Divrei ben Abuya

In the Babylonian Talmud, Elisha ben Abuya was a great sage who lost his faith in God. So great was he that his and subsequent generations continued learning from him - to the extent that the authors of the Talmud needed to create a story that would serve to legitimise his teachings despite his apostasy. His lesson is a lesson for us all: that great stature is not contingent upon blind faith, nor high learning upon the observation of Torah precepts.

September 22, 2006

Killing Cats

There is a particular principle of theoretical physics named (after its author) "Heisenberg's Uncertainty Principle". In a nutshell, this principle states that it is impossible (in the case of some minute particles) to guage both their speed and their location. By measuring their location, one alters the speed at which they move; by noting their speed, one moves them. Some have used this principle, and its natural corollary that not everything about our universe can be known, to argue against the fatalist philosophy that suggests that all events are predetermined on the basis of the universe constituting a closed system of information.

In any case, a German physicist by the name of Schroedinger developed a metaphor for the representation of Heisenberg's idea. The metaphor runs as follows:

Suppose I take a cat, and I place it within a "black box" (so named by virtue of the fact that its contents are either invisible or unknown). Alongside the cat, I place a radioactive atomic nucleus and a canister of poison gas. Should the nucleus decay, a particle will be emitted that will trigger a mechanism within the canister and fill the box with gas. Thus dies the cat. Over the course of one hour, there is a 50% chance that the event occurs.

As Heisenberg's uncertainty principle dictates, I cannot know the state of the cat. So long as the cat is within the box, it has no status as either living or dead; indeed, it exists only as a possible either. In reality, of course, the cat is also endowed with consciousness and so does exist in one form or another, but should we rob the cat of its ability to know whether or not it is alive (queror ergo sum...) then the experiment presents a most curious paradox. The only way to know whether or not the cat is alive or dead is to open the box but, until then, the cat must be considered as both.

I only raise this issue to express my opinion that the expression, "Curiousity killed the cat", has more to do with the curiousity of a German scientist than it does with the activities of an inquisitive feline.


At 6:22 PM , Blogger Daniel said...

I hate to be a party pooper (no, not really, I actually quite enjoy it). I guess that with "queroro ergo sum" you were going for "I miaow/whine therefore I am". "Queroro" is not a word. "Queror" is a deponent verb, meaning that it is active in meaning, but passive in form (present passive first person suffix is -or; infinitive passive suffix is -ari; perfect first person suffix is -atus sum). Therefore, "queror ergo sum" would be correct, but loses you the congruency of form with "cogito". It's not easy being green.

At 6:32 PM , Blogger Simon Holloway said...

Ha, thankyou! And you have no idea how long it took me to find an online Latin dictionary that could translate something similar to mew into Latin for me. And then all that wasted time, fumbling in my Latin: An Intensive Course to work out how this verb might have conjugated!

Ah, I knew I should have just asked you. Consider it fixed...

At 2:39 PM , Blogger Flyingcowman said...

A few common misconceptions occur when one tries to relate quantum phenomena to a non-quantum world. These usually result in the description being "slightly wrong", "very wrong", or "fartblastingly turd".

You, my friend, have gotten lucky with this one.

The situation with the cat is similar to that which you describe, however the state of the cat is not "unknown" when it is sealed in the box, nor is it "a possible either". In the quantum world the cat exists in both states *at the same time*. That is, until a quantum particle is measured it exists in *all possible states*, a phenomena known as "quantum superposition". This is a completely different phenomena to uncertainty, and hence makes mincemeat of your closing line. Sorry.

The uncertainty principle broadly states that uncertainty in measurement in inversely proportional with the measured dimension. That is, it is more difficult to measure a smaller object with the same degree of accuracy, proportionally speaking.

Felines aside, quantum superposition combines with another phenomena known as "quantum entanglement" to provide us with an fascinating thought experiment.

(An aside: "entanglement" refers to a process whereby two quantum particles become "married" to each other - that is, one particle takes on the opposite attributes of the other. If the first is negatively charged then the second becomes positively charged, if the first is spinning left then the second spins right, and so on.)

Take a quantum particle in an unknown state, and entangle it with another particle. We do not know what state either of the two particles are in, but we know that they must be the opposite of eachother. Let's now separate the two particles by some distance. Say, a thousand kilometres.

Let us now introduce a *third* quantum particle, that has already been measured and is already is a known state. Let's call it "positive".

Now let's put the third particle next to the first particle and entangle the two. So, what happens? Well, the first particle takes on the opposite characteristics of the third, so it becomes "negative".

The second particle, however, is a thousand kilometres away, but is still entangled with the first particle. Therefore, it becomes "positive".

In case you haven't noticed, we have now just transmitted some information across *any* distance, instantaneously.


(Of course, one could equally argue that we are using a transmission medium that exists in the past, created by the physical movement of the second particle, but magic is just as good. And trying to explain transmitting information in the past is like trying to type with a wild cheetah attached to your testicles.)


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