Six Easy Pieces

First, there may be situations where nature has arranged, or we arrange nature, to be simple and to have so few parts that we can predict exactly what will happen, and thus we can check how our rules work.

In recent years we have discovered that all mass is made of tiny particles and that there are several kinds of interactions, such as nuclear forces, etc. None of these nuclear or electrical forces has yet been found to explain gravitation.

How can we tell whether the rules which we “guess” at are really right if we cannot analyze the game very well?

No machinery has ever been invented that “explains” gravity without also predicting some other phenomenon that does not exist.

This is the only way in which the mass of the earth can be determined.

How do we know that there are atoms? By one of the tricks mentioned earlier: we make the hypothesis that there are atoms, and one after the other results come out the way we predict, as they ought to if things are made of atoms.

to put together things which at first sight look different, with the hope that we may be able to reduce the number of different things and thereby understand them better.

If we know the rules, we consider that we “understand” the world.

Even if we knew every rule, however, we might not be able to understand why a particular move is made in the game, merely because it is too complicated and our minds are limited. If you play chess you must know that it is easy to learn all the rules, and yet it is often very hard to select the best move or to understand why a player moves as he doe