Author, The Roots of Progress (rootsofprogress.org). Previously: co-founder & CEO, Fieldbook; engineering manager at Flexport, Amazon and Groupon

jasoncrawford's Comments

Were vaccines relevant to 20th century US mortality improvements?

Fair enough. Again, I don't know if it's 10%—could be more or even less.

The rest, I think, is mostly from antibiotics, and maybe general hygiene.

The history and causation here is nuanced and difficult. E.g., tuberculosis was basically solved by antibiotics—*but*, it was also declining for many decades *before* that. And I'm not sure if anyone really knows why. Hand-washing? Better diet? Less spitting in the streets? (I'm not kidding, there were actually campaigns to get people to spit less, although I'm not sure if they worked.)

Anyway I'm still researching all this.

Were vaccines relevant to 20th century US mortality improvements?

I don't know, that's what some random anti-vaxxer on Twitter claimed. I'm still doing the quantitative investigation. My point is, even if that's true, it's misleading in isolation, and arguably cherry-picked

Instant stone (just add water!)

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?

Instant stone (just add water!)

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.”

Instant stone (just add water!)

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.

Turning air into bread

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.

Turning air into bread

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

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

Turning air into bread

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?

Iron: From mythical to mundane

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

Iron: From mythical to mundane

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.

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