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Warp Drive May Be More Feasible Than Thought, Scientists Say

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Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

#41

Post by nessus42 »

CWIZO wrote: post #10

As much as it pains me to say this, but I think we have to invent some more advanced weapons before we start poking our heads out of our galaxy. Don't get me wrong, this is fantastic and I'm all tingly from excitement (this is the first time I've read about warp drives in the context of real science) ... but like I said, taking a stroll trough the galaxy with our bombs and finding a hostile alien world. Well we'd be…

Fear not. Despite the science behind the OP, faster than light travel will not turn out to feasible. Those who think it will be, haven't really thought through the ramifications of what a world in which causality is routinely violated would be like.

Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

#42

Post by adastra »

CWIZO wrote: post #10

As much as it pains me to say this, but I think we have to invent some more advanced weapons before we start poking our heads out of our galaxy. Don't get me wrong, this is fantastic and I'm all tingly from excitement (this is the first time I've read about warp drives in the context of real science) ... but like I said, taking a stroll trough the galaxy with our bombs and finding a hostile alien world. Well we'd be…

For anyone interested in the (just for fun) topic of technological advancement, weaponry, and encounters with other civilizations, you should check out Vernor Vinge's Zone of Thought novels, a Fire Upon the Deep and A Deepness in the Sky. I can't recommend them enough.

In particular, he assumes that all civilizations will follow roughly the same arc of technological discovery, and that once they hit their information age, it's all about computational power and software. Which, of course, expand in power exponentially with time.

As for us explicitly preparing for that kind of encounter, sorry but if we run into hostiles we're screwed. Take any tech of your choosing and extrapolate. For example, a civilization a few hundred years more advanced than us could easily hit Earth with a custom-made virus or nanobots and wipe out humanity in a day. And if they were a few hundred thousand years more advanced? Impossible to say, but I think our only hope is think that we're too low-level for them to bother messing with.

Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

#43

Post by palmtree3000 »

goldfeld wrote: post #38
johnnymonster wrote: post #18

How about we first build a space ship that travels anywhere near the speed of light?

I assume travelling near speed of light with conventional physics is impossible, since the ship's mass would crush itself as it increased infinitely. Warp drives, on the other hand, seem to work by moving space-time, not the ship. So in theory the ship is left intact, without the people inside feeling any acceleration whatsoever.

I'm fairly certain that wouldn't be an issue. Relativity means that any (let's say non-accelerating, to keep us within the context of special relativity) reference frame is just as good as another. In the spacecraft's reference frame, it's chilling out, and a bunch of stars off a ways are moving really fast, but they don't really affect it.

It is an interesting problem though; I'm not really sure why it can't crush itself...

Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

#44

Post by geuis »

nessus42 wrote: post #35

You can't have faster than light travel without violations of causality. And while the equations of General Relatively allow for universes where causality is routinely violated, the probability that we are in such a universe seems vanishingly small. E.g., just because you can violate causality does not mean that you can go back in time and kill your grandfather. If you were to try, something would stop you, as a univ…

We aren't talking about time travel. So many people confuse the idea of FTL with time travel. General Relativity talks about frames of reference.

Suppose you had a base on Mars and sent a radio signal to it from Earth. It would take between 4.3 to 21 minutes to reach Mars, depending on its distance from Earth at the time.

If you simultaneously jumped in your 10x warp drive and set out, you would arrive at Mars in 25.8 seconds to 1min 26 seconds, again depending on distance.

In this scenario, there has been no violation of causality. You aren't arriving before you sent your radio signal. All that is happening is that you're arriving before your radio signal does. From the perspective of a telescope or radio antenna at the Mars base, you would view Earth in its state 4.3 to 21 minutes before, because it simply takes that long for the electromagnetic waves to get to you.

So yes, you can travel faster than the speed of light without violating causality. If you travel in a relativistic way, i.e. speed all the way up to 99.99999% of light speed, you will most certainly run into time slowing down in your local frame, while it continues at a normal frame back at your departure point.

But with a warp drive that works as described in the article, there is no changing of reference frames. Since you're warping space itself, the spacecraft isn't actually undergoing acceleration in the relativistic way of a rocket. For passengers on board, the clocks are going to run at the same rates as back home.

Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

#45

Post by stan_rogers »

nessus42 wrote: post #35

You can't have faster than light travel without violations of causality. And while the equations of General Relatively allow for universes where causality is routinely violated, the probability that we are in such a universe seems vanishingly small. E.g., just because you can violate causality does not mean that you can go back in time and kill your grandfather. If you were to try, something would stop you, as a univ…

Causality, though, is a postulate in the system. If you start with the assumption that faster-than-light is impossible and build a system around that, the system you build around that assumption will always prove that it's impossible -- until something else proves otherwise.

Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

#46

Post by biot »

rbanffy wrote: post #36
Ygg2 wrote: post #15

Earlier quoted context omitted.

Seeing how if we use our warp drives to 'colonize' space, other creatures would have far more to fear from us than we from them (think Independence day with roles reversed). If a space faring species encounters non-space faring species, the one with warp is probably (not necessary) in the better position. Even without the weapons, FTL drive implies a magnitudes greater technology than anything a non-FTL race would ha…

> a space faring species encounters non-space faring species Any non space faring species either lives on a very boring neighborhood (one where rocks never fall from the sky and other kinds mass-extinction events never happen) or is extinct and we may find their fossil remains.

As far as we know, dolphins, cockroaches, and platypuses are not space faring species. Whether their neighborhood is boring is a matter of opinion, of course.

Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

#47

Post by nlh »

nessus42 wrote: post #35

You can't have faster than light travel without violations of causality. And while the equations of General Relatively allow for universes where causality is routinely violated, the probability that we are in such a universe seems vanishingly small. E.g., just because you can violate causality does not mean that you can go back in time and kill your grandfather. If you were to try, something would stop you, as a univ…

I'm not the down-voter, but I think you were likely down-voted because this article/discussion is not about time travel. And your first statement is that "you can't have faster-than-light travel..." is precisely what this paper discusses -- that with certain loopholes in physics (and consistent with General Relativity), faster-than-light travel is at least theoretically possible.

Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

#48

Post by nessus42 »

geuis wrote: post #44
nessus42 wrote: post #35

You can't have faster than light travel without violations of causality. And while the equations of General Relatively allow for universes where causality is routinely violated, the probability that we are in such a universe seems vanishingly small. E.g., just because you can violate causality does not mean that you can go back in time and kill your grandfather. If you were to try, something would stop you, as a univ…

We aren't talking about time travel. So many people confuse the idea of FTL with time travel. General Relativity talks about frames of reference. Suppose you had a base on Mars and sent a radio signal to it from Earth. It would take between 4.3 to 21 minutes to reach Mars, depending on its distance from Earth at the time. If you simultaneously jumped in your 10x warp drive and set out, you would arrive at Mars in 25.…

You are not correct. If anything with information travels faster than the speed of light, then there are frames of reference in which that information arrived at the destination before it left the origin.

Furthermore, unless your FTL drive is limited in ways that would make it utterly useless, any FTL drive can be used to make "closed time-like loops", which would allow travelers to meet up with their own past selves.

Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

#49

Post by nessus42 »

nlh wrote: post #47
nessus42 wrote: post #35

You can't have faster than light travel without violations of causality. And while the equations of General Relatively allow for universes where causality is routinely violated, the probability that we are in such a universe seems vanishingly small. E.g., just because you can violate causality does not mean that you can go back in time and kill your grandfather. If you were to try, something would stop you, as a univ…

I'm not the down-voter, but I think you were likely down-voted because this article/discussion is not about time travel. And your first statement is that "you can't have faster-than-light travel..." is precisely what this paper discusses -- that with certain loopholes in physics (and consistent with General Relativity), faster-than-light travel is at least theoretically possible.

Faster-than-light travel allows you to travel backwards in time. This is an essential part of Special and General Relativity. Those who don't understand this and who are not ready to address its consequences, should refrain from speculating on what is and isn't possible.

Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

#50

Post by nessus42 »

stan_rogers wrote: post #45
nessus42 wrote: post #35

You can't have faster than light travel without violations of causality. And while the equations of General Relatively allow for universes where causality is routinely violated, the probability that we are in such a universe seems vanishingly small. E.g., just because you can violate causality does not mean that you can go back in time and kill your grandfather. If you were to try, something would stop you, as a univ…

Causality, though, is a postulate in the system. If you start with the assumption that faster-than-light is impossible and build a system around that, the system you build around that assumption will always prove that it's impossible -- until something else proves otherwise.

Causality it NOT a postulate of the system. General Relativity fully allows for universes in which causality does not hold. Such universes would either turn out to be either very strange, or actual use of FTL drives would have to be extremely rare.
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