Why Is Mercury, a Metal, Liquid at Room Temperature?
By Shlomo Maital
Ever wonder why mercury, a metal, is liquid at room temperature – the only metal to be have so? I’m sure most of us have seen mercury, have realized it is a metal, yet one man followed up to find the answer. His name is Peter Schwerdtfeger, and he won the Rutherford Medal this year, New Zealand’s highest science prize. Schwerdtfeger is on the faculty of Auckland’s Massey University (where my wife spoke on Friday).
According to Schwerdtfeger, the reason gold is golden in color and mercury is liquid has to do with quantum effects.
According to Schwerdtfeger: “For a very long time people believed that relativistic effects are of no importance to chemical systems because from Einstein’s special relativity we know that if particles reach very high velocities close to the velocity of light, then special relativity becomes important. People thought that for electrons in the valence shell, which are important for doing all the chemistry but move rather slowly, that you wouldn’t expect that relativity effects would be important.” But they are. Hard for me to understand and explain in a short blog what those special relatively effects are – enough to understand that Schwerdtfeger took on the physics establishment and proved that relativity is important even for electrons travelling very slowly.
“With increased computer power and a team of collaborators, including a bold doctoral student, he was able to show that without the effects of relativity, mercury would be solid at room temperature and melt at 82 degrees Celsius.”
It took him years to get his breakthrough paper published. When he submitted the first, the reviewer told him there had to be a mistake – because it violated what was known at the time. Eventually it was published.
There are several lessons here. First, if you are a doctoral student, pick a really big touch hairy hard question to research. I myself failed to do this and regret it ever since.
Second, Schwerdtfeger says: ‘If you only invest in commercial science and completely neglect basic science you probably get neither of them.” Under the current Conservative government of PM John Key, government spending in New Zealand has been slashed to the bone, university lecturers have been fired, research grants cut back. Key is vastly unpopular here, but democracy’s wheels grind slowly. Until the wheel of democracy comes around, great damage will have been done to New Zealand’s universities.