A person or piece of equipment that measures something in physics. Frequently, we speak of an observer measuring time or a distance in a particular place.

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A particular point with respect to which positions are measured.  For example, positions on the Earth are frequently measured relative to the point on the Equator which is due South of Greenwich, England.  In GPS coordinates, that point is given as 0,0 (its latitude is 0, and its longitude is 0).  Or we might say something like “10 miles southeast of town hall.”  In that case, town hall would be the origin.

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Four Areas of Science


Go, wond'rous creature!
Mount where Science guides,
Go, measure earth, weigh air,
    and state the tides;
Instruct the planets in
    what orbs to run,
Correct old Time,
    and regulate the Sun.

Alexander Pope's
An Essay on Man

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About SXS

The SXS project is a collaborative research effort involving multiple institutions. Our goal is the simulation of black holes and other extreme spacetimes to gain a better understanding of Relativity, and the physics of exotic objects in the distant cosmos.

The SXS project is supported by Canada Research Chairs, CFI, CIfAR, Compute Canada, Max Planck Society, NASA, NSERC, the NSF, Ontario MEDI, the Sherman Fairchild Foundation, and XSEDE.

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