2mo ago

If we eliminate all particles and energies from a supernova explosion EXCEPT the ultradense neutrino blast and one stood there nearby, can one get ripped to shreds by the blast of neutrinos alone?

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There's a what if for that!
https://what-if.xkcd.com/73/
Turns out you can get knocked over by a feather!
- Sounds like the answer is probably no, but you could get a lethal dose of radiation
- Here's a question to give you a sense of scale:
  Which of the following would be brighter, in terms of the amount of energy delivered to your retina:
  A supernova, seen from as far away as the Sun is from the Earth, or
  The detonation of a hydrogen bomb pressed against your eyeball?
  Applying the physicist rule of thumb suggests that the supernova is brighter. And indeed, it is ... by nine orders of magnitude.
  Well... I wasn't expecting to read something like this today. Nor indeed, tomorrow and yesterday!
  EDIT:
  Then there's this, pointing out unbelievable stuff along the way, effortlessly. You gotta love Randall Munro.
  Core collapse supernovae happen to giant stars, so if you observed a supernova from that distance, you'd probably be inside the outer layers of the star that created it.
- I ran the numbers extending this. It would be 500,000km, or 0.004AU to vaporise meat. This is well inside the star, possibly within the core itself (making the maths even less reliable).
Even if the other forms of energy and matter from the supernova explosion were removed, the ultradense burst of neutrinos alone would literally vaporize someone from the inside in close proximity. While neutrinos are most often harmless, this is one of the few times they can be lethal. In a core-collapse supernova, roughly 99% of the energy is released as a burst of neutrinos, totaling about 10^53 ergs over 10 seconds. So the neutrino flux from the supernova would be so insane that enough neutrinos would collide with the atoms in your body to deposit lethal amounts of energy. This ultimately leads to one being vaporized from the inside!
- This is countered by the fact that neutrinos almost never interact with normal matter.
  Based on the xkcd discussion posted, you would get a 4 severts dose (lethal radiation) at around 2.3AU. About the orbit of Mars. This is radiation damage however. You likely wouldn't feel it directly, let alone be vaporised. This is also already inside the star going supernova.
  To vaporise meat takes about 1500000j/kg. This would equate to 1,500,000 severts. Assuming a point emitter, this would be with 0.004AU, or about 500,000km away. This is likely well within the core of the star, so the maths likely breaks down before this point.
  
  This is countered by the fact that neutrinos almost never interact with normal matter.
  Follow-up question, then:
  When they do in this extreme supernova scenario, are they frying their meat via direct impact (whatever that means at those scales) with the nucleus, or via the Weak Force?
  Because none of that energy is going to be transferred electromagnetically, a very strange thing to think about.
- Not so neutral then

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