Re: Dark matter/energy - is it real?
- From: "Tue Sorensen" <sorensonian@xxxxxxxxx>
- Date: 2 Apr 2006 17:20:37 -0700
Erik Max Francis wrote:
Tue Sorensen wrote:
Let's say I was sceptical about the existence of dark matter and dark
energy - how would you convince me that it's there?
It is mentioned here, for instance:
http://physicsweb.org/articles/news/10/3/22/1
"we are living in a flat universe comprising just 4% ordinary matter,
22% dark matter and 74% dark energy -- in agreement with the standard
model of cosmology."
Dark matter is apparently supposed to be some form of non-luminescent
matter, but what is dark energy supposed to be?
The existence of dark matter is inferred by, among other things, looking
at galactic rotation curves. We can see galaxies spinning, and we can
measure how fast the matter in them is moving (due to Doppler shift).
By doing this, we see that they're moving much faster than they would be
if only the glowing matter we see were there. That is, if our theories
of gravity are anything like correct, there must be a lot of matter
there we can't see.
If our theories are correct... What about our own galaxy? Are there
measurements of the rotation of the Milky Way, showing that our galaxy
contains just as much dark matter as the other ones we've observed?
This really isn't all that surprising; the fundamental concept of dark
matter is not all that mysterious. Most of the matter around you
consists of dark matter: It does not emit its own light. (It may be
warm now compared to interstellar space, but that's only because it's in
equilibrium with its surroundings; if it were put in deep space it would
rapidly cool far below direct detectability.) In some frequencies, even
_you_ are dark matter.
And yet, I'm told that planets and dust left over from dead solar
systems cannot account for all the dark matter. It seems to be assumed
that the majority of dark matter is some very different form of matter
(like tiny, tiny, very, very numerous particles); something exotic and
not yet known. (Of course, for all we know it could all be space
habitats constructed by other civilizations...)
Dark energy is a more recent discovery (and is named to be similar to
dark matter even though it's not necessarily a related phenomenon).
Careful measurements of the rate of expansion of the Universe show that
instead of the expansion slowing as you'd expect from gravity, it is in
fact accelerating. Thus there must be some force that is causing it to
expand; this force is named dark energy.
OK. The force that makes the expansion accelerate. I think it ought to
have a better name. How about Dark Force...? Or would that piss of
George Lucas? :-)
It acts like a cosmological
constant -- the thing Einstein added to his cosmology to try to make the
Universe steady state, but which later regretted. Dark energy is
certainly weirder than dark matter, but here too it is not totally
unprecedented: We're pretty sure that the Universe looks as flat as it
does because early on it went through a period of inflation, which was
also equivalent to having a nonzero cosmological constant.
If the universe is not in a steady state, do we need a cosmological
constant?
Dark matter and energy are really only the names we give to phenomenon
that we can logically conclude must be taking place if our understanding
of gravity and matter (and so on) are remotely correct. So far they are
extremely good theories, and so we are confident that _something_ is
going on which we're not seeing directly. This is perfectly valid
science and happens all the time; the existence of the neutrino was
inferred since some radioactive decays appeared to be violating
conservation of energy. Rather than conclude that conservation of
energy is wrong after all, it makes much more scientific sense to
conclude that a particle that wasn't being detected was carrying away
that energy.
Yes - valid until it goes too far off on a tangent... I think our
theories do need some serious tweaking in key places.
What would happen to the
calculations if the speed of light was variable over vast distances
(which we are currently unable to measure)? If the force of gravity was
variable on the large scale?
The speed of light somehow changing would result in all sorts of
detectable effects which we don't see -- after all, this would affect
spectra significantly.
But would we know?
To explain away dark matter _and_ energy, the
force of gravity wouldn't have to just change, it would have to reverse
at large scales in bizarre ways that would probably be hard to make
consistent. (You'd also probably have to explain why our current
understanding of gravity coincidentally works so well despite being so
wrong.)
OK. Forget for a moment the standard model. Let's say that the original
form of energy, or force, from which *everything* is made up, only has
a single variable property determining its nature: its progression in
time. Progressing fast in time, it is EMR (high-energy), and
progressing slowly in time it is matter (low-energy). And lets further
say that the ground state of existence, before and outside of the
universe, is a constantly fluctuating very high-energy state of
superpositional gamma-radiation (or something pretty near to it).
As this fluctuating exo-cosmic unified energy/force, which I will call
"protean energy" because it is capable of taking many forms, reaches a
certain threshold of low energy (slow progress in time), a tiny portion
of it becomes a physical particle, a proton let's say. This triggers
the big bang and the initial inflation period. A pocket of (s)low-state
protean energy chain-reacts, because once you have protean energy
inside the pocket of slow time provided by the first particle and its
concommitant tiny amount of dimensional space, that energy will be
slowed down further, causing "phase transitions" en masse from
superpositional radiation to protonic matter in a spectacular collapse
of wave functions. Thus the beginning of the universe comprised a
massive time-brake, converting a bunch of energy to matter and the
space/gravity to go with it (and leaving a lot of EMR, too), creating a
temporally slow universe compared to the fast-time protean energy
continuum outside its edges.
Basically, matter associates to slow progression of time. The more
matter, the slower the time. This blends in well with relativity (look,
for instance, at the time it takes to be swallowed up by a black hole).
So what is happening in the universe since the initial, time-braking
inflation era is that universal time is slowly but inexorably being
speeded up again - hence the accelerated expansion. Matter
disintegrates in stars, and new energy is let into our universe from
the edges, where spatial density breaks down to re-connect with the
protean energy continuum, causing gamma-ray bursts (no, I don't
subscribe to the super-nova theory). Thus, as matter is more and more
exhausted, its influence diminishing, the universe is on its way to the
big rip; its reabsorption into the protean energy continuum. As this
process accelerates, more and more energy will enter our universe, and
matter will become increasingly insignificant (and space itself less
and less dense), until everything is reabsorbed, becoming once again
fast-time high-state protean energy.
I think this theory (which replaces dark energy with an "external
energy pull" from the protean energy continuum outside of the edges of
our universe's normalspace) has a lot of explanation power. And also
the potential to reform a lot of aspects of relativity. I actually came
up with this theory *before I heard about the accelerating expansion* -
which my theory predicts!
Interestingly, the theory also implies that if an intelligent species
wants to prolong the lifespan of the universe, it must produce as much
extra matter as it can, to slow down the accelerating expansion. If we
want to make the universe eternal, we might one day be able to, by
producing enough matter to make the universe stable. Maybe this is what
other civilizations are in the process of doing, by adding copious
amounts of a substance that we have had no choice but to call "dark
matter". Maybe.
And maybe not. It's just an idea. But the overall theory does suggest
that our ideas of entropy are skewed, since both the origin and the
approaching end of the universe have to do with extreme high-energy
states. According to my theory, the complete energy of the universe is
not constant; it is increasing. And instead of fusionable matter just
turning to baser matter, the dominant evolution of the universe can be
found in the energy into which matter is transformed in the hearts of
stars. The more unequal the balance between matter and energy becomes,
and the more in favor of energy, the faster the universe will expand.
Because the progress of time speeds up. In the end, things will be
going *very* fast indeed...
By this theory space and gravity are one and the same, corresponding to
a "spatial density" defined by the rate at which activity will occur
there, dependant on how close you are to how much matter. When you are
very far from any matter, spatial density becomes so thin that
normalspace breaks down, removing the extant edge between our universe
and the exo-cosmic protean energy continuum. Thus, it should eventually
be possible to invent technology that artificially generates a very
thin or low spatial density, and so can tap the protean energy
continuum itself for unlimited energy. Hence my other post on the
possibility of an effective perpetual motion engine.
Well, what do you think of the theory?
- Tue
.
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