In physics you have a bit of everything: you need to be good at solving puzzles, but you also need to see the big picture, to separate important from unimportant things, to quickly understand new materials and quickly see the essence of a paper.

If you really want to contribute to our theoretical understanding of physical laws — and it is an exciting experience if you succeed! — there are many things you need to know. First of all, be serious about it!

Therefore psychologically we must keep all the theories in our heads, and every theoretical physicist who is any good knows six or seven different theoretical representations for exactly the same physics.

What do we mean by “understanding” something? We can imagine that this complicated array of moving things which constitutes “the world” is something like a great chess game being played by the gods, and we are observers of the game. We do not know what the rules of the game are; all we are allowed to do is to watch the playing. Of course, if we watch long enough, we may eventually catch on to a few of the rules. The rules of the game are what we mean by fundamental physics. 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 does. So it is in nature, only much more so.

In fact the total amount that a physicist knows is very little. He has only to remember the rules to get him from one place to another and he is all right...

We cannot do it in this way for two reasons. First, we do not yet know all the basic laws: there is an expanding frontier of ignorance. Second, the correct statement of the laws of physics involves some very unfamiliar ideas which require advanced mathematics for their description.

So we have these wide principles which sweep across all the different laws, and if one takes too seriously its derivations, and feels that this is only valid because this [assumed more fundamental principle] is valid, you cannot understand the interconnections of the different branches of physics. Some day, when physics is complete, then maybe with this kind of argument we'll know all the laws, then we can start with some axioms (and no doubt somebody will figure out a particular way of doing it) and then all the deductions will be made. But while we don't know all the laws, we can use some to make guesses at theorems which extend beyond the proof.

Physics training is a good framework for reasoning," explains Musk. "It forces you to boil things down to their most fundamental truths and then connect those truths in a way that lets you understand reality. This gives you a way to attack the counterintuitive, a way of figuring out things that aren't obvious. When you're trying to create a new product or service, I think it's critical to use this framework for reasoning. It takes a lot of mental energy, but it's still the right way to do it.

To adapt to the reality of scale, meanwhile, Musk employs a number of other strategies. We'll start with first principles, which is a lesson he borrowed from physics. "Physics training is a good framework for reasoning," explains Musk. "It forces you to boil things down to their most fundamental truths and then connect those truths in a way that lets you understand reality. This gives you a way to attack the counterintuitive, a way of figuring out things that aren't obvious. When you're trying to create a new product or service, I think it's critical to use this framework for reasoning. It takes a lot of mental energy, but it's still the right way to do it."

Why do you want to come into physics? All is done and understood.

Before a science can develop principles, it must possess concepts. Before a law of gravitation could be formulated, it was necessary to have the notions of “acceleration” and “weight.”

You would have to ask a physicist really but I think understanding fundamental problems in physics is very important because they are part of our culture. You just never know what is going to come from it. If you had told Isaac Newton about spaceships and satellites that arise from his laws of gravity, it would have been science fiction to him.

Most people who haven't been trained in physics probably think of what physicists do as a question of incredibly complicated calculations, but that's not really the essence of it. The essence of it is that physics is about concepts, wanting to understand the concepts, the principles by which the world works.

Every physicist (naturally, this equally applies to other specialities, but I restrict myself to physicists for definitiveness) should simultaneously know, apart from theoretical physics, a wealth of facts from different branches of physics and be familiar with the newest notable accomplishments.