relativity

Albert Einstein in 1921. Text says Einstein's revolutionary equation about the equivalence of matter and energy E=MC2 is published on September 27, 1905
Time lapse photography by Chuttersnap on Unsplash

Why does time change when traveling close to the speed of light? 

Why does time change when traveling close to the speed of light? A physicist answers.

Image of a black hole at the centre of galaxy M87 and its event horizon, taken by the Event Horizon telescope in 2019. Photograph: Event Horizon Telescope Collaboration/EPA

Podcast Episode 23 | What is a Black hole?

What is a black hole is, what is inside a black hole including the event horizon and singularity? We talk about quasars and the big bang too.