that is, after the item had passed through the first but before it struck the back wall. That task seemed insurmountable. But now that experiment has been tried out, and the results are rather mind-boggling.
The team in Australia turned thought experiment into lab reality by using lasers. Their subject matter was not a photon but a helium atom which, though much more massive than a photon, would also theoretically act like a photon. That is, it would also exist in an indefinite state, then act either like a particle or like a wave, once observed. The lasers they used served as a pair of grates, one before the other, with the second grate randomly dropped in.
What they found is weirder than anything seen to date: Every time the two grates were in place, the helium atom passed through, on many paths in many forms, just like a wave. But whenever the second grate was not present, the atom invariably passed through the first grate like a particle. The fascinating part was, the second grate’s very existence in the path was random. And what’s more, it hadn’t happened yet.
via Second Nexus
