Analyse the following passage and provide appropriate answers for the questions that follow:
Each piece, or part, of the whole of nature is always merely an approximation to the complete truth, or the
complete truth so far as we know it. In fact, everything we know is only some kind of approximation, because
we know that we do not know all the laws as yet. Therefore, things must be learned only to be unlearned again
or, more likely, to be corrected. The principal of science, the de nition, almost, is the following: The test of all
knowledge is experiment. Experiment is the sole judge of scienti c “truth.” But what is the source of
knowledge? Where do the laws that are to be tested come from? Experiment, itself, helps to produce these
laws, in the sense that it gives us hints. But also needed is imagination to create from these laws, in the sense
that it gives us hints. But also needed is imagination to create from these hints the great generalizations – to
guess at the wonderful, simple, but very strange
patterns beneath them all, and then to experiment to check again whether we have made the right guess. This
imagining process is so di cult that there is a division of labour in physics: there are theoretical physicists who
imagine, deduce, and guess at new laws, but do not experiment; and then there are experimental physicists who
experiment, imagine, deduce, and guess.
We said that the laws of nature are approximate: that we rst nd the “wrong” ones, and then we nd the “right”
ones. Now, how can an experiment be “wrong”? First, in a trivial way: the apparatus can be faulty and you did
not notice. But these things are easily xed and checked back and forth. So without snatching at such minor
things, how can the results of an experiment be wrong? Only by being inaccurate. For example, the mass of an
object never seems to change; a spinning top has the same weight as a still one. So a “law” was invented: mass
is constant, independent of speed. That “law” is now found to be incorrect. Mass is found is to increase with
velocity, but appreciable increase requires velocities near that of light. A true law is: if an object moves with a
speed of less than one hundred miles a second the mass is constant to within one part in a million. In some
such approximate form this is a correct law. So in practice one might think that the new law makes no
signi cant difference. Well, yes and no. For ordinary speeds we can certainly forget it and use the simple
constant mass law as a good approximation. But for high speeds we are wrong, and the higher the speed, the
wrong we are. Finally, and most interesting, philosophically we are completely wrong with the approximate law.
Our entire picture of the world has to be altered even though the mass changes only by a little bit. This is a very
peculiar thing about the philosophy, or the ideas, behind the laws. Even a very small effect sometimes requires
profound changes to our ideas
