LLMs Predict My Coffee

(dynomight.net)

36 points | by surprisetalk 4 days ago ago

11 comments

  • amha an hour ago

    There's a simple differential equation often taught in intro calc courses, "Newton's Law of Cooling/Heating," which basically says that the rate of heat loss is proportional to the difference in temperature between a substance and its environment. I'm curious what that'd look like here. It's a very simple model, of course, not taking into account all the variables that Dynomight points out, but if a simple model can be nearly as predictive as more complex models...

    I'm also curious to see the details of the models that Dynomight's LLMs produced!

    • 3eb7988a1663 an hour ago

      The appendix lists the equations transcribed from the raw answers.

        LLM  T(t)  Cost
        Kimi K2.5 (reasoning)  20 + 52.9 exp(-t/3600)+ 27.1 exp(-t/80)  $0.01
        Gemini 3.1 Pro  20 + 53 exp(-t/2500) + 27 exp(-t/149.25)  $0.09
        GPT 5.4  20 + 54.6 exp(-t/2920) + 25.4 exp(-t/68.1)  $0.11
        Claude 4.6 Opus (reasoning)  20 + 55 exp(-t/1700) + 25 exp(-t/43)  $0.61 (eeek)
        Qwen3-235B  20 + 53.17 exp(-t/1414.43)  $0.009
        GLM-4.7 (reasoning)  20 + 53.2 exp(-t/2500)  $0.03
      • kurthr an hour ago

        It looks like a lot of them are missing something big. I'd think the two big ones are the evaporative cooling as you pour into the cup, and heating up the cup (by convection) itself. The convective cooling to the air is tertiary, but important (and conduction of the mug to the table probably isn't completely negligible). If there's only one exponential, they're definitely doing something wrong.

        I'd like to see a sensitivity study to see how much those terms would need to be changed to match within a few %. Exponentials are really tweaky!

    • amelius an hour ago

      That model doesn't explain the relatively sharp drop in the beginning.

      • bryan0 31 minutes ago

        Are you sure? I believe Newtown's law of cooling says the temperature will drop sharply at the beginning:

        dT/dt = -k(T_0 - T_room)

        so T(t) = T_room + (T_0 - T_room) exp(-kt)

        exp(-x) has a fast drop off then levels off.

      • coder68 38 minutes ago

        It does? There is a fast drop followed by a long decay, exponential in fact. The cooling rate is proportional to the temperature difference, so the drop is sharpest at the very beginning when the object is hottest.

        • amelius 33 minutes ago

          I mean that initial drop doesn't look like it is part of the same exponential decay.

  • andy99 an hour ago

      Does that seem hard? I think it’s hard. The relevant physical phenomena include at least..,
    
    In most engineering problems, the starting point is recognizing that usually one or two key things will dominate and the rest won’t matter.
  • IncreasePosts 3 minutes ago

    The water temperature drops quickly because the room temperature ceramic mug is getting heated to near equilibrium with the water. If you used a vacuum sealed mug(thermos) then the water temp would drop a bit but not much at all initially.

  • kaelandt an hour ago

    It isn't that surprising that it works well, this problem is fairly well known and some simple heat equations would lead to the result, about which there is a lot of training data online.

  • leecommamichael 27 minutes ago

    ... and so another benchmark is born.