I'm Ben Weinstein-Raun; I work at MIRI, and am originally from Blacksburg, Virginia.

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benwr's Comments

benwr's unpolished thoughts

I made a blog because I didn’t know where else to write gushing reviews of things. I haven’t written anything there yet, but soon I hope to have written up some of the following:

  • An account of what I’ve learned since getting mildly fixated on pumping CO2 out of my bedroom
  • A gushing review of my iPad Pro 11” with Apple Pencil
  • A mostly-gushing review of my Subaru Crosstrek
  • A gushing review of my bed and mattress
  • A gushing review of the-general-excellence-of-fast-food-franchises
  • A post about how I feel a lot of internal tension about consumerism
benwr's unpolished thoughts

I’ve recently been thinking a lot about pumping CO2 out of my bedroom. By coincidence, so has Diffractor (in a slightly different context / with different goals). His post on the CO2 scrubber he built is a pretty good read, although I think he might be making a mistake about the plausibility of vacuum swing adsorption using zeolites. I wrote a comment outlining what I think is the mistake, and I guess I wanted to highlight it here in case I later want to come back and find it, and because I want more people to see it and potentially write dissenting opinions.

CO2 Stripper Postmortem Thoughts

Because the air you breathe out has much more CO2 by volume than the air you're processing (it diffuses quickly). See my comment elsewhere for a potential way around this, though.

CO2 Stripper Postmortem Thoughts

Adsorption onto zeolites is also plausible, but the issue is that it requires alternately exposing the zeolites to high air pressure and low air pressure, and high airflow is required. We can idealize a perfect CO2 stripper as a magic box that inhales air and spits it out at 0 ppm. If you want a steady-state concentration of 500 ppm for 2 people, then we can see how much air-flow is required to lock up 2 kg of CO2 in 24 hours. This comes out to about 100 cubic feet per minute. This is the bare minimum air flow for any CO2 stripper, but in this particular case, it corresponds to a 25 horsepower air compressor, which is 18 kilowatts.

I'm not sure this is as much of a barrier as it sounds, at least if you have access to a window you can vent to. Imagine if I had a membrane that let only CO2 through, and a 50-micron vacuum pump (typically 1/2 HP). I could pump CO2 out of the room about as fast as the CO2 would diffuse across the membrane. In this setup, the amount of gas pulled out would be pretty tiny, because you'd be pumping only the CO2, but the effective amount of air being processed would be quite large.

So if you have a vacuum swing adsorption machine, with some zeolites in an array of mixing chambers, that can be alternately mixed with the air in the room and then evacuated outside, what matters is the equilibrium adsorption of each component of air, and the speed of adsorption / desorption. The air mixing can be done with a simple fan (providing the effective high volumes of air processing).

That said, there are other major problems with zeolites. The main one I've been struggling with is that zeolites really love to adsorb water vapor, nearly as much as CO2, and there’s a lot more water vapor than CO2 in the air. Competition for adsorption sites isn’t well-understood, but one study shows that water vapor in the air seriously decreases the amount of CO2 adsorbed. This also means that the system described above would function as a dehumidifier as much as a CO2 pump.

[epistemic status: very uncertain; writing as though I were more certain because I think it's more fun / engaging]

The best of the www, in my opinion

My list is similar but also includes

benwr's unpolished thoughts

Doom circles seem hard to do outside of CFAR workshops: If I just pick the ~7 people who I most want to be in my doom circle, this might be the best doom circle for me, but it won't be the best doom circle for them, since they will mostly not know each other very well.

So you might think that doing doom "circles" one-on-one would be best. But doom circles also have a sort of ceremony / spacing / high-cost-ness to them that cuts the other way: More people means more "weight" or something. And there are probably other considerations determining the optimal size.

So if you wanted to have a not-at-the-end-of-a-workshop doom circle, should you find the largest clique with some minimum relationship strength in your social graph?

benwr's unpolished thoughts

Yet another Shortform-as-feature-request:

Notifications and/or RSS feeds from particular posts' comments / answers.

This would be especially useful for Questions and Shortform posts (sometimes tellingly mis-labeled "shortform feeds"), both of which are things where one particular post has a collection of related comments, and which gather content over time.

I currently subscribe to the front page in Feedly, and whenever someone asks a question that I find interesting I mentally cringe because I know that I'll have to remind myself to check back (and I probably will never actually check back).

I guess I could come up with some custom Zapier / IFTTT system for this if I spent a few hours on it, but I suspect this would be generally useful functionality.

September Bragging Thread

Update: our application was approved! The Lodge is almost certainly moving!

benwr's unpolished thoughts

One friend pointed out that you might be able to avoid some of the pitfalls by releasing something like an open source desktop application that requires you to feed it a database of information. Then you could build databases like this in lots of different ways, including anonymous ones or crowdsourced ones. And in this case it might become a lot harder to claim that the creator of the application is liable for anything. I might actually want to talk to a lawyer about this kind of thing, if the lawyer was willing to put on a sort of "engineering" mindset to help me figure out how you might make this happen without getting sued. So if you know anyone like that, I'd be pretty interested

benwr's unpolished thoughts

There should really be a system that does what WebMD tried to do, but actually does it well.

You'd put in your symptoms and background info (e.g. what country you live in, your age), it would ask you clarifying questions ("how bad is the pain from 1 to 10?" "which of these patterns is most like the rash?" "Do you have a family history of heart disease?") and then it would give you a posterior distribution over possible conditions, and a guess about whether you should go to the emergency room or whatever.

Is this just much harder than I'm imagining it would be? It seems like the kind of thing where you could harvest likelihood ratios and put them all into a big database. Is there some regulatory thing where you can't practically offer this service because it's illegal to give medical advice or something?

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