Adam Frank for McGraw-Hill

Astronomy may be the oldest profession in the world but that doesn't mean it can't learn entirely new ways to go about its business. In just the last few years a new technology has emerged that may free astronomers from their complete dependence on telescopes and, for the first time, allow them to bring the physical conditions in faraway stars down to Earth.

Astronomy has always been an observational, not an experimental, science. What you see on the sky is what you get. Researchers can't control conditions in the stuff they study. They can't tweak the knobs on a supernova or change settings on a gamma ray burst. They must take what comes to them in the few photons their telescopes can catch. But telescopes might not be the only tools at astronomers' disposal. Over the last few years a handful of scientists have been using giant lasers the size of football fields to do astrophysics in a radically new way. The massive, multi-million dollar racks of steel, laser glass, and filters that astronomers are beginning to play with were originally designed to study what is called Inertial Confinement Fusion (ICF). ICF is currently the most popular scheme for tapping the Sun's power source (nuclear fusion) for terrestrial energy demands.

Fusion is a deceptively simple process. Squeeze atoms of light elements together hard enough and they will fuse into heavier elements and give up some energy along the way, as described by Einstein's equation E = mc2. The Sun gets all the squeeze it needs for fusion from the gravity of its billion billion billion tons of gas. We humans don't have it so easy. Over the last twenty years physicists have been building ever more powerful lasers to do the squeezing for them. The Omega Laser system at the University of Rochester is currently the largest and most powerful ICF laser in operation. It can deliver 60 thousand joules of energy into a space the size of a sand grain. For fusion studies the purpose of getting all that energy into such a small space is to implode a small pellet of hydrogen to temperatures and densities similar to that in the sun, which forces hydrogen atoms to fuse.

All that power under such exact control can make for good astrophysics too. Matter caught at the laser's focus is vaporized into a super-hot, super-high speed plasma (plasma is state of matter where electrons are torn off atoms, which creates a soup of charged particles). While ICF engineers want to use the plasma as the fodder for making fusion power, astrophysicists are realizing it has other uses as well. For nanosecond increments of terrestrial time, the plasma in the target chambers of these giant lasers host the same physics exotica that occur in the extremes of interstellar space. What astronomers do with these recreations bits of the cosmic drama may be limited only by their imaginations.

A particularly compelling example of this new form of laboratory astrophysics comes from a series of experiments that create miniature versions of supernovae blastwaves. Supernovae are titanic explosions that mark the end of a giant star's life. The blastwave from a supernova can sweep up everything in its path for tens of light-years. Up to now supernovae were such extreme events that astronomers could only study them in full detail using sophisticated supercomputer simulations. ICF lasers can also create blastwaves by focusing their enormous power onto a small target. Because the physics governing these blastwaves doesn't care about scale, the light year sized supernova blastwaves can be studied by examining their millimeter sized ICF cousins. The laboratory experiments have already allowed astronomers to test their computer models in a way thought to be impossible just a few years ago and future experiments are likely to lead to fundamental insights into how supernova evolve.

Investigations of supernova behavior, it appears, might be only the beginning. Experiments are already underway to explore everything from the cores of giant Jupiter-like planets to the nature of light year long hypersonic jets from newly born stars. As the fusion power machines become ever more powerful other possibilities also arise such as creating small clouds of anti-matter to test theories of gamma-ray bursts, the most energetic explosions in the universe.

It's a heady time as the new field gains momentum. Will the giant lasers emerge as new tool for astronomy? Will astronomers truly learn to recreate the universe in the Lab? Only time will tell, but this is definitely a channel to which you will want to stay tuned. Old dogs can be taught radical new tricks.

Astrophysics at the NIF SuperLaser System:
http://www.llnl.gov/science_on_lasers