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Ultrahigh-energy photons up to 1.4 PeV from 12 γ-ray Galactic sources (2021)

nature.com

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Re: Ultrahigh-energy photons up to 1.4 PeV from 12 γ-ray Galactic sources (2021)

#21

Post by teraflop »

adhesive_wombat wrote: post #9
johndough wrote: post #5

Earlier quoted context omitted.

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 on…

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.

Presumably the parent commenter meant "8 billionths", not "one 8-billionth".

Re: Ultrahigh-energy photons up to 1.4 PeV from 12 γ-ray Galactic sources (2021)

#23

Post by [deleted] »

johndough wrote: post #5
qwertyuiop_ wrote: post #2

For laymen, can someone who is knowledge put this into persepective ?

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 on…

[deleted]

Re: Ultrahigh-energy photons up to 1.4 PeV from 12 γ-ray Galactic sources (2021)

#24

Post by [deleted] »

teraflop wrote: post #21
adhesive_wombat wrote: post #9

Earlier quoted context omitted.

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.

Presumably the parent commenter meant "8 billionths", not "one 8-billionth".

[deleted]

Re: Ultrahigh-energy photons up to 1.4 PeV from 12 γ-ray Galactic sources (2021)

#25

Post by ianai »

_Microft wrote: post #6
eesmith wrote: post #4

Earlier quoted context omitted.

https://en.wikipedia.org/wiki/Oh-My-God_particle might help.

There is another, imo even better, page on this particle: https://www.fourmilab.ch/documents/OhMyGodParticle/

Wonder if anyones re-looked at that origin path of the OMG particle in more recent times.

Re: Ultrahigh-energy photons up to 1.4 PeV from 12 γ-ray Galactic sources (2021)

#26

Post by raverbashing »

contravariant wrote: post #8
johndough wrote: post #5

Earlier quoted context omitted.

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 on…

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).

Yeah. Wolfram Alpha compares it to (a fraction of - something like 20%) the energy of pushing a key on a keyboard.

For one photon to have enough energy to push a rice grain is just crazy.

Makes me wonder which physical process created it. Even the hydrogen fusion photon is not that energetic.

Re: Ultrahigh-energy photons up to 1.4 PeV from 12 γ-ray Galactic sources (2021)

#27

Post by [deleted] »

xattt wrote: post #19
belter wrote: post #13

One of the coolest and easiest Physics home experiments, is to build your own cloud chamber, and use it as a particle detector. https://www.snolab.ca/outreach/resources-for-students-educat... "Build a particle detector": https://www.snolab.ca/wp-content/uploads/2021/11/Build-a-par... https://youtu.be/xky3f1aSkB8 "Cosmic Rays and the Cloud Chamber": https://crater.unh.edu/pdfs/CosmicRayBook.pdf

About 20 years ago, I was on trans-oceanic flight. Coffee was served at some point in the flight, and I am convinced the steam coming off the beverage, along with the higher altitude created a cloud chamber in front of me. While the coffee cooled, there were very distinct cosmic ray patterns within the steam that I cannot come up with any other explanation for.

[deleted]

Re: Ultrahigh-energy photons up to 1.4 PeV from 12 γ-ray Galactic sources (2021)

#28

Post by pmayrgundter »

xattt wrote: post #19
belter wrote: post #13

One of the coolest and easiest Physics home experiments, is to build your own cloud chamber, and use it as a particle detector. https://www.snolab.ca/outreach/resources-for-students-educat... "Build a particle detector": https://www.snolab.ca/wp-content/uploads/2021/11/Build-a-par... https://youtu.be/xky3f1aSkB8 "Cosmic Rays and the Cloud Chamber": https://crater.unh.edu/pdfs/CosmicRayBook.pdf

About 20 years ago, I was on trans-oceanic flight. Coffee was served at some point in the flight, and I am convinced the steam coming off the beverage, along with the higher altitude created a cloud chamber in front of me. While the coffee cooled, there were very distinct cosmic ray patterns within the steam that I cannot come up with any other explanation for.

Thanks for saying this. I've seen the same and wouldn't have thought of this explanation

Re: Ultrahigh-energy photons up to 1.4 PeV from 12 γ-ray Galactic sources (2021)

#29

Post by pmayrgundter »

teraflop wrote: post #20
qwertyuiop_ wrote: post #2

For laymen, can someone who is knowledge put this into persepective ?

Here's another way to put this into perspective: Photons carry momentum, although it's too small to be perceptible under ordinary circumstances. If a typical photon of sunlight hits an oxygen molecule in the Earth's atmosphere, and deposits all its momentum, it's enough to give that molecule a "kick" of a few centimeters per second. In contrast, a single one of these cosmic ray photons carries enough momentum (if it…

Imagining a cartoon image of it flying through the air yelling "Wheeeeee!" :)

Re: Ultrahigh-energy photons up to 1.4 PeV from 12 γ-ray Galactic sources (2021)

#30

Post by adhesive_wombat »

chasd00 wrote: post #17
adhesive_wombat wrote: post #11

Earlier quoted context omitted.

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 othe…

Correct me if I’m wrong but at a photon’s scale a human is mostly empty space.

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.

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