Changes

Until the beginning of the twentieth century, the central belief system in [[astronomy]] took its cue from the [[uniformitarianism]] of [[Charles Lyell]] in [[geology]]. Paraphrased for astronomy, this kind of uniformitarianism would say that the same processes we observe operating in space have always operated in the past. And furthermore, classic uniformitarianism says that this past had no beginning.

Until the beginning of the twentieth century, the central belief system in [[astronomy]] took its cue from the [[uniformitarianism]] of [[Charles Lyell]] in [[geology]]. Paraphrased for astronomy, this kind of uniformitarianism would say that the same processes we observe operating in space have always operated in the past. And furthermore, classic uniformitarianism says that this past had no beginning.

Later observations became impossible to reconcile with "no beginning." So uniformitarianism now says that the universe had a beginning but need not have an end. The usual model expressing this thought is the [{Big Bang]]. It called for an explosion, not merely of matter, but of space itself.

Later observations became impossible to reconcile with "no beginning." So uniformitarianism now says that the universe had a beginning but need not have an end. The usual model expressing this thought is the [[Big Bang]]. It called for an explosion, not merely of matter, but of space itself.

But Big Bang theorists have a problem of their own: in any explosion, uniformity of [[temperature]] cannot be assured. For temperature to equilibrate, radiation has to pass from one part to another. Now if the temperature of space is uniform (and it might be), how did this come about if equilibrating radiation could not propagate itself any faster than the [[speed of light]]?

But Big Bang theorists have a problem of their own: in any explosion, uniformity of [[temperature]] cannot be assured. For temperature to equilibrate, radiation has to pass from one part to another. Now if the temperature of space is uniform (and it might be), how did this come about if equilibrating radiation could not propagate itself any faster than the [[speed of light]]?