Magazine 雜志：Physics

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By John Kuti

In the square outside the British Library in London is a sculpture of Sir Isaac Newton – the first man who asked why apples seem always to fall towards the centre of the earth. Maybe they chose it for the spot because it shows a great scientist at work. Actually, it is a critical view of a great scientist, which comes originally from a drawing by William Blake, the romantic poet and artist. Blake wanted to show the limits of science, that it could never understand the beauty and strangeness of nature. The sculpture shows a man crouching down to draw a right-angle on the ground or to measure something he can’t see. Maybe he’s trying to find the direction to the centre of the earth. In Blake’s original you can see strange complicated rocks around Newton that he does not seem interested in studying.

A lot of things in the universe can be measured, but people want to know why they are that size. We know the mass of a quark and the charge on an electron. These are constants. It turns out that these numbers HAVE to be exactly what they are, because if they were different we would not be here. You, me and the physicists, we’re part of the universe. We have to be here to make physics, so physics has to describe a universe where there can be people. Gravity is another problem for physics - because it is everywhere and acts on everything, including space itself. It’s different from other forces like electricity or radiation, because you can’t stop it or turn it off.

Modern physicists still look mostly at things we can’t see. (They think gravity might happen because of something no-one has ever detected called the Higgs boson.) Either very small things in quantum physics or very big things like galaxies. Putting them together is the main problem of modern physics. The universe and space and time described by Einstein and the fuzzy fast-moving little sub-atomic particles and small things that might make them up. If you want to know how the universe began - with a tiny size but very big mass, then you need a theory that fits both together. At the moment, the theory suggests that the things we can see – stars and planets etc. make up only 5% of the universe. The rest is 25% “dark matter” and 70% “dark energy”.

A theory that could explain all that would be a ‘theory of everything” - the real laws of nature. There are already suggestions of what it might be. Scientists think that the laws of nature might be rather simple, even though the real world is full of strange and beautifully complicated things. One suggestion is called “string theory”, the idea is that inside every particle there is some energy that is like the string of a musical instrument – the way it vibrates makes a different sort of particle. At the moment they say there are 18 sorts.

Physicists say that string theory needs extra dimensions. There are other directions where energy can get carried away, and other particles which no one has seen. They try to find them in particle accelerators where protons go round in circles in tunnels getting faster and faster until they reach almost exactly the speed of light. This year the Large Hadron Collider should start work in Switzerland and it is just possible that they will find the Higgs boson, or even the little strings inside it. In 2005, there are also still poets and romantics who would prefer to look for nature’s secrets in other places.