The first thing by Hubert Reeves that I came across was L'univers expliqué à mes petits-enfants
, and now I can't read anything he's written without imagining his charming granddaughter's interruptions. So, with apologies:Grandpa, what is your book called?
The title is La première seconde
. And what's it about?
What it sounds like! The first second of the Universe.You can write a whole book about that??
You certainly can! You remember I said that the nearer you come to the beginning of the Universe, the hotter it gets? And I'm sure you've learned in your chemistry class that heat makes things happen faster...Yes...
Well, during the first second of the Universe, things were MUCH hotter than they've ever been since. Hotter than the inside of the Sun. Hotter than a hydrogen bomb exploding. And that made things happen very fast indeed.What kind of things?
Amazing things! All the subatomic particles that make up atoms - electrons, protons, neutrons - got created. Photons, the particles that light is made of, got created. And space itself expanded from a size much smaller than an atom to a size maybe a few centimeters across...All that in one second?
In fact, most of it happened in much less than a second!But how can we know?
We aren't sure about all of it. The good thing is that we can still see the light from the beginning of the Universe. It's coming from every part of the sky, and by studying that carefully we can figure out a lot about what happened. That light comes all the way from when the Universe was a second old?
A good question! I'm afraid it doesn't. It actually comes from what we call the Last Scattering Surface, when space became transparent. That was when the Universe was about three hundred thousand years old. But we can still understand a lot from the patterns in it. And there are other clues too...Like?
Well, have you ever thought how strange it is that there are any solid things at all? Nearly all the particles in the Universe turn out to be photons - only one in a billion is something else. We could have nothing but light, but we don't. That tells us something very interesting.What a strange thought! Wait, here's another thing I want to know. You said that during the first second, the Universe was hotter than anything there's ever been since. But if scientists have never seen anything that hot, how do they know what happens then? Maybe there are new scientific laws they can't even imagine. Does that make sense, Grandpa?
Another good question! You're right, we don't know what happens when things are very, very hot. But we can guess. Maybe our guesses are wrong, but we put together the things we do know and see if they fit. All the same, I must admit that we're just guessing in the end.Now I want to read your book to find out more, Grandpa! But will I understand it?
I've tried to write it so you will! I know you like skiing. Well, the book is like a skiing resort. Most of the chapters are marked as green trails, and if you stick to those it won't be too hard. But if you want something more challenging, you can try reading the red chapters too. Hm... let me look. This is harder math than we've done in school! Could you understand this when you were my age, Grandpa?
A bit, I think...Then I'll see if I'm as smart as you were! Lend it to me and I'll give it back next week and tell you what I thought.
That's my girl!
________________________________________Hello again Grandpa!
Hello sweetheart! So did you like the book?Well Grandpa, I couldn't stop thinking about that thing you said. How everything might just have been light! I read that part of the book three times, and I talked to another girl who knows more science than I do, and I looked up some stuff on the Internet.
And was that interesting?Oh yes, Grandpa, amazingly interesting! You never said how CP violation requires having three generations of particles, because otherwise you couldn't have complex phases in the CKM matrix. That's so clever!
Ah...And I found that there isn't enough known CP violation to explain the matter to radiation balance. So there must be other kinds of CP violation we haven't found yet. Or maybe there's a fourth generation of particles. What do you think, Grandpa?
Well...You'll put all this stuff in the next edition, won't you? I promise I'll read it the moment it's out!
Sweetheart, I promise I will. I'm thinking about it in my head right now.Thank you Grandpa!