Wednesday, February 22, 2023

3882 - DARK MATTER SECRETS -

 

-  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                                                                                                                          

---------------------------------------------------------------------------------------

-----  Comments appreciated and Pass it on to whomever is interested. --

---   Some reviews are at:  --------------     http://jdetrick.blogspot.com --

--  email feedback, corrections, request for copies or Index of all reviews

---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  --------

--------------------- ---  Wednesday, February 22, 2023  ---------------------------

 

 

 

 

         

 

-

 

 

 

 

           

 

 

No comments:

Post a Comment