Tuesday, July 31, 2012

Wanted: Schrodinger's Cat, Dead AND Alive

I've always been fascinated with the idea of Schrodinger's Cat. For those who don't know what that is, I'll elaborate:

Picture a cat. In a sealed box. A box with an odd-looking machine inside. This machine will randomly dispense poisonous gas, which would instantly kill the cat. Well, not quite randomly. There's a nifty little gadget called a Geiger counter hooked up to the gas chamber. A Geiger counter is a device that detects certain particles passing through it - particles so tiny or volatile they can pass through matter; X-rays, for instance. The idea is that when the box is opened, the cat will be either dead or alive.

However, the interesting bit is that before the box is opened, the cat is said to be both dead and alive. This is because, due to the random nature of the machine, we cannot determine for sure whether the cat is dead or alive without opening the box. But ah - whoops! If we open the box, we may well change the state of the cat, and therefore, still be none the wiser about whether the cat was actually dead or alive before we opened the box.

It can be likened to the Heisenberg Uncertainty Principle, one of the most interesting facets of modern physics and/or science in general. It states that no quantity can be fully measured to perfect accuracy - not only because we have no method of recording a measurement of infinite precision, but also because the act of measuring itself, on such a microscopic scale, changes the quantity being measured.

Insert random Heisenberg joke here:

Heisenberg is out for a drive and is going quite fast, when a cop pulls him over.

"Do you have any idea how fast you were going?" the cop asks him.

Heisenberg replies, "I might have, but blast you, you just had to go and measure it!"

Another conundrum that provides great food for thought is quantum physics. Without going into much detail, the idea is that small packets of matter (the smallest known, in fact) called quanta, are constantly going in and out of existence. This changing state is governed solely by probability, and the act of observing a quanta forces it to collapse into one of its probable states. In other words, until you look directly at something, it may or may not be where you think it is. It's probably reasonably close - but its exact shape and details of its existence (such as viscosity, temperature, and structure - things all determined by its atoms and hence, its subatomic quanta) are not set in stone until you actually observe it. When observed, each particle must collapse into one of the possible states, according to the probability of each.

This probability is identical to, say, rolling a six-sided die. Half of the time, the numbers 4 through 6 will be rolled. One third of the time, the numbers 1 or 2 would be rolled. Lastly, 3 is only rolled one sixth of the time. If these three outcomes have the same probability as the appearance of different states of a certain quantum particle, then one state will occur three times more often as the others - the state that appears half of the time (rolling 4, 5, or 6). The second state, rolling 1 or 2, occurs twice as often as the third state (rolling a 3). So each time you view this quantum particle, you've just rolled the six-sided die, and the particle you see (its location and properties) are determined by rules of probability, much like those discussed here.

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