Hans Bethe, one of the Twentieth century's greatest theoretical physicists passed away peacefully last night, at the age of ninety-eight. For Cornell, this is a very sad day. Bethe was very a very important part of the Cornell community. He basically put Cornell on the map as far as physics goes. Today, thanks to his work, Cornell is a world leading physics school, with strong programs in virtually all areas of physics.
The strength and diversity of the department here is a direct reflection of Hans Bethe's strength and diversity as a theorist. John Bacall's quote is appropriate: "If you know his work, you're inclined to think that he is many different people, all of whom have gotten together and formed a conspiracy to sign their papers under the same name."
In an era of increasing specialization, Bethe worked in many fields. For example, he won the Nobel Prize for his work in stellar astrophysics. Basically, he worked out why stars shine. Many quantum field theorists will know about another important piece of work, his back of the envelope calculation of the Lamb shift. This was the first calculation which showed that renormalization might work, and spurred the development of renormalization theory by Schwinger and Feynman. He did pioneeing work in condensed matter physics, quantum mechanics, and astrophysics, staying active well into his nineties.
It would be totally impossible to summarize his career here, Bethe's contributions to modern physics have been too wide. Indeed his biographer, Sam Schweber has been working for years on a multi-volume biography. For those who are interested in learning a bit more about Hans Bethe, Cornell has a webpage with some biographical information, and videos. The video "I can do that", linked from the "reading" page, offers a nice overview.