[ExI] Dark Energy and Causal Cells
John Clark
johnkclark at gmail.com
Sun Feb 18 22:51:41 UTC 2018
On Sat, Feb 17, 2018 Stuart LaForge <avant at sollegro.com> wrote:
>
>
>> >
>> You need a reference point to set to zero, it could be anything but
>>
>> average velocity would be convenient , its the reference frame that shows
>>
>> zero dipole moment in the Cosmic Microwave Background.
>
>
> >
> *The average velocity of everything you can see being set to zero is
> less convenient and less sensible than setting your own velocity to zero. *
Copernicus would have disagreed with you and so would Kepler who found it
vastly more convenient to set the sun's motion as zero rather than that of
the Earth when he calculated the motion of Mars.
>* *
> *Let me get this straight. You concede the existence of stuff you can't
> see gravitationally attracting you*
Not
gravitationally attracting
me but
gravitationally attracting
something that I can see. If I see a galaxy 12 billion light years away
move in an odd way I might conclude that something more distant than 13.8
billion light years, which is the limit of what I can see, is pulling on it
gravitationally
. Or if I observe a large blemish in CMB (which we have not) I might even
conclude that our universe had collided with another universe I can not
see.
> >* *
>
>
> *but you don't concede the existence of an event horizon at the Hubble
> radius when that event horizon is precisely the reason you can't see the
> stuff that is attracting you?*
Things at the Hubble radius
aren't at a event horizon they are at a causal horizon (sometimes called a
absolute horizon), the two things are related but not identical, one is a
subset of the other. All event horizons are
are causal horizons but not all causal horizons are event horizons. I may
or may not be inside a event horizon
,
if I am then I'm heading toward a singularity and there is no way to avoid
it, but I'm
most
certainly inside a causal horizon because everything is
,
but I'm not necessarily heading toward a singularity. I can't send
information outside
what you call a
causal horizon
but I might be able to see things beyond it or at least deduce information
about it; this asymmetry is do to the accelerating expansion of the
universe, things are moving away from me faster now than they were long ago.
But if I'm inside a event horizon I'm completely cut off from anything
outside it.
However the two types of horizons are similar enough that l
ike a Black Hole's event horizon the causal horizon of the universe also
has a temperature and also gives off radiation, it's called
Gibbons–Hawking
radiation, but unlike a Black Hole's Hawking radiation the universe's
Gibbons–Hawking
radiation does not change with time.
The universe is doubling in size every 12.2 billion years, so after 850
billion years the CMB will have a wavelength of 22 billion light years and
be too weak to be important
,
but the background temperature will never be zero because the
Gibbons–Hawking effect
will start to dominate
then
. The universe will never get any colder than 7*10^-31 K
thanks to the
Gibbons–Hawking effect
, that's very cold but its not absolute zero.
>
> *You *can't* set the universe's average velocity to zero. You don't
> know how big it is.*
I know how big the observable
universe is and I can set that to zero, it is the only reference frame
that doesn't show a dipole pattern in the CMB.
> >* *
> *a dimensionless constant, I shall call S. S:= H^2*Tp^2 = H^2*h*G/c^5 or
> approximately 1.4*10^-122 where H is the Hubble parameter and Tp is the
> Planck time, h is the reduced Planck's constant, G is the gravitational
> constant, and c is the speed of light.*
>
I checked your math and you're right, the units check out and it is indeed
dimensionless
.
I get a number closer to *1.9*10^-129*, but the accepted value of the the
Hubble's constant H
has changed lot in just the last few years and we may have been using
different values, and you're taking the square of it. In
meter-kilogram-seconds units
I figured the
Hubble's constant H is
1.
62*10^-18 s^-1 (although I wouldn't bet much money on the accuracy of the
last of those 3 digits, or even on the last two)
so
:
H^2 is *2.6*10^-36 s^-2*
*. *
The Plank constant h is *2.6*10^-36 ** (m^2) (kg/s)*
The gravitational constant G is *6.8*10^-11 m^3/kg*s^2*
The speed of light c is
3*10^9
m/s so c^5 is *2.43 *10^47 m^5/s^5*
So
H^2*h*G/c^5
=
[
2.6*10^-36
]
[
2.6*10^-36
]
[
6.8*10^-11
]/
[
2.43 *10^47
]
=
* 1.89*10^-129*
In
addition to the uncertainty in the Hubble constant the
Gravitational constant is known to only 6 significant digits
and the
Planck constant is only known to only 9 significant digits.
And we're talking about 122 digits
, or maybe 129.
Also the
Hubble
constant
has the name it does for historical reasons but we now know the
Hubble
"constant" is not a constant, it
is a time dependent
variable, a function
of the
CMB red-shift.
Therefore
your value S can't be a constant either, but as far as we know the density
of Dark Energy is constant, so it doesn't work.
And most important of all
,
did you have a physical reason for coming up with
(
*H^2)*h*G/c^5 *or did you just pick it because if gave you a number
you liked?
John K Clark
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