Category Archives: Science

Wood Wide Web

Peter Wohlleben auf SWR4: Das geheime Leben der Bäume. (YouTube, knapp 18 Minuten)

“Bäume sprechen miteinander, sie haben ein kollektives Gedächtnis. Klingt unglaublich, ist aber wissenschaftlich belegt. SWR4 Redakteur Lars Michael Storm und Filmemacher Beat von Stein haben Förster Peter Wohlleben in seinem Wald getroffen.”

Das gleichnamige Buch habe ich vor einer Weile gelesen und fand es sehr informativ und interessant. Leseempfehlung!

Siehe auch Peter Wohlleben im Dialog mit Michael Krons am 08.11.2015 (YouTube, 35 Minuten).

Das Dreikörperproblem

… musste ich in meinem dritten Semester an der Uni für den Schein in theoretischer Physik Mechanik programmieren. Das sah natürlich längst nicht so schick aus wie diese Website, und davon abgesehen hatte ich einen Fehler im Programm, den ich erst nach mehreren Tagen gefunden habe – es war ein Vorzeichenfehler.

PhET Interactive Simulations, University of Colorado: My Solar System. (Flash)

You can simulate the orbits of two, three or four objects and change the mass, initial position and velocity for each one individually. Try to find stable or chaotic orbits!

“Hahn: If they have really got it, they have been very clever in keeping it secret.”

German History in Documents and Images: Transcript of Surreptitiously Taped Conversations among German Nuclear Physicists at Farm Hall (August 6-7, 1945).(PDF)

“At the beginning of the war, Germany’s leading nuclear physicists were called to the army weapons department. There, as part of the “uranium project“ under the direction of Werner Heisenberg, they were charged with determining the extent to which nuclear fission could aid in the war effort. (Nuclear fission had been discovered by Otto Hahn and Lise Meitner in 1938.) Unlike their American colleagues in the Manhattan Project, German physicists did not succeed in building their own nuclear weapon. In June 1942, the researchers informed Albert Speer that they were in no position to build an atomic bomb with the resources at hand in less than 3-5 years, at which point the project was scrapped.

After the end of the war, both the Western Allies and the Soviet Union tried to recruit the German scientists for their own purposes. From July 3, 1945, to January 3, 1946, the Allies incarcerated ten German nuclear physicists at the English country estate of Farm Hall, their goal being to obtain information about the German nuclear research project by way of surreptitiously taped conversations. The following transcript includes the scientists’ reactions to reports that America had dropped an atomic bomb on Hiroshima. The scientists also discuss their relationship to the Nazi regime and offer some prognoses for Germany’s future. As the transcript shows, Otto Hahn was especially shaken by the dropping of the bomb; later, hecampaigned against the misuse of nuclear energy for military purposes.”

Link via MetaFilter.

When a line isn’t a dotted line

The day before yesterday I linked to an XKCD comic called A Timeline of Earth’s Average Temperature.

NPR: Epic Climate Cartoon Goes Viral, But It Has One Key Problem.

“The solid line comes from real data — from scientists actually measuring the average temperature of Earth’s surface. These measurements allow us to see temperature fluctuations that occur over a very short timescale — say, a few decades or so.

But the dotted line comes from computer models — from scientists reconstructing Earth’s surface temperature. This gives us very, very coarse information. It averages Earth’s temperature over hundreds of years. So we can see temperature fluctuations that occur only over longer periods of time, like a thousand years or so. Any upticks, spikes or dips that occur in shorter time frames get smoothed out.”