In the foothills above Palo Alto, California, physicists have set up an extreme obstacle course for some of the world’s fastest electrons. First the particles are accelerated through a 3-kilometre vacuum pipe to almost the speed of light. Then they slam through a gauntlet of magnets that forces them into a violent zigzag. They respond with a blast of X-rays so fierce it could punch through steel.
But the scientists at the SLAC National Accelerator Laboratory have no interest in weaponry. Their machine, one of the world’s most powerful X-ray free-electron lasers (XFELs), is a tool for studying challenging forms of matter, whether compressed to the kind of pressures and temperatures found deep inside a star, or folded into the complex tangle of a protein molecule.
Again, this is possible due to advancement in accelerator physics, which is now a separate field of physics in itself. Only when the "instrument" is available can scientists from other fields use it to look deeper and in greater detail at many of the things they study.