by JLS
for the GC
"J", in comment on "Process and Conversation:
"the "stone-age" physics or if you will Aristotelian-Newtonian physics remains, at least in regard to OUR perception (and our language)."
That is interesting. I was surprised by the little space is given to "neo-Newtonian" stuff in the wiki entry for cosmology. I suppose it's just as well, but none of the discussion that would please a student of stone-age physics!
----
From the wiki entry on "alternate cosmologies" at
http://en.wikipedia.org/wiki/Non-standard_cosmology
Newtonian cosmology. Main article: Friedmann-Lemaître-Robertson-Walker metric#Newtonian approximation.
"While not seriously advocated by anyone after Einstein's development of relativity, Newtonian gravity can be used to model the universe and non-rigorously derive the Friedmann equations that are used in the big bang universe. This non-standard cosmology is mostly used as an elementary exercise for astronomy and physics students and doesn't represent a serious alternative proposal."
---- I should have a look at the main article they refer to, for tasters, as they say!
---- the use of "neo-Newton" rather than "neo-Newtonian" is Gricean, as when he speaks of contemporary authors as being a "neo-Thrasymachus" and so.
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This is not an accurate statement of the degree of support for Newton versus Einstein.
ReplyDeleteIts true that mainstream academia is pretty much dominated by relativists, but there is a very substantial fringe of dissenters among whom I believe the most popular dissenting theory is called "Newton's emission theory of light".
Mainstream academics will typically dismiss these dissenters as cranks, but there can nevertheless be no doubt that many of them are "serious".
The emission theory of light relates to the special theory of relativity, but this is the thin end of the wedge, the rejection of the general theory follows as night follows day.
Even among relativists there is a respectable group at Cambridge who do relativity in euclidean space time rather than incorporating gravity into the curvature of space, but beyond that it appears that the general relativity uses the curvature of space as a way of obscuring the fact that the general theory violates the special theory by allowing that gravitational influence propagates without delay (i.e. much faster than the speed of light).
Experimental evidence (I am lead to believe) suggests that the transmission of gravitational influence is not instantaneous but is much faster than the speed of light.
I am no expert myself, but I have to say that from
my (limited) reading of the evidence and arguments I am more inclined to doubt than to believe both theories of relativity, and consider that the alternatives should be treated more seriously than they are by mainstream academia.
In particular the principle evidence which is held by them to refute the Newton emission theory of light seems to me a joke.
RBJ
RBJ
Thanks, Roger. For the record: the wiki section on "Newtonian cosmology" has three links then: one is to the main article, which I have not yet consulted; the other is for the
ReplyDeleteFriedman equations, which I haven't either, and the third is for "Newtonian gravity", which I have! (seemed like the easier!). It is a long article, but the final section is Einstein on Newton, and indeed restates the excellent point made by Jones -- or something! --
"These objections were mooted by Einstein's theory of general relativity, in which gravitation is an attribute of curved spacetime instead of being due to a force propagated between bodies."
"In Einstein's theory, masses distort spacetime in their vicinity, and other particles move in trajectories determined by the geometry of spacetime."
"This allowed a description of the motions of light and mass that was consistent with all available observations."
"In general relativity, the gravitational force is a fictitious force due to the curvature of spacetime, because the gravitational acceleration of a body in free fall is due to its world line being a geodesic of spacetime."
The Friedman equation link can be overlooked, because the main article referred to is for the Newtonian approximation to the metric, and it's not so long, so I paste it. It reads that:
ReplyDelete"In a certain limit, the above equations
can be approximated by classical mechanics."
Must say I like that use of 'classical', as when Grice, I think, speaks of Principia Mathematica as 'classical logic' (although he refers to it as modernism, too).
"Early in history of the universe
when a is small enough, the spatial curvature of the universe, ka − 2, is negligible compared to the density term (proportional to a − 3 for pressure-free matter (also called "dust" or "cold matter") or a − 4 for radiation)."
"The cosmological constant term is also relatively small."
"Then one may neglect the terms involving k and Λ in the equations above, i.e. treat the universe as approximately spatially flat."
"As discussed above, by using the first law of thermodynamics, the pair of equations of motion can be reduced to a single equation."
"Let us then observe the first equation above, in the limit where both k and Λ are negligible."
"It can then be brought to the following form"
1/2a2 @ a28 piGρ
"This can be interpreted naively
as an energy conservation equation: the universe has a mass M proportional
to a3ρ, and thus its potential energy is proportional to
-GM2/a2 @ - GM ra2.
"Its kinetic energy, on the other hand, is proportional to .
1/2ma2
"Conservation of energy is thus
1/2ma2 - cMa2 Gr = 0,
with c some constant (not to be confused with the speed of light, also denoted by c in the previous sections)."
"Note that too early in the universe, this approximation cannot be trusted."
"For example, during cosmic inflation a cosmological constant-like term dominates the equations of motion."
"Even earlier, during the Planck epoch, one cannot neglect quantum effects."
I suppose I might add that this is one among many areas of science in which it is customary to speak as if the theory most fashionably in the higher echelons of academia were established fact.
ReplyDeleteThis is actually part of the social process whereby theories come to be "established fact", you talk as if they were, and eventually people are afraid of being thought lunatics if they express doubt.
We can see this also, for example, in Dawkins, who comes very close to dismissing group selection advocates as cranks, but perhaps can't quite get there because there is mainstream support.
I think a good rule of thumb is that if top scientists think it necessary to dismiss something out of hand (as having been definitively refuted, or without scientific basis), then there is probably something in it.
RBJ
My point was not quite as grandiose as the speculations JL has appended here. Classical mechanics still applies--say in regard to trajectories,momentum, and bodies in motion--aircraft descending. Or shuttles. Or AMTRAK. Special relativity would apply when those bodies approach the speed of light (ie, not to likely on a macro-level for some time, regardless of many frat-boys' Star Dreck fetish).
ReplyDeleteThe General theory applies to gravitation, does it not --a theory of gravitation. But in terms of applicability (and functionalism of some sort, per CS Peirce), Newtonian mechanics and the calculus--and really Euclidian space (even if...expanded with integrals)--while having certain limits (in regard to thermodynamics, and electronics) has not been overturned, however unhip that might seem.
But my meta-point (perhaps a bit quotidian for the GC) concerned the marketing of relativity and QM. Academia tends to portray classical mechanics as overturned, useless, or irrelevant, or something, and Guru Einstein as victorious, when there are still questions remaining (specifically in regard to the gen. theory).
Good points, Roger and J.
ReplyDelete---- I thought, when J was referring to the quotidian, J was going to talk about "ordinary language" -- my forte! ha ha! Philosophers of Grice's generation would speak of "ordinary language", rather than "English" because they did not want to sound too parochial! So, it may do to analyse to what extend "ordinary language", i.e. English, supports an Euclidean geometry cum Newtonian physics. Russell thought that ordinary language embodied a 'stone age metaphysic', which Grice rephrased as a 'stone age physic', at most. And many popularisers of twentieth-century physics (I am retro here and just refer to this, since Grice died in 1988) do speak of English as quite a neolithic thing, with some pretty restricted notions of 'distance' and such.
I suppose one way to go here is to consider interpretations of first order predicate calculus and how physicists of different 'schools' would go on to interpret it to fit their proposed theories. Only THEN we can start considering 'confirmation,' or disconfirmation' by evidence, it would seem.
Jones's reflection amused me and reminded me of what Myro called (in his contribution to PGRICE) the "Grice Rule" -- they would give seminars together, and Myro built up a "Grice Rule": If what Grice says strikes you at once at right, then it's wrong; and vice versa. He adds words to the effect that he won't disclose whether anything Grice ever said struck him as 'at once right'.