Universe

A diagram of how the universe expands

In physical cosmology the universe is commonly defined as everything that exists. This consists of all physical matter and energy, the planets, stars, galaxies, and the contents of intergalactic space.

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Albert Einstein

Albert Einstein

(14 March 1879 – 18 April 1955) was a German-born theoretical physicist who discovered the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics.He received the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect".The latter was pivotal in establishing quantum theory within physics...

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Black Hole

A black hole is a region of space from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is an undetectable surface called an event horizon that marks the point of no return. It is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics.Quantum mechanics predicts that black holes emit radiation like a black body with a finite temperature. This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater. Read more...

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The Crab Nebula

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