Author Archives: The Physicist

Q: Is it more efficient to keep keep a swimming pool warm or let it get cold and heat it up again?

The original question: I’m having a debate with my wife that I think you can help us resolve.  We have a swimming pool in our back yard.  It has an electric heater, which we set to keep the pool water … Continue reading

Posted in -- By the Physicist, Engineering, Physics | 22 Comments

Q: What determines the size of the bright spot when you focus sunlight with a lens?

Physicist: This question really appeals to my ten-year-old self.  If you’ve never tried to burn something with a lens, collect three pairs of sunglasses, a magnifying lens, and something you dislike.  On a bright day, put on all three pairs … Continue reading

Posted in -- By the Physicist, Equations, Geometry, Math, Physics | 1 Comment

Q: Why are numerical methods necessary? If we can’t get exact solutions, then how do we know when our approximate solutions are any good?

Physicist: When a problem can be solved exactly and in less time than forever, then it is “analytically solvable”.  For example, “Jack has 2 apples and Jill has 3 apples, how many apples do they have together?” is analytically solvable.  … Continue reading

Posted in -- By the Physicist, Computer Science, Equations, Math | 13 Comments

Burning Man 2017

Long ago, Ask a Mathematician / Ask a Physicist was two guys sitting around in the desert talking to strangers about whatever came to mind.  It’s been a while, but we’re heading back to Burning Man for more of the … Continue reading

Posted in -- By the Physicist | 8 Comments

Q: How can something be “proven” in science or math?

The original question was: … it confuses me that abstract concepts, such as Banach-Tarski, and other concepts in pure mathematics and theoretical physics, can be considered to have been “proven”.  Is it not the case that one can only prove … Continue reading

Posted in -- By the Physicist, Conventions, Math, Philosophical | 7 Comments

Q: If time is relative, then how can we talk about how old the universe is?

Physicist: One of the most profound insights ever made by peoplekind is that time is relative.  This isn’t some abstract idea, mistake, or mathematical artifact.  If you have two identically functioning clocks, you can start them together, move them to … Continue reading

Posted in -- By the Physicist, Astronomy, Physics, Relativity | 61 Comments