Do you or have you ever use thought experiments to some practical end?
One of my favorites is the “ladder paradox” in special relativity, although I originally learned is as a pole vaulter rather than a ladder:
A pole vaulter is running carrying a pole that is 12m long at rest, holding it parallel to the ground. He is running at relativistic speed, such that lengths dilate by 50% (this would be (√3/2)c). And he runs through a barn that is 10m long that has open doors in the front and back.
Imagine standing inside barn. The pole vaulter is running so fast that the length of the pole, in your frame of reference, has contracted to 6m. So while the pole is entirely inside the barn you press a button the briefly closes the doors, so that for just a moment the pole is entirely closed inside the barn.
The question is, what does the pole vaulter see? For him, the pole has not contracted; instead the barn has. He’s running with a 12m pole through what, in his frame of reference, is a 5m barn. What happens when the doors shut? How can both the doors shut?
I will admit that I have never used this thought experiment for any practical end.
For those who haven’t studied relativity, this thought experiment is great at showing the “Relativity of Simultaneity”.
The only way the doors can shut from the pole vaulter’s reference frame is if they close at different times. The exit door opens and shuts first, before the tip of the pole has gone beyond it (otherwise it would hit the door, obviously), and then later, only once the back end of the pole has cleared the entrance door, does it close.
My favorite is probably Russell’s teapot, but Daniel Dennett had some good ones in the intuition pump book too.
https://en.wikipedia.org/wiki/Russell’s_teapot
It demonstrates the burden of proof is on the person making claims, including if the claim is unfalsifiable.
I was influenced greatly by Robert Axelrod’s short essay about the Prisoner’s Dilemma titled “The Prisoner’s Dilemma Computer Tournaments and the Evolution of Cooperation” (link PDF warning)
tl;dr The essay explores an iterative game of Prisoner’s Dilemma, and demonstrates how cooperation can emerge from a group of self interested participants. It has implications for the statistical emergence of morality, and even remarks on politics.
