G. I. Taylor

They show a remarkable spherical shockwave expanding rapidly outward from the explosion site.

One person who was allowed to observe the original atomic test was a British physicist by the name of Sir Geoffrey Ingram Taylor.

A few years later, Taylor figured out how to use those photographs of the blast wave to calculate and publish the energy of the explosion, equivalent to about 20,000 tons of TNT.

That explosion energy was highly classified at the time, but the US military had unknowingly given it away by showing off photographs of the explosion.

Taylor's calculation relied on our understanding of the propagation of shockwaves.

The Trinity atomic test was a nearly perfectly spherical blast wave, and Taylor was able to use reasonably simple arguments to estimate the explosion energy.

Nowadays, we can do the same kind of thing in astrophysics, except for instead of an atomic test, we might be thinking about a supernova or perhaps a planet colliding with a star or a black hole crashing into an accretion disk.

Explosive events abound in the universe, and astrophysicists have paid attention to the lessons taught by G.I. Taylor, which is that you can learn a whole lot about what happened by looking closely at how the shockwave propagates.