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Old 2020-08-05, 23:57   #3939
ewmayer
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Quote:
Originally Posted by chalsall View Post
Hawking radiation is similar, but different.
?
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Old 2020-08-06, 00:10   #3940
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Quote:
Originally Posted by ewmayer View Post
?
A huge over-simplifaction (subject to correct by those who actually understand this stuff)...

Drop your thinking down to Quantum. Introduce virtual-particles. Run the simulations.

The speed C can't be reached by most particles (although they can get darn close, and others are stuck at that speed).

So they'll bleed off energy when required.

(And Black Holes evaporate.)
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Old 2020-08-06, 01:01   #3941
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Quote:
Originally Posted by chalsall View Post
A huge over-simplifaction (subject to correct by those who actually understand this stuff)...

Drop your thinking down to Quantum. Introduce virtual-particles. Run the simulations.

The speed C can't be reached by most particles (although they can get darn close, and others are stuck at that speed).

So they'll bleed off energy when required.

(And Black Holes evaporate.)
Re-?
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Old 2020-08-06, 01:13   #3942
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Quote:
Originally Posted by xilman View Post
Re-?
42. What was the question again?
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Old 2020-08-06, 03:33   #3943
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Lots of videos at that link (Beirut.) In some of them you see what I think must be chunks of concrete flying off the top of a building as the shock wave hits. Nearby highrise at the port appears to have no wall left on the facing side.

Grim stuff. Shades of Texas City. That was slightly less ammonium nitrate on board a ship in the harbor: 2300 tons NH4NO3 was the trigger for many secondary explosions, since there were oil storage tanks and refineries flattened, and another ship loaded with NH4NO3 which exploded a bit later.
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A mid-morning fire started on board the French-registered vessel SS Grandcamp (docked in the port) and detonated her cargo of about 2,300 tons (about 2,086 metric tons) of ammonium nitrate.[1] This started a chain reaction of fires and explosions in other ships and nearby oil-storage facilities, ultimately killing at least 581 people, including all but one member of the Texas City fire department.

Last fiddled with by kladner on 2020-08-06 at 03:39
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Old 2020-08-06, 10:00   #3944
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Quote:
Originally Posted by chalsall View Post
42. What was the question again?
What features of quantum electrodynamics leads you to the conclusion that Čerenkov radiation is similar to Hawking radiation?

Restricting attention solely to photons, Hawking radiation is emitted isotropically and with a thermal spectral distribution. Čerenkov is highly non-thermal and very anisotropic.

The Hawking process produces massive and mass-less particles. The Čerenkov process only mass-less ones.

Those are just a couple of examples which spring instantly to mind.
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Old 2020-08-06, 12:21   #3945
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Shockwave videos of all sorts: http://old.reddit.com/r/shockwaveporn
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Old 2020-08-06, 14:52   #3946
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Quote:
Originally Posted by xilman View Post
What features of quantum electrodynamics leads you to the conclusion that Čerenkov radiation is similar to Hawking radiation?
They both have the word "radiation" in them?

You are of course aware that I only have a meta understanding of the Quantum domain.

I can't hold a candle to folks like you (sincerely).
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Old 2020-08-06, 18:03   #3947
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With those many views and many structures, there will be much data for blast propagation and building techniques and materials. The shadow of the granary in the shockwave is interesting.
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Old 2020-08-06, 20:53   #3948
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I stole this from the megaporn link above. This is (supposedly) a picture of the warehouse with the door open, with the chemical culprit in full view.
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Old 2020-08-06, 22:10   #3949
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Quote:
Originally Posted by PhilF View Post
I stole this from the megaporn link above. This is (supposedly) a picture of the warehouse with the door open, with the chemical culprit in full view.
The Moon of Alabama article I linked to featured the same pic - and all those thousands of tons of this stuff were sitting there for over 6 *years*, just waiting for a suitable heat source, a welder's spark, a dropped still-lit cigarette remnant, what have you.
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