Asked by: Alex Jackson, Cambridge
In the desert of New Mexico on 16 July 1945, an international team of scientists succeeded in creating a device that reached temperatures of several hundred million degrees centigrade – far in excess of the 15 million degrees at the Sun’s core. That device was an atomic bomb of the kind dropped on Japan a few weeks later.
Similar temperatures are now routinely and safely generated in nuclear fusion machines, like the Joint European Torus in Oxfordshire. The highest temperature ever reached under controlled conditions is an astonishing two billion degrees. It was created in the so-called Z-machine at the Sandia Laboratories, New Mexico, which uses incredibly high electric currents and magnetic fields to release radiation from atoms.
It’s not always necessary to use such dramatic means to reach high temperatures, however. In 2005, scientists at the University of Illinois at Urbana-Champaign triggered temperatures of over 20,000 degrees – far hotter than the surface of the Sun – by crushing vapour trapped in tiny bubbles.