Sunday, November 29, 2015

Special Relativity and General Relativity Explained With A Ten Hundred Word Vocabulary

A quite lucid explanation of special relativity and general relativity with a limited vocabulary by Randall Munroe of xkcd fame has been reprinted at the New Yorker. A taste:
There once was a doctor with cool white hair. He was well known because he came up with some important ideas. He didn’t grow the cool hair until after he was done figuring that stuff out, but by the time everyone realized how good his ideas were, he had grown the hair, so that’s how everyone pictures him. He was so good at coming up with ideas that we use his name to mean “someone who’s good at thinking.”

Two of his biggest ideas were about how space and time work. This thing you’re reading right now explains those ideas using only the ten hundred words people use the most often. The doctor figured out the first idea while he was working in an office, and he figured out the second one ten years later, while he was working at a school. That second idea was a hundred years ago this year. (He also had a few other ideas that were just as important. People have spent a lot of time trying to figure out how he was so good at thinking.)

The first idea is called the special idea, because it covers only a few special parts of space and time. The other one—the big idea—covers all the stuff that is left out by the special idea. The big idea is a lot harder to understand than the special one. People who are good at numbers can use the special idea to answer questions pretty easily, but you have to know a lot about numbers to do anything with the big idea. To understand the big idea—the hard one—it helps to understand the special idea first.

Saturday, November 28, 2015

Ancient DNA from Neolithic Greece and Anatolia

Investigators have managed to get right to the source of the European Neolithic Revolution with ancient DNA from Greece and Anatolia, which is described in two new papers.

Like all other Early European Farmers, genetically, they are quite similar to modern day Sardinians and lack the European and Central Asian steppe contribution that is ubiquitous in most modern European populations.

The Y-DNA in the Neolithic Greeks and Anatolians was, unsurprisingly G2a2.  The mtDNA of two Mesolithic individuals was K1c and the mtDNA of two Neolithic individuals was K1a2.

Of course, their genes look quite unlike modern Greeks and Turks.