----- Original Message ----- From: "Erik Reuter" <[EMAIL PROTECTED]> To: "Killer Bs Discussion" <[EMAIL PROTECTED]> Sent: Tuesday, July 22, 2003 5:41 AM Subject: Re: Science and knowledge
> On Tue, Jul 22, 2003 at 12:08:43AM -0500, Dan Minette wrote: > > > It was the alternate thinkers who insisted that science must describe > > reality. > > Is Feynman an "alternate thinker"? He said that "the test of all > knowledge is experiment". That sounds to me like he thinks scientific > knowledge should be about experimental reality. > > > The answer to whether these particles really have infinite charges is > > "shut up and calculate". > > No, the answer is to hypothesize "they don't have infinite charge" and > then come up with an experiment that can verify or falsify the claim. Its not really that simple. Let me give an example of another part of QED. Feynman has a number of virtual particles in QED. These particles are virtual in that they spring in and out of existence in such a manner that the non-conservation of energy is within delta-t delta-E. There is another formulation of QED without the existence of these particles. On the whole, there would be a prejudice towards a model without such particles because postulating unseeable particles is considered a minus. But, IIRC, there are other difficulties with this formulation that keeps it from being the preferred one. The predictions of the two formulations are identical; they have to be because QED is very well verified. But, the descriptions of reality are quite different. The logical conclusion is that the existence or non-existence of virtual particles is moot. This brings up a feature of science that isn't always well represented in the textbooks. There are often several ways to skin the cat. Scientists usually have a hierarchy of things they are willing to do; or willing to throw away. One can usually fit data several different ways, and one can do it in a manner that further experiments will not distinguish between the ways. In that case, the hierarchy is used. One of the things that is low on the acceptability list is an artificial fudge factor. The problem with such a fudge factor is that it is fairly easy to use; and allows one to bypass more elegant solutions. Renormalization is a very good example of a fudge factor. If this type of fudge factor had been used elsewhere, it would have bypassed very elegant solutions. But, after over 20 years, the time had come to bite the bullet and just use a fudge factor. Fifty years from then, it appears that this was clearly the best choice. But, it is still recognized as a fudge factor. So, how is this handled? By deliberately tabling questions of reality. That is what "shut up and calculate" means. > If it cannot be falsified, then the answer is to suspend judgment. Is > it so hard for you to say "I don't know, so I will suspend judgment?" So, we suspend judgment on this type of question over and over and over again. A pattern emerges. We see that we continually suspend judgment on a certain type of question. The logical conclusion from the pattern is that our theories do not address the questions for which we suspend judgment. That is what I've done. > > But, the physicists who made progress didn't worry about the reality. > > Those that did, got little done. > > Baloney. Did Feynman get little done? No. He specifically sidestepped the question of reality. Indeed, if you look at the history of QED, one of the sources of his breakthrough was this sidestepping. The original QM folks worried about how the world could be the this way. He didn't. His model fit observation, end of story. The one great physicist of the 20th century who did not sidestep this question was Einstein. He was adamant about having a realistic understanding of QM. As a result, his productivity came to a screeching halt; and he produced little or nothing over the last half of his career. Now, I'll agree that physicists usually have their breakthroughs early. But his step function of productivity was remarkable. >He was certainly concerned whether his theories were experimentally verifiable. Yes, but his answer to whether things were real was "shut up and calculate." So, this definitely fits my understanding that the purpose of science is to describe and predict observations, period. > > > Finally, what happens when there are two models, with very different > > descriptions of reality, that both describe observations equally well. > > Are both real? Is neither real? > > That is a problem with your model based definition of science. So what are theories if not models; ontological statements? >Science is about testing knowledge by experiment. Knowledge of what? Think of the examples of two very different sounding descriptions that both fit the data equally well. Which one is simpler is a matter of taste. There are no experimental tests that can tell them apart. Which one is right? (BTW, if you look at the writings of another physicist on this list, Richard, you'll see that he has independantly stated that this situation is fairly common.) My answer is that they are both equally valid. Which one is used is a matter of taste, or convention, or even inertia. The differences between them are not part of science. Dan M. _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
