Lois & Clark Forums Forums General Discussion Off Topic The Big Bang and the Universe, final part: What was the Big Bang anyway?

Should you believe in the Big Bang? That's an interesting question, considering that I have named this entire series of "lectures" "The Big Bang and the Universe". So far, however, I haven't been talking too much about the Big bang itself. The astronomical magazines that I read are equally bored by the subject. If you want to be trendy and really in the know in the astronomical world, don't talk about the Big Bang!



Sorry to post pictures of shoes here, particularly since most of the words are in Swedish. But I think you know what I mean by this illustration. What's hot and what's not in the world of astronomy? Well, the Big Bang definitely is not!

The problem with the Big Bang is that it is such a dastardly irksome concept in the first place! First of all, if you assume that the Big Bang is a sort of fountain of creation from which all the matter and energy in the universe is bursting forth from a mathematical point, you are in trouble. If you pack all the mass and energy of the universe within a radius smaller than, say, our own Milky Way galaxy, all of this matter and energy is promptly going to collapse into a universe-mass black hole. Which is to say that if all this mass wasn't squeezed together into a single point before, it will be now! And a single point containing all the mass and energy in the universe is a concept that astronomers simply can't describe. Their best math and physics break down before such a completely outrageoues idea. Astronomers can't describe it, so they don't. Or, as Ludwig Wittgenstein put it: Whereof one cannot speak, thereof one must remain silent.



Ludwig Wittgenstein. Mum's the word.

It's not quite true that astronomers can't say anything about the subject. They can. The classic book about the Big Bang is Steven Weinberg's The First Three Minutes: A Modern View of the Origin of the Universe . Yes, but that book doesn't describe the Big Bang as such, not the exact moment of creation, but only the first three minutes following the Big Bang. And the book is from 1977, which should tell you something.



The book.



The cosmology it describes. Note that the book goes back to a time ten to the power of minus 43 seconds after the Big Bang, but not to the Big Bang itself.

So has cosmology been mired down in a mental swamp since 1977, so that it has been unable to make any new discoveries? Oh, no, no! The discoveries of recent times have been amazing! There is the theory of inflation, there is the detailed analysis of the echo of the Big Bang, the cosmic microwave radiation background (and you wouldn't believe what astronomers can infer from that!), and there are the discoveries of cosmic acceleration and dark matter and dark energy, among other things. Astronomy's view of the universe has undergone an extreme makeover since 1977, believe me!



The biggest "house" of them all, the universe, has undergone an "extreme makeover", at least in the minds of astronomers, since 1977!

But what astronomers love to talk about today is the universe they have recently revealed through their cutting-edge science and equipment, not the Big Bang itself. Astronomers will enthusiastically tell you about the age of the universe, which they firmly believe to be 13.75 billion years. After all, if you take the present rate of expansion of the universe and count backwards, plus take a number of other factors into account (such as the fact that no white dwarfs, burnt-out stellar cinders, have been found that are older than about twelve billion years, etcetera) astronomers are confident about their age-dating of the universe. Also, they are completely certain that when the universe was newborn, it was absolutely extremely dense, hot and tiny, and since then it has grown thinner, colder and larger all the time. And they are absolutely certain that the universe has evolved over time, that the first galaxies looked different the the ones we see today, that the first stars were different than the ones we see today, and so on. Oh yes, the universe has undergone an extreme makeover indeed!

So when astronomers tell you that they believe in the Big Bang - and they will tell you that, believe me - they really mean that they are believers in an expanding, evolving, changing universe that was born a little less than fourteen billion years ago.

But guess what? Recently, I've heard two Swedish professors of astrophysics talk about the Big Bang in a way that astonished me. They said that our universe started as a quantum fluctuation - I'm not going into that, sorry - but what happened was that there suddenly existed a humongous amount of potential energy in the universe. Think of it as if the ground beneath you suddnely disappears, the way if sometimes does in Donald Duck cartoons when Donald walks straight off a cliff and keeps walking, until he notices that the ground is gone beneath him.



What will happen when he realizes that he can't remain standing like this without toppling forward?

When Donald makes that discovery he will fall. And he will tumble down faster and faster, and he will pick up speed for as the slippery slope keeps sloping.

Now listen to what those professors of astrophysics said to me. They said that this is how the universe started out, when something started tumbling down a tremendous gravity well in something that existed before our universe was born. And this something kept falling and falling, and it fell faster and faster and faster...

Take a look at this graph. I know, I know, it's not an ideal graph for our purpose at all, but take a look at it any way:



Can you feel that something is "falling down" on the left side of this graph?

The thing falling down is inflation. Remember inflation ?

Astronomers describe inflation as an incredibly brief epoch a fraction of a nanosecond after the Big bang, when the universe underwent a "runaway blowup in size". Yes, but those two professors I listened to said that inflation happened first. It was inflation that kick-started the universe.

Inflation created the space, the emptiness, the "room" where everything else could take place.

Inflation was the epoch when something "fell down".

So what happened then, when this "something" hit "the ground"?

Why, you got a tremendous, tremendous, tremendous crash, of course. And this tremendous, tremendous, tremendous crash released a tremendous, tremendous, tremendous amount of energy. And guess what, this energy was later converted into matter, because according to Einstein's theory of relativity matter and energy are different aspects of the same thing.

So the creation of the universe can be regarded as a tremendous fall, inflation, followed by a tremendous crash, the Big Bang, which released all the energy and matter in the universe!



A much, much, much smaller crash than the one which created the universe.

Isn't it amazing? Humpty Dumpty sat on a wall, Humpty Dumpty had a great fall; All the King's horses and all the King's men, Couldn't put Humpty together again. And whatever came before our universe also had a great fall, and I don't think it could ever be put together again in the same shape as it was before.

But out of the crash and the ashes of this great fall was born our universe.

Ann