Stargazers spot dark energy

"Doug Freyburger" wrote in message
...
Wayne Throop wrote:

::: To result in an 'increased rate of separation' they either need to
::: REPEL each other or be under some other form of acceleration.

:: Really?

Yes.

No. That's the deal with the expanding universe. The amount of space
between here and there grows without any acceleration of either object.
The question is whether the accelerating expansion is because the amount
of space is growing faster or if there's now so much space between here
and there that there's more of it to expand.



Dark energy increased dramatically in the universe at the very
same time life evolved on Earth. Anyone care to speculate
on the source of that 'cosmic coincidence'?

And btw, gravity does NOT always attract, most forms of
matter are self-repulsive. Hence, the matter spreads itself
out as thinly as possible, making it rather difficult to spot
....hence the term dark.

But dark matter and energy cannot be directly observed, only
known by the ...effects, for the very same reason we can only
know things like market forces and gravity by their effects.
As they are all emergent system properties.

"Emergence and Evolution - Constraints on Form"

"Again on a Solar System or Galactic level interactions of a
different form (gravitational and electromagnetic) lead to emergent
structure, suggesting that the concept of 'external selection' is
simply a convenient simplification in what is always essentially
a two way process. Self-regulation by feedback mechanisms
seems to be a feature of every level of evolution, a hierarchy
of order, emergent from initial disorder."
http://calresco.org/emerge.htm


But what dark matter and dark energy are really telling us
is just how little we know. Don't for a minute think anyone
has a handle on reality. All the great discoveries are just
around the corner.

Everything is about to change.


Quotes below from the director of theoretical science
at Princeton, a founder of inflationary theory, and one
of the top cosmologists in the world.


A Quintessential Introduction to Dark Energy
Paul J. Steinhardt

(selected quotes)

"We live at a special moment in cosmic history: the transition
between a decelerating, matter-dominated Universe and an
accelerating, dark-energy-dominated Universe."

"Most of the energy in the universe consists of some form
of dark energy that is gravitationally self-repulsive and
that is causing the expansion rate of the universe to
accelerate."

"Most of the energy in the universe is not "matter."
For its first 300 years, physics has focused on the
properties of matter and radiation, including dark matter.
Now we know that they represent less than 30%
of the composition of the universe. The rest consists of
something we know virtually nothing about."

"Most of the energy in the universe is not gravitationally
attractive. We are probably the last generation to have
been taught that gravity always attracts,"

"Why did the Universe begin to accelerate just as humans
started to evolve? Cosmic acceleration and human evolution
are both linked to the onset of matter domination. The k-essence
component has the property that it only behaves as a negative
pressure component after matter/radiation equality, so that it can
only overtake the matter density and induce cosmic
acceleration after the matter has dominated the Universe
for some period, at about the present epoch."

"The two logical possibilities for dark energy are the
cosmological constant and quintessence. The cosmological
constant was first introduced by Einstein for the purpose of
constructing a static model of the universe."

"Quintessence is a dynamical, evolving, spatially
inhomogeneous component with negative pressure."
"In the current context, quintessence would be the fifth
dynamical component that has influenced the evolution
of the universe, in addition to the previously known
baryons, leptons, photons, and dark matter.

"If space is uniform, then should not the same be true for time?
Hubble's discovery that the Universe is expanding taught us
that the Universe is evolving, but the notion was that the
evolution has been steady over the last 15 billion years
with no remarkable changes. We now know that time
is anti-Copernican."


Fine-tuning, cosmic coincidence, and the quintessential solution

"Whatever form the dark energy takes, two new cosmological
problems arise. First, the component must have a tiny energy
density (ca. 10¡47 GeV4) today. How does this small value
arise from a microphysical theory? We will refer to this
puzzle as the Fine-tuning problem'."

"A second problem arises when the cosmological model is
extrapolated back in time to the very early Universe, at the end
of inflation, say. The quintessence energy density decreases at a
different rate from the matter density, and their ratio shrinks
by many orders of magnitude as we extrapolate back in time.
The observations tell us that, somehow, the ratio was set initially
just right so that now, fifteen billion years later, the ratio is of
order unity. Accounting for the special ratio in the early Universe
will be referred to as the `coincidence problem' (Steinhardt 1997)."

"The fine-tuning and cosmic coincidence problems are vexing.
They are often posed as a paradox: why should the acceleration begin
just as humans evolve? In desperation, some cosmologists and
physicists have given renewed attention to anthropic models."

"Should we believe, as most cosmologists suggest, that this
is the last missing piece of the puzzle and our understanding of
the universe is virtually complete? Or have we just uncovered
a deep dark secret that will revolutionize our whole view
of the universe and our place in it? I must confess to my own
prejudice that the latter seems more likely."
http://www.physics.princeton.edu/~steinh/steinhardt.pdf


The key words on all of the above is ...."in desperation"

He's correct in that last assumption. Our view of the universe
is about to /completely/ change.

The stunning 'cosmic coincidences' require an entirely
different world view to explain. The fundamental constants
of the universe /must evolve/ to explain the observations.

Just as the larger sample better shows the underlying
patterns of behavior, the most complex the universe
has to offer best shows fundamental law. And the
most complex the universe has to offer is...LIFE!

Life explains the universe
not the other way around.

Assuming that reducing to the simplest parts the universe
for fundamental law is an erroneous assumption driven
out of necessity, not logic.


Jonathan


s

"David Spain" wrote in message
...
Doug Freyburger wrote:
Wayne Throop wrote:

::: To result in an 'increased rate of separation' they either need to
::: REPEL each other or be under some other form of acceleration.
:: Really?
Yes.

No. That's the deal with the expanding universe. The amount of space
between here and there grows without any acceleration of either object.
The question is whether the accelerating expansion is because the amount
of space is growing faster or if there's now so much space between here
and there that there's more of it to expand.

And I can't help but believe this is also intertwined with the 2nd Law Of
Thermodynamics. We are not only expanding, we are cooling too.


The universe initially inflated from radiation pressure. As the ratio
of matter increased, the rate of inflation slows. But just recently, at
about the same time life on Earth evolved, the universe arrived
at the tipping point between radiation/matter equality. At this tipping
point a ...new force for a second period of universal inflation
greatly increased...dark energy. Which is self repulsive, providing
the force for this second round of inflation. Dark energy existed before
this tipping point, but at minuscule levels. And dark energy will
dissipate quickly after the tipping point, as it's unstable.

But near the tipping point, dark energy becomes a primary
variable for the future evolution of the universe.

This universe-wide balance between energy and matter
coincides with a second, but much slower, period of
inflation due to the emergence of self-repulsive dark energy.
Also coinciding with the start of life on Earth.

Dark energy and life?
Cosmic coincidence?
Or cause and effect?

The question then becomes, how in the world
could the state of the distant reaches of the
universe effect the evolution of life on Earth?

How is life connected to the cosmos?
We'll never understand the co-evolutionary
relationship with physics, but only through...Darwin.

Just pretend that's in fact true, for a moment, and
try to imagine the implications for science
and religion. For a new world-view.
That biological evolution is just as pervasive
and inherent to the universe as gravity.

After all, gravity and fitness follow inverse-square
law behavior. Why shouldn't there be a universal
process of evolution?


s



Dave (now colder than when I started typing this) Spain

Jonathan wrote:
Stuff from Steinhardt...

I like Steinhardt, I mostly agree with him; Physics is at another one of those
major crossroads, like it was back in the late 19th century. You know, 19th
century physicists also believed that with Maxwell's equations and the work of
Newton all behind us it was just a simple matter of mopping up the remaining
spots and gathering the results of the Michelson-Morely experiments to fill in
the holes and determine where our inertial reference frame was in regards to
the universal frame.

But unlike Steinhardt, I'm not worried about 'Quintessence'.

We need to study and think hard about what could be going on near and around
the Planck 'interval'. My money is on positive quantum vacuum energy. This
would force an expanding universe, and probably an accelerating one at that,
sets the direction for the arrow of time to be 'away from quantum foam',
forces the 2nd Law of Thermodynamcs, and dooms the ultimate fate of the
universe to be devoid of energy, since space-time will eventually face what
I'd call 'destructure' and cannot support it.

My 2 cents...

Dave

In alt.philosophy David Spain wrote:
....
We need to study and think hard about what could be going on near and around
the Planck 'interval'. My money is on positive quantum vacuum energy. This
would force an expanding universe, and probably an accelerating one at that,
sets the direction for the arrow of time to be 'away from quantum foam',
forces the 2nd Law of Thermodynamcs, and dooms the ultimate fate of the
universe to be devoid of energy, since space-time will eventually face what
I'd call 'destructure' and cannot support it.
....

There may be something to the idea. If you look at the mathematics of
random walks -- a simple example is the scenario of a drunk on a bridge;
1/2 the time staggering toward one shore, 1/2 the time to the opposite
shore -- you find that in 1D (i.e. the bridge example) the "average
position" of the drunk remains where they started; in 2d (the
"drunk on the playground" the same; but in 3d and higher the average
position drifts away from the starting point.

The same kind of thing -- or possibly some more arcane consequence of
the relevant mathematics -- happening at small scales or even cosmological
scales could account for an expansion "force".

Similarly, there may also be a "quantum" explanation for the "dark matter" --
perhaps some analog of gravitation related to zero-point energy.
Of course, the cosmos itself may be warped without the need for
any mass/energy (or other) to do the job.

--
They said it was only luck. But the more I practised, the luckier I got.
-- Gary Player [and others]