Gary S. Settles in American Scientist:
Recent attacks by terrorists using improvised explosive devices have reinforced the importance of understanding blasts, explosions and the resulting shock waves. These waves can be powerfully damaging in their own right, but in addition, studying them can help to quantify their originating explosions and can provide insight into how buildings and airplanes can be hardened to resist damage resulting from such blasts.
Their almost-total invisibility has given shock waves a mystique that has been exploited by Hollywood in countless scenes where explosions send heroes diving for cover. Like sound waves, shock waves are as transparent as the air through which they travel. Usually they can only be seen clearly by special instruments under controlled conditions in the laboratory.
Now, however, our research group has taken modern high-speed videography equipment and combined it with some classical visualization methods to image shock waves from explosions and gunshots in more realistic environments. This allows us to capture the development and progress of these wave fronts on a scale that has not been possible in the past.