Submitted by KingOfTNT10 t3_10mq4my in space
wjbc t1_j64fakw wrote
There's no such thing. The speed of light is an absolute limit. There's no such thing as time travel, either.
That said, even ordinary light from another star is from the past. If it's 4 light years away it's for years in the past. If it's 100 million light years away it's 100 million years in the past. (Actually, since the universe is expanding, the light we see now is from when the star was 100 million light years away, 100 million years ago -- but at present it would be much farther than that.)
What's not possible is for the light to arrive here any faster than the speed of light, so that we see what's happening now, or more recently than the number of light years between us and that star when the light starts traveling towards us.
LincolnsVengeance t1_j64ggp9 wrote
That's completely not true. There are hypotheses about traveling faster than light and sending signals instantaneously that conform with the laws of physics as we know them, we just don't have the technology to confirm these hypotheses and most likely won't for a very long time. You're also wrong about time travel. Technically speaking, you're time traveling at relativistic speeds due to the effects of time dilation. If you're traveling fast enough, you're time traveling simply because you're experiencing time exponentially slower than people on earth. If you're going to talk in absolutes, I'd encourage you to at least read about what you're going to be talking about first.
Varsect t1_j64j95p wrote
>That's completely not true.
It's not true nor false. You can't conclude one until practical tests have been made.
LincolnsVengeance t1_j64k68m wrote
The statement "there is no such thing" is unequivocally false whether or not you agree with what I said in the rest of my comment. There is such a thing, look up the Alcubierre Drive hypothesis.
Varsect t1_j64kxi2 wrote
What about the Alcubierre Warp Drive?
LincolnsVengeance t1_j64lnju wrote
>It's not true nor false. You can't conclude one until practical tests have been made.
The hypothesis exists therefore there are scientists who at least believe in the possibility that FTL travel is possible. It's also not scientifically impossible, the laws of physics don't forbid it as such. The reason I brought up the Alcubierre Warp Drive is because the person I was commenting to originally made an absolute statement that was wrong. There is a hypothesis therefore it is a thing that exists even if it's not practical theory yet.
Varsect t1_j64njgc wrote
Ok, you've won
>The hypothesis exists therefore there are scientists who at least believe in the possibility that FTL travel is possible
I've always wondered how FTL would help outside of the local group with an expanding universe.
LincolnsVengeance t1_j64o6u3 wrote
You could in theory travel to other stars in our star cluster and explore or even live there if you could find a habitable enough planet. That's so far in the future that it really has no practical application other than as an aspiration and inspiration for those doing the work required to eventual get there. There is the other problem of even at twice the speed of light it would still take 2 years to reach Alpha Centauri.
Varsect t1_j64ox1f wrote
I mean like, that's localized to the Milky Way and the local group. For extra local group travel, it'd basically be impossible.
LincolnsVengeance t1_j64pe2o wrote
I didn't realize you were referring to that kind of scale. I can't imagine it would mean much seeing as the outer edges of the universe are already expanding away from us faster than light
Varsect t1_j64qg42 wrote
Yeah. The fantasy of leaving the local group is basically not realistic and by the time we do learn to do so most of the observable universe will be concentrated almost solely on the edges of the Virgo cluster around Laniakea.
srandrews t1_j64j42g wrote
Your point on time and relativity is a good one. But that should not be called time travel. People colloquially use "time travel" to denote an event that breaks causality. You are probably thinking about nonlocality and entanglement. Those do not transfer information or material in a superluminal manner.
I appreciate your distinction between hypothesis and theory. For at least the sake of our current societal ills, a hypothesis should not be taken as a truth until it becomes a scientifically accepted theory.
LincolnsVengeance t1_j64l20d wrote
I was attempting to keep it less technical because of the nature of the OP's question. I was never arguing that causality breaking time travel is possible. I was just refuting the other commentors absolute statements that there is no such thing. Maybe I had to be creative with my meaning when I say time travel but it's nothing my physics professor wouldn't have done.
KingOfTNT10 OP t1_j64fm6i wrote
Not saying that it exist or will ever exist, but if there was a type of signal that could do it, what would happen?
wjbc t1_j64hegv wrote
Well, since it's an imaginary signal, you can invent what happens.
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