JCNS,
You wrote, "If you've read any of my other posts in this or other FQXi blogs you must know that my approach to physics is naive, primitive, and visceral, but I hope not unscientific, in the best sense of that word."
Sure.
"I exist in a universe which, statistically, is mostly not hospitable to fragile life forms such as myself. Understanding physics, therefore, is, for me, a matter of survival as well as a matter of great intellectual curiosity and fascination."
I agree. I touched on this in my 2010 FQXi essay. "When one calculates
outcomes from a field of infinite parameters, the great majority lead an organism to extinction. Yet conscious creatures play with loaded dice; 'good' and 'bad' choices, assuming that all strategies are rational, i.e., survival-based, depend on having at least one good choice independent of all environmental influences considered as a continuum. E.g., if a one-celled creature needs light to survive, it either has the motive ability to seek
a light source in order to 'be,' or it ceases to be when the light goes away."
We're fragile only when we don't have options. More consciousness creates more survival options and more robust life. We're all complex systems of cooperating cells.
"The universe in which I find myself is extremely dynamical. There are lots of things in motion, cars, clouds, airplanes, planets, galaxies, occasionally (and frighteningly, during earthquakes and tornados) even pieces of buildings, trees, etc. If some of these objects were to collide with me it could be fatal at worst and uncomfortable at best. Again, understanding how this all works (i.e., understanding the laws of physics which appear to govern it all) on a visceral, intuitive level is essential to survival."
Absolutely.
"Tom, you wrote 'Point is, to get to these models where Lawrence among others can speak of group theory and noncommutative algebra to model physical phenomena, we have to go through what we know about the classical and quantum worlds and then follow the path where it leads without contradicting previous results. Intuition isn't much help.' My reply is that unless these models are taken to be purely academic, mathematical exercises they ultimately must tell us something of practical value about the universe in which we exist. It is this 'something' which I'm trying to tease out of our discussion. How will these models ultimately allow me to improve my chances of survival?"
Does electrical power improve your chances of survival? There's a story, maybe apocryphal but surely instructive, that a matron upon being introduced to Michael Faraday, asked of what use are his discoveries. Faraday supposedly replied, "Madame, of what use is a newborn baby?"
"Without a doubt, mathematical models play an important role in physics. At some point, however, mathematical models must somehow come into contact with empirical observations if they are to be of any real value, in my opinion. Granted, human experience and intuition are known to be extremely fallible, but that not withstanding they are still our only real basis for doing science (as opposed to pure mathematics)."
Actually, experience and intuition are of little use in doing science. Most of what we know, objectively, is counterintuitive. As Einsten said, "Imagination is more important than knowledge."
"Mathematicians presumably could develop a model of the Ptolemaic picture of the universe as readily as they could develop a model of the post-Copernican picture."
True.
"We then could talk about these two models in purely mathematical terms ad nauseam, but it is also satisfying to be able to talk also about the fact that one model has the sun revolving around the Earth whereas the other model has the Earth revolving around the sun while simultaneously rotating on its axis. One model ultimately is more useful than the other, despite the fact that human intuition accepted the less useful model as being "obviously" true for centuries."
They accepted it because of their quasi-religious philosophy that the circle represents perfection. A perfect universe, therefore, had to incorporate perfectly circular orbits (and they almost are, in fact). We should be wary of trying to impose religion or philosophy on science.
"As repeatedly noted elsewhere in these blogs, I'm a huge advocate of zeroing in on better and better paradigms. And I've long been concerned that the mainstream, prevailing paradigm for the fundamental nature of time is lacking. Not 'wrong' perhaps, but lacking, or incomplete. Inasmuch as 'time' plays such a central and crucial role in physics I believe it's worthwhile being certain that we have this paradigm nailed down as correct as possible."
How certain can we be of anything?
"Unless I'm mistaken (please correct me if I am), the prevailing paradigm for the nature of time may be summarized by the so-called 'operational' definition, i.e., 'time is that which is measured by clocks.' Clocks are then typically defined in some sort of slippery way as being devices which measure time by way of some sort of 'regular motion,' but it is never made perfectly clear how one would know whether motion was 'regular' or not without resorting to the use of a clock. I'm not saying that this is 'wrong' per se, but only that it seems, at best, incomplete. This view of time apparently leads logically to concepts such as block time."
Not regular motion -- regular physical processes. Motion is measured change in relative position among mass points. A physical process, however, need not involve classical motion. I won't get into a long discussion of the nature of time, about which I've written extensively. If you are interested, you can find my views here .
"In some of my essays such as 'Time: Illusion and Reality,' I've tried to suggest another paradigm, another way of looking at the nature of time, which, unfortunately, is also, in and of itself, incomplete I fear. In this way of looking at time our dynamical universe is the clock. Different physical configurations of the universe define, and are identically equivalent to, different particular times. This view does not allow for block time, and it makes a 'causal arrow of time' an inevitability. It further rules out time travel (at least of the variety portrayed in science fiction literature)."
Interesting. I'd say go for it, and build a mathematical model to accompany.
"Lawrence actually appeared to key in on this view in one of his posts to the article on 'Breaking the Universe's Speed Limit' when he wrote, "A[s] for block time being contrary to human experience or intution, those do not really count for much. The non-block time is just a system of spatial geometries which are related to each other by a diffeomorphism group. The notion of time is actually somewhat lost in this picture." Yes, in my view non-block time is indeed a system of spatial geometries! Exactly! But as he points out, the conventional notion of time is somewhat lost in this picture. And this may be where this paradigm is incomplete.
I can't help thinking that if some very clever person could somehow meld these two views of time the resulting paradigm might offer a more useful way of looking at the universe than any previously proposed. Unfortunately, I do not know how to accomplish this melding, but I sense that it would not be easy."
Easy or not, it's worthwhile. Google for Gerard 't Hooft's advice on how to be a theoretical physcist. Good list of prerequisites to study.
"Apologies for rattling on for so long."
Rattling makes music, too. :-)
Tom
