5 ms·

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

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