Re: Why is push gravity concept considered not viable by mainstream science?
- From: carlip-nospam@xxxxxxxxxxxxxxxxxxx
- Date: Thu, 25 May 2006 20:00:38 +0000 (UTC)
Blaze Labs <saviour@xxxxxxxxxxxxx> wrote:
Hello guys,
I would like to know the main reasons why the push gravity concept is
not considered as a viable concept by mainstream science.
There are a few generic objections, along with particular problems with
particular models. The main generic objections I know of are
1. Drag: As Feynman pointed out in the Feynman Lectures, anything
that's capable of "pushing" will also create drag on a moving object.
There are very strong observational limits on such drag, in the
Solar System and in binary pulsar systems.
2. Aberration: Suppose "pushing" particles move at a speed v, and
look at the effect on the Solar System. For a planet at distance d
from the Sun, the "push" will not be toward the instantaneous
position of the Sun, but towards its position at a time d/v in the
past. This is a drastic effect -- if v is the speed of light, the
Solar System would be drastically unstable over a thousand-year
time scale.
(The effect of aberration is to increase the velocity of a planet,
and you might hope that drag would cancel it. But it's easy to
check that such cancellation can occur at, at most, one radial
distance from the Sun.)
3. Principle of equivalence: It is observed that gravity acts not
only on mass, but on all forms of energy. A "push gravity" theory
would have to come with an explanation of how the particles that do
the pushing manage to push against, for example, electrostatic binding
energy and the kinetic energy of electrons in an atom, and why that
"push" exactly matches the "push" against ordinary matter.
In particular, we observe that gravitational binding energy itself
gravitates. This seems to require self-interaction among the
pushing particles. On the other hand, the accuracy of the inverse
square law over long distances requires that the self-interaction
be very small -- you certainly need a mean free path larger than
the size of the Solar System if you don't want to mess up Pluto's
orbit.
4. Gravitational screening: There are very strong limits on the kind
of "gravitational screening" one would expect from a "push gravity"
model -- see, for example, Unnikrishnan et al., Phys. Rev. D 63 (2001)
062002.
[...]
Please note, I am NOT asking about Le Sage ultramundane particles
theory (which also falls under the push gravity category), which I can
easiely discredit myself. I'm mostly interested in the concept of
electromagnetic radiation pressure of high frequency radiation acting
as the gravitational mechanism, and its shadowing creating the inverse
square law, low pressure areas.
You immediately run into trouble with the principle of equivalence,
for one thing. Electromagnetic waves don't interact with other
electromagnetic waves (except by truly tiny quantum effects); but
gravity bends light. Nor do electromagnetic waves interact with
internal energy, not with neutrinos; but these *are* affected by
gravity. You also run into grave problems with aberration (see above),
and very probably with drag. You would *further* have to explain why
this high frequency radiation is not absorbed by the Earth enough to
lead to gravitational screening of the type ruled out by experiment.
Note that "high frequency [electromagnetic] radiation" is gamma radiation.
There are experimental measurements of very high energy gamma rays, and
a fair amount is known about their spectrum. I suspect you would have
a very hard time reconciling your model with these observations.
Steve Carlip
.
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