[HN Gopher] Ultrahigh-energy photons up to 1.4 PeV from 12 g-ray...
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       Ultrahigh-energy photons up to 1.4 PeV from 12 g-ray Galactic
       sources (2021)
        
       Author : gone35
       Score  : 19 points
       Date   : 2022-02-13 20:12 UTC (2 hours ago)
        
 (HTM) web link (www.nature.com)
 (TXT) w3m dump (www.nature.com)
        
       | qwertyuiop_ wrote:
       | For laymen, can someone who is knowledge put this into
       | persepective ?
        
         | johndough wrote:
         | 1.4 PeV are about 0.224 millijoules or roughly an 8 billionth
         | of a phone charge, so not much really. However, the photons we
         | usually deal with are weaker by an unimaginable amount, but
         | also much more plentiful. For example, a 100 W light bulb emits
         | something in the order of 10^21 photons per second. If you had
         | a light bulb that emitted the same amount of photons with 1.4
         | PeV each, you'd have a device equivalent to one Tsar bomb (the
         | most powerful bomb ever detonated in the history of mankind)
         | _every second_.
        
           | adhesive_wombat wrote:
           | That's a big old phone battery: 8 billion times 0.2mJ is a
           | 120000mAh 3.7V battery.
           | 
           | But yes, it's in that ballpark and it's a loooot of energy to
           | pack into a proton.
        
           | contravariant wrote:
           | It's roughly the amount of kinetic energy in a single grain
           | of rice if you gently throw a handful of them. It's not much,
           | but it's not an inconceivably small amount of energy either.
           | 
           | Comparing it to a phone charge is less useful because
           | batteries store _a lot_ of energy (especially when converted
           | to kinetic energy).
        
             | amluto wrote:
             | I would say that 1.4 PeV is enough energy (by a large
             | margin) to be audible. If that photon interacted with
             | something near you and deposited any respectable fraction
             | of its energy as heat or kinetic energy on a macroscopic
             | scale, you would hear it!
        
         | eesmith wrote:
         | https://en.wikipedia.org/wiki/Oh-My-God_particle might help.
        
           | _Microft wrote:
           | There is another, imo even better, page on this particle:
           | 
           | https://www.fourmilab.ch/documents/OhMyGodParticle/
        
           | adhesive_wombat wrote:
           | At 320 EeV, the OMG particle is over 5 orders of magnitude
           | more than 1.4 PeV. It's a completely nuts amount if energy to
           | have in a single particle: about the same as a decently
           | moving baseball. From the particle's frame, it takes only a
           | day to go a billion light years.
        
             | ipdashc wrote:
             | > 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/, 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 wrote:
               | 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.
        
         | planck01 wrote:
         | Its 100 times as much energy per photon than we as humans are
         | able to accelerate particles in the cern large hadron collider
         | with everything we have. It is a stupendous amount of energy
         | per photon.
        
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       (page generated 2022-02-13 23:00 UTC)