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What you will learn in Modern Physics: Relativity

1. The Speed That Would Not Change
One measurement that refused to behave, two postulates that explain it, and a clock that shows what they cost.
2. Now Is Not a Universal Thing
Two flashes, one train, and two observers who disagree about whether they happened together — after allowing for the travel time.
3. Moving Clocks Run Slow
How much slower, why nobody noticed for two hundred years, and the particle that reaches the ground only because it is true.
4. Shorter Along the Way You Are Going
The same disagreement about now, seen from the side — and why only one of an object's three dimensions is affected.
5. Mass Is Energy Standing Still
A gram of anything is ninety terajoules. What changes between a candle and a bomb is not the physics but the fraction.
6. The Happiest Thought
Two sealed cabins, every experiment you can think of, and no way to tell gravity from acceleration.
7. Gravity Is the Shape of Spacetime
An orbit that will not close, one extra term in the equation, and the forty-three arcseconds that made the theory credible.
8. Where You Can Check It
A satellite constellation that would fail within minutes without both halves of the theory, and starlight that arrives from the wrong place.

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1. The Speed That Would Not Change
One measurement that refused to behave, two postulates that explain it, and a clock that shows what they cost.
2. Now Is Not a Universal Thing
Two flashes, one train, and two observers who disagree about whether they happened together — after allowing for the travel time.
3. Moving Clocks Run Slow
How much slower, why nobody noticed for two hundred years, and the particle that reaches the ground only because it is true.
4. Shorter Along the Way You Are Going
The same disagreement about now, seen from the side — and why only one of an object's three dimensions is affected.
5. Mass Is Energy Standing Still
A gram of anything is ninety terajoules. What changes between a candle and a bomb is not the physics but the fraction.
6. The Happiest Thought
Two sealed cabins, every experiment you can think of, and no way to tell gravity from acceleration.
7. Gravity Is the Shape of Spacetime
An orbit that will not close, one extra term in the equation, and the forty-three arcseconds that made the theory credible.
8. Where You Can Check It
A satellite constellation that would fail within minutes without both halves of the theory, and starlight that arrives from the wrong place.