Faster than light travel impossible

[James S]

[James S]

oh oh oh, okay. I understand the lightbulb in the spaceship thing now. Because he [the man outside the spaceship] is in a different location and has a different speed his reference to simultaneality, things that happen at the same time, will be different! That's pretty neat. It's like everyone has their own point of view on the universe.

[jongjungbu]

[Robotbeat]

Thank God for Brad, saying the first sensible thing in this conversation!

you can't move faster than the speed of light. But if you did, then time might go backwards (which doesn't make sense, and offers a lot of paradoxes, so it's probably not possible for any particle or radio/microwave/heat/infrared/light/ultraviolet/xray/gamma ray beam to go faster than c). Basically, if anything seems to violate the law of no partical or light going faster than c, then time/length contraction/dilation is likely in the mix.

However, it is apparently possible to send a signal faster than the speed of light through a cloud of cesium vapor (under specially controlled conditions). This is possible because the cesium cloud actually like absorbs the light and transmits it at the other end, so that the signal reaches the end of the cesium chamber faster than it would in a vacuum. It's kind of weird. Remember, the speed of light is constant in a vacuum.

Another reprocussion of relativity is that if you start adding more energy (that would normally cause it to accelerate) to a particle when it's very close to c, it does indeed make it go a little bit faster, but the object seems to become more massive, in order to conserve momentum and obey energy laws (i.e. thermodynamics).

For reference, c is a little less than 300,000 km per second, or about 670 million miles per hour.


Just so you know, someone said something like this: "If you were in a closed capsule, then you couldn't tell how fast you are going, unless you accelerated."
Well, if you were in a closed capsule, you also couldn't tell if you were accelerating or if it was just the force of gravity. One of Einstein's theories says this (I forgot which one). Basically, you can't tell the difference from the effects of gravity and the effects of acceleration with any internal experiments. Basically, he was saying that gravity isn't a force force, anymore than acceration itself is a force (acceleration is a result of a force, generally). If you feel gravity, that's just the force of the ground acelerating you upwards, which is a force pushing you against the natural curve of space around objects of mass. Einstein said that gravity is just the curvature of space in the presence of mass.

Anyways, if that doesn't make any sense, Moose, then just pick up a book from the library about Relativity. They have some really easily understood books, like those at a Junior High level. I remember reading books like that in elementary school...

Kudos from another Physics nerd... (wanted to be a scientist from Kindergarten, a physicist since before 5th grade).

I will learn even more in this coming semester. I'm a Physics major at Bethel College. My professor this coming Spring semester, Professor Peterson, was just elected president of the association that publishes the American Journal of Physics, the most highly-read physics journal/magazine in the world. He's a really nice guy... He helped me set up one of his lasers to measure the muzzle velocity of my potato cannon... hehe...

[Robotbeat]

BTW, there are lots of ways around Relativity and stuff like that. For instance, you could always just shrink the space in front of you and expand the space behind you. But that requires a heck of a lot of "negative energy". You also need a lot of negative energy to keep a wormhole from collapsing in on itself (yes, they are possible, just not for very long). I don't mean antimatter when I say negative energy... Basically, you can't have a lot of negative energy for a decent amount of time. You can either have a bunch of negative energy for a very, very short time or you can have a little, tiny teeny bit for a long time. That's just another way of saying that it will never happen. Negative energy is weird... Having a lot of it basically starts violating the laws of thermodynamics, so it is pretty useless for most of the time.

The premise of negative energy is that in normal, completely "empty" space (which contains a net energy of zero, basically it's a dark vacuum with no radio-waves or nothing), there are still these phantum particles which are never really there, but sort of fade in and out of existence. If you can find a way to get rid of these "phantum particles", then you basically have a "negative" net amount of energy. Some experiments have shown that these phantum particles can be somewhat dampened in the vacuum between two metal plates (again, special controlled circumstances) because there is a very slight outward force exerted from inside that can only be accounted for by a "negative" energy that pushes outward, instead of inward (like gravity pulls you inward). Unfortunately (but maybe fortunately?) and understably, this is an extremely small amount of negative energy. Anyways, this is beyond my league (I haven't actually studied this in class, whereas the Relativity I sort of have). I mean, I don't know the math and theory behind all this, but I do for Relativity, at least to some extent. See ya in a year when I have this all figured out.

[James S]

[Paul]

[sandmann]

[James S]

[RICoder]

[James S]

[RICoder]

no, you made cursory reference to it, but it was inacurate.

[James S]

cursory references were enough.

Why do you have to be so critical? We're having a casual conversation here. Just lighten up. You're such a freak.

[RICoder]

because someone might read it and then go off and think that time travel is possible and base their argument on what you wrote...and that would disturb me in some deep way.

[abannedguy]