Somewhere in a dim and distant chemistry lesson we were first introduced to the atom. We learned that it has a nucleus (a bit like the sun) and that around the nucleus, dutifully obeying classical mechanics, orbited the electrons (much like the planets). The simplicity of the idea seduced even the great Niels Bohr. Everything seemed so perfect, so beautifully inter-related: from the atomic to the cosmic, the universe resonated with harmonious similitude. But, of course, it couldn’t last.

Before long, we got a little older and encountered Erwin Schrödinger – the man with the power to split reality and whose mind birthed the equation that would shatter our illusion. We learned, to our horror, that quantum theory says ‘no’.

The veil was torn from our eyes and the electron’s true nature was revealed – elusive, treacherous, chimeric; the unholy offspring of the union of wave and particle. Everywhere and nowhere, the electron was impossible to pin down, and suddenly uncertainty was the only certainty. We stared, aghast, as tutors’ chalk calmly described the loops and lobes of the mathematical prisons that surround the nucleus, their unfamiliar lines mutely stating ‘it’s probably in there’.

Well, some scientists in Germany have now brought the classical and quantum worlds a step closer together to make those electrons behave as Bohr thought they ought. By putting an electron in a highly excited state and confining its slippery nature with some well-chosen electromagnetic fields, they’ve succeeded in creating atoms whose electrons orbit the nucleus in just the circular, ‘planetary’ paths proposed by Bohr; a tiny replica of a solar system. Indeed, the very trick they use has an astronomical inspiration – the Trojan asteroids orbit in the same path and with the same period as Jupiter, without spreading out, owing to the stabilising action of Jupiter’s gravity. In this atomic analogue, the electromagnetic field, tuned to oscillate at the frequency of the electron’s orbit, supplies the stabilising force that stops the electron wave packet spreading out around the atom.

With electron in such highly excited states, the atoms themselves are pretty huge – on the order of hundredths of millimetres, bigger even than some biological cells.

The group think it should now be possible to excite further electrons into such states to create multiply-excited ‘planetary atoms’. And as the classical meets the quantum, we should gain a better understanding of the relationship between these worlds.

So well done, Burgdörfer et al, for standing up to the electron and showing that with a little cunning and some good old brute force, we can at last recapture the lost atoms of our youth.

Philip Robinson

                  

Source:
http://prospect.rsc.org/blogs/cw/?feed=rss2