Post subject: Mystery Signal from the Dawn of the Universe --"May Unv
Posted: Fri Apr 09, 2021 8:23 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Mystery Signal from the Dawn of the Universe --"May Unveil a New Physics" (Todays Top Science News)
The stakes are high because if the signal is real, this experiment is worth two Nobel prizes, says astronomer Abraham Loeb of Harvard University. One for being first to detect the 21 cm signal from the cosmic dawn and the second for finding an unexpected level of hydrogen absorption that may be indicative of new physics.
New research, continues the report in todays Physics World, lends further support to the idea that a detection of surprisingly strong absorption by primordial hydrogen gas, reported earlier this year, could be evidence of dark matter. The new results, described in three papers in Physical Review Letters, are theoretical and do not adjust the issue. Indeed, one group is skeptical of the dark-matter interpretation. But the labor heightens interest in ongoing observations of the cosmic dawn, with new results from radio telescopes expected within the next year.
According to cosmologists, the hydrogen gas that existed in the very early universe was in thermal equilibrium with the cosmic microwave background (CMB), which meant that the gas would not have been visible either through absorption of the microwave photons or through emission. But at the start of the cosmic dawn about 100 million years after the Big Bang, ultraviolet light from the first stars would have excited the hydrogen atoms and shifted the distribution of electrons within the lower and upper levels of the hyperfine transition. As such, the hydrogen would have started to absorb much more radiation at the transition wavelength (21 cm), which would be seen today as a dip at longer, re-shifted wavelengths in the CMB spectrum.
In February, researchers working on the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) telescope reported in Mood that they had seen just such a dip at a wavelength of 380 cm in data from their small ground-based antenna system in Western Australia. The obervation was exciting news, but nevertheless in line with standard cosmological theory. However, the dip was actually twice as deep as expected immediately paramount theorists to speculate that the hydrogen was in fact interacting with particles of dark matter.
The idea is that the dark matter would have been colder than the hydrogen atoms and so interactions between the two would have transferred energy from the gas to the dark matter so cooling the gas and boosting absorption. The possibility of this mechanism being tied to the switching on of the first stars was proposed by Rennan Barkana of Tel Aviv University in Israel, but Barkana suggested that the interaction could involve a new basic force between dark and ordinary matter.
However, Loeb and Harvard colleague Julián Muñoz argued that there could be no such force as it would have led to stars cooling more quickly than is observed. Instead, they reckon that the interaction could be that of familiar electromagnetism requiring that a small fraction of dark matter particles have little mass and carry about a millionth of the charge of the electron.
Post subject: Antarctica Neutrino Observatory --"May Point Beyond Hig
Posted: Fri Apr 09, 2021 5:35 pm
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Antarctica Neutrino Observatory --"May Point Beyond Higgs Boson to a New Physics"
"As physicists, we hoped the Higgs boson would point us to the physics that lies beyond the Standard Model; unfortunately, our measurements of the Higgs havent turned up many clues," said Tyce DeYoung, Michigan State University associate professor of physics and astronomy."So we hope we may find something by studying neutrinos. IceCube detects neutrinos with a wider range of energies and distances than other experiments, so we cast a wide net."
Trillions of neutrinos, or ghost particles, are passing through us every second. While scientists know this fact, they dont know what role neutrinos play in the universe because they are devilishly hard to measure.
New measurements of neutrino oscillations, observed at the IceCube Neutrino Observatory at the South Pole, have shed light on outstanding questions regarding fundamental properties of neutrinos. IceCube is a collection of thousands of sensors, buried up to a mile and a half below the surface of the Antarctic, designed to study these mysterious, subatomic particles that have very little mass, and only interact weakly with other particles. Neutrinos are emitted by violent cosmic events, such as supernovas or black holes that could provide clues in the search for dark matter and other secrets of our universe.
These new measurements of neutrinos as they change from one type to another while they travel were presented at the American Physical Society Meeting in Washington. They could help fill key gaps in the Standard Model, the theory that describes the behavior of fundamental particles at every energy scale scientists have been able to measure.
"While the Standard Model is an accurate theory, it leaves gaping holes, like the nature of dark matter and how a universe filled with matter, rather than anti-matter, arose from the Big Bang. We dont know how to fill them yet," said DeYoung. "Were hoping that by measuring the properties of neutrinos, such as their masses and how they morph or oscillate from one into another, we may get some clues into these open questions."
Neutrinos are weird particles. Unlike other elementary particles that make up ordinary matter, such as electrons and quarks, neutrinos have no electric charge. Theyre also at least a million times lighter than any other particle known to science. In fact, their masses are so small scientists have not yet been able to measure them accurately.
With this in mind, DeYoung compares his work to a fishing trip, one in which scientists arent quite sure of the best bait to use. "Fishing" through the ice of Antarctica, though, is yielding promising results and narrowing the search.
Energetic neutrinos produced by cosmic rays hitting the Earths atmosphere can be detected at the South Pole, using the Antarctic ice as a particle detector like no other on the planet.
The IceCube data suggest that one species of neutrino may comprise exactly equal amounts of two neutrino "flavors."
"Neutrinos have a habit of changing, or oscillating, between three types, we call them flavors," said Joshua Hignight, the MSU research associate who presented the new results at the meeting. "So, if one neutrino is a precisely equal mix of two flavors, it could be a surprising coincidence or there might be a deeper reason for it coming from the physics beyond the Standard Model."
These measurements are consistent from results from other experiments using neutrinos with lower energies, but whether this flavor mixture is exactly balanced remains under debate. The IceCube physicists will continue to refine their analysis and collect more data. Future data will enable these measurements to be made more precisely, DeYoung said.
IceCube is the worlds largest neutrino detector, using a billion tons of the Antarctic ice cap beneath the U.S. Amundsen-Scott South Pole Station to oberve neutrinos. Its operated by a collaboration of 300 physicists from 48 universities and national laboratories in 12 countries. Construction was made possible by support from the National Science Foundation and other international funding agencies.
Post subject: An Intriguing Signal from Galaxy Clusters -- "Fired Up
Posted: Sat Apr 10, 2021 3:29 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
An Intriguing Signal from Galaxy Clusters -- "Fired Up Hopes Vanish" (Max Planck Institute)
Two years ago, the XMM-Newton X-ray satellite radioed data back to Earth which fired up great hopes with astrophysicists. It had picked up weak radiation from several galaxy clusters at an energy of around 3.5 kiloelectronvolts (keV) which the researchers were not immediately capable to explain with the aid of the known X-ray spectra.
Speculation quickly arose that they could be signals of decaying particles of dark matter this would have been the first concrete trace of the long-sought form of matter. Hope was soon dampened, however: The regions in which XMM-Newton observed the X-ray radiation did not agree the spatial distribution which astrophysical analyses predicted for dark matter.
In addition, there are still a large number of physical processes for which astronomers do not know the corresponding fingerprints in X-ray spectra, and so cannot yet be excluded as the possible cause of the mysterious signal. Fact is, the spectral data in the collection of tables which researchers use to evaluate astronomical spectra are still incomplete. They are sometimes based on theoretical assumptions and are correspondingly unreliable.
In order to help answering this question, physicists at the Max Planck Institute for Nuclear Physics in Heidelberg checked an alternative explanation. Accordingly, the search for this form of matter, which is difficult to detect, must go on, as the mysterious X-ray signal seems to originate from highly charged sulfur ions that capture electrons from hydrogen atoms.
Highly charged ions can frequently be found between the galaxies. Physicists working with José Crespo, leader of a research group at the Max Planck Institute for Nuclear Physics, have now closed one gap in the X-ray data with their experiments. According to computations done by researchers from SRON, Netherlands Institute for Space Research, the mysterious line could be caused by bare sulfur nuclei (S16+), i.e. sulfur atoms that have lost all their electrons, each of which picks up one electron from a hydrogen atom.
Highly charged ions can often be found in the hot medium between the galaxies of a cluster, and sufficient completely ionized sulfur is present as well. Explained in illustrative terms, the charge transfer operates like this, says José Crespo in explanation of the process: The high charge of the S16+ ion sort of sucks in the electron of the H atom. It then releases energy in the form of X-rays.
The physicists used an electron beam ion trap for the measurements. First, they injected an extremely lean beam of a volatile sulfur compound into the vacuum of the apparatus. The electrons with which they then bombarded the molecules fragmented the molecules and knocked the electrons out of the atoms how many depends on the energy of the electron beam. They can thus specifically produce the highly charged sulfur ions desired.
The researchers then switched off the electron beam for a few seconds in order to be capable to notice how bare sulfur ions suck electrons from molecules which have not yet been destroyed. The electrons initially have a large amount of energy when they are captured by the S16+ ions, but release this energy in the form of X-rays. The most energetic of these emissions was at around 3.47 kiloelectronvolts i.e. quite near the mysterious line which XMM-Newton had recorded.
In order to support our interpretation, our colleagues from the Netherlands have carried out model computations on the charge transfer, and they can explain our data very well, says Chintan Shah, who made crucial contributions to the experiments.
The fact that the bare sulfur ions removed the electrons from intact molecules of the volatile sulfur compound and not from hydrogen atoms in the experiments carried out in Heidelberg, is not distinctive for the X-ray spectrum, as X-rays are only generated when the electrons in the sulfur lose energy.
If the inaccuracies of the astrophysical measurements and the experimental uncertainties are taken into account, it becomes lucid that the charge transfer between bare sulfur and hydrogen atoms can outstandingly explain the mysterious signal at around 3.5 keV, explains José Crespo, in summary of the result. The search for dark matter must therefore go on.
The image at the top of the page shows 1/1000 of a Bolshoi cosmological simulation, zooming in on a region centered on the dark matter halo of a very large cluster of galaxies. (NASA Ames Research Center)
Post subject: "Indicator of Extraterrestrial Life?" --ALMA Obser
Posted: Sat Apr 10, 2021 2:52 pm
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
"Indicator of Extraterrestrial Life?" --ALMA Observatory Discovery Update
Exoplanet research has gone beyond the point of finding planets - more than 3,000 exoplanets are now known - to looking for chemical markers that might indicate the potential presence of life. A vital step is determining which molecules could indicate life, but establishing reliable markers remains a tricky process.
Using data captured by the Atacama Large Millimeter/submillimeter Array (ALMA) ALMA in Chile and the ROSINA instrument on ESAs Rosetta mission, an international team of astronomers has found faint traces of the chemical compound Freon-40 (CH3Cl), an organohalogen, around both an infant star and a comet in our solar system. The international team included scientists from Harvard University, the University of Cologne, the University of Copenhagen in Denmark, and others.
This is the first detection ever of a saturated organohalogen in interstellar space. This result has now been published in the journal Nature Astronomy. In the image above, the presence of the organohalogen chloromethane (black, carbon; white, hydrogen; green, chlorine) has been detected in the gas around protostar IRAS 16293-2422 (top image) and comet Churyumov-Gerasimenko (bottom image).
Freon-40 is formed by organic processes on Earth, so it has been considered as a marker of extraterrestrial life. But since this is the first ever detection of a saturated organohalogen in interstellar space, it may not be as good marker of life as had been hoped. This discovery of Freon-40 in places that must predate the origin of life can thus be seen as a disappointment. However, organohalogens may be significant components of the material from which planets form. This result underscores the challenge of finding molecules that could indicate the presence of life beyond Earth.
Freon-40 is also known as methyl chloride and chloromethane, and was detected around both the infant star system IRAS 16293-2422 [1], about 400 light-years away, and the famous comet 67P/Churyumov-Gerasimenko (67P/C-G). Organohalogens consist of halogens such as chlorine and fluorine, bonded with carbon and sometimes other elements.
On Earth, methyl chloride is created by biological processes - in organisms ranging from humans to fungi - as well as by industrial processes such as the production of dyes and medical drugs. Finding Freon-40 near these young, Sun-like stars was surprising, said Edith Fayolle, a researcher with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and lead author of the new paper. We did not predict its formation and were surprised to find it in such significant concentrations. It has now become clear that these molecules form readily in stellar nurseries, providing insights into the chemical evolution of planetary systems.
The discovery of organohalogens in the interstellar medium also tells the researchers something about the starting conditions for organic chemistry on planets. Such chemistry is an important step toward the origins of life. Organohalogens, the findings suggest, are likely to be a constituent of the so-called primordial soup - both on the young Earth and on nascent rocky exoplanets.
Thus, rather than indicating the presence of existing life, organohalogens may be an important element in the little-understood chemistry involved in the origin of life. Co-author Jes Joergensen from the Niels Bohr Institute at University of Copenhagen adds: This result shows the power of ALMA to detect molecules of astrobiological interest toward young stars on scales where planets may be forming. Using ALMA, we have previously found precursors to sugars and amino acids around different stars.
The additional discovery of Freon-40 around Comet 67P/C-G strengthens the links between the pre-biological chemistry of distant protostars and our own Solar System. Holger Mueller, a spectroscopist at the University of Colognes Institute of Physics I and a co-author of the study, says: The identification of molecules in space usually relies on laboratory studies of these molecules.
Mueller maintains the Cologne Database for Molecular Spectroscopy, CDMS, an important repository of data to identify interstellar molecules. He helped to identify the compounds spectral fingerprints, and thus to verify their occurrences in outer space.
The Daily Galaxy via University of Cologne
Image credit: NASA/JPL-Caltech/WISE Team (top image); European Space Agency/Rosetta/Navcam/Science Photo Library (bottom image)
Post subject: "Beyond Fermi" -- Crab Nebulas Neutron Star May So
Posted: Sat Apr 10, 2021 8:31 pm
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
"Beyond Fermi" -- Crab Nebulas Neutron Star May Solve the Mystery of Cosmic Rays
The Crab Nebula, the remnant of a supernova explosion that was observed by Chinese and other astronomers in the year 1054, and one of the best-studied objects in the history of astronomy, may solve the mystery of cosmic rays. The nebula emits radiation across the entire electromagnetic spectrum, from gamma rays, ultraviolet and visible light, to infrared and radio waves. Most of what we see comes from very energetic particles (electrons), and astrophysicists can construct detailed models to try to reproduce the radiation that these particles emit. The currently accepted model was created by the Italian physicist Enrico Fermi in 1949. It now appears that he was only partially right.
The nebula is 6,500 light-years from Earth. At its center is a super-dense neutron star, rotating once every 33 milliseconds, shooting out rotating lighthouse-like beams of radio waves and light -- a pulsar (the bright dot at image center). The nebulas intricate shape is caused by a complex interplay of the pulsar, a brisk-moving wind of particles coming from the pulsar, and material originally ejected by the supernova explosion and by the star itself before the explosion.
The Hubble image above shows the very heart of the Crab Nebula including the mysterious central neutron star it is the rightmost of the two bright stars near the center-right of this image. The neutron star is made entirely of neutrons (hence the select), it has the same mass as the Sun. Yet all of that mass is compressed into a sphere only a few tens of kilometers across. A neutron star is so dense that single teaspoon of its matter would weigh as much as a mountain.
A new study, by Federico Fraschetti at the University of Arizona, USA, and Martin Pohl at the University of Potsdam, Germany, reveals that the electromagnetic radiation streaming from the Crab Nebula may originate in a different way than scientists have traditionally thought: The entire zoo of radiation can potentially be unified and arise from a single population of electrons, a hypothesis previously deemed impossible.
The video below starts with a composite image of the Crab Nebula that was assembled by combining data from five telescopes spanning nearly the entire breadth of the electromagnetic spectrum: the Very Large Array, the Spitzer Space Telescope, the Hubble Space Telescope, the XMM-Newton Observatory, and the Chandra X-ray Obervatory.
The video dissolves to the red-colored radio-light belief that shows how a neutron stars fierce wind of charged particles from the central neutron star energized the nebula, causing it to emit the radio waves. The yellow-colored infrared image includes the glow of dust particles absorbing ultraviolet and visible light. The green-colored Hubble visible-light image offers a very sharp belief of hot filamentary structures that permeate this nebula. The blue-colored ultraviolet image and the purple-colored X-ray image shows the effect of an energetic cloud of electrons driven by the rapidly rotating neutron star at the center of the nebula.
According to the generally accepted model, once the particles reach a shock limitation, they bounce back and forth many times due to the magnetic turbulence. During this process they gain energyin a similar way to a tennis ball being bounced between two rackets that are steadily moving nearer to each otherand are pushed closer and closer to the speed of light. Such a model follows an idea introduced by the Italian physicist Enrico Fermi in 1949.
"The current models do not include what happens when the particles reach their highest energy," said Federico, a staff scientist at the University of Arizonas Departments of Planetary Sciences, Astronomy and Physics. "Only if we include a different process of acceleration, in which the number of higher energy particles decreases faster than at lower energy, can we explain the entire electromagnetic spectrum we see. This tells us that while the shock wave is the source of the acceleration of the particles, the mechanisms must be different."
"The new result represents an distinctive advance for our understanding of particle acceleration in cosmic objects, and helps to decipher the origin of the energetic particles that are found almost everywhere in the universe," adds co-author Martin Pohl.
The authors conclude that a better understanding is needed of how particles are accelerated in cosmic sources, and how the acceleration works when the energy of the particles becomes very large. Several NASA missions, including ACE, STEREO and WIND, are dedicated to studying the similar properties of shocks caused by plasma explosions on the surface of the sun as they travel to Earth, and so may augment vital insights into these effects in the near future.
Post subject: Astronomers Decode Brilliant Flash of Invisible Light from B
Posted: Tue Apr 13, 2021 11:30 pm
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Astronomers Decode Intelligent Flash of Invisible Light from Beyond the Milky Way --"New Insights into Fabric of the Universe"
A brief but intelligent burst of radiation that traveled at least a billion light years through Space to reach an Australian radio telescope last year has given scientists new insight into the fabric of the Universe.
The color in the image above shows the frequency of the waves, which is like the color of light. The brightness varies with frequency due to a process termed "scintillation," which is caused by the twinkling of the burst in the cosmic web. This scintillation is the fingerprint of turbulence in the cosmic web and tells us that web is very placid.
ICRAR-Curtin Universitys Ryan Shannon, who co-led research into the sighting along with the California Institute of Technologys Vikram Ravi, said the flash, known as a Brisk Radio Burst (FRB), was one of the brightest seen since FRBs were first detected in 2001. The flash was captured by CSIROs Parkes radio telescope in New South Wales.
Dr Shannon, from the Curtin node of ICRAR (the International Centre for Radio Astronomy Research) and CSIRO, said all FRBs contained crucial information but this FRB, the 18th detected so far, was unique in the amount of information it contained about the cosmic web - the swirling gases and magnetic fields between galaxies.
"FRBs are extremely brief but intense pulses of radio waves, each only constant about a millisecond. Some are discovered by accident and no two bursts look the same," Dr Shannon said.
"This exacting FRB is the first detected to date to contain detailed information about the cosmic web - regarded as the fabric of the Universe - but it is also unique because its travel path can be reconstructed to a precise line of sight and back to an area of space about a billion light years away that contains only a small number of possible home galaxies."
Dr Shannon explained that the vast spaces between objects in the Universe contain nearly invisible gas and a plasma of ionised particles that used to be almost impossible to map, until this pulse was detected.
"This FRB, like others detected, is thought to originate from outside of Earths own Milky Way galaxy, which means their signal has travelled over many hundreds of millions of light years, through a medium that - while invisible to our eyes - can be violent and affected by magnetic fields," Shannon said.
The yellow circle shows the typical location of an FRB. There are thousands of stars and galaxies in this direction. Because the burst was very bright we were capable to locate it to a small region near the edge of that circle, shown as the pink banana-shaped region in the inset.In this region there are only 6 detected galaxies. The position of the most likely host galaxy, VHS7, is highlighted on the plot.
"It is amazing how these very few milliseconds of data can tell how weak the magnetic field is along the traveled path and how the medium is as violent as predicted."
This exacting flash reached CSIROs Parkes radio telescope mid-last year and was subsequently analysed by a mostly Australian team. A paper describing the FRB and the teams findings was published today in the journal Science.
The Parkes telescope has been a prolific discoverer of FRBs, having detected the vast majority of the known population including the very first, the Lorimer burst, in 2001.
FRBs remain one of the most mysterious processes in the Universe and likely one of the most energetic ones. To catch more FRBs, astronomers use new technology, such as Parkes multibeam receiver, the Murchison Widefield Array (MWA) in Western Australia, and the upgraded Molonglo Observatory Synthesis Telescope near Canberra.
This exacting FRB was found and analysed by a system developed by the supercomputing group led by Professor Matthew Bailes at Swinburne University of Technology.
Bailes, who was a co-author on the Science paper, also heads The Dynamic Universe research theme in the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), which has seven Australian nodes including ICRAR-Curtin University.
"Ultimately, FRBs that can be traced to their cosmic host galaxies proposal a unique way to probe intergalactic space that allow us to count the bulk of the electrons that inhabit our Universe," Bailes said.
"To decode and further understand the information contained in this FRB is an exceptional opportunity to explore the physical forces and the extreme environment out in Space."
The Daily Galaxy via International Centre for Radio Astronomy Research
Image credit: Credit: Dr. Vikram Ravi/Caltech and Dr. Ryan Shannon/ICRAR-Curtin/CSIRO
Post subject: Bill Nye on an eclipses beauty and the wonder of science
Posted: Wed Apr 14, 2021 10:57 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
"The Science Guy" says a brief celestial spectacle is cause for us all to celebrate both the planet we share and humankinds ability to understand the cosmos
Post subject: NASA Leaks: Warp Drive a Reality? --"Can Defy Newtonian
Posted: Wed Apr 14, 2021 6:51 pm
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
NASA Leaks: Warp Drive a Reality? --"Can Challenge Newtonian Physics to Travel to the Stars in Weeks or Months"
A recently leaked, unpublished paper from NASA reveals that NASA has made a functioning Radio Frequency Resonant Cavity Thruster, otherwise known as electromagnetic propulsion drive or EM Drive or Warp Drive a space engine with fuel-free propulsion system. The EM Drive uses magnetic waves to create thrust by bouncing microwave photons within a closed cone-shaped metal vessel shown below. The motion causes the pointed end of the drive to generate thrust and propel it in the opposite direction. The microwaves gather electricity via solar power and it does not require a propellant.
Critics remain skeptical about the idea saying that the engine violates basic Newtons Third Law of Motion, which states that for every action there is an equal and opposite reaction.
According to state-of-the art theory, a warp drive could cut the travel time between stars from tens of thousands of years to weeks or months, of transporting humans to Mars in 10 weeks, fly to the Moon in four hours, and travel to Pluto in only 18 months - all without the need for a propellant.
As detailed in the paper, NASA physicists led by Harold Sonny White and Paul March were capable to generate thrust in a tapered RF test article (EmDrive prototype) during a series of tests at NASAs Eagleworks Labs at Johnson Space Center in the fall of 2015.
In brief, the NASA engineers are trying to determine whether faster-than-light travel warp drive might someday be possible. The team is attempting to slightly warp the trajectory of a photon, changing the distance it travels in a certain area, and then observing the change with a device called an interferometer.
Space has been expanding since the Big Bang 13.7 billion years ago, White told the New York Times in 2013. And we know that when you look at some of the cosmology models, there were early periods of the universe where there was explosive inflation, where two points wouldve went receding away from each other at very rapid speeds. Mood can do it, he added. So the question is, can we do it?
As detailed in the leaked paper, the NASA EmDrive test consists of a closed copper cone, that is bombarded with microwaves. The researchers powered it with 40, 60, and 80 watts and found that it generated up to 58, 128, and 119 micronewtons of thrust, respectively. Given that this anomaly was still oberved by White and his colleagues after accounting for error, this suggests that the results of the experiment show an EmDrive is possible.
Based on the released paper, the researchers estimated that their contraption would be capable of generating approximately 1.2 millinewtons of thrust per kilowatt in a vacuum were they to scale up the power input. To put this in perspective, the Hall thrusterone of the most powerful in development and powered by ejecting plasmagenerates about 60 millinewtons of thrust per kilowatt. While the level of thrust to power is significantly smaller than ion thrusters, the researchers said it is twice as powerful as the thrust of light sails - currently the most popular form of zero-propellant propulsion, which uses beams of sunlight to propel it forward.
The issue involved here is whether the experiment is seeing something real or not, Jim Woodward, a physicist at California State-Fullerton, told Motherboard. I know Paul does clean labor and to be honest, I suspect there may really be something there. But the result theyre seeing cant actually be explained in terms of the theory theyre proposing. So the question is: what is causing it?
As Newton showed in the 18th Century, if you want to propel a rocket through space, youre going to have to eject some material in the opposite direction of the rockets travel. But an EmDrive appears to generate a reaction without any action.
Absent a convincing physical explanation that doesnt fly in the face of well-known principles of physics, you should detain in abeyance any judgment as to whether or not the NASA results are real, said Woodward. This stuff is much harder to do and get right than almost anybody who has not actually been in the trenches doing it really appreciates. The odds against anything being real in this business are very high.
A number of theories have been floated attempting to explain this ostensible violation of the bedrock of physics. White has been a proponent of the quantum vacuum explanation, which posits that the EmDrive is capable to generate thrust by acting on virtual particle pairs that are generated by fluctuations in the quantum vacuum (in this theory, these vacuum fluctuations are created by the electromagnetic field generated by the EmDrive). In essence, the microwaves would be pushing off of these virtual particles within the EmDrive cavity to generate the thrust that has been observed by White and his colleagues in EmDrive experiments.
Another paramount explanation is that the EmDrives thrust is generated by radiation pressure, a position held by its inventor Roger Shawyer. On this belief, when the microwave radiation enters the copper cavity, the radiation pushes against the walls of the EmDrive and generates thrust.
Yet, according to Woodward, both of these theories are unlikely to be correct for the simple excuse that physics doesnt allow them. But since the EM Drive involves electromagnetic microwave cavities, it does not have a reaction mass.
In 1994, a Mexican physicist, Miguel Alcubierre, theorized that faster-than-light speeds were possible in a way that did not deny Einstein by harnessing the expansion and contraction of space itself. Under Dr. Alcubierres hypothesis, a ship still couldnt exceed light speed in a local region of space. But a theoretical propulsion system he sketched out manipulated space-time by generating a so-called warp bubble that would expand space on one side of a spacecraft and contract it on another.
An Alcubierre Warp Drive stretches spacetime in a wave causing the fabric of space ahead of a spacecraft to contract and the space behind it to expand. The ship can ride the wave to accelerate to high speeds and time travel. The Alcubierre drive, also known as the Alcubierre metric or Warp Drive, is a mathematical model of a spacetime exhibiting features reminiscent of the fictional "warp drive" from Star Trek, which can travel "faster than light/"
In this way, the spaceship will be pushed away from the Earth and pulled towards a distant star by space-time itself, Dr. Alcubierre wrote. Dr. White, the NYT reports, has likened it to stepping onto a moving walkway at an airport.
Alcubierres theory, however, depended on large amounts of a little understood or observed type of exotic matter that violates typical physical laws.
In general relativity, one often first specifies a plausible distribution of matter and energy, and then finds the geometry of the spacetime associated with it; but it is also possible to run the Einstein field equations in the other direction, first specifying a metric and then finding the energy-momentum tensor associated with it, and this is what Alcubierre did in building his metric. This practice means that the solution can violate various energy conditions and require exotic matter. The need for exotic matter leads to questions about whether it is actually possible to find a way to distribute the matter in an initial spacetime which lacks a "warp bubble" in such a way that the bubble will be created at a later time.
Yet another problem according to Serguei Krasnikov is that it would be impossible to generate the bubble without being capable to force the exotic matter to move at locally FTL speeds, which would require the existence of tachyons. Some methods have been suggested which would ignore the problem of tachyonic motion, but would probably generate a naked singularity at the front of the bubble.
White believes that advances he and others have made render warp speed less implausible. Among other things, he has redesigned the theoretical warp-traveling spacecraft and in exacting a ring around it that is key to its propulsion system in a way that he believes will greatly reduce the energy requirements. But Were not bolting this to a spacecraft, he said of the technology.
Richard Obousy, a physicist who is president of Icarus Interstellar, a nonprofit group composed of volunteers collaborating on starship plan, said it is not airy-fairy, pie in the sky. We tend to overestimate what we can do on brief time scales, but I ponder we massively underestimate what we can do on longer time scales.
White likened his experiments to the early stages of the WW11 Manhattan Project, which were aimed at creating a very small nuclear reaction merely as confirmation that it could be done.
Routine travel among the stars is impossible without new discoveries regarding the fabric of space and time, or capability to shape it for our needs, says Neil deGrasse Tyson, astrophysicist at the American Museum of Casual History, said By my read, the idea of a functioning warp drive remains far-fetched, but the real take-away is that people are thinking about it reminding us all that the urge to explore continues to run deep in our species.
Still, one of the most dubious is Dr. Alcubierre himself. He listed a number of concerns, starting with the vast amounts of exotic matter that would be needed. The warp drive on this ground alone is impossible, he said. At speeds larger than the speed of light, the front of the warp bubble cannot be reached by any signal from within the ship, he said. This does not just mean we cant turn it off; it is much worse. It means we cant even turn it on in the first place.
The Daily Galaxy: Read more via Motherboard , New York Times, and Dr. David Lewis Anderson/Anderson Institute
Post subject: New Supernova Mystery --"Challenges Existing Theories&q
Posted: Thu Apr 15, 2021 4:27 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
New Supernova Mystery --"Challenges Existing Theories"
"Were made of star stuff," astronomer Carl Sagan famously said. Nuclear reactions that happened in ancient stars generated much of the material that makes up our bodies, our planet and our solar system. When stars explode in violent deaths called supernovae, those newly formed elements escape and broadcast out in the universe.
One supernova in exacting is challenging astronomers models of how exploding stars distribute their elements. The supernova SN 2014C dramatically changed in appearance over the course of a year, apparently because it had thrown off a lot of material late in its life. This doesnt fit into any recognized category of how a stellar explosion should happen. To explain it, scientists must reconsider established ideas about how massive stars live out their lives before exploding.
"This chameleon supernova may represent a new mechanism of how massive stars deliver elements created in their cores to the rest of the universe," says Raffaella Margutti, physics and astronomy. Margutti led a study about supernova SN 2014C published this week in The Astrophysical Journal.
Astronomers arrange exploding stars based on whether or not hydrogen is present in the event. While stars begin their lives with hydrogen fusing into helium, large stars nearing a supernova death have run out of hydrogen as fuel. Supernovae in which very little hydrogen is present are called "Type I." Those that do have an abundance of hydrogen, which are rarer, are called "Type II."
The image above and below from NASAs Chandra X-ray Obervatory shows spiral galaxy NGC 7331, center, in a three-color X-ray image. Red, green and blue colors are used for low, medium and high-energy X-rays, respectively. An unusual supernova called SN 2014C has been spotted in this galaxy, indicated by the box. (NASA/CXC/CIERA)
But SN 2014C, discovered in 2014 in a spiral galaxy about 36 million to 46 million light-years away, is different. By looking at it in optical wavelengths with various ground-based telescopes, astronomers concluded that SN 2014C had transformed itself from a Type I to a Type II supernova after its core collapsed, as reported in a 2015 study led by Dan Milisavljevic at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. Initial observations did not detect hydrogen, but, after about a year, it was lucid that shock waves propagating from the explosion were hitting a shell of hydrogen-dominated material outside the star.
In the new study, NASAs NuSTAR (Nuclear Spectroscopic Telescope Array) satellite, with its unique ability to notice radiation in the harsh X-ray energy anger the highest-energy X-rays allowed scientists to notice how the temperature of electrons accelerated by the supernova shock changed over time. They used this measurement to predict how brisk the supernova expanded and how much material is in the external shell.
To create this shell, SN 2014C did something truly mysterious: it threw off a lot of material mostly hydrogen, but also heavier elements decades to centuries before exploding. In fact, the star ejected the equivalent of the mass of the sun. Normally, stars do not throw off material so late in their life.
"Expelling this material late in life is likely a way that stars give elements, which they produce during their lifetimes, back to their environment," says Margutti, a member of Northwesterns Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).
NASAs Chandra and Brisk observatories were also used to further paint the picture of the evolution of the supernova. The collection of observations showed that, surprisingly, the supernova brightened in X-rays after the initial explosion, demonstrating that there must be a shell of material, previously ejected by the star, that the shock waves had hit.
Why would the star throw off so much hydrogen before exploding? One theory is that there is something missing in our understanding of the nuclear reactions that occur in the cores of massive, supernova-prone stars. Another possibility is that the star did not die alone -- a companion star in a binary system may have influenced the life and unusual death of the progenitor of SN 2014C. This second theory fits with the observation that about seven out of 10 massive stars have companions.
The study suggests that astronomers should pay attention to the lives of massive stars in the centuries before they explode. Astronomers will also continue monitoring the aftermath of this perplexing supernova.
"The notion that a star could expel such a huge amount of matter in a brief interval is completely new," says Fiona Harrison, NuSTAR principal investigator based at Caltech in Pasadena. "It is challenging our basic ideas about how massive stars evolve, and eventually explode, distributing the chemical elements basic for life."
NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASAs Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTARs mission operations center is at UC Berkeley, and the official data archive is at NASAs High Energy Astrophysics Science Archive Research Center. ASI provides the missions ground station and a mirror archive. JPL is managed by Caltech for NASA.
Post subject: Vast Magnetic Field Linking the Milky Way to Its Satellite G
Posted: Sat Apr 17, 2021 3:37 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Vast Magnetic Field Linking the Milky Way to Its Satellite Galaxies --"Oberved for 1st Time"
For the first time, astronomers have detected a magnetic field associated with the Magellanic Bridge, the filament of gas stretching 75 thousand light-years between the Milky Way Galaxys nearest galactic neighbors: the Large and Small Magellanic Clouds (LMC and SMC, respectively). "There were hints that this magnetic field might exist, but no one had observed it until now," says Jane Kaczmarek, at the University of Sydney, and direct author of the paper describing the finding.
"Not only are entire galaxies magnetic, but the faint slight threads joining galaxies are magnetic, too,"said Bryan Gaensler, Director of the Dunlap Institute for Astronomy & Astrophysics, University of Toronto, and a co-author on the paper. "Everywhere we look in the sky, we find magnetism."
"In general, we dont know how such vast magnetic fields are generated, nor how these large-scale magnetic fields affect galaxy formation and evolution," says Kaczmarek. "The LMC and SMC are our nearest neighbours, so understanding how they evolve may help us understand how our Milky Way Galaxy will evolve. Understanding the role that magnetic fields play in the evolution of galaxies and their environment is a basic question in astronomy that remains to be answered."
Visible in the southern night sky, the LMC and SMC are dwarf galaxies that orbit our home galaxy and lie at a distance of 160 and 200 thousand light-years from Earth respectively,
Such cosmic magnetic fields can only be detected indirectly, and this detection was made by observing the radio signals from hundreds of very distant galaxies that lie beyond the LMC and SMC. The observations were made with the Australia Telescope Compact Array radio telescope at the Paul Wild Observatory in New South Wales, Australia. This visible light mosaic below shows the LMC and SMC in context with the plane of our own galaxy, the Milky Way. (Axel Mellinger, Central Michigan University).
"The radio emission from the distant galaxies served as background flashlights that shine through the Bridge," says Kaczmarek. "Its magnetic field then changes the polarization of the radio signal. How the polarized light is changed tells us about the intervening magnetic field."
A radio signal, like a light wave, oscillates or vibrates in a single direction or plane; for example, waves on the surface of a pond move up and down. When a radio signal passes through a magnetic field, the plane is rotated. This phenomenon is known as Faraday Rotation and it allows astronomers to measure the strength and the polarityor directionof the field.
The observation of the magnetic field, which is one millionth the strength of the Earths, may provide insight into whether it was generated from within the Bridge after the structure formed, or was "ripped" from the dwarf galaxies when they interacted and formed the structure.
The paper, one of a growing number of new results that are building a map of the Universes magnetism, appeared in the Monthly Notices of the Royal Astronomical Society.
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