Anotherblog

Bathroom renovations

…have started. The ensuite bathroom is stripped bare, and there are sheets all over everything in the main bedroom, and the living room is filled with bathroom things. We’re sleeping in the guest bedroom, which, as it turns out, doesn’t have particularly effective curtains.

It’ll be nice when this is over (in about two week’s time). That’s the last of the big spending for a while.

Meanwhile, Mr Doug Schepers dropped in to Sydney. We talked SVG and science fiction and philosophy, as usual, and hats were thrown in the air to many shouts of “Spiffing!” and “Tally-ho!”.

It turns out that four days of playing Dominion, Carcasonne, Dominion:Intrigue, Bananagrams, Ingenious, Cash ‘n Guns, Magic The Gathering, and Poison does interesting things to my dreams.

The Earth, and the Universe

I went to a really good lunchtime seminar by DMM last week, and had my mind blown open by something that should have been obvious (and is to any astrophysicist).
So, after the big bang, the only atoms in the universe were hydrogen, helium, and a touch of lithium. These congealed into stars, which fused elements into heavier elements, ending with iron. Every metal heavier than iron comes from a supernova explosion.
I had never really thought this through or had it explicitly explained to me, but of course this means that first generation stars, formed directly from the big bang, don’t have planets. Planets can only form from supernova debris. Our sun is obviously not a first generation sun. But what generation is it?
Second. It’s a second generation sun. It and us are formed from the debris of first generation suns going supernova.
I’d always had the vague feeling that the universe had been going on a very long time. And yes, it has, but in terms of the *potential* lifetime of the universe, it’s in its infancy. Only a tiny fraction of the hydrogen and helium from the big bang have been converted into heavier elements. Most of the stars we can see are first generation (and are thus skipped in searches for extraterrestrial life, on the principle that life is less likely to be made using hydrogen and helium alone, or inside a sun.) This should have been obvious to me, really – the universe is about 12 billion years old, and the Earth is about 5 billion years old. Of course we’re second-generation.
On an astronomical timescale, life has been observed to happen pretty as soon as it could have. The question is not whether intelligent extraterrestrial life has formed – it almost certainly has – but how far away it is.