Expert: Jayendra Upadhye - 5/11/2005

Question
Was there a Big Bang Singularity at the beginning of time? I there is how can we prove it? Will the Universe one day collapse back and thus enable time to go back enough for human to view the Singulairy (if there was one)?

Answer
Hi Roger,
1  - Yes! The evidence so far suggests strongly that there was an event about 15 billion years ago that could be called a bang.
The Cosmic Background Radiation is the Echo of the Big Bang.
It is the original radiation that emerged with time and space, and has now cooled to about 3 deg K.

2 - This same radiation is a "fossil" proof of the bang. It corresponds to a black body radiating at a temperature of 3 deg kelvin.

3 - Depending on the possibility of the existence of "dark matter" indirectly detected so far in the spiral planes of spiral galaxies, and the possiblity of the nuetrino having a slight (no matter how trifling) mass, the universe may just have enough mass to halt its own expansion, and in time, begin the inexorable collapse.

4 - But time only flows "forward" in our universe, just as entropy can only "always increase". In such a collapsing universe, time will still be flowing forward so one may never "revisit" past times.

However, as the dimesions of the universe approach very small size, one may "revisit" the same conditions that existed at the time of the bang. The cheif difference being the presence of heavy elements which were totally absent immediately after the bang. These came into being only after the first stars started their celestial kitchens that cooked up the carbon in our bodies, the oxygen we breathe, the salt we eat and the water we drink!

(Indeed many salts and water are created immediately in the aftermath of the supernova after their "recombination" temperatures have been crossed by the cooling debri of the explosion.)

We are made of star stuff!
Jayen