A few years ago the accepted idea was that gravity was
going to gradually slow Universal expansion over time. This was all just talk since no one
had any proof that the Universe had begun to recoil in on itself. However in the
year 1998 the Hubble Space Telescope found that a supernovae in the distance
proved that today the Universe is expanding faster than it was in the past.
This defies all the logic of gravity since gravity pulls everything together
not apart. There were then three ideas proposed, Albert Einstein’s unaccepted proposition of a Cosmological constant. Which is essentially the constant that
explains that space is filled with some kind of energy. It is still unknown
whether Einstein was in fact correct however, today we are given a name to the
really unknown explanation and that is dark energy.
Dark energy is
really not a known thing as stated it is a name given to an unknown. The only
fact that is proven is that it is the reason for the Universal expansion. The weirdest thing is that Dark energy makes
up a huge 68% of the entire Universe. Dark matter is equated to about 27%, and
the stuff that is physical and observable on Earth makes up only about 5%.
Einstein said
that empty space is not just a bunch of nothingness. He though that dark energy
could just be the energy that empty space posses. Actually, dark energy could just be one of
the properties of the weird and wonderful space . Dark energy would
come in good company with the other strange space properties like space can
just become, it can just pop up out of the blue (as far as we know today). This
being said, if space is constantly growing then the amount of energy would also
increase which leads to the theory that this increase in energy also leads to
faster Universal expansion.
The theory that
dark energy is just a new kind of dynamical energy field, describes how dark energy basically fills
space with the opposite effect of normal energy – aka it makes the universe
expand instead of shrink. The people who came up with this actually went as far as labeling it quintessence. But, still the unknowns pile up and quintessence is unable to fully be explored, leaving gaps like
why it even exists.
If we really want
to throw out all the possibilities we could say that Einstein was wrong in his
theory of gravity. This would lead to new theories, which would have to provide
a solution to fit dark energy into the gravity equation. The problem is that we
do not have any of logical theories, and it would be hard to come up with
something so broad that will describe both dark energy and the effects of
gravity. *Some theories exist but none appear at all correct.
If you recall the
Quantum section, it too has a theory. Proposing that in empty space there are
temporary particles that form and then disappear over and over. The
calculations for this theory were so wrong however that it is not really the
favoured theory – and just makes dark energy a problem even to some of the
people looking at very strange physics.
So, now that I’ve
rambled on about dark energy you are likely wondering about dark matter. I can
tell you that dark matter is not stars or planets, it is not made of the
baryons clouds like normal matter, it does not interact with any
electromagnetic forces, it never will absorb or reflect light (therefore we
cannot see it), it is not some large
black hole , and it is also not antimatter.
Fritz Zwicky
discovered the gravitational effects of dark matter way back in the 1930s as he
was studying the Coma Cluster and the movement of galaxies within this cluster.
There are about 1000 galaxies in the Coma Cluster. Gravity is said to hold the
galaxies in this cluster. So, how did his research lead to dark matter? When he
looked at the total light output and compared it to the mass of the Cluster the
ratio was not adding up to that of the Kapteyn stellar system (the amount of
light was less than one single Kapteyn star). This means that the cluster would
need to have some unaccounted matter and this matter must be dark
matter. At the time this was not one of the main issues, scientists were still
worried about other more pressing matters and put the dark matter issue to the
side for awhile.
You’re wondering;
if we cannot see it how are we so sure it exists. For one I just got done
talking about dark energy and it’s effect of gravity, well dark matter has an
effect on normal, visible matter.
So what in the
world is dark matter? There are theories, for instance dark matter could be
made of weird things like axions, or it could be a hidden form of
baryonic particles shielded in dense masses of other elements. This is what is
referred to as massive compact halo object.
Maybe the
strangest thing about dark matter is that it is seen as such an abundant thing
that it could literally be passing through/by us every single second. The
problem is that is does not have any strong interactive properties, not even
with other dark matter. The fact is that
it is hard to study, but also it could literally be anywhere or everywhere however
we would not know with the naked eye if it were actually right next to us this
very moment.
http://ngm.nationalgeographic.com/2015/01/hidden-cosmos/ferris-text
https://www.learner.org/courses/physics/unit/text.html?unit=10&secNum=2
http://www.symmetrymagazine.org/sites/default/files/images/standard/Feature_DarkMatter3.jpg
http://astronomer.wpengine.netdna-cdn.com/wp-content/uploads/2014/09/DMPie_2013.png
http://www.abmedia.com/astro/CCDMono/Coma-Cluster-130EDF.jpg
http://www.abmedia.com/astro/CCDMono/Coma-Cluster-130EDF.jpg
