Big Bang Theory

Although the big bang model has done a good job of explaining what is seen in the Universe, there are still many unanswered questions. There is still disagreement about the exact value of the Hubble constant by approximately a factor of two. The Hubble Space Telescope is making observations similar to those made by Edwin Hubble in order to try to measure this quantity more accurately. Preliminary results have been announced, but it will be some time before a value can be accurately determined. These measurements are very difficult to make, since they are at the limits of the telescope's ability to observe.

Another open question is how galaxies actually formed from what was very close to a uniform, homogeneous medium in the early universe. From the uniformity of the microwave background radiation, it is known that this uniformity was better than one part in a thousand. Just by looking at the sky, however, a great deal of structure in the Universe is seen up to very large-size scales of clusters of galaxies and beyond. There must have been some type of clumping which occurred to start the process (with gravity helping the process along), but what started it? Physicists are seeking the answer in quantum mechanics, the science of very small events. The answer resides there because at the moment of the big bang, the Universe was subatomic in size.