Daniel and Kelly dive into the history of medicine, and discuss the data John Snow collected to argue that cholera is transmitted through contaminated water and not foul-smelling air. These data bolstered the emerging germ theory of disease.

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Daniel and Kelly answer questions about tongue worms, units, and Kelly's nightmares.

Link: Standard reference peanut butter

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Daniel and Kelly explore the structure of the space between solar systems and reveal our cosmic context.

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Daniel and Kelly talk about the challenges of hot fusion and the frustrated potential of cold fusion. And Keanu Reeves.

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Daniel and Kelly answer questions about the expanding universe, how sleep aids impact sleep quality, and what characteristics might make aliens better adapted for interstellar travel.

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Daniel and Kelly welcome Dr. Scott Solomon back on the show to talk about his new book Becoming Martian: How Living in Space Will Change our Bodies and Minds.

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Daniel and Kelly discuss Elon Musk's recent announcement that SpaceX has shifted focus from a self-sustaining settlement on Mars to a self-growing city on the Moon.

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Daniel and Kelly answer questions about how it can both be true that humans share 98.7% of their DNA with bonobos and that fraternal twins share 50% of their DNA, why black holes don't have color charges, and whether or not you could treat a fever or let it ride.

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