Expansion, Not a “Big Bang” Explosion
Lemaître started the idea that the universe began with an explosion. He was also wrong about that. The universe did not explode. It expanded. Explosions disrupt existing order, but the expansion of the universe was orderly. Astronomers have photographed the universe as it was after a great deal of expansion. Considerable order is still clearly visible, particularly the order of uniformity or homogeneity. The first light has the same temperature everywhere to within a few tens of microkelvins.
Random action makes some parameters regular through the statistical “law of large numbers.” This means that random processes produce very regular averages when there are many particles involved.
Random collisions of air molecules keep the air pressure nearly constant in our bedrooms. Who could sleep fearing that the air might suddenly collapse into a thin layer on the floor and stay there for 10 minutes? Happily the probability of that happening is so small we may as well just say it is impossible.
Random action produces the characteristics of thermal light, light from incandescent sources. The first light is the most perfectly thermal light we have ever detected.
For these reasons it is not correct to say that the universe began with a “big bang.” P. J. E. Peebles explains what is wrong with this idea.
Random action makes some parameters regular through the statistical “law of large numbers.” This means that random processes produce very regular averages when there are many particles involved.
Random collisions of air molecules keep the air pressure nearly constant in our bedrooms. Who could sleep fearing that the air might suddenly collapse into a thin layer on the floor and stay there for 10 minutes? Happily the probability of that happening is so small we may as well just say it is impossible.
Random action produces the characteristics of thermal light, light from incandescent sources. The first light is the most perfectly thermal light we have ever detected.
For these reasons it is not correct to say that the universe began with a “big bang.” P. J. E. Peebles explains what is wrong with this idea.
The familiar name for this picture, the “big bang” cosmological model, is unfortunate because it suggests we are identifying an event that triggered the expansion of the universe, and it may also suggest the event was an explosion localized in space. Both are wrong. The universe we observe is inferred to be close to homogeneous, with no evidence for a preferred center that might have been the site of an explosion. The standard cosmological picture deals with the universe as it is now and as we can trace its evolution back in time through an interlocking network of observation and theory. We have evidence from the theory of the origin of the light elements that the standard model successfully describes the evolution back to a time when the mean distance between conserved particles was some ten orders of magnitude smaller than it is now. If it is found that still earlier epochs left evidence that can be analyzed and used to test our ideas, then that may be incorporated in the standard model or some extension of it. If there were an instant, at a “big bang,” when our universe started expanding, it is not in the cosmology as now accepted, because no one has thought of a way to adduce objective physical evidence that such an event really happened.[i]
[i] Peebles, P. J. E., Principles of Physical Cosmology (Princeton, New Jersey: Princeton University Press, 1993), p. 6.
Later Peebles suggests that instead of saying “the Big Bang” we should substitute the name “the standard expanding world picture.” The Bible puts the idea more simply, stating that God put expansion in the heavens.