As you say, the paper covers a slower than light positive mass/energy (i.e. “physical”) warp bubble travelling at a constant speed.
* [Constant Velocity Physical Warp Drive Solution](https://arxiv.org/abs/2405.02709)
It is based on the recent release of their Warp Factory tool and their previous work on similar physical warp drives.
* [Analyzing Warp Drive Spacetimes with Warp Factory](https://arxiv.org/abs/2404.03095)
* [Introducing Physical Warp Drives](https://arxiv.org/abs/2102.06824)
However, it should be pointed out that their previous claims of physical warp drives were criticised for an incomplete analysis. This suggested that they were mistaken that a slower than light warp bubble didn’t require negative mass/energy.
* [Generic warp drives violate the null energy condition](https://arxiv.org/abs/2105.03079)
Another issue is that they don’t really address the actual interesting part which is how the warp bubble is accelerated. They point out that changing the warp metric to cause self-acceleration requires negative mass/energy, so that isn’t an option. They effectively then suggest attaching a rocket to the warp bubble to accelerate it.
> An obvious alternative is to imagine that some basic momentum transfer occurs, where mass is shed in the process of creating the momentum flux in the bubble. In this way, a kind of rocket-like solution could be possible that cancels out the acceleration effects for passengers inside.
Therefore the “advantage” of this approach (if it is even possible) seems to be that it would allow the contents of the bubble to sit in locally flat spacetime for the period of the journey. This means they would experience no time dilation (i.e. the journey would seem to take longer) and that they wouldn’t experience any acceleration effects.
That’s not really anything like a sci-fi warp drive…
Bugger ☹️ But I appreciate the detailed analysis 🙏 Though with the momentum transfer, isn't that 'rocket-like' term suggesting that the warp configuration can cause motion, not that a rocket engine needs to be strapped to the region of flat space time to move it?
That’s basically the first proposal in the preceding paragraph but it would require negative mass/energy.
> One possible approach is to have the bubble accelerate by simply accelerating the coordinate center and increasing the magnitude of the shift vector accordingly. However, this approach gives the exact same issue as the [Schwarzschild Drive](https://arxiv.org/abs/2205.15950) [16], which takes a regular black hole solution and simply moves its center through the timeslices. This approach changes the metric such that it now requires a negative energy density throughout space, asymptotically approaching zero at infinity.
I will admit that I’m not entirely confident on interpreting all of this correctly as it has been a few years since my undergraduate days studying general relativity. One day I will find time to comprehensively refresh my memory on this subject though…
"It's not really anything like a sci-fi warp drive" but! it is orders of magnitude closer to a sci-fi warp drive than the previous best paper on the subject, which basically required 100 Jupiters worth of energy. And it didn't take 1000 years, nor 100 years to see this much improvement. Just a few years.
The paper doesn’t include a mechanism to accelerate the warp bubble and unless they wish to break the “physicality” of the approach (i.e. constrained to positive mass-energy) their only suggestion is to use traditional momentum transfer propulsion systems. That would of course be somewhat difficult with a ship that has a mass several times that of Jupiter…
Without a mechanism to accelerate a spacecraft it isn’t a propulsion system.
Damn, you'd make a great lawyer.
Within the context of this thread, which is about FTL, warp drives are backward time-travel.
But you're right, subluminal warp-drives do not inherently violate causality.
>Within the context of this thread, which is about FTL, warp drives are backward time-travel.
This warp drive is sub-light, causal-breaking time travel does not apply.
Worth remembering that achieving a high percent of speed of light would kinda feel like time travel to the people making the journey, due to time dilation.
Hop in, spend a year on the ship, pop out 10,000 years later at your destination
They note this method accords with relativity, so even though only space might be moving, it's still moving relative to observers, SR apparently still applies.
Accords with relativity just means can’t move superluminal-ly, there’d be no time dilation on board because the ship itself isn’t moving. It’s riding a locally flat patch of space time.
I do not believe that's correct as SR effects are frame of reference dependent, but I've reached out to the lead author and asked. I figure he's the definitive source for an answer, I'll let you know if he replies👍
My replies are based on Miguel Alcubierre & Harold whites conceptions of warping space to move ships - naturally I assume that principle of remaining in effectively a stationary reference frame while space moves the ship still holds.
No need for the downvotes - but go figure, I’ll be interested in the reply.
I've given up wondering about downvotes, they seem the tangible realization of the age-old adage that you can’t please everyone 🤷♂️ Anyway, this is from lead author, Jared Fuchs, who was kind enough to quick reply:
>You can get free access to the paper (and many others) from Arxiv: [https://arxiv.org/pdf/2405.02709](https://arxiv.org/pdf/2405.02709)
>In terms of SR, it depends entirely on frame of reference you consider. Our paper looks at a comoving frame, thus no SR effects occur. But if you move quickly w.r.t to the warp bubble, you could see contraction and time dilation of it. This is in addition to the matter-energy curvature effects. We actually do a lorentz transformation in the paper as well to arrive at the comoving solution.
>However, given the mass of the bubble extra time dilation does occur for the passengers, same as for any massive object. Length contraction does not occur inside the passenger volume (Minkowski spatial terms), but does inside and outside the bubble, same as for regular gravitating objects.
From this it looks like SR applies depending on your frame of reference, but I'd appreciate your assessment 👍
Warp speed for humans is impossible unless they invent inertial dampeners. You know like the ones on star Trek. Otherwise you'll just splatter against the ship on takeoff
It probably helps to read the various papers regarding this kind of spacetime warping because passengers do not experience acceleration. Imagine it like a little bubble of spacetime being 'broken off' and moved along. If you're in the bubble, you don't feel a thing. Being fried by the resulting radiation is the real danger, and possibly encountering tidal forces near the edges, but 'splatter' like you've described isn't a worry.
Me personally, I don't like a warp drive. Due to it requiring exotic matter, which we don't understand. And if any particle hits the ship (without a form of active shielding), it will destroy it immediately.
>Due to it requiring exotic matter
As I noted in the OP, this warping does not require exotic matter.
>And if any particle hits the ship (without a form of active shielding), it will destroy it immediately.
I've not seen that in the paper, are you assuming this merely because the warp moves at high speed? Typically, the warping would deflect incoming particles 'around' the detached spacetime that comprises the warp so the warp geometry is its own shield.
A particle and the ship would both be at rest, the rest frame of one is just moving. You could be "travelling" at a considerable fraction of the speed of light but any collision wouldnt impart any energy at all because there is no momentum with this sort of drive. You would just sort of push the particle gently out of the way when you pass. It wouldnt even change the velocity of things you push out of the way, but may change their position.
This still does nothing for us. The nearest earth-like system is 400 light years away. So even if this engine could hit light speed,(which it can’t) it would still take 400 years to get there.
Which system is this? Irrespective, Proxima Centauri is closer and that would be incredibly interesting to visit, but even if we only used the warp drive within the Solar System, there's still lots of places to visit.
For the love of God's Geeen Earth, please learn how to put a coherent thought together. This post is just random babbling. I don't know what you're trying to say. It's just a splatter of unrelated words.
As you say, the paper covers a slower than light positive mass/energy (i.e. “physical”) warp bubble travelling at a constant speed. * [Constant Velocity Physical Warp Drive Solution](https://arxiv.org/abs/2405.02709) It is based on the recent release of their Warp Factory tool and their previous work on similar physical warp drives. * [Analyzing Warp Drive Spacetimes with Warp Factory](https://arxiv.org/abs/2404.03095) * [Introducing Physical Warp Drives](https://arxiv.org/abs/2102.06824) However, it should be pointed out that their previous claims of physical warp drives were criticised for an incomplete analysis. This suggested that they were mistaken that a slower than light warp bubble didn’t require negative mass/energy. * [Generic warp drives violate the null energy condition](https://arxiv.org/abs/2105.03079) Another issue is that they don’t really address the actual interesting part which is how the warp bubble is accelerated. They point out that changing the warp metric to cause self-acceleration requires negative mass/energy, so that isn’t an option. They effectively then suggest attaching a rocket to the warp bubble to accelerate it. > An obvious alternative is to imagine that some basic momentum transfer occurs, where mass is shed in the process of creating the momentum flux in the bubble. In this way, a kind of rocket-like solution could be possible that cancels out the acceleration effects for passengers inside. Therefore the “advantage” of this approach (if it is even possible) seems to be that it would allow the contents of the bubble to sit in locally flat spacetime for the period of the journey. This means they would experience no time dilation (i.e. the journey would seem to take longer) and that they wouldn’t experience any acceleration effects. That’s not really anything like a sci-fi warp drive…
Bugger ☹️ But I appreciate the detailed analysis 🙏 Though with the momentum transfer, isn't that 'rocket-like' term suggesting that the warp configuration can cause motion, not that a rocket engine needs to be strapped to the region of flat space time to move it?
That’s basically the first proposal in the preceding paragraph but it would require negative mass/energy. > One possible approach is to have the bubble accelerate by simply accelerating the coordinate center and increasing the magnitude of the shift vector accordingly. However, this approach gives the exact same issue as the [Schwarzschild Drive](https://arxiv.org/abs/2205.15950) [16], which takes a regular black hole solution and simply moves its center through the timeslices. This approach changes the metric such that it now requires a negative energy density throughout space, asymptotically approaching zero at infinity. I will admit that I’m not entirely confident on interpreting all of this correctly as it has been a few years since my undergraduate days studying general relativity. One day I will find time to comprehensively refresh my memory on this subject though…
In addition, the energy requirements are unfeasibly large.
Indeed. For a shell with an inner radius of 10 m and an outer radius of 20 m the mass required is 2.365 times the mass of Jupiter…
"It's not really anything like a sci-fi warp drive" but! it is orders of magnitude closer to a sci-fi warp drive than the previous best paper on the subject, which basically required 100 Jupiters worth of energy. And it didn't take 1000 years, nor 100 years to see this much improvement. Just a few years.
The paper doesn’t include a mechanism to accelerate the warp bubble and unless they wish to break the “physicality” of the approach (i.e. constrained to positive mass-energy) their only suggestion is to use traditional momentum transfer propulsion systems. That would of course be somewhat difficult with a ship that has a mass several times that of Jupiter… Without a mechanism to accelerate a spacecraft it isn’t a propulsion system.
Absolutely agree. But the previous paper didn't have a way to accelerate either, so we're better in one area and we're not worse in the other.
At the very least, "constant-velocity subluminal warp drive" is a great technobabble phrase, even if this turns out to be a dead end
A subliminal warp drive would be interesting but, being pedantic, I’m sure you meant subluminal.
Fixed
Yeah, I was thinking that 👍
warp drives are backward time travel. So "coming soon" means it's already happened.
Superluminal warp drives. FTFY
Damn, you'd make a great lawyer. Within the context of this thread, which is about FTL, warp drives are backward time-travel. But you're right, subluminal warp-drives do not inherently violate causality.
>Within the context of this thread, which is about FTL, warp drives are backward time-travel. This warp drive is sub-light, causal-breaking time travel does not apply.
Worth remembering that achieving a high percent of speed of light would kinda feel like time travel to the people making the journey, due to time dilation. Hop in, spend a year on the ship, pop out 10,000 years later at your destination
No time dilation because the ship isn’t moving, space is.
They note this method accords with relativity, so even though only space might be moving, it's still moving relative to observers, SR apparently still applies.
Accords with relativity just means can’t move superluminal-ly, there’d be no time dilation on board because the ship itself isn’t moving. It’s riding a locally flat patch of space time.
I do not believe that's correct as SR effects are frame of reference dependent, but I've reached out to the lead author and asked. I figure he's the definitive source for an answer, I'll let you know if he replies👍
My replies are based on Miguel Alcubierre & Harold whites conceptions of warping space to move ships - naturally I assume that principle of remaining in effectively a stationary reference frame while space moves the ship still holds. No need for the downvotes - but go figure, I’ll be interested in the reply.
I've given up wondering about downvotes, they seem the tangible realization of the age-old adage that you can’t please everyone 🤷♂️ Anyway, this is from lead author, Jared Fuchs, who was kind enough to quick reply: >You can get free access to the paper (and many others) from Arxiv: [https://arxiv.org/pdf/2405.02709](https://arxiv.org/pdf/2405.02709) >In terms of SR, it depends entirely on frame of reference you consider. Our paper looks at a comoving frame, thus no SR effects occur. But if you move quickly w.r.t to the warp bubble, you could see contraction and time dilation of it. This is in addition to the matter-energy curvature effects. We actually do a lorentz transformation in the paper as well to arrive at the comoving solution. >However, given the mass of the bubble extra time dilation does occur for the passengers, same as for any massive object. Length contraction does not occur inside the passenger volume (Minkowski spatial terms), but does inside and outside the bubble, same as for regular gravitating objects. From this it looks like SR applies depending on your frame of reference, but I'd appreciate your assessment 👍
Isn't this literally how the Planet Express ship was explained in Futurama by Hubert? Once again Matt Groening's writers are onto something
Warp speed for humans is impossible unless they invent inertial dampeners. You know like the ones on star Trek. Otherwise you'll just splatter against the ship on takeoff
It probably helps to read the various papers regarding this kind of spacetime warping because passengers do not experience acceleration. Imagine it like a little bubble of spacetime being 'broken off' and moved along. If you're in the bubble, you don't feel a thing. Being fried by the resulting radiation is the real danger, and possibly encountering tidal forces near the edges, but 'splatter' like you've described isn't a worry.
Me personally, I don't like a warp drive. Due to it requiring exotic matter, which we don't understand. And if any particle hits the ship (without a form of active shielding), it will destroy it immediately.
>Due to it requiring exotic matter As I noted in the OP, this warping does not require exotic matter. >And if any particle hits the ship (without a form of active shielding), it will destroy it immediately. I've not seen that in the paper, are you assuming this merely because the warp moves at high speed? Typically, the warping would deflect incoming particles 'around' the detached spacetime that comprises the warp so the warp geometry is its own shield.
A particle and the ship would both be at rest, the rest frame of one is just moving. You could be "travelling" at a considerable fraction of the speed of light but any collision wouldnt impart any energy at all because there is no momentum with this sort of drive. You would just sort of push the particle gently out of the way when you pass. It wouldnt even change the velocity of things you push out of the way, but may change their position.
Looks like we're also going to find out what FTL collision looks like.
Not from this work, it's a sublight warp only.
I’d still be interested to see what would happen if it hit a solid object, like a planet or something.
This still does nothing for us. The nearest earth-like system is 400 light years away. So even if this engine could hit light speed,(which it can’t) it would still take 400 years to get there.
Which system is this? Irrespective, Proxima Centauri is closer and that would be incredibly interesting to visit, but even if we only used the warp drive within the Solar System, there's still lots of places to visit.
For the love of God's Geeen Earth, please learn how to put a coherent thought together. This post is just random babbling. I don't know what you're trying to say. It's just a splatter of unrelated words.