NASA's image of astronaut Bruce McCandless II on a spacewalk a few meters away from the cabin of the space shuttle Challenger on Feb. 7, 1984.
NASA's image of astronaut Bruce McCandless II on a spacewalk a few meters away from the cabin of the space shuttle Challenger on Feb. 7, 1984.

Things You Thought You Knew

Image Credit: NASA.
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About This Episode

There are some things you thought you knew and on this episode of StarTalk Radio, Neil deGrasse Tyson and comic co-host Chuck Nice are here to investigate what we know and what we thought we knew.

We start with mass, weight, and density. If you’re trying to get in shape you need to lose weight, right? Neil deGrasse Tyson says wrong. Neil tells us why when you want to get in shape, you need to lose mass. You’ll learn why a weight-loss book written by a physicist would just be one sentence. We explore the difference between mass and weight and why weight is all about forces. Find out why heavy cream is lighter than skim milk. We explore how the hull of a ship keeps the ship buoyant. All that, plus, Neil explains why, if you want to lose weight quickly, just head to the Moon and hop on a scale.

Then, we move on to another seemingly simple question: Why does ice float? Neil explains why peculiar things happen to water when it changes state. We explore what happens when water freezes. Chuck gives a demonstration of why you usually see 10% of ice above water. You’ll learn why the arctic ice sheets float on the water. And, why the ice we need to worry about is the ice on land and the “runoff.” We discuss the power of freezing ice (which leads to bursting pipes). Find out more about the density of water. What if bodies of water froze from the bottom up? Neil tells us how a certain property of water protects aquatic life over the winter.

Lastly, we turn our attention to space. How much do you weigh in space? Neil tells us why we should be thinking about how much mass something contains instead of how much something weighs. You’ll learn why your weight in water is basically zero. Why are astronauts weightless in space? Neil explains how Sir Isaac Newton discovered orbits. Find out why most energy from a rocket launch is not used to get the rocket into space. All that, plus, we explore the science of Ad Astra, The Expanse, and 2001: A Space Odyssey.

Thanks to our Patrons Christopher Sukhanenya, Dmitry Pugachevich, Eugenio Barrera, Dakota Clifford, Nick Mancusi, Nicholas Musial, Sebastian Roser, Bryan J. Jacop, Robert Frasco, and Obumneme Ozoh for supporting us this week.

NOTE: StarTalk+ Patrons can watch or listen to this entire episode commercial-free.

About the prints that flank Neil in this video:

“Black Swan” & “White Swan” limited edition serigraph prints by Coast Salish artist Jane Kwatleematt Marston. For more information about this artist and her work, visit Inuit Gallery of Vancouver.

In This Episode

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