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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

#51

Post by smallblacksun »

rickmode wrote: post #34
ChuckMcM wrote: post #12

Earlier quoted context omitted.

Well if you read the paper the effective speed is 10c, not .1c. They postulate 'boosting' the effective speed by contorting space-time around the craft, see this quote in the paper: "assume the spacecraft heads out towards Alpha Centauri and has a conventional propulsion system capable of reaching 0.1c. The spacecraft initiates a boost field with a value of 100 which acts on the initial velocity resulting in an appar…

So if I understand right, the warping does not affect the "internal" speed of the spaceship in relation of the universe outside of the warp bubble. Maybe someone much better with maths and physics can answer this: will the 0.1c speed have a noticable relativistic age-slowing effect for the travelers compared to their Earth-bound friends?

The time dilation effects don't become large enough to have significant affects on aging until speeds significantly higher than .1C. For example, to age at 1/2 normal rate, you would need to be going ~0.86C. This site has a calculator to play with: http://www.1728.org/reltivty.htm?b0=0.1

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

#52

Post by ChuckMcM »

rickmode wrote: post #34
ChuckMcM wrote: post #12

Earlier quoted context omitted.

Well if you read the paper the effective speed is 10c, not .1c. They postulate 'boosting' the effective speed by contorting space-time around the craft, see this quote in the paper: "assume the spacecraft heads out towards Alpha Centauri and has a conventional propulsion system capable of reaching 0.1c. The spacecraft initiates a boost field with a value of 100 which acts on the initial velocity resulting in an appar…

So if I understand right, the warping does not affect the "internal" speed of the spaceship in relation of the universe outside of the warp bubble. Maybe someone much better with maths and physics can answer this: will the 0.1c speed have a noticable relativistic age-slowing effect for the travelers compared to their Earth-bound friends?

1.005 seconds vs the observer at rest [1] So 157 days on the ship (.43 years) would be 158 days back at home.

[1] http://www.wolframalpha.com/input/?i=time+dialation+at+.1c

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

#53

Post by olalonde »

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…

This is a fun intellectual exercise but I think it would be fair to dismiss it as a "Maserati problem" for now. http://www.quora.com/Startups/Whats-a-Maserati-Problem

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

#55

Post by dhughes »

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.

I think the "faster than light" part wording seems a bit off since from what I gather the point is not to go fast to get to a location but to get there through warped space-time.

I imagine a 100 km long and 1km high brick wall, you're in the middle but want to get to the other side of the wall.

Option #1 is to travel as fast as you can 50km to one end and then 50km back to the spot on the other side.

Option #2 tunnel through the wall.

Option #1 is fast but the option #2 is faster although you didn't exceed the speed of option #1.

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

#56

Post by Evbn »

nessus42 wrote: post #49
nlh wrote: post #47

Earlier quoted context omitted.

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.

Is FTL the same as warping space? what happens in a (reduced dimensions for intuitiveness) scenario where a universe is like a line segment, and gets bent into crossing itself, allowing jumps from one point to another? Then there is a long way and a short way to send a message, kind of like travelling through vacuum is faster than traveling through water.

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

#57

Post by rootbear »

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 glad you brought this up. I got into this same argument on a Star Trek fan site and my opinions on the feasibility of FTL travel were not popular with that crowd. I would like to know what Alcubierre himself thinks about the causality issue. You simply can't wish it away.

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

#58

Post by lukevdp »

jerf wrote: post #21
randallsquared wrote: post #3

Earlier quoted context omitted.

Well, the Casimir effect generates a tiny amount of negative energy, does it not? Maybe that's how they think they can test it in the lab.

There are places in physics where "negative mass" can briefly appear, but as I understand it, the quantity of such negative mass times the duration of the negative mass is a constant... and a very, very small constant to boot. It's a balancing term in QM interactions, not something you're ever going to hold in your hands. As I like to say, assume one impossibility in physics, and it's not surprising that you get othe…

I agree entirely. The journalist in this article is giving the impression that this idea is more widely accepted than it actually is. It paints a picture of scientists agreeing on this when in reality it's a person or small group of people saying this.

At the same time, this kind of research is cool, and is an important part of science. It's just misrepresented by publications.

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

#59

Post by enraged_camel »

nessus42 wrote: post #48
geuis wrote: post #44

Earlier quoted context omitted.

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…

>>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.

No. If you send a radio signal to Mars, and then warp to Mars to find yourself there 0.1 seconds later, you are still 0.1 seconds after the moment on which you sent the signal from the point of origin. You are traveling faster than light, in the sense that you are traveling at [Earth-Mars Distance]/[0.1 sec] speed, but you are not actually traveling backwards in time to a point where you have not sent the signal yet.

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