One way to obliterate an atom is to shoot it with the planet's most powerful X-ray gun. Linda Young tried that experiment in October 2009, when she was testing the newly opened X-ray free-electron laser at the SLAC National Accelerator Laboratory in Menlo Park, California. A single pulse from the US$420-million machine packs the same energy as all the solar radiation hitting Earth at that moment, but focused down to one square centimetre. “It will destroy anything you put in front of it,” says Young.
When the laser pulse slammed into the neon atoms in that experiment, it made them explode, stripping away each atom's 10 electrons within 100 femtoseconds (1 femtosecond is 10−15 seconds). But it was the manner of this destruction that most interested Young, who heads the X-ray science division at Argonne National Laboratory in Illinois. The X-rays first removed the atom's inner electrons, leaving the outer ones in place. For a brief moment, the neon atoms in the path of the laser became hollow.
That exotic form of neon is one of a number of strange species created by physicists intent on contorting atoms. Some teams have inflated atoms to the size of dust particles. Several research collaborations are creating anti-atoms out of antimatter. And others have loaded atomic nuclei with protons and neutrons in the quest to forge new superheavy elements. Some of the experiments aim to investigate atomic structure; others use atoms as the first steps in modelling more complicated systems. They are all descendants of the revolution in atomic theory catalysed by Danish physicist Niels Bohr 100 years ago. But Bohr would have had difficulty imagining how far scientists could go in poking and prodding atoms into such extreme forms.