Time Travel : Is it possible?

[gy2020]

Yes, but you're still in the same medium, air. When you dive you are in water, which slows the transmission of light. Of course it could just be that you are having a good time and time seems to speed by when you are enjoying yourself and slows to a stand still when you are bored or doing something you don't like. I wonder if anybody has ever studied this effect of water and air?

[Tek_Freek]

Originally Posted by mattpoulsen

Prince,

Past events by either clock! The effect you're talking about is nothing more than a "time of flight" problem. It really has nothing to do with relativity, other than the fact that the speed of light is constant.

Not.

Putting the Brakes on Light Speed - washingtonpost.com

[Prince of Lombards]

Originally Posted by gy2020

I just created another thread, not realizing this one was here. I'll post the same question. I use to be a SCUBA diver and it always seemed that I was underwater for just a few minutes, only to find that I had been diving for 20 to 30 minutes. Other divers had same experience.
last night I was watching The Universe on History channel and Dr. Mallett is working on time travel using light as source of energy. The program stated the light travels slower in water than it does in air.
Could the difference in light speed correlate with my experience?

It's only coincidental without any causality relationship. The reason for the distortion of time underwater has to do with somethng else (more of a psychological reason, but I'm not sure what).

[gy2020]

I'm sure it probably has more to do with being consumed with interest and you lose context of time. When your bored with nothing to do and you watch your clock it creeps by slooooooooooowwwwwwwllllllllllyyyyyyyy. I just thought it was interesting that Mallott is working on time machine and using light as source of energy and the program brought up movement of light in atmosphere and water.

[mattpoulsen]

Umm no! While light does travel slower in water than in air or vacuum the difference is not something you could possibly notice. Furthermore, time isn't running slower in water anyway...the speed is light is reduced. I would also add that the light travels through ANY medium slower than it does in vacuum. This isn't a ground breaking idea. In fact, its something that manifests itself eveyday. Ever hear of Snell's Law? At any rate, is the reason that images at the bottom of a pool appear "displaced" relative to their actual position.

[mattpoulsen]

Tekfreek,

The speed of light in vacuum is constant. As far as light through a medium everyone who has taken a high school physics course knows its slowed in a medium. Yes, there is some remarkable research that is working to "nearly stop light" (in fact I know a few guys in that area of research). However, this is a subtle issue that without a background in physics the general public usually just glosses over. It has to do with the difference between phase velocity and group velocity.

At any rate, speed of light being constant is one the essential elements of the special theory of relativity. And within the context of S.R. the speed of light is absolutely constant.

[GENO-777]

Bet most of you are from the 60's, and you smoked to much weed.

[Tek_Freek]

You can never smoke too much weed, dude.

[Tek_Freek]

Originally Posted by mattpoulsen

Tekfreek,

The speed of light in vacuum is constant. As far as light through a medium everyone who has taken a high school physics course knows its slowed in a medium. Yes, there is some remarkable research that is working to "nearly stop light" (in fact I know a few guys in that area of research). However, this is a subtle issue that without a background in physics the general public usually just glosses over. It has to do with the difference between phase velocity and group velocity.

At any rate, speed of light being constant is one the essential elements of the special theory of relativity. And within the context of S.R. the speed of light is absolutely constant.

Your initial post did not contain the word vacuum.... or context... or a bunch of other terms found in this one.

And I question the validity of S.R. Usually when I'm smokin'.

[mattpoulsen]

I don't need to qualify the "speed of light." If you actually understood S.R. then you understand that the observed slowing of light in matter is not a violation of S.R. and does not deem the speed of light not to be constant. Do you know the difference between phase velocity and group velocity? If you do then I don't need to qualify whether the light is propagating "in a vacuum or in air."

Anyway, this conversation has lost any shred of seriousness. I'm done.