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Quantum mechanics
Quantum mechanics is a fundamental branch of theoretical physics that replaces Newtonian mechanics and classical electromagnetism at the atomic and subatomic levels. It is the underlying framework of ... > more -
Special relativity
Special relativity inter-relates space and time in such a way that the speed of light is constant, and the theory leads to situations where two observers can disagree over time intervals and ... > more -
Carl Sagan
Dr Carl Edward Sagan (November 9, 1934 - December 20, 1996) was an American astronomer, astrobiologist and highly successful science popularizer. He pioneered exobiology and promoted the Search for ... > more -
Barred spiral galaxy
A barred spiral galaxy is a spiral galaxy with a band of bright stars emerging from the center and running across the middle of the ... > more -
Open cluster
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud, and are still loosely gravitationally bound to each other. In contrast, globular ... > more -
Definition of planet
The definition of "planet" has for some time been the subject of intense debate. Although the word dates back thousands of years, no officially decreed scientific definition of "planet" existed ... > more
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