They are surely the most horrifying offshoot of modern technology - nuclear warheads which can smite hundreds of thousands of people dead within seconds, and leave lasting scars on a landscape for generations.

And while most of us will have seen archive footage of nuclear explosions before, one thing we are unlikely to have heard is their sound.

For, according to one expert, most films we see of a nuclear blast use stock 'explosion' sound effects for the bang - and audio footage is few and far between.

But Alex Wellerstein, an historian of science at the American Institute of Physics, has shared a unigue video of a blast during America's testing of nukes in the Yucca Mountain area of Nevada during the 1950s.

The historian was sent the video below from a Russian colleague, and has now shared it on his blog.

Wellerstein wrote: 'Most films of nuclear explosions are dubbed. If they do contain an actual audio recording of the test blast itself (something I’m often suspicious of - I suspect many were filmed silently and have a stock blast sound effect), 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, and the cameras are kept a very healthy distance from the test itself, so in reality the blast wave comes half a minute or so after the explosion. Basic physics that even a non-technical guy like me can understand.

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