I don’t write often, but when I do it’s to procrastinate.

Hello, we haven’t spoken in a while. I hope you’re well. A lot has been happening. Dirigible is doing well. LLMs are exploding in popularity, and changing the world.

While experimenting with GPT2 (humblebrag, indie, I was here first, get off my lawn), I saw glimmers of brilliance. A computer can create a sentence. It wasn’t purely programmatic. It felt profoundly indeterministic. It seemed to have it’s own creativity.

Of course we know that’s not true. LLMs ‘merely guess the next word’. You can set a seed and settings and get the same response every time, now. However the illusion of creativity is almost as impressive as the reality of it.

Much of the response I got then was “wow that’s cool, who cares?”.

Now I use an LLM every single day. It’s in my code editor. I ask it questions like this:

“How much C02 can be left in a 5 lb tank before the pressure goes down enough to be noticeable?”

Jake A. Casey

Dumb Human

I asked this because my sodastream stopped working. I suspected it was a faulty gasket, but after tipping the thing upside down and dumping water all over my kitchen, it looked fine. After some old-fashioned googling, somebody on Reddit described solving their problem with a new tank, and I thought: “Well hold on a minute, I don’t actually have a way of knowing how much CO2 is left in that tank.”

It’s still spitting out air though, so it can’t be empty, right?

So I asked ChatGPT. Turns out there’s a label for the tare weight, the empty weight of the tank, near the top of most canisters. Sure enough, it read “T11lbs”. So we go and weigh the tank. The dusty digital scale in my bathroom blinks 11.4lbs at me (considerably less than what it usually blinks).

Well, doesn’t seem like much above empty, though I don’t know enough about gas physics to say for sure. Back to ChatGPT.

“In your scenario, if the tank originally contained 5 lbs of CO2 and now contains 0.4 lbs, it’s highly likely that all the liquid CO2 has been used up, and only gaseous CO2 remains. This means that the pressure in the tank will be significantly lower than the initial pressure when the tank was full.”


An actual robot

Ok, but remember, LLMs hallucinate. Hallucinate is a fun way of saying ‘saying something wrong, very confidently’. Which I do all the time. It’s great fun, you should try it. Anyway, we have to be careful of taking everything an LLM says at face value.

So how can I at least check to see? I’ll have it reason in the other direction. I have no idea if this is more sound or not, but it sounds like it to me.

In the first chat I reasoned forwards from the .4 lbs number: “Is .4lbs of co2 enough to maintain the initial pressure when a 5lb tank was full?”

In a second separate chat, I reasoned in the opposite direction to see if we’d get a similar answer: “how many lbs left in a 5lb CO2 tank before there is no more liquid co2 in the tank?”

“… Given these complexities, we can make a rough estimate. When the liquid CO2 is gone, the remaining gas in the tank might be a fraction of a pound, probably less than half a pound, but this is a very rough approximation. For precise measurements, one would need to know the exact conditions of the tank (pressure, temperature) and use the ideal gas law or real gas equations to calculate the mass of the gas remaining.”


I think the beauty of this is not that I’ve come to a conclusion of what I need to do, but that I learned things in the meantime. I’ve learned where to find the tare weight of a CO2 tank. I’ve learned that I can get a guess at the amount of CO2 left in the tank by weighing it on my bathroom scale. I’ve learned that the pressure can go down enough that even though the tank isn’t empty, it might be useless for carbonation.

I’ve also learned that even spending this much time on this problem makes me a giant nerd.

A nerd that needs a new CO2 tank. Thanks for reading.