Why A Medium-Sized Black Hole Is Surprising Physicists If you’re looking for a black hole, they normally come in two sizes. There’s the basic model, in which a large, dying star collapses in on itself, and the gravity of its core pulls in other matter. Then there are the supermassive black holes, millions of times the mass of our sun, that tend to be found at the center of a galaxy. But recently researchers reported that they had evidence for two colliding black holes that created a surprising offspring. Their collision formed a middle-weight black hole, around 142 times the mass of our sun.  Daniel Holz, a member of the LIGO team that spotted the collision, and a professor of astronomy and astrophysics at the University of Chicago, joins Ira to talk about what the observation means for theories of how black holes form and grow. Against Impossible Odds, The Warsaw Ghetto Stopped A Typhus Outbreak This year marks the 80th anniversary of the establishment of the Warsaw Ghetto in November of 1940. The Nazis purposefully tried to starve to death almost half a million Jews, who were kept with little food and water in a space about the size of Central Park.  Theoretical mathematician Lewi Stone of Tel Aviv University has been studying a concurrent public health crisis that happened in the Warsaw Ghetto: a Typhus outbreak. The infectious disease is spread by lice, and can be deadly.  Typhus ran rampant in the Warsaw Ghetto for the better part of 1941. But when the winter rolled around, the expected second wave never came. Researchers have found evidence that public health measures enacted under these impossible circumstances—think public education and social distancing—actually worked. Stone talks to SciFri producer Kathleen Davis about this research, and potential takeaways for 2020’s public health crisis.  It’s Still A Wild, Wonderful World The table of contents for poet Aimee Nezhukumatathil’s new book of essays reads like a list of evolution’s most fantastic products. The comb jelly, which pulses with rainbow bioluminescence. The smiling-faced axolotl, which can regrow lost limbs and is a star of biology research labs, but is considered critically endangered in the wild. The human-sized corpse flower, which blooms for a mere 24 hours, smelling of dead flesh. It’s also a deeply personal book: Nezhukumatathil says the screaming pink of dragonfruit signals “summertime, pop music, sunglasses balanced on the top of my head, weather too warm for socks.” A firefly’s spark might send her back to her grandmother’s backyard, or “to splashing in an ice-cold creek bed, with our jeans rolled up to our knees, until we shudder and gasp, our toes fully wrinkled.” Even the horizontal eye of an octopus becomes a “door that judges us,” as the oceans become increasingly difficult to inhabit, thanks to humans’ ravages. Science Friday’s Christie Taylor talks to Nezhukumatathil about her experiences in natural wonder, and why in a world of changing climate, rising seas, and burning forests, she finds it important to share her joy in learning about the creatures we share the planet with.