• Question: If anti-gravity was to be invented and used primarily everywhere, would this be the end of coal, oil gas and fuel?

    Asked by anon-258065 on 26 Jun 2020.
    • Photo: Richard Fielder

      Richard Fielder answered on 26 Jun 2020:

      Probably not. Even if we discovered some way of manipulating gravity, we would almost certainly need a power source for whatever technology allowed us to do it. Even if we invented a material that somehow repelled gravity (a popular idea in sci-fi), we’d still need power to move it around in order to be useful. We could likely reduce the amount of power needed for transportation, for the same reason maglev trains can go faster than normal ones because they don’t need to worry about friction as much, but there’s no way of moving things around without using some energy, and that always needs to come from somewhere.

    • Photo: James Smallcombe

      James Smallcombe answered on 26 Jun 2020:

      Anti-gravity would certainly be very useful, but with our current understanding of physics we couldn’t use it as a fuel source due to conservation of energy.
      With example of electromagnetic force, we know we can have positive or negative charges and attractive and repulsive forces, but we cant get free energy from these. Two like charges will push each other away and we can harness some energy from this, but we have to put energy in to bring the charges together in the first place.
      Going back to gravity, if we did discover some way of making anti-gravity, it would take at least as much energy as the gravitational potential energy involved, and probably a lot more.
      But it might be really useful for getting things into space without relying on rockets, and maybe it would change the transport industry. We are already moving towards levitating trains with current physics.

    • Photo: Christopher Erickson

      Christopher Erickson answered on 26 Jun 2020:

      I love this question! A good sign when I read a question is I think, well the answer is obvious. Yes … wait, no … of course it’s maybe. In short, your question made me think long enough to realize why your question has no answer.

      There’s a common complaint in science fiction that people invent antigravity (or artificial gravity) and they use it for standing on spaceships. You’ve mastered one of the fundamental forces of the universe, the force that tells you how cause links to effect and you can change the nature of that linkage through basic causes and effects, and you use it to stand on spaceships.

      If we invent antigravity, do we have the ability to create micro black holes and use those as energy sources? Of course, the energy to do that would have to come from somewhere, but might that energy come from the quantum vacuum itself? Does that even make sense, as it violates the second law of thermodynamics? The second law of thermodynamics is only true in the thermodynamic limit, is the quantum vacuum something where the assumptions of thermodynamics hold?

      The reason why your question is difficult to answer is because it is some sort of probabilistic version of ex falso quodlibet. If we assume a huge part of our current knowledge, which certainly makes it look like antigravity is either impossible or very hard, is broken, what does reality look like in that post-infinitesimal-observation landscape?

      We don’t know, and, if we did know, your question wouldn’t make sense.

      Cheers!

    • Photo: Susan Cartwright

      Susan Cartwright answered on 29 Jun 2020:

      I’m not sure you even could “invent” antigravity, any more than you can “invent” electricity. Gravity is a fundamental force of nature, and in our current best theory of gravity (Einstein’s general theory of relativity) it only has a one sign: there is no antigravity. (Dark energy acts as anitgravity in some cosmological contexts, but not in general.)

      One could imagine a scenario in which someone constructs a working theory of quantum gravity, and that working theory predicts antigravity. It still doesn’t follow that it would solve all our energy problems, because it is not clear that it would be easy to find or make. For example, antimatter definitely exists, and generating energy by matter-antimatter annihlation is VASTLY more efficient than any of our current methods. But antimatter is not common in nature, for reasons we do not yet understand (when we make particles in the lab, we make matter-antimatter pairs, but the universe seems to be essentially all matter), so we would have to make any antimatter we used, ad aking it would cost more energy than we’d get out of annihilating it (because of the second law of thermodynamics). Antigravity doesn’t seem to be common in the universe either, so this might turn out to be the same sort of thing: onlt some exotic form of matter produces antigravity, and making the exotic form of matter costs more energy than you get out. (Remember, this is all based on the assumption that in some beyond-general-relativity theory it has been shown that antugravity exists: at the moment, we’ve no reason to believe it does.)

      If antigravity were easy to make, I think we would already have seen evidence of its existence – so my guess is that either it does not exist or it is hard to make. In either case, I’m afraid it does not solve our energy problems.

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