When University of Maryland physicist Timothy Koeth received a mysterious heavy metal cube from a friend as a birthday gift several years ago, he instantly recognized it as one of the uranium cubes used by German scientists during World War II in their unsuccessful attempt to build a working nuclear reactor. As Heisenberg himself reported, the German scientists’ final experiment failed because the amount of uranium in the cubes was insufficient to trigger a sustained nuclear reaction. During their quest, Koeth and Hiebert uncovered a box of declassified documents about German uranium in the National Archives and discovered there were about 400 other uranium cubes from a separate reactor experiment by the Gottow group.

Postdoctoral Researcher Physics, Duke University and particle physicist at CERN
I think the hottest known objects in the universe are the collision points created by heavy ion collisions like those at RHIC, at Brookhaven on Long Island, and here at the Large Hadron Collider at CERN. When we collide heavy ions at about 5 tera electron Volts in the Large Hadron Collider, the LHC is both the coldest extended object in the universe—because the 27-km of magnets used to bend and steer the beam in the LHC tunnel are bathed in liquid helium at 1.9 K, colder than the 2.7 K of outer space—and is simultaneously creating the places, the collision points, with the hottest temperatures in the universe. As with the QGP, deciding when it first becomes a thermalized object depends on the definition of ‘object,’ but even ignoring the very early (and very hot) times that we can really only speculate about, it is easy to get temperatures above 100 trillion trillion degrees.

Instead, when he analyzed the sample, he was amazed to see that primers could pull out the DNA of ancient mammoths, bison, horses and a variety of plants. Sometimes the scientists use universal primers, which recognize small sequences of DNA from all the organisms in one species or family; these molecules can then identify all the plant DNA or animal DNA to be amplified, or replicated, through the polymerase chain reaction. Jamie Wood, a paleoecologist at Manaaki Whenua Landcare Research who studies ecosystem function and composition in New Zealand over the past 50,000 years, explains that painstaking measures also have to be taken to ensure modern DNA doesn’t get mixed up in the ancient sample.