Six Science Posts - #77

ChatGPT's power use, lunar luminaries, a stoic view of computing and more

Author

Harshal Chhaya
June 16, 2025

Six tweets that celebrate engineering and all things STEM.

To my new friends on this list, welcome! I scroll so you don’t have to.

I have some comments on a few of the posts.

If there’s one that you particularly like, let me know.

And please forward this email to other curious folks who might also enjoy staying informed.

#1 🤯 

Sam Altman wrote an essay recently where he says that “a ChatGPT query uses about 0.34 watt-hour, about what an oven would use in a little over one second”. I find this information useful.

This number doesn’t include the energy used to train the models - which is a one-time massive investment.

This number is also comparable to Google’s last published estimate (2009) of 0.3 watt-hours per search, including the energy to build and run the system. (source: @pitdesi on X)

Sam’s essay is at https://blog.samaltman.com/the-gentle-singularity 

#2 🤯 

😆 

#3 🤯 

Lunar luminaries! 🫡 

#4 🤯 

Very stoic vibes. And very true too.

#5 🤯 

And then 8.5 min to get to Earth where it helps make a shadow

#6 🤯 

About

This newsletter is my way of sharing interesting science-related news with my curious friends. I enjoy finding science and math connections in our world.

Please share this newsletter with others. Let’s encourage curiosity.

- Harshal (@hschhaya on X/Twitter)

This is issue #77.

  • Seventy-seven is the smallest positive integer requiring five syllables in English.

  • 77 is first of the (7.q) semi-prime family, where q is a higher prime

  • 77 is the sum of three consecutive squares, 42 + 52 + 62

  • 77 is the sum of the first eight prime numbers

  • During World War II in Sweden at the border with Norway, "77" was used as a shibboleth (password), because the tricky pronunciation in Swedish made it easy to instantly discern whether the speaker was native Swedish, Norwegian, or German.

  • 77 is the atomic number of Iridium - symbol Ir. This very hard, brittle, silvery-white transition metal is considered the second-densest naturally occurring metal (after osmium) with a density of 22.56 g/cm3 (0.815 lb/cu in) as defined by experimental X-ray crystallography.[a]

    • One of the first projects to cover the Earth with internet access was named Iridium because it planned to use a constellation of 77 satellites.

That’s it for this issue.

Hit ‘reply’ to tell me what you think.

And hit ‘forward’ to share with your friends and family.

Let’s all celebrate science and engineering and curiosity.

Best wishes,

Harshal