Is Mars Habitable? (1907)

It's really interesting how he constructs a self-consistent narrative with half true and half false premises.

For example, he totally whiffs on the geology due to bad starting premises. At this time, the Earth was believed to be relatively young (on the order of millions of years) because simple calculations would show that even a very high initial temperature would have cooled to at most the surface temperature within that time. What they missed was the internal heat budget of the planet, which we now know is driven by radioactivity (which, in 1907, had just been discovered - the Curies had shared a Nobel for it in 1903).

Wallace was right that this is a very small contributor to Earth's surface temperature, but the false assumption that the planet had dramatically cooled was behind the idea that continental shapes and faulting were due to the movement of a cooling and thus contracting planet. Plate tectonics was a few years away from even being proposed as a serious theory at this point, and it wouldn't gain much traction for another fifty years after that. But it turns out that tectonics is responsible for a lot of the geographic differences between the three bodies under discussion here. Earth has plate tectonics today, Mars probably did early in its history but does not today, and the Moon never did.

Yet despite being totally wrong about this, Wallace is correct (as best we currently understand it) that the Martian valleys are indeed fault lines. He comes around to it from a totally wrong direction: that Mars, being smaller than the Earth, began with less heat, and that its interior solidified first, causing its surface to contract onto that rigid surface and crack in a way Earth's did not.

There's a lesson here in the ability to form consistent, empirical, wrong theories given even slightly wrong inputs.

There was an interesting more recent article on life on Mars from idelwords. https://idlewords.com/2023/1/why_not_mars.htm

Not proposing little green men who are unlikely but suggesting there may be bacteria like organisms underground which seems quite possible. A reason I think Musk shouldn't be allowed to build a human settlement there in a hurry. It should be more like a national park with no biological humans. We can always have robots and FPV goggles for the visitors.

(1000+ comments on HN https://news.ycombinator.com/item?id=34213549)

A commendable effort to preserve history.

Chapter VI has an irritating equation that claims the fourth root of one-hundredth equals one-sixth. It should be obvious even without the help of any computing aid that this is wrong. Was it a typo or what else may have led to that mistake?

I don't think a whole lot of the Earth is actually habitable to begin with ;)

Wow, a fantastic work. Thanks for posting it.

This post is a bit difficult to understand.

100^(-1/4) is not 1/6. It's closer to 1/3.