Science with Richard Bleil
It’s not uncommon to hear about Schrödinger’s Cat. In fact, I made a pun of it today. Having seen a spider that built its web between my window and screen, I posted a photo saying it’s Schrödinger’s Spider because it’s neither in the house, nor out of the house, but is in and out both simultaneously.
That’s what people understand. It’s neither, and both simultaneously. But what it really means, and how it’s related to quantum theory is something that few people really understand.
Heisenberg proved that classical physics fails at the sub-atomic level, because we cannot, exactly, measure position and momentum simultaneously. There will always be an inherent error, and error insignificantly small at the macroscopic level where we, you and I, live, but when you’re talking about something as small as an electron, that error is huge.
Along comes Schrödinger, who says, okay, so we cannot know everything about the behavior of electrons, so let’s work with probability instead. We may not know where the electrons are or how they are moving, but maybe we can predict where we will most likely find them. Taking a cue from hydrodynamicists studying waves, he applies their wave equation to electrons and advances science by a century in one step.
What quantum theorists like Schrödinger came to realize is that there are things possible in the quantum world that just make no sense to us in ours. Electrons are free to move through zones where they are not allowed to exist at all (called a “node”), so basically the only way that they can move through it is to simply stop existing on one side and begin existing on the other side without traveling. For us, you and I, this is impossible, except perhaps in science fiction.
Schrödinger’s Cat is an analogy for this. For example, there is a feature of electrons called “spin” that nobody understands, and, no, it’s not an electron spinning clockwise or counterclockwise. Anybody who believes this, including quantum mechanical book authors, understands spin least of all. Heisenberg has proven that we cannot know what the electrons are doing, and electrons are as much waves as they are particles (proven by De Broglie) so shoving an axis through it makes no intuitive sense at all. No, we cannot know what spin is, but it has been experimentally verified to exist. The electrons can be either spin up, or spin down. Well, not really.
See, although spin is a physical property of the electrons, they actually exist in both spin up and spin down simultaneously, unless, and until, some moron tries to measure the spin. Once the spin is being measured, then and only then do they assume one of the spin states.
This is the paradox to which Schrödinger’s cat applies. Put a cat in a box with atomic poisons that has and equal probability of going off at any given moment, and the question becomes if the cat is alive or dead. The reality is that it is both, literally both, alive and dead at the same time until somebody “performs the experiment” by lifting the lid to see if the cat is alive or not.
The odd thing about quantum theory is that everything the has been predicted, and can be experimentally tested, as been, and every time it turns out to be true regardless of how bizarre it might seem.
Some years ago, a group of physicists tested Schrödinger’s Cat with a Beryllium atom. Beryllium has four electrons, so it was perfect for the experiment. They shot this beryllium with three lasers, all very finely tuned, and all with a specific purpose. In an extremely high vacuum, they shot the beryllium with the first laser, knocking off one of the electrons. This created a charged beryllium cation, with one unpaired electron.
Because it was charged, they could isolate it in a magnetic field, and use spectroscopy to verify that it was alone. According to Schrödinger’s cat analogy, that unpaired electron was both spin up and spin down at the same time so long as nobody tried to measure it. So, the second laser was tuned to the exact frequency to “excite” just the spin up state to a higher energy level. Now this beryllium existed in both the ground (lowest energy) level and an excited level (higher energy) simultaneously. It was like having the beryllium both hot and cold simultaneously, much as you might feel when you’re not well, both burning up and not being able to get enough blankets.
The third level pushed the excited state beryllium ion away from the ground state. Spectroscopically they proved that the beryllium ion was still alone in that chamber, so it was not split, and yet it existed, simultaneously, in two locations in space at the same time, separated by a distance roughly ten times the diameter of the ion. It would be like a happy you, and a sad you, but the exact same you standing ten feet apart looking at each other.
Bleil's Banter 