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ahbwramc comments on In praise of gullibility? - Less Wrong Discussion

23 Post author: ahbwramc 18 June 2015 04:52AM

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Comment author: Vaniver 18 June 2015 04:29:38PM 0 points [-]

I don't believe that in reality the precision of floats is a meaningful limit on the accuracy of climate forecasts.

How much experience do you have with scientific computation?

I would probably say that people who think so drastically underestimate the amount of uncertainty they have in their simulation.

Disagreed. The more uncertainty you incorporate into your model (i.e., tracking distributions over temperatures in cells instead of tracking point estimates of temperatures in cells), the more arithmetic you need to do, and thus the sooner calculation noise raises its ugly head.

Comment author: btrettel 20 June 2015 02:56:40AM *  1 point [-]

(i.e., tracking distributions over temperatures in cells instead of tracking point estimates of temperatures in cells)

Many combustion modeling approaches do precisely this. Look into prescribed PDF methods, for example. You can see the necessity of this by recognizing that ignition can occur if the temperature anywhere in a cell is above the ignition temperature.

(There is also the slightly confusing issue that these distributions are not the same thing as the distribution of possible realizations.)

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