Part two of Grant Sanderson's video with Terry Tao on the cosmic distance ladder
10 comments
·February 23, 2025zokier
tbh I would love to see full length video walking through the work that Kepler did with actual numbers, to me that part remained bit unclear. Especially how to get some quantitative values out of the analysis, considering how the eccentricity of the orbits is not really something easily visually discernible.
> In principle, using the measurements to all the planets at once could allow for some multidimensional analysis that would be more accurate than analyzing each of the planets separately
(from the blog post)
I'd also love to see this idea expanded further. Intuitively it feels like adding Venus into the calculations should dramatically help constrain the orbit of Mars, but how exactly that would work out I'm not sure.
j7ake
The corrections in his blog post show you the level of precision mathematicians are used to.
A regular interviewer would have left the inaccuracies as they are because it’s too tedious to go over all of them when you have a casual conversation.
maxnoe
pavon
Note this blog post also has links to both parts of the video. (Our corporate firewall annoyingly blocks a bunch of new gTLDs, including xyz).
hakaneskici
As a side question, what's the rationale for this? Is there a list of nsfw gTLDs?
dang
Related. Others?
Climbing the cosmic distance ladder: Terence Tao book announcement - https://news.ycombinator.com/item?id=24743177 - Oct 2020 (13 comments)
Terrence Tao: The Cosmic Distance Ladder - https://news.ycombinator.com/item?id=1782398 - Oct 2010 (6 comments)
jessriedel
Note that the modern cosmic distance ladder has multiple partially independent paths using different techniques, making it more like a DAG. The wikipedia page has a nice diagram.
Gunax
This was very entertaining. I had a rough idea of the timeline before, but had never thought about it in this way (that is, a ladder).
They don't go into detail, but Cepheid stars are amazing
https://en.wikipedia.org/wiki/Cepheid_variable
Consensus mechanism for pulsation:
https://en.wikipedia.org/wiki/Kappa%E2%80%93mechanism
Basically the changes in ionization state, opacity, and temperature all influence each other, causing a cycle.