When the scriptwriters for Doctor Who imagined a futuristic device, they came up with the Sonic Screwdriver. Now a team of physicists at the University of Dundee have taken equipment designed for MRI-guided focused ultrasound surgery and demonstrated a real Sonic Screwdriver – lifting and spinning a free-floating 10 cm diameter rubber disk with an ultrasound beam.
Universtity of Dundee
[youtube:http://www.youtube.com/watch?v=SeB69CcLEI8]
Links
 |
In order to mark the centenary of Alan Turing’s birth, two of his mathematical research papers, believed to have been written whilst he was at Bletchley Park during World War II, have been released by GCHQ to The National Archives. |
Due to the sensative nature of the work done at GCHQ, the papers were not released earlier.
We are delighted to release these papers showing more of Alan Turing’s pioneering research during his time at Bletchley Park. It was this type of research that helped turn the tide of war and it is particularly pleasing that we are able to share these papers during this centenary year.
GCHQ spokesperson
The two papers are called “Paper on Statistics of Repetitions’ and ‘The Applications of Probability to Crypt’.
Paper on Statistics of Repetitions
In this paper Turing writes an informal report in which he works out the best statistical method of testing whether two cipher messages use the same key in parts of the message.
The Applications of Probability to Crypt
In this second paper, Turing applies rigorous probability analysis to coding problems of the day. One highlight is where Turing uses life expectancy to examine conditional probability. The associated example, “Hitler is now age 52”, adds piquancy and suggests that the paper was written between April 1941 and April 1942.
Links