Past, Present and Future

[--Pete]

Hi,

I'm sorry, but there are a few errors and misconceptions in your post. The fundamental question in this thread is not 'what is the future' but rather 'is the future fixed'.

To be short, there is no answer that any of our brains can completely comprehend unless one of you is Hawking in disguise.

Without knowing what the answer is, it's a bit premature to assume we will not understand it. Or that Hawking will.

The future is a relative concept.

No, it is a well defined concept. For any event, all the space-time contained in the light cone of that event is either its past or its future. To determine which of the two, one uses the second law of thermodynamics. The direction in which the entropy of a closed system increases is the future.

It is we who perceive time (spacetime in this case) as passing, but it is merely another dimensional axis. To us, there is a future because we move along this axis.

Meaningless. That's like saying, "when you take a trip, you perceive the scenery passing, but it is merely another dimensional axis." True, but vacuous.

So to us, there is a present, while for an imaginary observing living outside these dimensional constraints all moments happen at once.

This is total nonsense. You can postulate anything you want. An imaginary observer for whom everything happens at the same place. One for whom the universe is a single event and all space and time is collapsed to a point. An observer who lives in a six dimensional universe, where there are multiple time axis (RAH The Number of the Beast). Or even one where children never grow old and can fly with the help of pixie dust. It's called 'fantasy', and if done well can be great fun. But it is not a good basis for modeling the universe.

But let me borrow a picture from Wikipedia that makes this a bit clearer I hope:

http://upload.wikimedia.org/wikipedia/comm.../World_line.svg

.svg? Sorry, but a link to something that requires me to find and download some program to view it is just a bit too much trouble.
EDIT: I think I found your picture.

Shown here is space (all 3 dimensions, but represented in a 2d surface so our limited perception can understand time added to the picture as a 4th dimension. Here a single proton (light 'particle') travels. In the future or past it may be in different locations, depending on events that modify it's course.

Of course, without actually seeing the image you are referring to, I don't know if the errors are yours or its. However, at the very least: a 'proton' is not a light particle, a 'photon' is. And a photon is *always* moving in any reference frame other than its own, and it is moving at the speed of light in all those frames. Of course, if you want to get even more 'correct' the photon isn't really moving anywhere. As the single photon interferometer experiment displays, the trajectory of a photon is a meaningless concept. But mixing relativity with quantum mechanics is a bit tricky.

Now, if you followed me so far: congratulations, you made an important step on your road to understanding quantum mechanics.

Actually, someone who has made it uncritically to here is more misinformed then when he started. Most of what you've said is, quite frankly, BS. And nothing of which you've addressed has anything to do with quantum mechanics -- it all falls under the domain of relativity. The two theories are not only separate, but to this time, irreconcilable. Really, if you're going to honestly discuss these matters, perhaps you should at least take the trouble to know the name of the field you are discussing.

I can't explain it as well as Hawking can (I TRIED understanding his book, but after 8 or 9 dimensions my brain hurt).

Which book? He has written several. Some are for the general public, at least one for is people who actually understand the subject (The Large Scale Structure of Spacetime, I linked to it in a previous post). If it is this last one, then congratulations if you understood any of it. It takes a certain natural talent for math along with years of study and practice to be able to think at that level on that subject.

Ok, now it gets interesting. Is the future as defined as the past? We perceive past time as a done fact. Is the future a done fact as well? Yes, it is for people who are in the future, who perceive our present as past, some might argue.

?

The counterargument is that time travel is impossible. That time is immutable and people can not move to future or past.

Whether time travel is possible and whether time travel can be used to change the past are actually two different issues. And they are tangential to the question of whether the future is fixed.

Then there's the theory that there are infinite dimensions, one for each 'possible' timeline. A particle took a left turn or a right turn when it hit another perfectly. Each option spawns a dimension.

This, of course, makes the original question moot. Since every possible future will occur, asking if 'the' future is fixed is meaningless. The best one could say is along the lines of "collectively, they're fixed, individually, they're not."

But it has already been proven that within our universe it is possible to modify the effects of time. At super heavy singularities (black holes being the most popular example) the effect of time is altered even to our limited perception. For all intents and purposes, time does either not exist or is held immobile in a black hole from our perspective, while it may very well exist from inside the black's hole perspective.

You don't need anything nearly as exotic as a black hole. Velocity and gravitational time dilation combined-effect tests using nothing more than precision clocks and airliners have done a sufficiently good job of supporting relativity. And millions verify it daily when they use GPS.

BTW, 'super heavy singularities' is redundant. A singularity is a point in space-time where the curvature becomes infinite. Although it has been speculated that a naked singularity might exist under some circumstances, singularities are still strictly a theoretical concept. Most 'regular' singularities, if they exist, are shielded by an 'event horizon'. By their very nature, they are regions where the theory fails. Perhaps you meant 'super heavy black holes'?

Scientists are still trying to figure out what the future is theoretically. Is it malleable or not? Are we just simply acting out or lives, while the outside observer already knows everything that will transpire to us? Or are we changing it as we go, and if we do, do we leave behind an infinite amount of mirror universes for every particle that collided and chose left or right?

Right now, these are questions in philosophy, not science. There are, AFAIK, no proposed testable theories to explain or predict any of those speculations.

First what we have to do is define time. No one defined what time really is yet.

Been there, done that. See above. It's as well or as poorly defined as 'space'. One defines things by their properties, and the properties of space-time are pretty well understood on the level we've been able to observe so far. We might, probably will, have to refine those definitions as we learn more. But the new definitions will have to reduce to the present definitions in the domain of the present definitions.

The damn thing is that we're trapped in time and lack the outsider's perspective who can look at time without being affected by it. We can see time doing strange things when near singularities. to our perspective it seems to slow, but in reality it's not time that's changing, but merely our perception of it. This is part of the theory of relativity and theories derived therefrom.

No. Were trapped in space, too, and yet nobody seems to think we can't understand it. And, to each observer anywhere, one second takes one second to pass in his reference frame. Our perception of time remains the Newtonian flow at a constant rate. It is only when we compare our observations with those in a different frame that we find differences. But the observers in each of the frames do not perceive these differences.

Quantum mechanics tells us something different altogether, but it's so damn complex I can hardly comprehend it.

That's because you don't know its language. No natural language contains the concepts and the means to manipulate them that quantum mechanics requires. Learning the prerequisite math is difficult. 'Understanding' quantum mechanics once the math has been mastered is not. I put 'understanding' in quotes because it is not the type of understanding we normally think of. We understand how a saw cuts wood. We have a mental image of the processes, of edges and hardness and sharpness. In quantum mechanics, we have nothing but the math. We can develop an intuition for how things work, but it is a different type of understanding.

For starters, you have to ditch every concept of the universe as we know it, because those laws for the most part don't apply to the subatomic soup where quantum mechanics plays out.

Yes and no. One of the basic axioms of quantum mechanics is that it has to reduce to the classical limit when appropriate. Thus, a baseball has a trajectory in quantum mechanics, and it is the same as that of classical mechanics. Just a bit more difficult to calculate.;)

For example, an electron circling a proton can be at any point in a certain orbit. But it can't be predicted by the outside observer. It's impossible to tell where it will be in any moment in time, according to quantum mechanics it's in all places at once and none of those places at the same time.

Actually, 'circling' and 'orbit' are meaningless in this context. QM does not even address the question of the location of the electron, indeed in this context, location isn't even a concept. It is possible to tell (i.e., measure) the location of the electron, but that disrupts the system so that it is impossible to predict where the electron will be. QM does not say "it's in all places at once and none of those places at the same time". Indeed, all it tells are the odds of finding it somewhere. The plots of the probability distribution are often (mistakenly) presented as location maps of the electrons. Indeed, even their name, atomic orbital, is a throw back to the old quantum theory.

Now, your brain is protesting right now, I know. It's shouting at your it MUST be at one place. But that's the tricky part, this is not true in the quantum mechanical level. Here's a video explaining it:
http://www.dumpert.nl/mediabase/887801/a71...mmechanica.html

Nice video, suitable for elementary school science class. However, if you pay attention to it, you'll notice that nothing is explained. The behavior of the two slit experiment is presented, the results under different conditions are also presented (and, BTW, the results shown for the single slit is incorrect), but there isn't a word of 'explanation'. Instead, there is a bunch of anthropomorphism, with things like the electron choosing and 'as if it knew it was being watched'. Trying to understand QM in this way is a little like mapping the audible spectrum into the visible spectrum, using the map to translate music into colors, and then using the result to understand the Fifth by looking at its picture. At best, the understanding will be superficial and inherently wrong.

So even in our own universe, there are different possibilities happening at the same time. Weirdness. And you want to tell what time is? Good luck.:)

Actually, there is no such thing as the same time without also having the same place. Otherwise, it is relative.

Please don't take this as an attack on you. I am simply trying to set the facts right. If you were spreading misinformation about a game related topic, many would object. And yet, it would only be a game. To me, at least, reality is more important than a game.

--Pete