Whilst the LEDs are not around the corner, I think the Kr-Cl excimer lamps might already be good enough.
When we wrote the original post on this, it was not clear how quickly covid was spreading through the air, but I think it is now clear that covid can hang around for a long time (on the order of minutes or hours rather than seconds) and still infect people.
It seems that a power density of 0.25W/m^2 would probably be enough to sterilize air in 1-2 minutes, meaning that a 5m x 8m room would need a 10W source. Assuming 2% efficiency that 10W source needs 500W electrical, which is certainly possible and in the days of incandescent lights you would have had a few 100W bulbs anyway.
EDIT: Having looked into this a bit more, it seems that right now the low efficiency of excimer lamps is not a binding constraint because the legally allowed far-UVC exposure is so low.
"TLV exposure limit for 222 nm (23 mJ cm^−2)"
23 mJ per cm^2 per day is just 0.002 W/m^2 , so you really don't need much power until you hit legal limitations.
Meta-lesson: don't do drugs
It's physical size, permanence (lasts for 200+ years with extensions possible) and cost per unit area (cheap enough for middle class people), safety, no sea motion, pleasant land to live on, strong foundations for large buildings, robustness (not sensitive to one small mistake)
You don't need to produce food, you don't even need to produce physical goods. But you do need a population of 1 million people who are there permanently and call it home.
Seasteading, which means making new land at scale
If you care about creep, ice at -20 C shouldn't have >1 MPa on it.
So what is your criterion for caring about creep? How does it vary with temperature? From the limited reading I have done it looks like you basically eliminate creep in practice at -100°C and you can put something like 30MPa on ice.
But I am not clear how sawdust/fiber affects this.
Here is a paper with "concrete" that has 800 MPa compressive.
Sure, but this material is presumably impractical. Practical, cheap concrete seems to be in this 20-40 MPa bracket.
But really, I don't think this idea is particularly limited by the compressive strength of ice. I think the biggest threat is creep of the ice under load, and the difficulty of making an upper layer that covers the ice with good strength and also low thermal conductivity, and is also cheap at huge scale. I think it's doable but it looks like this is the hard part.
Title changed from
"Architects of Our Own Demise: We Should Stop Developing AI"
to
"Architects of Our Own Demise: We Should Stop Developing AI Carelessly"
Yes I get that the increase in tensile strength is probably going to be proportional to the percentage of fiber added, but there's no need to go to 14% just because that was the original pykrete formula. Maybe you only need 1/3 of the strength. Or maybe limiting creep is more important. Or maybe you just want to make it less brittle.
I just haven't got the data for the properties of pykrete at lower temperatures and I don't understand how it affects creep rates.
Since the water is almost free you might be able to choose between X meter thick pykrete or 3X meter thick 1/3-strength material.
I also don't fully understand understand what properties you're actually going to need.
The insulation may also be a type of concrete with foamed glass as the solid and a cement to fill the voids. This will then be topped with a much stronger layer of concrete. That concrete can be built on. Additionally that top concrete layer can be hollow for added strength and insulation. Think of a square grid of cells for the strength layer and a solid insulation layer underneath of the foamed glass ultralight concrete.
If you want to build a heavy building it may be better to just thicken that concrete topping layer than to penetrate into the ice, as the ice will be very cold (say, -40 degrees C) and you don't want to melt it. But Maybe there are special materials that will allow this to work. Certainly NOT metals though.
https://www.sciencedirect.com/science/article/abs/pii/S2352710223008562
14% may be too much for this. You may get most of the relevant benefits at 5%.
Most importantly, you can't get stuff collected for free, or shipped for $10.
Well, shipping and collection may scale better for large projects. Shipping via ocean is $10/ton for 4000 miles but it may be possible to knock that down in a large operation.
Rice husk and/or straw may be perfect after some processing/shredding.
Also there might be other ingredients that are beneficial on a cost/utility basis, such as basalt fibers, shredded plastic waste, etc.
Since a few people have mentioned the Miller/Rootclaim debate:
My hourly rate is $200. I will accept a donation of $5000 to sit down and watch the entire Miller/Rootclaim debate (17 hours of video content plus various supporting materials) and write a 2000 word piece describing how I updated on it and why.
Anyone can feel free to message me if they want to go ahead and fund this.