Somewhat similar to https://en.wikipedia.org/wiki/Ablative_armor, but I don’t think it actually works. You’d have to put actual masses and speeds into a calculation to be sure, but “spinning much faster than the bullet/shrapnel moves” seems problematic. At the very least, you have to figure out how to keep the inner sphere suspended so it doesn’t contact the outer sphere. You might be able to ignore that bit by just calculating this as a space-borne defense mechanism: drop the outer shield, spin a sphere around your ship/habitat. I think you’ll still find that you have to spin it so fast that it deforms or disintegrates even without attack, for conventional materials.
It’s the easy solution to many problems in mechanics—put it in space, where you don’t have to worry about gravity, air friction, etc. You already specified that your elephant is uniform and spherical, so those complexities are already taken care of.
Somewhat similar to https://en.wikipedia.org/wiki/Ablative_armor, but I don’t think it actually works. You’d have to put actual masses and speeds into a calculation to be sure, but “spinning much faster than the bullet/shrapnel moves” seems problematic. At the very least, you have to figure out how to keep the inner sphere suspended so it doesn’t contact the outer sphere. You might be able to ignore that bit by just calculating this as a space-borne defense mechanism: drop the outer shield, spin a sphere around your ship/habitat. I think you’ll still find that you have to spin it so fast that it deforms or disintegrates even without attack, for conventional materials.
Mmm, good point about space-based system, that’s probably a much better use case!
It’s the easy solution to many problems in mechanics—put it in space, where you don’t have to worry about gravity, air friction, etc. You already specified that your elephant is uniform and spherical, so those complexities are already taken care of.