Wednesday, July 18, 2007

Determinism

Science (especially physics) has plenty in common with philosophy. This may seem strange, because in school they seem radically different from each other: science involves the demonstration of certain rigid facts and truths that are immutable, whereas philosophy involves thinking about life, and is fraught with grey areas.

But the perception that science is about facts and truths is a dangerous one. In fact, as scientists, we know of nothing that is a fact or a truth. You probably already know this: no inductive statement can be made in the certainty that it is absolutely and totally correct. What are inductive statements? They are general conclusions that are believed to be true, true made after some observations. For example, you've seen the Sun rise in the east your whole life, and so you claim that "the Sun always rises in the east". That is a conclusion you have arrived at, because you've seen it happen again and again, but of course, that is no guarantee that the same will happen tomorrow. Of course, you could say, "yesterday, the Sun rose in the east," but science has no use for these statements: they are mere observations, which are distinct from conclusions.

So as you can see, whatever you've been taught, e.g. the angle of incidence and the angle of reflection are always equal in the reflection of light, are not facts. They are merely statements that have been tested repeatedly, possibly millions of times, and have not once been found to be wrong.

What has been said so far is just a small glimpse into the philosophy of science, and unfortunately pretty much all I'm confident enough to speak on about this huge subject. If you look at the two subjects of physics and philosophy, you can see why they are so intertwined: one is the scientific study of the universe, while the other is thinking about the true nature of the universe. Actually, the subject matter at hand is pretty much the same in both subjects! Just that the approach is different.

So I leave you with a philosophical tidbit to ponder over, and, in accordance with your syllabus, it's related to Newton's Laws. I hope that as you are studying Newton's Laws, you will realise that these laws, together with Newton's Law of Gravitation, are meant to describe any kind of motion, whether it's normal motion down here on Earth, or the motion of stars and galaxies. They encompass everything in the universe. Why things stay still, why things move at constant velocity, why things have a change in their velocity, and how do we know how much it changes by, how objects interact with each other, these are just some of the questions answered by Newton's Laws.

Imagine that we knew what every single particle in the universe was doing at this exact moment, where every particle was and how it was moving. Since we know how each and every particle is going to move (since they move according to Newton's Laws), if we fed all of this information into a gigantic supercomputer, wouldn't the computer be able to work out the exact future of each and every particle? In other words, predicting the future is possible if we knew precisely what every single particle is doing in the whole universe.

Now, think about what implications this has on human beings. Aren't we composed of particles ourselves, that undoubtedly obey Newton's Laws? If there was someone somewhere out there running a supercomputer that really did know the exact position and motion of every single particle in the universe, wouldn't he be able to look into our futures? Doesn't that mean that our futures are already cast in stone?

With the advent of Newton's Laws, many people began to believe that the universe is deterministic: the idea that there is only one possible future to this universe. This idea posed a great challenge to European thought, which was still closely associated with Christian beliefs in the 17th and 18th centuries.

Nowadays, with the advent of quantum theory and the theory of relativity, which in effect are more accurate ways of looking at the universe as compared to Newton's Laws, the universe is commonly regarded as being indeterministic, although much debate still rages on over what the horribly complicated math of quantum mechanics actually suggests. I leave you to read about the Heisenberg Uncertainty Principle and the many interpretations of quantum mechanics.

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