3.8M views · Jan 26, 2023 · 21:56 · 1 HN recommender · 3 mentions · discussed 2023–2025
PBS Space Time considers whether life could be based on silicon instead of carbon, comparing the two elements' chemistry and why silicon is the most plausible alternative.
Why Hacker News points people here: Recommended as a solid, informative treatment of silicon-based life and the chemical limits on alien biochemistry.
“PBS Space Time has a very good & informative episode covering this.”HN comment, 2025
“PBS Space Time has a very good & informative episode covering this.”
Why silicon is the next likeliest basis for alien life.
PBS Space Time has a very good & informative episode covering this. I'll try to dig it up. Most elements are missing some key properties that carbon has. Silicon is the next most-likely element, but it's still missing out on a few properties that carbon has. Here: link Or on YouTube: this video
“chemistry is not infinitely complex.”
Silicon-based life possibilities are limited by real chemistry.
It is a fun thought, but chemistry is not infinitely complex. Much like the Fermi paradox, once you start applying real world qualifiers on chemistry of complex life the search space becomes quite small. this video Life inside of stars does enable different options.
“There are very few atoms that allow for the complex scaffolding for shapes.”
Silicon-based life and its bonding limitations.
PBS Space Time: What If Alien Life Were Silicon-Based? this video There are very few atoms that allow for the complex scaffolding for shapes. Many atoms are too large (and thus bond too weakly). Silicon is interesting, but it has some difficulties. link > Silicon–oxygen single bonds are longer (1.6 vs 1.4 Å) but stronger (452 vs. about 360 kJ mol−1) than carbon–oxygen single bonds. It is much easier to lock up oxygen and silicon in SiO than in CO compounds and in turn makes them less available for more complex structures of life.
