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Science (Lat. scientia, from scire, "to know") is wonder about nature - why is it so? Like philosophy, science thrives on questions - but also has the means to answer them, if they concern the state and behaviour of the physical world. Science is the systematic study of the properties of the physical world, by means of repeatable experiments and measurements, and the development of objective theories describing these activities, and predicting verifiable features that could be also tested by experiment. Statements in science must be precise and meaningful, such that they can be tested by experiments or observations by other people, with the same results.

What is Science?

Its a simple enough question, but one which can stir either heated debate between scientists, or provoke bored indifference. They may not know how to define it - but they know it when they do it. So, a first rough definition - a working hypothesis - could be, "Science is what scientists do". Those who have studied scientists and what they do, generally conclude that science is distinguished from other human activities, such as the arts and humanities, by the clear application of scientific method. In a nutshell, we can describe it as an idealised sequence of steps:

1. Observation. Noticing an interesting phenomenon or property.
2. Hypothesis. Formulating a possible explanation for it.
3. Experiment. Creating conditions to test the hypothesis.
4. Prediction. Succesful hypotheses should also predict new phenomena.
5. Analysis. Melding successful hypotheses into a more general framework of other theories and laws.

The central foundation of the scientific method is that all claims to 'explanation' must be testable by repeatable experiments. That means that nobody will just take your word for it, if you claim to know why something is so; they must be able to perform experiments that test your hypothesis, and try to prove it wrong. A key feature of scientific method is that hypotheses, theories, and laws - any statement purporting to describe or 'explain' the world - must be falsifiable. There must be a way, in principle, to be able try to prove the statement to be false. That doesn't mean that it will be proven false, only that there are reasonable ways to test it.

If I ask you why the Moon doesn't fall down to the Earth, and you tell me that it's because its held up by an undetectable lift (elevator) shaft built by ancient extraterrestrials, then you have given me a pseudo-scientific theory. None of my scientific measuring devices will ever be capable of detecting this purported lift shaft, so I cannot even try to prove you wrong. Your theory is unfalsifiable.

However, if you claim that the Moon stays aloft due to the balance between the centrifugal force due to orbital motion, and the mutual gravitational attraction between Moon and Earth; and you have some formulae for these forces, derived from your hypothesis, then we can check your formulae against the known facts, and try out your model on other similar cases, such as the Earth orbiting the Sun. Before we do, however, its definitely conceivable that the formulae will fail. We have something to work with, instead of nothing that can ever be disproven.

Einstein - Imagination Buy this Poster at AllPosters.com

The Limits of Science

There once was a famous scientist who claimed that, given all the data about the Universe - e.g. the positions and motions of all the waves and particles in it - he could compute the evolution of the Universe if he had a powerful enough computer. This was the mechanistic or clockwork view of the Universe, and it is one that is not held today, for at least the following reasons:

• According to Heisenberg's Uncertainty Principle, the more accurately you measure a quantity such as the position of a (sub-atomic) particle, the less accurately you can measure other quantities, such as velocity. This isn't simply a technological limitation - its a basic feature of the quantum mechanical theory of matter, which has been verified to enormous accuracy and is probably the most succesful scientific theory ever - in spite of its strange counter-intuitive foundations.
• According to chaos theory, non-linear systems (which account for most complex physical systems) exhibit instabilities which can't be accurately computed, very far ahead in time.
• We don't know that all the phenomena in the Universe are amenable to the application of scientific method. Can you measure the quality of a Beethoven sonata, or the joy of holding your newborn child?

Science doesn't claim the whole of human experience as its domain.

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