How old is the universe? I like to ask this question to non-scientists to tease out in which kind of the world they think they are living.
The most interesting answer was from a Baptist priest sitting next to me on a trans-Atlantic flight to San Diego: 4000 years! I was a bit shocked as I have never met one of them. I politely asked him to explain the fossil finds in deep geological layers that are millions of years old. He quickly and confidently replied: Ah, that's the greatness of God. He made it all look as if it were millions of years old! To which I had no reply, because the man was logically consistent. If you assume an all mighty God, he could just about do that! Of course, such a theory does not explain why
those giant dinosaur bones are only to be found in higher layers and the deepest layers only contain fossilized uni-cellular organisms. A wimp of God? Or is there a reason? But if you don't really care about such details, as probably nearly everyone I ever met, no difference!
The backbone of our society, the middle class profession of lawyers, teachers, architects, journalists and medical doctors are completely taken by surprise. You would have thought that the people who we trust our law suits, children, houses, news and bodies should know better. They know a lot about their immediate culture: French grammatical rules that do not change the meaning of the sentence, the latest tax tricks, literature and arts. But such a basic fundamental question of human existence. They never ever thought about the age of the place they live in, and do not seem to have any mental framework to think about these questions. Never had it in school. Many say a few millions years. I always try to tease out why only a few millions. First, a few millions is a big number and the universe must be very old. Second, they have a skewed view of the world. The oldest cave paintings are 5000 years old, the first humans 50'000 years old, the dinosaurs 100'000s of years, and the earth 1 million year old.
The scientifically most satisfying answer typically comes from my nerdy engineering or computer science friends or those who did not have a university education but show a genuine interest and curiosity in the world around us: a few billions years. They also didn't have it school, but they were interested to find out more. They didn't get the numbers right, but they got the timescale right. Mostly because the dinosaurs are 100 million years old or so, and so earth must be considerably older: maybe 1 or 2 billion years. And so the universe is still a bit older. The most unsatisfying answer for me is the right answer with no understanding. Reminds me of those school friends who learned all by heart but never fully understood. Why this age? They say that they heard it or read it somewhere. In fact, they have no clue what is going on. They just repeat the number like a parrot.
The last category of people weasel out. They claim it is not possible to do, and the answer cannot be right because that would mean that time itself started which they find is impossible. If I am ever accused of murder, they will prove be of extreme help to my defense team. Yes, it is possible to estimate the age of our universe as we know it. Maybe there was something before the big bang, maybe not. We can still say when the big bang happened, because we still see the effect of it now. If you look carefully at the stars, they are all drifting away from each other. Blow up a balloon a bit, draw two black dots, and blow up further. The dots move away and that's what astronomers see. And scientists are using this expansion to estimate when all dots were together: like a reverse movie. Another way to estimate the age is to find the oldest object in the universe and you have a lower limit for the age of the universe. Measurements have shown that some stars are older than 10 billion years.
So how old is the universe? Of course, I will not tell. You will know a number. Look it up yourself, and try to understand why that number. If you do that, you do science. If not, you are a parrot of our culture or a victim of your own imagination.
Tuesday, January 12, 2010
Parrots of our culture
I wrote this piece for a newspaper: