Aristarchus: a bright lad

Some time in the third century BC, a fellow by the name of Aristarchus of Samos wrote a book in which he said the earth moved around the sun. The book's lost. We know about it because Archimedes quoted it with approval in a book of his own called The Sand Reckoner.
Aristarchus of Samos brought out a book in which the universe is many times greater than that now so called. His hypothesis is that the fixed stars and the sun remain unmoved, that the earth revolves about the sun in the circumference of a circle, the sun lying in the middle of the orbit, and that the sphere of the fixed stars, situated about the same center as the sun, is so great that the circle in which he supposes the earth to revolve bears such a proportion to the distance of the fixed stars as the center of the sphere bears to its surface.
That beats Copernicus by about 1,700 years.  It's when you read things like this that you realize how much was lost when the classical world collapsed.

Archimedes clearly bought into the theory. He wrote The Sand Reckoner to work out how many grains of sand it would take to fill up the universe, assuming Aristarchus was right. The numbers were so huge that to do it, Archimedes had to invent a whole new number system. The number of he got, in modern notation, was 8 x 1063 grains of sand, which is amazingly close to modern estimates for the number of known particles (though obviously we now know about massive amounts of vacuum too).

Archimedes finishes:
I conceive that these things will appear incredible to the great majority of people who have not studied mathematics, but that to those who are conversant therewith and have given thought to the question of the distances and sizes of the earth, the sun and moon and the whole universe, the proof will carry conviction. And it was for this reason that I thought the subject would not be inappropriate for your consideration.


Stephanie Thornton said...

I had not heard about Aristarchus, at least not that I can recall. Those pesky Dark Ages certainly ate up a lot of rather important information, didn't they?

L. T. Host said...

How I would have loved to go spend a few years in the library at Alexandria. Can you imagine the things that must have been in there?

This is amazing, thanks for sharing! It's really remarkable how much they knew/ figured out. Never ceases to amaze me.

Vicky Alvear Shecter said...

Fascinating! It is humbling to see their genius and know that most of it has disappeared.

Julie said...

Humbling's a good way to put it, Vicky. It's amazing. I can never wrap my head around it.

It's like the classical world was some kind of parallel universe, given how much they worked out and how much of it had to be discovered all over again.

Gary Corby said...

It's not impossible that other ancient books might still come to light. It was only a few years ago that the Archimedes Palimpsest was read for the first time, and that uncovered two new books that were thought gone forever!

The best hopes I suspect are to read off the pages used to make sarcophagi in Egypt in Hellenistic times, and check reused parchments from Byzantine and Mediaeval libraries. That's where the discoveries seem to come from.