dipper@utastro.UUCP (Debbie Byrd) (01/22/85)
Curved space is a normal feature of our universe. More about it -- after this. January 22 A Ride on Curved Space In the context of our everyday world, it doesn't mean much to say that space is curved. But on the grand scale of the universe, curved space is a fact of nature -- first explained by Albert Einstein in his 1915 theory of general relativity. The idea is that there's more to outer space than just emptiness. Space has a structure of its own, that can change. In this case, space CURVES due to the presence of matter, such as stars. There are plenty of stars -- so curved space is common in the universe. For example, space curves near our own sun. The sun's presence makes it curve. Light rays passing near the sun still travel the shortest distance between two points -- but on curved space, that shortest distance isn't a straight line. Instead, starlight passing near the sun has to ride the curved space around it. Another effect of the curved space near our sun is on the orbit of the planet Mercury. Mercury is very near the sun. It orbits in a region of fairly strongly curved space. This curvature distorts the orbit of Mercury -- so that the planet reaches its nearest point to the sun at a different place in its orbit every time. The change is slight -- but it's large enough to measure. That makes Mercury's orbit a good test of Einstein's theory -- and a good proof that space can be curved. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin