Results 1 to 21 of 21

Thread: 100% conversion of mass into energy

  1. #1
    Join Date
    Apr 2005
    Posts
    2,652

    100% conversion of mass into energy

    All I have to do to achieve this is compress mass into micro black holes.

    All the mass will then be radiated as Hawking radiation, thereby converting all the compressed mass into energy with 100% efficiency (not counting the energy needed to compress the matter into micro black holes).

    Is that correct?

  2. #2
    Join Date
    Mar 2004
    Posts
    19,362
    Well, there is the issue that Hawking radiation hasn’t been observed and it gets into an area of physics (the intersection of relativity theory and quantum physics) that isn’t fully established.

    Then, if valid, there would be the practical issues, like the energy needed to create the micro black hole, and what would come out of the black hole, which could be a variety of particles and gamma radiation. Much of it might not be terribly useful, like neutrinos, or too nasty to deal with.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  3. #3
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    38,039
    Quote Originally Posted by kzb View Post
    All I have to do to achieve this is compress mass into micro black holes.

    All the mass will then be radiated as Hawking radiation, thereby converting all the compressed mass into energy with 100% efficiency (not counting the energy needed to compress the matter into micro black holes).

    Is that correct?
    The matter that actually enters the MBH would, if Hawking radiation pans out, be converted to annihilating M/AM particles which would yield energy. But the compressed matter around the hole that has not yet entered would also be reacting to your pressure, producing various forms of radiation and heat. So you'd get less than 100% efficiency in practice.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  4. #4
    Join Date
    Apr 2005
    Posts
    2,652
    Quote Originally Posted by Noclevername View Post
    The matter that actually enters the MBH would, if Hawking radiation pans out, be converted to annihilating M/AM particles which would yield energy. But the compressed matter around the hole that has not yet entered would also be reacting to your pressure, producing various forms of radiation and heat. So you'd get less than 100% efficiency in practice.
    Yes I am quite prepared for it to be less than 100% in practice, nothing is ever 100% efficient.

    However, hydrogen fusion converts only 0.7% of mass into energy, so it is going to beat that.

    Antimatter/matter reaction gives off a large proportion of its energy as neutrinos, so that energy is lost.

    Also, there was fear that the LMC would produce black holes, so it must have some feasibility to it.

  5. #5
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    38,039
    Quote Originally Posted by kzb View Post
    Also, there was fear that the LMC would produce black holes, so it must have some feasibility to it.
    Subatomic black holes, that if HR is a thing would immediately evaporate. Building a useful sized black hole is well outside our capacity.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  6. #6
    Join Date
    Apr 2011
    Location
    Norfolk UK and some of me is in Northern France
    Posts
    9,282
    If we do make black holes here, would they not tunnel to the Earth’ centre? So we don’t know for sure if atom sized black holes get made accidentally?
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  7. #7
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    38,039
    Quote Originally Posted by profloater View Post
    If we do make black holes here, would they not tunnel to the Earth’ centre? So we don’t know for sure if atom sized black holes get made accidentally?
    Would they? We don't know much about how subatomic particles interact with gravity and other forces.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  8. #8
    Join Date
    Apr 2005
    Posts
    2,652
    Quote Originally Posted by Noclevername View Post
    Subatomic black holes, that if HR is a thing would immediately evaporate. Building a useful sized black hole is well outside our capacity.
    Immediate evaporation is exactly what is needed for a black hole rocket.

  9. #9
    Join Date
    Apr 2005
    Posts
    2,652
    Duplicate post

  10. #10
    Join Date
    Apr 2005
    Posts
    2,652
    Quote Originally Posted by profloater View Post
    If we do make black holes here, would they not tunnel to the Earth’ centre? So we don’t know for sure if atom sized black holes get made accidentally?
    They are meant to disappear in a shower of particles. They wouldn't live long enough to get far. None have been observed in the LHC though.

  11. #11
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    38,039
    Quote Originally Posted by kzb View Post
    Immediate evaporation is exactly what is needed for a black hole rocket.
    Gradual evaporation of a macro scale hole is what would be needed for a rocket. We are nowhere near that.

    ADDED: Tiny, undetectable BH that disappear as soon as they're created are of no practical use. Unless your rocket carries a miles-wide particle accelerator.
    Last edited by Noclevername; 2020-Oct-19 at 10:55 PM.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  12. #12
    Join Date
    Jun 2006
    Posts
    4,880

    Don't You Just Hate It When They Say "Whoops"

    Quote Originally Posted by kzb View Post
    All I have to do to achieve this is compress mass into micro black holes.

    All the mass will then be radiated as Hawking radiation, thereby converting all the compressed mass into energy with 100% efficiency (not counting the energy needed to compress the matter into micro black holes).

    Is that correct?
    Do us a favor. Don't do this at home.

  13. #13
    Join Date
    Apr 2005
    Posts
    2,652
    Quote Originally Posted by Noclevername View Post
    Gradual evaporation of a macro scale hole is what would be needed for a rocket. We are nowhere near that.

    ADDED: Tiny, undetectable BH that disappear as soon as they're created are of no practical use. Unless your rocket carries a miles-wide particle accelerator.
    I was thinking there could be some breakthrough technology which miniaturizes particle accelerators, or some easy way of making micro black holes is found.

    Really I was just asking the question. Having asked it I now realize this is not a new idea and indeed dates back to the 1970's. But I still don't think it gets any attention as an idea for space drives.

  14. #14
    Join Date
    Mar 2004
    Posts
    19,362
    Quote Originally Posted by kzb View Post
    Really I was just asking the question. Having asked it I now realize this is not a new idea and indeed dates back to the 1970's. But I still don't think it gets any attention as an idea for space drives.
    It has in science fiction and a bit in futurism/technological speculation. For instance, Charles Sheffield had a number of stories with ships using mini black holes. Arthur C. Clarke had it in Imperial Earth. Early stories didn’t assume Hawking radiation, though.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  15. #15
    Join Date
    Mar 2004
    Posts
    19,362
    Quote Originally Posted by kzb View Post
    Yes I am quite prepared for it to be less than 100% in practice, nothing is ever 100% efficient.

    However, hydrogen fusion converts only 0.7% of mass into energy, so it is going to beat that.

    Antimatter/matter reaction gives off a large proportion of its energy as neutrinos, so that energy is lost.
    So could a mini black hole. Matter/anti-matter is much more approachable with not insanely futuristic technology. One thought is to use a small amount of anti matter to make a fusion drive more feasible. Storing small amounts of anti-matter is possible.

    Also, there was fear that the LMC would produce black holes, so it must have some feasibility to it.
    That was considered an unlikely possibility based on rather speculative physics, which appears to not have been correct.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  16. #16
    Join Date
    Aug 2006
    Posts
    3,632
    I think there's something in this idea that's missing the point.

    100% energy conversion isn't in-and-of-itself the end-goal, as far as powering a spaceship goes.

    If it takes a billion years to extract that energy, then it's useless in a propulsion system.
    At the other end of the scale, if it evaporates before you can even get it into the spaceship, then it's useless in a propulsion system.

    The goal is to have access to an arbitrarily large amount of energy in an arbitrarily short amount of time. (Sort of like specific impulse of a fuel source, but I don't think that's the right term.)


    With that in-mind, I don't see any way, even in theory, you could use the radiation from any sized black hole to directly power a spaceship (thought that doesn't rule out indirect utilization).
    Last edited by DaveC426913; 2020-Oct-20 at 01:03 AM.

  17. #17
    Join Date
    Mar 2004
    Posts
    19,362
    Quote Originally Posted by profloater View Post
    If we do make black holes here, would they not tunnel to the Earth’ centre? So we don’t know for sure if atom sized black holes get made accidentally?
    Back in the LHC safety studies, scientists considered various possibilities like black holes and strangelets and if they could pose a risk. Basically, they considered that there are higher energy events happening constantly in nature, and looked at worlds, stars, even neutron stars (because they are very dense so would tend to stop almost anything interesting hitting them). They could find no evidence of any such being eaten by mini black holes or strangelets, so that was in large part their argument for why it couldn’t happen here.

    Incidentally, an atom sized black hole would be quite large given they were smashing subatomic particles.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  18. #18
    Join Date
    Mar 2004
    Posts
    19,362
    Quote Originally Posted by DaveC426913 View Post
    I think there's something in this idea that's missing the point.

    100% energy conversion isn't in-and-of-itself the end-goal, as far as powering a spaceship goes.

    If it takes a billion years to extract that energy, then it's useless in a propulsion system.
    At the other end of the scale, if it evaporates before you can even get it into the spaceship, then it's useless in a propulsion system.

    The goal is to have access to an arbitrarily large amount of energy in an arbitrarily short amount of time. (Sort of like specific impulse of a fuel source, but I don't think that's the right term.)

    With that in-mind, I don't see any way, even in theory, you could use the radiation from any sized black hole to power a spaceship.
    At least a couple methods have been proposed. If Hawking radiation exists, it would be irrelevant for even a black hole with the mass of a large asteroid, but a lower mass black hole could produce immense energy. In fact, the biggest problem with a small black hole in this scenario is that you can’t turn it off. You can either maintain its mass by feeding it (which can be tricky due to radiation pressure) or you can let it fully evaporate, which would be like being next to a very large nuclear explosion.

    In theory, it is possible to keep a charge on a black hole and manipulate it that way, but I’d suspect Hawking radiation would make that difficult (I would suspect it would tend towards a neutral charge). So you have a lot of emitted energy which could be directed, or used to heat a gas, and a possible way to control the black hole. I fully expect though that you wouldn’t do this unless you had a very large ship.

    Another method would be by using the Penrose process. Essentially you feed matter to a rotating black hole, the BH absorbs half of it, and the rest is ejected with a lot of excess velocity. This could work even with a classical black hole (no Hawking radiation). You could potentially use the black hole itself to accelerate a spacecraft if it is large enough by sending the ship in close orbit, and dropping part of the ship’s mass.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  19. #19
    Join Date
    Apr 2005
    Posts
    2,652
    Quote Originally Posted by DaveC426913 View Post
    I think there's something in this idea that's missing the point.

    100% energy conversion isn't in-and-of-itself the end-goal, as far as powering a spaceship goes.

    If it takes a billion years to extract that energy, then it's useless in a propulsion system.
    At the other end of the scale, if it evaporates before you can even get it into the spaceship, then it's useless in a propulsion system.

    The goal is to have access to an arbitrarily large amount of energy in an arbitrarily short amount of time. (Sort of like specific impulse of a fuel source, but I don't think that's the right term.)


    With that in-mind, I don't see any way, even in theory, you could use the radiation from any sized black hole to directly power a spaceship (thought that doesn't rule out indirect utilization).
    I am envisaging continuous on-board production of nano-black holes that evaporate in a tiny fraction of a microsecond. Not using one larger black hole, which seems to be the usual concept.

  20. #20
    Join Date
    Apr 2005
    Posts
    2,652
    Quote Originally Posted by Van Rijn View Post
    It has in science fiction and a bit in futurism/technological speculation. For instance, Charles Sheffield had a number of stories with ships using mini black holes. Arthur C. Clarke had it in Imperial Earth. Early stories didn’t assume Hawking radiation, though.
    Yes I've read Imperial Earth, and the space drive concept is quite different to "my" idea. As you say, it was not based on Hawking radiation, it used one re-usable black hole to accelerate propellant.

    BTW, I wonder if Hawking radiation would make Arthur C Clarke's space drive concept impossible?

  21. #21
    Join Date
    Apr 2005
    Posts
    2,652
    Quote Originally Posted by Van Rijn View Post
    So could a mini black hole. Matter/anti-matter is much more approachable with not insanely futuristic technology. One thought is to use a small amount of anti matter to make a fusion drive more feasible. Storing small amounts of anti-matter is possible.



    That was considered an unlikely possibility based on rather speculative physics, which appears to not have been correct.
    A large fraction of the antimatter/matter reaction is carried off by neutrinos, so is not usable. Hawking radiation is supposed to be photons. Although the expected showers of particles from BH's in the LHC confuses that picture.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •