re: Einstein's theory of time, a question.

[Mnemosyne]

What was the exact theory? All time occurs simultaneously.

Any info appreciated.

Thank you!

[The Blue Flower]

1. It was related to rate of speed

As you approach the speed of light, time slows down.

[Birthmark]

2. Basically

That time is relative to the observer. A clock at rest or in zero gravity will measure time differently from a clock in motion or in a gravitational field. (I've forgotten the exact equation.)

[James T. Kirk]

3. If you are driving your car at 99% of the speed of light...

If you are driving your car at 99% of the speed of light and you turn on your headlights, the light will still come out of your headlights at the speed of light. If I'm standing still and see your lights, the light will hit my eyes at the same speed of light. Time and space stretch and compress so that will be true.

I hope I explained that right, if not:
http://en.wikipedia.org/wiki/Theory_of_relativity

[comradebillyboy]

4. its a bit complicated but here's my shot

1. the speed of light is constant for all observers in all frames of refrence
2. if the speed of light is constant, then the rate at which time passes, and the size of things are dependent on the position and motion of the observer.
3. speed is defined as the change in distance divided by the change in time, v=d/t. well if v is constant then d and v must be variable.
4. time and space dialations of objects moving near the speed of light have been observed in the laboratory, so the ideas of special relativity are well supported by experimental observation.

when i was in graduate school i had a job conducting experiments with intense relativistic electron beams.

here are the distance and time relationships
D=d/(1-(v/c)**2)**1/2
T=t/(1-(v/c)**2)**1/2

where D is the legnth an observer sees and d is the legnth of the object at rest. T is the time the observer on earth measures and t is the time a clock attached to the moving object would measure

[smirkymonkey]

5. So if you could (in theory) travel faster than

the speed of light, would time reverse? i.e., could you travel back in time?

[DrWeird]

6. You can't travel faster than light.

According to relativity.

[hunter]

7. It wouldn't matter.

If you go faster than light, time does reverse and you are exactly where you started. Or as Buckaroo Bonzai says, "No matter where you go, there you are."

The equations of relativity do not describe any property of time, because we don't really know what time is; instead these equations relate forms of energy that do not have mass to forms of energy that do. Things that do not have mass always travel at the "speed of light" and thus do not experience time. Things that do have mass interact with one another in various ways that we attribute to a mysterious thing we call "time" relating to a constant we call "the speed of light."

What most of us think of as "time" is a function of our own minds. We all "experience" time so we all know what we are talking about. It's similar to our experience with colors. But imagine explaining colors to a blind person. The physical description of photons and wavelegnths would not be evocative of the experience we call color.

Okay?

[LARED]

8. E=MC^2

A useful way that I think about it is

C^2 (a constant)= E/M. So if the mass changes the energy related to the mass changes and visa versa.

Neat web site

http://www.pbs.org/wgbh/nova/einstein/relativity/

[IrateCitizen]

9. Do you really want the exact theory, or the general concept?

I'm not sure that too many DUers could adequately explain his complete theory of general relativity. But the concepts themselves were pretty revolutionary, and elegantly simple in their mathematical proofs.

Einstein's general theory is based on the idea that the speed of light is constant in all reference frames. It doesn't matter if you're sitting still, travelling at 0.99c in the same direction, or travelling at 0.99c in the opposite direction -- the speed of light (c) is always 3x10^8 m/s. What this, in turn means, is that time and space become drawn out as you approach the speed of light.

The revolutionary part of such a theory is twofold. First, it presents time as a dimension that exists in much the same parameters as length, width and height -- rather than a separate parameter as it was described by classical physicists. This, in turn, allows for the possibility that time can actually be manipulated.

See, Einstein described gravity (in his special theory of relativity, I believe) not so much as a force, but as an actual displacement of space/time. Planets orbiting the sun were actually travelling in a straight line, but the gravity of the sun actually displaced the space surrounding it, forming "grooves" in that space on which the planets travelled.

If you extend such an idea to the dimension of time, then it stands to reason that there are ways to manipulate the nature of time. This, of course, is one of the main topics of discussion in unified field theory, a subject on which Einstein was working at the time of his death, which proposes that there are actually as many as ten dimensions.

This discussion is really a pretty significant can of worms you've opened up here. Einstein's theories are not the be-all, end-all -- but they were revolutionary enough in themselves to take the field of physics into new and exciting directions. It is in talking about these new and exciting directions that the REAL discussion lies.

If you're truly interested in these concepts, I'd recommend you check out the book Hyperspace by Dr. Michio Kaku. Kaku is excellent at discussing complex physical concepts in terms that people with a basic understanding of some mathematics and physics can easily understand. He also has a new book out, Einstein's Cosmos, which I haven't read yet.