- 4570
- DARK MATTER ALTERNATIVES - Dark matter is thought to account for 85% of
mass in the Universe, but because it barely interacts with ordinary matter and
doesn’t interact at all with light, it is notoriously difficult to observe
directly. Several research teams have tried to catch a glimpse of the elusive
substance, but only the DAMA/LIBRA experiment has claimed to have seen it for
real.
-
------------------------------------- 4570
- DARK MATTER
ALTERNATIVES
-
- It’s a mystery that has had physicists
scratching their heads for more than 20 years. The DAMA/LIBRA experiment at the
Gran Sasso National Laboratory (LNGS) near L’Aquila, Italy, has been recording
an annual fluctuation of light flashes in its detector that appears to be a
sign of dark matter. But no one has been able to definitively replicate the
findings.
-
- DAMA/LIBRA’s observations of the distinct
annual pattern is consistent with what physicists would expect with Earth’s
relative position in the galaxy throughout the year. As the Earth orbits the
Sun, the Sun orbits the black hole at the center of the Milky Way.
-
- In June, the Earth hurtles through the
Milky Way in the same direction as the Sun, increasing its relative speed
through the haze of dark matter. But in December, the Earth travels with the
flow of dark matter as it moves in the opposite direction to the Sun. As
expected, the number of signals recorded by DAMA/LIBRA’s detector are highest
in June and lowest in December.
-
- A handful of groups have attempted to
reproduce DAMA/LIBRA’s results using similar methods and materials in their
detectors, including the same type of sodium iodide crystals that emit tiny
flashes of light when they are hit with subatomic particles. Among them is
COSINE-100, which has been running since 2016 at Yemilab’s predecessor, the
Yangyang Underground Laboratory (Y2L) in South Korea.
-
- But none have produced results that match
those of the original experiment, raising questions about whether the yearly
swing in signals is because of something else, such as the detector itself or
from errors in the analysis methods used.
This is a puzzle that’s still there after 20 years.
-
- Although the COSINE-100 detector uses the
same type of sodium iodide crystals, they contain up to three times more
radiation than the ones used in DAMA/LIBRA, which can muddy the faint signals
of potential dark-matter particles and make it difficult to produce definitive
results.
-
- The upgraded experiment will use the same
crystals as those used in the earlier COSINE-100 experiment, but with some
extra enhancements to boost their sensitivity. The team are also developing a
set of sodium iodide crystals that will be even more radiopure than
DAMA/LIBRA’s for the next phase of the experiment, COSINE-200.
-
- “COSINE-100” will be housed in the brand
new 3,000-square-metre Yemilab. The $23 million facility lies around 1
kilometer underground and surpasses Y2L in both depth and volume. Since
September 2023, researchers have been moving all Y2L experiments to Yemilab,
where they will begin their next phase by the end of this year.
-
- Yemilab also offers a better-shielded
environment for detecting elusive particles besides dark matter. The facility
will also hunt for neutrinos, chargeless particles that barely have mass.
-
- The second phase of an experiment called
“AMoRE” will search for signs of two neutrons decaying into protons and
electrons without emitting a neutrino. This hypothesized process is called
“neutrinoless double β decay” and if observed, it will demonstrate that
neutrinos are their own antiparticle.
-
- This could offer clues about their mass and
explain why there is more matter than antimatter in the Universe. The upgraded neutrino detector will use
around 160 kilograms of crystals embedded with molybdenum-100, a naturally
occurring radioisotope. When AMoRE-II starts running at the end of this year,
it will be 100 times more sensitive than the previous version of the
experiment.
-
- Whether the two experiments succeed or fail
at detecting the rare events they are looking for, they are nevertheless set to
raise more questions. If both will
deliver only null results, we should seriously start rethinking the Universe.
-
- We need to consider alternatives to dark
matter that better explain cosmological observations. Do constants of nature—the numbers that
determine how things behave, like the speed of light—change over time as the
universe expands? Does light get a little tired traveling vast cosmic
distances?
-
- It was believed that dark matter and dark
energy explained these cosmological phenomena, but recent research indicates
that our universe has been expanding without dark matter or dark energy. Doing away with dark matter and dark energy
resolves the "impossible early galaxy problem," that arises when
trying to account for galaxies that do not adhere to expectations regarding to
size and age. Finding an alternative to dark matter and energy that complies
with existing cosmological observations, including galaxy distribution, is
possible.
-
- Dark matter is a hypothetical form of
matter that does not interact with ordinary matter in any way except through
gravity. It was proposed as a theoretical way to explain our astrophysical and
cosmological observations. Ordinary matter can travel through the dark matter
without any resistance and vice versa.
-
- In space, gravitational pull determines the
speed at which an object orbits. A higher speed than expected from surrounding
orbiting objects is attributed to the existence and gravitational pull of dark
matter.
-
- The gravitational pull of dark matter can
also bend light rays, causing a gravitational lensing effect just like normal
matter. This allows for the measurement of dark matter in the object causing
the bending, such as in galaxies and clusters of galaxies.
-
- The most robust support for the existence of
dark matter comes from the tiny variations observed in the cosmic microwave
background radiation (remnant radiation from the big bang), measured with
increasingly high precision.
-
- Another argument for the existence of dark
matter is that large-scale structures of the universe, such as galaxies, would
not be able to form without the dark matter within the limited age of the
universe.
-
- There are alternatives to dark matter that
account for many astrophysical observations. The oldest and most popular theory
is “modified Newtonian dynamic” (MoND), which suggests that the Newtonian
inverse square law of gravitational attraction force is a simplified version of
a complete force that becomes perceptible only at very large distances when
Newtonian force becomes negligible.
-
- Another alternative is a version of MoND
that includes Einstein's relativistic effects and explains observations where
MoND is limited, such as cosmic microwave background radiation. Then there is
the proposed theory of “retarded gravity” that also claims to comply with such
observations.
-
- Astronomers are surprised to learn that many
observations show a complete absence of dark matter or dark matter-deficient
structures. This leads one to question its existence. One then has to find an explanation of what
might have created the problem, such as tidal forces exerted by the passing of
nearby galaxies stripping away dark matter. Even the mass of the Milky Way has
recently been determined to be much smaller than expected from cosmology.
-
- Recent discoveries create doubt around the
existence of dark matter. Despite extensive research and billions of dollars in
investment, there has been no direct detection of any dark matter. The dark energy theory negates the
gravitational pull of matter, causing the universe to expand faster with time,
as observed.
-
- The interrelated variation of constants of
nature, dubbed “covarying coupling constants” (CCC), achieve the same effect by
weakening the gravitational pull and other forces of nature with time,
eliminating the need for dark energy.
-
- Combined with the “tired light” (TL) effect
which posits that light slows down as a result of energy loss, such a
cosmological model has no room for dark matter. The CCC approach could also
replace the dark energy-like constant considered responsible for the extremely
rapid expansion of the universe following the Big Bang, called “inflation”.
-
- The age of the universe is determined from
the historical expansion rate of the universe, and can vary depending on the
model used for the expansion. Measuring the redshift of exploding stars, called
supernovae type 1a, and their observed brightness can determine the expansion
rate of the Universe.
-
- Redshift is the lowering of spectral line
frequencies depending on the recessional speed of the emitting object, similar
to the frequency of a receding ambulance siren. By allowing the redshift due to
the tired light effect to coexist with the expansion redshift, the universe's
expansion rate is reduced, and age of the universe increases.
-
- This new model predicts the universe is
older than we think it is, 26.7 billion years in the CCC cosmology compared to
13.8 in the standard cosmology, and allows galaxies and their clusters to form
without dark matter. The increase in the age of the universe in early times
when structures started forming was up to 100 times larger in the new model.
-
- The absence of dark matter that reduces the
gravitational force and increases the time for collapsing the matter to form
structures is greatly overcompensated by increased age in the CCC model.
-
- The expansion of the universe causes time to
appear slowed down when observing distant galaxies. The CCC+TL model complies
with observations showing a time dilation effect that appears to slow down the
clock in distant objects.
-
- The standard cosmology model requires dark
matter to fit observations, such as accounting for redshift when measuring the
brightness of supernovae. Dark matter is also used to explain physical
processes such as galaxy rotation curves, galaxy clusters or gravitational
lensing. Using CCC+TL cosmology means that we must seriously consider
alternative physical processes to account for observations that had previously
been attributed to dark matter.
-
-
October 3, 2024 DARK
MATTER ALTERNATIVES 4570
------------------------------------------------------------------------------------------
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------
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------ “Jim Detrick” -----------
--------------------- --- Friday, October 4, 2024
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