Re: What if gravity isn't a force, just an illusion of expanding spacetime's momentum?


"cfk" <ckurasek@xxxxxxxxx> wrote in message
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On Jul 20, 9:21 pm, "Bill Hobba" <rubb...@xxxxxxxx> wrote:
"cfk" <ckura...@xxxxxxxxx> wrote in message

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Could it be possible that gravity isn't a force per se, rather
spacetime expands at a rate proportional to the mass occupying it and
the distance from the mass (like an expanding light cone, only made
from the spacetime 'fabric'), and the 'force' of gravity is really
just an illusion that's an artifact of the expansion (like centrifugal
force isn't really an independent force)?

How does the expansion generate the force? If everything expands what
presses against what?

Rest of misconceptions snipped.

Bill

If one accepts that spacetime is indeed a fabric that is expanding and
consequently affects matter and energy, then inflation would be
affecting everything, including us.

Sure - it is quite possible everything is getting bigger - including
ourselves. But if such was happening it would have zero experimentally
detectable effects because all our rulers etc would be affected as well so
everything would measure the same. It would generate no forces anymore than
you would expect forces to appear if you projected movie onto the wall next
to your bed or a cinemascope screen

If spacetime was expanding at
different rates (e.g. in proportion to the mass occupying it), then
the effects would not be uniform. We know that all galaxies are
moving away from us and at an accelerating rate proportional to it's
distance from us, so from our relativistic frame, inflation is not
having uniform effects.

So what if the rate of inflation of the spacetime occupied by the
earth was 9.8 m/s^2 at the crust,

A simple goggle search will return the correct semantics of what is meant by
universal expansion - because that is what the above shows - you are mixing
the meanings of words in atrocious ways that are laughable - eg
http://en.wikipedia.org/wiki/Metric_expansion_of_space
'The metric expansion of space is a key part of science's current
understanding of the universe, whereby spacetime itself is described by a
metric which changes over time in such a way that the spatial dimensions
appear to grow or stretch as the universe gets older. It explains how the
universe expands in the Big Bang model, a feature of our universe supported
by all cosmological experiments, astrophysics calculations, and measurements
to date. The expansion of space is conceptually different from other kinds
of expansions and explosions that are seen in nature. Our understanding of
the "fabric of the universe" (spacetime) requires that what we see normally
as "space", "time", and "distance" are not absolutes, but are determined by
a metric that can change. In the metric expansion of space, rather than
objects in a fixed "space" moving apart into "emptiness", it is the space
that contains the objects which is itself changing. It is as if without
objects themselves moving, space is somehow "growing" in between them.
Because it is the metric defining distance that is changing rather than
objects moving in space, this expansion (and the resultant movement apart of
objects) is not restricted by the speed of light upper bound that results
from special relativity. Theory and observations suggest that very early in
the history of the universe, there was an "inflationary" phase where this
metric changed very rapidly, and that the remaining time-dependence of this
metric is what we observe as the so-called Hubble expansion, the moving
apart of all gravitationally unbound objects in the universe. The expanding
universe is therefore a fundamental feature of the universe we inhabit-a
universe fundamentally different from the static universe Albert Einstein
first considered when he developed his gravitational theory.'

If the expansion varied it would happen over such a vast distance as to have
zero observational effects locally. Indeed bound objects like ourselves and
the earth are not subject to this expansion which really only applies to
cosmological sized objects like clusters of galaxies - if such was not the
case it would have been noticed long before now. Either that or the effect
is so small as to be negligible.

while the inflation of the spacetime
occupied by the average human was something negligible (e.g. 9.8 x
10^-10 m/s^2). Due to the greatly disparate rates and 'force' of the
planet's expansion, the earth's spacetime inflation would overwhelm
the average human's spacetime inflation, essentially becoming the
floor of the elevator that is uniformly accelerating into the feet of
the rider. Taking this assumption further would imply that by
remaining stationary for a long enough period of time, any object
would begin to levitate. This can be addressed by assuming the
disparity in the force of the two expansions (i.e. the human's vs. the
earth's), ends up folding over the lesser expansion. A similar
analogy would be tectonic plates - if a massive plate is moving at a
relatively high velocity and collides with a stationary plate that is
much thinner and less massive, the thinner plate will buckle, either
being forced underneath the heavier plate, or forced upwards (e.g.
creating a mountain range). So the implication would be the spacetime
inflating under the 'weaker' force would buckle / fold (potentially
into another dimension?).

The interactions between two bodies of similar mass would be
determined by the distance between the two centers of mass - the
further away from the center, the exponentially slower the expansion
propagates (just as the intensity of light from a light source). If
two equally massive bodies are close enough that the interaction
between the two rates of inflation maintains enough energy, then both
'plates' end up buckling / folding, with the 'fold' somehow pulling
the two bodies together, essentially bringing the bodies together at a
rate proportional to the decreasing distance between them.

And to explain the inflationary behavior of distance galaxies, one
could assume that if two regions of expanding spacetime interact at
distances sufficiently beyond the event horizon at which buckling /
folding would occur, those two 'fronts' of spacetime would meet and
simply push against each other, explaining why the universe can be
expanding at accelerating rates, without having to take a leap of
faith that there's some 'dark energy' out there counteracting the
traditional concept of gravity.

An overall analogy would be taking two pieces of cardboard coming out
of cardboard-making machines that are levitating with zero lateral
friction holding them in place. If both machines produce cardboard,
when the two fronts of cardboard meet, the machines will start moving
away from each other (giving us inflation that accounts for gravity
and does not require dark energy).

If the machines are making cardboard at an extremely high rate, the
meeting fronts of cardboard may either buckle or displace each other,
again behaving like tectonic plates, only somehow the folding /
buckling material ends up moving faster than the rate of either
independent rate of cardboard production, 'pulling' the two machines
together. (Obviously there needs to be an explanation for why once the
cardboard displaces from the horizontal plane it starts moving faster
than the rate at which it's respective machine is making it.)

If one machine is making paper (a human) and one is making cardboard
(earth), then when the cardboard and paper meet, the paper will not
provide much resistance, such that the cardboard will easily reach the
paper-making machine and start pushing on it (and nobody would claim
the cardboard was attracting the paper-making machine via any force).

I realize this is still not the most comprehensible explanation of the
idea, so let me know if this still doesn't make sense.

It makes zero sense.

It sounds to me like you have been influenced by crank writings like Mark
McCutcheon:
http://motls.blogspot.com/2005/08/common-crackpots-errors.html
'It is truly simple to rule out some of the silliest theories proposed by
crackpots. For example, Mark McCutcheon argues that there exists no
universal force of gravity and Newton's unification of the terrestrial
gravity with the celestial gravity was a misconception. However, the
apparent existence of NASA (something that most kids can see on TV) that is
able to calculate and control the trajectory of their shuttles - for whom
both terrestrial gravity as well as celestial gravity is important - should
be enough for a person with IQ above 55 (and above 4 years of age) to figure
out that something must be wrong with McCutcheon's theory. The crackpots
often ignore a majority of the phenomena that are clearly relevant for their
theories and they don't care.'

Bill


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