Relativity and Quantum Theory - How to Fit Them Together

Many people take the view that quantum theory is somehow weird or impossible, and why do they do this? Because the theory predicts that sometimes a particle will act like it's a wave, or conversely, a wave will act like a particle. This would seem to be a good reason to think of it as a weird theory. That is, until we look a bit closer at what is going on.

By the way, we should get rid of the unfortunate inference that people sometimes draw from the apparent weirdness of quantum theory: that because it is a bit strange, it is somehow all right to associate it with any weird speculation you feel like having. Before you know it, you have imported all kinds of stuff which properly belongs in the fairground or the travelling show.

Anyway, to summarise the situation of physics, or at least to try in a few words, we are used to the idea of energy travelling from one place to another as a wave form. Anyone who has been to the seaside will know about this. The energy of the sea is transmitted as waves. And what are they waves of? Why, of water, naturally. The water is what scientists call the medium of the waves. The waves cannot exist independently. This is important. To talk of a wave without it being a wave "of" something, is like asking what has happened to my fist when I open up my hand. Or, what is the sound of one hand clapping?

A long time ago, scientists found that light and heat and other forms of energy, like radio waves, exhibited wave-like properties. Or, in other words, properties that were best explained by thinking of them as waves. These forms of energy are called electromagnetic radiation. But they asked, what is the medium of these waves? The waves of the sea wave in water, sound is a wave in air, so...?

They came up with a substance called the "ether", a mysterious substance more subtle even than air, which necessarily had to exist even in a vacuum (to carry light waves across space). They tried for years to detect the ether, without success. But the ether HAD to exist, or what could the waves exist in?

Finally the famous experiment of Michelson and Morley proved beyond any doubt that the ether did not exist. A crisis ensued in the scientific community until Einstein, inspired in part by Michelson-Morley, published his theory of relativity. However, this in some ways made the crisis even worse. At around the same time, the quantum theory was being developed, which showed that electromagnetic radiation consisted of quanta, or bundles of energy, which in a way corresponded to the peaks and troughs of the waves, but instead of being continuous like waves, they were discrete (separate). In fact, in some situations, the behaviour of these quanta of energy was almost like that of particles.

Obviously this was a problem. How could energy be, at the same time, a wave AND a particle?

But it got worse. Some particles of matter were discovered that behaved exactly like energy bundles, and vice versa. Among the many problems this caused was that relativity predicted that matter cannot travel at the speed of light. But if you have a particle that behaves like it is light, you have a contradiction.

I've over-simplified this a lot, of course (because I don't really feel up to writing an entire book tonight) but essentially this is how it was. The two theories, relativity theory and quantum theory, while both true and complete universal theories, nevertheless contradict each other. Einstein, who had worked on the development of both of them, dreamed that one day they would be reconciled in a single Unified Theory, and he hoped to find it, but he never did.

Now to come to my point in writing this. Many people have become confused by experiments like the Double-Slit experiment (in a well-known film) into believing that the observer somehow has an influence on the outcome. This has led many to believe that all you need to do is wish for it, and you will have gold beyond your wildest dreams of avarice. They are encouraged by reports (for example, in this very blog right here) of Schrodinger's unfortunate Cat, where the observer decides the cat's fate.

These people are taking it all too simplistically. It just does not work like this. The true reason for the contradiction is much more to do with the inadequacy of the models, than with the observer choosing what they want to happen. Note well that Schrodinger, when he opens the box, is a necessary part of the experiment, but he does not CAUSE the cat to die or live.

Those who have read Hegel (maybe not many people, I suppose) will perhaps recognise in the opposition of the two theories the workings of the Dialectic, that mysterious truth of metaphysics, which inevitably will lead to the higher Synthesis in the course of time.

In the meantime, it's probably best to be patient, and ever so slightly sceptical, and to allow that, as yet, however it may seem, we actually know very little about the universe.

"It is better to confess you know nothing than to pretend you know everything."