Summer of Math Exposition

When you initially explained the tunnel paradox, you haven’t mentioned anything about the doors. Without the doors it’s not very obvious what the paradox is. One could accept that from one reference frame you see big train not fitting into small tunnel and from another reference frame you see small train fitting into big long tunnel. It doesn’t seem that different from accepting that each observer sees time and length contraction for the other one, or the train sees tunnel going backwards while tunnel sees the train moving forwards. All these things will be just hand-waved as “relativity”. When you tell that there are doors that close when the whole train is inside, you can then pose the question why doesn’t the train crash into the doors from it’s perspective. You have now physical event happening, and no matter what reference frame you are looking from, things can’t go trough things. The time element here is important.

Also, small detail, but I probably zoned out for a second or missed the explanation of green line in diagram, and I was confused why it moved up and down. I’ve wrongly assumed the green line is the train. It would help the visuals if the green line was infinite - it would be clearer that you are just visualizing the intersection in spacetime diagram as you are talking about things. I would give you bonus points if the segment between the two blue lines was highlighted by thick blue line-segment above the green light. It would provide nice visual of the train moving from the left to the right as you change the time.

Very interesting presentation via desmos for understanding special relativity,

I am a PhD student in numerical relativity and have therefore seen a lot of explanations about the Lorentz transformation. I was skeptical at first when I realized you are just showing some Desmos files without much text, equations, labels etc. but it turned out quite nice and some of the shown examples I have never seen before! I therefore might use some of your Desmos files in my tutorials. As an explainer for unexperienced students it might however be easier if you give some introduction to the Lorentz transformation and provide more diagrams, text, equations outside of Desmos.

You do a great job using the spacetime diagrams to show off features of the Lorentz transformation. But you never actually define the Lorentz transformation. It would also be really helpful when you first explain the spacetime diagrams to have an animation showing some objects moving along a line and the associated diagram.

Great. No frills but a very lucid visual explanation.

Thanks for this episode. Your Ranking score is an average of these individual scores: Motivation: 9 Clarity: 7 Novelty: 4.3 Memorability: 5