4582 - RELATIVITY - The Evidence for Einstein's Theory?

 

-  4582 -   RELATIVITY  -  The Evidence for Einstein's Theory?  -   Albert Einstein's famous theory of relativity has been borne out in the real world, measured in eclipses, distorted galaxies and even the universe's structure.   The theory of gravity is general relativity (GR), first cooked up by Albert Einstein himself in a magnificent feat that took seven years to complete and provided amazing insights into how the world works.

---------------------------  4582  -  RELATIVITY  -  The Evidence for Einstein's Theory?

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-    It's easy enough to state the bare essence of the theory, "Matter and energy tell space-time how to bend, and the bending of space-time tells matter how to move." But the actual mechanics take a whopping 10 equations to describe, with each one very difficult and highly interconnected with the others.

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-  Out of all the features of his new theory, Einstein was proudest of its ability to explain the details of the orbit of Mercury. That innermost planet has a slightly elliptical orbit, and that ellipse ever-so-slowly rotates around the sun. In other words, the place where Mercury is farthest from the sun slowly changes with time.

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-    If you apply simple Newtonian gravity to the sun-Mercury system, this change over time, called “precession”, doesn't show up.    Isaac Newton's view is incomplete. Once you add in the gentle gravitational nudging and tweaking due to the other planets, almost all of the precession can be explained, but,  not all.

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-    By the early 1900s, it was a well-known problem in solar system dynamics, but not one that caused much controversy. Most folks just added it to the ever-growing list of "slightly weird things we can't explain about the universe" and assumed that we would find a mundane solution some day.

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-   But Einstein thought Mercury was giving him a clue. When, after years of attempts, he was able to flex his general relativistic muscles and explain precisely the orbital oddities of Mercury, he knew he had finally cracked the gravitational code.

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-    Before Einstein put the finishing touches on the big GR, he came to some startling realizations about the nature of gravity. If you're isolated on a rocket ship that accelerates at a smooth and constant 1g — providing the same acceleration as Earth's gravity does — everything in your laboratory will behave exactly as it would on the planet's surface.

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-    Einstein reasoned objects will fall to the ground at the same speed as on Earth; your feet will stay firmly planted on the floor, etc.  This equivalence between gravity (as experienced on Earth) and acceleration (as experienced in the rocket) propelled Einstein forward to develop his theory.

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-     But hidden in that scenario is a surprising insight. Imagine a beam of light entering a window on the left side of the spaceship. By the time the light crosses the spaceship to exit, where will it be?

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-   From the perspective of an outside observer, the answer is obvious. The light travels in a perfectly straight line, perpendicular to the path of the rocket. During the time the light was passing through, the rocket pushed itself forward. The light will then enter the rocket at one window, near the tip, and exit near the bottom, close to the engines.

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-   From the inside the spacecraft, though, things seem strange. In order for the light to enter a window near the tip and exit near the engines, the beam's path has to be curved. Indeed, that's exactly what you see.

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-   And since gravity is exactly the same as acceleration, light must follow curved paths around massive objects.

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-    It's difficult to observe this one experimentally, because you need a lot of mass and some light that passes close to the surface to get a detectable effect. But the 1919 solar eclipse proved just the right opportunity, and an expedition led by Sir Arthur Eddington found the exact shifting of distant starlight that Einstein's nascent theory had predicted.

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-   Another interesting result comes out of creative thought experiments surrounding general relativity. This conclusion relies on the good old-fashioned Doppler effect, but it's applied to an unfamiliar scenario.

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-   If something is moving away from you, the sound it produces will get stretched out, shifting down to lower frequencies.  That's the Doppler effect. The same is true of light: A car moving away from you appears ever-so-slightly redder than it would be if the vehicle were stationary. (The redder light, the lower the frequency.)

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-   Cops can take advantage of this shift by bouncing a light off your car to catch you speeding. If movement shifts light's wavelength, then acceleration can too: A bit of light traveling from the bottom to the top of an accelerating rocket will experience a redshift. And under GR, what goes for acceleration goes for gravity.  Light emitted from the surface of the Earth will shift down into redder frequencies the farther upward it travels.

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-   It took a few decades to conclusively demonstrate this prediction, because the effect is so tiny. But in 1959, Robert Pound and Glen Rebka proposed, designed, built and executed an experiment that enabled them to measure the redshift of light as it traveled a few stories up the Jefferson Laboratory at Harvard University.

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-   Even with all that evidence, we continue to put general relativity to the test. Any sign of a crack in Einstein's magnificent work would spark the development of a new theory of gravity, perhaps paving the way to uncovering the full quantum nature of that force. That's something we currently don't understand at all.

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-   In all regards, GR passes with flying colors; from sensitive satellites to gravitational lensing, from the orbits of stars around giant black holes to ripples of gravitational waves and the evolution of the universe itself, Einstein's legacy is likely to persist for quite some time.

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October 21, 2024      RELATIVITY  -  The Evidence for Einstein's Theory         4582

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--------------------- ---  Monday, October 21, 2024  ---------------------------------

 

 

 

 

 

           

 

 

- 4580 - LARGER GALAXY STRUCTURES?

 

-  4580  -  LARGER  GALAXY STRUCTURES?  -  The Milky Way might be part of an even larger structure than Laniakea.  If you want to pinpoint your place in the Universe, start with your cosmic address. You live on Earth->Solar System->Milky Way Galaxy->Local Cluster->Virgo Cluster->Virgo Supercluster->Laniakea.

-----------------------------------  4580  -    LARGER  GALAXY STRUCTURES?

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-   Thanks to new deep sky surveys, astronomers now think all above places are part of an even bigger cosmic structure in the “neighborhood” called the “Shapley Concentration”.

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-   Astronomers refer to the Shapley Concentration as a “basin of attraction”. That’s a region loaded with mass that acts as an “attractor”. It’s a region containing many clusters and groups of galaxies and comprises the greatest concentration of matter in the local Universe. All those galaxies, plus dark matter, lend their gravitational influence to the Concentration. There are many of these basins in the Universe, including Laniakea.

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-     Astronomers measured the motions of some 56,000 galaxies to understand these basins and their distribution in space.  Our universe is like a giant web, with galaxies lying along filaments and clustering at nodes where gravitational forces pull them together.   Just as water flows within watersheds, galaxies flow within cosmic basins of attraction. The discovery of these larger basins could fundamentally change our understanding of cosmic structure.

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-    “Redshift” surveys revealed a possible shift in the size and scale of our local galactic basin of attraction. We already know that we “live” in Laniakea, which is about 500 million light-years across. However, the motions of other clusters indicate there’s a larger “attractor” directing the cluster flow.

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-    The Cosmic Flows data suggest that we could be part of the “Shapley Concentration”, which could be 10 times the volume of Laniakea. It’s about half the volume of the largest structure in space, known as “the Great Wall”, which is a string of galaxies stretching across  1.4 billion light-years.

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-    The “2dF Galaxy Redshift Survey”  contains the structure known as the "Sloan Great Wall". The Shapley Concentration was first observed by astronomer Harlow Shapley in the 1930s as a “cloud” in the constellation Centaurus. This supercluster appears along the direction of motion of the Local Group of galaxies (where we live).

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-    Scientists speculated that this could be influencing our galaxy’s peculiar motion.  The Virgo Supercluster (and the Local Group and Milky Way Galaxy) appears to be moving toward the Shapley Concentration.

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-    Where do these basins of attraction come from? In one sense, they’re as old as the Universe and its cosmic web of matter. The seeds for the web and those basins of attraction were planted some 13.8 billion years ago.

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-    After the Big Bang, the infant Universe was in a hot dense state. As it expanded and cooled, the density of matter started to fluctuate. There were tiny differences in those density fluctuations. Think of them as the earliest “seeds” of galaxies, galaxy clusters, and even vaster structures that we see in today’s Universe.

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-   As astronomers survey the sky, they find evidence for all those different structures. Now, they have to explain them. The idea that the Shapley Concentration is the large basin that our Laniakea belongs to means that current cosmological models don’t quite explain its existence.

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-    Our cosmic surveys may not yet be large enough to map the full extent of these immense basins.   The main actor in all these galaxies, clusters, and superclusters, is gravity. The more mass, the more gravity influences motions and matter distribution.

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-     These basins of attraction exert a sort of “tug of war” on galaxies that lie between them. That influences their motions. In particular, redshift surveys will map the radial motion (along the line of sight), velocities (how fast they’re moving), and other related motions. By mapping the velocities of galaxies throughout our local Universe, they can define the region of space where each supercluster dominates.

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-   Astronomers aren’t mapping just the luminous material in galaxies. They also have to take into account the inferred existence of dark matter. There are other complications as well.   Not all galaxies are the same.   They differ in their shapes and matter density. Astronomers can get around this by measuring something called “galaxy peculiar velocity”. That’s the difference between its actual velocity and the expected “Hubble flow” velocity (which reflects gravitational interactions between galaxies).

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-    The results of these surveys should provide ever more precise 3D maps of these regions of space. That includes their structures as well as their motions and velocities. Those maps, in turn, should give greater insight into the distribution of all matter (including cold dark matter) throughout the Universe.

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October 19, 2024          LARGER  GALAXY STRUCTURES?                   4580

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

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

--------------------- ---  Sunday, October 20, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4579 - DARK MATTER MYSTERIES?

 

-  4579  -  DARK  MATTER  MYSTERIES?  -    Perhaps our theories of gravity are simply incorrect, and that the fundamental force works differently on large scales than we expect. Often known as "modified Newtonian dynamics," or MOND models, these suggestions that there is no dark matter and the ultrafast speeds at which stars and galaxies are seen to rotate around one another is a consequence of gravity behaving in surprising ways.

-------------------------------------------  4579  -  DARK  MATTER  MYSTERIES?

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-   In the 1930s, a Swiss astronomer named Fritz Zwicky noticed that galaxies in a distant cluster were orbiting one another much faster than they should have been given the amount of visible mass they had. He proposed than an unseen substance, which he called “dark matter”, might be tugging gravitationally on these galaxies.

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-   Since then, researchers have confirmed that this mysterious material can be found throughout the universe, and that it is six times more abundant than the normal matter that makes up ordinary things like stars and people.

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-     Originally, some scientists conjectured that the missing mass in the universe was made up of small faint stars and black holes, though detailed observations have not turned up nearly enough such objects to account for dark matter's influence.

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-    The current leading contender for dark matter's mantle is a hypothetical particle called a “Weakly Interacting Massive Particle”, or WIMP, which would behave sort of like a neutron except would be between 10 and 100 times heavier than a proton.

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-    If dark matter is made from WIMPs, they should be all around us, invisible and barely detectable. So why haven't we found any yet? While they wouldn't interact with ordinary matter very much, there is always some slight chance that a dark-matter particle could hit a normal particle like a proton or electron as it travels through space.

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-    Researchers have built experiment after experiment to study huge numbers of ordinary particles deep underground, where they are shielded from interfering radiation that could mimic a dark-matter-particle collision. The problem? After decades of searching, not one of these detectors has made a credible discovery.

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-    Earlier this year, the Chinese PandaX experiment reported the latest WIMP nondetection. It seems likely that dark-matter particles are much smaller than WIMPs, or lack the properties that would make them easy to detect.

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-    Ordinary matter is made up of everyday particles like protons and electrons, as well as a whole zoo of more exotic particles like neutrinos, muons and pions. So, some researchers have wondered if dark matter, which makes up 85 percent of the matter in the universe, might also be just as complicated.

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-   There is no good reason to assume that all the dark matter in the universe is built out of one type of particle.   Dark protons could combine with dark electrons to form dark atoms, producing configurations as diverse and interesting as those found in the visible world.

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-     Along with additional particles of dark matter, there is the possibility that dark matter experiences forces analogous to those felt by regular matter. Some researchers have searched for "dark photons," which would be like the photons exchanged between normal particles that give rise to the electromagnetic force, except they would be felt only by dark matter particles.

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-    Physicists in Italy are gearing up to smash a beam of electrons and their antiparticles, known as positrons, into a diamond.  If dark photons do exist, the electron-positron pairs could annihilate and produce one of the strange force-carrying particles, potentially opening a brand-new sector of the universe.

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-    Other dark-matter particles are starting to gain favor. One of the leading replacements is a hypothetical particle known as an “axion”, which would be extremely light, perhaps as little as 10 raised to the 31st power less massive than a proton.

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-    Axions are now being searched for in a few experiments. Recent computer simulations have raised the possibility that these axions could form star-like objects, which might produce detectable radiation that would be quite similar to mysterious phenomena known as “fast-radio bursts”.

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-    Astronomers discovered dark matter through its gravitational interactions with ordinary matter, suggesting that this is its main way of making its presence known in the universe. According to some theories, dark-matter particles should be their own antiparticles, meaning that two dark-matter particles would annihilate with one another when they meet.

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-    The “Alpha Magnetic Spectrometer” (AMS) experiment on the International Space Station has been searching for the telltale signs of this annihilation since 2011and has already detected hundreds of thousands of events. Scientists still aren't sure if these are coming from dark matter, and the signal has yet to help them pin down exactly what dark matter is.

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-    Because it so massively outweighs ordinary matter, dark matter is often said to be the controlling force that organizes large structures such as galaxies and galactic clusters. So, it was strange when, earlier this year, 2024, astronomers announced that they had found a galaxy named “NGC 1052-DF2” that seemed to contain hardly any dark matter at all. "Dark matter is apparently not a requirement for forming a galaxy”.

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-     A long-standing mystery in particle physics are the puzzling results of a European experiment known as DAMA/LIBRA. This detector located in an underground mine below the Gran Sasso mountain in Italy has been searching for a periodic oscillation in dark matter particles. This oscillation should arise as the Earth moves in its orbit around the sun while flying through the galactic stream of dark matter surrounding our solar system, sometimes called the “dark matter wind”. Since 1997, DAMA/LIBRA has claimed to see exactly this signal, though no other experiment has seen anything like this. 

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-   A signal from the beginning of time has led some physicists to suggest that dark matter might have an electrical charge. Radiation with a wavelength of 21 centimeters was emitted by stars in the universe's infancy, just 180 million years after the Big Bang. It was then absorbed by cold hydrogen that was around at the same time.

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-    Neutrons are regular matter particles with a limited lifetime. After around 14.5 minutes, a lone neutron unmoored from an atom will decay into a proton, an electron and a neutrino. But two different experimental setups give slightly different lifetimes for this decay, with the discrepancy between them about 9 seconds.

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-    Physicists suggested that if 1 percent of the time, some neutrons were decaying into dark-matter particles, it could account for this anomaly.   Astronomers monitored neutrons for a signal that could be dark matter but were unable to detect anything. They suggested that other decay scenarios might still be possible.    Given the difficulties that scientists have faced trying to detect and explain dark matter, a reasonable questioner might wonder if they're going about it all wrong.

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-    Dark matter is still an “unconfirmed model".  However, the latest evidence also suggests that dark matter is “real”.

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October 18, 2024            DARK  MA?TTER  MYSTERIES?                 4579

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--------  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”  -----------

--------------------- ---  Sunday, October 20, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4578 - JAMES WEBB - discoveries strange galaxies?

 

-  4578  -  JAMES  WEBB  -  discoveries strange galaxies?     James Webb Space Telescope results have revealed that there may not be a Hubble tension after all. But contradictions within the findings point to a deeper mystery.   For years, astronomers have found that the universe appears to be expanding at different speeds depending on where they look, a conundrum they call the “Hubble tension”.\

----------------------------------  4578  -   JAMES  WEBB  -  discoveries strange galaxies?

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-   When JWST came online in 2022, one team of researchers used the space telescope's unprecedented accuracy to confirm the tension exists. But according to the new results from a different team of scientists, the Hubble tension may arise from measurement error and be an illusion after all. Yet even these results are not definitive.

-

-    Currently, there are two gold-standard methods for figuring out the Hubble constant, a value that describes the expansion rate of the universe. The first involves poring over tiny fluctuations in the cosmic microwave background.  The CMB is an ancient relic of the universe's first light produced just 380,000 years after the Big Bang.

-

-    After mapping out this microwave hiss using the European Space Agency's Planck satellite, cosmologists inferred a Hubble constant of roughly 46,200 mph per million light-years, or around 67 kilometers per second per megaparsec (km/s/Mpc). This, alongside other measurements of the early universe, aligned with theoretical predictions.

-

-    The second method operates at closer distances and in the universe's later life using pulsating stars called Cepheid variables. Cepheid stars are slowly dying, and their outer layers of helium gas grow and shrink as they absorb and release the star's radiation, making them periodically flicker like distant signal lamps.

-

-   As Cepheids get brighter, they pulsate more slowly, enabling astronomers to measure the stars' intrinsic brightness. By comparing this brightness to their observed brightness, astronomers can chain Cepheids into a "cosmic distance ladder" to peer ever deeper into the universe's past.

-

-   The Hubble constant measured using the Hubble Space Telescope and JWST found a puzzlingly high value of 73.2 km/s/Mpc. Hence the tension, a significant discrepancy between methods measuring the expansion rate in the early universe and those in the more modern one.

-

-  It was suggested that dust, gas and other stars could be throwing off the brightness measurements of the Cepheids, creating the appearance of a discrepancy where there isn‘t one at all.

-

-   In this study, to tease out a possible systematic error in Cepheid crowding, astronomer trained JWST on 11 nearby galaxies containing Type Ia supernovae, measuring their distances and anchoring them to three independent distance ladders with intrinsic brightnesses in similar regions of the sky: the Cepheids; and two other standard candle red giant stars known as "tip-of-the-red-giant-branch" (TRGB) stars and J-region asymptotic giant branch (JAGB) stars.

-

-    The TRGB and JAGB stars gave Hubble constant results of 69.85 km/s/Mpc and 67.96 km/s/Mpc, respectively. But the Cepheids returned 72.04 km/s/Mpc, replicating the Hubble tension.

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-     JWST confirms the earliest galaxy in the universe is bursting with way more stars than we thought possible.    Named JADES-GS-z14-0, the galaxy formed at least 290 million years after the Big Bang, and contains stars that have been bursting into life since an estimated 200 million years after our universe began.

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-   These mysterious origins and rapid development of the stars has opened up some fundamental questions about how our universe came to be.   The discovery by JWST of an abundance of luminous galaxies in the very early Universe suggests that galaxies developed rapidly, in apparent tension with many standard models.

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-   Astronomers aren't certain when the very first globules of stars began to clump into the galaxies we see today, but cosmologists previously estimated that the process began slowly within the first few hundred million years after the Big Bang.

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-    Current theories suggest that halos of dark matter (a mysterious and invisible substance believed to make up 85% of the total matter in the universe) combined with gas to form the first seedlings of galaxies. One billion to 2 billion years into the universe's life, these early protogalaxies reached adolescence, forming into dwarf galaxies that began devouring one another to grow into ones like our own.

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-   In February 2023, a group of astronomers analyzing data from the telescope discovered a group of six gargantuan galaxies, aged between 500 to 700 million years after the Big Bang, that were so massive they were in tension with 99% of cosmological models.

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-   The light from JADES-GS-z14-0 is similarly puzzling.   The light detected by NIRSpec finds its origins in an enormous halo of young stars surrounding the galaxy's core, which have been burning for at least 90 million years before the point of its observation. The galaxy is also crammed with unusually high quantities of dust and oxygen, which suggests its history of star birth and death may be even longer.

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-    This finding shows that ultra-bright galaxies in the early universe are not just the product of active black holes greedily gobbling up matter, as is often assumed to be the case. The new observations show that runaway star formation is also a viable explanation for the surprising brightness of these ancient galaxies.

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-   So how did galaxies like JADES-GS-z14-0 produce so many stars, so quickly? Answers to this cosmic mystery remain elusive, but it's unlikely they will break our current understanding of cosmology. Instead, astronomers are toying with explanations that include the earlier-than-anticipated appearance of giant black holes; supernova feedback; or even dark energy to understand why these ancient stars were able to form so rapidly.

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October 17, 2024             JAMES  WEBB  -  discoveries strange galaxies?                4578

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

--------  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”  -----------

--------------------- ---  Thursday, October 17, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4576 - HUBBLE TENSION - how fast is Universe expanding?

 

-   4576  -   HUBBLE  TENSION  -  how fast is Universe expanding?    The “Hubble Tension' is the dilemma that the expansion rate for the Universe seems to be different depending on what direction you look or how you measure it.  The James Webb Space Telescope results have revealed that there may not be a Hubble tension after all. But contradictions within the findings point to a deeper mystery.

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------------------=-=----------  4576  -   HUBBLE  TENSION  -  how fast is Universe expanding? 

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-    New measurements taken with JWST have deepened the scientific controversy of the “Hubble tension”, suggesting it may not exist at all.   For years, astronomers have found that the universe appears to be expanding at different speeds depending on where they look, a conundrum they call the “Hubble tension”. Some of the measurements agree with our best current understanding of the universe, while others threaten to break it.

-

-   When JWST came online in 2022, one team of researchers used the space telescope's unprecedented accuracy to confirm the tension exists. But according to the new results from a different team of scientists, the Hubble tension may arise from measurement error and be an illusion after all. Yet even these results are not definitive.

-

-    Currently, there are two gold-standard methods for figuring out the “Hubble constant of Universe expansion rate” a value that describes this expansion rate. The first involves poring over tiny fluctuations in the cosmic microwave background which is an ancient relic of the universe's first light produced just 380,000 years after the Big Bang.

-

-   After mapping out this microwave hiss using the European Space Agency's Planck satellite, cosmologists inferred a Hubble constant of  “46,200 mph per million light-years”, or around “67 kilometers per second per megaparsec (km/s/Mpc)”. This, alongside other measurements of the early universe, aligned with many theoretical predictions.

-

-   The second method operates at closer distances and in the universe's later life using pulsating stars called “Cepheid variables”. Cepheid stars are slowly dying, and their outer layers of helium gas grow and shrink as they absorb and release the star's radiation, making them periodically flicker like distant signal lamps.

-

-  As Cepheids get brighter, they pulsate more slowly, enabling astronomers to measure the stars' intrinsic brightness. By comparing this brightness to their observed brightness, astronomers can chain Cepheids into a "cosmic distance ladder" to peer ever deeper into the universe's past.

-

-   Astronomer measured the Hubble constant using the Hubble Space Telescope and JWST, they found a puzzlingly high value of 73.2 km/s/Mpc. Hence the tension, a significant discrepancy between methods measuring the expansion rate in the early universe and those in the more modern one.

-

-   But some previously suggested that dust, gas and other stars could be throwing off the brightness measurements of the Cepheids, creating the appearance of a discrepancy where there isn‘t one at all.

-

-   In the new study, to tease out a possible systematic error in Cepheid crowding, they trained JWST on 11 nearby galaxies containing Type Ia supernovae, measuring their distances and anchoring them to three independent distance ladders with intrinsic brightnesses in similar regions of the sky: the Cepheids; and two other standard candle red giant stars known as "tip-of-the-red-giant-branch" (TRGB) stars and J-region asymptotic giant branch (JAGB) stars.

-

-    Their results were puzzling. The TRGB and JAGB stars gave Hubble constant results of 69.85 km/s/Mpc and 67.96 km/s/Mpc, respectively. But the Cepheids returned 72.04 km/s/Mpc, replicating the Hubble tension.

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-   To make a measurement of Cepheid stars you get the star colors wrong, you get the dust correction wrong, you get the metallicity correction wrong. And, you get a different expansion rate.

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-   Astronomers believe the answer is to make even more measurements, potentially some with an additional type of star. This work to be completed in the next two years.   JWST is a marvelous machine, and it's exactly what we need to get at some of these kinds of issues. It's a good time to be working on this.

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October 15, 2024        HUBBLE  TENSION  -  how fast is Universe expanding?          4576

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

--------  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”  -----------

--------------------- ---  Tuesday, October 15, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4577 - OLDEST GALAXIES - too old to make sense?

 

-  4577  -   OLDEST  GALAXIES  -  too old to make sense?  -  The  James Webb Space Telescope found "tiny red dots" in the early universe representing overgrown supermassive black holes and stars that are impossibly old for the infant universe.

----------------------------  4577  -   OLDEST  GALAXIES  -  too old to make sense?

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-    These “odd red bodies” hide stars that models suggest are "too old" to have lived during early cosmic times and black holes that measure up to thousands of times larger than the supermassive black hole at the heart of the Milky Way. Scientists believe these objects must have been born in a way unique to the early universe by a method that seems to have ceased after around 1 billion years of its existence.

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-   The three little red dots are seen as they were when the universe was between 600 million and 800 million years old. Though that may seem like a tremendously long time after the Big Bang, the fact that the universe is 13.8 billion years old means it was no more than 5% of its current age when these objects existed.

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-    This is very confusing.  You can make this uncomfortably fit in our current model of the universe, but only if we evoke some exotic, insanely rapid formation at the beginning of time.

The researchers studied the intensity of different wavelengths of light coming from the little red dots. This revealed signs that the stars are hundreds of millions of years old.  This is far older than is expected for stars at this early stage of the universe.

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-   The researchers also saw traces of supermassive black holes within the little red dots' regions with masses equivalent to millions, sometimes even billions, of suns. These black holes are between 100 and 1,000 times as massive as Sagittarius A* (Sgr A*), the supermassive black hole at the heart of the Milky Way that sits just 26,000 light-years from Earth.

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-   Both of these discoveries are not expected under current models of cosmic evolution, galaxy growth, or supermassive black hole formation. All of these theories suggest galaxies and supermassive black holes grow in lockstep, but this growth takes billions of years.

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-    They have also confirmed that these galaxies appear to be packed with ancient stars, hundreds of millions of years old, in a universe that is only 600 million to 800 million years old.   These objects hold the record for the earliest signatures of old starlight.   It was totally unexpected to find old stars in a very young universe. These luminous objects do not quite fit comfortably into commology theories.

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-   They first spotted the little red dots while using the JWST back in July, 2024. At the time, the researchers immediately suspected the objects were actually galaxies that existed roughly     13.5 billion years ago.  Deeper investigation of these objects' light spectra confirmed these as galaxies that lived during the very dawn of time and also revealed that "overgrown" supermassive black holes and impossibly "old" stars were powering the red dots' impressive light output.

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-   They are not certain how much of the light from the little red dots comes from each of these sources. That means these galaxies are either unexpectedly old and more massive than the Milky Way, having formed far earlier than models predict, or have normal amounts of mass yet overly massive black holes somehow.  These are voids that are vastly more massive than a similar galaxy would have during the current epoch of the universe.

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-    Distinguishing between light from material falling into a black hole and light emitted from stars in these tiny, distant objects is challenging.    That inability to tell the difference in the current dataset leaves ample room for interpretation of these intriguing object.

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-  All black holes have light-trapping boundaries called "event horizons,", however much light they contribute to the little red dots,  must come from the material that surrounds them rather than from within.

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-    The tremendous gravitational influence of the black holes generates turbulent conditions in this material, which also feeds the black hole over time, heating it and causing it to glow brightly. Regions powered by supermassive black holes in this way are called "quasars," and the regions of their galaxies they sit in are known as "active galactic nuclei (AGNs).

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-   These newly found, "red dot" black hole regions could be different from other quasars, even those the JWST has already seen in the early universe.   The red dot black holes seem to produce far more ultraviolet light than expected. Still, the most shocking thing about these supermassive black holes remains just how massive they seem.

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-   Normally, supermassive black holes are paired with galaxies.   They grow up together and go through all their major life experiences together. But here, we have a fully formed adult black hole living inside of what should be a baby galaxy.

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-    That doesn't really make sense because these things should grow together, or at least that’s what we thought.  The red dot galaxies themselves are also surprising. They seem to be much smaller than other galaxies despite having almost as many stars. That means the red dot galaxies seem to consist of between 10 billion and 1 trillion stars crammed into a galaxy a few hundred light-years across with a volume 1,000 times smaller than the Milky Way.

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-   If the Milky Way were reduced to the size of one of these red dot galaxies, then the closest star to the sun (Proxima Centauri, which is 4.2 light-years away) would be within the solar system. Additionally, the distance between the Earth and the Milky Way's supermassive black hole, Sgr A*, would be reduced from 26,000 light-years to just 26 light-years. That would see it and its surroundings appearing in the night sky over Earth.

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-   These early galaxies would be so dense with stars.  These stars that must have formed in a way we've never seen, under conditions we would never expect during a period in which we’d never expect to see them.    The universe stopped making objects like these after just a couple of billion years. They are unique to the early universe.

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-   Astronomers will be obtaining deeper spectra by pointing the JWST at the red objects for prolonged periods of time to obtain emission spectra of light associated with various elements. This could help unravel the contributions of ancient stars and supermassive black holes in the galaxies.

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October 15, 2024          OLDEST  GALAXIES  -  too old to make sense?                   4577

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--------  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”  -----------

--------------------- ---  Tuesday, October 15, 2024  ---------------------------------

 

 

 

 

 

           

 

 

4575 - FARTHEST GALAXIES - earliest galaxies?

 

-  4575  -  FARTHEST GALAXIES  -  earliest galaxies?  -   James Webb Space Telescope found "tiny red dots" in the early universe representing overgrown supermassive black holes and stars that are impossibly old for the infant universe.  These odd red bodies hide stars that models suggest are "too old" to have lived during early cosmic times and black holes that measure up to thousands of times larger than the supermassive black hole at the heart of the Milky Way.

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----------------------------------------------  4575  -    FARTHEST GALAXIES  -  earliest galaxies?

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-    Scientists believe these “tiny red dots” must have been born in a way unique to the early universe by a method that seems to have ceased after around 1 billion years of its existence.  The three little red dots are seen as they were when the universe was between 600 million and 800 million years old.

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-    Though that may seem like a tremendously long time after the Big Bang, the fact that the universe is 13.8 billion years old means it was no more than 5% of its current age when these objects existed.

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-  Scientists from Penn State University saw these mysterious crimson cosmic oddities when investigating the early universe with the JWST's Near Infrared Spectrograph (NIRSpec) instrument as part of the RUBIES survey. 

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-   What's behind the dots?  The researchers studied the intensity of different wavelengths of light coming from the little red dots. This revealed signs that the stars are hundreds of millions of years old.  This is far older than is expected for stars at this early stage of the universe.

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-   The researchers also saw traces of supermassive black holes within the little red dots' regions with masses equivalent to millions, sometimes even billions, of suns. These black holes are between 100 and 1,000 times as massive as Sagittarius A* (Sgr A*), the supermassive black hole at the heart of the Milky Way that sits just 26,000 light-years from Earth.

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-    Both of these discoveries are not expected under current models of cosmic evolution, galaxy growth, or supermassive black hole formation. All of these theories suggest galaxies and supermassive black holes grow in lockstep, but,  this growth takes billions of years, not millions of years.  That's a difference of a 1000 times???

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-   These regions appear to be packed with ancient stars, hundreds of millions of years old, in a universe that is only 600 million to 800 million years old. Remarkably, these objects hold the record for the earliest signatures of old starlight.  It was totally unexpected to find old stars in a very young universe.

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-    They first spotted the little red dots while using the JWST back in July. At the time, the researchers immediately suspected the objects were actually galaxies that existed roughly 13.5 billion years ago.

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-    Deeper investigation of these objects' light spectra confirmed these as galaxies that lived during the very dawn of time and also revealed that "overgrown" supermassive black holes and impossibly "old" stars were powering the red dots' impressive light output.

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-    These galaxies are either unexpectedly old and more massive than the Milky Way, having formed far earlier than models predict, or have normal amounts of mass yet overly massive black holes somehow.

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-    Distinguishing between light from material falling into a black hole and light emitted from stars in these tiny, distant objects is challenging.    Of course, all black holes have light-trapping boundaries called "event horizons," meaning that, however much light they contribute to the little red dots, it must come from the material that surrounds them rather than from within.

-

-    The tremendous gravitational influence of the black holes generates turbulent conditions in this material, which also feeds the black hole over time, heating it and causing it to glow brightly. Regions powered by supermassive black holes in this way are called "quasars," and the regions of their galaxies they sit in are known as "active galactic nuclei (AGNs)."

-

-   These newly found, "red dot" black hole regions could be different from other quasars, even those the JWST has already seen in the early universe.   The red dot black holes seem to produce far more ultraviolet light than expected. Still, the most shocking thing about these supermassive black holes remains just how massive they seem.

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-    The ultraviolet light has the highest energy.  By the time that light reasches us it lost energy and is in the red end of the light spectrum.

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-   Normally, supermassive black holes are paired with galaxies.    They grow up together and go through all their major life experiences together. But here, are fully formed adult black hole living inside of what should be a baby galaxy.   That doesn't really make sense because these things should grow together, or at least that’s what we thought.

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-    Using both the Gemini North telescope and the Subaru Telescope, a team of astronomers have discovered a pair of merging quasars seen only 900 million years after the Big Bang. Not only is this the most distant pair of merging quasars ever found, but also the first confirmed pair found in the period of the universe known as “cosmic dawn”.

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-    The red dot galaxies themselves are also surprising. They seem to be much smaller than other galaxies despite having almost as many stars. That means the red dot galaxies seem to consist of between 10 billion and 1 trillion stars crammed into a galaxy a few hundred light-years across with a volume 1,000 times smaller than the Milky Way.

-

-   To put that into context, if the Milky Way were reduced to the size of one of these red dot galaxies, then the closest star to the sun (Proxima Centauri, which is 4.2 light-years away) would be within the solar system. Additionally, the distance between the Earth and the Milky Way's supermassive black hole, Sgr A*, would be reduced from 26,000 light-years to just 26 light-years. That would see it and its surroundings appearing in the night sky over Earth.

-

-    These early galaxies would be dense with stars.   Stars must have formed in a way we've never seen, under conditions we would never expect during a period in which we’d never expect to see them.   And, the universe stopped making objects like these after just a couple of billion years. They are unique to the early universe.

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-    The team intends to follow up on its findings with more observations of these confusing little red dots to understand the dots' mysteries better. This will include obtaining deeper spectra by pointing the JWST at the red objects for prolonged periods of time to obtain emission spectra of light associated with various elements. This could help unravel the contributions of ancient stars and supermassive black holes in the galaxies.

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-    There's another way that we could have a breakthrough, and that's just having the right idea. We have all these puzzle pieces, and they only fit if we ignore the fact that some of them are breaking. This problem is amenable to a stroke of genius that has so far eluded us, all of our collaborators, and the entire scientific community.

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October 12, 2024           FARTHEST GALAXIES  -  earliest galaxies?                 4575

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

--------  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”  -----------

--------------------- ---  Sunday, October 13, 2024  ---------------------------------