Okay so i saw this on /b/ earlier. And now i can't really

https://en.wikipedia.org/wiki/Relativistic_kill_vehicle

how much a bullet weight?

You might as well ask "what speed would a single molecule of tungsten have to be travelling at in order to kill you?"

The earth is too big compared to a bullet. It wouldn't even be able to destroy a medium sized country even if the bullet was as close to c as you wanted

>>7648639
You're full of shit.
The gravitational energy holding the earth together is only 4E32 Joules.

If you have a bullet going fast enough, it will just vaporize the earth.

Depends on the caliber

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>>7648666
The issue everyone misses here is energy transfer. Some high powered bullets are less deadly because they pierce though a person taking most of there destructive energy with them.

Depending on matter formation rates a single insanely high energy photon might be enough to do it. Actually this raise the interesting question if that insanely high energy photon would form a cascade of new matter that would likely repel and spread over a wider area giving better energy transfer on target.

In which case a few atoms and photons would be more then enough to temporarily transmit the energy needed to destroy the planet. Plus spotting a small cluster of atoms moving that fast is basically impossible.

Questions like this are going to end up getting 299792457.999999... meters per second.

>>7648144
it is definitly not retarded. It's not even trivial.

>>7648800
I know nothing about multiplicative showers. But yeah its a question of energy transfer. For equal energies, smaller-faster things tend to lose energy transfer effiency over heavier-slower things. At some point, a medium even gets transparent to small things with very high energy. (a 4 keV proton does way more dmg to any solid surface than a 1 GeV proton, which just goes through a medium with barely any interacting).

That being said, I don't see how the earth could be transparent to something the size of a bullet...
(That being said 2.0, the bullet would not reach ground by desintegrating in the atmosphere. Doing what kind of dmg? Idk...)

>>7648806
Pretty much this.

It is impossible, OP.

Lets say you accelerate the bullet to some obscenely close value to c.

Bullet enters the atmosphere. It is going so fast, that the effective cross-section of various air molecules is reduced to almost zero. Lets say it skips the atmopshere and makes it to the ground, just to be sure there is some significant impact.

So here, you get basically a miniature nuclear explosion, except for one problem. Every time an atom of your bullet impacts with an earth atom, the energy is so high both atoms are simply torn apart into sub atomic particles. This means there will be almost no transfer of momentum on the macro scale, because the atoms just get zipped off at near light speed. All the momentum goes into the reaction products of the nuclear interaction.

Now these sub-atomic particles go ripping thru the earth at nearly light speed, and now there is really no stopping them. Their relative cross section is so small, the earth is basically transparent. Even the ones who do interact, its singular atomic interactions spread throughout the bulk of the earth.

Even if you took ALL the atoms in the bullet, and said every single one of them will strike another atom dead on and cause an atomic fission, its just not that much energy that is going to be captured by the earth.

Almost everything gets blown out into space on the other side, at somewhat less than c, spreading out further into the cosmos to be detected by ayy lmao's who wonder wtf these particles actually are.

And now you know where high energy cosmic rays come from.

>>7648939
The best you can do, is to ensure that all the bullets energy is transfered as heat and momentum into a rather small area, by lowering its kinetic energy.

You get a wimpy nuclear explosion, quite small, not even enough to level a city. Certainly not enough to destroy the earth.

>>7648940
Of course, that is a bullet, which has a mass measured in grams. If you instead increase the mass (as in number of atoms, not effective mass due to velocity), then you can use a moderate velocity to deliver a WHOLE shit load of kinetic energy to the atmosphere/surface of the entire planet, and that is why comet and asteroid strikes can be so deadly.

>>7648939

>It is going so fast, that the effective cross-section of various air molecules is reduced to almost zero.
what? no. Cross-section is not reduced by speed. I got very skeptical at this point. And then:

>So here, you get basically a miniature nuclear explosion, except for one problem. Every time an atom of your bullet impacts with an earth atom, the energy is so high both atoms are simply torn apart into sub atomic particles.
you have no idea what you are talking about

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>>7648939

>the energy is so high both atoms are simply torn apart into sub atomic particles

lol no

>>7648894
Well the earth is mostly transparent to high energy neutrinos, thankfully as the few that do hit create small but detectable nuclear reactions. But something the size of a bullet would most likely hit hard, even if it had a piercing effect with I doubt. I saw hyper sonic impact testing and some undergrads with too much time. Let just say I am very certain speed destroys stuff.

One of my insane weapon designs uses 2 hydrogen atoms, 1 helium atom and a few photons carrying way too much energy. When these things interact under a set of specific conditions the energy can transmute into more hydrogen atoms with a lot of energy. The idea is the shot is fired with a calculated decay till the conditions are met. At which point you get a odd type of nuclear explosion where a mass of highly energized hydrogen suddenly starts to appear. This cloud spreads following a typical cone shape maximizing the area of effect. And well you can imagine the damage of an expanding cloud of high energy hydrogen moving near the speed of light can do once it hit the upper atmosphere. Not as much energy as a more typical large mass relativistic kill weapon at first glance, but the sudden compression would trigger a lot more secondary nuclear reaction in any lighter element based atmosphere planet. Want to see what happens when about 5% of the earth atmosphere suddenly under goes nuclear fusion? It makes the weapon harder to detect and uses less energy as the secondary nuclear reactions boost it. Bonus points if the atmospheric displacement triggers a slow decaying orbit into the local star.

This is why I am not allowed to design any new weapons. It is not enough to nuke a planet from orbit when do that, and nuke it inside an active star.

>>7648982
>>7649005
yeah. how the fuck do you think it works at CERN? They shoot millions of high energy, relativistic ions at blocks of lead, and you dont get a fucking "big explosion" you get a fucking shower of high energy particles. The higher the energy, the less chance there is even an interaction and the deeper you can probe into the sub-atomic physics.

>>7649015
>The higher the energy, the less chance there is even an interaction
Why do you think this?

>They shoot millions of high energy, relativistic ions at blocks of lead, and you dont get a fucking "big explosion" you get a fucking shower of high energy particles
Billions* Carbon* and you get a ton of heat produced. There is much more mass in a bullet than in all of the protons sent into the accelerator in a day (if not even more). I'm not sure why you think that if things go fast enough they will somehow magically not cause damage to the thing they impact.

You can dump an arbitrary amount of energy into a massive particle. You just need to ramp it up to relativistic speeds.

The amount of energy required to explode the earth can be calculated from https://en.wikipedia.org/wiki/Gravitational_binding_energy

>>7650093

I don't know much about relativistic QM, but I know some relativity and some QM.

When two objects are moving towards each other very fast, they appear thinner in the direction of movement. As you got faster and faster, the bullet and the earth would both appear way thinner to the other. As they get thinner and thinner, the chance of them not interacting goes up.