The Corner

News about Reality

Latest results from the physics labs suggest that reality is still there even when we’re not looking, thus resolving a conundrum memorably versified by Ronald Knox.

The Economist has a summary of some recent experimental work on Hardy’s Paradox, which states, very approximately, that subatomic particles may misbehave in very peculiar ways, but only when not being observed.

This week Kazuhiro Yokota of Osaka University in Japan and his colleagues demonstrated that Hardy’s paradox is, in fact, correct. They report their work in the New Journal of Physics. The experiment represents independent confirmation of a similar demonstration by Jeff Lundeen and Aephraim Steinberg of the University of Toronto, which was published seven weeks ago in Physical Review Letters …

The two teams used the same technique in their experiments. They managed to do what had previously been thought impossible: they probed reality without disturbing it. Not disturbing it is the quantum-mechanical equivalent of not really looking. So they were able to show that the universe does indeed exist when it is not being observed …

What the several researchers found was that there were more photons in some places than there should have been and fewer in others. The stunning result, though, was that in some places the number of photons was actually less than zero. Fewer than zero particles being present usually means that you have antiparticles instead. But there is no such thing as an antiphoton (photons are their own antiparticles, and are pure energy in any case), so that cannot apply here.

The only mathematically consistent explanation known for this result is therefore Hardy’s. The weird things he predicted are real and they can, indeed, only be seen by people who are not looking. Dr. Yokota and his colleagues went so far as to call their results “preposterous.”

[This is not, by the way, G. H. Hardy the mathematician, who makes such a striking appearance in Chapter 14 of Prime Obsession. This is a different Hardy.]