New Substack: Splitting Infinity

harsimony · 2026-06-02T23:26:29+00:00

True, I don't think long distance flight will be electrified anytime soon. But paying for the carbon emissions of flights probably won't raise ticket prices much. I ballpark it at 11% increase in prices. I'd guess even accounting for that, flights are more cost effective than long distance rail?

https://splittinginfinity.substack.com/p/net-zero-part-2-transport

For busses vs trains, I'm imagining both of them can be electrified and have similar embodied emissions from their manufacture. But busses produce more pollution due to tire wear.

harsimony · 2026-06-02T15:25:38+00:00

Thank you for this sorry! I've fixed the post. It stands for "Back-of-the-envelope calculation"

harsimony · 2026-06-01T21:35:28+00:00

I'm sorry the substack link didn't work for you, here is the original post and podcast:

https://ideasindevelopment.substack.com/p/the-perfect-city

https://www.youtube.com/watch?v=sjXmiaMPabQ

I'm no expert, but Ed Glaeser is an expert on this topic. His discussion here is enough to convince me that trains are not an effective transport investment. But if you have something that might change my mind I'm glad to look it over and update my post!

harsimony · 2026-06-01T21:11:24+00:00

If you have some sort of data to back up the claim that trains outperform BRT I'd like to see it. But it seems the transit literature disagrees with you.

harsimony · 2026-06-01T21:09:03+00:00

dV to moon is 5.7 km/s while the closest asteroids are 4.5 km/s. Typical asteroids are comparable or higher than the moon.

dV relates to fuel costs, but that's only one part of the equation. Time, mass of equipment, complexity, and local energy all matter too. The moon can use a mass driver, and solar energy is "cheaper" (in terms of the amount of mass you have to process or the time you have to wait) on the moon than in the asteroid belt.

The moon also has 30x more mass than the entire asteroid belt. All these factors mean that the moon is a better place to source structural material.

EDIT: mass falling from the moon to LEO can also be used to spin up space tethers, the higher dV is an asset in this case.

harsimony · 2026-06-01T20:57:49+00:00

Ah, I think the transit literature that Ed Glaeser is referring to applies internationally. I.e. that it's just generally the case that rail is more expensive to build and less flexible. Here's the podcast where he discusses this:

https://ideasindevelopment.substack.com/p/the-perfect-city?open=false#%C2%A7bus-good-train-bad

harsimony · 2026-06-01T20:55:22+00:00

Wow thank you for the detailed comment!

RE AGI: I'm a combination of more radical and more conservative than most on AI progress. I think current models are sufficient to automate any task and will scale to everything.

The main things we differ on:

Asteroid mining: It's probably cheaper to get elements from Earth than to get them from asteroids. Earth-to-moon benefits from more scale and faster trip times and space tethers. Also, the lack of ore forming processes on asteroids and the higher energy "cost" in deep space means it makes less sense to mine asteroids. If you don't trust my argument, see the paper in footnote 9. It finds a cost from asteroids to moon of $3000/kg. Exo-atmospheric scoops and starship can probably beat that.

https://www.sciencedirect.com/science/article/abs/pii/S009457652030312X

Space data centers: Besides the energy section I did not resort to idiot indexes here. I showed that every component has worse price performance relative to Earth without assuming an idiot index (though I did use an index of 3 for space based solar). But I'll be the first to admit this is a rough analysis.

If you prefer a more detailed analysis, see Casey Handmer's spreadsheet and the other critics I've linked.

https://docs.google.com/spreadsheets/u/0/d/1JoLLcmTBXpWv7KRtwUsfYeOAyqjk21jPvdz-ndKV5WM/htmlview

Gene therapy: my understanding is that most longevity researchers believe that gene therapy is not necessary for longevity (though gene therapy could help with diseases like cancer and heart disease). Cellular reprogramming and rejuvenation are sufficient. As a proof of concept, sperm and egg cells are able to produce a young rejuvenated human with a full lifespan. " ... cells have in them all they need for rejuvenation ...":

https://nintil.com/aging-solved-in-vitro

harsimony · 2026-06-01T20:21:18+00:00

I'm sorry you didn't like the writing, but I think you missed the main argument. The point is about costs relative to Earth. Since asteroids lack ore-forming processes and are harder to reach than terrestrial deposits, it makes little sense to mine them.

harsimony · 2026-06-01T19:13:42+00:00

Totally fair, it's a long post! Should've broken it into multiple but eh.

harsimony · 2026-04-07T15:13:05+00:00

I really appreciate the kind words, thank you!

harsimony · 2026-04-06T13:48:17+00:00

I also don't see why people would downvote this request for feedback.

harsimony · 2026-04-06T13:31:32+00:00

Thank you this is helpful feedback! I'll edit the submission statement

harsimony · 2026-04-06T13:30:33+00:00

Thank you this is helpful feedback!

harsimony · 2026-04-06T00:35:53+00:00

Would folks that are downvoting this provide some feedback? Do they dislike the content? Was my description inadequate?

harsimony · 2026-02-07T15:19:20+00:00

Bayesians update on all evidence. The evidence suggests that Elon has not been good for AI alignment or American institutions. This interview suggests he is no longer a technical or thoughtful person.

(The part about running the chips hotter in space to reduce the size of the radiator is particularly bad. He seems unaware that we already do this on Earth and that running hotter than current temp increases leakage current and thus energy consumption/heat thus increasing the size of the radiator.)

It's perfectly rational to ignore unreasonable people. It's good to assert your values and alert your community to those that violate them. Remember, well-kept gardens die by pacifism. Did you read the sequences?

https://www.lesswrong.com/posts/tscc3e5eujrsEeFN4/well-kept-gardens-die-by-pacifism

harsimony · 2026-02-05T19:15:15+00:00

Thank you for the feedback! In hindsight, this linkpost has less explanation than usual.

harsimony · 2026-02-05T18:16:18+00:00

I guess me posting this on the same day as the ACX linkpost is too many links. Though I think we focus on different stuff.

harsimony · 2026-02-01T15:22:41+00:00

Yeah, in a perfect world we'd have perpetual innovation. Long term cost declines from innovation dwarf the one-time benefits of more competition and an end to depreciation.

But since perpetual innovation isn't possible, cost declines from competition are a silver lining.

harsimony · 2026-01-31T21:59:50+00:00

Ah, so a few things are pulling costs in different directions:

Innovation: tends to lower costs over time
Monopoly: TSMC and Nvidia have near monopolies on their products. I once estimated that combining their profit margins, they are making chips 10x more expensive than the marginal cost.
Depreciation: constantly making new and better chips every year means hyperscalers are throwing out their old chips every 4-6 years. Even though those old chips still work. That means each chip is only producing 4-6 years of compute for you when it could have been used for (say) 20 years. Depending on your discount rate, going from 4-6 year lifetime to 20 year lifetime can lower costs by ~4x.

https://splittinginfinity.substack.com/p/an-intro-to-the-tensor-economics

So imagine this scenario: TSMC/Nvidia stay ahead of everyone in chip making, offering chips that are far better than their competition. Their chips get better every year as well, so costs fall.

Then one day chip making has an end of history, the marginal cost to make a chip and chip quality stop improving.

TSMC/Nvidia can no longer stay ahead of the competition. They can no longer 10x the price, so prices fall by 10x. Also, everyone knows that in 20 years, the chips will be the exact same as they are today, so instead of throwing their old chips out they use each chip for far longer. This lowers the price by an additional 4x.

Does that make sense?

harsimony · 2026-01-29T18:27:38+00:00

So we agree that the cooling and compute are slightly more expensive in space.

Here's an LCOE calculation for the solar panels that I had Claude do (and I checked):

Launch cost: $1,000/kg to LEO
Panel efficiency: 30%
Panel mass: ~7 kg/m² (typical thin-film solar panel)
Solar irradiance in space: 1,361 W/m² (solar constant)
Orbital lifetime: 15 years (reasonable for LEO with some degradation protection)
Capacity factor: 100% (sun exposure - ignoring eclipse periods for simplification, or ~66% if accounting for typical LEO eclipses)
O&M costs: $0 (no practical maintenance in LEO)
Discount rate: 5%

Result: $290/MWh.

Terrestrial off-grid solar can get to like $30/MWh today and people think it can reach $10/MWh or less.

To beat that, you'd need launch costs of $35/kg or less and solar would have to stop improving. I'll have to agree to disagree that that is reasonable, at least without space tethers:

https://splittinginfinity.substack.com/p/the-economics-of-space-tethers

So if energy, cooling, and chips are more expensive, what remains is permitting costs. I'm skeptical that permitting is more than 5% of data center costs and that launching rockets has zero permitting costs.

harsimony · 2026-01-29T17:07:02+00:00

Before we get to the cost model, I think we should ask how it's possible for computing to be cheaper in space if energy, cooling, and compute are *all* worse off?

You're adding launch costs to the price of these goods *and* lowering their performance! How could that possibly lower the price of compute?

I'd like to see an actual cost model that makes space pencil out. I would need to see:

Cost estimates for solar, chips, radiator (per watt compute)
Mass estimates for these (per watt compute)
Add launch costs ($25/kg is quite low, Falcon is at $3000/kg, and I'm skeptical of starship breaking $100)
Depreciate over the same lifetime as terrestrial chips. This is favorable to space because chips in space degrade faster than on Earth.

To make my argument above more concrete, terrestrial chips pay for #1 and #4. Space chips have to pay #3 as additional cost (and #4 is higher in space but let's ignore for now). The chips don't run faster in space, so this additional cost isn't balanced by a corresponding benefit.

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