# Greene's Fabric of the Cosmos

1. Oct 25, 2008

### kkapalk

I would just like a couple of opinions on a subject I read in Brian Greene's Fabric of the Cosmos. He states that all of time exists. Every event that has happened or will ever happen exists in its own time line. For instance while I write this at the age of forty two the event when I take my first steps as a toddler also exists, as does the event when I am a seventy year old sat in my rocking chair. What do other people on this site think of this? I am really fascinated by it. What I do find hard to accept is, how can I exist as a seventy year old when the events have not yet unfolded to allow this to be true?
One thing I do find very odd about time is the present, the tense which should be the most straight forward. I may seem a little confused here but this is how I see it: Every event in spacetime can be infinitely divided down when examined so none of it actually exists in the present. I do realise that events cannot last for any length of time otherwise they would just be repeating themselves. Obviously when, say, a footballer races across the pitch and scores a goal this event can be said to exist for a minute or so, but when examined each specific moment and each specific distance covered can be divided down infinitely. So at no time could we choose any particular moment and call it the present, because no matter how short a time and how small a distance we try to call 'the present', this moment or distance can be divided down into part past and part future. It seems to me the present is merely an illusion and all we have is past and future meeting at a point. There is definitely something odd going on in my view, I just cannot seem to work out what! Sorry if this seems confusing, any replies will help.
Kev

2. Oct 25, 2008

### matheinste

Re: time

Hello kapalk.

Quote:-

---Every event that has happened or will ever happen exists in its own time line.----

I don't think that statement is true. Your reading this post, an event, has not yet happened because you do not even know i am replying to your question. I may or may not hit the Post Quick Reply button, who knows!

Matheinste.

3. Oct 25, 2008

### kkapalk

Re: time

I agree with what you say, but Brian Greene appears not to!

4. Oct 25, 2008

### matheinste

Re: time

Hello kkapalk.

Perhaps you could give the exact words of Greene. There may be a problem with interpretation.

Matheinste.

5. Oct 25, 2008

### Gib Z

Re: time

This sounds like just a little twist on the Many - Worlds interpretation of Quantum Mechanics. It doesn't sound as wacky when you take it from that viewpoint.

6. Oct 25, 2008

### atyy

7. Oct 25, 2008

### kkapalk

Re: time

Why would there be a problem with interpretation? I do not have the book at the moment as I have just lent it out, but basically he states that all events in time do exist because if someone many millions of miles away who was on the same time frame as us suddenly got up and walked in a particular direction then he would be hundreds of years into our future time frame or our past time frame ( I am not sure which). Please read the book, particularly the frozen river chapter, for a better description than I can give. All this is pretty deep for me, but I am sure of what I read and it does warrant reading.
Kev.

8. Oct 25, 2008

### kkapalk

Re: time

Atty, I did not say it does. That was just Greene's theory. I found it hard to understand too. But being as he is a well respected scientist surely his idea is worth looking at and commenting on.

9. Oct 25, 2008

### matheinste

Re: time

Hello kkapalk.

Two observers moving relative to each other may see things differently, but these things will have already happened. Two observers in relative motion will disagree as to what time an event happened. Check out the Andromeda paradox and read up on the relativity of simultaneity. Most problems/paradoxes of this nature are due to a misinterpretation ( for effect or for a teaching illustration sometimes deliberately ) of this mechanism.

Matheinste.

10. Oct 25, 2008

### atyy

Re: time

I thought he was giving the completely standard answer, and I was just pointing you to something to read about it. If he was giving his own ideas, then I guess he was talking about something different.

11. Oct 25, 2008

### atyy

12. Oct 25, 2008

### matheinste

Re: time

Hello kkapalk.

I have just read a few pages of Greene's The Fabric of the Cosmos - Space, Time and the Texture of Reality. I read the start of chapter 5 - The Frozen River. I have not had much time to study it, but all these things appear in most popular Relativity non-textbooks.

It needs careful reading and thought to see what is really being said. It does require some thought on the part of the reader as it is very easy to get the wrong idea. Greene is not disagreeing with mainstream Relativity, just attempting to make it more interesting as a casual read. No harm in that, my interest started from reading such books, but when you ask more detailed questions you find that although he is correct, your, or my idea of what he is saying is in fact NOT what he is actually saying. He is not misleading us, it is just us being a little lazy with our thoughts.

Matheinste.

13. Oct 25, 2008

### Staff: Mentor

Re: time

This is essentially the point addressed by atyy's first link. According to that author you can have a 4D spactime and a physical "present" as long as you discard any notion of distant simultaneity. Since simultaneity is a relative and non-physical notion, it shouldn't be too difficult to discard if you are uncomfortable with getting rid of the present.

14. Oct 26, 2008

### Primordial

Re: time

I understand Greene's point of view, however if one makes that walk the continuum would then be changed.[/I]

Last edited: Oct 26, 2008
15. Oct 28, 2008

### Egor50

Re: time

I don't know, (Who does?) but the more I think about time, I think it really doesn't exist in nature. Space is so seemingly interconnected with it due to the fact that there is no way to to traverse space in the minutest, or the most expansive, without spending time to do it. Think about how almost "one" they are! Down to the most infinitesimal disturbance of motion in space it will take some time to do it. Yet what happens when there is no motion? is time still passing? Time is relevant to change as we understand it. If nothing changed ever...how much time would pass? You see that is why time as a human concept can not be forgotten. Suppose time can only exist as a product of memory? that would explain a LOT of its seemingly unfathomable mysteries and paradoxes. Think (and I don't think we can truly separate ourselves from our thought processes) for a moment if you really could not remember? Then suddenly without years, weeks, hours, minutes, seconds, and fractional divisions thereof..as a reference where would we be looking from? You would be? Where? at what reference point would you then "see the universe" from? There would be no past for you to recall! Its relativity again. we seem to live in a tense of constant refreshing. instant to instant.(And I ain't even touching the future tense here!) And as we do that the matter and energy play itself out in a seemingly probabilistic restructuring in that for those instances we get some sense of. Its all ties up into what we are. Look at it this way: Lets assume some theory of unification becomes real ok? Now that says everything is one thing. that means everything and I mean EVERYTHING subsets from that. So whats all the differences we see in the universe? its physical differences in properties Google s of them! Time is what separates all those differences. And here we are! That's as far as I can take it in text. Until we can really define in these "golden days" of discovery what the universe really is, we'll have to just exist in awe taking "plank time" steps towards the description that ultimately makes physical sense to our consciousness. Time, Motion, Gravity, Space, all seem to become one if you think about it quantitatively.

16. Oct 28, 2008

### Legion81

Re: time

That was one of several answers I came up with after thinking about Zeno's paradox. I'll have to check out that book.

17. Oct 29, 2008

### Phrak

Re: time

Originally I was going to tell you this just just sloppy language. Something I've been guilty of, on this very point. Add to that a notion of mechanical determinism disregarding the evidence of quantum mechanics.

There is a tendency to visualize all of spacetime as sitting in front of you, layed out. There's nothing wrong with this. But when you start talking about the map, instead of the physics, your verb-tense can go wrong.

"Will be" becomes "is". "Has been" becomes "is".

I don't think that Greene had the luxury to get hit up-side the head and told to stop scrambling verbs leading to contraditions.

Last edited: Oct 29, 2008
18. Oct 29, 2008

### atyy

Re: time

I just came across the strangest paper to do this, but QM, not relativity! What do you make of it?

"The “destiny-generalization” of QM inspired by TSQM posits that what happens in the present is a superposition of effects, with equal contribution from past and future events." Aharonov and Tollaksen, New Insights on Time-Symmetry in Quantum Mechanics http://arxiv.org/abs/0706.1232

19. Oct 30, 2008

### Phrak

Re: time

Thanks for the article! I'll give it a look. That's, in general, what I've been working on, and where any arrows of time are induced only by the thermodynamic evolution of the universe.

Maybe I should have said "disregarding the apparent evindence of quantum mechanics." Bare bones quantum mechanics is not explicit on equating any sort of measurement operation with a preparation process.

Last edited: Oct 30, 2008
20. Oct 30, 2008

### GTOzoom

Re: time

The problem I see with zeno's paradox is that he is trying to make a finite description of an infinite event. Yes, if you try to measure time as a non-continuos function you have some difficulty but thats because you are replacing continuous time with an interval-driven time, which is not the case. Its like trying to represent a quadratic equation with a single linear function. It might be true at one point, and if you change the linear equation(equal to changing your location at a given time) it becomes true at another point, but that makes the first assumption false. You cannot represent time finitely because it is infinite. Sorry if my description doesn't help you, im having trouble representing my thoughts in words.