The Universe is still expanding. As expected.

By Phil Plait | October 4, 2012 10:31 am

The Universe is getting bigger!

But then, we knew this. We’ve known it for a long time! The reason you know Edwin Hubble’s name at all is because in the 1920s he was critical in figuring out the Universe was expanding. He and many other people did this by looking at a specific kind of star, called Cepheid variables. These stars literally pulsate, getting brighter and dimmer on a regular schedule. As it happens, how much they change in brightness depends on their actual brightness… and that means if you measure how much they change, and how bright they appear in our sky, you can figure out how far away they are. And if they are in other galaxies, then you can tell how far away those galaxies are.

Boom! You can measure the size of the Universe. And more.

Using this method (which I explain in more detail in an earlier post, if you want details), they figured out the Universe was expanding – the farther away a galaxy is, the faster it appears to recede away from us. This is what led to the Big Bang model of the Universe, and essentially all of modern cosmology – the study of the origin, evolution, and properties of the Universe as a whole.

Over the decades, that rate of expansion – called the Hubble Constant – has been measured many different ways. Using Cepheid variables is still a foundation of the work, though, and a new study just released by astronomers using the Spitzer Space Telescope show that the rate of expansion is 74.3 +/- 2.1 kilometers per second per megaparsec. What this means is that a galaxy one megaparsec away (that is, 3.26 million light years) will be moving away from us at 74.3 km/sec. If you double the distance to 2 megaparsecs, a galaxy would be moving away at twice that speed, or 148.6 km/sec.

This study is pretty neat. Spitzer observes in the infrared, which can pass right through interstellar dust. That dust is like a fog, obscuring the visible light from stuff behind it, and it really messes with measuring brightnesses. That has plagued Cepheid studies for years, but Spitzer simply steps around that problem! So this measurement appears to be pretty accurate, more so because they calibrated it using Cepheids in our own galaxy (and one nearby one), and combined it with results from other observatories like WMAP, which can measure other properties of the Universe as well. By doing all this, they’ve produced a very accurate measurement of the Hubble Constant.

I want to be clear here: this new study is more accurate than previous ones, and much more accurate than one done a few years ago using Hubble. However, a study done just last year got the expansion rate to an accuracy of about 3.3%, and that used a combination of Cepheids and Type Ia supernovae – a star that explodes with a measurable and predictable brightness. This new study has an accuracy of just under 3% – an improvement for sure, though not a huge one over last year’s.

Still, this is very cool. That last study got a rate of 73.8 +/- 2.4 km/sec/megaparsec, so they both agree closely within their error margin. In fact, they’re statistically identical (and agree with quite a few other measurements made in the past, too). That’s good! It means we’re really nailing this number down, and that’s further evidence we really do have a pretty good basic understanding of how the Universe is expanding.

There’s still a lot to figure out in cosmology; we don’t know what dark matter is, and about dark energy we know even less. But it’s good that people are looking into other ways to measure basic properties of the Universe. The more we know them, the less we have to worry about them. And it shows that our overall model holds up. The Universe had a beginning, 13.7 billion years ago. It was small then, but it’s been expanding ever since, and in fact is expanding faster every day. We are a small part of it – in fact, our matter is a small part of all the matter (that dark stuff dominates by a lot) and even that is a small part of the stuff that makes up the Universe (dark energy wins that round).

And as amazing as all that is, I am even more astonished by the fact that we can know any of this at all! The Universe obeys rules, and by doing so reveals those rules to us. We just have to be smart enough to investigate them and learn about them.

And we are that smart.

Image credits: Image credit: NASA/JPL-Caltech; CBS


Related Posts:

- The Universe is expanding at 73.8 +/- 2.4 km/sec/megaparsec! So there.
- The Universe is expanding at 74.2 km/sec/Mpc
- Wait a sec. How big is the Universe again?
- The Universe is 13.73 +/- .12 billion years old!

CATEGORIZED UNDER: Astronomy

Comments (89)

Links to this Post

  1. El Universo sigue expandiéndose | Matuk.com | October 7, 2012
  1. Robin

    I saw Lawrence Krauss speak when I was an undergrad, and at the time he made statement that rocked my physical world with its perspective. He said because of the expansion of the universe and the relative speed between Earth and other bodies in the universe, the number of things we can know decreases with every passing day. Light never makes it here from bodies that are far enough away to have a relative speed greater than c. It’s sad knowing that even if it’s only by a little bit, our pool of potential knowledge grows smaller.

  2. Chris

    Since the universe’s expansion is accelerating, is the Hubble constant really constant? If we were to measurements in a few billion years, would we get the same number?

  3. oldebabe

    ISTM that if the universe is limitless, then one cannot base its size on the galaxies we can still see, or their speed away from our galaxy. So, the universe itself isn’t expanding, it’s just that we are getting more clever about finding and estimating what galaxies are doing…???

  4. Doc

    Ok, something’s bugging me here.

    The objects that are farther away are moving away faster – I can cope with that. But, seeing as the light we’re using to measure the red shift is actually light that left the object X years ago, doesn’t that mean that it *was* moving faster than nearer objects, but may be moving the same speed or slower now?

    I mean, it would make sense that things were moving faster at a time closer to the big bang than they are now, assuming that gravity or whatever has slowed them down. I assume there’s no good way to know how fast distant objects are *currently* moving away, or is there?

  5. ctj

    poor, poor georges lemaitre.

  6. Fizz

    Hi Phil-
    Back in March 2012, Discover Mag had an article about physicst Julian Barbour. He has a theory that apparently explains what we see in the universe without the need for “inventing” dark matter or dark energy. Basically, Einstein “didn’t go far enough”. It’s an interesting read.
    But, I am curious. As a working astrophysicist, what your thoughts are on this article? Is it possible he’s right? Is the guy a crackpot (if so, why)?
    Thanks!

  7. Dazrin

    “It was small then, but it’s been expanding ever since, and in fact is expanding faster every day.”

    What force is causing the universe to expand faster every day? Or (assuming a roughly spherical universe) is this just because the sphere of the universe is getting larger, so a linear expansion of radius makes the volume go up by a cube power of that?

  8. Bjoern

    @Chris: You are right, the Hubble “constant” is not really constant with respect to time (it’s only constant with respect to space, i. e. it has the same value, no matter in which direction we look). That’s why it’s often called the “Hubble parameter” instead of “Hubble constant”.

    @Doc: ” I assume there’s no good way to know how fast distant objects are *currently* moving away, or is there?”

    Actually, if you do the math, the redshift of galaxies tells us precisely at what speed they are *currently* moving away from us! Counterintuitive, but true.

  9. Regner Trampedach

    Hi Phil,
    Thanks for a great post. One correction, though. It is the period of the Cepheid pulsations which is strongly correlated with their absolute brightness. This is fortunate, since it is much easier to get accurate periods.
    oldebabe @ 3: It doesn’t seem likely that the Universe is infinite, since it has a finite age. It doesn’t have an end to it, however, since it is most likely in the shape of a surface of a sphere (which doesn’t have an edge, but is finite) – except it is a 3D surface of a 4D sphere…
    We don’t know how big the Universe is – we can only see as far as the travel time of light allows us. We can, however, still observe how the size of the Universe is changing, by observing the galaxies moving apart from each other.
    I am not sure how you came to the conclusion that the Universe is not expanding and we simply know more about galaxies – that doesn’t make sense to me. Please elaborate.
    Cheers, Regner

  10. Renee Marie Jones

    Generalissimo Francisco Franco is still ….

    Oh. Sorry.

  11. StephenH

    This will probably be a silly question to most commentators, but is it possible to combine this measurement and the previous one to conclude that the expansion of the universe is 74.2 +/- 2.0 km/s/megaparsec, based on the new measurement setting a lower bound of 72.2 and the old measurement setting an upper bound of 76.2? Or is there something more complicated being glazed over, such as a statistical confidence interval (e.g. we’re 99% certain that the true value exists between these error bars)?

  12. Bjoern

    @Dazrin: “What force is causing the universe to expand faster every day?”
    According to the current cosmological model, the negative pressure of dark energy causes this acceleration.

    @Regner Trampedach: “It doesn’t seem likely that the Universe is infinite, since it has a finite age.”
    The second part of the sentence doesn’t follow from the first part – the universe could always have been infinitely in size, from the first moment when it came into existence (the often-heard claim that shortly after the Big Bang, the universe was very small doesn’t really refer to the whole universe, merely to the part of the universe which is observable today).

    “since it is most likely in the shape of a surface of a sphere”
    Why do you think this is most likely? All measurements of the flatness of the universe so far are compatible with all three possibilities: positively curved, no curvature, or negatively curved.

    @Stephen H: Usually one standard deviation is given, i. e. the probability is approximately 70% that the “true” value lies between 72.2 and 76.2.

  13. Brian

    @Bjoern Your statement about redshift really bugged me at first:
    “Actually, if you do the math, the redshift of galaxies tells us precisely at what speed they are *currently* moving away from us! Counterintuitive, but true.”

    I guess you could say that those galaxies aren’t moving away from us, but *we* are moving away from them. I can’t understand being able to measure anything current about a distant galaxy, but I can sure see how we could measure our own movement with respect to those galaxies’ (ancient) light as it is now reaching us. Since it’s really the same thing, I’m okay with that.

    Is that a correct interpretation?

  14. Guilherme

    does this mean that @ 4054 mega parsecs the universe would be expanding faster then light? is that distance our light horizon?

  15. Thomas

    @Bjoern: Actually, if you do the math, the redshift of galaxies tells us precisely at what speed they are *currently* moving away from us! Counterintuitive, but true.

    How is it possible that light that left a galaxy a billion years ago has any information about said galaxy’s current state?

  16. Peter K.

    @#4 I’ve wondered about that myself.

    @#8 I don’t get that at all. Wouldn’t the “speed” result be the same with either the universe currently expanding faster than in the past, or that the universe was expanding faster in the past than now? It seems to me that light from a faster, old galaxy would be slightly blueshifted over time as universal expansion slows down to the present, or that light from a slower, old galaxy would be slightly redshifted over time as universal expansion speeds up to the present, and the end result would not be discernable between the two.

    Saying that the universe is expanding faster in the present because closer light sources appear to be moving slower than farther away light sources is counterintuitive, to me at least.

    I hope I explained what I mean well enough. :)

  17. Bjoern

    @Guilherme: No, that does not mean that at that distance “the universe would be expanding faster than light” (that formulation makes little sense); that does mean that the distance of objects which are currently at that distance to us is increasing at faster than light speed (which does not contradict relativity, BTW).

  18. Ken

    This question will probably cause multiple face palms, but here goes;

    Spacetime can be bent, twisted, compressed, stretched etc. Is it not there fore conceivable that the measurements we use to determine distance, speed, expansion are being skewed by distortions in spacetime that may exist between Earth and what we are measuring against?

    If so, is it possible that it only looks like the expansion of the universe is accelerating when it is not?

    Sorry if this is really a newbie question which has probably been answered before.

  19. Valjean

    The distance between us and our neighbor galaxy is getting smaller. If the universe has already started contracting the light now reaching us from distant galaxies might indicate a red shift from our inward movement rather than their outward movement.

  20. AliCali

    For all those who like this stuff, if you’re in Southern California, please visit Mt. Wilson. You can see the telescope that Hubble worked with to discover the expansion of the universe (and that the Milky Way isn’t the entire universe). So many people who live in Los Angeles don’t even know that the former #1 oberservatory in the world is just up the mountain.

    @ #5 ctj

    “poor, poor georges lemaitre.”

    Georges Lemaître still gets credit for predicting the expansion of the universe using Relativity (even though Alexander Friedmann did a very similar calculation earlier), but Hubble is the one who put the data together (including Slipher from Lowell) and gave observational proof. Similar to how Copernicus thought up the sun-centered universe, but Galileo gave use the obervational proof.

    Lemaître ‘s issue is that he was too humble. He published his paper in an obscure journal. He even visited Mt. Wilson before Hubble’s announcement and never mentioned the possible expansion.

  21. Bob_In_Wales

    Back when I were a lad there were two different ways of measuring H. One gave 50 and the other 100km/s/mpc. We joked you could get the true value by adding them up and dividing by 2 …..

  22. @ Doc (message #4) :

    It’s not just the velocity an object had, relative to us, when the light left us. Spacetime itself is expanding. It’s this expansion of the basic fabric of the universe that imposes the red shift with distance.

    In fact, the relationship between redshift and velocity is different if the velocity is due to cosmological expansion, than if it’s due to an object travelling away from you in the normal sense. General relativity is weird.

  23. The only evidence that we have that space is expanding, that I now of, is the observed redshift of galaxies. Since there are many other possible explanations as to how galactic EM radiation could be redshifted that cannot be readily disproved, therefore “the space is expanding” idea is simply an assumption. Other explanations could be: the diminution of matter; gravitational redshifts (also called Einstein redshifts); an aether drag from particulates such as hypothetical dark matter, Higgs particles, gravitons, etc.; magnetic drag; the Compton effect, etc.

    If this space-is-expanding assumption is somehow shown to be wrong, then the universe would not necessarily be expanding at all and the Big Bang model seemingly would be replaced, if not before then for other reasons.

  24. Alaskan Paul

    I do not understand how things twice as far away are moving at twice the speed relative to something one unit away. Or how everything could be moving away from us at the same speeds, one unit away, in any direction you look. I guess it has to do with everywhere is the center of the universe, which makes this make sense, but then I do not understand how the center could be everywhere.

  25. Renee Marie Jones

    Doc, et al. I am not sure about the details, but it is not really that the objects are moving at ever accellerating velocities but rather that the *space in between* is stretching. It really does not even make sense to talk about the relative velocities of two objects with no common inertial reference frame.

  26. James Evans

    Hate to be Debbie Heat Death Downer here, but I have considerable difficulty finding this particular discovery “cool” rather than a more precise measurement of when a very, very, very cold, dark, silent, empty, dead COSMOLOGICAL BUMMER is headed our way.

    Yes, I understand that even at this rate of accelerated expansion, the ultimate fate of the universe is essentially meaningless to us since it’s many billions and billions of years in the future, and, yes, I am aware that 99.999999999999….% of the universe is inhospitable to life and therefore in an analogously similar depressing state right now, anyway, and, yes, I know I’m projecting very human expectations on the Mighty Uncaring Cosmos, but still…

    Having a better sense of when the lights go out for real EVERYWHERE doesn’t exactly inspire me to raise my glass and join in on a loud, revelatory “Hail, Hail the Void’s All Here!” drinking song or anything.

    I’m jussayin’.

  27. AliCali

    “They say the universe is expanding. That should help ease the traffic.” — Steven Wright

  28. Regner Trampedach

    Bjoern @ 12: So the Universe went from zero extent (non-existing) to infinite extent in no time at the Big Bang. I am sorry, but that defies my sense of logic, physics and conservation of mass, momentum and energy.

    forrest noble @ 23:
    1) The diminution of matter: What is that?
    2) Gravitational redshifts: So the mass of galaxies grows linearly with distance, although the far away galaxies look very similar to close-up ones?
    3) An aether drag from particulates such as hypothetical dark matter: Where did the aether come from? Last time I looked, there didn’t seem to be one… By “particulates” do you mean particles?
    4) Higgs particles: ???
    5) Gravitons: They don’t really do much to light, apart from mediating gravity, resulting in 2).
    6) Magnetic drag: And what does that do to light???
    7) The Compton effect: The wavelength shift from Compton scattering of light on charged particles is much smaller than the cosmic red-shift. Also it is much larger at short wavelengths (X-rays, gamma-rays) than in the in the optical, and non-existent in the infra red. The cosmic red-shift, on the other hand, is pan-chromatic.

    Alaskan Paul @ 24: You are completely right, and you have come to the same conclusion that cosmologists have. That “everywhere is the center of the universe” is a consequence of the Big Bang not being an explosion of matter into an already existing space, but rather an explosion of space, carrying matter with it. The classic analogy of an inflating balloon with dots on it, works pretty well.
    Cheers, Regner

  29. Rick

    @Robin – Not sure I understand this. How would 2 bodies move away from each other at a relative velocity > c? Doesn’t relativity say that can’t happen?

  30. Ben

    Correct me if I’m wrong here. The universe is expanding at a rate of about 74.3 km/sec per megaparsec. but since km and megaparsecs are both measures of distance, they can be factored out of the unit, leaving us with inverse time, or frequency. By my math, since a megaparsec is roughly 3×10^19 km, that gives us a frequency of roughly 2.4×10^-18 Hz, or 2.4 aHz (attohertz). Or put another way, once per 13.2 billion years.

    Is my math right on this? Is this result just a coincidence, or does it make sense that the expansion rate of the universe would match up this closely to the age of the universe? Or am I just spouting nonsense here? I thought i was just screwing around, until 13 billion years came out of it.

  31. James

    Interesting read. I read recently that the speed of light is slowing, dropped by about 400,000km/s in the last century or so. Its been suggested through various calculations that the speed of light was about 8 times what it is now several thousand years ago! This would make for interesting calculations on how far galaxies are away from us and comparative speed.

  32. Jack Nichols

    #4 @Doc – Thank you for bringing that up. I was just discussing that with friends on FB.

    #22 @ Tracer and #25 Renee Great answer to Doc’s (my own question)! ;)

  33. Pablo

    Ben, it seems you just found out it takes 13.2 billion for the universe to get from zero size to today’s size. =) Which is to be expected if the universe’s expansion rate is constant. ;)

    I tried to plug some values in Wolfram Alpha and found out a distance equal to the Earth’s diameter would expand 967 km in one billion years. Does this mean the Earth would be actually larger then?

  34. Thompson

    Ben : it is no coincidence. IMO the Hubble parameter is better thought of as a frequency (or inverse period), since that is its true fundamental unit.

    And it is true that the “expanding universe” is still a hypothetical conclusion; the actual physical measurement data, at this stage, are primarily concerned with light frequencies and wavelengths emitted by particular stars in distant galaxies. Nobody is measuring the intervening space, that is the object purported to be expanding, only the light that traverses the space is measured (i.e. it is a measurement by proxy).

    E.g. if, by some previously unknown mechanism, the intervening space to all the observed galaxies, were twisting or rotating at the frequency of roughly 2.4 aHz, this would also explain the “Hubble parameter” measurements using GR theory.

    There maybe other explanantions that astrophysicists are too unimaginative to comprehend within the current theoretical frameworks also.

  35. Gordon

    James (#31), experiments done in the past half century have shown that the speed of light has been constant since the big bang. The idea of c-decay was brought up by Barry Setterfield in 1981 to “prove” that the Universe was only 6,000 years old. His argument relied on the centuries old measurements of others, made up flights of fancy, and just plain making up data.

  36. Shoe

    @32. Pablo – The expansion of the universe is of spacetime itself. Forces like electroweak and gravity will keep bodies like Earth and galaxies in their relative sizes. The measurement of the speed of expansion is of the universe on the whole. Which is why The Milky Way will crash into Andromeda in 4 billion years, but not crash into BoRG 58 galaxy. The funny thing though, is that we get constantly pelted by meteorites and other space debris daily which builds up over time.

    @31. James – Relativity says that no matter or energy (broadly: information) in the universe can move faster than light. It does not say that spacetime itself cannot. Which is what we are ultimately measuring.

    @30. Ben – While I’m not up to the task to check your math, I think you’ve merely confirmed the age of the universe. Since the expansion moves at a certain rate, and we’ve found that the universe is accelerating then in the future you’d have found it both faster and older, while in the past you would find it both younger and slower. As I said, I can’t confirm your math but that’s what I see from your explanation of the results.

    @29 Rick – Spacetime can move faster than light. As far as the how. There’s the balloon example (put dots on a balloon, blow it up, measure, blow it up some more). There’s one with rubber hose with balls on it (stretch the rope out). You could also get two pieces of graph paper put 25 dots on it. Then get another piece of paper and put 25 dots on that but put them at twice the distance from their neighboring dots, then line up the dots on a piece of paper (take a center dot for example), then try using a different dot (near a corner for example).

    @24 Robin – See Above.

    @23 Forrest Noble – Everything you stated in your “yeah but!” has been:
    A) Compensated for and well documented.
    B) Proven to not exist.
    C) Not proven to exist.
    D) Has no effect on the scales of the study.
    The only evidence we have is careful measurements, mathematics, and observed data for the last 90 or so years that has not only confirmed, but has refined our understanding of the degree at which the universe is expanding. Your fluff won’t change what has happened and what is happening. And even if the Big Bang is an incorrect theory (which isn’t of the topic, the topic is the expansion of the universe), then so what? I know, I know. I can smell the creationist troll within you, but please, there’s a place to peddle your wares, but it’s not here.

    Look at me still talking when there’s science to do. When I look out there, it makes me GLaD I’m not you. I’ve experiments to run, there is research to be done.

  37. whatever

    “the rate of expansion is 74.3 +/- 2.1 kilometers per second per megaparsec. What this means is that a galaxy one megaparsec away (that is, 3.26 million light years) will be moving away from us at 74.3 km/sec. If you double the distance to 2 megaparsecs, a galaxy would be moving away at twice that speed, or 148.6 km/sec. ”

    This is misleading, and condensed down so as to hide the absolute rate of expansion.
    The radius of our universe is estimated to be about 46 billion light years, so dividing this by one megaparsecs = 14110.49 megaparsecs from the center point of the galaxy, assuming we’re at the middle part of this expanse, or ~7055.25 megaparsecs from center, we’re actually traveling at 7055.25 * 74.3km/sec are we not, which is about 524205.075 km / sec.

    Speed of light is 299 792 458 m / s or 299792.458 km/s so we’re going faster that the speed of light, conservatively!, yeah, who cares. Why bother posting these crappy magazine style science releases that most of us don’t understand, and sadly that the Scientists themselves don’t even understand…

  38. Sam

    @whatever: all objects appear to be at the center of expansion.

    So the excelleration of expansion is because dark energy is slowing gaining more influence as gravity gradually has less influence over the expanding forces?

    @ Pablo: the Earth’s diameter wouldn’t appear to have expanded because our rulers are also expanding. Even now you are expanding away from your computer at the rate calculated.
    @Ben and Alaskan Paul: km/sec is the rate of speed, per megaparsec is the area of space for that rate. The further you look the faster the rate of expansion is because all things are expanding from eachother. It’s like someone throwing a tennis ball forward while they’re running away from someone standing still… The ball has it’s own rate of speed from the runner but an even greater rate of speed from the person standing still.

  39. Alejandro

    when looking at distance galaxies we are also looking at light created in a distant past. Is it possible that as you look back in time, the older the time the “less energetic”, so we see them “red shifted”? or in wave terms, the speed of light was faster at that time, and so were the wavelenghts longer for the same quantum of light?
    Not sure if I´m making any sense with these “alternate interpretations” of the observed redshift of distant objects in space.

    BTW, this article is quite old, has their observations been confirmed wrong already: http://discovermagazine.com/1993/apr/manstopsuniverse206

  40. @sci_tek

    #22 tracer- interesting concept; but are you saying that space & time are one and the same, and that because time ‘is marching on’, ie, expanding, so is the Universe? hmm interesting..
    #4 Doc- ’tis what I have been saying for years. The data used to determine expansion is X Billions of years old. It tells us what was happening THEN, not what is happening now. For all we know the Universe has reached its limit, experienced a ‘bounce’ and is now contracting. Another thing that bothers me is that longer wavelengths of light red and infra red in particular, are more resistant to scattering, so if ‘red shift’ enters into the equation, wouldn’t that skew the conclusion of how fast the Universe is expanding?

  41. me

    @37
    You’re defining the edge of the universe 14110 megaparsecs from the galactic center. That number would be better described as the radius of the observable universe, and measured from earth, not the center of the our Milky Way galaxy. We assume that we can see equally well in all directions, so that puts Earth in the middle of what we can see. It’s not a particularly notable place, but it is the de facto center of this frame of reference.

    Anyway, then you say we’re in the middle part of this expanse at 7055 megaparsecs from center. How did we suddenly get there? You just divided by 2 for some reason. We are not 7055 megaparsecs away from the center of the galaxy. We are more like 8 kpc.

    Are you confusing the terms “galaxy” and “universe”? It’s hard to tell. We are also not 7055 megaparsecs away from the center of the observable universe, either. Coincidentally, we are right at the very center. Think about it.

    If you take some bread dough and put raisins in it, when the dough rises all the raisins move away from each other. No matter which raisin you are on, let’s say the rate of expansion is 74.3 +/- 2.1 kilometers per second per megaparsec. They are all at the center of their own frame of reference, hence the term “relativity”. To each of them, they are stationary and all the others are moving away, and the farther ones receding faster.

    Now, what if the bread dough was infinite? Wouldn’t it mean that, in fact, some very distant raisins were moving away from your raisin faster than light? Ponder the paradox! Does that mean “we’re going faster than the speed of light”? And if the dough is infinite, does it even matter what the rate of acceleration is? What if it were very slow, isn’t some raisin really far away still receding faster than light? Wouldn’t that still make it outside the observable raisin bread?

    Yes. And Einstein’s Special Theory of Raisin Bread allows for light speed to be exceeded provided the bread dough *itself* is expanding. It’s just another relativity paradox. You can look it all up in your grandma’s old cook book if you really want to learn something, there’s no need to be such a jerk about it.

    The amazing thing is, scientists like Phil Plait don’t just pull numbers out of their asses to sound smart, they actually study the real universe, have learned some amazing things about it, and will sometimes tell us without charging us for it. Thank you, Phil.

    “… science releases that most of us don’t understand” You are right about this.

  42. jcm

    Paper available on arXiv: A Mid-Infrared Calibration of the Hubble Constant (arXiv:1208.3281 [astro-ph.CO])

  43. Jossarian

    Well, I just want to warn you that in this study there is an assumption that redshifts are due to Doppler effect. Edwin Hubble himself saw different explanation of this effect:
    http://arxiv.org/PS_cache/arxiv/pdf/1107/1107.2485v2.pdf

    He got idea of ‘Tired Light’ effect:
    http://en.wikipedia.org/wiki/Tired_light

    This study only proves that Cepheids and Type Ia supernovae distance measurements based on their bightness is proportional to their redshifts. Study doesn’t prove that there is any expansion at all…


  44. The universe itself keeps on expanding and expanding
    In all of the directions it can whizz
    As fast as it can go, the speed of light, you know
    Twelve million miles a minute and that’s the fastest speed there is

    So remember, when you’re feeling very small and insecure
    How amazingly unlikely is your birth
    And pray that there’s intelligent life somewhere up in space
    ‘Cause there’s bugger all down here on Earth

    /obligatory

  45. @6 Fizz: Hi Phil-
    Back in March 2012, Discover Mag had an article about physicst Julian Barbour. He has a theory that apparently explains what we see in the universe without the need for “inventing” dark matter or dark energy. Basically, Einstein “didn’t go far enough”. It’s an interesting read.
    But, I am curious. As a working astrophysicist, what your thoughts are on this article? Is it possible he’s right? Is the guy a crackpot (if so, why)?
    Thanks!

    Interesting! Thankfully, the article is online, if anyone wants to take a look. You can find it here.
    ( http://discovermagazine.com/2012/mar/09-is-einsteins-greatest-work-wrong-didnt-go-far )

    ps: Really? Discovermagazine.com puts links to its own site into moderation? Sheesh! :P

  46. Robin

    @ Whatever (37):

    You’ve missed an important point: the expansion of space is not confined by c.

  47. Robin

    @Regner (#28):

    Unfortunately the physics we have is unable to describe what happened in the first 10^-43 seconds of the Universe’s existence, so physics and the conservation of mass may not have applied during that period…..or may have been different.

  48. Messier Tidy Upper

    @ 40. Joseph G :

    Ah yes the classics – cheers! :-)

    http://www.youtube.com/watch?v=vIy76M-4txo&feature=related

    Very minor NSFW language warning right at the end of that clip. btw.

    Monty Python for those (very few?) who don’t already know. Figures may be slightly out of date – & textually updated here – but still pretty impressive.

  49. Bjoern

    @ Regner Trampedach:

    Do you really claim that models of the universe which assume it to be infinitely large make no sense? Well, try discussing that with all the cosmologists in the world, because such models have been studied and used for several decades now…

    “So the Universe went from zero extent (non-existing) to infinite extent in no time at the Big Bang.”

    Well, since time started with the Big Bang, it makes little sense to compare the state after the Big Bang with the state “before”…

    ” I am sorry, but that defies my sense of logic, physics and conservation of mass, momentum and energy.”

    Even if we granted that comparing the states afterswards and before made sense:
    1) Mass isn’t conserved on its own (see special relativity).
    2) I don’t see how this contradicts conservation of momentum.
    3) (Total) Energy isn’t conserved in General Relativity in all circumstances.
    http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html
    http://blogs.discovermagazine.com/cosmicvariance/2010/02/22/energy-is-not-conserved/

  50. noen

    Wait… what??? We now have red shift denialists?

  51. Bjoern

    @Thompson:

    E.g. if, by some previously unknown mechanism, the intervening space to all the observed galaxies, were twisting or rotating at the frequency of roughly 2.4 aHz, this would also explain the “Hubble parameter” measurements using GR theory.

    Really? Show your math, please.

  52. Bjoern

    @forrest noble:

    The only evidence that we have that space is expanding, that I now of, is the observed redshift of galaxies.

    The crucial part here is “that I now [sic!] of”. Your ignorance of lots of evidence does not mean that that evidence does not exist…

    Some other pieces of evidence for the expansion are:
    1) time dilation in supernova brightness curves
    2) higher temperature of the CMBR at large distances (and hence earlier times)
    3) Tolman tests
    4) larger density of (dark) matter at large distances (and hence earlier times)
    That’s just four things which come to my mind immediately; doing a bit of research would reveal several more…

    Since there are many other possible explanations as to how galactic EM radiation could be redshifted that cannot be readily disproved, therefore “the space is expanding” idea is simply an assumption. Other explanations could be: the diminution of matter; gravitational redshifts (also called Einstein redshifts); an aether drag from particulates such as hypothetical dark matter, Higgs particles, gravitons, etc.; magnetic drag; the Compton effect, etc.

    As others already have pointed out: all these “other explanations” make no sense, or have already been disproven.

  53. Bjoern

    @Ben:

    Is this result just a coincidence, or does it make sense that the expansion rate of the universe would match up this closely to the age of the universe?

    That the rate is of the same order of magnitude than the inverse of the age of the universe is no coincidence; that the two values agree with each other this closely is indeed a coincidence.

  54. Bjoern

    @whatever:

    This is misleading, and condensed down so as to hide the absolute rate of expansion.

    What is “the absolute rate of expansion” supposed to mean?

    The radius of our universe is estimated to be about 46 billion light years, …

    You forgot to add “at least”. That’s a lower bound, not a measurement of the real size.

    …so dividing this by one megaparsecs = 14110.49 megaparsecs from the center point of the galaxy,

    Huh? That doesn’t make much sense. What distance are you computing here? The distance from the center point of our galaxy to the “edge” of the universe, or what??? Hint: the universe has no edge, so this makes no sense.

    …assuming we’re at the middle part of this expanse…

    The universe has no “middle part”, so the rest of your calculation makes even less sense.

    …or ~7055.25 megaparsecs from center, we’re actually traveling at 7055.25 * 74.3km/sec are we not, which is about 524205.075 km / sec.

    Err, no . That would be the speed at which the distance of the edge of the universe to us (if it existed) increased, not our speed (with respect to what?).

    Speed of light is 299 792 458 m / s or 299792.458 km/s so we’re going faster that the speed of light, conservatively!

    It has already been pointed out in several comments before yours that speeds greater than light speed are no problem here, because we are not talking about objects moving through space, but about space itself expanding. Did you miss all those comments deliberately…?

    Why bother posting these crappy magazine style science releases that most of us don’t understand, and sadly that the Scientists themselves don’t even understand…

    I recommend reading up on the Dunning-Kruger effect.

  55. Bjoern

    @Sam:

    So the excelleration of expansion is because dark energy is slowing gaining more influence as gravity gradually has less influence over the expanding forces?

    The gravity of matter (both normal and dark) decelerates the expansion, the gravity (or rather the negative pressure) of dark energy accelerates it. Since the density of matter goes down with time, but the density of dark energy stays constant, dark energy wins out in the end.

    the Earth’s diameter wouldn’t appear to have expanded because our rulers are also expanding. Even now you are expanding away from your computer at the rate calculated.

    That’s simply wrong. Bound objects like the Earth, rulers etc. aren’t expanding.

    km/sec is the rate of speed,

    Actually, that’s a speed, not a “rate of speed”. I don’t understand what “rate of speed” is even supposed to mean!

    per megaparsec is the area of space for that rate

    And what is that supposed to mean???

    It’s like someone throwing a tennis ball forward while they’re running away from someone standing still… The ball has it’s own rate of speed from the runner but an even greater rate of speed from the person standing still.

    That’s right (if you replace “rate of speed” with “speed”) – but what has that to do with cosmological expansion?

  56. Bjoern

    @Alejandro:

    when looking at distance galaxies we are also looking at light created in a distant past. Is it possible that as you look back in time, the older the time the “less energetic”, so we see them “red shifted”?

    Sorry, I don’t understand what this “less energetic” is supposed to mean. Do you suggest that the atomic energy levels were different back then? That could only work if the constants of nature were different back then, and we have good evidence that they weren’t.

    or in wave terms, the speed of light was faster at that time, and so were the wavelenghts longer for the same quantum of light?

    Same answer: we have good evidence that the constants of nature (including light speed) have not changed in the meantime.

    BTW, this article is quite old, has their observations been confirmed wrong already:

    Oh, Tifft’s quantized redshifts. Yes, that claim has long been shown to be wrong. Shall I dig up some references?

  57. Bjoern

    @sci_tek:

    ’tis what I have been saying for years. The data used to determine expansion is X Billions of years old. It tells us what was happening THEN, not what is happening now. For all we know the Universe has reached its limit, experienced a ‘bounce’ and is now contracting.

    Well, we have observations spanning about 13 billion years, not only at one fixed time. And during all those billion years, the universe has been expanding, following a curve which can easily be described by General Relativity. What reason do you have to suppose that this behaviour has suddenly changed in recent years? What reason do you have to suppose that suddenly, General Relativity isn’t right anymore?

    Another thing that bothers me is that longer wavelengths of light red and infra red in particular, are more resistant to scattering, so if ‘red shift’ enters into the equation, wouldn’t that skew the conclusion of how fast the Universe is expanding?

    What has “resistance to scattering” to do with redshift?

  58. Bjoern

    @Jossarian:

    Well, I just want to warn you that in this study there is an assumption that redshifts are due to Doppler effect.

    Please point out where exactly the study makes that assumption. (hint: it doesn’t)

    Edwin Hubble himself saw different explanation of this effect: …He got idea of ‘Tired Light’ effect:

    Thanks for quoting the Wiki article on tired light – but did you read it yourself…? Already in the introduction we find this sentence: “Despite periodic re-examination of the concept, tired light has not been supported by observational tests…”

    Study doesn’t prove that there is any expansion at all…

    Hint: Observational and experimental science isn’t about “proof”, it’s about evidence. And the results are indeed evidence for expansion.

  59. “That’s good! It means we’re really nailing this number down, and that’s further evidence we really do have a pretty good basic understanding of how the Universe is expanding.”

    Yes, we have come a long way. At a conference in 1995, Bill Press quipped: Someone knows the Hubble constant to 1%. We just don’t know who that person is.

    “Since the universe’s expansion is accelerating, is the Hubble constant really constant? If we were to measurements in a few billion years, would we get the same number?”

    No, and no. I know it’s confusing, but the Hubble constant is not called the Hubble constant because it is constant in time. It is a constant in the sense of a constant of proportionality. (The cosmological constant, in contrast, is constant in time, though the normalized cosmological constant (usually denoted by a lower-case lambda) is not since it is normalized with the Hubble constant.) In general, all the cosmological parameters change with time, even if the universe is not accelerating.

    @#4: Yes, it is possible. If you know the cosmological parameters you can calculate all this from the redshift of the object. All possibilities exist, depending on the expansion history of the universe.

    @#6: Julian Barbour is certainly not a crackpot, though some of his ideas are outside the mainstream. He has also never had an academic position. At a conference in June celebrating 100 years after Einstein was in Prague, he was the first speaker, so he is certainly respected by the community.

    @#7: The cosmological constant causes the expansion to speed up. Without it, gravity would slow it down.

    @#9: A beginning in time does not imply a finite universe, though it does imply a finite observable universe.

    @#30&34: Yes and no. The inverse of the Hubble constant is the Hubble time. This is the age of the universe if there is no acceleration or deceleration. However, this is not our universe. It turns out that early deceleration and later acceleration cancel out, so that the fact that the age of the universe is equal to the Hubble time is a coincidence. What is more, it is difficult to explain away, since they were never the same and the past and will never be the same in the future. There is a paper by Geraint Lewis on this. The question is whether we should worry about it. It is like the fact that the Sun and the Moon have the same angular size. If we worry about one of these things, must we worry about the other one?

  60. Bob

    Phil;

    You stated that the earlier measurement uncertainty was +/- 3.3%, and the uncertainty of the most recent measurement is slightly less than 3%, and that this improvement is not a huge on. I disagree. The actual uncertainty of the recent measurement is +/- 2.826%, which to most would seem to be just an improvement of slightly less than 0.5%. In actuality, it is an improvement of just under 14.5%. As a former metrologist (if there is such a thing), I find this to be a very significant improvement.

  61. Teacher Al

    This is the coolest discussion of these questions that I have encountered. I’m a math-phobe and I live in a Newtonian Universe so it’s nifty to see that people can discuss this in a manner that I can sort of grasp. Bravo to the bloggers! And Phil.

  62. Jess Tauber

    Everyone just takes the cosmologist’s interpretation of an expanding universe at face value. Pretty much everyone just balks at the inverse perspective of matter and energy shrinking in scale (which increases the size of forces and oomph, not reducing). Quantum physics depends on there being a bottom line to radiating away energy, as one would see in macro-scale systems. But if the matter itself were shrinking this would be unnecessary. Every time an electron would infinitesimally fall a little closer towards the nucleus, the latter itself would by shrinking pull away from the electron. If all coordinated the electron, ultimately, could never reach it- the nucleus just keeps moving the bar, as it were. Or think of Lucy and Charlie Brown, with his football.

    If matter shrinks in scale, then any energy quanta produced today would have a different wavelength than that produced in the distant past, when the atoms were bigger. You get the same results here as with Hubble Expansion, except no need for some gigantic mysterious Dark Energy blowing up the scale of the entire Universe- instead we as experiencers made of shrinking matter have an altered perspective, the reverse of that of grown children who remember their childhood homes as being bigger.

    As for gravity, we would have to alter our perception of that as well- if matter/energy scales get smaller, what would need to happen there to make our observations consistent with the hypothesis? And what about the Higgs boson? There may be some relationship between basic quantum spin and dimensional engagement in space and time (and other dimensions as in String Theory). Could spin-1/2 particles which ideally are spatially point particles (follow the numerator!) be falling towards spin-0/2 Higgs, thus CAUSING the supposed shrinkage? And being closer spinwise than spin-2/2 bosons, the fermion fall might be faster, leading to a mismatch. By the same crazy logic gravitons with spin-4/2 would be much less affected. Any purported spin-3/2 units would be affected a little more.

    The opposite effect, all relative of course, would be expansion caused by gravitons, felt most by 3/2, less by 2/2, still less by 1/2 and least by any 0/2 particles. Being central in the scheme, the 2/2- spin bosons would be least affected in either direction- perhaps why C is constant.

  63. Bjoern

    @Jess Tauber: Nice armchair musings – unfortunately all on a qualitative level. Please show your math.

  64. A relativistic universe has four distinct distances: luminosity (inverse square), angular diameter, parallax, and proper motion. No two of them need agree to maintain consistency.

  65. Al is right, except there are more. There is the proper distance (both at the time of emission and at the time of reception; for the other distances, the time is fixed by the definition) and the speed of light multiplied by the light-travel time. In general, all can have different values.

  66. Valjean

    Has any Nobel Prize award ever been given for something that was later proven to be wrong…such as an accelerating universe?

  67. Robin

    @ @Sci_tek (#40):

    I’m not sure what you mean with respect to scattering and red-shift. If you’re wondering about scatterings possible effects on apparent frequency………scattering doesn’t change the apparent frequency of light to an observer. 550nm light incident on a camera sensor is still the same hue of green whether it’s incident at 0° or 45°.

    If you’re wondering if infrared light scattered from other sources are affecting the measurement of red-shift form a specific galaxy, very little of such scattered light will be included in the image produced. Further given that so much of the Universe is empty, comparatively little light of a given frequency will be scattered into the telescope. You also have to keep in mind that the fields of view of the telescopes used are very small, which further limits the amount of scattered light that is imaged.

  68. Valjean

    Flight of Fancy? The beginning event crystallized what there was into points of compressed space surrounded by stretched space the latter pulling between any two of the former…attraction, aka: gravity. From there all else is configurations of the two energies. The simplest foundations supports the most complex constructions and nothing could be more simple than two energies, equal and opposite in every aspect.

  69. Entropy

    @Valjean

    I think the Nobel Prize given out for lobotomy might be considered one that was awarded for a procedure later proven wrong. That’s the only one that I can think of that might fit that description.

    Medicine Prize, 1949: http://en.wikipedia.org/wiki/Lobotomy

  70. oldebabe

    @9. Regner. My thought and question: The big bang had to initially happen and spread into something, as there, apparently, is no such thing as nothing… So all we can at present measure as to the size of the `universe’ is the extent to which we can see, i.e. to the galaxies’ end. Whether or not the galaxies are actually moving away from each other, expanding into space, etc., the farther/better we see them, the bigger the area of the `universe’ seems to get. But perhaps it (space) is there to begin with, rather than seeming to appear in time as needed to expand or contract to suit the extent of the galaxies?

    You asked.

  71. Bruce W. Morlan

    @12. Bjoern (and others) refer to dark energy as being necessary to explain the accelerating expansion. I have wondered if the shell theorem and the associated ability to interchanging the order of summation usually taught in elementary physics courses misleads us at large distances. Specifically, I am asking what the effect of a discretized space (think Planck units) is on that interchange? If the force between two particles drops below some minimum (if the computed curvature of space is less than a planck distance) then the two widely separated particles become invisible to each other in the gravity metric, and as such, would no longer slow the expansion of space between those particles. We would then see that at some distance galaxies are essentially no longer gravitationally bound to each other. Of course, locally the interchange is still computationally correct because the individual terms do not drop to 0.

    The usual answer I hear when I ask this is “gravitons” … because exchanging particles rather than force alone gets around the distance law, but I am not so sure of that, seeing as we do have to explain the accelerating expansion.

  72. Bjoern

    @Bruce:

    We would then see that at some distance galaxies are essentially no longer gravitationally bound to each other.

    And how would that lead to an accelerated expansion…?

  73. Valjean

    The distance between us and our neighboring galaxy is diminishing, not increasing. What if the expansion has reversed and the red shift from distant entities is from our contraction movement “inward” relative to the energy frequencies just now reaching us from those distant entities? Could the oft repeated “We used to think…” be involved?

  74. Bjoern

    @Valjean:

    The distance between us and our neighboring galaxy is diminishing, not increasing.

    As is to be expected – on such small scales, local gravity dominates the global expansion.

    What if the expansion has reversed…

    In other words, what if General Relativity and/or thousands of observations are wrong?

    …and the red shift from distant entities is from our contraction movement “inward” relative to the energy frequencies just now reaching us from those distant entities?

    What is “inward” supposed to mean here?

    And what is “energy frequencies” supposed to mean?

  75. Valjean

    Bjoern…”Inward”. Heading back to where the expansion started. “Energy frequencies”. Light is an energy frequency, whether shifted or received as sent. “Every possibility should be considered” is a fundamental theme of science and many of today’s conclusions contradicted accepted conclusions of the day, some long held, when first suggested. I suggest a different prism to interpret what we detect…even for interpreting those thousands of observations already made…interpretations that contradicted contemporary thought of the day…hence, “We used to think…” being so common.

    Does relativity apply in an expanding universe, but not necessarily so in an accelerating universe, or a contracting universe? Many suggest different values in different parts of this or
    other universes. Are you saying alternatives should never be considered?

  76. Robin

    @VAljean (#76):

    “Energy frequencies” isn’t a useful term. Light is an energy transport mechanism but is not energy itself. It’s an electro-magnetic pheonomena, it is an electro-magnetic wave…..or it’s a particle. Which you choose depends on the analysis. No matter…..you represent light with an electro magnetic field function. The energy in that field is roughly the value of the electromagnetic field squared and than integrated over the volume at which your looking.

    If space were contracting the light would blue shift, not red shift.

  77. Valjean

    Robin. It would be a red shift for the light that has been traveling from afar and just now reaching us and we are moving in the same direction it is. The universe could even be pulsing (like a jellyfish) where some portions are contracting while other portions are expanding. Waves and particles both have frequencies of impact on whatever they meet. Energy frequencies is a useful term in that regard. We give serious consideration to a multi-universe, flapping branes and vibrating miniscule strings with countless dimensions, etc. I see nothing wrong with proposing what I have suggested for consideration rather than summary dismissal. Relativity contradicted many long held conclusions of the day.

  78. Valjean

    Here’s another thing to dismiss. Attraction is present between things and its strength between any two things varies with distance. If the attraction strength variation of an orbiting sub-atomic particle is in the frequency range of light, visible or otherwise, it will be detected as light by a receptor sensitive to such. If its motion is not like that it will still attract but not be seen as the other is…dark matter…same stuff, different motion.

  79. Robin

    If the Universe were contracting, light wavelengths from far stars would be shortened in the same way that light from far stars has it’s wavelength expanded.

    I have no idea what you mean by “frequencies of impact”. It makes absolutely no sense in terms of either the particle nature nor the wave nature of the electromagnetic spectrum. Likewise I have no idea what you mean by energy frequencies. Again, it makes no sense in terms of the particle and wave natures of the EM spectrum. There is an energy associated with an EM wave’s frequency, but that doesn’t say that energy has a frequency In fact, under the wave model of EM, the energy incident on an observation plane of a wave of a given frequency is constant. Go ahead and do the calculations to get the energy of an EM wave or field. You’ll find that the you square modulus of the wave functions, as required, the frequency term in the complex exponent goes away. Thus, energy in the light coming from a star doesn’t have a frequency. It could have a modulation frequency if the star’s energy energy output is varying with some frequency.

  80. James

    Gordon (#35) I did some research and came across this article in which Physicist Dr Russell Humphreys comments:
    ‘The article on the [CMI] Web site is well balanced.
    http://creation.com/speed-of-light-slowing-down-after-all
    It also shows others thinking along the same lines and that the standard “big bang” theory has a “horizon problem” which can be solved if the speed of light was fast earlier on and slower now. There are other papers for and against, and I am still open to either, or an alternative!
    I would be interested in your thoughts

  81. 31 and 81 James:
    Well, the name of that website to which you link about says it all, doesn’t it??!! “creation.com” – AHEM!!!!!
    The entire “c-decay” concept is utter bovine excrement, concocted by a creatard who began with a desired conclusion – that the Universe is 6000 years old – and tried to fabricate data to prove it. That is NOT how science works, is it?????
    In fact, the only thing the original author actually “proved” is that the accuracy of our measurements of c has improved over time – which is hardly surprising! He shot himself in the foot right at the start, by mentioning the first ever measurement of c, by Ole Romer in 1675… Romer’s method involved light travel times between planets in the Solar System – which therefore, by definition, was strongly dependent on knowing the distances of the planets from the Sun. Those distances were known at that time, only to an accuracy of +/- 2-3%; therefore, it follows that Romer’s determination of c had an uncertainty of several percent. DUH!!!!!! ( It was, nevertheless, a pretty good effort for 1675! )
    In fact, as anyone with any knowledge of the history of astronomy knows, the purpose of the worldwide transit of Venus expeditions in 1761 – 86 years later! – was to refine the measurement of the Sun-Earth distance.
    The author also claimed that, after decreasing exponentially, the value of c “became asymptotic sometime around the 1960s”… Er – right!!!!!!! So by some incredible coincidence, it just happened to become asymptotic, at the very time that we became capable of measuring it to one-part-in-a-billion accuracy. Go figure…

  82. Bjoern

    @Valjean:

    ”Inward”. Heading back to where the expansion started.

    That makes little sense – the expansion started essentially at every point of the universe at once.

    “Energy frequencies”. Light is an energy frequency, …

    Err, no. Light is an electromagnetic wave, which has a frequency, and contains energy. Try learning what the words you use actually mean, please.

    “Every possibility should be considered” is a fundamental theme of science …

    Since there are essentially infinitely many possibilities, that’s simply impossible.

    I suggest a different prism to interpret what we detect…

    Well, then show that your suggestions are compatible with all the available data. Good luck.

    Does relativity apply in an expanding universe, but not necessarily so in an accelerating universe, or a contracting universe?

    There is no reason to think it doesn’t apply, and thousands of reasons to think it does apply. If you have an alternative explanation which fits all the evidence, then show your work, please. Simply saying “but it could be otherwise!!!” doesn’t convince anyone.

    Are you saying alternatives should never be considered?

    I’m only saying that armchair speculations with no supporting evidence should not be considered. If you have supporting evidence for your suggestions, show it.

    It would be a red shift for the light that has been traveling from afar and just now reaching us and we are moving in the same direction it is.

    Why should it? Also: what is “moving in the same direction” even supposed to mean? In what direction we move depends on the frame of reference one uses.

    The universe could even be pulsing (like a jellyfish) where some portions are contracting while other portions are expanding.

    Yes, it could – but the evidence says otherwise.

    Waves and particles both have frequencies of impact on whatever they meet.

    (1) What is “frequencies of impact” supposed to mean? (2) Particles don’t have frequencies.

    Energy frequencies is a useful term in that regard.

    No one here understands what you mean when you say “energy frequencies”, but nevertheless you insist that that term is “useful”…?

    We give serious consideration to a multi-universe, flapping branes and vibrating miniscule strings with countless dimensions, etc. I see nothing wrong with proposing what I have suggested for consideration rather than summary dismissal.

    There are big differences between the things in the first sentence and your suggestions: (1) they are compatible with the available evidence, and (2) they make testable predictions and are not mere armchair speculations.

    Attraction is present between things and its strength between any two things varies with distance.

    That attraction is commonly called “gravity”, you know…

    If the attraction strength variation of an orbiting sub-atomic particle is in the frequency range of light,…

    Pardon??? This is really gibberish. What on earth is this supposed to mean?! Again: could you please learn what the words you use actually mean?

  83. Valjean

    Bjoern. Happy living in the 20th century with its interpretations and conclusions that one day will be “What we used to think”.
    -30-

  84. Bjoern

    @Valjean: Nice non-response. Still no evidence for your assertions, still no sign that you try to actually understand the words you use.

  85. James

    82 Neil. I only raise the question because if something starts to expand there is an acceleration involved up to a point of max velocity then a slowing. The figures above seem to show the universe as expanding at a constant Where is the energy coming from to keep the universe expanding at a constant rate. If so, how long was the initial acceleration and when will the expansion slow down? If the speed of light is changing then our calculations would be flawed as the value of megaparsec (3.26 million light years) would be different?
    Or have I got the wrong end of the stick?

  86. Valjean

    Bjoern. I understand them. Obviously, you don’t, nor do you have any curiosity to try. Attraction is called gravity when between large objects…”force” when small, but large or small, it’s still attraction between two things, and it varies in strength with distance. Think outside current thought.

  87. Bjoern

    Attraction is called gravity when between large objects…”force” when small,

    Thanks for showing that you do _not_ understand the words you use. Attraction between objects with mass is _always_ called gravity, no matter how large or small they are!

  88. Valjean

    It’s strong force within an atom. But, call it what you want…it’s still attraction, large, small, weak, strong. Try thinking beyond the restrictions of current dogma. Many do.

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