I haven’t written in detail about the history of the universe before, but with an important announcement coming up today, it was clearly time I do so.
Let’s start from the beginning. How did the universe begin?
You may have heard that “the Big Bang theory says that the universe began with a giant explosion.” THIS IS FALSE. That’s not what the original Big Bang Theory said, and it’s certainly not what the modern form of the Big Bang Theory says. The Big Bang is not like a Big Bomb. It’s not an explosion. It’s not like a seed exploding or expanding into empty space. It’s an expansion of space itself — space that was already large. And in the modern theory of the Big Bang, the hot, dense, cooling universe that people think of as the Big Bang wasn’t even the beginning.
How did the universe begin? We haven’t the faintest idea.
That’s right; we don’t know. And that’s not surprising; we can trace the history back a long way, an amazingly long way, but at some point, what we know, or even what we can make educated guesses about, drops to zero.
Unfortunately, in books, on websites, and on many TV programs, there are many, many, many, many, many descriptions of the universe that say that the Big Bang was the beginning of the universe — that the universe started with a singularity (one which they incorrectly draw as a point in space, rather than a moment in time) — and that we know everything (or can guess everything) that happened after the beginning of the universe. Many of them even explicitly say that the Big Bang was an explosion, or they illustrate it that way — as in, for instance, Stephen Hawking’s TV special on the universe. [Sigh --- How are scientists supposed to explain these ideas correctly to the public when Stephen Hawking's own TV program shows a completely misleading video?!] This is just not true, as any serious expert will tell you.
So what do we actually know? or at least suspect?
Out of the fog of our ignorance comes the strong suspicion — not yet the certainty — that at some point in the distant past (about 13.7 billion years ago) the part of the universe that we can currently observe (let’s call it “the observable patch” of the universe) was subjected to an extraordinary event, called “inflation”.
We suspect it. We have some considerable evidence. We’re looking for more evidence. We might learn more about this any day now. Maybe today’s our day.
Stay tuned for the announcement of a “Major Discovery” out of the Harvard-Smithsonian Center for Astrophysics later today. And then stay further tuned for the community’s interpretation of its reliability.