Pirx un[blog]ged

Mike is reading four blogs. This is none of them.

Sorry for being symmetric

Today I watched two little boys in the age of six or seven playing on a small puddle. They were very excited about throwing pebbles into this puddle. The water splashed and they giggled. The boys had obviously much fun. Quickly the pebbles get bigger and after all one boy raised a really big stone. The other boy positioned itself on the opposite side in order to see what will happen. And one thing led to another. The water splashed against the surprised boy and the other was not less surprised. He yelled: "Sorry" and something like "We can do better" already looking for the next big stone. An then they did better and stood again around the puddle, one boy opposite the other but this time turned by 90 degrees. You can guess what happened - exactly the same as before.

This little story may sound funny but still gives the two young boys a glimpse of a basic characteristic of nature laws: symmetry.

Symmetry means that - in simple words - we can do to something and leaves everything unchanged in its effects. I've always found this very fascinating. It's something like a law about physical laws. A deeper insight the operation of the physical world. There are several types of symmetry and scientists discovered e.g. that every conservation law is related to a symmetry. So isometry of time is correlated to conservation of energy.

Sometimes such a symmetry is broken. This is mostly the case after a significant increase of energy. And to our astonishment this is another physical law. Let's take our example from above. If the boy would throw the stone with a multiple of energy, the water would instantly evaporate and the other boy would stay dry. OK, this is just a not so good example, but I'm sure you get the point. Physics determines our lives.


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