Light Travelling Faster Than Sound

January 26, 2013 10:31 AM

"Most films of nuclear explosions are dubbed. If they do contain an actual recording of the test blast itself.........it's almost always shifted in time so that the explosion and the sound of the blast wave are simultaneous. This is, of course, quite false: the speed of light is much faster than the speed of sound....." Unearthed recently from some Russian archive, this document of a nuclear detonation is one of the few films of its kind that includes a recording of the audio. The sound is not what you might expect.
posted by shackpalace (43 comments total)

A nice reminder that light travels faster than sound. And that we almost blew up the whole planet.
posted by LarryC at 10:36 AM on January 26, 2013 [5 favorites]

I didn't expect the noise of the blast, but I totally expected the "Holy shit!" that came after.
posted by infinitewindow at 10:40 AM on January 26, 2013 [2 favorites]

This is not from a Russian archive. It is from the the U.S. National Archives and Record Administration (NARA ID 25979). The Nuclear Secrets blog was pointed to the video in the NARA archives by a Russian correspondent, which is probably the source of the confusion.
posted by RichardP at 10:42 AM on January 26, 2013 [15 favorites]

Previously.
posted by shackpalace at 10:43 AM on January 26, 2013

A bit more chilling, this way, isn't it?
posted by Blazecock Pileon at 10:44 AM on January 26, 2013

The famous nightmare sequence from Terminator 2 did this right, despite it being a special effect. That scene is really chilling, the way that you see the flash hit far away, and for a moment everything is fine -- although you know that radiation is already sleeting through the bodies of the children, and that even if it stops there everyone is already dead. Then you see the shockwave ripple through the city, carrying an infernal fire and wind ahead of it, sweeping a ring of destruction outward at the speed of sound, so that the bodies of the cowering children and their families are first buffeted, then torched to ash, then finally blown away in the hellish wind.

It's a really powerful scene that captures the horror of nuclear war in a really archetypal and masterful way, as well as being (for an action movie) a fairly accurate portrayal of what a nuclear attack would look like. It is probably the best single scene in the movie. As well as being a really powerful and mostly-accurate portrayal of nuclear war, it also does a great job of conveying the Cassandra-like feeling of terror, frustration, and helplessness felt both by Sarah Connor and by anyone who has ever had a nightmare in which they tried to warn someone close to them of an impending danger but were somehow prevented from doing so.
posted by Scientist at 10:46 AM on January 26, 2013 [46 favorites]

And that we almost blew up the whole planet.

Don't be so pessimistic. We still might blow up the whole planet one day.
posted by dortmunder at 10:48 AM on January 26, 2013 [22 favorites]

The Restricted Data blog that posted this is highly recommended.
posted by FuturisticDragon at 10:48 AM on January 26, 2013 [3 favorites]

Detonation is at 2:22, sound is at 2:54. That puts the camera 11km away.

One hell of a bang, too, even over crummy laptop speakers.
posted by neckro23 at 10:52 AM on January 26, 2013 [4 favorites]

Actually, that's pretty much the sound I expected. A big boom.
Some background on the Upshot-Knothole test series (including Annie)
posted by Thorzdad at 10:52 AM on January 26, 2013

It's a really powerful scene that captures the horror of nuclear war in a really archetypal and masterful way, as well as being (for an action movie) a fairly accurate portrayal of what a nuclear attack would look like.

And it also was a dream I had myself been having over and over and over since about 1986....Yeah, that was a fun trip to the movies.
posted by EmpressCallipygos at 10:53 AM on January 26, 2013 [2 favorites]

We still might blow up the whole planet one day.

Global warming tends to make me think "not with a bang, but a whimper".
posted by Slothrup at 10:55 AM on January 26, 2013 [4 favorites]

I think you mean "a gasp".
posted by blue_beetle at 11:20 AM on January 26, 2013

Witnesses to this above ground testing have most likely died from multiple cancers well before old age, possibly from different exposure pathways besides gamma rays. The downwind effects have also contaminated millions of people and livestock for generations, and is still deadly for anyone who inhales radioactive particles kicked up from a dust storm.
posted by Brian B. at 11:22 AM on January 26, 2013 [3 favorites]

Established in 1943, Hanford released radioactive materials into the air, water and soil, releases which largely resulted form the routine site’s operation, though some were also due to accidents and intentional releases. Those who lived downwind from Hanford or who used the Columbia River downstream from Hanford were all exposed to elevated doses of radiation, which are presumed to have caused increased incidents of health problems and birth defects that generated widespread public concern over the public and environmental health implications of the site.
posted by KokuRyu at 11:24 AM on January 26, 2013 [2 favorites]

I don't have a cite, but supposedly the amount of radiation Hanford released into the Columbia River in the 1950's far exceeds the amount of contamination released into surrounding communities by the Fukushima disaster.
posted by KokuRyu at 11:25 AM on January 26, 2013

although you know that radiation is already sleeting through the bodies of the children

You'd be wrong. If you're far enough from the blast to hear the explosion several seconds after seeing it, the emitted radiation is the least of your worries. Sound travels at 340 meters/sec and the intensity of the gamma radiation quarters every time you double the distance. If you're about 3km away you'd hear the explosion in less than 10 seconds but receive less than 0.1% of the radiation yout get if you we're 100m away. And that's totally ignoring the amount of radiation the 3km of air between you and blast protects you from.
posted by schwa at 11:48 AM on January 26, 2013 [6 favorites]

Sounded like a shotgun. A really, really big shotgun.
posted by zardoz at 11:55 AM on January 26, 2013 [1 favorite]

Potentially stupid question: why is the flash of the explosion so silent? Like, it seems that the static and background noise in the recording fall away. Is this related to the physics of the explosion, or just an artifact of the recording technology?
posted by unknowncommand at 12:33 PM on January 26, 2013

My guess is that the electromagnetic pulse from the detonation may have screwed with the recording heads.
posted by ShutterBun at 12:44 PM on January 26, 2013 [3 favorites]

The EMP from the blast arrives at the same time as the visible light (for obvious reasons) as ShutterBun says. Whether they would mess with the recording I have no idea.
posted by Justinian at 1:03 PM on January 26, 2013 [1 favorite]

I found it really interesting that it was totally silent after the flash also--you'd think that would be the wilder part of the explosion, rather than the general chatter after the bang.

Watching old atomic test footage is always so strange. Hearing people's reactions and thinking about what they must have compared it to (big bombs!) culturally, before that distinctive enourmous white flash-mushroom cloud combo became the distinctive go-to image of "destructive force capable of killing us all" really seems to draw a temporal line for me.
posted by zinful at 1:37 PM on January 26, 2013

It was pretty much what I expected, though the EMP blast at the beginning was sort of neat.
posted by clvrmnky at 2:14 PM on January 26, 2013

The sound is not what you might expect.

I have to admit, with a set-up like that I was hoping for a Don Martin-esq "GZNING" or "ZOWT".
posted by lekvar at 2:48 PM on January 26, 2013 [7 favorites]

Related: Penn and Teller, on NASA's Successful Quantifying of Comedy Timing.
posted by Marky at 3:41 PM on January 26, 2013 [4 favorites]

If you're about 3km away you'd hear the explosion in less than 10 seconds but receive less than 0.1% of the radiation yout get if you we're 100m away. And that's totally ignoring the amount of radiation the 3km of air between you and blast protects you from.

Though, radiation is probably still gonna get you, as the fallout starts to come down a few minutes later, settling in your clothes and hair and lungs. You want a strong wind at your back or a light aircraft, or better still - no nuclear bomb at all! :)

it seems that the static and background noise in the recording fall away. Is this related to the physics of the explosion, or just an artifact of the recording technology?

No idea about the film technology of the day, but maybe the audio was being recorded directly onto the film in some form of sound on film format, and it's an artefact of normally inconsequential light leakage through the celluloid or lens elements?
posted by anonymisc at 3:42 PM on January 26, 2013 [1 favorite]

(On rewatching it, the silence leaving doesn't correlate obviously with the brightness fading, which is a point towards EMP, but OTOH, because the silence leaves when the film is still whited-out and over-exposed, the brightness could have been rapidly dropping for some time before we see any drop of brightness on film, so it's not a slam-dunk either :-/ )
posted by anonymisc at 3:58 PM on January 26, 2013

You beat me to it, anonymisc. I was just typing up the same theory, practically word for word.
posted by ShutterBun at 4:00 PM on January 26, 2013

The picture has artifacts of both video (the bright bands and ringing at the edges, the periodic vertical flutter, the horizontal bands that appear sometimes) and film (you can see film damage here and there). I'd guess they had an electronic camera (orthicon or vidicon) which sent the picture to a remote film recorder— no videotape at the time, remember— and that overmodulation on either the video or the audio channel on that connecting link could interfere with the other. Notice how at :20 or so, someone's speech causes horizontal bands in the image, spaced as you might expect if the audio were leaking into the luma channel. It doesn't seem unlikely that a bright image could bleed over into the audio.

EMP isn't very likely: they were 11km away from a 16kt, low-altitude (100m) burst. AFAICT there wouldn't have been much EMP beyond a mile or so, and if there were, it's a brief enough phenomenon that it would have been a pop on the audio channel, not an extended outage.
posted by hattifattener at 5:49 PM on January 26, 2013 [2 favorites]

Yeah, I think you have it, hattifattener. The buzzing sound right at the blast seems like an overexposed image bleeding into the optical audio track along the edge of the film.
posted by charlie don't surf at 6:04 PM on January 26, 2013

That film just feeds into my worst nightmare scenario. That scene from T2 fed it as well. I'm off to hug the cat dammit.
posted by arcticseal at 6:07 PM on January 26, 2013

Isn't "Creepy Nuclear Test" redundant?
posted by Smedleyman at 6:19 PM on January 26, 2013

Nah, I don't find them creepy, I find them viscerally terrifying. Very different sensation. Especially when I remember that this test was of a relatively tiny bomb, early in the development of nuclear weapons. Most of the US' current warheads are 10 times more powerful than this one; many are 100 times more powerful, and the largest we've ever deployed is over a thousand times more powerful than this one. (It's possible to make even larger bombs, but it turns out there's not much point.)
posted by hattifattener at 6:33 PM on January 26, 2013

I can't believe we set one of these off and had a reaction other than, "holy crap! Yeah, let's not do that again."
posted by tylerkaraszewski at 6:45 PM on January 26, 2013

Scientist: "It's a really powerful scene that captures the horror of nuclear war in a really archetypal and masterful way, as well as being (for an action movie) a fairly accurate portrayal of what a nuclear attack would look like. It is probably the best single scene in the movie. As well as being a really powerful and mostly-accurate portrayal of nuclear war, it also does a great job of conveying the Cassandra-like feeling of terror, frustration, and helplessness felt both by Sarah Connor and by anyone who has ever had a nightmare in which they tried to warn someone close to them of an impending danger but were somehow prevented from doing so."

Had a night-mare dream about this scene last night. Then I thought about this Bob's Burgers scene...
posted by stratastar at 7:23 PM on January 26, 2013 [1 favorite]

According to the Upshot-Knothole Annie Wikipedia page, this test was nationally televised.
posted by 1367 at 7:43 PM on January 26, 2013

After six decades, New Mexicans still coping with Trinity blast

Hawkes estimated that 95 percent of the girls she went to school with in Alamogordo eventually contracted some form of cancer or thyroid disease. "I hope somebody pays attention to what's (been) going on," Hawkes said.

posted by Brian B. at 7:59 PM on January 26, 2013 [1 favorite]

Sounded pretty similar to one of the terrorist bombings i heard going off in Buenos Aires back in the 90s. Like if you let a huge metal gate fall on its side.
posted by palbo at 8:47 PM on January 26, 2013

It's possible to make even larger bombs, but it turns out there's not much point.
Interestingly, during the Cold War, this was not seen as entirely true. US academic Herman Kahn, who founded the Hudson Institute thought it would be worth building a bomb or bombs so big that when detonated they would crack the earths crust and destroy all advanced life, plunge the planet into nuclear winter and all that, a logical extension of MAD doctrine. The idea being if the Russkies attack us, we destroy the planet.

Supposedly, the Russkies themselves went some way toward developing such a system, with cobalt salted bombs on deadman switches... Personally I think on both sides it was empty posturing like a lot of MAD/ Cold War stuff. But some people at least thought there was a point.

When I was 8 or so I dug a bomb shelter in the back yard....on the advice of our home encyclopedia set.
posted by jackbrown at 10:28 PM on January 26, 2013 [1 favorite]

If I ever own a race horse or a yacht, I will name it Upshot-Knothole. Lets just hope I am never rich enough to own both, because I don't have any other names picked out.
posted by Grandysaur at 11:06 PM on January 26, 2013

You gotta be careful with those damn cobalt bombs—first you end up on the set of Hello Dolly!, then some dick from the NRA kills all life on Earth. Bad news all 'round.
posted by sonascope at 5:59 AM on January 27, 2013

Though, radiation is probably still gonna get you, as the fallout starts to come down a few minutes later, settling in your clothes and hair and lungs. You want a strong wind at your back or a light aircraft, or better still - no nuclear bomb at all! :)

Oh definitely. I wasn't trying to say nuclear bombs are harmless pyrotechnics. At ~3km you're probably going to get hit by the shockwave/firestorm if it's a largish (i.e. bigger than Hiroshima/Nagasaki) bomb. And yeah - fallout. Just wanted to point out that the harmful radiation diminishes in strength _very_ quickly as distance increases.
posted by schwa at 1:30 PM on January 27, 2013

Global warming tends to make me think "not with a bang, but a whimper".

The world is going to be just fine. There's basically nothing that we can do to permanently fuck things up.

Humanity, on the other hand...
posted by kdar at 5:35 PM on January 27, 2013