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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

#61

Post by hyperpallium2 »

godelski wrote: post #50

Everyone always talks about FTL travel for spacecraft, but there's also an interesting perspective from weapons side (and this a reason to be a bit careful and think about some ethics as we move along). A FTL kinetic weapon would be devastating. If it comes with a collapsing warp bubble then there's basically a gamma ray "gun" that travels right in front of your mass that is traveling at tremendous speeds. You look a…

If we're talking surprising applications of FTL, what about reducing latencies within CPUs?

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#63

Post by dleslie »

nine_k wrote: post #38
sigmoid10 wrote: post #15

Earlier quoted context omitted.

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.

AFAICT, GR is symmetric in relation of the direction of time, as are most other important physical theories. What may add the arrow of time is the second law of thermodynamics: a statistical evolution of a system is not symmetric. I wonder now how a violation of causality could either circumvent of contradict the second law.

It's not creating new energy, right? It reads to me like causality violating configurations simply move energy around time as we'd move mass through space.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#64

Post by gopher_space »

AnimalMuppet wrote: post #40
sigmoid10 wrote: post #15

Earlier quoted context omitted.

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.

That conjecture is one of the two foundational principles of relativity - that the laws of physics are the same in all valid frames of reference. "Violating causality" means that in some valid frame of reference A, event X caused event Y, and in some other valid frame of reference B, event Y caused event X. The laws of physics cannot be the same in A and B for both of those to be true.

I'm watching two friends go through a nasty breakup that "violates causality" if you take both points of view into account, and am realizing that it's impossible to do any work with pop-sci physics because I'm relying on an extended metaphor to grasp the topic.

It's clear that your point of view matters in physics, but it's also clear that I have no idea what a "point of view" means in this context.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#65

Post by javajosh »

jlokier wrote: post #37
javajosh wrote: post #29

Earlier quoted context omitted.

No, it isn't. Light is unique in this way.

No it isn't. The speed of light in SR is not really about light. It's just a good way to explain things. You can calculate the speed of light from other physical, measurable constants without using light (the permittivity and permeability of free space). Those you can measure with inductors and capacitors. So because those measurable physical behaviours are invariant in all reference frames under SR, it follows that…

c is defined. https://physics.nist.gov/cgi-bin/cuu/Value?c

You don't have to measure c, or calculate it. The causal chain goes the other way - we assume c is invariant and define capacitance and inductance in terms of it (c, that is).

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#66

Post by randmeerkat »

stjohnswarts wrote: post #54
randmeerkat wrote: post #53

Earlier quoted context omitted.

Maybe, or what if it’s exactly what the DoD is saying? That there’s verified advanced UAPs beyond our current technological understanding.

I don't they said "there are uaps beyond..." , they said they couldn't explain all of them, that's all.

“UAP clearly pose a safety of flight issue and may pose a challenge to U.S. national security. Safety concerns primarily center on aviators contending with an increasingly cluttered air domain. UAP would also represent a national security challenge if they are foreign adversary collection platforms or provide evidence a potential adversary has developed either a breakthrough or disruptive technology.”

https://www.dni.gov/files/ODNI/documents/assessments/Prelima...

I think breakthrough or disruptive technology are the key words here. They may not have said “beyond” but pretty much said everything short of that.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#67

Post by gary_0 »

perihelions wrote: post #34
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…

"What do the authors of these warp drive papers think will happen causality-wise" According to §3.3, they aren't sure. If I parsed it correctly, they haven't mathematically resolved whether closed timelike curves are necessary, or precluded, or neither.

The last part of that section suggests (with a citation) that "horizon formations [may] prevent the configurations from transporting an inertial observer from the subluminal regime to the superluminal regime." So it's a distinct possibility that warp drives can't actually go FTL.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#68

Post by godelski »

cletus wrote: post #39

The lesson we should really take here is the power of wishful thinking. People dearly want to believe in FTL travel. Without it, the Universe just seems so vast, empty and distant. The truth is it is and it isn't. It's only really that on our current time scales. Not to be a broken record (there's some new variation on some old idea like every week it seems), but I'm firmly in the camp that believes FTL isn't possibl…

> The macro evidence in that if FTL were possible it makes it that much more unlikely that we haven't detected starfaring life.

I don't think this is a great argument. Even with FTL the galaxy (not universe) is huge. Let's just say you can go 2x (warp factor 1.25) it would still take more than 2 years to reach Alpha Centauri (our closest star, 4.37 lyr). Even at 8c (Warp 2) it would still take >6 months. At 100c it is 2 weeks. The energy to travel these different speeds presumably does not scale well and so the difference between 2c and 1000c is going to be different level of civilizations[0]. The Milky Way is 2 million light years in diameter. There's about 1000 stars within 50 light years. Here's a list of stars I think a lot of people miss how huge the galaxy is (let alone Universe). Nothing is accessible without FTL. FTL is _necessary_. That, or immortality, or generational ships. The problem is that these numbers are so incomprehensibly large that we think they are magnitudes smaller than they actually are.

However big you think the galaxy is, it is actually bigger.

[0] https://en.wikipedia.org/wiki/Kardashev_scale

[1] https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brow...

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#69

Post by R0b0t1 »

hyperpallium2 wrote: post #61
godelski wrote: post #50

Everyone always talks about FTL travel for spacecraft, but there's also an interesting perspective from weapons side (and this a reason to be a bit careful and think about some ethics as we move along). A FTL kinetic weapon would be devastating. If it comes with a collapsing warp bubble then there's basically a gamma ray "gun" that travels right in front of your mass that is traveling at tremendous speeds. You look a…

If we're talking surprising applications of FTL, what about reducing latencies within CPUs?

This is a good one. The limits on the mass needed to construct the system are quite large, but perhaps you can get a weaker effect much more easily.

Re: Positive Energy Warp Drive from Hidden Geometric Structures

#70

Post by godelski »

hyperpallium2 wrote: post #61
godelski wrote: post #50

Everyone always talks about FTL travel for spacecraft, but there's also an interesting perspective from weapons side (and this a reason to be a bit careful and think about some ethics as we move along). A FTL kinetic weapon would be devastating. If it comes with a collapsing warp bubble then there's basically a gamma ray "gun" that travels right in front of your mass that is traveling at tremendous speeds. You look a…

If we're talking surprising applications of FTL, what about reducing latencies within CPUs?

This would also be neat. And of course any information communication. While Ansibles[0] are typically used to verbally communicate with someone why not any information?

[0] https://en.wikipedia.org/wiki/Ansible

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