Let's be clear here. Alcubierre's original "warp drive" idea was for super-luminal speeds (faster than light) and required "exotic matter" (negative energy).
This new one is for sub-luminal speeds (slower than light). It does not require "exotic matter", but it's hardly a "warp drive"
Why not? From my understanding, to the ship’s occupants, they’d be travelling (EDIT: subjectively) super-luminally. In one lifetime they could go more than 100 ly.
I didn’t say it’s physically super-luminal. The undefined term is “warp drive.”
Given the ship’s occupants would subjectively travel super-luminally, it would seem to tick the boxes for warp. If it worked, you or I could travel to the other side of the galaxy. Hundreds of thousands of years would have elapsed outside the bubble. But we’d be alive.
I think it's an interesting point and you're not wrong to say it ticks at least one of boxes. It just doesn't match the concept that people have in mind, so an otherwise interesting discussion ends up rat-holing on semantics.
Is it? We don’t colloquially consider the Earth’s rotation or revolution.
This isn’t a Star Trek warp drive. But dismissing it as “hardly a warp drive” seems categorically wrong.
Wasn't this choice of reference frame the basis for that whole drama with Galileo, or am I misunderstanding?
It’s a “warp stasis” bubble or field: you’ve effectively suspended (or considerably slowed) the people inside to preserve them for the future — stasis.
I think you’re running into objections because while it is warp technology, it’s not a drive in that it’s not providing atypical propulsion (ie, Star Trek warp drives, Star Wars hyperspace drives, Babylon 5 subspace jump drives, etc).
You’re correct that we’re trying to define “warp drive”, but each of “warp” and “drive” are used independently — and your usage of “warp drive” doesn’t respect their independent usage. That you have a 1:1000 slowdown in perceived time to real time as your example suggests at some level you recognize this isn’t a drive.
I think warp stasis is a super cool technology all on its own, though.
AIUI in Star Trek, Cochrane's "space warp generator" and descendants are essentially the Alcubierre design: I don't seem to understand that the warp bubble provides any propulsion by itself (although grav waves could be surfed)
Instead AIUI actual movement is created by a secondary mechanism, which I'm unclear about from a cursory search. Maybe impulse engines? Or maybe those are inefficient/incompatible with warp and it's using a secondary system that comes as a (intentional by design) byproduct of nacelles, like a ramjet engine airplane essentially has two propulsion systems since requires forward speed so you gotta have regular engines.
It’s not really subjectively super-luminal either. The travellers could look behind them and see light catching up with them. A signal that left at the same time they left would be to their destination first. Relative to them, light always travels at light speed.
What is subjective is not light, but time.
If that’s your metric this isn’t the warp drive for you. That hardly means it isn’t a warp drive. The lifetime-lightyear travel boundary for possible experiences would be breached.
They require different kinds of energies. Specifically, the latter requires negative energy, something we have no evidence exists.
> being in a 'warp bubble' doesn't mean that bubble is traveling at super luminal speeds
Nobody claimed as much. The physically-possible warp bubble lets you slow down time. So a 100,000-year journey would feel, to the ship’s occupants (and its structure and computers, et cetera), like possibly months.
(You also get the capability to transport people and things forward in time without degradation. Or, I believe, to speed up time inside e.g. a production or computational environment.)
that... seems odd to me. without substantial changes in velocity - how does a warp bubble (that's sub-luminal - so relativistic velocities) alter the fabric of space-time so fantastically? It's not moving fast: so where does the time dilation come from?!
I think it’s from shifting momentum?? The paper is far beyond me [1]. But as I understood it, you’re directly modifying space-time with energy instead of using acceleration as a go-between.
https://github.com/NerdsWithAttitudes/WarpFactory
I'm impressed that they've removed the requirement for negative energy, but it's not quite ready to hand the drawings to your local machine shop to build one. It requires matter packed to an energy density on the order of 10^39 joules per cubic meter.
According to [1], oil has a (chemical) energy density of 4.5x10^10 joules per cubic meter, purified uranium produces 1.5x10^15 J/m^3 in a fission reactor, and that same uranium in pure mass-to-energy conversion produces on the order of 10^21 J/m^3. Uranium has a density of 19x10^3 kg/m^3, and the nucleus of an atom or neutron star has a density on the order of 4x10^17...if you can build the entire ship out of pure neutrons, you're still coming up short by a factor of ~100.
All that does suggest that it seems reasonable we'd be able to observe gravity waves from a long distance if a machine like that ever experienced a loss of compression.
[1]: https://drexel.edu/~/media/Files/greatworks/pdf_sum10/WK8_La...
Would you be getting into black hole territiry at that density?
Not really. Utah teapots are simulations of known objects [1]. Flight simulators of known phenomenon.
This is closer to Einstein or Schwarzschild’s theorising.
A simulation cannot be real. Results obtained from a real object are measurements.
If I’m simulating a bug, it doesn’t make the bug imaginary. The simulation is immaterial. (I wouldn’t quite call it imaginary. Computers don’t imagine.) But I am simulating a real thing. If, on the other hand, I simulate a bug the size of Paris, I am simulating something imaginary.
All simulations are immaterial. But the things they are simulating can be real or imagined.
Interesting that a difference of scale alone determined the nature of a thing! More interesting, perhaps, are the number of factors that aren't considered!
Would a simulation of a Peruvian ant on the Tibetan Plateau be real or imagined? What about a simulation of an ant after 20 years of climate change? How about an ant in space or experiencing the Big Bang?
On the other hand, is a simulation of a black hole real or imaginary? What about simulations of the history of the universe involving dark matter and dark energy?
I appreciate a sibling comment's (thanks marshray) suggestion that there exists a spectrum of theoreticalness. Theoreticity?
> the simulation in this paper is theoretical to a much larger degree than that of the teapot.
Are you really sure about that?
However, as an enjoyer of pedantic semantics, is the real Utah Teapot the physical pot or the model?
We routinely make detailed simulations of how such a physical teapot interacts with visible wavelengths of light, specifically for the purpose of comparing them with reality. From this we know that we do in fact have the ability to simulate this aspect of reality to a high degree of precision.
The ability to detect gravitational waves is just recently coming on-line, and we have no example of an actual warp drive to measure, so the simulation in this paper is theoretical to a much larger degree than that of the teapot.
Or you may have heard as it as all models are wrong
https://knowyourmeme.com/memes/skull-cow-isnt-real-it-cant-h...
Doesn’t this describe the lead up to any theoretical breakthrough?
Gravitational waves themselves were "imaginary" for a century or more (depending on who you credit) until they were directly measured in 2015.