a)The enigmatic life of J Robert Oppenheimer
Ray Monk spent 11 years working on his new biography of J Robert Oppenheimer, entitled Inside the Centre. In this podcast, he shares his understanding of the atomic-bomb pioneer's life, legacy and personality with reviews editor Margaret Harris.
Monk is a philosopher at the University of Southampton in the UK, and in the podcast you will hear him discuss the efforts he made to get to grips with Oppenheimer's physics – including his theoretical work on mesons and the gravitational collapse of neutron stars – as well as the atomic-bomb project. You will also hear Monk's views on the events that led to Oppenheimer having his security clearance revoked by the US government and the aspects of "Oppie's" character that made him such a charismatic leader.
b)A cloak in time
Not content with shielding objects in space, physicists have come up with a new way of concealing events in time. The research involves punching a series of temporal holes into a stream of optical data at gigahertz frequencies using commercially available equipment, and could lead to applications in telecommunications and computing that involve hiding or dividing up information.
Spatial invisibility cloaks are shields made up of artificial "metamaterials" that bend light waves around an object as if neither the object nor the cloak were present – just as a stream of water would flow around a boulder. A number of such devices have been built and successfully demonstrated, and now physicists are turning their attention to "temporal cloaks", which hide events during specific periods of time.
c)Physicists design acoustically invisible walls
A rigid wall can be transformed from a total reflector of sound to an almost perfect transmitter by perforating it with tiny, regularly spaced holes covered by a thin elastic membrane, say researchers in Japan and South Korea. The discovery, an acoustic analogue to extraordinary optical transmission (EOT), could potentially be used in microscopes, noise filters, new types of windows, acoustic concentrators and many other applications.
EOT was discovered by Thomas Ebbesen of the University of Strasbourg and colleagues in 1998. It allows electromagnetic waves to pass almost unhindered through a lattice of sub-wavelength holes in a barrier that would otherwise be opaque in some metamaterials. In Ebbesen's discovery, this was down to coupling between photons and electrons on the surface of the barrier.