How do I learn about physics?

How much physics can one person learn in a lifetime?

• If we assume that the person is an average physicist who does no research. Instead, he tries to study every topic in physics and reads every paper ever published. Would he be able to learn every single relationship that the physics community has explored? Would he even be able to remember them all and use them effectively? For the older "Quorans" answering this question, how much physics knowledge have you retained?

• Answer:

  If you spent 18 hours a day everyday for your entire life from puberty until death (let's say 14 until 84... a solid 70 years), which is incredibly unrealistic in itself anyway, you would not be able to intimately know, understand and work with every aspect of physics, nor would you be able to read ALL of the literature. I have no doubt that any person who does even close to that extent of studying will probably know a bit about everything (in terms of general fields), but not everything about everything. This is just the way life works, you cannot possibly read and comprehend fast enough to keep up with science (let alone read all the previous literature too). This is why you don't see cosmologists telling a colleague who specializes in a specific area of string theory what to do, because they likely don't know much about string theory, let alone all the little discrete details. So, while studying hard can allow you to be an expert in some areas or knowledgable in many, you won't be mastering everything regardless of who you are or how hard you try (barring you somehow integrate some breakthrough AI with your brain, in which case, where's mine?).