A Brief History of Time

重要なポイント

• 時空は織り合わされており、質量がシーツの上の重りのようにそれを歪める
• 宇宙は膨張している。つまり超高温・超高密度の状態から始まったのだ
• 極大の世界は相対論が、極小の世界は量子力学が支配している
• ブラックホールは完全な黒ではない。放射を放ち、少しずつ蒸発する
• 無秩序さが増すからこそ時間は一方向に進み、人は過去を記憶できる

このbitの内容

1. わかりやすい言葉で語る宇宙

   A scientist gives a public lecture on astronomy and an elderly listener insists the world rests on the back of a giant turtle. Asked what the turtle stands on, she replies that it is turtles all the way down.

2. Space and time bend

   For centuries, people thought of time as a universal clock ticking the same everywhere. Einstein overturned that.

3. 遠ざかり続ける宇宙

   In the 1920s, Edwin Hubble noticed that distant galaxies are moving away from us, and the farther away they are, the faster they recede. This is what an expanding universe looks like from the inside.

4. 極小の世界の奇妙なルール

   Relativity governs stars and galaxies, but a different set of rules runs the world of atoms. Quantum mechanics says that you cannot know both the exact position and exact speed of a particle at once; nature has a built-in fuzziness.

5. Black holes and the arrow of time

   A black hole forms when a massive star collapses so far that not even light can escape its gravity. For decades it was assumed nothing could ever come out.

6. 実践に移す

   This week, step outside on a clear night and pick one star, remembering that the light entering your eye left it years or centuries ago, so you are looking at the past. Watch a short explainer on how GPS satellites correct for relativity, and you will see Einstein's ideas at work in your phone.