Ask a Spaceman!

Ask a Spaceman! runs on questions, and its episode titles make that obvious. They include 'AaS! 265: Does Antimatter Fall Up?', 'AaS! 267: Is the Universe Older than We Think?' and 'AaS! 269: Why Are Interstellar Objects So Weird?'. The answers come from astrophysicist Paul M. Sutter, and the questions keep coming because listeners are asked at the close to send more by email or through the show's website. His habit is to start small. A car with a license plate from the far side of the world tears through a sleepy town, and that becomes the way into interstellar visitors. A key that opens a stranger's car sets up the question of why mathematics fits the universe so well, and then Tegmark's stronger claim that the universe is nothing but math. Apollo 15 astronaut David Scott dropping a hammer and a feather on the Moon leads, eventually, to Dirac fretting over negative energy solutions and how deep they could go. The analogies are only a way in. On the age of the universe, the 13.77 billion year figure is stated with mock pride in its decimal places and then taken apart: how is it measured, and what does it even mean for a whole universe to have an age? The answer runs through the FLRW metric, the simplifying model that supplies a universal clock, along with the old line that all models are wrong but some are useful. Sutter will ask what happens if a model fails. He will also say when a puzzle is not strong enough to break one. Little red dots strain normal star formation, yet he doubts they will overturn cosmology, and he floats intense star formation as another reading. On interstellar comets he separates the dull from the strange, with Borisov on one side and Atlas on the other, and suggests they may be a different breed because they formed around another star with different chemistry. The quantum eraser episode comes with an admission that some experiments make him angry, at himself rather than at nature. From there it moves to double slits and wave-particle duality, noting that the effect has been reproduced with electrons, atoms, Buckminster fullerenes and molecules of up to 2,000 atoms. The humor is dry and frequent. Experimentalists, he remarks, did not get enough sleep as a group. Episodes close by thanking Patreon supporters by name, with the same sign-off promising more complete knowledge of time and space. A good first listen is 'AaS! 267: Is the Universe Older than We Think?', which shows the whole method: a confident number, a pointed question, and a model examined on its own terms.