Re: Expansion and balloon analogy

TomGee wrote: 
But then it was noted that while galaxies are all moving away from each
other, their coordinates remain the same.  I.e., the distance between
them grows but they remain in the same spacial relationship as before.

Hmmm. "Coordinates remain the same" has no meaning at all independent of the definition of the coordinate system. "Spacial relationship" generally includes both direction and distance, so your claim here makes no sense.


Now that cannot be explained by balloons or raising breads. 

Those are _ANALOGIES_, not "explanations".


It seems
the only explanation possible is that the galaxies are not moving apart
from each other due to their own motions, but due to the expansion of
space!


"expansion of space" has no meaning.


So, to talk about the expansion of matter in regard to the expansion of
the universe is passe, to say the least.  It is not matter that is
expanding, but the distance between it.  We are not getting bigger at
all.  It is only space that is growing inbetween all discrete matter!
At least, that is the latest guess from the physics community.


Kinda-sorta.

In the FRW manifolds used for cosmological models, spacetime is permeated with a dense filling of dust particles. The elapsed proper time from the big bang for each dust particle defines 3-surfaces of simultaneity for the cosmologically-preferred time coordinate, and if one measures the distance between a given pair of dust particles on successive such surfaces, then this distance is increasing (for the portion of these manifolds corresponding to our current situation).


For something to do something in our universe requires energy of some
sort, but if space is empty, and unless we overthrow the Principle of
the conservation of energy and E=mc^2, it is not possible for space to
expand.

Not true in the FRW manifolds. No "energy" is needed for them to expand in the manner described above.

Attempting to do physics by sound bite is hopeless -- you need to actually STUDY the relevant theories of physics.


there must be a better
explanation than the counter-intuitive idea that space itself is
expanding.

There is. It's called GR and its application to cosmology via the FRW manifolds.


If space was expanding, why only between galaxies and not within them? 

See my previous posts in this thread.

>[...]


Tom Roberts	tjroberts@xxxxxxxxxx
.

Relevant Pages

  • Re: My remembrances of life during the war years 1939 - 1945
    ... Lovely story, Anita. ... Brings back long-forgotten memories. ... and the Home and Forces programme and Ack Ack Beer Beer, ... like you say Anita so many memories were uncovered writing these pieces ...
    (uk.people.silversurfers)
  • Re: Fifth postulate of Euclid and relativity
    ... >> Is that to account for timelike geodesics? ... > Lorentzian manifolds, specifically, not Pseudo-Riemannian. ... You should not expect to measure distance or time via a simple ...
    (sci.physics)
  • Re: Expansion and balloon analogy
    ... Remember that in cosmology, all we really can discuss are models.... ... time from the big bang for each dust particle defines 3-surfaces of simultaneity for the cosmologically-preferred time coordinate, and if one measures the distance between a given pair of dust particles on successive such surfaces, then this distance is increasing. ... In any case, in the FRW manifolds the constant-cosmological-time distance between a given pair of dust particles changes over cosmological time, and no energy is involved. ...
    (sci.physics.relativity)