[ExI] Dark energy = (anti)gravity?

[Stuart LaForge]

John Clark wrote:

> On Mon, Oct 2, 2017 at 3:21 AM, Stuart LaForge <avant at sollegro.com>
> wrote:
>> The entropy of a state with a probability of 1 is ln(1)
>> ? ?
>> or precisely zero ? ?
>> in both Boltzmann and Shannon formulations. I didn't know this was even ?
>> ?
>> controversial.
>
> ?Entropy is proportional to the logarithm of the number of ?
> ways previous micro-states ?could have produced the present macro-state,
> but if at the start of time the universe was in one state there were no
> previous micro-states ?, or previous anything.

Thermodynamics says that entropy is a function of state. That means it is
path independent so it doesn't matter how the universe got into its
initial state of zero entropy because all paths, including reversible
ones, are equally valid. When all possible paths lead back to the initial
state, it is the same as as having always been in that state.

>> if the universe has a single age that all observers can agree upon,
>>
>
> But they don't agree, some observers will say the universe is older than
>  others.

If that is the case, then of what use is the cosmological principle? Why
even bother talking about the universe as some distinct entity unto itself
that can have a definable age?

>
> There is no universal time everybody can agree on. ?If a traveling
> observer goes from point A to point B the Proper T
> ime ?of that ?
> ? journey is the time measured by the observers own stopwatch and using
> the traveling observer's definition of simultaneity to decide when to
> start and stop the stopwatch. But there is no universal agreement, some
> observers will say the stopwatch is running too slow, others will say it
> is too fast, and they will say the traveling observer started and stopped
> the watch at the wrong time.

But in the case of the universe, all those stop watches started at the
same time and in the same place. They would have gotten out of synch over
the years due to local space-time curvatures but you should be able to
average all those stop watches together and get something like a "true
age" of the universe.

>> So Noether's theorem and Einstein's equations could both be satisfied
>> given the correct boundary conditions.
>>
>
> ?Noether's theorem says that if the laws of physics tell a system to
> behave in a certain way at one time and the system behaves the same way at
> any other time then energy is conserved, but it won't behave the same way
> at a different time because spacetime is accelerating.?

Perhaps, but then the constants of nature ought to smoothly change over
space-time. They wouldn't change drastically all of a sudden. Thus they
are still of value as approximations that are asymptotic to an unknowable
truth.
BTW my equations also predict an accelerating universe.

>> the curvature of the universe as a whole has been bounded to be within
>> +/- 0.004 which causes the flatness problem. The FLRW metric
>> implies that if the universe has so little curvature now, in the
>> beginning it would have to have had way less curvature, on the order of
>> 10^?62. That
>> is so infintesimally small that the probability of such an arrangement
>> so close to zero, without actually being zero, is vanishingly small.

> ?I don't know how you could even assign a probability to something like
> that. If the universe is infinitely large and negatively curved you'd
> expect the local curvature to be ? vanishingly small ?. ?Even if the
> universe is finite the local curvature would still be unmeasurably small
> if the universe were big enough. But is the universe big enough? I can't
> even make a guess about that.

Well if the universe is negatively curved and infinite then the
philosophical implications are similar to a flat universe of infinite
extent.

The truth is we don't know and might never know. But a flat universe can
conserve energy and that is thermodynamically satisfying. In a flat
universe, dark energy is just superluminal gravity at long ranges. That is
epistemologically satisfying.

And the philosophical benefits of an infinite universe are also
satisfying. It would mean that we too are infinite with countless copies
repeated through time and space across the cosmos. Countless versions of
us living identical lives. Countless versions of us living every possible
permutation of our lives. Infinite copies of us taking every possible road
almost all of which are unique.

With all that infinity offers, I would say that Pascals wager might apply
to a flat universe. Or even a negatively curved one.

>> And in a flat universe, GR conserves total energy at least according to
>>  the Friedmann equations and my potential field equations.
>
>
> ?If ?
> spacetime ? is not evolving then energy is conserved, but we now know
> something Friedmann did not ; spacetime is evolving, not only is it
> expanding it's accelerating. ?
>
> ?From  Sean Carroll at:
> http://www.preposterousuniverse.com/blog/2010/02/22/energy-
> is-not-conserved/?

>From Carroll's blog post that you cite:

"And in my experience, saying “there’s energy in the gravitational field,
but it’s negative, so it exactly cancels the energy you think is being
gained in the matter fields” does not actually increase anyone’s
understanding — it just quiets them down. Whereas if you say “in general
relativity spacetime can give energy to matter, or absorb it from matter,
so that the total energy simply isn’t conserved,” they might be surprised
but I think most people do actually gain some understanding thereby."

Here Carroll makes it clear that he denies the conservation of energy to
avoid having to explain negative energy to people. It's a pedagological
choice he makes, not one based on mathematical reasoning. It is clear here
from his explanation here that curved space-time acts exactly like a
potential gradient and negative energy behaves like potential energy.

I don't see how Carrolls pedalogical choices affects the validity of my
theory.


>> as the density approaches an assymptote at located at twice thecritical
>> density
>
> Dc = 3H^2/(8*pi*G),
> ?The equation is correct but keep in mind ?
> H, the Hubble parameter
> ?,?
> is not a constant ?but is
> decreasing with time. And the value of Dc is not just determined by the
> mass of matter in a unit of space, pressure and tension are also part of
> it.

First off keep in mind that in a flat universe Dc is not just the critical
density of the universe but also the actual density of the universe.

And H is only decreasing with time only if the density of the universe is
likewise decreasing with time. But if the density of the universe is
increasing with time through conservation of energy and increasing
entropy, then H is getting bigger over time while our cosmological horizon
shrinks.


> No, communicating is not the same thing as influencing, communicating
> involves transferring Shannon style information and ? ?
> entanglement ? ?
> can't do that faster than light. But it will still let you influence
> things faster than light.

Good. That's all my theory needs is for gravity to be able to "influence
things" faster than light. No Shannon entropy need be exchanged.

>> My point is that you *can't* use it to send messages into the past.
>> Only
>> the universe can. It's like a private communications channel between
>> particles to exchange quantum information like position and momentum.
>>
>
> OK that might be true, it sounds rather like John Cramer's transactional
> interpretation of quantum mechanics; but I have to say backward causality
> makes me nervous even though ? ?
> nothing ? ?
> Shannon
> ? ?
> would recognize as information is sent into the past and so ?no ?
> paradoxes ? ?
> are ? ?
> produced.

It's certainly similar to Cramer's transactional interpretation in that
regard although mine is not quantitized. And Cramer's doesn't deal with
gravitation.

My earlier attempts at quantum gravity have been overturned by the
super-long Compton wavelength of the graviton reported by LIGO. It seems
unlikely at this point that the Planck constant applies to gravity waves
the same way it does to light.


>> I know it is unintuitive that gravity could be both an attractive and a
>> repulsive force based on density rather than something like charge.
>>
>
> Einstein says density isn't the only thing that makes a gravitational
> field, pressure and tension do too, and tension (negative pressure) makes
> gravity repulsive if the tension is strong enough. And ? ?
> Dark Energy isn't made of matter so it doesn't become less dense as space
> expands instead it is a property of space itself ?,?
> so the density of Dark Energy remains constant regardless of how much
> space expands. Because Dark energy is persistent it gives a constant push
> to the universe, and if you push on something with a constant force it
> will accelerate.

My equations simply lump pressure and tension together with matter density
and radiation density through the mass-energy equivalence principle. It
just deals with total density of all components of the stress-energy
tensor converted to mass.

>
>
>> ?> ?
>> BTW, as a testable prediction my theory predicts that objects inside an
>> ? ?
>> evacuated hollow spherical shell at zero G, should very slowly gravitate
>>  ? t?
>> o the closest part of the hollow sphere unless they were in the exact ? ?
>>  center. ? ?
>> This is in direct contradiction to what Newton's shell theorem predicts
>> by ? ?
>> purely attractive gravity.
>
>
> It seems to me that is pretty good evidence your theory must be wrong.
> ? ?
> A simple corollary to
> ? ?
> Newton's shell theory
> ? ?
> states that externally the sun's gravitational field behave ?s?
> as if all it's mass were concentrated at it's center point, if this were
> not true the orbits of the planets would be quite different from what we
> have observed and would have been noticed centuries ago.

Actually no because my theory predicts that external to the sphere, at
least locally, the hollow sphere still behaves gravitationally as a point
mass out to the radius of its zero-potential sphere.

Alas my suggested experiment is none-the-less untenable. No interferometer
is sensitive enough to detect such a small acceleration within any
reasonably sized sphere.

Stuart LaForge