Entangled States

9/2/07 – 9/8/07
C. Zaitz

I’ve been thinking about quantum mechanics lately. QM is a branch of physics that deals with the universe on the scale of the very small. On a daily basis, we don’t enter the realm of quantum mechanics, but more and more, scientists are finding that the properties of the very small scale inform the universe on a very big scale. And it’s a quite different universe on the small scale.

On the scale of the tiny, basic laws of “classical” physics break down. We are used to measuring things and describing their positions with numbers. In the realm of atoms, measuring things becomes impossible. You may have heard of Heisenberg’s Uncertainty Principle, the idea that you cannot know both the position and the momentum of an electron orbiting the nucleus of an atom. You can know where an electron is likely to be, but you can’t pinpoint it. The act of doing so would destroy the information you were trying to get. Once you “stop” the electron to study it, you have changed its momentum. And you cannot get around this fact. The measuring and the measured thing are entangled, you cannot separate them. We can intuit that perhaps more easily than other aspects of QM. In art, we say that “negative space” is as important as the object in space. There is a direct and entangled relationship between the object and the space around it. Change the object, and you automatically change the space surrounding it.

It turns out that objects, rather than just being objects, are better described as a series of relationships. You might not be able to know exactly where one particle is, but if it is entangled with another particle having an opposite position, you can know that whatever you do to one particle will always affect its entangled particle. So if one egg is sunny side up and its entangled partner is sunny side down, you can flip one egg and automatically and always flip the other too. This is called “entangled states.”

In quantum mechanics, we have to give up absolutes and accept probabilities. Perhaps that’s why we never notice quantum mechanics in our daily lives. QM says there is a real possibility that all of the atoms in your body could pass right through the atoms of a wall, allowing you to walk right though it. Does that mean Kung-Fu masters can really walk through walls? No, because on the scale of a human being, the probability of that happening is incredibly small, almost non-existent. But on the scale of the atom, it can happen. In fact it does happen, and furthermore, we rely on it happening. It’s called “quantum tunneling” and it’s the basis for our modern electronics and microchips.

Science and philosophy come together in quantum mechanics. We often say that the age of determinism in science, where A causes B through a direct line of events, has been replaced with the age of probability. Einstein hated this idea. His aversion to it shows up in his famous quote, “God does not play dice with the Universe.” Even today many people reject the underlying philosophical ramifications of QM while using its principles and products in every day life. But I find the QM idea of probabilities, relationships and entangled states to be an active and connecting philosophy. And we’ve only begun to explore it.

Until next week, my friends, enjoy the view