Universal interferometric signatures of a black hole's photon ring.

The Event Horizon Telescope image of the supermassive black hole in the galaxy M87 is dominated by a bright, unresolved ring. General relativity predicts that embedded within this image lies a thin "photon ring," which is composed of an infinite sequence of self-similar subrings that are indexed by the number of photon orbits around the black hole. The subrings approach the edge of the black hole "shadow," becoming exponentially narrower but weaker with increasing orbit number, with seemingly negligible contributions from high-order subrings. Here, we show that these subrings produce strong and universal signatures on long interferometric baselines. These signatures offer the possibility of precise measurements of black hole mass and spin, as well as tests of general relativity, using only a sparse interferometric array.

Blacked-out spaces: Freud, censorship and the re-territorialization of mind.

Freud's analogies were legion: hydraulic pipes, military recruitment, magic writing pads. These and some three hundred others took features of the mind and bound them to far-off scenes--the id only very partially resembles an uncontrollable horse, as Freud took pains to note. But there was one relation between psychic and public act that Freud did not delimit in this way: censorship, the process that checked memories and dreams on their way to the conscious. (Freud dubbed the relation between internal and external censorship a 'parallel' rather than a limited analogy.) At first, Freud likened this suppression to the blacking out of texts at the Russian frontier. During the First World War, he suffered, and spoke of suffering under, Viennese postal and newspaper censorship--Freud was forced to leave his envelopes unsealed, and to recode or delete content. Over and over, he registered the power of both internal and public censorship in shared form: distortion, anticipatory deletion, softenings, even revision to hide suppression. Political censorship left its mark as the conflict reshaped his view of the psyche into a society on a war footing, with homunculus-like border guards sifting messages as they made their way--or did not--across a topography of mind.

Focus: the elusive icon: Einstein, 1905-2005. Introduction.

As Einstein's portrait comes increasingly to resemble an icon, we lose more than detail--his writings and actions lose all reference. This is as true for his physics as it is for his philosophy and his politics; the best of recent work aims to remove Einstein's interventions from the abstract sphere of Delphic pronouncements and to insert them in the stream of real events, real arguments. Politically, this means attending to McCarthyism, Paul Robeson, the Arab-Israeli conflict. Philosophically, it means tying his concerns, for example, to late nineteenth-century neo-Kantian debates and to his own struggles inside science. And where physics is concerned, it means attending both in the narrow to his responses to others' work and his reactions to his own sometimes misfired early work on, for example, general relativity and to the wider context of technological developments. Einstein remains and will remain a magnet for historians, philosophers, and scientists; the essays assembled here represent a strong sampling--but only a sampling--of a fascinating new generation of work on this perennial figure.