- 3882
- DARK
MATTER SECRETS - Space probes that fly close to the sun
might one day help to reveal the nature of “dark matter”. Dark matter is the invisible and largely
intangible substance that researchers suggest makes up about 80% of all matter
in the universe. “Ordinary Matter” is
only 5%.
-------------------- 3882 -
DARK MATTER
SECRETS -
-
- Although
dark matter hasn't been observed directly, its existence is discovered via its
gravitational effects on the movements of stars and galaxies. What dark matter
might be composed of remains a 80% mystery.
-
- A new way to
discover the nature of dark matter uses the most precise timepieces ever made:
atomic clocks. Currently, the best
atomic clock is so precise, it will essentially lose just one second every 300
billion years.
-
- Atomic
clocks are sent into space regularly.
GPS satellites rely on atomic clocks to broadcast precisely timed
messages that each GPS receiver uses to help pinpoint its location.
-
- The
physicists suggest that a “SpaceQ mission” in an orbit near the sun could
measure this dark matter. The Parker
Solar Probe came closer to the sun than
any other spacecraft had gone before. In 2021, the probe flew across the sun's
corona for the first time, and it continues to circle closer and closer to our
star.
-
- Leading
candidates for dark matter include ghostly ultralight particles. For instance,
a hypothetical particle known as an “axion” may have a mass less than a
billionth of an electron's.
-
- If dark
matter is made of ultralight particles, their insubstantial nature would make
them extraordinarily difficult to detect, explaining why they have eluded
discovery to date.
-
- However,
because the sun is far heavier than Earth, about 330,000 times the mass of our
planet, it possesses a stronger gravitational pull. In principle, this means
the sun may collect significantly more dark matter to it than Earth does. This
greater density could make it easier for probes near the sun, closer than
Mercury's orbit, to detect these ghostly
particles.
-
- Waves of
ultralight dark matter particles could trigger variations in fundamental
constants of nature, such as the mass of the electron or the strength of the
electromagnetic force. This, in turn, would change how atomic clocks tick, an
effect that depends on the atoms the clock uses.
-
- By
comparing how two different atomic clocks keep time near the sun, researchers
may find dark matter. Comparable effects also may be seen in future timekeepers
that may prove even more precise than atomic clocks, such as so-called nuclear
clocks.
-
- The SpaceQ
mission would require clocks that are still under development. In addition,
even if it detected dark matter signals, researchers would need independent
experiments to verify its findings.
-
- Dark matter
is the invisible and largely intangible substance that researchers suggest
makes up about five-sixths of all matter in the universe. Although dark matter
hasn't been observed directly, its existence is hinted at via its gravitational
effects on the movements of stars and galaxies. What dark matter might be
composed of, however, remains a mystery
-
- An axion
may have a mass less than a billionth of an electron's. Theoretical physicists
originally proposed the existence of axions to help explain why interactions
are seen between some particles but not others.
-
- Scientists
find first evidence that black holes are the source of dark energy February
15, 2023. Observations of supermassive black holes at
the centers of galaxies point to a likely source of dark energy. The measurements from ancient and dormant
galaxies show black holes growing more than expected, aligning with a
phenomenon predicted in Einstein's theory of gravity.
-
- The result
potentially means nothing new has to be added to our picture of the Universe to
account for dark energy: black holes combined with Einstein's gravity are the
source. If the theory holds, then this
is going to revolutionise the whole of cosmology, because at last we've got a
solution for the origin of dark energy that's been perplexing cosmologists and
theoretical physicists for more than 20 years.
-
- In the
1990s, it was discovered that the expansion of the Universe is
accelerating. Everything is moving
away from everything else at a faster and faster rate. This is difficult to
explain. The pull of gravity between
all objects in the Universe should be slowing the expansion down.
-
- To account
for this, it was proposed that a 'dark energy' was responsible for pushing
things apart more strongly than gravity. This was linked to a concept Einstein
had proposed but later discarded, a 'cosmological constant' that opposed
gravity and kept the Universe from collapsing.
-
- This concept
was revived with the discovery of the accelerating expansion of the Universe,
with its main component being a kind of energy included in spacetime itself,
called “vacuum energy.” This energy pushes the Universe further apart,
accelerating the expansion.
-
- Black holes
posed a problem though their extremely strong gravity is hard to oppose,
especially at their centers, where everything seems to break down in a
phenomenon called a 'singularity'.
-
- The new
result shows that black holes gain mass in a way consistent with them
containing vacuum energy, providing a source of dark energy and removing the
need for singularities to form at their center.
-
- The
conclusion was made by studying nine billion years of black hole evolution.
Black holes are formed when massive stars come to the end of their life. When
found at the centers of galaxies, they are called “supermassive black holes”.
These contain millions to billions of times the mass of our Sun inside them in
a comparatively small space, creating extremely strong gravity.
-
- Black holes
can increase in size by accreting matter, such as by swallowing stars that get
too close, or by merging with other black holes. To discover whether these
effects alone could account for the growth of supermassive black holes.
-
- The
researchers looked at a particular type of galaxy called “giant elliptical
galaxies”, which evolved early in the Universe and then became dormant. Dormant
galaxies have finished forming stars, leaving little material for the black
hole at their center to accrete, meaning any further growth cannot be explained
by these normal astrophysical processes.
-
- Comparing
observations of distant galaxies (when they were young) with local elliptical
galaxies (which are old and dead) showed growth much larger than predicted by accretion
or mergers. \The black holes of today
are 7 to 20 times larger than they were nine billion years ago.
-
- Further
measurements with related populations of galaxies at different points in the
Universe's evolution show good agreement between the size of the Universe and
the mass of the black holes. These show that the measured amount of dark energy
in the Universe can be accounted for by black hole “vacuum energy”.
-
- This is the
first observational evidence that black holes actually contain vacuum energy
and that they are 'coupled' to the expansion of the Universe, increasing in
mass as the Universe expands, a phenomenon called 'cosmological coupling'. If
further observations confirm it, cosmological coupling will redefine our
understanding of what a black hole is.
-
- What that
means is not that other people haven't proposed sources for dark energy, where
we're not adding anything new to the Universe as a source for dark energy:
black holes in Einstein's theory of gravity are the dark energy.'
-February19, 2023 DARK MATTER SECRETS 3882
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------ “Jim Detrick” --------
---------------------
--- Wednesday, February 22, 2023 ---------------------------
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