For a start, quantum physics is really well-established. It’s had about 100 years of complete success as far as experiments. In fact, quantum physics is so accurate that we physicists are getting desperate (let’s be honest here: we’d love it to fail, since this opens the door to discovering a new theory, and for a physicist this is the easiest way of entering the Physics Hall of Fame). Even the weirdest of quantum predictions (what Einstein termed “spooky action at a distance”) are now established beyond reasonable doubt. Quantum objects seem to know about each other in a way not allowed in the classical world, and even when these objects are far apart they act as an inseparable whole.
A few years back, the Steelers were playing the Cardinals in the Super Bowl, and the game came down to the wire.
In one of the most famous plays in Super Bowl history, quarterback Ben Roethlisberger scrambled to his right and fired a pass to the corner of the end zone, where Santonio Holmes caught the ball for the go-ahead touchdown.
Or did he? Ruled a touchdown on the field, the play was close enough that the officials needed to review it via video replay.
For a few minutes, though the play had happened on the field, the result of the play was in limbo.
Finally, the ruling came back that the receiver did keep both of his feet inbounds, and the touchdown was confirmed, notwithstanding Cardinals fans who felt Santonio’s toes had grown an extra inch in the meantime.
Another, much more famous example of a decision waiting to happen, was the O.J. Simpson trial. While maybe not the “trial of the century,” it was undoubtedly the trial of the 1990s, with seemingly every TV station in the country riveted to it. And it too went through an important delay, this one being the announcement of “guilty” or “not guilty.”
In both the examples above, and many others like them, we find that often we have to wait before learning about a result, even when that result – a football play finished, a jury decision reached – has happened. This, perhaps surprisingly, is also how nature operates.
The Austrian physicist Erwin Schroedinger created perhaps the unluckiest cat story of all time.
Schroedinger’s cat is a parable about the meaning of quantum physics. While patent nonsense at the level of everyday life – the cat is either alive or dead – the subatomic world doesn’t work in such a straightforward fashion. A particle can be said to have a spooky blend of existence and non-existence… until one opens the box.
Imagine, he said, placing a live cat into a sealed box. Along with the box is a radioactive atom with a half-life of one hour, plus a device (the details here don’t matter) that will kill the cat when it detects a radioactive decay. Also assume the cat is otherwise safe – there’s sufficient air to breathe, and so on.
You can’t tell anything about the cat from the outside. The odds of the atom decaying are exactly one-half during the hour. Without opening the box, can you tell: Is the cat alive or dead? Or something in between?