The Theory of Time

[Mystery111]

It's a bit short, maybe more detail could have gone in, but I said to Appolinaria that I would write a thread up on time. Since the recent interest in it, I thought best do it now.

 

The Theory of Time

 

 

Quantum physics brought a new understanding, a new picture if you like of time and the way we previously understood time seemed to prove innacurate. The theory seemed to predict that there was actually no flow to time [1][2], a strange new understanding in current theoretical physics as we seem to have the experience that there is some kind of linear flow to time. General Relativity also generates motion that is a symmetry of the theory it is not a true time evolution. Diffeomorphism constraints on the theory return a vanishing time derivative which gives rise to the existence of the General Relativistic Wheeler-deWitt Equation. This equation has a wave function which describes the entire universe. In this equation there is no real time evolution. This leads to a new concept of timelessness; a universe where there is no dynamical change as a whole.

 

This leads to yet another paradox since inside the universe, us, as intelligent recording devices seem to have an experience of objects dynamically changing from one moment to another.

 

It seems that our psychology may play the largest part of all when concerning why time seems to flow into the future from our past; in fact Newton said it best, "absolute, true, and mathematical time" which "in and of itself and of its own nature, without reference to anything external, flows uniformly and by another name is called duration" with what he defined as "relative, apparent and common time".

 

It seems to have the ability to sense time pass, where events are changing requires the ability to discern a past and future where you are stuck in a present frame of time. To have the ability to sense a flow, the brain must take a series of events and mold them into our psychological understanding. For us to have this linearity, we take the past as an objective fact of experience: The future is evident to us as a history we are yet to explore. This happens, we presume, when one passing moment suceeds to another in total symmetry with the idea that somehow space is linear.

 

 

Well, one hard thing for the mind to comprehend is the fourth dimension of space. It is an imaginary leg off the real spacetime triangle and this leg is part of the ordinary geometry of the universe; this leg is the imaginary space dimension of time. The geometry of ordinary space has time as part of this structure. This should not be ignored, but it should also be noted that the idea might be flawed. It is true time in every respect of the sense, seems an invariant of space. But space is not divided into a past and a future where there is the present frame according to physics. In fact, the most famous account of this was spoken by Einstein:

 

''For those of us who believe in physics... The past, present and future are only illusions, even if stubborn ones."

 

This would mean that there must be something drastically wrong with our classical way of thinking about time; the way Newton himself defined as. If there is no such thing as a past and a future, it would mean on the drastic scale of things, that there only ever existed the present time. The boundary between past and future are explicitely part of our make-up... so there would be a gene responsible right?

 

Right. It's called the Suprachiasmatic Nucleus. A gene which regulates the perception of time; it is the reason why we may feel one event seem longer in a short time, than one in a short time but feels longer. Actually, the human body has atleast seven internal clocks which regulate certain cycles such as eating, drinking and sleeping.

 

So it seems that ultimately, time seems to exist (to us) because of our biology and our psychological make-up. It certainly places a lot of questions on whether time is actually an objective feature of the world. Another question that might be raised, is whether timeless models such as the Wheeler deWitt equation describe real time evolution. In Prof. Hawking's model, the universe can be modelled under an imaginary time. In this model, you simply shift the way you view evolution. Turning your equations time parameter [math]60^o[/math] you are able to view the universe as though it has no boundaries and thus eliminated the idea that our universe had a beginning.

 

 

Hawking stresses however that the big bang still happened, it's just a new way to view the universe under a different time description. The events we actually experience are real time events. The moments we observe in present time are made in real time evolution with reality appearing as the square of the wave function.

 

So it must be said that objective time may not exist, but indeed time may not even exist at all according to one interpretation of General Relativity. Of course, there is quantum mechanics description of time as well, which we never covered. In this interpretation of time, time is a series of starts and stops, just a sucession of momentary fleeting flashes of existence. The brain however, somehow binds this reality together. This binding process allows us to associate past events from the present and future from present.

 

Whatever the true description of time, we should atleast trust our current theories unless something new progresses which may cast doubt on it.

 

 

 

[1] - http://www.fqxi.org/data/essay-contest-files/Ellis_Fqxi_essay_contest__E.pdf

 

[2] - http://www.motionmountain.net/download.html

 

"Time is a concept introduced specially to describe the flow of events around us; it does not itself flow, it describes flow. Time does not advance. Time is neither linear nor cyclic. The idea that time flows is as hindering to understanding nature as is the idea that mirrors Page 71 exchange right and left. The misleading use of the expression ‘flow of time’, propagated first by some flawed Ref. 36 Greek thinkers and then again by Newton, continues. Aristotle (384/3–322 bce), careful to think logically, pointed out its misconception, and many did so after him. Nevertheless, expressions such as ‘time reversal’, the ‘irreversibility of time’, and the much-abused ‘time’s arrow’ are still common. Just read a popular science magazine chosen at random.''

[michel123456]

From your link

 

6: Conclusion

The view proposed here is that spacetime is extending to the future as events develop along each

world line in a way determined by the complex of causal interactions; these shape the future,

including the very structure of spacetime itself, in a locally determined (pointwise) way. Spacetime is

an Evolving Block Universe that continues evolving along every world line until it reaches its final

state as an unchanging Final Block Universe. One might say that then time has changed into eternity.

The future is uncertain and indeterminate until local determinations of what occurs have taken place

at the space-time event `here and now’, designating the present on a world line at a specific instant;

thereafter this event is in the past, having become fixed and immutable, with a new event on the world

line designating the present.

 

Emphasis mine.

I disagree strongly with this point of vue.

As i stated in another thread on this forum, if one accepts that we are moving through time, then moving means moving, not remaining in place and duplicating at another spacetime coordinate.

[Mystery111]

From your link

 

 

 

Emphasis mine.

I disagree strongly with this point of vue.

As i stated in another thread on this forum, if one accepts that we are moving through time, then moving means moving, not remaining in place and duplicating at another spacetime coordinate.

 

 

I agree with you. The references are only used to refer to the subject at that moment. Is this the physics textbook here we are referring to? The only qoute of importance is the part which says that no such thing as a times arrow exists. Anyway, I totally agree. Time does not move or flow.

[owl]

Mystery111,

As per your suggestion in the "present time" thread (Physics section), I bring my questions to you here, as follows:

From my post 89, “the present time" thread: Quoting Mystery111, post 71:

An eternal present simply means, the present time is all that is ever in existence.

This sums up the subject very succinctly. (I am bolding the present tense.)

But later, in post 75, you said:

Whilst the past is not happening right now, the past does have a now that is happening.

 

How can the past (no longer present) “have a now that is happening?” As per the “block universe” theory based on eternalism, in which the past and future are all somehow still present? (see below.)

Quoting the Stanford Encyclopedia of Philosophy: from my post 317 in Ontology of Time;

 

Presentism is the view that only present objects exist. More precisely, it is the view that, necessarily, it is always true that only present objects exist.

 

One version of Non-presentism is Eternalism, which says that objects from both the past and the future exist just as much as present objects. According to Eternalism, non-present objects like Socrates and future Martian outposts exist right now, even though they are not currently present....

 

I asked, “So in what sense if not total nonsense is the above statement true... existing right now but not currently present?”

What do you think?

 

In the same post, I quoted Wikipedia on eternalism:

It is sometimes referred to as the "block time" or "block universe" theory due to its description of space-time as an unchanging four-dimensional "block",[2] as opposed to the view of the world as a three-dimensional space modulated by the passage of time*.

I commented:

Count me among the opposition. The above denies presentism, that the future is not yet here and real and that the past is not still here and real.

 

You seem to agree. Right?

*Ps: I agree that the phrase, "the flow of time" is misleading in that it reifies time as an entity, like a river. But I have no problem with the phrase, "the passage of time" as the simple concept of elapsed time as things move, including clocks 'ticking.'

Edited November 9, 2011 by owl

[Mystery111]

''How can the past (no longer present) "have a now that is happening?" As per the "block universe" theory based on eternalism, in which the past and future are all somehow still present? (see below.)

Quoting the Stanford Encyclopedia of Philosophy: from my post 317 in Ontology of Time;

 

Quote

 

Presentism is the view that only present objects exist. More precisely, it is the view that, necessarily, it is always true that only present objects exist.

 

One version of Non-presentism is Eternalism, which says that objects from both the past and the future exist just as much as present objects. According to Eternalism, non-present objects like Socrates and future Martian outposts exist right now, even though they are not currently present....''

 

Block Universe would imply simultaneous past and future present states. There maybe a number of reasons why this might be a good model... but for me, it just doesn't work.

 

Let's be clear. I think we both agree that nothing ever exists other than in the present moment. There is nothing in theory, and it is from here we 'might' differ... is that in theory there is nothing which stopped us from believe that one present moment can be replaced by another present moment. That almost certainly places a limit on simply believing all present moments are happening simultaneously. You can have a present moment in the past which is happening by definition ''because it is a present moment'' but we have the special ability to discern this ''present moment, here and now'' from any other present moment which may be in our past and in our future.

 

Technically-speaking, our present moment, in fact no present moment is really special. You could have an infinite bundle of these present moments and in no way distinguish which present moment most accurately fits the current picture - instead to be able to do this, you must be able to discern the current present sphere we are in from any other. It is a contradiction to say more than one present moment can exist, especially when ''we'' are involved. That kind of behaviour mirrors the wave function. Let me explain:

 

You can have actually many different pasts. Let us equally say this ''sum over histories'' is in fact a ''sum over present histories''. This only happened because no one is around to view the present system and break it out of it's superpositioning. (In fact you can make a measurement in the present and effect the past, but that is a more complicated scenario). Focusing on the sum over histories example, we as recording devices acting as observers don't see this quantum weirdness on our levels. If we could, and we simply stopped to view this system, all the histories would deflate and what would be yielded is the most probable history. You can have many present moments, so it seems acting simultaneously but, it seems you cannot have it always that way. Having a past and future happening simultaneously doesn't seem to work very well, or it causes a lot of confusion and raises a great many questions. One might argue, creates more problems than what it solves.

 

''How can the past (which is no longer present) have a now that is happening?''

 

Odd isn't it I have said that the past and future do not happen simultaneously but yet, above this statement seems to contradict it.

 

It is odd, but there are ways round it. Suppose I wanted you at face value to just accept that no present moment in the past or future happen simultaneously. Ok.

 

However, I also want you to believe every part of our past had a present moment, or even has a present moment. I don't want to talk to much in the past tense; dynamically you are able to effect the past even from the future. I gave an example of this above, but never named it. It is called the Wheelers Delayed Choice Experiment. According to this experiment, effecting the wave function of a particle now in the present moment of time can effect the original state of that system in the past. For that to happen, there must be ''information'' being carried in the wave function back to the source where our particle was emitted.

 

Imagine a photon being emitted from a star in the past, lets say 7 billion years ago, and direction is irrelevent. All we need to know is that this particle has travelled the galaxy taking every route possible; this is our old friend, the Sum Over Histories, or as I called it, a Sum over all Present Times. The photon reaches Earth and hits a scientists detector screen and something remarkable happens. All those possible histories suddenly deflate to a single value, a single existence and a single history.

 

So is there a way physics can say, keeping in line that the past is still the past but isn't, if you know what I mean? Instead of us being lazy and saying all present moments are happening simultaneously, it can still be safe to say that the past and future have present moments, and are happening, they just aren't happening simultaneously. This must be true, afterall, if you can effect the wave function of something and make it's past state more real, then the past state must be happpening.

 

This is a matter of choice. For instance, I raise a question. If all present states are happening right now, what is stopping anyone from saying that all present states happen all time? Sure, you cannot reverse the entropy of a system once the egg has fallen and cracked on the floor. So the only way to say time is simultaneous in regards to all present moments is also to say that every present moment is happening now alongside our own present moment, and continues to do so as we move from one frame of time to another.

 

Or you can believe my picture. Present time exists for the past, but is not happening simultaneously with our own. The past is happening for it's own present time, but for our present frame it is not.

 

 

 

 

''

It is sometimes referred to as the "block time" or "block universe" theory due to its description of space-time as an unchanging four-dimensional "block",[2] as opposed to the view of the world as a three-dimensional space modulated by the passage of time*.

I commented:

Count me among the opposition. The above denies presentism, that the future is not yet here and real and that the past is not still here and real.

 

You seem to agree. Right?''

 

Partially. Again, the past is happening, it has it's own ''now''. It does not act simultaneous however to the future present state. I think theory allows one present moment to be suceeded by another. The past-tense moment is still a present moment however. It is just not currently THE present moment in respect to our observations.

 

To give you some taste of Absorber Theory in the Transactional Interpretation Method of treating the wave function as time-symmetric function you have one quantum wave moving forward in time, classically names ''an offer wave'' and a wave moving back in time ''echo wave.'' This is an advanced and retarded wave solution of the form

 

F1~e^[i(kr - ωt]

 

G1~e^[-i(kr - ωt]

 

The idea is that the the absorbing electron responding to the incident of the retarded field F1 in such a way it will gain energy, recoil, and produce a new retarded field F2=-F1 which exactly cancels the incident field F1. The net field after such a transaction is zero.

 

F(net) = (F1 + F2) = 0

 

 

 

 

The Transactional Intepretation is the only interpretation of the Wheeler delayed choice experiment which makes most sense.

 

 

 

Edited November 10, 2011 by Mystery111

[owl]

Mystery111,

I think you are confused at a very basic level about "tense" as in "was, IS, and will be."

This is abundantly clear in your statement (my bold):

Again, the past is happening, it has it's own ''now''.

The past has happened. The future will happen.The present is happening.

Yet you say:

Let's be clear. I think we both agree that nothing ever exists other than in the present moment.

Yes. "Exists" IS present tense.

But then you go into such apparent nonsense as,

one present moment can be replaced by another present moment

... as if Now were some 'thing' with interchangeable parts.

Likewise with:

That almost certainly places a limit on simply believing all present moments are happening simultaneously.

 

The ongoing NOW is not a series of "present moments" and it is not a location/ velocity specific medium, each with a "local now" depending on frame of reference, as relativity of simultaneity would have it.

You say:

Technically-speaking, our present moment, in fact no present moment is really special. You could have an infinite bundle of these present moments and in no way distinguish which present moment most accurately fits the current picture

 

This reifies "the present moment" as if "it" is not only a 'thing', but as if there were a bunch of 'them'... maybe an infinite number of "presents," with one for each locus or frame of reference at whatever relative velocity.

 

Relativity is a theory about local dynamics, but that does not mean that cosmology or time ontology must be so limited.

As I said, concluding my last post in the Ontology of Time thread:

Likewise for "the present." In the big picture (cosmology and ontology of time), relativity's limited, local scope notwithstanding, the present is not limited to reality as observed from local frames of reference.

Edited November 10, 2011 by owl

[Mystery111]

I can't explain it any better than I will now:

 

The present time means ''the present'' - this is going to get complicated.... My sentance saying that the past has a now that is happening is very strange, there is no words which can really describe it properly, but I will try.

 

The past tense can't be just a ''past notion''. It must have a present moment - this is frame-dependant though because we have a ''now'' as well. A way to imagine the present frame of time is by saying each present moment happens in their own frames of reference, they do not happen simultaneously. If it did, reality would be over in one great flash of existance.

 

Instead one present moment must be surpassed by another - this is what is implying by a present moment passing. It does not pass us in any flow, but our frame shifts. We no longer have experience we had of a present moment simply because our frame of reference is moving through time. Saying you can have present moments happening now, is a ''now'' depending on the present and from the frame of the measurer. You can have many present time's, and one way to imagine how you can have an event happening now, but not within our frame of ''now'' is when relativity questions the simultaneity of two events when an observer is concerned.

 

In short, the relativity of simultaneity is concerned if two events actually happened at the time. The answer turns out that the events are not absolute and completely frame dependant. So if two elapsed moments in time for two events [math]A[/math] and [math]B[/math] will not be the same. It is a relative matter. So you can have more than one present moment for two different frames that are ''happening'' - let's be honest, the events are still happening but the real question is whether they will differ on when each event happened.

Edited November 11, 2011 by Mystery111

[owl]

Mystery111,

What part of:

The past has happened. The future will happen.The present is happening.

... do you not understand?

 

Do you understand what reification means? To reify time or the present means to make something, an entity, of it.

 

You say:

The past tense can't be just a ''past notion''. It must have a present moment...

Past tense means over and done, not just a "notion." There is no "it" (reification of 'past tense') to "have a present." Whatever has already happened IS not Now happening, not still present.

 

You go on:...

this is frame-dependant though because we have a ''now'' as well. A way to imagine the present frame of time is by saying each present moment happens in their own frames of reference, they do not happen simultaneously. If it did, reality would be over in one great flash of existance.

 

Did you read my reply in Ontology of Time to Rocket's claim (in 'the present time' thread) that the universal Now is "rubbish?" Relativity addresses local phenomena. The ontology of time (and cosmology in general), including the ongoing present is not so limited, i.e., to to local frame dependent observation. We can consider 'the whole' in cosmology and ontology without automatically invoking relativity's dictum that everything is relative (and depends on frames of reference.) (We can't do that in the Physics section, but we can here.)

Your last sentence above makes no sense. Reality Is ongoing whether we are considering it in part (from different frames of reference) or as a whole.

Saying you can have present moments happening now, is a ''now'' depending on the present and from the frame of the measurer. You can have many present time's, and one way to imagine how you can have an event happening now, but not within our frame of ''now'' is when relativity questions the simultaneity of two events when an observer is concerned.

Consider a cosmos with no observers. Does it change drastically without frames of reference describing different "realities" and different "nows*?" (*As if 'the present' were comprised of many "presents"... as reified entities.)

No. Your paragraph applies only to the limited scope of relativity's local frame dependent descriptions of 'reality.'

 

There is no need for me to go through the rest of your post point by point. The above is the essence of my criticism.

 

You finish with:

It is a relative matter. So you can have more than one present moment for two different frames that are ''happening'' - let's be honest, the events are still happening but the real question is whether they will differ on when each event happened.

It's relative if you restrict the discussion to relativity's frame of reference focus. Please consider for a moment that time is 'that which elapses as all things move everywhere' (as I do) and that the present Is (always) the ongoing now, transcending the 'passage of time' without "frames" around it (as I do.)

Thanks.

Edited November 11, 2011 by owl

[Mystery111]

What part of quantum theory not accepting a past and future don't exist do you not understand?

 

It's not my fault you are still grappling with that idea.

 

Past tense means over and done, not just a "notion." There is no "it" (reification of 'past tense') to "have a present." Whatever has already happened IS not Now happening, not still present.

 

yes from our frame of reference this must be true. Listen, I am very buisy lately. Do me a favour and remove this ''past present future'' nonesense. Your work seems dependant on it.

[owl]

What part of quantum theory not accepting a past and future don't exist do you not understand?

I understand that the past does not still exist now and that the future does not exist yet. What do you think I am missing about what exists now in the above? Grappling?

Do me a favour and remove this ''past present future'' nonesense. Your work seems dependant on it.

 

Your "theory of time" doesn't deal with "this past present and future nonsense?" Have at it.

[Mystery111]

I understand that the past does not still exist now and that the future does not exist yet. What do you think I am missing about what exists now in the above? Grappling?

 

 

Your "theory of time" doesn't deal with "this past present and future nonsense?" Have at it.

 

The past does not exist ''now'' because that would be in direct contradiction with our frame of reference and agreement of what ''now'' is happening. As for ''my theory'' not dealing with a past and future, is simply because there is no past or future to deal with. You seemed intelligent enough to figure this out for yourself, but you seem to have totally went off on a new tangent, most probably based on your own Ontological look of time.

 

It's as I said before, the only way to have a present time is believing that what we call ''past'' is really just another frame-dependant present time. To us, indeed, this is something not happening any more, but this is caused by nothing but being slam dunk in the present moment - The thing we call future is nothing but a present moment.

 

My theory doesn't deal with the concepts of past and future because as we know, as a boundary between our own present time frame is just one big illusion. You can't deal with something which doesn't really exist. If anything, the past and future will only be used by me as a calculational tool but not as real fascets of the physical world.

[Mystery111]

((Note)) --- sorry I made a mistake in the OP. It aint 60 degrees in the turn from real time to imaginary, it's 90 degrees. Just read that and realized what I put there.

[michel123456]

(...) In Prof. Hawking's model, the universe can be modelled under an imaginary time. In this model, you simply shift the way you view evolution. Turning your equations time parameter [math]90^o[/math] you are able to view the universe as though it has no boundaries and thus eliminated the idea that our universe had a beginning.(...)

 

I remember that from a short video with Allan Guth IIRC.

i'll have to search.

 

edit.

I'am afraid IDRC (I don't recall correctly)

Edited November 14, 2011 by michel123456

[Mystery111]

I remember that from a short video with Allan Guth IIRC.

i'll have to search.

 

It's a wonderful model really. In respect to imaginary time alone, you can remove the big bang and the singularity simultaneously. Very interesting model indeed.

[michel123456]

That's what i remembered:

Funny how the camera rotates 90 degrees in the beginning...

[Mystery111]

Yes, nice example by alan. More to the point, and just realized this now, but why is my post in speculations? Most of the points if not the greater majority of them are not based on speculation, but really are part of mainstream?

 

I wonder who moved my post. Thanks Michel, nice thank you.

[tar]

from the outside it looks like it goes on for ever and from the inside it looks like space is infinite?

It's a trade off.

Huh?

 

What does that mean?

 

How exactly does one "get" outside this bubble? And for what reason would anyone "outside" this bubble have any perception of either space or time?

 

If we are "inside" the bubble, and have a perception of space and time, shouldn't we go with it?

 

Regards, TAR2

 

no fair stepping outside the universe. That is "putting yourself" in God's shoes. Can't be done. It's completely imaginary, and anthropomorphising an "outside" view.

 

it would "look like" this or that

humbug

with what eyes would one be seeing what photons. All the eyes and photons there are, are INSIDE the bubble.

[michel123456]

Ha, yes.

The end of the video is superb too.

"and that's it?"

"yes, that's it"

The video ends and nobody understand nothing.