MIT physicist David Kaiser is one of those rare scientists who can make mind-bending physics feel like a great conversation over coffee — funny, generous, and genuinely thrilled by what we still don't know. And what he's working on is wild. What the if the universe is packed with invisible black holes smaller than an atom? Dave thinks the mysterious "missing stuff" that holds galaxies together might not be some exotic undiscovered particle — it could be tiny black holes that formed a split second after the Big Bang. If he's right, a handful of them could be cruising through our solar system right now, and we might be able to catch one in the act just by watching Mars wobble. We also dig into whether a rogue black hole might have flattened a Siberian forest in 1908, and rest assured, the residents of Brooklyn have nothing to worry about.

Learn more about David Kaiser's primordial black hole research:

MIT PBH Research Group: https://sites.mit.edu/mitpbh/

David Kaiser's essay in the London Review of Books — a great accessible overview with historical context: https://www.lrb.co.uk/the-paper/v46/n11/david-kaiser/black-hole-flyby

The ultrahigh-energy neutrino paper (open access): https://journals.aps.org/prl/abstract/10.1103/vnm4-7wdc

"Close Encounters of a Primordial Kind" — the Mars wobbles paper: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.110.063533 (also available open access on arXiv: https://arxiv.org/abs/2312.17217)

Primordial black holes with QCD color charge (open access): https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.231402

Full list of press coverage: https://sites.mit.edu/mitpbh/news/

Selected press coverage:

MIT News — Exotic black holes could be a byproduct of dark matter: https://news.mit.edu/2024/exotic-black-holes-could-be-dark-matter-byproduct-0606

MIT News — Mars wobble could be dark matter: https://news.mit.edu/2024/mars-wobble-could-be-dark-matter-mit-study-finds-0917

MIT News — Could a primordial black hole explain a mysteriously energetic neutrino?: https://news.mit.edu/2025/could-primordial-black-holes-last-burst-explain-mysteriously-energetic-neutrino-0918

CNN — Black holes and dark matter: https://www.cnn.com/2024/06/17/science/black-holes-dark-matter-scn/index.html

LA Times — Tiny black holes zipping through the solar system: https://www.latimes.com/science/story/2024-09-17/tiny-black-holes-zipping-through-the-solar-system

Scientific American — Dark matter black holes could fly through the solar system once a decade: https://www.scientificamerican.com/article/dark-matter-black-holes-could-fly-through-the-solar-system-once-a-decade/

Quanta Magazine — Monster neutrino could be a messenger of ancient black holes: https://www.quantamagazine.org/monster-neutrino-could-be-a-messenger-of-ancient-black-holes-20260123/

APS Physics — "The Solar System as a Black Hole Detector" (Mars wobbles): https://physics.aps.org/articles/v17/s98

APS Physics — "New Suspect for Neutrino Signals" (neutrino paper): https://physics.aps.org/articles/v18/s124

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