The Character of Physical Law: 8 key ideas
The core ideas of The Character of Physical Law, each in under a minute, written in our own words. Want the full depth? Get the book.
- IDEA 1 OF 8
Laws share common features
Feynman, in lectures given at Cornell, looks at what physical laws have in common rather than at any single law.
He wants to show the patterns and character that run through all of physics.
- IDEA 2 OF 8
Gravity shows how laws work
Feynman uses the law of gravitation as his main example.
It is simple to state, yet it explains tides, planets and galaxies, and it was tested and refined over centuries.
- IDEA 3 OF 8
Nature speaks in mathematics
Feynman argues that the laws of physics are best expressed in mathematics.
He suggests that people who do not know mathematics miss some of the deepest beauty of nature. He tries to share that beauty in words.
- IDEA 4 OF 8
Some things never change
Feynman explains conservation laws, such as the conservation of energy, charge and momentum.
These principles say certain totals stay the same no matter what happens. They let physicists make predictions without knowing every detail.
- IDEA 5 OF 8
Symmetry shapes physical laws
Feynman describes symmetries, ways a situation can be changed without changing the laws.
For example, the laws are the same here and on a distant planet, and today and tomorrow.
- IDEA 6 OF 8
Past and future feel different
Feynman explores why the basic laws seem to work the same forwards and backwards in time, while everyday events clearly do not.
He links this to the growth of disorder.
- IDEA 7 OF 8
Nature includes uncertainty
Feynman explains that quantum mechanics makes some events impossible to predict exactly, only their probabilities.
He presents this as how nature truly is, not a weakness of our tools. This idea troubled many scientists.
- IDEA 8 OF 8
New laws begin as guesses
Feynman describes how physicists find new laws: by guessing, working out what the guess predicts and then checking those predictions against experiments.
However elegant an idea is, he insists, experiments have the final word.
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