5 ms·

They're simulating imaginary things?

mr_mitm 2y ago
They do that all the time.
throwaway48540 2y ago
The latest research in this field says it's physically (not just mathematically) possible - negative energy is no longer a requirement.
- vlovich123 2y ago
  Do you have any pointers?
  - throwaway48540 2y ago
    https://www.space.com/warp-drive-possibilities-positive-energy https://www.space.com/warp-drive-possibilities-positive-ener...
    - LeifCarrotson 2y ago
      https://arxiv.org/pdf/2405.02709 https://arxiv.org/pdf/2405.02709 https://github.com/NerdsWithAttitudes/WarpFactory 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_Layton_EnergyDensities.ashx https://drexel.edu/~/media/Files/greatworks/pdf_sum10/WK8_La...
      - adamnew123456 2y ago
        > 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 Would you be getting into black hole territiry at that density?
        deleted 2y ago
        [deleted]
- acchow 2y ago
  > not just mathematically 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"
  - JumpCrisscross 2y ago
    > 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.
    - mr_mitm 2y ago
      That doesn't match any definition of super-luminal that I have ever seen. Super-luminal means faster than light, period.
      - JumpCrisscross 2y ago
        > doesn't match any definition of super-luminal that I have ever seen 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.
        marshray 2y ago
        Typically we think of "speed" as observed from outside the moving [object], but I guess "typically" it doesn't matter. 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.
        2y ago
knappe 2y ago
You could have said that about the Nice model until we found it explained a lot of the early solar system formation and unified a lot of disparate working theories. https://en.m.wikipedia.org/wiki/Nice_model https://en.m.wikipedia.org/wiki/Nice_model
rbanffy 2y ago
They are imaginary just until their first detection.
JumpCrisscross 2y ago
> simulating imaginary things? Doesn’t this describe the lead up to any theoretical breakthrough?
itishappy 2y ago
By definition. That's what simulation means. ;)
- JumpCrisscross 2y ago
  > That's what simulation means Not really. Utah teapots are simulations of known objects [1]. Flight simulators of known phenomenon. This is closer to Einstein or Schwarzschild’s theorising. [1] https://en.m.wikipedia.org/wiki/Utah_teapot https://en.m.wikipedia.org/wiki/Utah_teapot
  - itishappy 2y ago
    Utah teapot is not real (it cannot hurt you). Despite being based on actual physical things, no Utah teapot will ever hold tea. A simulation cannot be real. Results obtained from a real object are measurements.
    - JumpCrisscross 2y ago
      The simulation is an imaginary thing. It is simulating something that is not imaginary. 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.
      - itishappy 2y ago
        I understand, completely agree, and plan to continue digging myself into this pedantic hole anyway thank you very much. 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.
colechristensen 2y ago
This is how a lot of science works. You guess that something exists and works a certain way, you build a model, then you see what measurable things that model predicts. Gravitational waves themselves were "imaginary" for a century or more (depending on who you credit) until they were directly measured in 2015.
exe34 2y ago
isn't that like 99% of modern mathematics?

They do that all the time.

The latest research in this field says it's physically (not just mathematically) possible - negative energy is no longer a requirement.

vlovich123 2y ago
Do you have any pointers?
- throwaway48540 2y ago
  https://www.space.com/warp-drive-possibilities-positive-energy https://www.space.com/warp-drive-possibilities-positive-ener...
  - LeifCarrotson 2y ago
    https://arxiv.org/pdf/2405.02709 https://arxiv.org/pdf/2405.02709 https://github.com/NerdsWithAttitudes/WarpFactory 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_Layton_EnergyDensities.ashx https://drexel.edu/~/media/Files/greatworks/pdf_sum10/WK8_La...
    - adamnew123456 2y ago
      > 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 Would you be getting into black hole territiry at that density?
      - deleted 2y ago
        [deleted]
acchow 2y ago
> not just mathematically 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"
- JumpCrisscross 2y ago
  > 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.
  - mr_mitm 2y ago
    That doesn't match any definition of super-luminal that I have ever seen. Super-luminal means faster than light, period.
    - JumpCrisscross 2y ago
      > doesn't match any definition of super-luminal that I have ever seen 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.
      - marshray 2y ago
        Typically we think of "speed" as observed from outside the moving [object], but I guess "typically" it doesn't matter. 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.
        2y ago

knappe 2y ago

You could have said that about the Nice model until we found it explained a lot of the early solar system formation and unified a lot of disparate working theories. https://en.m.wikipedia.org/wiki/Nice_model https://en.m.wikipedia.org/wiki/Nice_model

rbanffy 2y ago

They are imaginary just until their first detection.

JumpCrisscross 2y ago

> simulating imaginary things? Doesn’t this describe the lead up to any theoretical breakthrough?

itishappy 2y ago

By definition. That's what simulation means. ;)

JumpCrisscross 2y ago
> That's what simulation means Not really. Utah teapots are simulations of known objects [1]. Flight simulators of known phenomenon. This is closer to Einstein or Schwarzschild’s theorising. [1] https://en.m.wikipedia.org/wiki/Utah_teapot https://en.m.wikipedia.org/wiki/Utah_teapot
- itishappy 2y ago
  Utah teapot is not real (it cannot hurt you). Despite being based on actual physical things, no Utah teapot will ever hold tea. A simulation cannot be real. Results obtained from a real object are measurements.
  - JumpCrisscross 2y ago
    The simulation is an imaginary thing. It is simulating something that is not imaginary. 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.
    - itishappy 2y ago
      I understand, completely agree, and plan to continue digging myself into this pedantic hole anyway thank you very much. 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.

colechristensen 2y ago

This is how a lot of science works. You guess that something exists and works a certain way, you build a model, then you see what measurable things that model predicts. Gravitational waves themselves were "imaginary" for a century or more (depending on who you credit) until they were directly measured in 2015.

exe34 2y ago

isn't that like 99% of modern mathematics?