On Sun, Aug 24, 2014 at 12:43 PM, David Roberson <[email protected]> wrote:
Eric, I suppose the difference between your beliefs and mine amounts to my > expectation that the climate change scientists should be held to a high > standard as is required of most other endeavors. You apparently are > willing to give them a free pass since you have a gut feeling that they are > right to some degree. > I don't think anyone is arguing for giving climate scientists a free pass for anything they want to do, anymore than we would argue here for giving physicists a free pass to endlessly pour money into ITER or the National Ignition Facility; certainly not me. I'm arguing for humility before expertise gradually developed in understanding a wicked problem. We can question policy and funding decisions that are based on uncertain conclusions. But stepping in and saying that we (the general public) are in as good a position to weigh the data as capable climate scientists is to lose a sense of the proportion in the face of the amount of time and effort that must be expended to discern signal from noise in a complex domain. Without such humility, we are prone to a little bit of unintentional hubris. It is similar to making the following statements as members of the general public: - What you electrical engineers are saying about instantaneous power is bunk. I know that if the sine and the cosine fluctuate too rapidly, they'll jam together like the keys on a typewriter and throw the power out of hoc. - Making a practical quantum computer is not as hard as you guys make it out to be, for I have built one out of an erector set and rubber bands and know something about the basic principles involved. - Moore's law is not at all insurmountable. The electrical engineers are simply failing to see that if you add in some refrigeration lines, the temperature will be sufficiently decreased to allow a continued exponential increase in circuit density. This is simple thermodynamics. This is probably what we sound like to people who have studied climate science when we interject with our analyses without having spent years of our lives trying to understand the nuances of the problem. One hesitates to do something similar in the context of LENR, and only does so because almost no one who has the proper qualifications is willing to undergo the stigma that will attach to anyone in physics who publicly examines LENR. The overfitting of a model to a set of data is a generally known risk, and ways of avoiding it are taught in undergraduate courses. If we do not give climate scientists the benefit of the doubt on this one, we will be proceeding from an assumption that they're incompetent. In trying to understand what climate scientists are doing, I would draw an analogy to using our knowledge of radioactive decay half-lives to understand how much of a radionuclide will exist after a certain amount of time. Because the process is a stochastic one, the knowledge of the half-life is close to useless in predicting whether an individual nucleus will decay at a certain time. But over a period of time, the half-life will allow one to calculate the amount of the original radionuclide remaining to within a high degree of precision. I doubt that this ability was something that was acquired overnight. It probably took a few years of trial and error to empirically tease out the exponential decay relation. But even when they were working with less than reliable models, I'm guessing they were able to discern the general trend. Another analogy to what climate scientists are trying to do is to that of a mechanical engineer attempting to predict the temperature of an engine that has been running for a certain period of time. It is probably difficult to predict the temperature at a specific thermocouple at an instance in time beyond a certain broad range. But I'm guessing that it's not too hard to anticipate the average temperature across the thermocouples after one has become familiar with the operating characteristics of the engine in question. Climate scientists are doing something similar, but at a stage when the laws of thermodynamics were less well understood. Nonetheless general trends can be discerned. I would not at all be surprised if the relevant time ranges for useful predictions in climate change models were on the order of decades. Each system being modeled has its own range of times within which statements are relevant. In some nuclear decays, the time range for some decays is on the order of 10^-8 - 10^-20 seconds. I would be surprised, in fact, if climate scientists were able to bring model predictions to within less than tens of years, given the great amount of latency involved for changes to show up in the system. As for climate scientists adjusting their models periodically in the face of new facts, I am reminded of a quote attributed to Keynes, who was responding to a similar complaint: "When my information changes, I alter my conclusions. What do you do, sir?" Eric
