Re: Questions (Space)

In article <1i4kach.72txwk1kyy51cN%spam@xxxxxxxxxxxxxxxxxxxx>,
spam@xxxxxxxxxxxxxxxxxxxx says...
Gerry Quinn <gerryq@xxxxxxxxx> wrote:

In article <slrnfeq9he.54t.antti-juhani@xxxxxxxxxxxxxxxxxxxxxxxxx>,
antti-juhani@xxxxxxxxxxxx says...

Only it turns out that, according to Einstein's general relativity,
Euclid's geometry is *not* the true geometry, it just looks like it.
It's good enough for ordinary life, but not good enough for discussing the
universe.

As I said elsewhere, there's no observational evidence that forces us
to interpret gravity geometrically. (Richard Feynman said it too, in
case anyone finds that more convincing...)

OTOH, it's currently the best theory we have (as in, can be used to
calculate real world things, as in GPS systems, planetary orbits etc.)

But you can use the very same math without assuming that the geometric
interpretation represents reality.

General relativity treats gravity as something other than a force. If
however you choose to assume gravity is a force, you get a
mathematically equivalent model in which spacetime is flat.

Whether gravity is a force that affects all mass/energy equally, or
whether gravity is something other than a force, is not something that
can currently be determined observationally in any obvious way. If you
are inclined to believe that quantum theory and thermodynamics are the
best guide to what the universe is really like, you may reasonably be
inclined to treat gravity as a force.

- Gerry Quinn


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Relevant Pages

  • Galathea conversation on emergent gravity
    ... "but just because many could understand does not mean many do understand because there are many other interesting things in this world there are many approaches to quantum gravity that explore higgs-like mechanisms" ... "the higgs mechanism has always been intimate ... and I have done so in an elementary way showing the connection/formal analogy to emergence in superfluid helium & in BCS superconductors. ... can always be interpreted as a lorentzian geometry ...
    (sci.math)
  • Re: Jack Sarfatti bio
    ... spin coefficients -- but not the tetrad. ... the higgs mechanism has always been intimate ... and it has been a regular source of quantum gravity speculation ... can always be interpreted as a lorentzian geometry ...
    (sci.math)
  • Re: New version of a relativity FAQ
    ... "Gravity" is a physical phenomenon, while GR is a THEORY of how gravity behaves. ... abandoning geometry because seriously flawed. ... that spacetime is curved and gravity geometrical because light bending can be explained with the same precision using a non-geometrical theory of gravity. ... You MUST be more precise in distinguishing theories from phenomena, and one theory from another -- your usage of "spacetime" twice in this sentence uses the same word to refer to two VERY DIFFERENT entities. ...
    (sci.physics.relativity)
  • Re: the basis of relativity
    ... With regard to the theory of gravity as I described it. ... Take some solution to Einstein's equations, then perturb the geometry ... I see the space-time dimensions as simply the dimensions of a normal ... a firm foot in measureable reality. ...
    (sci.physics.relativity)
  • Re: the basis of relativity
    ... > With regard to the theory of gravity as I described it. ... > one should say gravity is indistinguishable from geometry. ... spacetime being an imaginary frame for solving physics problems, ...
    (sci.physics.relativity)