Author Archives: The Physicist

My bad: If fusion in the Sun suddenly stopped, what would happen?

Physicist: A commenter from the original post was kind enough to point out a massively bone-headed mistake.  My bad.  In the calculation to figure out how long it would take the Sun to cool I had used Fourier’s law of … Continue reading

Posted in -- By the Physicist, Mistake | 14 Comments

Q: If fusion in the Sun suddenly stopped, what would happen?

Physicist: Almost nothing.  We’d have plenty time to pack our bags and leave. Assume that the cause of the fusion-stopping doesn’t matter, maybe the Weak force suddenly changed, or maybe the Vorgons used the Tax Uthat on the Sun, or … Continue reading

Posted in -- By the Physicist, Astronomy, Physics | 11 Comments

Q: Does opening a refrigerator cool down the room?

Physicist: Briefly yes, or no, not at all.  If you think of the room as including the inside of the refrigerator, then opening the door does nothing.  Otherwise, it does almost nothing.  But ultimately, if you leave the door open … Continue reading

Posted in -- By the Physicist, Engineering, Entropy/Information, Physics | 33 Comments

Q: What is the probability of an outcome after it’s already happened?

Physicist: There are a lot of subtleties to this.  Reading the question, your gut reaction should be “Duh, it’s 100%!  Wait, is this really a question?”. And yet, there are many times in which you may find yourself estimating probabilities … Continue reading

Posted in -- By the Physicist, Philosophical, Probability, Quantum Theory | 11 Comments

Q: Why are the days still longer than nights, until a few days after the fall equinox?

Physicist: The issue here is the equinoxes are the two days of the year when the length of the day should be exactly as long as the night.  And yet you’ll find that on the equinox the day is always … Continue reading

Posted in -- By the Physicist, Astronomy, Physics | 2 Comments

Q: What is a Fourier transform? What is it used for?

Physicist: Almost every imaginable signal can be broken down into a combination of simple waves.  This fact is the central philosophy behind Fourier transforms (Fourier was very French, so his name is pronounced a little wonky: “4 E yay”). Fourier … Continue reading

Posted in -- By the Physicist, Equations, Math | 40 Comments