THE FIRST FIFTEEN MILLISECONDS
GJH member John Daily, who happens to be a nationally recognized crash expert, finds his deepest joy in crashing vehicles into each other. It could be a mini cooper and a cement truck, a couple of pickup trucks, maybe a corvette and a cadillac. T-bone, rear-end, head-on, fast or slow, it doesn’t matter to him. He loves it all. Because of people like John and the many-thousand crashes his ilk have engineered or reverse-engineered, there is not much we do not know about how most any vehicle ever made will react in a crash. All you have to do is give him the relative speeds, vectors, and mass, and he can write the script for what will happen next. This is actually useful stuff. Armed with this exhaustive knowledge base, crash experts like John can also look at a crash site and tell us – in their unique lexicon of delta v’s, occupant kinematics, Hooke’s Law deformations, and yaw rates – what already transpired.
John likes to point out that almost everything that will take place during a collision is determined in the first 15-thousandths of the second in which metal meets metal. In this critical window of time, the airbag sensors will wake up and decide if they are going to deploy, one vehicle will decide if it is going to go over, under, or through the other, gas tanks will be situated to explode, or not explode, and so forth, in much the same fashion that the fabric of the universe is believed to have been predetermined in the first sparks of the big bang.
A lot of geologists love this kind of stuff as well. The difference – if there really is a difference – is that they study the biggest collisions in earth’s history, and they substitute continents for vehicles. While they are decidedly disadvantaged by the relatively small number of collisions that rise to their attention, they have the unique advantage of nearly frozen time in relation to the crashes they study. And for purposes of our next lecture, this is where it gets especially interesting.
The Greater Caucasus mountains are shrouded in mystery. Long inhabited by a diverse group of peoples, the governance of whom has been variously asserted but rarely accomplished by a long line of expanding empires, the Caucasus mountains constitute a region where few are certain of what will happen next. And as continental collisions go, this one is particularly young. In the parlance of crash experts, this one is still in the first fifteen milliseconds.
Back in the Oligocene, the Arabian plate separated from the African plate along the Red Sea rift and began its journey north, running several red lights and bumping into other traffic along its way to the inevitable head-on smash up with the Eurasian plate. In some respects, this wreck is just beginning in earnest now, as the subduction of the last of the oceanic basement once separating these plates gives way to true continent-to-continent collision. Imagine a corvette that is slamming under a cement truck. Now imagine the corvette, in the first 15 milliseconds of the crash, suddenly becoming another cement truck. There is no other place on earth where a continental collision can be studied at this critical and early phase. This Tuesday, (July 19th) at the Teton County Library Auditorium at 6:00 pm University of Michigan Professor Nathan Niemi will give us his take on these fascinating events, what we know now, and what we hope to learn with more study. A better understanding of what is happening right now in the Caucasus Mountains will lead to better predictions about what will happen next. It will also help earth scientists who are reverse-engineering far more ancient continental collisions. This is great stuff and we hope many can attend.