no such thing as time implied or assumed) – would this be enough to mislead us into thinking time existed.

    in other words ‘is there actually a ‘temporal order’ created and stored somewhere some how in the universe or ‘not’ ?

    because if there is a temporal order then there is and if there is not, then there is not. and if we mistakenly think that the contents of our heads prove more than just that matter can move and change, then we may go on to create a ‘persistent illusion’ like ‘time’.


    S0, as i said #24, i think we have to be very careful, and take a step back from asking ‘does time exist, or what is time’ – and instead ask ‘what do we directly observe’ – which is ‘matter and motion’ – then ask ‘would matter and motion be enough to explain all that we observe and attribute to Time’.

    to which, i think rather surprisingly the answer is yes, the universe is full of matter and motion, and also Time-less.

    If you look at relativity you can see that Einstein never proves that ‘the past’ or ‘the future’ exists, it is just assumed after the temporal order is assumed to exist and mean more than it might. And if you look at relativity as if is just beautifully describes how things move, change, and interact ‘now’ you can see it still makes perfect sense.
    But instead of revealing ‘time dilation’ and thus possible ‘time travel’ – relativity only shows that things might change at unexpected ‘rates’, ‘now’. Which doesn’t prove the existence of, or involve any travel in to the ‘past’ or ‘future’.

    Sorry , no time travel , see > http://www.youtube.com/watch?v=PKsfdGI0X-o&t=5m50s

    (Matt Welcome timelessness.co.uk)

  • http://www.theregjoe.blogspot.com/ The Regular Joe

    so until when I have to realize my goals in life?
    can I beat time?

  • Doug


    Who died and left you in charge of time?
    BTW 1.5B heartbeats = a life. Guess you plan on checking out in your mid 30s. Recheck your math.

    Have a good time.

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  • zietho

    Time doesn’t exist, it’s an abstraction…. well it exist’s an abstraction, as an idea. It is not a thing. Show me the thing called time. Show me the empirical evidence of time. Scientists are evidence based when they have evidence, when not, they are as abstract as Terry Pratchet.

  • stanleyvisnovsky

    This is very interesting. People learn something new. Time was perceived differently in the old days than it is now. In the past there was no understanding of time travel. In the future this could be a reality. Thanks to modern physics mankind achieved greatness in science.

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  • Enoch

    thanks everyone for this ‘STONE SOUP’ made of too much philosophical SEMANTICS for seasoning and not enough nutrition from LOGIC. Kuddos to #86 if opinions on this topic were trees in a forest you are barking up the right species. #107 also kuddos, I would guess your I.Q. is around 135 and your mental ability for abstract physics is above the 95th percentile. I invite you both to keep Plato in mind. I believe that his ‘ALLEGORY OF THE CAVE’ can get you to the right tree…. if you can see the enormous clue that he provides. Best Wishes…

  • PJ McCaskill

    Time? A billion heartbeats? Mankind’s short lifespan and the lifespan of a tree……Any questions?

  • james pope

    I hate my life. I wish I could control time. I would fast forward the next 60 years and get this over with. It’s like I’m trapped here. This is all meaningless.

  • Coll

    Biocentric dreams of a creative universe that revolves around what we think ? We have a very very narrow spectrum of existence. A spectrum of existence we can no more fathom than an ameba contemplating the same.

  • Nim

    When you stop to think, don’t forget to start again

  • tom

    You talk of the Big Bang. Credibility goes out the window. The Big Bang has been disproven many times over. Start with Eric Lerner, then visit the Plasma Universe. Physics in the 20th century was riddled with theories driven by mathematics that were not correct. We continue to suffer from that today.

  • Arnold

    Aging is not simply a function of time. Progeria, the premature aging of children, makes them look age to 75-100 years old at age six to eight, clearly demonstrates that physical aging is based on something inherent in our physiology, not simply a function of time. Focusing on that will do more to slow or suspend aging than anything!

  • ApostasyUSA

    This is one of the dumbest things I’ve ever read on the internet. Coming from Discover Mag doesn’t surprise me.

    Time is only a construct of man. It doesn’t not actually exist. It is a tool, like math.

    We will all die one day and concepts of god and time help us ameliorate the uncertainty of what will happen to us when we do.

    Remove us from the universe and time dies with it. All that remains is a constant of change.

  • Funs Way

    The Universe is in constant flux. The only constant is change. Re: #3 Time is merely our perception of this change. Regarding #7 The Big Bang represents contraction (Yin) and entropy is the expansion (Yang) mode.

    Re: # 9 When we shift our awareness/consciousness in meditation (traditional, moving, sound, or laughter meditation) and time appears to “stand still” does our aging process stop? Is there a link between perceived time and longevity? Inquiring minds in the laughter field are inquiring…

  • George Dishman

    Anyone who wants to reject the idea that time is real should first look at the observations by Hulse and Taylor of the binary pulsar system PSR B1913+16. The orbits are decaying at a rate consistent with energy being carried away by gravitational waves, ripples in the curvature of spacetime.

    Although not yet observed (for obvious reasons), modelling of mergers of spinning black holes also shows that they can be propelled through space by a process called “gravitational wave recoil”, ripples in time can act like the reaction mass of a rocket.


    Time still has a few surprises in store for us!

  • Fred

    @Tom 168, you say that “Physics in the 20th century was riddled with theories driven by mathematics that were not correct. We continue to suffer from that today.” OK fine. Just please don’t be hypocritical and use a computer, iphone, mobile phone, GPS, CD player, credit card, microwave oven, radar system, plane, MRI machine, PET scan, etc, ever again, as they are all based on principles of modern mathematical physics. thank you for your co-operation in this matter.

  • B.Z. Gordon

    Does time exist in each dimension independent of time in the other dimensions? If our perception lags our consciousness then no matter what we do or when we do it, by the time it’s realized by others the error in our communication is exponentially relevant. It’s perplexing as it seems that in the perception we are able to experience energy that makes us predict or influence the future even if we appear to do so by accident. Much to ponder.

  • http://blogsnewsreviews.com AstroGremlin

    For a photon, traveling at the speed of light, time in the rest of the Universe is frozen, non-existent. For a human, the past is a memory, the future is a construct, the instant is too short to measure. Time requires motion to be measured and an observer able to remember the past. Time cannot exist without matter, and a very special kind of matter from which consciousness has emerged. Time seems like it might be a construct we impose on the Universe to make sense of our experience.

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  • http://www.perceptionoftime.com Eileen Dight

    This is a remarkable article and blog. I wish I’d attended the conference. ATTITUDE to time has long absorbed my interest. The way a person perceives time reveals their character: how they spend time, fear it, waste, save it and so on. I welcome personal attitudes for a book project.

    We agonize over a young person terminally ill, but when depressed our salvation is that we are not immortal. Between those extremes a thousand philosophies lie. See my website http://www.perceptionoftime.com and comment.

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  • Pierre Savoie

    What’s mind-blowing is that there are not 3 dimensions of space and then time, but the dimensions are hybridized space-time mixed together. If you manage to “sit still,” you are whizzing along time at nearly the speed of light. If you should move, however, your movement “takes away” from your maximum possible time speed, and time starts to slow as per the equations of time-dilation. If you manage to move at 99% of the speed of light, time slows over 7 times because of your movement. 99.9% slows time by over 22 times, and so on. If you could reach the theoretical maximum light-speed (but you can’t), all the possible speed would be consumed and time would stand still.

  • http://crisdelvallelife.blogspot.com/ CoreAn_Crack3rZ

    Nice article. Seems similar to quantum science whatever it is… 😀 Anyways, great article! 😀

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  • ken

    So, time is space. there was a bang and we said look, let’s call this TIME. the bang is still going on(Space) but how? the bang would not ever happen, there was no time before it! Is just would never have been there. in space or time.

  • Scott

    I’m not 100% convinced space exists, let alone time.

  • BlueCollarCritic

    From the perspective of a non-physicist (who loves physics and science )…..

    Time is the comparison between events. The time it takes to write this sentence is the comparison of the typing of the sentence to the number of ticks (seconds) on a clock.

    Time is what allows 3 dimensional entities (us) to experience the events of our reality in a fixed order.

    There is no past or future as far as having happened and yet to be. There is simply time and where we are relative to the experiencing of these ordered events. I experience birth before death and events between these compared to the number of ticks on a clock provide the time (or measurement) of my life.

    Your past and your future already exist and both are based on the choices you’ve already made (as well as others). We may not yet have experienced all of these events that come from our choices but that has more to do with our being 3 dimensional entities then whether or not they have happened.

    It’s hard to properly convey using the written communication of our 3 dimensional existence but I think the above is close.

  • An Atheist

    “Other than creationists”
    A superfluous, incorrect and stupid thing to write.

  • Carl

    The “past” (as a word/concept/term) can be used in relation to what has been found to have occured (the factual) as much as what could have occured (the speculative). And likewise the “future” is used in relation to what remains to be seen, as much as what might take place.

    The past and future may be implicit in the present but the number of possible pasts and futures implied by any given present is either very large or infinite. If the term “reality” is used in relation to both the facts as much as the possible (as is increasingly typical) the term “reality” can become somewhat stretched to the point of being totally ineffective – what does one mean by the word? For example, to say the multiverse is real is to say next to nothing about the multiverse.

    The reason for the word “reality” becoming increasingly ineffective (or defective) is quantum mechanics. In QM the possible and the actual are found to be functionally related yet not equivalent.

  • austin

    im curious. if all creatures experience about 1.5 billion heartbeats shouldnt that mean exercise is in fact decreasing your lifespan by burning up those ticks? and shouldnt increasing your metabolism in fact be like increasing the flame on a candle?

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  • Charles Ferguson

    Most of the posts claiming that time is a human construct and therefore fundamentally nonexistent contain the same error: they conflate the human concept of time with the phenomena itself. After demonstrating that our concept of time is human-created, they seem to imagine they’ve proven that the phenomena this concept seeks to explain must therefore also be artifical.

    This actually doesn’t add anything to the debate, since the only thing it addresses is the half of the question that almost everyone agrees with already.

    The real point – the point the more rigorous posters are attempting to explore – is the nature of the phenomena itself.

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  • RealityWatcher

    Time is an illusion (but a useful distinction tool), can be disassembled, and only requires 2 physical facts: change/motion, and a memory/storing mechanism (take one or both away, and time doesn’t occur for where an observer-knower occurs). Time simply emerges from mutually-required 1) the continuum in motion (if entirely static, nothing would exist, including consciousness/awareness), and 2) our differencing/comparing engine with its stored states (memory). It’s never other than Now, and the past (even 80 milliseconds ago), and imagined futures, is thought or known only now. This puts everything occuring in the universe across a ‘flat screen’ we call “Now”.

    If our current awareness is really 80 milliseconds ago (conscious existence, ‘in the pipeline’ so to speak), yet we physically exist now, then we are doing ‘knowing’ of 2 separate points in time, simultaneously. One can be more unified than that :-) Your knower that’s aware of 2 (or more) time points simultaneously is the state we call Now. Anyone thinking we don’t physically exist right now may have alot of fun wasting alot of words trying to prove that notion.

    Try this PoV/image: If absolutely everything in the universe stopped (ceased motion), there would be no way to detect time, or how much “time” had elapsed once it commenced motion. Of course, if absolutely everything ceased particle motion and force-field/energy flow, and I mean all of the points that make up all of the threads that are vibrating inside of every vibrating superstring that gives detectable effect to everything we call physical and phsical elements, then ‘it all’ would vanish. Motion is required for physical existence, and the apparency of time, therefore motion is more foundational (the truer truth). Motion (at the continuum level) is necessary to be. Time isn’t required to simply “be”.

    The “Rabbit Hole” may seem deep, but there is an understanding where the illusion we call “Time” isn’t a mystery.

  • Rowdy

    I’m no physicist or Mensa member, but here’s my take on things:
    1. Everything comes down to Cause & Effect. Everything is based on the past, and everything effects the future. Everything is both a Cause and an Effect.
    2. The future is set. Free will does exist, but only as an illusion. Every decision you make is actually dependant on Causes from the past. Your frame of mind leading up to the decision is effected by what’s happened to you in the day leading up to it, your past experiences are going to guide you in making any decision, the exact position and angle that you observe external stimulus from, and on and on into factors that none of us would ever believe could be significant enough to make a perceivable difference. Whatever you believe, the fact is that you were always going to make that particular decision at that particular time. You may change your mind 10 seconds later, but you were always going to do that too.
    3. The past and future don’t physically exist. Matter only exists in the present. If time travel is possible, it’s only through non-physical means (I’m only 99.9999999% sure that phychics are all full of shit). You may also be able to create the illusion of time travel to the future by putting your physical body into a temporarily static state, but you’ll never physically be able to wink in and out of existance at different points in time.
    4. There may be some special start and end points to time where they’re just a Cause or just an Effect, but I think it may be more likely that time is circular and everything will just lead us back to the same point again. If there was a big bang to create our universe, then whatever ends it will cause another big bang (so points 1 & 2 still hold).

  • T

    I stopped reading at 1. Time Exists…

    The proof of this is that you can set your alarm clock?!!! Who invented the alarm clock? Mother nature? No, man invented it keep track of the sun. That doesn’t mean time exists. It’s another man made concept, most ignorant humans cant imagine a universe without themselves in it.

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  • http://johnklinekurtz.blogspot.com John K.

    In #1., the author stated “thank goodness”. Some might rather say “thank God” that time is not completely chaotic. For the brave among you, here is a related article that might bring some insight to the topic. Evolution Ex Nihilo.

  • Lingjie

    EM wave(photon) have speed c which combines time and space(in 3D! Magnetic field direction,Electric field direction, and travel direction). Photon is the most/smallest fundamental particle. May Time come from that..?

  • http://timelessness.co.uk Matt Welcome

    I think #196 T, can be shown to be correct, And INSPIRED me to write up the following thoughts,

    (related VIDEO ‘Do things ‘take time’ to move, or just move ?’
    >> http://www.youtube.com/watch?v=WV3VjsY03Hk&t=1m4s)

    PAGE >> https://sites.google.com/site/abriefhistoryoftimelessness/mathematics/what-do-clocks-measure
    (with respect) Sean’s first assumption ‘Time exists’ … setting alarm clocks proves it – can be seriously and logically questioned, e.g…

    – The ability to create something we might call an alarm ‘clock’ may seem to confirm the existence and nature of ‘time – IF – we start with the assumption time exists*, but an ‘alarm clock’ does not necessarily prove the existence of ‘Time’ (with its flow, direction, Past and Future etc.)

    (*just as if we watch a mind reading show with the ‘assumption’ that mind reading exists, are assumption may ‘seem to be confirmed’ – but we may still actually be mistaken).


    Consider making a large heavy mass, free to rotate on good bearings. We attach a small ‘arm’ so it sticks out from the mass at one location.

    Then we set the mass spinning… any steady speed will do, but a speed matching the speed at which the Earth happens to rotate will be simplest… ( only for us here on Earth =)

    With this set up one could place a ‘bell’ at any point around the spinning object, such that the protruding arm will strike and ring the bell where the two meet.

    Now if for simplicity we do set the mas to spin at the same rate the Earth happens to be spinning at, then in Time terms, putting the bell 15 degrees on from where the protruding arm is will effectively make an alarm clock, which is set to go off in ‘one hour’.

    But look from fundamentals what the set up actually shows and does not show.

    -the spinning mass shows that objects can exist, rotate, and have inertia.

    -that energy can be put into an object, and

    -that energy is needed for objects to move

    -the protruding arm shows that a moving thing can be heading for other things, (the bell in this case)

    But the device does not prove that….

    -as things move they leave or create a ‘temporal past’ behind them, or that

    -ahead of moving things there is a ‘temporal future’, or that

    -moving things head into a temporal future, or that

    -a temporal future is constantly arriving, passing through an infinitely thin present, and into a ‘past’.

    -or that, as well as ‘energy’ things also need a thing called ‘time’ to be existing and flowing.

    This section might cause some irritation as you read it, but we should not assume that ‘If we are feeling irritated – this is a scientific proof that our currently held views are correct, and those views that irritate us are incorrect’. (in fact often the opposite is true ‘feeling irritated’ can be a sign that we are not being scientific).

    Further more it is worth considering that the concept of an alarm clock may ‘seem to confirm’ the existence of time – if it is looked at ‘as if time exists’ – but if it is looked at as if ‘just matter and motion exist’ then this simpler* view will also seem to be confirmed.

    note also that ‘seeming to confirm’ an assumption is not the same thing as proving an assumption from first principles, or direct observation.

    *Simpler because it doesn’t call on the existence of an invisible past, invisible future, the ‘unpowered’ flow of an invisible thing called time – through an ‘infinitely thin’ present.

    ( See web link above for DIAGRAM.)

    matt welcome

  • Shane

    Wait, what??

  • da808wiz

    My 12 year old daughter is so inquisitive at times, I begin to wonder about things I had up until that point accepted as fact.

    In the case of the big bang theory, and my limited knowledge of it, my daughter had asked, “What is the big bang theory?” Well, without grabbing numerous texts and scientific journals on the subject, I attempted to explain it in the simplest terms, which coincidentally fit my simple mind.

    As I explained it, I began to wonder about the origin of it all.

    Let me put it simply. I explained there was some huge ball of matter, which somehow exploded, the pieces were sent outward throughout space, and formed the various galaxies. Supposedly the universe is constantly expanding. If we were to build some kind of super-fast spaceship, we would be able to travel far enough past the debris to a point where the universe ends, an eternal blackness of nothingness.

    My question which comes from this rudimentary answer is, “How the h*ck did we come up with this one?” My guess is someone took a telescope and a computer, then progressively more powerful telescopes and computers, and pointed it into outer space, and determined there appears to be a limit to what we can see out there in any infinite direction. The fact that “what we percieve determines what is” is a horrible basis for what is, in my opinion. I get the impression that whomever devised the theory of the big bang have determined that the Earth is the center of the universe. If they have not, I’m guessing SOMEONE is probably wondering where that supposed center is. It must be calculatable taking into account the direction of the various galaxies and particles if such an explosion could occur in the vast matterless vacuum of space billions of years ago and still be in motion from a perfect zero friction environment.

    Funny thing, she also asked about dark matter. Again, armed with my vast knowledge and intellect on the topic, I explained that there are things that exist in the world that cannot be verified light or the reflection of light off it, thus the term dark matter. Not to be confused with the experiments on objects which light is able to bend around, the “cloak of invisibility” experiments of recent history.

    Disclaimer: Lots of sarcasm when discussing the topic of my “intellect”…

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  • CuriousTech

    @BlueCollarCritic (187.) I like that explanation a lot. Time is simply a unit of measurement, and we love to create measurements for everything, so we made a name for this measurement (of relativity) which is simply a counter. Not really the same, but think of a car’s odometer. We’d go twice the distance to reverse it back to zero because it’s simply a counter measuring units of something. I know, bad analogy but there aren’t too many. How about a Watt or Amp hour?

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  • jeff geddes

    How extraordinary you all are with your opinions and conjectures of time!
    In fact no need for Eisteins/Newtons’Hawkins/Dawkins/Hitchins/Hubble’s Uncle tom cobleys billy connonleys …whatever.. what a band of nonsense-makers you all are.
    Time is sinply a man-made invention a clock -face with two hands to keep you all enslaved
    to money-making for survival to keep the elite and mockery democracies in business.
    Time of itself does not exist, simply a process like your age you live/decay/die like all things
    as portrayed in the four seasons. Time is a man-made invisible enslaving master used by
    pleasure seeking deluded aristocrats,politicians, and all the other human ingredients
    required to keep them in business…armies/navies/celebrities/hollywood arsetists.
    Go on tell me my email is not valid!!! hey hey.

  • Mark

    Time does not exist, it’s imaginary. We just think time exists so we can enjoy the present, reminisce about the past or dream about the future.

  • Andrew Rose

    Alphacarey points out that the Billion heart beat rule doesn’t apply to Humans – They claim that Humans reach the billion heart beats point around age 30. What they fail to point out is that human lifespan is no longer bound by the laws and time spans of nature – Keeping ourselves alive through technology and and drugs.

  • Saku

    Saying time doesn’t exist is like saying love doesn’t exist…

  • John Smith

    “It appears therefore more natural to think of physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence.”
    This is exactly the sort of extrapolation from a theory that tends to be thrown away as science moves on – the kind of extrapolation that can’t be verified directly (unlike, say, mass-energy equivalence) and which comes from taking the theory literally when scientific theories are just working models, and may later prove to only approximations to the truth (as, for example, K.E.=0.5mv^2 is an approximation, and becomes inadequate near lightspeed).
    To say of things based on this, “This isn’t completely accepted, but it should be.” is nonsense. It should never be completely accepted by anybody with the slightest experience of science – if you only know one thing about science, let it be the fact that our theories are always liable to change, unless we have observed them directly. We have observed directly (from space) that the earth is round. We definitely haven’t observed directly that the past and the future exist, and we never will unless a time machine is invented.

  • http://timelessness.co.uk Matt Welcome

    to #201 , Shane

    (wait, what ?) …. Which bit =)



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  • David Ian Wilson

    ERROR: as per comment 47, “Part of the “job” of complex structures is to increase entropy,” should read “Part of the “job” of complex structures is to DECREASE entropy.” Living systems produce a localised decrease in entropy at the expense of an overall increase in entropy of the system of which they form a part. Rather like an up slope back eddy in a river flowing downhill.

  • http://Wildblue Slyfox666

    I believe Einstein said “The concepts of past, present and future are all illusions – but persistent ones.”

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  • John

    It is my opinion that time seems to go faster with age due to an unconcious realization of impending doom, or death.

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  • Peter

    I first came across the “billion heartbeats” data in an article by Isaac Asimov, years and years ago. The scaling seems to hold for all mammals except ourselves. Perhaps it was also true for us when our life expectancy was shorter, and it’s only our tendency toward civilization that has allowed our lifespans to more than double the heartbeats allotted to species without MD’s and refrigerated foods.

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  • Big Muck

    Bing Bang why do they keep pushing that
    if there is no beginning and no end
    its to bad we can’t measure it or wrap are small brains
    around it
    I’m sure I have already posted this and will again in the future

  • Big Flava

    I may have missed something, but I’ve read 223 postings, in addition to the article, and I haven’t seen an agreed upon definition of time. So many thoughtful and articulated arguments becoming irrelevant to each other because the fundamental definition of what you’re trying to prove has too many interpretations. I’ve enjoyed reading the thread, but the ‘debate’ is baseless without an agreed upon definition. All this blather about mass, energy, entropy, blah, blah, blah. And 40 years ago when I was a kid, Pluto was a planet. The only thing science proves is what the human race thinks it knows at any given moment in time; pun intended. And no, I don’t want to live without my telephone or cable tv or any other 20th century scientific discovery. But I could. And there’s the rub. The hubris of the scientific community is only surpassed by the volume of s_hit that they don’t know and can’t explain.

  • BobbiZiin

    Time created by Humans to reminds them their vulnerabilities [Me]

  • http://crashex.com A. Granville Fonda

    TIME [Posted 9-11-11]

    We know time not by what it is,
    but by what happens within it.
    “Time will tell,” and it does;
    but it speaks not of itself.
    Only of events, and of memories of events.

    Darwin drew diagrams of a solitary leaf
    as it stirred upward and downward through the day.
    “And doubtless, when swallows come in the spring,
    they act like clocks,” said Descartes.

    Steel columns, heated to redness, in time buckle
    and suddenly lower millions of pounds
    to impact like a pile driver on the floor below,
    which interrupts the fall, but in the interruption,
    amplifies the weight to trillions, and fails.

    Which interrupts the interruption,
    creating a vertical pendulum, a keeper of time,
    accelerating as it collapses.

    Time then continues after, as it had before.
    But never the same.
    For we know time not by what it is,
    but by what happens within it.

    Copyright 2001 Albert G Fonda
    (Written 10/26/01, 8:05 to 8:15 AM, as-is.) (I cried – as much as an engineer can.)

    Darwin and Descartes from Jonathan Weiner, in “Time, Love, Memory” (Knopf, 1999)

    Pile-driver insight from my petroleum engineer son Mark

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  • D

    Interesting idea, a lack of motion and what effect that would have on time. However, it couldn’t happen. Without motion, the sun wouldn’t be able to produce heat or shine, I think. There should cease to be any gravitational pulls anywhere, and…what? A lack of motion would have to inexhorably lead to motion so, I don’t think it’s possible.

    On the past future bit. I like to think of our present selves as being a collection of our past experiences and our future hopes rather than just existing “in the moment”. So, I’d be really interested to read more on our linear understanding of time.

  • http://perceptualcosmology.com tamurphy

    “3. Everyone experiences time differently.”

    It seems to me that the subjective experience of accelerating time with increasing age is a function of the volume of organic remembrance. That is, at an early age, the volume of remembered experience is small relative to what it is at an advanced age. Of course, situationally induced recollection from within this growing pool of remembrance is the behavioral trigger for making this assessment.


  • http://perceptualcosmology.com tamurphy

    Would it not be correct to say that change is fundamental, and time is a perceptual overlay?


  • Fred

    @ Big Flava 224, you say you could live without your telephone and tv. good for you. also, try to live without medicine, vaccines, modern medical technology, vitamin supplements… oh wait… you can’t and neither can your family. as to the rest of your ignorant comment where you refer to energy and mass as “blather”, i won’t waste my time responding.

  • Stormchild

    Is it really mysterious that touching one’s nose and foot “simultaneously” should be experienced as happening at the same time? For electrical impulses (which move at the speed of light) the increased distance is hardly significant, and in any case it seems obvious that we’re not equipped to perceive the resulting microscopic difference in timing (nor are we capable of perfectly synchronizing the act of touching both spots anyway).

    I also don’t believe the 80ms latency applies to all types of experience. Certainly 80ms have not elapsed between the time when I touch my nose and when the sensation is experienced. As a music producer, I know that I can perceive a latency as short as ~20ms when playing keys on a MIDI keyboard (the question of latency comes up when setting the buffer size of software to strike a balance between accurate timing and the increased strain on system resources when lowering it). Professional drummers with a very highly developed sense of timing can perceive even shorter latency values.

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  • http://www.astro.multivax.de:8000/helbig/helbig.html Phillip Helbig

    “there’s a real sense in which time moves more quickly when we’re older.”

    The link points to an article which mentions one of the reasons: when we’re young, we experience more first-time events, more interesting events etc and have more detailed memories, which makes that time seem longer looking back on it. (What the article doesn’t mention is that in the present the trend is reversed: interesting things fly by, and boring things take forever. Since we experience the present just once and always have our memories, it’s probably better this way.) However, there is another effect: for a baby, a year is a lifetime; for a very old person, one year more or less hardly matters. In other words, the older we are, each year corresponds to a smaller fraction of our lives. The first effect explains why it seems that time used to pass more slowly while the second explains why we old folks feel it passing quickly now.

  • http://www.astro.multivax.de:8000/helbig/helbig.html Phillip Helbig

    “10. A lifespan is a billion heartbeats”

    Do the math. In general, true, but for humans, it is significantly more. For parrots as well. Go figure. A billion human heartbeats is only 30 years.

    One might argue that the natural human lifespan is 30 years, and the extra 30–60 are the gift of science. True, but no cigar. Animals in captivity, with fewer dangers, better medical care etc do live longer, but not 3 times longer as their counterparts in the wild.

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  • Tommy

    Sorry Sean, but you are wrong in your comparison of contrast to aquatic life, land-based animals!

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  • Indra Prasad Sharma

    At present time is measured with reference to the Sun being at our Zenith and only the galaxy exist. But if we take a more broader picture of the universe and various other galaxies then we need to shift to make a different reference point to measure various events at a time to follow the history of various activities of various creatures in various galaxies.

  • http://planeetanihmeet.wordpress.com/ Maija Karala

    In contrast to aquatic life, land-based animals, whose vision-based sensory field extends for hundreds of meters, have time to contemplate a variety of actions and pick the best one.
    As a biologist, I do think this is a sadly human-centered view that has not much to do with the actual sensory and cognitive abilities of animals. Because we are vision-based land animals does not mean that being one is compulsory to be intelligent or conscious.

    Firstly, not all land animals have a “vision-based sensory field”, not all of them live in the open ground where such large-scale vision is possible and not all of them are diurnal. Many land animals base their sensory field on smell, sound, echolocation etc. which bring information for consideration just as well as vision.

    And then again, many marine animals are highly visual and/or subsitute their eyesight with long-range echolocation, electroreception or such like.

    And it’s not like an animal has to constantly move forward like a clockwork machine and have to sense things from far away to have time to think before they are right in front of it and decisions have to be made. Animals can stop and take their time to investigate and think, and they often do. With predators, it’s not a good idea, but with pretty much everything else, you don’t need to see (or smell or hear) things from far away to have time in your hands.

  • Funs Way

    and yeppers, it would seem “change is fundamental, and time is a perceptual overlay”. (# 232)

    There is Form and there is Flow. Form creates and limits Flow, Flow creates and limits Form. Time may in fact be our snapshot view of this phenomenon.

    Consider the following:

    The stillness
    in stillness
    is not
    the real stillness.

    Only when
    there is stillness
    in movement
    can the spiritual rhythm appear
    which pervades
    heaven and earth.

    Ts’ai-Ken T’an

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  • Monica Garliceanu

    Ever since I read about the 80 ms lag between things happening and us experiencing them, I’ve had a question in my mind: where does this leave the “quantum mind-body problem”? How can our consciousness cause the collapse of the wave function when by the time we are aware of an event, that event is already in the past?
    It seems to me that, by the time we open the box, the fate of the cat have been already sealed.
    Does anyone have a theory about this?

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  • Funs Way

    Hi Monica,

    Our perception is not limited to our thinking/being in the conscious mind. Intuition is an inherent awareness and we can “know” something without consciously thinking it.

    Actually, how else could one explain that over 5,000 years ago the great Masters understood polarity and many other aspects of Energy without the use of the technology scientists currently use. They sat very still, honed and heightened their awareness.

    Many of us have lost this ability by becoming slaves to our “busy” minds. In doing so, our minds are in the past or future. Can we be fully present? I think with practice, we can have the experience some of the time.




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Cosmic Variance

Random samplings from a universe of ideas.

About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] cosmicvariance.com .


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