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1.2 Quantum Mechanics Summary
summary
- The goal of physics is to observe the universe and figure out its governing rules.
- By understanding nature, we will be able to predict future conditions of the universe.
- There are two known types of rules for understanding the universe: Classical Physics and Quantum Physics.
- Classical physics
- Mathematical representation of an object’s current position and velocity
- Newton’s laws provide rules for figuring out the object’s later position and velocity.
- Classical rules are only approximations.
- Quantum physics
- At atomic and subatomic scales (and sometimes macroscopic scales), we need a more complete theory.
- In this theory, objects can be in quantum superpositions, which according to Professor Van Raamsdonk, are states where objects lack any definite positions until we observe them.
- The wavefunction for an object describes the probabilities of all the states that comprise the superposition, that is, the probability that any one of those states will actually be observed.
- The Schrödinger equation is the rule for determining how an object’s (most likely superposed) state evolves over time.
- Richard Feynman and others determined quantum versions of most physical laws, for example, quantum electrodynamics.
- Quantum electrodynamics, plus the weak and strong forces, give rise to the standard model of physics.
- Gravity has not yet fully been incorporated into quantum mechanics.