Comments by "Jeff Huffman" (@tejing2001) on "Testing the US Military’s Worst Idea" video.

If you look into a far future interstellar context, though, kinetic weapons become truly scary. Relativistic kinetic missiles are just terrifying in damage potential. Planet-wide extinction-level events can be created by just a single one.
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@maxv9464 Nope, you have to vaporize them, and with enough lead time for the mass to spread out to the point that the kinetic energy density is not dangerous.
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@MattsAwesomeStuff The faster an RKM is going, the more time and distance is needed to accelerate it up to that speed, which gives you a decent amount of lead time as long as you're looking far enough away. Faster projectiles are also easier to detect at longer distances due to increased heating on the front surface from interstellar dust impacts. So practically, you do have quite a bit of advance warning if you are actively looking for them with enough imaging equipment and compute power. Isaac Arthur has some great videos exploring the practical limits of such things.
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