Coins, Dice, and Entanglement

As a kid I loved multiplication. Dividing was hard—because I didn’t know what to do if the remainder wasn’t zero—but I managed to do okay in my tests. It was only in high school that I met the Cartesian product. Tensor products had to wait till my undergrad. Mathematics is full of products: scalar product,…

Is Gravity Weakening?

Some physicists believe gravity is weakening. If true, then Earth won’t hold gases in its atmosphere. Lighter gases, like oxygen, will escape, and life on Earth will end. Robert H. Dicke predicted that gravity weakens by about 0.2% every year (I'm skeptical about this estimate). It must weaken by more than 90% for oxygen to…

Stargazing: Seeing the Past

Stargazing is a lovely hobby—if you live in a place where you can see the stars, that is—but what you see is the past. Einstein’s relativity theory postulates that nothing can travel faster than light. To understand why you see the star in the past, let me give an analogy. Imagine times where kingdoms had…

On Steven Weinberg (1933-2021)

https://podcasters.spotify.com/pod/show/sriram-akella2/episodes/Steven-Weinberg-1933-2021-voice-by-11-ai-e2h5bgq On 23rd July this year, we lost Steven Weinberg. He was the recipient of the 1979 Nobel Prize in Physics (along with Sheldon Glashow and Abdus Salam) and a professor of physics and astronomy at The University of Texas at Austin. Weinberg was a prolific writer, publishing in periodicals like The New York Review…

Popper and Reverse Motion Pictures

https://podcasters.spotify.com/pod/show/sriram-akella2/episodes/Popper-and-Reverse-Motion-Pictures-voice-by-11-ai-e2gvs0l Imagine watching an action film like The Tomorrow War in reverse. Or imagine a tree shrinking back to a seed. Or a broken cup rearranging itself into an unbroken cup. Magic, isn’t it? But not everything is irreversible. Imagine a car going straight. If we capture this in a film and run it in…