Things I Mean to Know

Here is the latest episode of This American Life:

630: Things I Mean to Know
Oct 27, 2017
There are so many facts about the world that we take for granted — without ever questioning how we know them. Of course the Earth revolves around the sun. Of course my dog loves me. But how exactly do we know things like that are true? This week, stories of people trying to unspool some of life’s certainties, and what they find.

It opens with a college girl who was upset that she knew that the Earth went around the Sun, but when challenged, she could not present any evidence for it or explain why that is true.

If you ask ppl to name some scientific fact that is known for sure, you are likely to hear the Earth going around the Sun.

Astronomy, Physics, and other science educators have done the public a disservice.

Motion is relative. Whether the Earth goes around the Sun, or vice versa, depends on your frame of reference. The Sun is much larger, so for various technical reasons related to inertia and gravitational forces, cosmological models are simpler with a Sun-based frame. Unless you are modeling the Milky Way, in which the Sun goes around the giant black hole at the center. Or if you are modeling communications satellites, where it is much simpler to use an Earth-based frame.

So why is everyone so sure about a scientific fact, when it is really just a convention for the mathematical convenience of astronomers?

The story also mentions the fact that the Earth is round. It is not perfectly round, but it is approximately round and certainly not flat. Yes, that is a valid scientific fact.

There are lots of scientific facts. So why do so many ppl focus on the Earth going around the Sun? My theory that it is all Galileo anti-Christian propaganda.

The idea is that Europe suffered centuries of darkness because Aristotle and the Pope said the Sun went around the Earth, and no one was allowed to question it. Then Copernicus and Galileo bravely said that the emporer had no clothes, and a scientific revolution brought knowledge, liberation, and prosperity to all. Nice story, but ridiculous. The Pope's position was closer to what we now consider the scientific truth.

Another example in the story is human menstrual synchronization. This was supposed proved by some research done by women, and women commonly believe it. But the research has not been replicated in the more careful studies done by men. See Menstrual synchrony for details.