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sk8rpinoi32
2008-Feb-13, 06:19 AM
In Astronomy Cast Ep: 74 they mentioned that anti-matter doesn't exist within "anti-time." And in fact, the female voice of the show says that anti-time doesn't exist (she jokingly says that anti-time is running the clocks backwards). The problem I have is grasping the non-existence of anti-time when Richard Feynman through his diagrams shows that antimatter particles exist backwards in time.

I don't entirely understand what that means, but the way I interpreted it is that the existence of the particles is already laid out. Think of a time line (flowing left to right as time progresses). At point 1 is the creation of matter and anti-matter. (0-1 exist only energy in the form of photons) At point 10, the two particles collide and points 10-11 is the same photon from segment 0-1. So it looks like this ----==========----. The equal sign is the matter and antimatter particles, the dash is the photon. So a normal particle exist left to right. An antimatter particle exist right to left.

I don't mean to be condescending. I do understand that the world of astronomy and physics is too large and constantly changing for one person to know everything.

BigDon
2008-Feb-13, 08:49 AM
I was given to understand that anti-time is analogoes to negative numbers. Not real, but useful in the maths of the beginnings of the big bang.

BigDon
2008-Feb-13, 08:50 AM
Oh, and welcome to Baut. I didn't see you were new.

sk8rpinoi32
2008-Feb-13, 09:22 PM
Ummm, I don't know if antitime is negative, at least not according to the Feynman Diagrams.

sillybear7
2008-Feb-17, 02:42 AM
The Feynman Diagrams has anti-particles as particles that travel backwards through time, with the same properties as thier 'normal' counterparts.

The matter/anti-matter relation is such that when they get together they annihilate each other in a flash of energy. Thus I would be led to believe that anti-time is some how the arch nemesis of time in that they too would annihilate each other when they met. However time is not a particle, just like space isn't. So talking about anti-time is like talking about anti-space, I don't think that either of these things exist even as mathematical 'tools'.

sk8rpinoi32
2008-Feb-17, 05:11 AM
Well you'd have to look at it at a "time to space diagram" standpoint. Anti-space would be an object moving down the x-axis. Anti-time would be something moving left of the y-axis. Anti-matter particles travel to the left. Does that help?

3dknight
2008-Feb-17, 09:29 AM
Um welcome sillybear7 and sk8pinoi32. What is time in the first place? I thought time is just something we created to make sure everyone was on the same schedule. The advancement of the universe? is that time?

Steve Limpus
2008-Feb-17, 07:20 PM
Um welcome sillybear7 and sk8pinoi32. What is time in the first place? I thought time is just something we created to make sure everyone was on the same schedule. The advancement of the universe? is that time?

I think we have to consider time as a 'something' rather than as just an abstract way to descibe a sequence of events. Relativity tells us time is a property of the universe, it can slow down or speed up, it's a co-ordinate in space-time just like Auckland is a location in New Zealand. You couldn't find me in the universe without knowing my time. It's a real thing I think.

Anti-time - I haven't got a clue!

Just my $0.02.

Steve Limpus
2008-Feb-17, 07:58 PM
This is what Lee Smolin says here:

http://www.fortunecity.com/emachines/e11/86/whattime.html


"So, what is time? Is it the greatest mystery? No, the greatest mystery must be that each of us is here, for some brief time, and that part of the participation that the universe allows us in its larger existence is to ask such questions. And to pass on, from schoolchild to schoolchild, the joy of wondering, of asking, and of telling each other what we know and what we don't know."

Whoa.

fourmanifold
2008-Feb-21, 09:39 AM
The problem I have is grasping the non-existence of anti-time when Richard Feynman through his diagrams shows that antimatter particles exist backwards in time.


First of all, I don't think that "anti-time" is the same with "backwards in time". Even more, I don't think that the concept of anti-time makes any sense if "anti-" is used in the same sens as in "anti-mater".
As sillybear7 said

... However time is not a particle, just like space isn't. So talking about anti-time is like talking about anti-space, I don't think that either of these things exist even as mathematical 'tools'.
Matter of fact they don't exist. Time is part of space-time and matter is a completely different stuff! Time, in a sens, is the 4th axis in a 4-dimensional "space" (3+1-dimensional space-time to be more precise).
So if you define "anti-time" to be "backwards in time" it's starting to make sense, but you will still be dealing with the classical concept of time (the orientation will be different).
So the analogy made by BigDon between "anti-time" and negative numbers is at an intuitive level correct. It is telling you that "thinking" at anti-time you are dealing with the same thing (the time-line). Just the direction will be different.