Evidence for the Big Bang
The Universe is made from hundreds of billions of galaxies which are collections of hundreds of billions of stars. When astronomers look at the galaxies they can tell if they are moving by looking at their red shift. They know the red shift technique works because it has been verified and calibrated against other techniques available.
The important finding is that almost every galaxy is moving away from us and the more distant the galaxy the faster it is moving. The consequence of this is that the Universe must be expanding (if you can't see why have a look on the Internet - there are plenty of good explanations).
If the Universe is expanding there are a couple of possibilities. First, the Universe has always expanded which means it was zero size at one point in the past. An object of zero size is called a singularity and is the starting point of the Big Bang. The other possibility is that the Universe started at a non zero size and started expanding after that.There is no reason to believe this happened, and its hard to see a process by which it ever could.
Starting with a zero size Universe supports the Big Bang. It could also support a Universe created by God but the Bible doesn't mention a singularity anywhere.
If there was a Big Bang it must have created a huge amount of energy. In fact, it must have created so much that we would see the remnants of it even now, 14 billion years later. Its possible to ascertain theoretically what this energy would look like. In 1963 two scientists, Penzias and Wilson, were doing radio work at Bell Labs in a totally unrelated area found some noise (noise is a term which means a random unwanted signal, not necessarily sound), in their antenna they couldn't remove. It turned out the noise looked exactly like the noise expected from the Big Bang. Note that Penzias and Wilson didn't know anything about what was expected from this background noise and yet they found a very close match. Its possible to explain the background in other ways but the simplest explanation is the Big Bang.
The Universe is made from about 90% hydrogen, 10% helium and a tiny portion of other elements. This is the proportion predicted by the Big Bang theory. Its possible that if the Universe began in another way this same proportionality would have arisen but again the simplest explanation is the Big Bang. The proportion of other elements, such as isotopes of lithium, also supports the theory.
Observations of quasars at the observable limit of the Universe show that the Universe itself was different in the past. It has gradually changed after an initial phase where it was very different from today. This is consistent with the Big Bang but not with steady state theories and is not mentioned anywhere in the Bible.
There are several other areas of supporting evidence which are quite technical and beyond the level of what I want to cover here. They include observations of the types of sub-atomic particles, anisotropy of the background radiation, observations of galaxy clustering, abundance ratios of heavy elements and the domination of matter over anti-matter.
Scientists have tried to disprove this theory! There have been several tests applied to it since it was first formulated. These include: measuring the precise age of the Universe, measuring the point in time when galaxy formation began, observing the precise smoothness of background radiation, and validating supporting theories, especially relativity, and others. In every case the essential truth of the theory has been confirmed, although some details of the inflationary phase, etc have been modified. Unless something really big is discovered the Big Bang is safe as our accepted theory of the origin of the Universe.
Attempts at Discrediting the Big Bang
Some people who reject the Big Bang Theory suggest the red shift which demonstrates an expanding Universe originates through tired light or red shifting due to a background medium. This was a reasonable suggestion but has since been rejected after the red shift of gravitationally lensed objects was shown to be incompatible with it. Unfortunately Creationists don't seem to have caught up with this yet.
Another common problem is accepting the origin of the Universe from nothing. People who don't understand the fundamental laws of the Universe (especially quantum theory) find this hard to grasp. The fact is, at the quantum level, energy and matter can appear from nowhere if the total energy is low, and events can occur without a cause. Sounds weird, but as they say, if you don't think quantum theory is weird you obviously don't really understand it! Quantum theory has withstood intensive testing over the years and is a cornerstone of modern physics.
Finally, the opponents of the Big Bang like to quote cosmologists who themselves reject it. Unfortunately they tend to be very selective about who they quote and how. For example, Fred Hoyle, who was a leading exponent of the competing Steady State model many years ago is often quoted. These quotes are badly out of date and often show only selected parts of what the person has said. If a reference is provided its worth tracing it to see what year it was from and how much of the total quote is being presented.
Comment by Jonathon on 2007-08-16 at 11:49:57: I think that your big bang theory is ok although it has a few flaws. Quantum theory points toward there being a God. After all the Bible says the Universe was created from nothing. That is quantum theory as you earlier said. God didn't say that there wasn't a big bang and he doesn't go into detail on how he created the Earth. For all we know he could have created it that way. The Big Bang and religion can match each other perfectly after all if you look at it from everything you know you cannot create a house from blowing up pieces of wood.
Comment by OJB on 2007-08-16 at 14:44:08: You say the Big Bang has flaws (which I agree with) but what do you think those flaws are? Saying that the Big Bang and religion agree is a bit misleading because you are just making use of the vague nature of religious beliefs. The Bible gives a specific sequence of creation events which is definitely wrong. Re-interpret it all you like, but in the end the religious creation myth is useless, first because its so imprecise it could be interpreted many ways; and second, because where it does make specific statements we find they are wrong.
Comment by Anonymous on 2007-08-28 at 15:59:04: How can you believe a theory when it doesn't agree with what the laws of science say? The Big Bang says matter came from nothing. Physics says matter can't be created or destroyed. How do you explain that?
Comment by OJB on 2007-08-28 at 16:08:58: Yes, that is a tricky question all right. There are several possible explanations, but I have to admit that at this problem might not be answered until a new theory of "quantum gravity" can be devised. Current theories can only go back a certain time, then they fail. Note that this in no way supports a supernatural explanation. That's the classic "God of the gaps" fallacy. Anyway, here's a few ideas. First, according to quantum theory, matter can be created and destroyed, but only if the tota...
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