Instant stone (just add water!) 2019-11-13T22:33:39.903Z · score: 74 (29 votes)
Iron: From mythical to mundane 2019-10-24T22:43:45.898Z · score: 21 (8 votes)
Turning air into bread 2019-10-21T17:50:00.117Z · score: 87 (39 votes)


Comment by jasoncrawford on Instant stone (just add water!) · 2019-11-15T21:45:57.281Z · score: 1 (1 votes) · LW · GW

The Venus figurine you linked to is interesting. I knew there were carved figurines that old but not fired ceramic. Maybe Courland is wrong, or maybe he's just talking about kilning (presumably this figurine, dating from over 27 kya, would have been fired on a campfire, not in kiln).

In any case, I wouldn't call the figurine pottery, so maybe what I wrote is still technically correct?

Comment by jasoncrawford on Instant stone (just add water!) · 2019-11-15T21:40:21.303Z · score: 1 (1 votes) · LW · GW

According to Concrete Planet, by Robert Courland, the archaeological site at Göbleki Tepe, c. 9600 BC, shows evidence of lime products (plaster, mortar, and/or concrete). Fired-clay figures (not even pottery) don't show up until Nevali Çori, c. 8600 BC. At least, according to the table on p. 48. On that same page he says that “fired ceramics make an appearance soon after the invention of the limekiln.”

Comment by jasoncrawford on Instant stone (just add water!) · 2019-11-15T17:06:15.274Z · score: 3 (2 votes) · LW · GW

Not totally unrecyclable. You can crush concrete and re-use it as aggregate for other concrete, I think.

Not sure if you can re-kiln it to extract fresh lime, but that seems possible in principle. Might just not be worth it right now, given the availability of limestone deposits.

Recycling is not always better than alternatives, it's just one option among many. If the economics don't make sense then there's no reason to do it.

Comment by jasoncrawford on Turning air into bread · 2019-10-30T21:29:23.247Z · score: 5 (2 votes) · LW · GW

Agree. We have barely scratched the surface, literally, of one planet in one solar system. We use a tiny percentage of the energy from the one star closest to us. The amount of mass and energy available to us is so many orders of magnitude beyond our current usage that in discussing 21st-century industrial policy it's effectively infinite.

Comment by jasoncrawford on Turning air into bread · 2019-10-30T18:45:22.846Z · score: 5 (2 votes) · LW · GW

Do you see any downsides at all to “slowing down”?

How do you weigh those against the risks you're foreseeing?

Comment by jasoncrawford on Turning air into bread · 2019-10-29T21:36:39.655Z · score: 15 (6 votes) · LW · GW

Why do you find it unsatisfying? (Personally, I find it immensely satisfying.)

Why do you place a moral stigma against technological solutions to the problems of life and survival? What do you think we need to “repent”? Why do you say we “got away with it”, instead of, “we solved it!”

Why do you “imagine” we won't continue to find new solutions to problems? Especially when we've already found so many, for many generations? Why make an argument from failure of imagination, rather than from history?

Comment by jasoncrawford on Iron: From mythical to mundane · 2019-10-29T21:30:43.774Z · score: 3 (2 votes) · LW · GW

Yup, aluminum is even more abundant in the Earth's crust than iron; about 8% vs. 5%. But it requires electricity for smelting and so wasn't common until the very late 1800s or so

Comment by jasoncrawford on Iron: From mythical to mundane · 2019-10-29T21:29:44.748Z · score: 5 (3 votes) · LW · GW

It's more the other way around: Iron with more than ~2.1% carbon is brittle, and therefore it cannot be worked with tools; it can only be cast—so it's called “cast iron”. The low-carbon iron can be worked with tools, hence “wrought”.

It's the smelting process that results in the carbon content: smelting at temperatures high enough to melt the iron, also causes it to undergo a phase change that causes it to absorb more carbon.

Comment by jasoncrawford on Open & Welcome Thread - October 2019 · 2019-10-17T01:06:29.063Z · score: 46 (17 votes) · LW · GW

Hi everyone. I've discovered the rationality community gradually over the last several years, starting with Slate Star Codex, at some point discovering Julia Galef on Twitter/Facebook, and then reading Inadequate Equilibria. I still have tons of material on this site to go through!

I'm also the author of a blog, The Roots of Progress (, about the history of technology and industry, and more generally the story of human progress.