What do I advise? Forget it all. Don't be afraid. Do what you get the most pleasure from. Is it to build a cloud chamber? Then go on doing things lik… - Richard Feynman

The worthwhile problems are the ones you can really solve or help solve, the ones you can really contribute something to. … No problem is too small or too trivial if we can really do something about it. <p>You say you are a nameless man. You are not to your wife and to your child. You will not long remain so to your immediate colleagues if you can answer their simple questions when they come into your office. You are not nameless to me. Do not remain nameless to yourself — it is too sad a way to be. Know your place in the world and evaluate yourself fairly, not in terms of the naïve ideals of your own youth, nor in terms of what you erroneously imagine your teacher's ideals are.

It is important to realize that in physics today, we have no knowledge what energy is. We do not have a picture that energy comes in little blobs of a definite amount. It is not that way.

"What is this "zero mass"? The masses given here are the masses of the
particles at rest. The fact that a particle has zero mass means, in a way, that it
cannot be at rest. A photon is never at rest, it is always moving at 186,000 miles a
second."