Thursday, February 19, 2009

The Big Bang

While scientists don’t have an immediate answer to how the first life arrived on Earth, they have an excellent idea about how the universe itself came into existence. The Big Bang is the name of the singular event that most scientists believe initiated the beginning of our universe.

Probably for the entire time that humans have had the intellectual ability to think of such things, there were differing opinions over whether or not the universe had existed forever or whether it began at a single point in time.

Aristotle felt that the universe had existed forever. Christian theologians, based on a reading of the Bible of course, felt that the universe began at a particular time. (They even suggested a date and time for that creation of the universe.)

The debate went back and forth for much of human history. In the 20th century Albert Einstein noticed that his description of General Relativity did not allow for the solution of a static universe. Einstein’s philosophical view was that the universe had existed forever – an idea called a “steady-state” universe. Famously, he added a “cosmological constant” that allowed for such a thing.

Early in the 20th century, scientists started to see evidence that the universe was expanding. It is worth noting that some of the 20th century proponents of this expansion of the universe were theists. For example, beginning in 1925 Abbé Georges Lemaître, who was both an astrophysicist and a Jesuit priest, was the first scientist to promote a big bang creation event.

In 1929, the most significant piece of evidence supporting this expansion was presented by the astronomer Edwin Hubble. Hubble discovered that, relative to the Earth, the galaxies are receding in every direction at speeds directly proportional to their distance from the Earth. In other words, the universe was expanding in all directions much like a balloon expands as it is blown up.

If the entire universe is expanding now, then it makes sense that if you play the universe’s history backwards, what do you see? Imagine what happens when you deflate a balloon. Eventually the universe would have existed as a single point in space. If that was the case, then the universe had a beginning.

That hypothesis raised many questions.

Is there any evidence, other than an apparently expanding universe, that any of this really happened?

When was the universe created?

Why is it called the “Big Bang”?

What caused the Big Bang in the first place?

Does the Big Bang prove the Bible to be wrong?

I will try to answer those questions in additional BLOG entries.

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