Astronomy Fundamentals

Time, Waves, and Particles

How do space and time relate to one another?

The three dimensions of space and one dimension of time are linked together as a four-dimensional fabric called spacetime. In the early twentieth century scientists such as Alexander Friedmann (1888–1925), Howard Percy Robertson (1903–1961), and Arthur Geoffrey Walker (1909–2001) presented the modern mathematical representation of how the four dimensions are linked together; this equation is called the metric of the universe.


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