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The Unreasonable Effectiveness of Mathematics
Mathematics, invented by contemplating abstractions, turns out to describe the physical world with uncanny precision.
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The Holographic Principle
A startling idea suggests that everything within a region of space can be described by information on its boundary.
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Wave-Particle Duality
Light and matter behave sometimes as waves, spreading and interfering, and sometimes as particles, arriving in discrete lumps.
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The Uncertainty Principle: Limits of Simultaneous Knowledge
Certain pairs of properties cannot both be known sharply at once.
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Decoherence: Why the Quantum World Looks Classical
If matter is quantum, why does the everyday world appear solid and definite, never blurred across possibilities? Part of the answer is decoherence, the leaking of quantum coherence into the environment.
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Reversibility and Its Limits
At the microscopic level, physics runs equally well forward and backward; the film of colliding particles looks lawful in reverse.
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Landauer’s Principle: The Energy Cost of Forgetting
Erasing a bit of information is not free.
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The Second Law: Why Time Has a Direction
Among physical laws one stands apart for caring about direction.
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Entropy and the Arrow of Time
The laws of physics look the same run forward or backward, yet time plainly flows one way.
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Conservation Laws and What They Forbid
Some quantities never change, whatever else does.