How does a bomb blast work?

I never knew that the shrapnel was sucked back in - I thought its momentum sent to outward only.
Very interesting.

I do... The best training I ever attended, was the Security Design course conducted by the US Army Corps of Engineers, which teaches you haow blast waves actually act, and how to mitigate them via proper security construction measures. CPT (Join to see)

From the science dude. Think about it from energy. First a gigantic release of energy that creates high pressure, heat, sound. That energy is projected out in all directions (like a ball or sphere) . But then, IF the explosive is big enough, there is an extreme low pressure valley created in the center. That causes the backwards wave. This happens in any explosion that is exothermic(releasing heat and energy). There is a great video of an atomic blast where the pressure wave makes trees go forward and back ahead of heat wave.

Cant say I have thought about this for many years. In the Navy my "C" School was Radiac Maint and decom. In school we had huge pictures of the test blast at Bikini Atoll. The vacuum of the blast and the sucking back in is what causes the mushroom cloud as all that force has to go someplace.

This is an overly simplified explanation but cuts to the chase. For those with no background it is an generic "ACME" heads up.

Nice graphics; this helps to explain the TBI process and what occurs when an IED goes off.