Would An Object Travelling At The Speed Of Light Experience Time Or Space?

[Maine farmer]

This has been keeping me up at night. If time stops at the speed of light, wouldn't an object travelling at the speed of light percieve itself to be everywhere in it's path in an instant? If you were to travel the entire universe at the speed of light, would not the entire universe seem to be a single point?

[Qfwfq]

would not the entire universe seem to be a single point?

More like a single plane.

 

However, it doesn't make all that much sense to try and imagine it. For one thing, a composite body couldn't really experience anything during the journey, whereas a single elementary particle probably never experiences anything at all. For another, there would be no time to experience anything.

I sleep much better at night if I imagine I'm stroking Claudia Schiffer. :wink:

[Maine farmer]

Right, of course you can't experience anything in zero time, so traveling at the speed of light, although alegedly impossible, would be equivalent to traveling through a hypothetical wormhole, would it not? Then again, if you were to reach the speed of light, you would never be able to stop either, unless something stopped you. I guess it would be more fun to dream about Claudia.

[Qfwfq]

You could imagine being at speeds increasingly nearer to c and work out all the Lorentz transforms, but it would be tricky to predict every detail. The nearer your speed is to c, the less time elapses for you to reach the same star from here and of course in your coordinates the distance is correspondingly shorter. You would also witness optical effects as you look at the stars, including blueshift ahead and redshift behind. Tricky enough to work everthing out. Claudia will soothingly tell you about the increasingly red and blue colours, without saying that eventually you would get only microwaves from the things behind you and UV, X and gamma rays from things forward.

 

would be equivalent to traveling through a hypothetical wormhole, would it not?

That's a much more complicated thing. If you asked Claudia about that she would leap out of bed and go running off, before even thinking to get dressed.

 

I guess it would be more fun to dream about Claudia.

Hmmmm, maybe not more fun, actually. Just that it's a lot better for getting a good night's sleep! B)

[Mr. Scientistic]

Time is not completely separate from and independent of space as you would ordinarily assume. In his Special Relativity theory, Einstein assumed that the fundamental laws of physics do not depend on your location or motion. Two people, one in a stationary laboratory and another in a laboratory aboard a train or rocket moving in a straight line at uniform speed, should get the same results in any experiment they conduct. In fact, if the laboratory in the train or rocket is soundproof and has no windows, there is no experiment a person could conduct that would show he/she is moving.

 

The laws of physics include the laws of electromagnetism developed by James Maxwell and Maxwell found that electromagnetic waves should travel at a speed given by the combination of two universal constants of nature. Since the laws of physics do not depend on your location or motion, Einstein reasoned that the speed of light will be measured to be the same by any two observers regardless of their velocity relative to each other. For example, if one observer is in a rocket moving toward another person at half the speed of light and both observers measure the speed of a beam of light emitted by the rocket, the person at rest will get the same value the person in the rocket ship measures (about 300,000 kilometers/second) instead of 1.5 times the speed of light (=rocket speed + speed of beam of light). This assumption has now been shown to be correct in many experiments. To get the same value of the speed (= distance/time) of light, the two observers moving with respect to each other would not only disagree on the distance the light travelled as Newton said, they would also disagree on the time it took.

 

Einstein found that what you measure for length, time, and mass depends on your motion relative to a chosen frame of reference. Everything is in motion. As you sit in your seat, you are actually in motion around the center of the Earth because of the rapid rotation of the Earth on its axis. The Earth is in motion around the Sun, the Sun is in orbit around the center of our Galaxy, the Galaxy is moving toward a large group of galaxies, etc. When you say something has a velocity, you are measuring its change of position relative to some reference point which may itself be in motion. All motion is relative to a chosen frame of reference. That is what the word ``relativity'' means in Einstein's Relativity theories. The only way observers in motion relative to each other can measure a single light ray to travel the same distance in the same amount of time relative to their own reference frames is if their ``meters'' are different and their ``seconds'' are different! Seconds and meters are relative quantities.

[Maine farmer]

You could imagine being at speeds increasingly nearer to c and work out all the Lorentz transforms, but it would be tricky to predict every detail. The nearer your speed is to c, the less time elapses for you to reach the same star from here and of course in your coordinates the distance is correspondingly shorter. You would also witness optical effects as you look at the stars, including blueshift ahead and redshift behind. Tricky enough to work everthing out. Claudia will soothingly tell you about the increasingly red and blue colours, without saying that eventually you would get only microwaves from the things behind you and UV, X and gamma rays from things forward.

 

That's a much more complicated thing. If you asked Claudia about that she would leap out of bed and go running off, before even thinking to get dressed.

 

Hmmmm, maybe not more fun, actually. Just that it's a lot better for getting a good night's sleep! B)

The thought just popped into my head that it could be possible that Claudia Shiffer is secretly a genius in theoretical physics, for all we know. We don't want to do any stereotyping.