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Is Faster-Than-Light Travel or Communication Possible? (1997)

math.ucr.edu

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Re: Is Faster-Than-Light Travel or Communication Possible? (1997)

#41

Post by sevenless »

kirykl wrote: post #40
api wrote: post #21

Earlier quoted context omitted.

We've only been doing this science thing in a serious organized way for between 100 and 200 years depending on how you count it. It's only since WWII that we've done it in a really big heavily funded way (cold war and all that). You're probably right, but I can't bring myself to be quite as dogmatic about it. I do very much doubt FTL, not only for the physics reasons but for other circumstantial ones. If FTL is possi…

if a method to violate causality is discovered on Earth it probably wouldn't lead to intelligent expansion, but mass destruction

I wouldn't worry; we can't agree what causality actually is, or whether it even exists, let alone what would constitute a violation of it.

Re: Is Faster-Than-Light Travel or Communication Possible? (1997)

#42

Post by sevenless »

3pt14159 wrote: post #23
snarfy wrote: post #12

Earlier quoted context omitted.

The center of the galaxy is 32,000 light years away. 32,000 years will have passed at the center of the galaxy by the time you get there in your 3.2 second journey. If you then turn around and go back, another 32,000 years will have passed before you get home. It might feel more like time travel than space travel.

This is one of my theories about why there isn't any alien life around. There is some party far in the future with a beacon or message that shouts "JOIN US HERE IN THE MIDDLE OF GALAXY R345Q2 10 BILLION YEARS IN THE FUTURE!" After about 10 thousand years of hearing the beacon and being alone we finally get restless and just build a couple thousand giant spaceships and join the rest of the universe in the most cosmopo…

> This is one of my theories about why there isn't any alien life around.

Do we need a theory on this yet? I mean... out of all the planets we've explored reasonably thoroughly so far, 100% have had life at some point.

Re: Is Faster-Than-Light Travel or Communication Possible? (1997)

#43

Post by amelius »

jerf wrote: post #35
amelius wrote: post #34

Earlier quoted context omitted.

Well, the people standing by watching the experiment still notice you are moving slower than light.

How does that relate to your first post? Are you really focusing on what people notice?

Yes.

Re: Is Faster-Than-Light Travel or Communication Possible? (1997)

#44

Post by dcherman »

snarfy wrote: post #12
sevenless wrote: post #7

The thing is that subjectively "FTL" travel, a la Star Trek, is totally possible thanks to special relativity contracting distances between objects. A little math shows the relative velocity in which you travel one light year measured in a rest frame, in one year in your spaceship's frame, is 70.7% of the speed of light. If you happened to be moving at the ludicrous speed of the "Oh-My-God" cosmic ray recorded in 199…

The center of the galaxy is 32,000 light years away. 32,000 years will have passed at the center of the galaxy by the time you get there in your 3.2 second journey. If you then turn around and go back, another 32,000 years will have passed before you get home. It might feel more like time travel than space travel.

What I've always found interesting (not sure if there's a name for this) is kind of the idea that if you made such a trip, you might find by the time you arrive there in 3.2 seconds, the rest of humanity has figured out true FTL travel with the technology that was developed during those 32,000 years. As a result, you arrive in what might be the equivalent of a horse and buggy at the center of the galaxy versus what everyone else is riding around in.

Re: Is Faster-Than-Light Travel or Communication Possible? (1997)

#47

Post by mariodiana »

jandrese wrote: post #17
aaron695 wrote: post #16

Thinking you can go faster than light for communication is the same as believing perpetual motion or even being a flat earther. You can't do it, there are no hacks to do it. It's a law of the universe. No matter how many SciFi movies tell you other wise. I just don't get the acceptance of this anti-scientific concept.

This is exactly right given our current understanding of the universe. FTL travel violates causality, which is a fundamental principle of the universe. I wouldn't go quite so far as to say it's totally impossible though. There is a whole lot about the universe we don't understand and I can't rule out the possibility that there are entire branches of mathematics and physics that we don't know about.

Can you or someone else "explain to me like I'm five" why faster-than-light travel violates causality?

Re: Is Faster-Than-Light Travel or Communication Possible? (1997)

#48

Post by zxexz »

3pt14159 wrote: post #23
snarfy wrote: post #12

Earlier quoted context omitted.

The center of the galaxy is 32,000 light years away. 32,000 years will have passed at the center of the galaxy by the time you get there in your 3.2 second journey. If you then turn around and go back, another 32,000 years will have passed before you get home. It might feel more like time travel than space travel.

This is one of my theories about why there isn't any alien life around. There is some party far in the future with a beacon or message that shouts "JOIN US HERE IN THE MIDDLE OF GALAXY R345Q2 10 BILLION YEARS IN THE FUTURE!" After about 10 thousand years of hearing the beacon and being alone we finally get restless and just build a couple thousand giant spaceships and join the rest of the universe in the most cosmopo…

Huh, this is a really fun thought experiment. Does anyone know any scifi books that explores this (or a similar) concept?

Re: Is Faster-Than-Light Travel or Communication Possible? (1997)

#49

Post by blackkettle »

aaron695 wrote: post #16

Thinking you can go faster than light for communication is the same as believing perpetual motion or even being a flat earther. You can't do it, there are no hacks to do it. It's a law of the universe. No matter how many SciFi movies tell you other wise. I just don't get the acceptance of this anti-scientific concept.

I don't get the thought process that locks this possibility out. Imagine you are a simulated entity inside simulated universe - v100000 of Eve Online.

There are rules that you can see and access, and those you cannot. Both are in some sense irrelevant to your own perception of truth because they are determined outside the bounds of your empirical experience.

What good evidence do you have to refute such an explanation [surely its likelihood increases in line with our own ability to create the 'next turtle down'].

Re: Is Faster-Than-Light Travel or Communication Possible? (1997)

#50

Post by sliverstorm »

sevenless wrote: post #7

The thing is that subjectively "FTL" travel, a la Star Trek, is totally possible thanks to special relativity contracting distances between objects. A little math shows the relative velocity in which you travel one light year measured in a rest frame, in one year in your spaceship's frame, is 70.7% of the speed of light. If you happened to be moving at the ludicrous speed of the "Oh-My-God" cosmic ray recorded in 199…

That bit about the particle is fascinating, but I am struggling to understand why a particle that travels at 0.99x of the speed of light is faster than a ship that travels at 1516x the speed of light. Is the Star Trek universe not subject to time dilation?
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