Chapter
2
Science first
2-1
Dark matter, a dark corner
We are
now going to pry into a dark corner and come across remarkable
data. By first letting science have its say, we clearly see that
this corner
of the ‘corner of knowledge’ bases everything on assumptions
as there is
hardly any evidence, if any at all! Worse still, they do not know
what they
are talking about and they just make up a story around it.
So science first.
2-1
a
Dark matter
Dark matter
is a form of matter thought to account for approximately
85% of the matter in the universe and about 27% of its total mass–energy
density or about 2.241×10-27 kg/m3. Its presence is implied
in a variety
of astrophysical observations, including gravitational effects
that cannot
be explained by accepted theories of gravity unless more matter
is present
than can be seen. For this reason, most experts think that dark
matter is
abundant in the universe and that it has had a strong influence
on its structure
and evolution. Dark matter is called dark because it does not
appear
to interact with the electromagnetic field, which means it does
not absorb,
reflect or emit electromagnetic radiation, and is therefore difficult
to detect.
Primary evidence for dark matter comes from calculations showing
that
many galaxies would fly apart, or that they would not have formed
or would
not move as they do, if they did not contain a large amount of
unseen matter.
Other lines of evidence include observations in gravitational
lensing and in
the cosmic microwave background, along with astronomical observations
of the observable universe’s current structure, the formation
and evolution
of galaxies, mass location during galactic collisions, and the
motion of
galaxies within galaxy clusters. In the standard Lambda-CDM model
of
cosmology, the total mass–energy of the universe contains
5% ordinary
matter and energy, 27% dark matter and 68% of a form of energy
known
as dark energy. Thus, dark matter constitutes 85% of total mass,
while
dark energy plus dark matter constitute 95% of total mass–energy
content.
Because dark matter has not yet been observed directly, if it
exists, it
must barely interact with ordinary baryonic matter and radiation,
except
through gravity. Most dark matter is thought to be non-baryonic
in nature;
it may be composed of some as-yet undiscovered subatomic particles.
The primary candidate for dark matter is some new kind of elementary
particle that has not yet been discovered, in particular, weakly
interacting
massive particles (WIMPs). Many experiments to directly detect
and study
dark matter particles are being actively undertaken, but none
have yet succeeded.
Dark matter is classified as “cold”, “warm”,
or “hot” according
to its velocity (more precisely, its free streaming length). Current
models
favor a cold dark matter scenario, in which structures emerge
by gradual
accumulation of particles.
Although
the existence of dark matter is generally accepted by the scientific
community, some astrophysicists, intrigued by certain observations
which
do not fit some dark matter theories, argue for various modifications
of the
standard laws of general relativity, such as modified Newtonian
dynamics,
tensor–vector–scalar gravity, or entropic gravity. These
models attempt to
account for all observations without invoking supplemental non-baryonic
matter.
