How do great physicists remember all the equations and formuals?

Physicists don't actually learn equations by heart. They understand how things are related to each other and the equations can be deducted from these relationships.

Most physics education puts too much emphasis on learning equations and laws by heart. I remember how some of my classmates in high school frantically looked for an example in the book that looked like the problem they were trying to solve without even trying to understand what the problem was all about. As a preparation for exams, they meticuloysly tried to memorize the examples so that they could use the same methods in the exam.

Physics is not about memorizing examples, laws or equations. How on earth would we find example solutions for physics problems that are yet to be solved?

Instead of memorizing everything, Physics education should focus on concepts. When you understand the concepts and how they are related to each other, the equations no longer look like complicated combinations of letters and, when you look at them, you will start to recognize patterns and how things affect each other. The solution of a physics problem can even usually be roughly estimated without writing a single equation.

Physics is all about problem solving and that’s also the most important and difficult part. Once you understand a problem, the solution is usually relatively easy to find.

Here’s an example of a chain of thoughts that could be part of solving a high school physics problem:

What area of Physics is the problem about? Mechanics. Is is about forces or movement? Forces as well as the movement they cause. Which forces affect it? Gravity and buoyancy. Are the forces equal? No, gravity is stronger. What does that mean? The object is steadily accelerating to the direction of gravity. Now we know what the problem is about and the solution can be found with a simple calculation.