@Alan (38.) Having first-hand NDE experience I’ll explain something in short that probably nobody has. Your body floats up… no. We know that the subconscious does tons of work 24/7 in the background. Processing information, accessing memories, imagining what’s out of view, and so on. When the experience occurs synapses misfire due to lack of oxygen, blood flow or whatever, and you’re practically wired into it on a conscious level. It’s overwhelming. You can’t tell what’s a memory, real or a dream. “Vivid dreaming” comes to mind but a jumble of many at the same time even after you wake up. People halucinate (see/hear) ghosts from their past talking to them, spirits, the operating room, heaven, all kinds of stories. Keep in mind that all accounts are after the fact and the effects can take days, weeks, months to fade if ever and the stories are after the fact. So basically all the stories can be explained as situations constructed from what already existed before including memories and beliefs, and a powerful subconcious. Most just aren’t prepared for this mental state which can be quite scary if they don’t understand it.

I just would like a reply to my very simple questions.

Great references, thanks! I think I may have read The End of Eternity once, but if so it was so long ago that I recall nothing at all about it. In a different series I do like the scene of Marvin pacing on that moon literally until the end of eternity in the HHGTTG series, when his time-traveling friends finally bother to pick him up. Somehow it feels like I’ve had friends like that… or maybe it’s just that I’ve been a friend like that? Like the time my brother called me after arriving at the airport, while I was a hundred miles away picking up my son? A bit of time travel would have come in sooo handy that time…

That people of science are not humble is among the most laughable of misconceptions. They are indeed the most humble simply by virtue of the fact that they – like no other group of human beings – agree that pictures about the way the universe is must be grounded in the most stringent experimental constraints and logical consistency. It is these constraints then, and not the feeble mechanisms of the mind, that legitimize the method and reflect the humility of its practicioners. Our planet is still a haven for explanations about our origins involving six days, and postmortem scenarios invoking flush gardens soaked in optical light. Scientists are hard to come by. Please go bother someone else.

I recommend of course The End of Eternity by Asimov, which is actually a spoof of time-travel stories in that it uses all the cliches and really goes over the top—but ends up being one of the best time-travel stories of all time. (In this respect, it is similar to Jethro Tull’s truly excellent Thick as a Brick which is a spoof on 1970s concept albums but actually turns out to be better, by their own criteria, than the things it spoofs.)

There is a very interesting book which reviews time travel in science fiction and in science by someone who knows about both: http://books.google.com/books/about/Time_machines.html?id=39KQY1FnSfkC Recommended almost as highly as Zen… and …Brick.

In the 1995 a sort-of science fiction novel by Stephen King was made into a movie called The Langoliers. As you would expect for a Stephen King book, the set up was primarily a horror-drama with the usual selection of ornery and outright demented people, as one of King’s scary-smart young girls with telepathic powers that he seems to favor for many of his stories.

Now what was interesting about this purely-for-entertainment work was that King put some non-trivial effort into developing a theory of the flow of time, one in which he then places his characters to stress them out and make them do the sorts of things you expect in Stephen King novels. In a nutshell, King’s theory of time goes roughly like this: The “now” in which the universe exists moves not through some abstract definition of time, but through a quite literal empty space in which “now” is more like a spaceship in motion than a system in evolution. Change takes place within the spaceship, but in a way that is independent to some degree of motion through the literally space-like time dimension.

That’s sort of interesting, but what really captured my attention about King’s model of time flow was that he placed incomplete versions of the universe both in front of and behind the moving location that defined what “now” is. King’s leading-edge incomplete universe was bright, fresh, and full of the promise of change, while his lagging universe was stale, fading, and clearly head towards a bad end. This being a Stephen King movie, he of course placed the crew of an airplane first in the lagging universe, where they would await… what?

The Langoliers, of course. The Langoliers might best be described as the ideal nightmares of someone who is frightened horribly by large drill bits and empty spaces. Their purpose? Recycling of course! The Langoliers are the überscary (well, by 1990s CGI standards they were) chompers and eaters of the past, leaving it in place only long enough to (I guess) reinforce the real “now” further up the chain. Once the Langoliers recycle the ragged trailing edge of reality, however, it is gone forever — all that is left is a gaping, empty vacuum from which “now” is hurrying away at breakneck speed.

And therein lies what I like most about Stephen King’s version of the flow of time: He simply creates an intuitive model that deviates in the most fascinating and heretical ways from “standard” spacetime physics. Why shouldn’t he? His only purpose was entertainment.

Yet it’s a fascinating model about which to ask some of the same questions that perplex far more learned models of the flow of time. For example, can you travel in the past in King’s version of spacetime? Yes and no, since you can go a short ways back, but no further, and even that distance is ragged and unpredictable. Can you visit the dinosaurs? Definitely not, since they only exist as memories stored within the Present. The past in King’s universe is nothing more than the lonely and empty road left after the first, last, and only bus there will ever be passes over it. Only the memory of dinosaurs lives on in the images and information within the bus of now, just as the bones we find in our actual universe are nothing more than memories of a past that is no longer accessible as a existing place.

In King’s universe, can you change the present by altering the brief past that lags behind it? No, because that past is only a subset whose impact on the present fades quickly as you move farther away from now. Can space be curved? Well, yes, but probably only in the sense that the bus that represents all of now can be curved or bent, since only that part contains space as we would perceive and measure it with instruments. Are there infinite worlds? No. Are there infinitely long world lines, what is often called the “block” (as in “solid like a block from start to finish”) universe? No, only short dangling world lines that extend a ways into both the future and the past. Can the waves of quantum mechanics grow without limit? No, because there is no room for them to grow; they are captured and must resonate within the bound of the Bus of Now.

If Now can be bent, might the wormhole solutions of general relativity allow travel back in time within King’s flow of time? Probably… but you would only find empty space when you got there, since time in King’s universe is an infinite sequence of empty spaces through which the occupying mass of Now moves. Can Sean Carroll’s vision of complementary universes moving in opposite direction in time be accommodated? Sure, but in an almost trivial way: Both universes change in the same way, they just literally travel in opposite directions down the long road of empty spaces. In King’s universe time is not so much space like as it is two separate variables, one for distance along the path of empty spaces (t), and another, call it tau (that’s not standard incidentally) for “change like a clock hand moving.” That kind of choice is a programming or data representation issue, and so is not necessarily fundamental to physics if precise equivalence is maintained. Cramming multiple meanings into a single variable is what computer types call overloading. It can be a handy technique for expressing issues compactly, but some willingness to recognize provably equivalent alternatives can also be helpful for finding cleaner or more understandable ways of representing ideas.

Now here’s a more hypothetical question that I don’t think King had in mind, but I don’t want to be too quick to judge him on that either: Is there a plausible physical interpretation for why a universe would have leading and lagging edges to it, that is, partial versions of itself that cannot exist or change in isolation, but which somehow assist the main Now of the universe to function and work?

This more than anything else struck me about King’s flow of time, because I think you can make a surprisingly deep argument that whatever the universe is, it does indeed require roots that extend into both the past and the future. The reason is that at a profound level, much of physics seems to operate on a principle sometimes called minimization of action, action being an odd product that has the same units as Planck’s constant. One way to get a tiny bit of a graphical feel for how this minimization of action works is to imagine particles as rubber bands that are stretched between points in the distant past and other points in the distant future. Near the middle of these bands is the Present, where forces and potential energies cause the rubber bands to stretch and move sideways in interesting ways. The tension of the rubber bands can then cause them to interact and interplay with each other can, producing in many cases results that seem strangely prescient, almost as if the particles could see in limited ways into the future — which of course with those rubber bands extending into both the future and the past is sort of what happens.

I should mention that this whole peculiar issue of particles being smarter than they have any real right to be, at least when it comes to responding to energy potentials, is one of the reasons why some physicists like to extend those rubber bands all the way from the start of the universe to the end. At that point they become what are called world lines, and the resulting universe of infinitely long rubber bands becomes the “predetermined” block universe I mentioned earlier.

King inadvertently (?) proposes a scheme that is far more appealing to computer folks, which is to make the worldlines virtual. That is, to help the Present respond meaningfully to its array of diverse forces and potentials, King’s worldlines appear to extend as far as they need to into both the future and the past… but no farther. Once their action minimization duties are completed, the rubber bands in effect snap back towards the fabric of Now and become available for building new virtual world lines to explore new possibilities and potentials.

And that gives another answer to a question someone might want to ask about King’s flow of time:
Why is quantum computing so hard? Well, in King’s universe that’s easy to answer: The worlds being used to calculate more powerfully are virtual only, so they can only exist for as long as the lagging edges of the recent past can be coaxed into hanging around. Eventually, inevitably, and without exception, they will snap back into the fabric of Now upon which their existence depends. And when that happens, any quantum computing will be over. The overall result in King’s universe is that quantum computing becomes a matter of balancing cantankerous noodles on their ends. It can be done, for a while, but in the end it will always collapse back into the ordinary physics of Now.

And last but not least, there’s an ugly beast — the Langolier. What would it be in such a universe? Would a real-physics analog to the destruction of packets of virtual worldlines a thing of beauty, or would it be as ugly, scary, nasty, and poorly understood as King’s Langoliers?

I vote for ugly, because the beast already has a name in real physics, and it’s not much liked in many circles: wave collapse. That is, to make virtual worldlines real and a part of actual physics, you unavoidably must also make their destructors just as real. Many physicists do not like even the idea of operators of this type, which have never been well quantified and which have annoying properties such as changing or collapsing entire regions of spacetime. One answer to that is to avoid such operators. Another is to get creative and look for some entirely new ways to do math.

And the end: Why have I bothered with all of this?

Because I just wanted to point out that in physics, interesting and even entertaining ideas can lead to conclusions that are no more absurd than wondering if the ability to think and remember might require the redefinition of all of physics.[1] Three cheers then for Stephen King, who took the time to explore some wild ideas for how time works for the purpose of entertaining, yet surprisingly wound up with a collection of ideas that both resonate and conflict with modern physics thinking in a number of truly fascinating ways.

———-
[1] I know nothing of all that argument, but I would make this observation again: If Now is just a set of memories, as in the King universe I just described above, then any measurement of a time difference unavoidably depends in part on memory and intelligence. Why? Because the past cannot be observed directly, even if you believe it still exists. Thus you can at best only measure time as it exists between the real instruments looking at Now, and the intelligent memory constructs that we call Then. Forget about observers being needed in quantum mechanics: Every invocation of time or t in classical physics calls for an intelligent observer, and does so just as forcefully as do the precepts of quantum mechanics.

Sounds like bad poetry written by a bored 15 year old after flipping through A Brief History of Time.

I’m presently working on a more rigorous version to submit to a respectable journal. I believe that the Concordance Model has some definite fatal flaws that can be amended by a new model without a wholesale revision of our fundamental laws. I will need a little luck, a lot more hard work, and some ironclad proofs, if I want to have any effect on the status quo.

Whether nature or intelligence can fiddle with the spacetime curvature enough to allow this is of course still unknown. Does anyone have a massive near-infinite cylinder rotating at relativistic velocities handy?

“Sean, I wonder what the implications of this on discussions of free will/decision making are? If the four-dimensional universe includes our world line are we simply deterministic machines with our consciousnesses providing an “illusion” of the ability to make decision when from the full-dimensional view it is simply following its worldline?”

Our ability to make decisions and the decisions themselves are just as real as anything else in the block universe, not illusory. But of course the decisions are all there in spacetime, it’s just we experience them serially.

We wouldn’t gain anything in terms of control were we somehow able to extricate ourselves from our worldlines, since exerting control is a particular sort of pattern in the worldline itself, namely when getting what we want follows from what we do, http://www.naturalism.org/spacetime.htm#inevitability

As someone with a long-term fascination about methods and heuristics for determining when complex information is worth analyzing closely, and conversely when it should be discarded quickly, that paper reminded me of simple point: If an argument is based on a huge number of ideas that individually sound impressive, but which on average have never been well verified, the real chances of the argument being valid are… well… vanishingly close to zero. (This is also a simple way of explaining why I am am incapable of being impressed with the enormous work and detailed reasoning that has gone into string theory over the past several decades.)

So, if I may add a qualifier to my last question: Sean Carroll, would you happen to have any simple, well-focused, and perhaps even experimentally meaningful approaches to reconciling your idea of a real “now” with the idea of a block universe? My emphasis here is on “simple.” If an issue this fundamental to how existence operates cannot be explained by using only a very small number of conceptual building blocks, it’s time to go back to the whiteboard and start over again.

A direct question to Sean Carroll if you are still reading this thread:

Both special relativity and quantum theory include strongly deterministic threads, e.g., the reciprocity of “now” in SR frames and the advanced EM wave solutions of Feynman’s thesis.

If you have a moment, would you share your views on how to reconcile the idea of a real, non-trivial “now” with those parts of physics that seem to imply predetermined worldlines?

Of course your questions are great. How about an extended mind? There was a conference in 2009 to do with this. Can this explain somehow? If people are seeing during NDEs can optics get bypassed? There are very good cases. Is there a subtle body doing the seeing?

Lloyd Rudy (from above) – “he was up there!”

http://www.rcpsych.ac.uk/pdf/SIG%20Website%20April%203rd%2009%20Programme.pdf

Answers on one sheet of A4 only please.