JimsAstronomy: November 2024

Wednesday, November 13, 2024

4607 - GEOMAGNETIC STORM - are they harmful?

- 4607 - GEOMAGNETIC STORM - are they harmful? A geomagnetic storm lit up the night sky in parts of the U.S. during the first weekend in October. The storm had originated from a solar flare that erupted from “sunspot 3842” on October 3, 2024.

---------------------------------- 4607 - GEOMAGNETIC STORM - are they harmful?

- This was the strongest Earth-facing solar flare recorded by “Sansa” in the past seven years and that the eruption briefly affected high-frequency radio communications, resulting in a total radio blackout over the African region which lasted for up to 20 minutes.

- A geomagnetic storm is a disturbance in Earth's magnetic field caused by solar activity. There's a reaction called nuclear fusion that occurs continuously deep within the sun's core. This generates massive amounts of energy. Some of the energy is released as light (sunlight), some as radiation (solar flares), and some as charged particles.

- The sun also continuously emits a stream of charged particles known as the solar wind. Occasionally, the sun releases larger bursts of energy, called “coronal mass ejections”. It sends clouds of these charged particles, or plasma, hurtling through space. This "burp" is the cloud of plasma which then travels through space. These emissions don't always hit us. But when they do, they collide with Earth's magnetic field, disrupt it, and lead to a geomagnetic storm.

- Earth's magnetic field is an invisible force that surrounds our planet, acting like a giant magnet with a north and south pole. It helps protect us from harmful solar radiation by deflecting charged particles from the sun.

- The solar flare from “3842” emitted both X-flares (radiation) and a coronal mass ejection. X-flares are radiation; they travel at almost the speed of light and reach Earth within minutes. That's what caused the brief communications disruption Sansa mentioned on 3 October. But the coronal mass ejection takes much longer to reach us.

- Geomagnetic storms occur fairly often. Minor ones happen multiple times per year. The severity of a storm depends on how strong the solar event was that caused it. Larger, more intense storms are less common but can happen every few years.

- Solar events are closely tied to the sun's 11-year solar cycle, which has periods of high and low activity. During the peak of the cycle, called solar maximum, more sunspots and solar flares occur, increasing the likelihood of solar storms. We are now heading towards the peak of Solar Cycle 25, which will be in July 2025. Solar maxima usually last between two and three years.

- Are these storms dangerous? What damage can they cause? Geomagnetic storms are not typically harmful to humans directly, but they can pose risks to modern technology and infrastructure. One of the most notable dangers is to power grids. Powerful storms can induce electric currents in power lines, potentially overloading transformers and causing blackouts, as happened in Quebec, Canada, in 1989.

- Satellites in space are also vulnerable. A strong storm can damage electronics onboard, disrupt communication signals, and shorten the lifespan of the satellites themselves.

- In aviation, geomagnetic storms can disrupt radio communication and GPS signals, which are vital for aircraft navigation. This is especially important for flights that pass near the polar regions, where the effects of geomagnetic storms are more pronounced. Astronauts and spacecraft are also at risk. The extra radiation can be dangerous for equipment and human health.

- Auroras are a visually stunning aspect of geomagnetic storms. These colorful displays in the night sky occur when charged particles from the sun get captured in Earth's magnetic field lines, and funnel down towards the poles. Here they interact with Earth's atmosphere, releasing energy that produces shimmering lights.

- Auroras can be seen at both the north and south poles, aptly named the northern and southern lights. If storms are big enough, it's possible to see them in regions much further away from the poles. This happened in South Africa on 11 May 2024.

- Studying geomagnetic storms provides valuable insights into space weather. By understanding how the sun's activity affects Earth, scientists can better predict future storms and work to protect the technologies we rely on. The study of geomagnetic storms also contributes to our understanding of the sun and space in general.

- Geomagnetic storms are monitored using various instruments on Earth and in space. On Earth, magnetometers measure changes in the magnetic field, allowing scientists to track disturbances as they happen.

- “Sansa” operates a dense network of Global Navigation Satellite System receivers in Africa, and magnetometer stations in various parts of southern Africa, for this reason. The agency is currently setting up a magnetometer station in Ethiopia, too. This will improve our ability to monitor geomagnetic storms.

- In space, satellites equipped with sensors monitor the sun's activity and detect solar flares or coronal mass ejections before they reach Earth. This data feeds into prediction models used in space weather centers across the globe.

- Once a storm is detected, agencies like Sansa issue alerts and forecasts. These warnings help industries such as power grid operators, satellite companies and aviation authorities to prepare for a storm.

- For example, power companies can temporarily shut down or reconfigure parts of the grid to avoid overloading during a storm. Satellite operators can place their spacecraft into safer operating modes, such as switching off electronic components, and airlines can reroute flights away from high-risk areas.

- Monitoring alone can't prevent all the damage caused by geomagnetic storms. But it can greatly reduce the risks. Thanks to early warning systems, we can protect crucial infrastructure and minimize the effect these storms have on our daily lives.

November 12, 2024 GEOMAGNETIC STORM - are they harmful? 4607

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--------------------- --- Wednesday, November 13, 2024 ---------------------------------

4606 - ANCIENT MAN - where did they originate?

- 4606 - ANCIENT MAN - where did they originate? - An 86,000-year-old human bone found in Laos cave hints at 'failed population' from prehistory. The discovery of a skull and shin bone fragment in a cave in Laos pushes back the earliest known date of Homo sapiens in Southeast Asia. Researchers at Tam Pà Ling cave in Laos have found a fragment of a human shinbone that is up to 86,000 years old.

-------------------------------- 4606 - ANCIENT MAN - where did they originate?

- The finding comes from the cave of Tam Pà Ling, or “Cave of the Monkeys”, which sits at around 3,840 feet above sea level on a mountain in northern Laos. Human bone fragments previously found in the cave were 70,000 years old, making them some of the earliest evidence of humans in this area of the world.

- The bones were fragments of the front of a skull and a shin bone and were likely washed into the Tam Pà Ling cave during a monsoon. Even though the bones were fractured and incomplete, the researchers were able to compare their dimensions and shape with other bones from early humans, finding that they most closely matched Homo sapiens rather than other archaic humans, such as Homo erectus, Neandertals or Denisovans.

- The researchers used “luminescence dating” of nearby sediments and “uranium-series

dating “of mammalian teeth from the same layers to produce an age range for the human remains. Luminescence dating is a technique that measures the last time crystalline materials, such as stones, were exposed to sunlight or heat, while U-series dating is a radiometric technique that, similar to carbon-14 dating, measures the decay of uranium over time into thorium, radium and lead.

- The skull, they estimated, was up to 73,000 years old, and the shin bone dates back as far as 86,000 years ago. This early date is a remarkable finding, particularly because researchers have long debated the timing of Homo sapiens' arrival in Asia.

- Little to no anthropological research was done in Laos since the second world war. Debates about human colonization of Southeast Asia have taken place for decades as researchers have attempted to understand how and when humans crossed straits and seas to eventually end up in Australia. Mainland southeast Asia really sits at the crossroads of East Asia and island SE Asia/Australia.

- The team used luminescence dating of nearby sediments and uranium-series dating of mammalian teeth from the same cave layer to date the human fossils. While the genetic and stone tool evidence amassed to date strongly supports a single, rapid dispersal of Homo sapiens from Africa some time after 60,000 years ago, studies such as this one are producing evidence for earlier migrations, many of which may have been dead ends.

- Perhaps this was a group that dispersed to Southeast Asia and died out before they were able to contribute genes to today's human gene pool. No stone tools or other clues about these humans' lifestyles have been found in Tam Pà Ling. But archaeologists working on the prehistory of Asia have long suspected that, even before 65,000 years ago, ancient humans were capable of reaching islands and making sea crossings to populate seemingly remote parts of the world.

- From when our ancient relatives began walking on two feet to the first known medical amputation on Homo sapiens, here's what we learned about our human ancestors. Humans are exceptionally diverse, but we all have something in common: We're Homo sapiens, and we share a common ancestor. But the story of how we arose, spread around the globe and acted along the way is still emerging as scientists find new clues.

- The discovery of a 1.5 million-year-old vertebra from Israel hints that early humans migrated out of Africa not in one but multiple waves. It's unknown which human species the bone belongs to. Although there is just one human species today, there used to be multiple species in the genus Homo.

- Previously, researchers found evidence that a now-extinct human species left Africa for Eurasia at least 1.8 million years ago, and there's evidence that modern humans left Africa as early as 270,000 years ago. Now, the discovery of this vertebra (the oldest human bone ever found in Israel), reveals that humans likely left the African continent multiple times.

- Doing your own family tree is hard enough; now, researchers have attempted to do a family tree for all of humanity to see how everyone is related. In their investigation, the scientists looked at thousands of genome sequences from 215 populations from around the globe including from ancient and modern humans, as well as our ancient human relatives.

- A computer algorithm looked at genetic variations among genomes, enabling the team to see who was descended from and related to whom. After approximating where these ancestors lived, the researchers created a map for this gargantuan family tree. As one might expect, it all goes back to Africa.

- Bipedalism was common among the earliest known species of humankind, not only on the ground but also in trees. It coexisted with other types of movement in a tree environment, including quadrupedal (four-legged) movement using firm hand grips, clearly differing from that of gorillas and chimpanzees, which use the back of their phalanges for support ("knuckle walking").

- Walking on our own two feet is quite a feat, one that was pulled off by our ancestors as far back as 7 million years ago. The discovery was made when researchers studied a thigh bone and a pair of forearm bones from the 7 million-year-old Sahelanthropus tchadensis, which may be the oldest-known hominin, a relative of humans dating from the period after our ancestors split off from those of modern apes. It appears that S. tchadensis, who was found in Chad, both walked on two feet and also climbed trees.

- Oldest-known human relative in Europe is a 1.4 million-year-old jawbone was discovered in Spain. It may belong to the oldest-known human relative in Europe. The upper jawbone has features that showcase the evolutionary pattern of the human face, suggesting that it's closer to modern humans than it is to ape-like primates.

- It's possible that this jawbone belongs to Homo antecessor, whose position in the human family tree is controversial but may be a cousin of modern humans and Neanderthals (Homo neanderthalensis). Until this finding, the oldest-known human relative in Europe dated to 1.2 million years ago.

- Four different Australopithecus crania that were found in the Sterkfontein caves, South Africa. The Sterkfontein cave fossils was dated to 3.4 to 3.6 million years ago, far older than previously thought. The new date overturns the long-held belief that South African Australopithecus is a younger offshoot of East African Australopithecus afarensis.

- A new analysis of old, human-like bones revealed they may be more than 1 million years older than previously thought. The new date range, 3.4 million to 3.7 million years old, of these Australopithecus bones from Sterkfontein, South Africa, improves the odds that this species gave rise to humans.

- Sterkfontein is known for its “Australopithecus africanus” remains, but it's unclear if the studied bones belong to this species. If true, the finding could rewrite our understanding of how humans arose: The fossils would predate the iconic "Lucy" fossil, a 3.2 million-year-old Australopithecus afarensis in East Africa whose species was a prime contender for being our direct ancestor.

- Researchers in Laos uncovered an ancient molar that may have belonged to a Denisovan girl who lived up to 164,000 years ago. Not much is known about the Denisovans, but along with Neanderthals, they're the closest extinct relatives of modern humans. Precious few fossils exist from these humans, who are named after Denisova Cave in southern Siberia where their first-known remains were found. Over the years, their bones have also been found in China. Now, the discovery of a 164,000-year-old tooth from Laos reveals that the Denisovans also lived in Southeast Asia at low altitudes where it was warm and humid.

- The oldest medical amputation on record is prehistoric, dating to a Stone Age patient who lost a leg in Borneo 31,000 years ago. A skilled surgeon cut off a child's leg, whose stump showed signs of healing. That child hunter-gatherer went on to live for another six to nine years after the surgery, according to an analysis of the individual's tooth enamel. Previously, the oldest medical amputation on record dated to 7,000 years ago.

- A massive icy barrier that stood up to 300 stories tall may have blocked the way of the people who left Eurasia to become the first Americans. The existence of this frigid obstacle suggests that these people didn't cross the Bering land bridge from Asia to America on foot, but rather sailed on boats along the coast.

- Researchers came to this conclusion after analyzing 64 geological samples from six locations across the ancient bridge area. They found that the ice-free corridor didn't completely open until about 13,800 years ago, a confusing date given that other evidence suggests the first Americans arrived much earlier and that the Clovis culture found in New Mexico was already established at that time.

- Little kids today love running around and splashing in muddy puddles, and children from the last ice age were no different. Researchers found about 30 footprints from young children on top of track marks left by a giant sloth, one of the big creatures that once lived in the Americas. These 11,000-year-old prints, found in what is now New Mexico, suggest that the sloth's prints had become muddy, creating a prime spot for jumping.

- Thousands of years ago, ancient humans and animals left their footprints on a coastal stretch in England that researchers are calling a superhighway. Some of the tracks are about 8,500 years old, just a few thousand years after the last ice age ended.

- In addition to humans, researchers found the tracks of aurochs (an extinct ox species), red deer, wild boars, wolves, lynx and cranes. Based on the configuration of some of the human footprints, it's possible that these ancient people were hunting the species of animals whose prints are also preserved.

November 12, 2024 ANCIENT MAN - where did they originate? 4606

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--------------------- --- Wednesday, November 13, 2024 ---------------------------------

Monday, November 11, 2024

4605 - KILONOVA - when stars collide?

- 4605 - KILONOVA - when stars collide? - Astronomers have witnessed the titanic collision between two neutron stars that resulted in the birth of the smallest black hole ever seen and forged precious metals like gold, silver, and uranium. For the first time, we see the creation of atoms; we can measure the temperature of the matter and see the microphysics in this remote explosion.

--------------------------------------------- 4605 - KILONOVA - when stars collide?

- This violent and powerful collision occurred 130 million light-years away from us in the galaxy “NGC 4993”. It will hopefully paint a picture of the "past, present, and future" of the mergers of these dense dead stars. This could reveal the origins of elements heavier than iron, which can't be forged in even the most massive stars.

- The collision and merger of the neutron stars results in a powerful blast of light called a "kilonova." As the wreckage of this event expands at nearly the speed of light, the kilonova illuminates its surroundings with light as bright as hundreds of millions of suns.

- We can now see the moment where atomic nuclei and electrons are uniting in the afterglow. For the first time, we see the creation of atoms, we can measure the temperature of the matter, and we can see the microphysics in this remote explosion. We see before, during, and after the moment of birth of the atoms.

- The gold in your jewelry came from the universe's most violents events. Neutron stars are born when stars at least 8 times as massive as the sun exhaust their fuel for nuclear fusion and can no longer support themselves against their own gravity. They collapse and explode.

- The outer layers of these stars are blasted away in supernova explosions, leaving a stellar remnant with a mass equal to between 1 and 2 suns crushed into a diameter of around 12 miles.

The collapse of the core forces electrons and protons together, creating a sea of particles called neutrons. This material is so dense that a mere sugar cube's worth of neutron star matter would weigh 1 billion tons if brought to Earth. That's about the same as cramming 150,000,000 elephants into the same space that a sugar cube occupies.

- It is probably no surprise that this extreme and exotic matter plays a key role in creating elements heavier than iron.

- Neutron stars don't always live in isolation. Some of these dead stars occupy binary systems along with a companion living star. In rare instances, this companion star is also massive enough to create a neutron star, and it isn't "kicked away" by the supernova explosion that creates the first neutron star.

- The result is a system with two neutron stars orbiting each other. These objects are so dense that as they swirl around each other, they generate ripples in spacetime (the four-dimensional unification of space and time) called “gravitational waves” that ripple through space, carrying away angular momentum.

- As the system loses angular momentum, the orbit of the neutron stars tightens, meaning that the neutron stars move closer to each other. This results in gravitational waves rippling away faster and faster, carrying away more and more angular momentum.

- This situation ends when neutron stars are close enough for their immense gravity to take over and drag these extremely dense dead stars together to collide and merge. This collision sprays out neutron-rich matter with temperatures of many billions of degrees, thousands of times hotter than the sun. These temperatures are so hot that they are similar to those of the rapidly inflating universe just one second after the Big Bang.

- Ejected particles like electrons and neutrons dance around the body, the colliding neutron stars, which rapidly collapse to form a “black hole” in a fog of plasma that cools over the next few days.

- Atoms in this cooling cloud of plasma quickly grab free neutrons the rapid neutron capture process (r-process) and also ensnare free electrons. This creates very heavy but unstable particles that rapidly decay. This decay releases the light that astronomers see as kilonovas, but it also creates lighter elements that are still heavier than iron, like gold, silver and uranium.

- This team saw the afterglow of particles being snatched to forge heavy elements like Strontium and Yttrium, reasoning that other heavy elements were undoubtedly created in the aftermath of this neutron star collision.

- The matter expands so fast and gains in size so rapidly, to the extent where it takes hours for the light to travel across the explosion. This is why, just by observing the remote end of the fireball, we can see further back in the history of the explosion. Closer to us, the electrons have hooked to atomic nuclei, but on the other side, on the far side of the newborn black hole, the 'present' is still just the future. Think about that!

- The team's results wouldn't have been possible without the collaboration of telescopes across the globe and beyond. This astrophysical explosion develops dramatically hour by hour, so no single telescope can follow its entire story. The viewing angle of the individual telescopes to the event is blocked by the rotation of the Earth. But by combining the existing measurements from Australia, South Africa, and the Hubble Space Telescope, we can follow its development in great detail.

November 11, 2024 KILONOVA - when stars collide? 4605

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--------------------- --- Monday, November 11, 2024 ---------------------------------

4604 - EINSTEIN RING - could explain dark matter?

- 4604 - EINSTEIN RING - could explain dark matter? - The 'Einstein ring' suggests that mysterious dark matter interacts with itself. In the field of one of JWST's largest-area surveys, COSMOS-Web, an Einstein ring was discovered around a compact, distant galaxy. It turns out to be the most distant gravitational lens ever discovered by a few billion light-years.

------------------------------ 4604 - EINSTEIN RING - could explain dark matter?

- The remarkably dense JWST-ER1 galaxy and its Einstein ring, as captured by the James Webb Space Telescope last year. A fresh analysis of a remarkably massive yet compact galaxy from the early universe suggests that dark matter interacts with itself.

- The galaxy formed just 3.4 billion years after the Big Bang. It was first spotted last October in images snapped by JWST. At over 17 billion light-years from Earth, JWST-ER1g is the farthest-ever example of a perfect "Einstein ring", an unbroken circle of light around the galaxy, a result of light rays from a distant, unseen galaxy being bent due to the space-warping mass of JWST-ER1.

- The cosmic mirage is not just a pretty sight from a lucky alignment of galaxies; it also offers physicists a valuable probe for model-independent measurements of the mass enclosed within the ring's radius.

- By calculating just how much JWST-ER1g has warped space-time around itself, the discovery team had estimated that the galaxy weighs about 650 billion suns, which makes it a peculiarly dense galaxy for its size. By subtracting the visible stellar mass from the total inferred mass, physicists can measure how much of the galaxy is dark matter, an invisible substance thought to make up over 80% of all matter in our universe.

- Despite decades of observations and heaps of circumstantial evidence, the elusive substance is yet to be directly detected. In JWST-ER1g, the discovery team determined that dark matter explains just about half the mass gap, and that "additional mass appears to be needed to explain the lensing results.

- JWST-ER1g's unusually high density could be explained by a higher population of stars than currently thought. However, a contraction mechanism by which ordinary matter "collapses and condenses" into JWST-ER1g's dark matter halo could be packing "more dark matter mass in the same volume, resulting in higher density.

- The halo of dark matter, densest at the galaxy's center, is the gravitational glue that prevents spinning galaxies from flying apart. Furthermore, models incorporating a certain type of dark matter, in which its particles interact with themselves, provide "an excellent fit to the measurement of JWST-ER1.

- We don't yet know what dark matter actually is. Observational clues suggest it is a new kind of particle whose presence can only be inferred from its gravitational interactions with ordinary matter. Dark matter could be just one kind of particle or a complex variety of different types, like in normal matter, that perhaps operates in the presence of additional, unknown forces exclusive to dark matter.

- Self-interactions could explain extremely dense dark matter halos in certain galaxies, as well as puzzlingly low densities in others, both of which are unexplained by the prevailing "cold dark matter" theory.

- Physicists hope JWST can shed more light on dark matter, so to speak. The telescope's unprecedented infrared eyes peer further back in time than any other telescope, and its upcoming investigations of galaxies from the very early universe could reveal clues about dark matter particles and their behavior.

- We expect to see more surprises from JWST and learn more about dark matter soon.

- November 10, 2024 EINSTEIN RING - could explain dark matter? 4604

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

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

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--------------------- --- Monday, November 11, 2024 ---------------------------------

4603 - NEUTRON STARS COLLIDE - gives birth to atoms?

- 4603 - NEUTRON STARS COLLIDE - gives birth to atoms? - Neutron stars collide and explode to create black hole and 'birth atoms' For the first time, we see the creation of atoms; we can measure the temperature of the matter and see the microphysics in this remote neutron star explosion.

---------------------------------- 4603 - NEUTRON STARS COLLIDE - gives birth to atoms?

- Astronomers have witnessed the titanic collision between two neutron stars that resulted in the birth of the smallest black hole ever seen and forged precious metals like gold, silver, and uranium.

- This violent and powerful collision occurred 130 million light-years away from us in the galaxy “NGC 4993” was created with a range of instruments, including the Hubble Space Telescope. It will hopefully paint a picture of the "past, present, and future" of the mergers of these dense dead stars. This could reveal the origins of elements heavier than iron, which can't be forged in even the most massive stars.

- The outer layers of these stars are blasted away in supernova explosions, leaving a stellar remnant with a mass equal to between 1 and 2 suns crushed into a diameter of around 12 miles.

The collapse of the core forces electrons and protons together, creating a sea of particles called neutrons.

- This material is so dense that a mere sugar cube's worth of neutron star matter would weigh 1 billion tons if brought to Earth. That's about the same as cramming 150,000,000 elephants into the same space that a sugar cube occupies.

- The result is a system with two neutron stars orbiting each other. These objects are so dense that as they swirl around each other, they generate ripples in spacetime (the four-dimensional unification of space and time) called “gravitational waves? that ripple through space, carrying away angular momentum.

- As the system loses angular momentum, the orbit of the neutron stars tightens, and the neutron stars move closer to each other. This results in gravitational waves rippling away faster and faster, carrying away more and more angular momentum.

- Ejected particles like electrons and neutrons dance around the body, birthed by the colliding neutron stars, which rapidly collapse to form a black hole in a fog of plasma that cools over the next few days.

- Atoms in this cooling cloud of plasma quickly grab free neutrons via what is called the “rapid neutron capture process” (r-process) and also ensnare free electrons. This creates very heavy but unstable particles that rapidly decay. This decay releases the light that astronomers see as kilonovas, but it also creates lighter elements that are still heavier than iron, like gold, silver and uranium.

- This astrophysical explosion develops dramatically hour by hour, so no single telescope can follow its entire story. The viewing angle of the individual telescopes to the event is blocked by the rotation of the Earth. But by combining the existing measurements from Australia, South Africa, and the Hubble Space Telescope, we can follow its development in great detail.

November 4, 2024 NEUTRON STARS COLLIDE - gives birth to atoms? 4603

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--------------------- --- Monday, November 11, 2024 ---------------------------------

Saturday, November 9, 2024

- 4602 - MILKY WAY - James Webb latest findings? - James Webb telescope finds 1st possible 'failed stars' beyond the Milky Way. They could reveal new secrets of the early universe. They may have found dozens of elusive brown dwarfs , strange objects larger than planets but smaller than stars, beyond the Milky Way for the first time ever.

----------------- 4602 - MILKY WAY - James Webb latest findings?

- Astronomers zooming in on the young star cluster “NGC 602” in the nearby Small Magellanic Cloud (SMC) spotted what may be the first evidence of brown dwarfs ever seen outside the Milky Way.

- Brown dwarfs, or "failed stars," are peculiar objects that are bigger than the largest planets but not massive enough to sustain nuclear fusion like stars. Brown dwarfs seem to form in the same way as stars, they just don't capture enough mass to become a fully fledged star.

- “NGC 602” is a roughly 3 million-year-old star-forming cluster on the outskirts of the SMC, a satellite galaxy of the Milky Way that contains roughly 3 billion stars. (Our galaxy, in comparison, contains an estimated 100 billion to 400 billion stars.) Orbiting about 200,000 light-years from Earth, the SMC is one of the Milky Way's closest intergalactic neighbors.

- Previous observations of NGC 602 taken with the Hubble Space Telescope revealed that the cluster hosts a population of young, low-mass stars. Now, thanks to JWST's incredible sensitivity to infrared light, astronomers have fleshed out the picture of these stellar newborns, revealing precisely how much mass they have accumulated in their short lives.

- The results suggest that 64 stellar objects within the cluster have masses ranging between 50 and 84 times that of Jupiter. Brown dwarfs typically weigh between 13 and 75 Jupiter masses, making many of these objects prime candidates to be the first brown dwarfs spotted beyond our galaxy.

- These failed stars appear to have formed in much the same way as stars like the sun through the collapse of massive clouds of gas and dust. However, for a collapsed cloud to become a star, it must continue accumulating mass until it reaches an internal temperature and pressure high enough to trigger hydrogen fusion at its core combining hydrogen atoms into helium and releasing energy as light and heat in the process.

- Brown dwarfs never acquire enough mass to sustain permanent fusion, leaving them larger than a planet but smaller and dimmer than a star. This failure to ignite may be a common outcome in the universe. Astronomers have discovered about 3,000 brown dwarfs in the Milky Way but estimate that there may be as many as 100 billion in our galaxy alone, potentially making them as common as stars themselves.

- Studying this group of extragalactic failed stars further could help clarify why so many stars seemingly fail to ignite. But according to the researchers, these oddball objects could also reveal new insights about the early universe. NGC 602 is a young cluster containing low abundances of elements heavier than hydrogen and helium, so its composition is thought to be very similar to that of the ancient universe.

- By studying the young metal-poor brown dwarfs newly discovered in NGC 602, we are getting closer to unlocking the secrets of how stars and planets formed in the harsh conditions of the early Universe.

- November 7, 2024 MILKY WAY - James Webb latest findings? 4602

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--------------------- --- Saturday, November 9, 2024 ---------------------------------

Thursday, November 7, 2024

4601 - BIG BANG THEORY - what started it all?

- 4601 - BIG BANG THEORY - what started it all? - The Big Bang theory describes how the universe was born in a cataclysmic explosion almost 14 billion years ago. In a tiny fraction of a second, the observable universe grew by the equivalent of a bacterium expanding to the size of the Milky Way. This early universe was extraordinarily hot and extremely dense.

-------------------------------------- 4601 - BIG BANG THEORY - what started it all?

- In 1929, the American astronomer Edwin Hubble discovered that distant galaxies are moving away from each other, leading to the realization that the universe is expanding. If we were to wind the clock back to the birth of the cosmos, the expansion would reverse and the galaxies would fall on top of each other 14 billion years ago. This age agrees nicely with the ages of the oldest astronomical objects we observe.

- In 1964, Arno Penzias and Robert Wilson detected a particular type of radiation that fills all of space. This became known as the “cosmic microwave background” (CMB) radiation. It is a kind of afterglow of the Big Bang explosion, released when the cosmos was a mere 380,000 years old.

- The CMB provides a window into the hot, dense conditions at the beginning of the universe. Penzias and Wilson were awarded the 1978 Nobel Prize in Physics for their discovery. More recently, experiments at particle accelerators like the Large Hadron Collider (LHC) have shed light on conditions even closer to the time of the Big Bang.

- Our understanding of physics at these high energies suggests that, in the very first moments after the Big Bang, the four fundamental forces of physics that exist today were initially combined in a single force.

- The present day four forces are gravity, electromagnetism, the strong nuclear force and the weak nuclear force. As the universe expanded and cooled down, a series of dramatic changes, called phase transitions (like the boiling or freezing of water), separated these forces.

- Experiments at particle accelerators suggest that a few billionths of a second after the Big Bang, the latest of these phase transitions took place. This was the breakdown of electroweak unification, when electromagnetism and the weak nuclear force ceased to be combined. This is when all the matter in the universe assumed its mass.

- Moving on further in time, the universe is filled with a strange substance called “quark-gluon plasma”. This "primordial soup" was made up of quarks and gluons. These are sub-atomic particles that are responsible for the strong nuclear force. Quark-gluon plasma was artificially generated in 2010 at the Brookhaven National Laboratory and in 2015 at the LHC.

- Quarks and gluons have a strong attraction for one another and today are bound together as protons and neutrons, which in turn are the building blocks of atoms. However, in the hot and dense conditions of the early universe, they existed independently.

- The quark-gluon plasma didn't last long. Just a few millionths of a second after the Big Bang, as the universe expanded and cooled, quarks and gluons clumped together as protons and neutrons, the situation that persists today. This event is called “quark confinement”.

- As the universe expanded and cooled still further, there were fewer high energy photons (particles of light) in the universe than there had previously been. This is a trigger for the process called “Big Bang nucleosynthesis” (BBN). This is when the first atomic nuclei, the dense lumps of matter made of protons and neutrons and found at the centers of atoms, formed through nuclear fusion reactions, like those that power the sun.

- Back when there were more high energy photons in the universe, any atomic nuclei that formed would have been quickly destroyed by them (a process called photodisintegration). BBN ceased just a few minutes after the Big Bang, but its consequences are observable today.

- Observations by astronomers have provided us with evidence for the primordial abundances of elements produced in these fusion reactions. The results closely agree with the theory of BBN. If we continued on, over nearly 14 billion years of time, we would reach the situation that exists today.

- Scientists have no direct evidence for what came before the breakdown of electroweak unification (when electromagnetism and the weak nuclear force ceased to be combined). At such high energies and early times, we can only stare at the mystery of the Big Bang.

- When we go backwards in time through the history of the universe, the distances and volumes shrink, while the average energy density grows. At the Big Bang, distances and volumes drop to zero, all parts of the universe fall on top of each other and the energy density of the universe becomes infinite. Our mathematical equations, which describe the evolution of space and the expansion of the cosmos, become infested by zeros and infinities and stop making sense.

- We call this a “singularity”. Albert Einstein's theory of general relativity describes how spacetime is shaped. “Spacetime” is a way of describing the three-dimensional geometry of the universe, blended with time. A curvature in spacetime gives rise to gravity.

- But mathematics suggests there are places in the universe where the curvature of spacetime becomes unlimited. These locations are “singularities”. One such example can be found at the center of a black hole. At these places, the theory of general relativity breaks down.

- From 1965 to 1966, the British theoretical physicists Stephen Hawking and Roger Penrose presented a number of mathematical theorems demonstrating that the spacetime of an expanding universe must end at a singularity in the past: the Big Bang singularity.

- Space and time appear at the Big Bang singularity, so questions of what happens "before" the Big Bang are not well defined. As far as science can tell, there is no before; the Big Bang is the beginning of “time”.

- However, nature is not accurately described by general relativity alone, even though the latter has been around for more than 100 years and has not been disproven. “General relativity” cannot describe atoms, nuclear fusion or radioactivity. These phenomena are instead addressed by “quantum theory”.

- Theories from "classical" physics, such as relativity, are deterministic. This means that certain initial conditions have a definite outcome and are therefore absolutely predictive. Quantum theory, on the other hand, is probabilistic. This means that certain initial conditions in the universe can have multiple outcomes.

- “Quantum theory” is somewhat predictive, but in a probabilistic way. Outcomes are assigned a probability of existing. If the mathematical distribution of probabilities is sharply peaked at a certain outcome, then the situation is well described by a "classical" theory such as general relativity. But not all systems are like this. In some systems, for example atoms, the probability distribution is spread out and a classical description does not apply.

- In the vast majority of cases, gravity is well described by classical physics. Classical spacetime is smooth. However, when curvature becomes extreme, near a singularity, then the quantum nature of gravity cannot be ignored. Here, spacetime is no longer smooth, similar to a carpet which looks smooth from afar but up-close is full of fibers and threads.

- Thus, near the Big Bang singularity, the structure of spacetime ceases to be smooth. Mathematical theorems suggest that spacetime becomes overwhelmed by features of hooks, loops and bubbles. This rapidly fluctuating situation is called “spacetime foam”.

- In “spacetime foam”, causality does not apply, because there are closed loops in spacetime where the future of an event is also its past (so its outcome can also be its cause). The probabilistic nature of quantum theory suggests that, when the probability distribution is evenly spread out, all outcomes are equally possible and the comfortable notion of causality we associate with a classical understanding of physics is lost.

- Therefore, if we go back in time, just before we encounter the Big Bang singularity, we find ourselves entering an epoch where the quantum effects of gravity are dominant and causality does not apply. This is called the “Planck epoch”.

- Time ceases to be linear, going from the past to the future, and instead becomes wrapped, chaotic and random. This means the question "why did the Big Bang occur?" has no meaning, because outside causality, “events do not need a cause to take place”.

- In order to understand how physics works at a singularity like the Big Bang, we need a theory for how gravity behaves according to quantum theory. Unfortunately, we do not have one. There are a number of efforts on this front like “loop quantum gravity” and “string theory”.

- However, these efforts are at best incomplete, because the problem is notoriously difficult.

So how did our expanding and largely classical universe ever escape from spacetime foam? This brings us to “cosmic inflation”. This is defined as a period of accelerated expansion in the early universe. It was first introduced by the Russian theoretical physicist Alexei Starobinsky in 1980 and in parallel, that same year, by the American physicist Alan Guth, coined the name.

- “Inflation” makes the universe large and uniform, according to observations. It also forces the universe to be spatially flat, which is an otherwise unstable situation, but which has also been confirmed by observations. Inflation provides a natural mechanism to generate the primordial irregularities in the density of the universe that are essential for structures such as galaxies and galaxy clusters to form.

- Precision observations of the “cosmic microwave background” in recent decades have spectacularly confirmed the predictions of “inflation”. We also know that the universe can indeed undergo accelerated expansion, because in the last few billion years it started doing it again.

- If the conditions for inflation arise (by chance) in a patch of fluctuating spacetime, as can occur with spacetime foam, then this region inflates and starts conforming to classical physics.

According to an idea first proposed by the Russian-American physicist Andrei Linde, inflation is a natural, and perhaps inevitable, consequence of chaotic initial conditions in the early universe.

- The point is that our classical universe could have emerged from chaotic conditions, like those in spacetime foam, by experiencing an initial boost of inflation. This would have set off the expansion of the universe. In fact, the observations by astronomers of the CMB suggest that the initial boost is explosive, since the expansion is exponential during inflation.

- The 14 billion-year story of our universe begins with a cataclysmic explosion everywhere in space, which we call the Big Bang. That much is beyond reasonable doubt. This explosion is really a period of explosive expansion, which we call cosmic inflation. What happens before inflation, though? Is it a spacetime singularity, is it spacetime foam? The answer is largely unknown.

- In fact, it might even be unknowable, because there is a mathematical theorem which forbids us from accessing information about the onset of inflation, much like the one that prevents us from knowing about the interiors of black holes. So, from our point of view, cosmic inflation is the Big Bang, the explosion that started it all.

- November 5, 2024 BIG BANG THEORY - what started it all 4601

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