4 ms·

> about the same as a decently moving baseball I heard this, but it's hard to believe it's real (or, obviously, I'm misunderstanding it). What would happen if

> about the same as a decently moving baseball I heard this, but it's hard to believe it's real (or, obviously, I'm misunderstanding it). What would happen if one of these hit a person in space? Would it be the same sort of feeling as getting hit by a baseball? Earlier I wondered how this much energy didn't totally wreck the detector, but someone else posted this link https://www.fourmilab.ch/documents/OhMyGodParticle/ https://www.fourmilab.ch/documents/OhMyGodParticle/, which says "The Fly's Eye consists of an array of telescopes which stare into the night sky and record the blue flashes which result when very high energy cosmic rays slam into the atmosphere". So the protons don't actually hit the detector. That makes more sense.

adhesive_wombat 5y ago
It doesn't interact like a baseball, it just has the energy of one. If it does hit an atom, it produces a shower of other particles, most of which will have similarly huge energies and will probably go right through the rest of the detector and start their own showers in other matter. So you'll get a detector with a few atomic dislocations, and the rest of the energy would be distributed amongst a huge number of other interactions. It's actually similar to x-ray "hardening", where soft x-rays are filtered out by a metal shield, leaving only harder radiation. This is carefully calibrated to allow the radiation to penetrate to a certain depth, leaving shallower tissue unharmed. In a way, it could be better to be hit by an OMG particle than a less energetic particle, as the amount of energy that gets dumped into you is smaller: the vast, vast majority of it would be shotgunned deep into the ground under you, and only a very few molecules in you are actually affected.
- ipdashc 5y ago
  Aha! I see.
- chasd00 5y ago
  Correct me if I’m wrong but at a photon’s scale a human is mostly empty space.
  - adhesive_wombat 5y ago
    Eh, kind of. It depends on the photon. A human is not transparent to visible light: if they were, we'd all be see-through. But we are substantially transparent to gamma rays. The same goes for baryons like protons: proton beam therapy can reach deep into humans, but alpha radiation (which is 2 protons and 2 neutrons, so not much "bigger") will be stopped by the first layer of skin. From the an OMG particle's perspective, at that speed, due to Lorentz contraction factor of 300 billion, a human is only a few picometres across.
    - MayeulC 5y ago
      Can the interaction also be approximated using the wavelength? E=hc/λ -> λ=hc/E -> λ=1.239/(1.4e15)=8.9e-16 μm Vanishingly small, about 900 yoctometers, or seven orders of magnitude smaller than a proton. No wonder we appear like empty space for the first few cascading reactions. Now, could dark matter just be photons with absurdly high energy?
      - beecafe 5y ago
        No, because dark matter concentrates around mass, which requires it to be able to be at rest to normal matter.

adhesive_wombat 5y ago

It doesn't interact like a baseball, it just has the energy of one. If it does hit an atom, it produces a shower of other particles, most of which will have similarly huge energies and will probably go right through the rest of the detector and start their own showers in other matter. So you'll get a detector with a few atomic dislocations, and the rest of the energy would be distributed amongst a huge number of other interactions. It's actually similar to x-ray "hardening", where soft x-rays are filtered out by a metal shield, leaving only harder radiation. This is carefully calibrated to allow the radiation to penetrate to a certain depth, leaving shallower tissue unharmed. In a way, it could be better to be hit by an OMG particle than a less energetic particle, as the amount of energy that gets dumped into you is smaller: the vast, vast majority of it would be shotgunned deep into the ground under you, and only a very few molecules in you are actually affected.

ipdashc 5y ago
Aha! I see.
chasd00 5y ago
Correct me if I’m wrong but at a photon’s scale a human is mostly empty space.
- adhesive_wombat 5y ago
  Eh, kind of. It depends on the photon. A human is not transparent to visible light: if they were, we'd all be see-through. But we are substantially transparent to gamma rays. The same goes for baryons like protons: proton beam therapy can reach deep into humans, but alpha radiation (which is 2 protons and 2 neutrons, so not much "bigger") will be stopped by the first layer of skin. From the an OMG particle's perspective, at that speed, due to Lorentz contraction factor of 300 billion, a human is only a few picometres across.
  - MayeulC 5y ago
    Can the interaction also be approximated using the wavelength? E=hc/λ -> λ=hc/E -> λ=1.239/(1.4e15)=8.9e-16 μm Vanishingly small, about 900 yoctometers, or seven orders of magnitude smaller than a proton. No wonder we appear like empty space for the first few cascading reactions. Now, could dark matter just be photons with absurdly high energy?
    - beecafe 5y ago
      No, because dark matter concentrates around mass, which requires it to be able to be at rest to normal matter.