My favorite Physics Ideas 101
written by Laramie:
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The fact that all bodies attract each other, and the strength of the attraction decreases by the square of their distances apart, is called gravity.
The Second Law of Thermodynamics says that heat travels from hot to cold bodies, but not the other way around.
If it is so cold that the atoms of a substance stop moving, that's absolute zero temperature. But it can never be observed, because no thermometer could measure it.
Chaos Theory says that tiny changes in circumstances in a situation can result in far reaching changes in the situation.
Passing white light through a prism splits the light into the hues of the rainbow, and that's Newton's theory of color.
The Doppler effect says that sound waves coming towards you are squashed together and result in a higher frequency and so a higher pitched sound, whereas sound waves moving away from you are lengthened and result in a lower pitched sound. (The same principle shows up in light waves.)
Heisenberg argued that the very act of measuring a particle changes its location and motion, therefore you can never be certain of a particles location or what its motion is, at any given time. This is the Uncertainty Principle of Heisenberg.
Grounded observers watching objects approach light speed, say watches on a speeding airplane, would see that the watches on the plane slowed down, as compared to their own watches on the ground. And the observers on the plane would see the watches on the ground speed up. This is part of Einstein's Special Theory of Relativity.
A Black Hole is an object in space that is so massive and dense that its gravity is so powerful that nothing can escape its attraction, not even light.
Hubble's Law states that all galaxies are receding from every other galaxy, and the farther away they are from that other galaxy, the faster they are moving away.
The Big Bang was the birth of the universe, when all space, time and matter was contained in a single point. When the point exploded, everything that exists was formed.
Ninety per cent of the matter in the Universe does not glow, but is dark. We cannot see it, we see only the effects it has on other objects. This is called Dark Matter.
Fermi's paradox wonders why, given the billions of stars and planets in the Universe, we have not yet been contacted by any other alien civilization.
The Anthropic principle states that the Universe is what it is because if it were any different we would not be here to observe it. The Chaos Theory in action.
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