Re: Ontology and Physics
I came across this by G. J. Chaitin the other day. The "2 March 2000 Carnegie
Mellon University School of Computer Science Distinguished Lecture":
http://www.cs.auckland.ac.nz/CDMTCS/chaitin/cmu.html
It's a fun read.
Most recently he has published this (in the March 2006 issue of
Scientific American, I believe):
http://www.cs.virginia.edu/~robins/The_Limits_of_Reason_Chaitin_2006.pdf
-Rob
On Monday 19 June 2006 07:06, John F. Sowa wrote:
> I recently had some offline discussion about some issues
> in physics, which is the most basic of all the sciences
> and the one in which the theories have been developed
> with the highest degree of precision.
>
> Yet engineers who have a practical problem to solve never
> use anything that remotely resembles a unified theory of
> everything in physics. There are some very, very good
> approximations, but all of those approximations are highly
> context dependent. Each of them is based on a different
> set of simplifying assumptions, and nobody ever goes back
> to some fundamental theory, such as general relativity or
> quantum field theory, in designing an airplane or predicting
> the weather.
>
> Even for a subfield, such as electromagnetism, for which
> Maxwell's equations were formulated in the mid 19th century,
> an enormous number of practical problems are still solved
> by trial and error. A famous example is antenna design
> for radio, TV, radar, etc. Practitioners in the field
> say that it's more art than science, and when they find
> something that works, they copy it without completely
> understanding how and why it works.
>
> Given this mess of unrelated and mutually inconsistent
> "microtheories" in physics, which is the most precise of
> the hard sciences, I am amazed that people think it might
> be possible to have a unified set of general axioms that
> would cover all or even some significant number of business
> applications on which computer systems must interoperate.
>
> I'm not saying that it's impossible. I'm just asking people
> to look at history. Following are two notes I sent recently.
> The first is in answer to a couple of questions, and the
> second is a recommendation for a book on physics.
>
> John Sowa
>
> -------- Original Message --------
>
> To start with the last question,
>
> > And from where is it known that the effect of a force
> > is proportional to the 2nd derivative of the position,
> > rather than (e.g.) the third derivative? Pure reasoning?
> > Or empirical observation generalized?
>
> There's an enormous amount of guesswork in the search for
> fundamental principles. And it is very hard to distinguish
> the principles from the concepts they relate. For example,
> consider Newton's basic F=ma. The only thing that is
> independently measurable is the acceleration. The force
> and the mass cannot be measured independently.
>
> There is also the fundamental question about the difference
> between the mass as measured by weight (i.e., gravity) and
> the mass as measured by inertia (i.e., F=ma). Newton assumed
> they were the same, but that is a pure leap of faith, which
> for reasons that were mysterious to many people (including
> Einstein) turned out to be justified by measurements.
>
> Newton based his work on Galileo and Kepler, among others,
> but both of them had a lot of guesswork intermixed with
> metaphysical discussions. And Kepler used the results of
> his mentor, Tycho Brahe, who did the most careful possible
> measurements in the hope of proving that Ptolemy was right
> and Copernicus was wrong.
>
> For essentially every concept in physics, there has been
> many years of guessing, debate, observation, mathematical
> formulations, and more iterating back to the guessing stage.
>
> > Do you know where the laws of conservation of momentum &
> > energy come from? Mr. Newton, perhaps?
>
> Leibniz and Newton were debating which, if either, was conserved
> -- and what to call those mysterious properties that were or
> were not conserved. Descartes and Newton believed that the
> product mv (what we now call momentum) was conserved, and
> Leibniz argued that mv**2 (what we now call kinetic energy)
> was conserved. The notion of potential energy and the idea
> that mechanical energy could be converted to heat energy and
> back was not sorted out until the middle of the 19th century.
>
> There are two very good volumes about the historical development
> of the concepts of electromagnetism, heat, and light, which go
> into all the debates about what those mysterious things could
> possibly be and the very many different hypotheses that were
> proposed, debated, measured, and revised, for centuries:
>
> _A History of the Theories of Aether & Electricity_ by
> Sir Edmund Whittaker. Vol. 1, the Classical Theories to 1900,
> Vol. 2, the Modern Theories to 1926. Third vol. never finished.
>
> I bought the paperback versions in 1960 ($1.95 for vol. 1 and
> $1.85 for vol. 2). They were reprinted by Dover in 1990, but are
> now out of print. Second-hand prices range from $120 to $400.
>
> The short answer is that it's very hard to sort out what is
> mathematics, what is physics, what is metaphysics, and what is
> wishful thinking. The amount of confusion over the centuries
> has been enormous. But that seems to be par for the course.
> _________________________________________________________________
>
> I realize that you already have an ambitious reading list,
> but I thought that I'd add one more thing to consider:
>
> _The Road to Reality: A Complete Guide to the Laws
> of the Universe_ by Roger Penrose, Knopf, New York.
>
> This is an 1100-page tome that covers all of modern
> physics without skimping on the math. However, it's
> beautifully written, and the first 3 or 4 pages of
> each of the 34 chapters give a good intuitive overview
> of the topic of that chapter.
>
> It is possible to skip around and just start reading
> at the beginning of any chapter, even the concluding
> Chapter 34, which predicts that there will be a major
> revolution sometime during the 21st century that will
> create as many or more upheavals as the revolutions
> of relativity and quantum mechanics at the beginning
> of the 20th.
>
> It's the book I would have loved to have on my shelf
> when I was an undergraduate studying math and physics.
> For example, Chapter 6 is an 18-page summary of calculus,
> which is an excellent review for people who forgot
> everything they had learned and a lovely summary for
> people who still remember it.
>
> Chapter 16 is a good 25-page summary of Cantor's
> set theory, the hierarchy of infinities, Turing
> machines, and Goedel's theorem with good intuitive
> discussion of what they mean.
>
> Following are two reviews. The first is by
> Martin Gardner:
>
> http://www.newcriterion.com/archive/23/oct04/gardner.htm
> Theory of everything by Martin Gardner
>
> And following is the review from _The American Scientist_:
>
> http://www.americanscientist.org/template/BookReviewTypeDetail/assetid/4591
>9;jsessionid=baa6VA3Vgqo985