Writing Worth Reading
Writing Worth Reading
Book two. Quantum Mechanics by Albert Messiah.
This is a graduate level physics book, not an undergraduate book. I read it when I started my PhD in theoretical physics. It was originally written in French and it’s where I really learned about quantum mechanics. It goes further than all that undergraduate crap about atoms being in two places at once and it throws a lot of the laws of physics out of the window and says…
Wait. An atom can be in two places at once?
Yes. You cannot say for sure where an atom is until you look at it. Looking at it makes it decide. Only when you look at it is it in one place.How do you know? Do you pretend you’re not looking?
Well, yes. I mean, you don’t look. You send an atom through something with narrow slits in the top and bottom and you hear see a blip when it hits the other side. You send loads of atoms and so would expect to see loads of hits at the top and the bottom adjacent to the two slits. But you don’t. What you get is an interference pattern like you would with waves washing through both slits at the same time. But you get his effect even when you send only one atom at a time. But if you spy on it then it only goes through either the top or the bottom and not both at once. It’s as though it knows you’re looking.
Why?
If I knew that then the King of Sweden would be calling me up with the Nobel. It’s counterintuitive and weird but we’ve learned to accept it. Quantum mechanics is hugely accurate – most of modern scientific development is based on it and on what it tells us about the subatomic world, but at its heart it says that an atom can be in two places at once. We’ve learned to live with that.
If atoms are so unreliable why isn’t everything fluid?
You mean why doesn’t your hand go through a table? Because electromagnetic forces hold the atoms together and give rigidity. Atoms themselves are mostly empty space – there’s a nucleus and then these electrons buzzing around. The nucleus has a positive charge and the electrons have a negative charge, so the negative charges repel each other and it is this electromagnetic force between the atoms in my hand and the atoms of the table that give rigidity and solidity.
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Jim Al-Khalili is a scientist, author and broadcaster. He is Professor of Theoretical Physics and Public Engagement in Science at the University of Surrey.
