Welcome Physics World  August 2020

Measurements vs discoveries

Tiny temperature changes. (Safa Hovinen, Merkitys)

Enrico Fermi once suggested that all experimental results fall into just two categories. “If the result confirms the hypothesis, then you’ve made a measurement,” he said. “If the result is contrary to the hypothesis, then you’ve made a discovery.”

Much as I hate to contradict one of the biggest names in 20th-century physics, I can’t help but think that Fermi was being rather too dismissive about measurements here. For one thing, contrary results have a nasty habit of turning out to be errors, not discoveries. For another, the supposedly inconsequential act of making a measurement is often anything but simple – as Fermi, a top-notch experimentalist as well as a distinguished theorist, surely knew.

The articles in this Physics World Instruments and Vacuum Briefing testify to the central role that precise, accurate and creative measurements – many of them made in the teeth of hefty technological challenges – play in advancing scientific knowledge. By extension, the issue also celebrates the tools that make such measurements possible. The first section, “Vacuum & cryogenics in action”, highlights a handful of recent measurements – or should I say discoveries? – that would not have been possible without advanced vacuum pumps, cryogenic coolers, or both. Later sections on metrology, spectroscopy, and microscopy explore how standards and instruments are evolving to support ever-more-demanding experiments and conditions. Finally, sections on quantum and applied instrumentation illustrate what can happen once these advanced technologies are put to use in new ways – whether that’s measuring the local force due to gravity or tracking mosquitoes during a solar eclipse in Tanzania.

All in all, there’s a wonderful diversity of technologies on display here. I hope you enjoy reading about them, and if you’d like to share your own stories about discoveries and the measurements that made them possible, please don’t hesitate to contact us at pwld@ioppublishing.org.