The Impossible Observed

Abstract

In 1979 in Heidelberg, Germany, Dr. Werner Neuhauser looked up from the eyepiece of a low-power microscope and fancied he heard the ghost of Mach whispering: “Now I believe in atoms.” Neuhauser had just glimpsed what appeared to be a bright blue star floating in the void; it was a single barium ion, caught in an electromagnetic trap and fluorescing in a laser’s beam. Thus transpired the first observation of an isolated atom using a lens; soon one would be glimpsed with the naked eye as well. (When I was a child, elementary science textbooks claimed that no one would ever see an atom with the naked eye. The authors had erred by assuming that smallness was the important issue; actually, brightness and isolation from other atoms are what matters. The laser-stimulated barium atom produces 10⁸ photons per second; your eyes can collect several thousand. The normal retina is sensitive to even a few photons, so you can see the atom, just as you would a distant star or any other bright, isolated object.)

We never experiment with just one electron or atom… any more than we can raise Ichthyosauria in the zoo. —Erwin Schrödinger, 1952

Here, right now, in a little cylindrical domain... in the center of our Penning trap resides positron (or anti-electron) Priscilla, who has been giving spontaneous and command performances of her quantum jump ballets for the last three months. —Announcement from Hans Dehmelt’s laboratory in Seattle, 1984