I don't mean to butt in, but there are a couple things you might like to know.
To say that, because the universe in expanding, an explosion must have taken place, commits a basic logical fallacy called
affirming the consequent. (see
post 231 for an example showing the
Fallacy of Verified Prediction.)
One example of a non-explosion powered 'expansion' is Lunar Recession:
Friction by the tides is slowing the earth's rotation, so the lenght of a day is increasing by 0.002 seconds per century.
This means that the earth is losing
angular momentum. The
law of conservation of angular momentum says that the angular momentum the earth loses must be gained by the moon.
Thus, the moon is slowly receding from the earth at about 12 inches per year.
So we know that redshift indicates motion and would
suggest that the universe is expanding.
(Keep in mind there may be
other things that cause redshift also)
So if the universe is expanding like is popularly thought, that means it needs a driving force.
One possibility is cosmic rotation:
According do Dr. Max Tegmark, of the University of Pennsylvania, who has analyzed
WMAP CMB data and
reported:
"We found something very bizarre; there is some extra, so far unexplained structure in the CMB.
We had expected that the microwave background would be truly isotropic, with no preferred direction in space but that may not be the case."
They had expected to see no pattern at all but what they saw was anything but random.
"The octopole and quadrupole components are arranged in a straight line across the sky, along a kind of cosmic equator. That's weird."
"We don't think this is due to foreground contamination," Dr Tegmark said. "It could be telling us something about the shape of space on the largest scales. We did not expect this and we cannot yet explain it."
This is consistent with a slow general rotation of the matter in the cosmos(with respect to an inertial frame or the 'fabric' of space), because this would produce a quadrupole moment and possibly an octopole moment in the CMB, and would explain the 'cosmic equator'.
So, as you can see, there are competing theories as to why the universe appears to be expanding.
In summing up, we can measure the universe, we cannot mesure the big bang.
Hope that helps.
Ah, thank you, I hadn’t heard of that theory before. I’ll have to read more about it when I have some free time; it sounds interesting.
To clarify myself a bit, however, I wasn’t intending to discount other theories (though I do believe some of my lines betrayed a gross ignorance of the field I’m discussing) - I was just arguing that the Big Bang theory is not inherently contradictory with a belief in God, as some seem to suggest.
In all honesty, I know next to nothing about the Big Bang - my astronomical interests lie in explaining more recent phenomena.