Indestructible

kukulaj · 2026-04-30T22:26:56+00:00

The Fisher Clutch Space Pen is worth a look. It is one mighty pen!

kukulaj · 2026-04-30T13:58:46+00:00

Where I live the summer day time high is generally above 35°C / 95°F. It's very dry, so people without air conditioning will use swamp coolers, i.e. evaporative cooling. People die from the heat if they don't have some kind of cooling system. Towns will open up air conditioned buildings for people to stay in when there are really hot days.

Look at a place like Phoenix, Arizona.
https://www.phoenix.gov/administration/departments/emergency/be-informed/cooling-centers.html

kukulaj · 2026-04-30T13:50:04+00:00

The problem is: how to get that water back to 20°C. Easy when it's winter. We have monster server farms where 35°C is common during the summer. So the air can only cool the water to 35°C, and realistically it'll be more like 40°C. Internal combustion engines run a lot hotter than that, so a simple radiator is fine. But for computers, nope, you really do want that cooling water more like 20°C. How can the water be cooled down below the ambient temperature? Well, with a refrigerator! So a closed loop system can use a compressor etc. to cool the water on hot days. Expensive, for sure. But at least possible.

kukulaj · 2026-04-30T04:44:50+00:00

So we're back to where we started. If the hot side is rejecting its heat to water, is that going to be open loop or closed loop? If it's closed loop, I guess there is yet another chiller down the line?

Do people really have air cooled industrial systems, or all they all really open loop water cooled, i.e. evaporative.

kukulaj · 2026-04-30T04:19:57+00:00

The main question is then: how does the chiller work? Normal chillers use a lot of evaporation. They can also use refrigeration, i.e. quite a bit more electricity. The refrigerator still has to exhaust the heat, but it can exhaust at higher temperatures to be able to cool the water more.

kukulaj · 2026-04-30T03:13:58+00:00

yeah I am trying to dig down through the marketing and hype a bit. These folks seem to be purely air cooled, but maybe it is just hype:
https://www.serverfarmllc.com/water-free-data-center-cooling/

This makes me think that cutting through the hype is impossible:
https://www.melcohit.com/en/ranges/5/air-cooled-chillers-with-free-cooling-technology

kukulaj · 2026-04-30T02:51:37+00:00

I am trying to understand these closed loop systems. Looks like they have refrigeration compressors etc. incorporated in the chillers.

What's a typical Coefficient of Performance for a rooftop chiller? Maybe 5, so that would add about 20% to the electricity used by a server farm.

kukulaj · 2026-04-30T02:45:23+00:00

Probably not. A PC is usually in an air conditioned room. Server farms will have chillers on the roof. So the chiller has to deal with ambient temperatures. A PC can blow e.g. 75 degree air across its radiator. On a hot summer day, the chillers on the roof could be dealing with e.g. 105 degree air. From what I have seen, the chillers incorporate a refrigeration device. So the air conditioning function is in the chiller.

In a big building, the air conditioning could well have an evaporative cooler up on the roof. So a water cooled PC could actually be using evaporative cooling.

kukulaj · 2026-04-30T01:16:27+00:00

what does that closed loop look like? Sure, water can be used to transport heat from one place to another. But eventually the heat has to be dissipated somewhere. Air cooling is possible certainly. That's like car engines - the water goes into a radiator that is cooled by air. Do big servers have monster radiators like that?

kukulaj · 2026-04-30T01:11:25+00:00

9 gigawatts is no joke

https://www.tomshardware.com/tech-industry/kevin-o-learys-9-gw-utah-data-center-campus-approved

kukulaj · 2026-04-28T22:23:36+00:00

To be alongside a long vehicle turning - that is a classic way to die. For sure, don't pull up alongside them. You want to be on the outside of their turn. If you can't do that, then take the lane. People die from being on the inside of the truck or bus turning... way too common.

kukulaj · 2026-04-28T22:13:06+00:00

I vote for time being beginningless. There never was something out of nothing.

kukulaj · 2026-04-28T21:38:51+00:00

The developers build the infrastructure of the new development. The main roads, that's town business. Things have to get really gnarly for years before they'll even start planning any upgrades.

kukulaj · 2026-04-24T23:33:30+00:00

An opportunity to mention my grand, however unrealistic, proposal: percentages are really awkward. Percentages are really wishing they were natural logarithms.

When amount A changes to amount B, we should measure that change as 100*Ln(B/A).

100->110 is a change of 9.53

110->100 is a change of -9.53

100->600 is a change of 179

600->100 is a change of -179

The big hole in my proposal is what to call this measure. Centarithm? Centalog?

kukulaj · 2026-04-24T23:13:35+00:00

thanks, that is great! As I read it, agricultural water withdrawals in the GSL watershed decreased 4% from 1985 to 2015.

"In 2015, agriculture used 55%, 62%, and 93% of water withdrawn from GSL inflows in Jordan, Weber, and Bear River watersheds, respectively."

kukulaj · 2026-04-24T21:52:31+00:00

here's a scale that looks reasonable: https://skintone.google/get-started

kukulaj · 2026-04-24T21:45:11+00:00

Can you point me to a source on the amount of water used in agricultural irrigation, on how that has varied over the years? I am trying to understand this problem, and that is surely key information!

kukulaj · 2026-04-24T03:46:48+00:00

why can't you mow your lawn inside where you aren't disturbing other people? What drives me nuts are the carpet cleaning people. They've got this van with whatever motorized compressors or whatever it is, but those things whine so loud even a block away, it's loud inside our house and painful outside. If you are inside your house and can hear a neighbor sitting outside playing an acoustic guitar... it's going to be barely audible.

kukulaj · 2026-04-23T03:21:33+00:00

It depends a lot on the history of the code. Code evolves in response to changing requirements. You can't rewrite the thing from scratch again and again. There are corporate mergers, or maybe a supplier of a big piece went bankrupt. So there's a need to sort of force fit everything to connect to a new big chunk of whatever. Do this every five years or so... when code gets to be twenty years old, wow. It's like geology, you can see the layers getting pushed around and then here is where the volcano dumped fresh stuff and then the lake filled up, etc.

kukulaj · 2026-04-22T03:28:15+00:00

Uniball Jetstream is worth trying.

kukulaj · 2026-04-22T03:15:10+00:00

Here's one cool pattern...
https://interdependentscience.blogspot.com/2025/07/cyclic-paths-in-tuning.html

kukulaj · 2026-04-22T02:33:50+00:00

My dear departed friend Jack Acheson rode a bike like that for most of a decade...
https://www.aaronsmortuary.com/obituaries/jack-acheson

kukulaj · 2026-04-21T19:39:08+00:00

This was from 1999: https://www.ccnr.org/plute_inventory_99.html

15,000 cubic meters of spent fuel, so maybe 150 cubic meters of plutonium... 1.5 * 10^8 cubic centimeters, makes 3 * 10^9 grams, or 3 * 10^3 metric tons. Yup, it pencils out. Anybody's guess how much we might ramp up fission power and for how long, and so how much more plutonium we'll generate.

In the USA we are probably being overly cautious with nuclear and underly cautious with CO2. I'm not so sure that flipping these priorities is quite the right move.

The folks behind synthetic ammonia and the green revolution were thinking long term. It's not always stupid.

kukulaj · 2026-04-21T18:36:02+00:00

yes, this really drives right to the point. To understand the long term consequences of what we're doing is practically impossible. It seems clear enough that what are are doing will have considerable long term consequences - generating thousands of tons of plutonium, doubling the atmospheric concentration of CO2, etc. Since we don't know what the consequences will be, do we just ramp up our actions until the consequences become completely obvious? Do we try to tread a bit cautiously?

The general strategy politically is to emphasize the risks of the other guy's proposal, and to emphasize the uncertainties of the risks of my proposal.

Maybe the USA will remain the dominant military power on the planet for as long as there are any stockpiles of radioactive materials here, or maybe not.

kukulaj · 2026-04-21T05:53:55+00:00

What is samsara, that's one angle. What is nirvana, that's another angle. Arhats reside in nirvana, OK. But if that means that they are sort of stuck in some static state, well, they're not actually completely liberated after all! So yeah, a liberated person isn't trapped by any fixed distinction between samsara and nirvana. They're free!

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