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The Sound So Loud That It Circled the Earth Four Times

nautil.us

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Re: The Sound So Loud That It Circled the Earth Four Times

#31

Post by pavel_lishin »

beloch wrote: post #23

To put this in context, the Krakatoa eruption released energy roughly equivalent to a 200 megaton bomb, which is roughly four times larger than the "Tsar Bomba", an H-Bomb which is the largest nuclear weapon detonated to date. The globe's average temperature fell 1.2 C after the eruption due to SO2 increasing the Earth's albedo. The Volcanic Explosivity Index (VEI) of the Krakatoa eruption was 6, and it's estimated t…

> People are strangely obsessed with the threat of asteroid impacts when what's beneath our feet presents a perhaps even greater danger, one which we know next to nothing about!

I'd wager we're much closer, technologically, to do something about asteroids, though. Not quite so much about eruptions.

Re: The Sound So Loud That It Circled the Earth Four Times

#32

Post by rspeer »

danielweber wrote: post #11

So the sound got harder to hear as you were farther away, but what if you were at the exact antipode on Earth? Would it have been audible at all?

Something that makes this extra intriguing: the exact antipode of Krakatoa seems to be in an inhabited area on the banks of the Rio Magdalena in Colombia.

I wonder if anyone was there at the time to notice a pressure wave coming from all directions.

Re: The Sound So Loud That It Circled the Earth Four Times

#33

Post by Anechoic »

SEJeff wrote: post #14
aatish wrote: post #3

Hey, I'm the author of the post (on twitter @aatishb). Thanks for voting it up. Would love to hear your thoughts and constructive feedback. Cheers. (PS the references linked to at the bottom of the post are packed with fascinating information about Krakatoa, for anyone who wants to dig deeper.)

One thing I'm surprised you didn't mention is infrasound[1], which is sound so low that it can potentially damage the human body. Some of the newer non-lethal weapons the US military use for crowd control include a directional infrasound "gun" that basically vibrates your inner organs fast enough to make everyone super nauseous. [1] http://en.wikipedia.org/wiki/Infrasound

Some of the newer non-lethal weapons the US military use for crowd control include a directional infrasound "gun" that basically vibrates your inner organs fast enough to make everyone super nauseous.

Do you have a cite for this? A "directional" outdoor infrasound weapon would be huge (10s of feet) and quick web search seems to indicate these types of weapon are at best "not mature" and at worst fiction.

Re: The Sound So Loud That It Circled the Earth Four Times

#35

Post by SerpentJoe »

kordless wrote: post #9
double0jimb0 wrote: post #6

Earlier quoted context omitted.

How does something like the Tzar bomb compare in terms of sound pressure? Would the immense volume of ejected material from the volcanic explosion move more air than a nuclear explosion? I'd guess lots of mass (air molecules) is just vaporized in a nuclear explosion, leaving much less mass to create pressure deltas.

Wikipedia says it was four times as powerful as Tzar Bomba, which would put it in the neighborhood of 200Mt. Technically Tzar Bomba was suppose to yield about 100Mt, but the scientists dialed it down a bit because they were worried about it.

My understanding is that the yield was halved by the use of a lead tamper, rather than a uranium one. The tamper is a shield around the core that slows down the explosion in order to consume the reactants more fully. In production they commonly make the tamper out of waste uranium, which undergoes fission during the blast and contributes a significant amount of energy, but if you don't need the boost then lead works fine, or anything else heavy. The other thing about uranium is it greatly multiplies the radioactive fallout (fusion bombs are actually pretty clean when lead is used), which may have contributed to the decision not to use it.

Re: The Sound So Loud That It Circled the Earth Four Times

#36

Post by jgalt212 »

kevinskii wrote: post #2

For anyone interested, I'd recommend Simon Winchester's book "Krakatoa": http://www.amazon.com/Krakatoa-World-Exploded-August-1883/dp... Also interesting are how quickly the volcano has risen out of the sea again after being totally obliterated, and how much life now thrives on it.

I second that opinion. Great book.

Re: The Sound So Loud That It Circled the Earth Four Times

#37

Post by D-Coder »

beloch wrote: post #23

To put this in context, the Krakatoa eruption released energy roughly equivalent to a 200 megaton bomb, which is roughly four times larger than the "Tsar Bomba", an H-Bomb which is the largest nuclear weapon detonated to date. The globe's average temperature fell 1.2 C after the eruption due to SO2 increasing the Earth's albedo. The Volcanic Explosivity Index (VEI) of the Krakatoa eruption was 6, and it's estimated t…

Eruptions are limited in size by the (lack of) strength and weight of the material keeping it suppressed. Asteroids have no size limit.

Disclaimer: I am a software engineer, not any kind of geologist.

Re: The Sound So Loud That It Circled the Earth Four Times

#38

Post by Arjuna »

jbert wrote: post #5

Nice. I hadn't thought of there being a limit (due to vacuum) to sound intensity. Reminds me of this recent comment on reddit: http://np.reddit.com/r/space/comments/2h9y9g/the_first_launc... "the Saturn V rocket produced a SWL (Sound Power Level) of about 220 decibels, which is sufficient to melt concrete nearby and set grass aflame a mile away,"

Speaking of the Saturn V... it's one of the most powerful machines that humans have ever created. It was equipped with five F-1 rocket engines, with each engine producing an absolutely staggering 1,500,000 pounds of thrust; that's a total of 7,500,000 pounds of thrust!

Can you imagine being tucked into the small, cramped Command Module, sitting on top of this magnitude of power at lift-off?

The whole thing, the technology, the sound, the people coming together to make it happen... it's soul-stirring.

https://www.youtube.com/watch?v=ygBxN5UiOaM

Re: The Sound So Loud That It Circled the Earth Four Times

#39

Post by 001sky »

Anechoic wrote: post #33
SEJeff wrote: post #14

Earlier quoted context omitted.

One thing I'm surprised you didn't mention is infrasound[1], which is sound so low that it can potentially damage the human body. Some of the newer non-lethal weapons the US military use for crowd control include a directional infrasound "gun" that basically vibrates your inner organs fast enough to make everyone super nauseous. [1] http://en.wikipedia.org/wiki/Infrasound

Some of the newer non-lethal weapons the US military use for crowd control include a directional infrasound "gun" that basically vibrates your inner organs fast enough to make everyone super nauseous. Do you have a cite for this? A "directional" outdoor infrasound weapon would be huge (10s of feet) and quick web search seems to indicate these types of weapon are at best "not mature" and at worst fiction.

http://www.globalsecurity.org/military/systems/munitions/acc...

Re: The Sound So Loud That It Circled the Earth Four Times

#40

Post by randall »

aatish wrote: post #3

Hey, I'm the author of the post (on twitter @aatishb). Thanks for voting it up. Would love to hear your thoughts and constructive feedback. Cheers. (PS the references linked to at the bottom of the post are packed with fascinating information about Krakatoa, for anyone who wants to dig deeper.)

This is one of my favorite things i've read on the internet in recent memory.
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