Okay, I’ll admit, I am a novice when it comes to the sciences, like physics for example. But I did study physics in high school. It was based on Newton and Einstein, with maybe a little quantum physics thrown it. And time was featured prominently in it.
Now I learn somewhat more recently that some people reject the concept of time. I just know I saw a story on tv a couple of years back where an amateur British physicist had a theory that there was no such thing as time, in physics at least (obviously, I don’t have a link for this). And I read sometimes on these boards that some of you believe this as well (there are many examples of this, so I won’t provide a link for this either).
So I guess my question is What happens to the variable of time in all the equations I had to study back in high school? Some people, for example, believe time is the fourth dimension. If there is no time, what then is the fourth dimension? Furthermore, consider concepts like Einstein’s theory of time dilation. The faster you go, the slower time moves. If there is no time, then what is moving slower? And there are probably many more examples I’m sure.
Again, this is from a novice who has a very simple view of the subject. But I still think I bring up some good questions.
While I have seen a variety of different ways of dealing with time, some of them perhaps nonintuitive to a layman, I don’t think I’ve ever seen anyone proposing doing away with it altogether. Link?
I was afraid someone would ask for a link. Well, if you insist I could offer this one from my last thread. As you can see, if you scroll up a little, Jihi says:
(As you can see, we are talking about “Anti-time” from Star Trek: TNG to put this in its proper perspective.)
The only version I’ve seen is Julian Barbour’s book The End of Time. He suggests that all possible permutations of matter and energy in the universe exist in a simultaneous timeless status. Some of these permutations contain within them the illusion of time (for example, some possible arrangements of neurons in my brain might appear to be encoding memories of past events) but there is no causal connection between the past and the memory. We only make the connection because it’s a way of constructing a coherent world line that traces a path through the static moments.
Yes, I’ve never understood people who try to argue that time doesn’t exist. As in, at all. Seems a little rash to me. There have been a couple threads about it this year, on this board. If I have it right, the argument usually seems to be that in the same way the color red isn’t real — that is, while photons of that frequency range are certainly real, the sensation of redness is a fiction put on by your mind — time also is an illusion, a purely mental construct.
I don’t think practicing physicists embrace that view, and I think it’s hooey myself. (On preview I see Chronos is here for this. Good.) Even if time is something different than what we perceive, or is more complicated than what we perceive — maybe it needs to be modeled with a complex number or something —it still seems to be an obvious physical phenomenon of some kind.
Another idea I’ve read about is that the entire spacetime of the universe is already laid out, as one gigantic four (or higher) dimensional structure, and the moment of “now” is just one slice through that structure at a particular point on someone’s worldline. In this view, things are not moving through time. All of spacetime is static.
But in that case, time would still exist. It would just be an odd kind of spatial dimension, when you see the universe from the right kind of space.
This is the closest thing to what the OP describes that I’ve experienced, that also satisfies the criterion of some threshold number of physicists taking it seriously. Including myself.
In other words, what doesn’t exist here is the flow of time, as we normally perceive it. It is unclear at present how to resolve this notion with the fact that we do indeed perceive a flow, and the directionality implied by the second law of thermodynamics.
Even in this picture, time would definitely still be distinct from the spatial dimensions.
That’s actually not all that difficult. Our own perception (in particular, the fact that we have memory of the past) is itself a consequence of the Second Law. This becomes much more clear when you define entropy in the modern way, in terms of information theory.
And having seen some examples of what the OP is talking about, all I can say is that that’s not physics, that’s philosophy.
Sorry I don’t have a link, but I can report that a Physics professor at the University of North Texas (in 1998) spends half a lecture arguing to Physics 101 students that time doesn’t exist. I argued back during class that whatever his arguments amounted to, there’s still something that gives the impression to us that time is flowing, and whatever that something is, “that all men call ‘Time’.” Prof gave up after a while (mostly because I wouldn’t shut up–I don’t flatter myself that I “won” the argument) and a bunch of fundie students came up to me afterwards thanking and congratulating me, which was awkward.
Yes, you’re right. But there is still no answer to the question of why the second law alone gives time a direction, and furthermore how a statistical law such as that one produces a uniform arrow of time. This paper, Physics - A Quantum Arrow of Time , seems to have a theory, although I have not waded through the details enough yet to say whether or not I agree with it.
To the physicists: does General Relativity impose a stronger “arrow” on time than the Second Law of Thermodynamics?
After all, matter can fall into a black hole, but can never leave. That’s definite. On the other hand, a tepid cup of tea can always turn into a hot cup of tea with a floating ice cube. It’s astronomically unlikely to happen in any reasonable time frame, but not strictly forbidden.
To put it another way, if I showed you a film of a spaceship emerging and escaping from a black hole, you’d know the film is running backwards. (Or that it’s a total fabrication.) On the other hand, if I showed you a film of 20 air molecules bouncing around inside a connected pair of gas tanks, and at one point in the film all 20 molecules come together inside just one of the tanks, then all you could say is that this event is unlikely to happen within such-and-such a time scale.
Best book I’ve ever read on the topic of time: About Time by Paul Davies. It discusses the issue in the OP and many more, and is very easy to understand, even for someone who only had high-school physics.
Congratulations, you just discovered the problem Stephen Hawking (and many other physicists) have spent their careers on. It’s called the information paradox, and is still an open problem. In the 1970s, Hawking’s proof of black hole radiation and subsequent evaporation eliminated the previously accepted idea (information can fall in and never get out, but it’s not removed from our Universe, just stored where we can’t get at it). The leading approaches at present postulate various quantum fluctuation based effects that result in the information indeed continuing to be available to observers outside the black hole.
For example, one idea is that the informational essence of everything that falls in is (roughly speaking) smeared across the event horizon. This would take your “rocket ship exits black hole, film at 11” scenario and reduce it to the same thermodynamic analysis as the tepid cup of tea suddenly becoming piping hot.
So, the short short answer: no one is quite sure yet, but probably not.
Perhaps the OP is thinking about Julian Barbour, who is a British physicist not working within established academia, though no amateur either (he does have a PhD in physics). He doesn’t strictly argue for a timeless universe, but to him, our concept of time merely emerges from motion, the fundamental reality being a timeless trajectory through the space of possible configurations of matter in the universe. In this paper (PDF), which won last year’s FOXi essay contest, he outlines his theory in a rather accessible fashion.
According to an explanation I heard, everything is moving at the speed of light through space-time. The faster you go in space, the slower you go in time. Light, which travels at maximum velocity in space, doesn’t move in time.
I feel … a … bad joke … coming on… Can’t … resist…
Q:Why can you always hit a photon?
A: It can’t move in time. (sorry)
Need a better view?
Imagine a continuous (horizontal) sine wave. Now cover what you can see with a piece of paper, but cut a one wavelength square out of the middle of the paper. Now, as you move the paper left or right, the wave you’re looking at appears to oscillate, but the sine wave itself is static. Imagine a point at the front end of our “light wave.” From the time the wave begins occupying this point, until the wave passes and ceases to occupy this point, it is static. Like someone else said, x=x[sub]0[/sub]
I’m one of those people who believe that time “doesn’t exist”. I speak only for myself, not anyone else. I’ve tried to understand some of the evidence that time exists (most notably the time dilation stuff) but I just don’t get it to the point where I can really believe in time.
I’m just trying to answer the OP’s questions from the point of view asked for. The following is not presented as fact in any way, just explaining the point of view.
I know most of this is pretty much laughable to actual physicists with a PhD.
Nothing. “Time doesn’t exist” is really just saying there is no physical manifestation of time. So things like time travel (going to arbitrary points in the past/future) aren’t possible for that reason. Things move, and time is the concept we came up with to describe that motion. Once something moves, it’s no longer where it was, and that’s that. Basically, I reject the concept of space-time. Yes, I realize there’s a lot of people smarter than me who don’t. I say there’s only space.
For me, they’re not the same thing. I think a 4th dimension is possible and might exist. If it does exist, it’s not time.
For me the problem is that you can’t test time dilation without using a physical clock of some kind. The change in motion means different forces acting on the clock, which makes it behave differently. It doesn’t prove time exists, it just proves that motion has an effect on the properties of the clock.
I know it sounds crazy, but if time dilation didn’t happen, that to me would prove the existence of time.
So yeah, that’s my crazy interpretation of the world around me. I realize the madness of calling myself crazy 3 times yet continuing to persist in my interpretation.
I hope this was at least enlightening or amusing in some way.
