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Positive Energy Warp Drive from Hidden Geometric Structures

arxiv.org

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Re: Positive Energy Warp Drive from Hidden Geometric Structures

#11

Post by XorNot »

gary_0 wrote: post #9

What do the authors of these warp drive papers think will happen causality-wise when the proposed vehicle effectively moves faster than c? You can't do that without doing nasty things to your light cone[0] and effectively traveling into your own past. Is a prerequisite of entertaining the idea of a warp drive that we disregard causality? As far as I know, there aren't any plausible loopholes in General Relativity tha…

Well for one thing, a speed-of-light limited warp drive would still be effectively a reaction-less drive we could use for travel in the solar system.

But a decent way to beat Einstein would be find and implement an actual FTL engine: after all, if you can do it then obviously the theory isn't correct (alternately: the universe possible does not care about causality as much as we do in our little bubble of perception).

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#12

Post by sigmoid10 »

senectus1 wrote: post #3

I honestly thought this article was going to lead to something written by Charlse Stross. I mean with lines like "A geometrical interpretation of the Eulerian energy is found, shedding new light on superluminal solitons generated by realistic energy distributions" I'm still not sure it wasn't...

It might sound like gibberish to non-physicists, but it actually isn't. Eulerian energy is just the energy of something as observed by an eulerian observer, i.e. a normal observer traveling through spacetime (below the speed of light ofc). Solitons are just wave packets that keep their shape as they travel. None of the ideas presented here is new, not even the fact that these warp drives might work without negative energy. It's just a study of some more contrived geometries.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#13

Post by gary_0 »

XorNot wrote: post #11
gary_0 wrote: post #9

What do the authors of these warp drive papers think will happen causality-wise when the proposed vehicle effectively moves faster than c? You can't do that without doing nasty things to your light cone[0] and effectively traveling into your own past. Is a prerequisite of entertaining the idea of a warp drive that we disregard causality? As far as I know, there aren't any plausible loopholes in General Relativity tha…

Well for one thing, a speed-of-light limited warp drive would still be effectively a reaction-less drive we could use for travel in the solar system. But a decent way to beat Einstein would be find and implement an actual FTL engine: after all, if you can do it then obviously the theory isn't correct (alternately: the universe possible does not care about causality as much as we do in our little bubble of perception)…

> would still be effectively a reaction-less drive

True, but if the energy requirements for warp drives continue to be measured in Jupiters, reaction-mass is the least of your worries.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#14

Post by ctoth »

gary_0 wrote: post #9

What do the authors of these warp drive papers think will happen causality-wise when the proposed vehicle effectively moves faster than c? You can't do that without doing nasty things to your light cone[0] and effectively traveling into your own past. Is a prerequisite of entertaining the idea of a warp drive that we disregard causality? As far as I know, there aren't any plausible loopholes in General Relativity tha…

I believe the answer to this is [0], and the answer to that is [1]. I'm rather over my head here, and would love some analysis from people who know what the heck they're talking about.

[0]: https://arxiv.org/abs/2105.03079

[1]: https://eriklentzphd.blogspot.com/2021/05/response-to-new-pa...

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#15

Post by sigmoid10 »

gary_0 wrote: post #9

What do the authors of these warp drive papers think will happen causality-wise when the proposed vehicle effectively moves faster than c? You can't do that without doing nasty things to your light cone[0] and effectively traveling into your own past. Is a prerequisite of entertaining the idea of a warp drive that we disregard causality? As far as I know, there aren't any plausible loopholes in General Relativity tha…

General relativity actually tells us nothing about whether causality is absolute. You can easily make up spacetime configurations that violate causality and still conform to general relativity. It's just that most people believe that causality should be protected, because... well it would be really weird if it wasn't. But it's just a conjecture and not like a theorem or anything.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#16

Post by TheDudeMan »

gary_0 wrote: post #9

What do the authors of these warp drive papers think will happen causality-wise when the proposed vehicle effectively moves faster than c? You can't do that without doing nasty things to your light cone[0] and effectively traveling into your own past. Is a prerequisite of entertaining the idea of a warp drive that we disregard causality? As far as I know, there aren't any plausible loopholes in General Relativity tha…

"effectively traveling into your own past"

Can you explain how traveling faster than light leads to that? Perhaps you meant "observing your own past?"

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#17

Post by incompatible »

TheDudeMan wrote: post #16
gary_0 wrote: post #9

What do the authors of these warp drive papers think will happen causality-wise when the proposed vehicle effectively moves faster than c? You can't do that without doing nasty things to your light cone[0] and effectively traveling into your own past. Is a prerequisite of entertaining the idea of a warp drive that we disregard causality? As far as I know, there aren't any plausible loopholes in General Relativity tha…

"effectively traveling into your own past" Can you explain how traveling faster than light leads to that? Perhaps you meant "observing your own past?"

I'd guess there would be frames of reference (with relative high-speed motion) in which you'd appear at the destination before you've left the origin. The laws of physics are supposed to hold regardless of which frame of reference you use.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#18

Post by gfodor »

xelxebar wrote: post #8

"Warp drives in Einstein's general theory of relativity provide a unique mechanism for manned interstellar travel. It is well-known that the classical superluminal soliton[0] spacetimes require negative energy densities[1], likely sourced by quantum processes of the uncertainty principle. It has even been claimed by few that negative energy densities are a requirement of superluminal motion. However, recent studies s…

As a non physicist, the first question sounded like yes there is an ability to adjust speed if you can adjust the energy density distribution. I didn’t see an answer on the second beyond that the energy density required at the center is zero which leaves hope for a place to put a vehicle there at least, your question of flat space aside.

Curious if I read this right tho.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#19

Post by gfodor »

There is the threshold where these theories rule in human plausible warp drives, and then there is the weaker threshold where these theories rule in that they should be taken as serious explanations for the alleged “advanced technology” demonstrated by UAPs. I wonder what we ought to expect to see from such a device as an observer if the geometric formulation here is correct, even if we can’t explain the energy management problems. It sure would be nice if this research adds tools to the scientific community to start forming decent falsifiable hypotheses within the scope of an assumption of a given incident being such a tech demo.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#20

Post by javajosh »

incompatible wrote: post #17
TheDudeMan wrote: post #16

Earlier quoted context omitted.

"effectively traveling into your own past" Can you explain how traveling faster than light leads to that? Perhaps you meant "observing your own past?"

I'd guess there would be frames of reference (with relative high-speed motion) in which you'd appear at the destination before you've left the origin. The laws of physics are supposed to hold regardless of which frame of reference you use.

SR is 2 assertions, really: first, that the laws of physics are invariant in all reference frames, and second (and far stranger), that the speed of light is invariant in all reference frames. It's that second rule that must be violated for FTL to work - FTL implies a reference frame in which light can, at the very least, switch directions! That is, light from behind you looks like it's coming from the front (but still going c).
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