- Infectious particles of the SARS-CoV-2 virus isolated from hospital air News-Medical.Net
- Effectiveness of an inactivated SARS-CoV-2 vaccine in children and adolescents: a large-scale observational study The Lancet
- Comparison of SARS-CoV-2 whole genome sequencing using tiled amplicon enrichment and bait hybridization | Scientific Reports Nature.com
- Protein OCLN found to play crucial role in SARS-CoV-2 cell-to-cell transmission News-Medical.Net
- SARS-CoV-2 incubation period across variants of concern, individual factors, and circumstances of infection in France: a case series analysis from the ComCor study The Lancet
- View Full Coverage on Google News
Tag Archives: particles
Neutrons: Facts about the influential subatomic particles
Neutrons are tiny subatomic particles that — along with protons — form the nucleus of an atom.
While the number of protons defines what element an atom is, the number of neutrons in the nucleus can vary, resulting in different isotopes of an element. For example, ordinary hydrogen contains one proton and no neutrons, but the isotopes of hydrogen, deuterium and tritium, have one and two neutrons, respectively, alongside the proton.
Neutrons are composite particles made up of three smaller, elementary particles called quarks, held together by the Strong Force. Specifically, a neutron contains one ‘up’ and two ‘down’ quarks. Particles made from three quarks are called baryons, and hence baryons contribute to all the baryonic ‘visible’ matter in the universe.
Related: What is the theory of everything?
Who discovered neutrons?
After Ernest Rutherford (with help from Ernest Marsden and Hans Geiger‘s gold-leaf experiment) had discovered in 1911 that atoms have a nucleus, and then nine years later discovered that atomic nuclei are made, at least in part, by protons, the discovery of the neutron in 1932 by James Chadwick naturally followed.
The idea that there must be something else in an atom’s nucleus came from the fact that the number of protons didn’t match an atom’s atomic weight. For example, an oxygen atom contains 8 protons, but has an atomic weight of 16, suggesting that it contains 8 other particles. However, these mystery particles would have to be electrically neutral, since atoms normally have no overall electric charge (the negative charge of the electrons cancels out the positive charge of the protons).
At the time, various scientists were experimenting with alpha particles, which are another name for helium nuclei, bombarding a material made from the element beryllium with an alpha particle stream. When the alpha particles impacted beryllium atoms, they produced mysterious particles that appeared to originate from within the beryllium atoms. Chadwick took these experiments one step further and saw that when the mystery particles hit a target made of paraffin wax, they would knock loose protons at high energy. In order to do this, Chadwick reasoned, the mystery particles must have more or less the same mass as a proton. Chadwick proclaimed this mystery particle to be the neutron, and in 1935 he won a Nobel Prize for his discovery.
Neutrons: Mass and charge
As their name suggests, neutrons are electrically neutral, so they have no charge. Their mass is 1.008 times the mass of the proton — in other words, it’s approximately 0.1% heavier.
Neutrons don’t like to exist on their own outside the nucleus. The binding energy of the Strong Force between them and protons in the nucleus keeps them stable, but when out on their own they undergo beta decay after about 15 minutes, transforming into a proton, an electron and an antineutrino.
Albert Einstein, in his famous equation E = mc2, said that mass and energy are equivalent. Although the mass of a neutron and a proton are only slightly different, this slight difference means that a neutron has more mass, and therefore more energy, than a proton and an electron combined. That’s why, when a neutron decays, it produces a proton and an electron.
Isotopes and radioactivity
An isotope is a variation of an element that has more neutrons. For instance, at the top of this article, we gave the example of the hydrogen isotopes deuterium and tritium, which have 1 and 2 extra neutrons, respectively. Some isotopes are stable, deuterium for instance. Others are unstable and inevitably undergo radioactive decay. Tritium is unstable — it has a half-life of about 12 years (a half-life is the time it takes on average for half of a given amount of an isotope like tritium to decay), but other isotopes decay far more rapidly, in a matter of minutes, second or even fractions of a second.
Neutrons are also essential tools in nuclear reactions, in particular when inducing a chain reaction. Neutrons absorbed by atomic nuclei create unstable isotopes that then undergo nuclear fission (splitting into two smaller daughter nuclei of other elements). For example, when uranium-235 absorbs an extra neutron, it becomes unstable and breaks apart, releasing energy in the process.
Neutrons are also instrumental in the creation of heavy elements in massive stars, through a mechanism known as the r-process, with “r” meaning “rapid”. This process was first detailed in the famous, Nobel Prize-winning B2FH paper by Margaret and Geoffrey Burbidge, William Fowler and Fred Hoyle that described the origins of the elements through stellar nucleosynthesis — the forging of elements by stars.
(opens in new tab)
Stars like the sun can produce elements of oxygen, nitrogen and carbon through nuclear fusion reactions. More massive stars can keep going and create shells of increasingly heavier elements all the way down to iron-56 in the star’s core. At this point, the reactions require more energy to be put into them to fuse elements heavier than iron than what is actually produced by those reactions, so those reactions cease, energy production grinds to a halt and the core of the star collapses, instigating a supernova. And it’s in the incredibly violent blast of a supernova that conditions can become extreme enough to liberate lots of free neutrons in a short space of time.
In the supernova blast, atomic nuclei are then able to sweep up all these free neutrons before they all decay (this is why it’s described as rapid), to instigate r-process nucleosynthesis. Once the nuclei are full of neutrons they turn unstable and undergo beta decay, transforming those extra neutrons into protons. The addition of these protons changes the type of element that a nucleus is, hence it’s a way of creating new, heavy elements such as gold, platinum and other precious metals. The gold in your jewelry was made billions of years ago by rapid neutron capture in a supernova!
Neutron stars
(opens in new tab)
As we have seen, only in the most extreme conditions can neutrons survive outside of atomic nuclei, and there are very few places in the universe more extreme than neutron stars. As their name suggests, these are objects made almost entirely of neutrons.
Neutron stars are what is left of the core of a star after it has undergone core collapse and exploded as a supernova. The explosion may have carried away the outer layers of the star, but the contracting core remains intact.
With no nuclear reactions to generate energy to counteract gravity, the mass of the core is so great that it undergoes a catastrophic gravitational collapse in which the gravitational pressure is great enough that protons and electrons are able to overcome the electrostatic force between them and smush together, merging to form neutrons in a kind of reverse beta decay. Almost all the atoms in the core turn into neutrons, hence why we call the result a neutron star. They are small, just 6-12 miles (10-20 km) across, yet they pack in the entire mass of the dead star’s core.
The most massive neutron star yet found has a mass 2.35 times greater than our sun, all crammed into a tiny volume. If you could scoop a spoonful’s worth of material from the surface of a neutron star, that spoonful would weigh as much as a mountain on Earth!
Binary neutron star mergers, which are detectable as kilonovae and via their gravitational waves, are also sites of copious r-process nucleosynthesis. The kilonova of two merging binary stars that released the gravitational-wave burst GW 170817 produced 16,000 times the mass of Earth in the form of r-process heavy elements, including ten Earth masses’ worth of gold and platinum, which is extraordinary!
Follow Keith Cooper on Twitter @21stCenturySETI. Follow us on Twitter @Spacedotcom and on Facebook.
Additional resources
Learn more about neutrons with the U.S. Department of Energy (opens in new tab). Explore how neutrons are used in experiments that study condensed matter with the UK Science Technology Facilities Council (opens in new tab). Read the famous B2FH paper (opens in new tab) about the creation of elements inside stars with the help of neutron capture.
Bibliography
Particle Physics, by Brian R. Martin (2011, One-World Publications) (opens in new tab)
The Cambridge Encyclopedia of Stars, by James R. Kaler (2006, Cambridge University Press) (opens in new tab):
Collins Internet-Linked Dictionary of Physics (2007, Collins) (opens in new tab)
This month in physics history. American Physical Society Sites, APS News, Volume 16, number 5. Accessed Dec. 1, 2022, from https://www.aps.org/publications/apsnews/200705/physicshistory.cfm (opens in new tab)
Neutron decay. Science Direct. Accessed Dec. 1, 2022, from https://www.sciencedirect.com/topics/physics-and-astronomy/neutron-decay (opens in new tab)
Ghost Particles Crashing Into Antarctica Could Change Astronomy Forever
About 47 million light-years from where you’re sitting, the center of a black-hole-laden galaxy named NGC 1068 is spitting out streams of enigmatic particles. These “neutrinos” are also known as the elusive “ghost particles” that haunt our universe but leave little trace of their existence.
Immediately after coming into being, bundles of these invisible bits plunge across the cosmic expanse. They whisk by bright stars we can see and zip past pockets of space teeming with marvels we’re yet to discover. They fly and fly and fly until, occasionally, they crash into a detector deep below the surface of the Earth.
The neutrinos’ journey is seamless. But scientists patiently wait for them to arrive.
Nestled into about 1 billion tons of ice, more than 2 kilometers (1.24 miles) beneath Antarctica, lies the IceCube Neutrino Observatory. A neutrino hunter, you might call it. When any neutrinos transfer their party to the frigid continent, IceCube stands ready.
In a paper published Friday in the journal Science, the international team behind this ambitious experiment confirmed it has found evidence of 79 “high-energy neutrino emissions” coming from around where NGC 1068 is located, opening the door for novel — and endlessly fascinating — types of physics. “Neutrino astronomy,” scientists call it.
It’d be a branch of astronomy that can do what existing branches simply cannot.
Front view of the IceCube Lab at twilight, with a starry sky showing a glimpse of the Milky Way overhead and sunlight lingering on the horizon.
Martin Wolf, IceCube/NSF
Before today, physicists had only shown neutrinos coming from either the sun; our planet’s atmosphere; a chemical mechanism called radioactive decay; supernovas; and — thanks to IceCube’s first breakthrough in 2017 — a blazar, or voracious supermassive black hole pointed directly toward Earth. A void dubbed TXS 0506+056.
With this newfound neutrino source, we’re entering a new era of the particle’s story. In fact, according to the research team, it’s likely neutrinos stemming from NGC 1068 have up to millions, billions, maybe even trillions the amount of energy held by neutrinos rooted in the sun or supernovas. Those are jaw-dropping figures because, in general, such ghostly bits are so powerful, yet evasive, that every second, trillions upon trillions of neutrinos move right through your body. You just can’t tell.
And if you wanted to stop a neutrino in its tracks, you’d need to fight it with a block of lead one light-year-wide — though even then, there’d be a fractional chance of success. Thus, harnessing these particles, NCG 1068’s version or not, could allow us to penetrate areas of the cosmos that’d usually lie out of reach.
Now what?
Not only is this moment massive because it gives us more proof of a strange particle that wasn’t even announced to exist until 1956, but also because neutrinos are like keys to our universe’s backstage.
They hold the capacity to reveal phenomena and solve puzzles we’re unable to address by any other means, which is the primary reason scientists are trying to develop neutrino astronomy in the first place.
“The universe has multiple ways of communicating with us,” Denise Caldwell of the National Science Foundation and a member of the IceCube team, told reporters on Thursday. “Electromagnetic radiation, which we see as light from stars, gravitational waves that shake the fabric of space — and elementary particles, such as protons, neutrons and electrons spewed out by localized sources.
“One of these elementary particles has been neutrinos that permeate the universe, but unfortunately, neutrinos are very difficult to detect.”
In fact, even the galaxy NGC 1068 and its gargantuan black hole are typically obscured by a thick veil of dust and gas, making them hard to parse with standard optical telescopes and equipment — despite years of scientists trying to pierce its curtain. NASA’s James Webb Space Telescope could have a leg up in this case due to its infrared eyes, but neutrinos may be an even better way in.
Expected to be generated behind such opaque screens filtering our universe, these particles can carry cosmic information from behind those screens, zoom across great distances while interacting with essentially no other matter, and deliver pristine, untouched information to humanity about elusive corners of outer space.
“We are very lucky, in a sense, because we can access an amazing understanding of this object,” Elisa Resconi, of the Technical University of Munich and IceCube team member, said of NGC 1068.
In this artistic rendering, based on a real image of the IceCube Lab at the South Pole, a distant source emits neutrinos that are detected below the ice by IceCube sensors, called DOMs.
IceCube/NSF
It’s also notable that there are many (many) more galaxies similar to NGC 1068 — categorized as Seyfert galaxies — than there are blazars similar to TXS 0506+056. This means IceCube’s latest discovery is, arguably, a larger step forward for neutrino astronomers than the observatory’s seminal one.
Perhaps the bulk of neutrinos diffusing throughout the universe are rooted in NGC 1068 doppelgangers. But in the grand scheme of things, there’s far more to the merit of neutrinos than just their sources.
These ghosts, as Justin Vandenbroucke of the University of Wisconsin-Madison and an IceCube team member put it, are fit to solve two major mysteries in astronomy.
First off, a wealth of galaxies in our universe boast gravitationally monstrous voids at their centers, black holes reaching masses millions to billions of times greater than our sun’s. And these black holes, when active, blast jets of light from their guts — emitting enough illumination to outshine every single star in the galaxy itself. “We don’t understand how that happens,” Vandenbrouke said simply. Neutrinos could provide a way to study the regions around black holes.
Second is the general, yet persistent, conundrum of cosmic rays.
We don’t really know where cosmic rays come from either, but these strings of particles reach energies to and beyond millions of times higher than we can reach here on Earth with human-constructed particle accelerators like the one at CERN.
“We think neutrinos have some role to play,” Vandenbroucke said. “Something that can help us answer these two mysteries of black holes powering very bright galaxies and of the origins of cosmic rays.”
A decade to catch a handful
To be clear, IceCube doesn’t exactly trap neutrinos.
Basically, this observatory tells us every time a neutrino happens to interact with the ice shrouding it. “Neutrinos hardly interact with matter,” Vandenbrouke emphasized. “But they do interact sometimes.”
As millions of neutrinos shoot into the icy region where IceCube is set up, at least one tends to bump into an atom of ice, which then shatters and produces a flash of light. IceCube sensors capture that flash and send the signal up to the surface, notifications that are then analyzed by hundreds of scientists.
A rendering of the IceCube detector shows the interaction of a neutrino with a molecule of ice.
IceCube Collaboration/NSF
Ten years of light-flash-data allowed the team to pretty much map out where every neutrino seems to be coming from in the sky. It soon became clear there was a dense region of neutrino emissions located right where galaxy NGC 1068 is stationed.
But even with such evidence, Resconi said the team knew “it’s not the time to open the champagne, because we still have one fundamental question to answer. How many times did this alignment happen just by chance? How can we be sure neutrinos are actually coming from such an object?”
A sky map of the scan for point sources in the Northern Hemisphere, showing where neutrinos seem to be coming from across the universe. The circle of NGC 1068 also coincides with the overall hottest spot in the northern sky.
IceCube Collaboration
So, to make matters as concrete as possible, and really, truly prove this galaxy is spitting out ghosts, “we generated 500 million times the same experiment,” Resconi said.
Upon which, I can only imagine, a bottle of Veuve was popped at last. Though the hunt isn’t over.
“We are only beginning to scratch the surface as far as finding new sources of neutrinos,” Ignacio Taboada of the Georgia Institute of Technology and IceCube team member said. “There must be many other sources far deeper than NGC 1068, hiding somewhere to be found.”
Ghost Particles Crashing Into Antarctica Reveal Unseen Heart of Nearby Galaxy
About 47 million light-years from where you’re sitting, the center of a black-hole-laden galaxy named NGC 1068 is spitting out streams of enigmatic particles. These “neutrinos,” otherwise known as the notoriously elusive “ghost particles,” haunt our universe but leave little trace of their existence.
Immediately after coming into being, bundles of these invisible bits plunge across the cosmic expanse. They whisk by bright stars we can see and zip past pockets of space teeming with marvels we’re yet to discover. They fly and fly and fly until, occasionally, they crash into a detector deep below the surface of the Earth.
The neutrinos’ journey is seamless. But scientists patiently wait for them to arrive.
Nestled into about 1 billion tons of ice, more than 2 kilometers (1.24 miles) beneath Antarctica, lies the IceCube Neutrino Observatory. A neutrino hunter, you might call it. When any neutrinos transfer their party to the frigid continent, IceCube stands ready.
In a paper published Friday in the journal Science, the international team behind this ambitious experiment confirmed it has found evidence of 79 “high-energy neutrino emissions” coming from around where NGC 1068 is located, opening the door for novel — and endlessly fascinating — types of physics. “Neutrino astronomy,” scientists call it.
It’d be a branch of astronomy that can do what existing branches simply cannot.
Front view of the IceCube Lab at twilight, with a starry sky showing a glimpse of the Milky Way overhead and sunlight lingering on the horizon.
Martin Wolf, IceCube/NSF
Before today, physicists had only shown neutrinos coming from either the sun; our planet’s atmosphere; a chemical mechanism called radioactive decay; supernovas; and — thanks to IceCube’s first breakthrough in 2017 — a blazar, or voracious supermassive black hole pointed directly toward Earth. A void dubbed TXS 0506+056.
With this newfound neutrino source, we’re entering a new era of the particle’s story. In fact, according to the research team, it’s likely neutrinos stemming from NGC 1068 have up to millions, billions, maybe even trillions the amount of energy held by neutrinos rooted in the sun or supernovas. Those are jaw-dropping figures because, in general, such ghostly bits are so powerful, yet evasive, that every second, trillions upon trillions of neutrinos move right through your body. You just can’t tell.
And if you wanted to stop a neutrino in its tracks, you’d need to fight it with a block of lead one light-year-wide — though even then, there’d be a fractional chance of success. Thus, harnessing these particles, NCG 1068’s version or not, could allow us to penetrate areas of the cosmos that’d usually lie out of reach.
Now what?
Not only is this moment massive because it gives us more proof of a strange particle that wasn’t even announced to exist until 1956, but also because neutrinos are like keys to our universe’s backstage.
They hold the capacity to reveal phenomena and solve puzzles we’re unable to address by any other means, which is the primary reason scientists are trying to develop neutrino astronomy in the first place.
“The universe has multiple ways of communicating with us,” Denise Caldwell of the National Science Foundation and a member of the IceCube team, told reporters on Thursday. “Electromagnetic radiation, which we see as light from stars, gravitational waves that shake the fabric of space — and elementary particles, such as protons, neutrons and electrons spewed out by localized sources.
“One of these elementary particles has been neutrinos that permeate the universe, but unfortunately, neutrinos are very difficult to detect.”
In fact, even the galaxy NGC 1068 and its gargantuan black hole are typically obscured by a thick veil of dust and gas, making them hard to parse with standard optical telescopes and equipment — despite years of scientists trying to pierce its curtain. NASA’s James Webb Space Telescope could have a leg up in this case due to its infrared eyes, but neutrinos may be an even better way in.
Expected to be generated behind such opaque screens filtering our universe, these particles can carry cosmic information from behind those screens, zoom across great distances while interacting with essentially no other matter, and deliver pristine, untouched information to humanity about elusive corners of outer space.
“We are very lucky, in a sense, because we can access an amazing understanding of this object,” Elisa Resconi, of the Technical University of Munich and IceCube team member, said of NGC 1068.
In this artistic rendering, based on a real image of the IceCube Lab at the South Pole, a distant source emits neutrinos that are detected below the ice by IceCube sensors, called DOMs.
IceCube/NSF
It’s also notable that there are many (many) more galaxies similar to NGC 1068 — categorized as Seyfert galaxies — than there are blazars similar to TXS 0506+056. This means IceCube’s latest discovery is, arguably, a larger step forward for neutrino astronomers than the observatory’s seminal one.
Perhaps the bulk of neutrinos diffusing throughout the universe are rooted in NGC 1068 doppelgangers. But in the grand scheme of things, there’s far more to the merit of neutrinos than just their sources.
These ghosts, as Justin Vandenbroucke of the University of Wisconsin-Madison and an IceCube team member put it, are fit to solve two major mysteries in astronomy.
First off, a wealth of galaxies in our universe boast gravitationally monstrous voids at their centers, black holes reaching masses millions to billions of times greater than our sun’s. And these black holes, when active, blast jets of light from their guts — emitting enough illumination to outshine every single star in the galaxy itself. “We don’t understand how that happens,” Vandenbrouke said simply. Neutrinos could provide a way to study the regions around black holes.
Second is the general, yet persistent, conundrum of cosmic rays.
We don’t really know where cosmic rays come from either, but these strings of particles reach energies to and beyond millions of times higher than we can reach here on Earth with human-constructed particle accelerators like the one at CERN.
“We think neutrinos have some role to play,” Vandenbroucke said. “Something that can help us answer these two mysteries of black holes powering very bright galaxies and of the origins of cosmic rays.”
A decade to catch a handful
To be clear, IceCube doesn’t exactly trap neutrinos.
Basically, this observatory tells us every time a neutrino happens to interact with the ice shrouding it. “Neutrinos hardly interact with matter,” Vandenbrouke emphasized. “But they do interact sometimes.”
As millions of neutrinos shoot into the icy region where IceCube is set up, at least one tends to bump into an atom of ice, which then shatters and produces a flash of light. IceCube sensors capture that flash and send the signal up to the surface, notifications that are then analyzed by hundreds of scientists.
A rendering of the IceCube detector shows the interaction of a neutrino with a molecule of ice.
IceCube Collaboration/NSF
Ten years of light-flash-data allowed the team to pretty much map out where every neutrino seems to be coming from in the sky. It soon became clear there was a dense region of neutrino emissions located right where galaxy NGC 1068 is stationed.
But even with such evidence, Resconi said the team knew “it’s not the time to open the champagne, because we still have one fundamental question to answer. How many times did this alignment happen just by chance? How can we be sure neutrinos are actually coming from such an object?”
A sky map of the scan for point sources in the Northern Hemisphere, showing where neutrinos seem to be coming from across the universe. The circle of NGC 1068 also coincides with the overall hottest spot in the northern sky.
IceCube Collaboration
So, to make matters as concrete as possible, and really, truly prove this galaxy is spitting out ghosts, “we generated 500 million times the same experiment,” Resconi said.
Upon which, I can only imagine, a bottle of Veuve was popped at last. Though the hunt isn’t over.
“We are only beginning to scratch the surface as far as finding new sources of neutrinos,” Ignacio Taboada of the Georgia Institute of Technology and IceCube team member said. “There must be many other sources far deeper than NGC 1068, hiding somewhere to be found.”
Ghostly Neutrino Particles Provide a Peek at Heart of Nearby Galaxy
A gigantic observatory buried in the Antarctic ice has helped scientists trace elusive particles called neutrinos back to their origins at the heart of a nearby galaxy—offering a new way to study a supermassive black hole shrouded from view.
According to a new study published Thursday in the journal Science, neutrinos are accelerating toward Earth from the center of a spiral-shaped galaxy known as Messier 77, which is about 47 million light years from Earth. There, a matter- and radiation-dense region surrounds a black hole many millions times as massive as our sun.
The celestial heart of Messier 77 is situated in such a way that the dust and gas circulating around the black hole obscure the object when it is viewed from Earth using typical methods such as telescopes that rely on optical light.
“We’re seeing the galaxy a little bit sideways, and because we’re looking at it sideways, the black hole is hiding behind material that is orbiting near it,” said Ignacio Taboada, a professor of physics at the Georgia Institute of Technology and spokesman for the international collaboration that conducted the research.
But neutrinos—the most abundant, energetic particles in the universe—pass through such gas and dust unaffected because they rarely interact with anything, including magnetic fields, matter or gravity. This ghostly aspect offers scientists an unprecedented means of probing processes happening around the previously hidden black hole, including how it accelerates the superhot, charged gas and matter in the vicinity, the researchers said.
“Neutrinos are a different way to look at the universe. And every time that you look at the universe in a new way, you learn something that you could not have learned with the old methods,” said Dr. Taboada.
One of the more than 5,000 sensors that collect data at the IceCube Neutrino Observatory in Antarctica.
Photo:
Mark Krasberg, IceCube/NSF
Neutrinos preserve the information that was imprinted when they were generated at their sources, including their energies, according to Hans Niederhausen, a postdoctoral associate at Michigan State University who participated in the research. That same energy is brought to Earth along with the neutrinos.
Now that they know where certain neutrinos came from, the researchers are studying them to better understand where within Messier 77 the interactions happen that create and accelerate these particles—and the behavior and nature of the black hole itself, Dr. Niederhausen said.
They also plan to comb the cosmos for other neutrinos from galaxies with active supermassive black holes similar to Messier 77. This galaxy “gives us a very good idea where to look next,” he added.
The neutrino-detecting telescope used in the study, known as the IceCube Neutrino Observatory, is buried in a billion tons of ice around the U.S. Amundsen-Scott South Pole Station. As neutrinos pass through the Earth, they occasionally collide with atoms in the ice. The observatory’s more than 5,000 basketball-sized sensors detect byproducts of those rare collisions and send that data to computers at the surface.
The $279 million observatory, mainly funded by the National Science Foundation, was completed in 2011 and detects roughly 100,000 neutrinos a year. Nearly all those neutrinos are created by processes in our atmosphere, but a few hundred or so neutrinos detected annually originate from outside our solar system—known as astrophysical neutrinos.
The lab that houses the computers that collect data from sensors under the Antarctic ice.
Photo:
Moreno Baricevic, IceCube/NSF
Because neutrinos penetrate matter and pass through unaffected, they unerringly travel in a straight line from their point of creation. So, by plotting an astrophysical neutrino’s direction of travel through the ice, researchers can reconstruct its path back across the universe to its source.
Nearly 400 scientists at more than 50 institutions make up the international IceCube collaboration, which analyzed data collected by the observatory between 2011 and 2020 to identify 79 neutrinos that originated from Messier 77.
That IceCube is finding individual objects that are the sources of astrophysical neutrinos is “absolutely amazing,” said Dr. Yoshi Uchida, a professor of physics at Imperial College London who wasn’t involved in the study. “After running for 10 years, it’s turning the observation of neutrinos into another source of information.”
Dr. Taboada said he thinks IceCube will continue to get more neutrinos originating from this galaxy. Those future detections could not only help parse out additional details about Messier 77’s supermassive black hole, but could help answer the “oldest question in astronomy,” according to Francis Halzen, a University of Wisconsin-Madison physicist and principal investigator of IceCube.
Scientists have known about the existence of cosmic rays—streams of high-energy protons and atomic nuclei which travel at near-light speeds and create electromagnetic radiation and showers of subatomic particles when they hit Earth’s atmosphere—for more than a century. But the origin of these rays, and what mechanism speeds them up and sends them in our direction, remains elusive.
“Something in the universe gave them a ginormous kick to make them go that fast,” Dr. Niederhausen said of cosmic rays.
Neutrinos are a byproduct of those cosmic rays’ interactions with the matter and radiation surrounding high-energy objects like supermassive black holes, so Drs. Halzen and Taboada said tracing the ghostly particles back to their beginnings could help solve the origins of cosmic rays, too.
Write to Aylin Woodward at aylin.woodward@wsj.com
Copyright ©2022 Dow Jones & Company, Inc. All Rights Reserved. 87990cbe856818d5eddac44c7b1cdeb8
Surprise! Black holes can behave like quantum particles
Black holes have properties characteristic of quantum particles, a new study reveals, suggesting that the puzzling cosmic objects can be at the same time small and big, heavy and light, or dead and alive, just like the legendary Schrödinger’s cat.
The new study, based on computer modeling, aimed to find the elusive connection between the mind-boggling time-warping physics of supermassive objects such as black holes and the principles guiding the behavior of the tiniest subatomic particles.
The study team developed a mathematical framework that placed a simulated quantum particle just outside a giant simulated black hole. The simulation revealed that the black hole showed signs of quantum superposition, the ability to exist in multiple states at once — in this case, to be at the same time both massive and not massive at all.
Related: Do we live in a quantum world?
“We wanted to see whether [black holes] could have wildly different masses at the same time, and it turns out they do,” study lead author Joshua Foo, a PhD researcher in theoretical physics at the University of Queensland, said in a statement (opens in new tab). “Until now, we haven’t deeply investigated whether black holes display some of the weird and wonderful behaviors of quantum physics.”
The best known example of quantum superposition is the legendary Schrödinger’s cat, a thought experiment designed by early 20th century physicist Erwin Schrödinger to demonstrate some of the key issues with quantum physics. According to quantum theories, subatomic particles exist in multiple states simultaneously until they interact with the external world. This interaction, which could be the simple act of being measured or observed, throws the particle into one of the possible states.
Schrödinger, who won the Nobel Prize in Physics in 1933, intended the experiment to demonstrate the absurdity of quantum theory, as it would suggest that a cat locked in a box can be at the same time dead and alive based on the random behavior of atoms, until an observer breaks the superposition.
However, as it turned out, while a cat in a box could be dead regardless of the observer’s actions, a quantum particle may indeed exist in a double state. And the new study indicates that a black hole does as well.
American and Israeli theoretical physicist Jacob Bekenstein was the first to postulate that black holes may have quantum properties. Since a black hole is defined by its mass, its quantum superposition must mean that this odd gravitational gateway can have multiple masses that fall within certain ratios.
“Our modeling showed that these superposed masses were, in fact, in certain determined bands or ratios — as predicted by Bekenstein,” study co-author Magdalena Zych, a physicist at the University of Queensland and a co-supervisor of the research, said in the statement. “We didn’t assume any such pattern going in, so the fact we found this evidence was quite surprising.”
Not that we are any closer to understanding what is going on inside black holes. But whatever that is, it is probably even more fantastic than we could imagine.
The new study (opens in new tab) was published online in the journal Physical Review Letters on Friday (Oct. 28).
Follow Tereza Pultarova on Twitter @TerezaPultarova (opens in new tab). Follow us on Twitter @Spacedotcom (opens in new tab) and on Facebook (opens in new tab).
Purified Sand Particles Have Anti-Obesity Effects, Scientists Confirm : ScienceAlert
Porous particles of silica made from purified sand could one day play a role in attempts to lose weight.
Past clinical trials have already produced promising results, but the actual weight-lowering mechanism behind the potential treatment has been poorly understood.
To sift out the key variables, researchers have now tested a range of silica sizes and shapes in a simulation of the human gut after a heavy meal.
The results support the idea that porous silica can “impede the digestive processes” that are usually triggered by enzymes breaking down fat, cholesterol, starches, and sugars in the stomach and intestines.
What’s more, the size of administered nanoparticles seems to determine how much digestive activity is inhibited.
The authors acknowledge that their model is much too simple to perfectly mimic the complexity of the human gut during digestion, but given the ethics surrounding human clinical trials, gut simulations and animal models are closer than researchers might otherwise get.
Unlike other human gut models, this new one accounts for both fat digestion and carbohydrate digestion. The authors also analzyed the degree to which organic matter might be absorbed within the gastrointestinal tract.
It’s possible that porous silica triggers a reduction of weight gain in other ways, too, but the new findings provide additional research with a more solid place to start.
In 2014, researchers found mice on high fat diets put on significantly less weight when fed nanoparticles of porous silica (MSPs). Their total body fat percentage was also reduced. Still, that effect seemed to be based on the relative size of the silica particles used. Larger particles were ultimately more effective.
Follow-up studies on mice supported these results. The right size and shape of porous silica particles seemed to determine the power of mouse digestion in the small intestine.
In 2020, the first clinical data on 10 healthy humans with obesity demonstrated that MSPs can reduce blood glucose levels and blood cholesterol levels, both of which are known risk factors for metabolic and cardiovascular complications.
Even better, the treatment did not trigger any abdominal discomfort or changes to bowel habits, which can’t be said of current medicines for weight gain like Orlistat.
The current research elaborates on these promising findings by comparing an array of 13 porous silica samples of various widths, absorption potentials, shapes, sizes, and surface chemistries.
These samples were each introduced to a human gastrointestinal model that simulated a fed state after a high-carbohydrate, high-fat meal. The model allowed for half an hour of gastric digestion and an hour of intestinal digestion and absorption.
Fat digestion was monitored by titrating fatty acids from what was absorbed, while starch digestion was monitored by measuring the concentration of sugars absorbed.
The authors say the ideal silica samples were silica microparticles with pore widths between 6 and 10 nanometers. These sizes seemed to inhibit the enzymes examined best.
The pores don’t just appear to trap enzymes, either. It’s more complicated than that, researchers think.
Some pores which were the optimal size for inhibiting starch digestion, for instance, were too large to optimally trap enzymes associated with fat digestion.
The porous sand particles also seemed to absorb digested and undigested nutrients from the gastrointestinal tract before they could pass into the system’s bloodstream.
This could be another way in which the particles counter the input of calories.
Those particles with greater surface areas but smaller pores unable to impact digestive enzymes actually absorbed the most organic matter in models.
Further research on animal models will be needed to replicate these results. Maybe after that, the proposed mechanism can be validated in human clinical trials.
The study was published in Pharmaceutics.
Revealed: Babies have air pollution particles in their lungs while they’re still in the WOMB
Revealed: Babies have air pollution particles in their lungs while they’re still in the WOMB
- Air pollution particles can reach babies in the womb, a landmark study suggests
- Pollutants from traffic fumes can cross the placenta and get into baby’s organs
- Experts say findings are ‘concerning’ as organ development occurs in the uterus
Unborn babies have air pollution particles in their developing lungs and other vital organs as early as the first trimester, a landmark study has found.
Pollutants from traffic fumes can pass through the mother’s bloodstream, into the placenta through to the baby’s developing organs within the first 12 weeks.
Experts believe it could mean pregnant women living in the most polluted parts of the country are at greater risk of stillbirth and babies born with health problems.
Scientists at the University of Aberdeen, UK, and Hasselt University, Belgium, studied air pollution nanoparticles, called black carbon — or soot particles — to determine if they could reach the foetus.
For the first time, they discovered evidence the pollutants crossed into the developing organs including the liver, lungs, and brain.
They found dangerous nanoparticles — from exhaust fumes and fossil fuels — crossed the placenta into the foetus in the womb as early as three months into pregnancy.
The more air pollution the mothers were exposed to, the greater the level of black carbon nanoparticles found in the baby, according to the findings published in Lancet Planetary Health.
Pollutants from traffic fumes can pass through the mother’s bloodstream, into the placenta through to the baby’s developing organs within the first 12 weeks
Professor Tim Nawrot, of the University of Aberdeen said: ‘We know that exposure to air pollution during pregnancy and infancy has been linked with stillbirth, preterm birth, low weight babies and disturbed brain development, with consequences persisting throughout life.
‘We show in this study that the number of black carbon particles that get into the mother are passed on proportionally to the placenta and into the baby.
‘This means that air quality regulation should recognise this transfer during gestation and act to protect the most susceptible stages of human development.’
Black carbon is a sooty black material released into the air from internal combustion engines, coal-fired power plants, and other sources that burn fossil fuel.
It is a major component of particulate matter, an air pollutant linked to serious health problems including heart disease, respiratory infections and lung cancer.
Previous research into babies found exposure in the womb increased risk of low birth weight and preterm birth.
Black carbon nanoparticles had been found to get into the placenta, but there was no solid evidence that these particles then entered the foetus until now.
The findings also suggest that public health measures are urgently required to minimise pregnant mothers’ exposure to air pollution.
Co-author, Professor Paul Fowler, said: ‘We all worried that if nanoparticles were getting into the foetus, then they might be directly affecting its development in the womb.
‘What we have shown for the first time is that black carbon air pollution nanoparticles not only get into the first and second trimester placenta, but then also find their way into the organs of the developing foetus, including the liver and lungs.
‘What is even more worrying is that these black carbon particles also get into the developing human brain. This means that it is possible for these nanoparticles to directly interact with control systems within human foetal organs and cells.’
These Asteroid Particles May Be Our Most ‘Pristine’ Sample of The Outer Solar System : ScienceAlert
Rubble retrieved from an asteroid in near-Earth solar orbit could be the most ‘pristine’ sample of cosmic rock we’ve had our primate paws on yet.
According to a new, in-depth analysis of the material delivered to Earth from the asteroid Ryugu, the samples of rocks and dust are among the most uncontaminated Solar System materials we’ve ever had the opportunity to study – and their composition suggests that they incorporate chemistry from the outer reaches of the system.
This not only gives us a unique tool for understanding the Solar System and its formation, it gives us new context in which to interpret other space rocks that have been contaminated by coming into contact with Earth.
“Ryugu particles,” wrote a team led by cosmochemist Motoo Ito of the Japan Agency for Marine-Earth Science Technology (JAMSTEC) in Japan, “are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition.”
It has been around 4.6 billion years since the Sun formed, and the Solar System around it. Obviously that’s a very long time, and a lot of things have changed since then; but we do have time capsules that allow us to study the chemistry of the early Solar System in order to understand how it all came together. These are chunks of rock, such as comets and asteroids, that have been drifting about in space more or less unchanged since they formed.
Visiting a rock far from Earth isn’t easy, and collecting and returning samples even less so. Historically, we’ve relied on space rocks coming to us to get our mitts on these time capsules. Meteorites known as carbonaceous chondrites have been the best tool available to probe the composition of the asteroids that may have delivered water to Earth, as the Solar System was still forming.
However, this record is biased by a kind of mineral version of survival of the fittest. Only the strongest chunks of space rock persist through the explosive rigors of atmospheric entry, and even then they become altered and contaminated by the terrestrial environment.
In recent years, venturing out to touch down on asteroids has fallen within our capabilities. In December of 2020, a probe that had been sent to Ryugu by the Japanese Space Agency (JAXA) dropped off an invaluable payload: samples of material collected from the surface of the asteroid, and transported home in sterile containers.
Scientists have been avidly studying the contents ever since, revealing that the asteroid is compositionally very similar to those carbonaceous chondrites, making it what we call a C-type asteroid. It also contains prebiotic molecules – the precursors to biological compounds – and may have once been a comet.
The new analysis delves even deeper. Ito and his colleagues have found that the abundances of heavy hydrogen and nitrogen in the asteroid are consistent with an origin in the outer Solar System; that is, Ryugu started its life much farther from the Sun. This would be consistent with the comet theory, since those icy bodies are visitors from the Solar System’s farther reaches.
Ryugu, the researchers found, also has one glaring difference from carbonaceous chondrites. Missing from the asteroid samples are ferrihydrite (compounds of iron and oxygen) and sulfate (sulfur and oxygen). Since these compounds are found in meteorites, they were thought to be a component of extraterrestrial materials. The lack of them in Ryugu suggests that they could be the result of terrestrial weathering in the meteorites.
This means that future meteorite studies should make allowances for this possibility… and that future asteroid sample return missions will be able to shed more light on the matter.
“In this study we demonstrate that [carbonaceous] meteorites, despite their geochemical importance as proxies of the bulk Solar System composition, are terrestrially contaminated samples,” the researchers wrote in their paper.
“The findings of this study clearly demonstrate the importance of direct sampling of primitive asteroids and the need to transport returned samples in totally inert and sterile conditions. The evidence presented here shows that Ryugu particles are undoubtedly among the most uncontaminated Solar System materials available for laboratory study and ongoing investigations of these precious samples will certainly expand our understanding of early Solar System processes.”
The research has been published in Nature Astronomy.
Origin of ‘ghost particles’ is likely a galactic nuclei fed by supermassive black holes
Origin of ‘ghost particles’ is FOUND: Tiny objects that pass through our bodies and planets undetected are emitted from galactic nuclei fed by supermassive black holes in deep space
- ‘Ghost particles,’ or neutrinos, are particles that come from deep space
- These particles do not have a mass and barely interact with matter
- Scientists believe they originate from galactic nuclei fed by supermassive black holes
- Blazar are known for emitting bright jets and wind and are speculated to also churn out cosmic rays
Deep space ‘ghost particles’ likely originate from galactic nuclei fed by supermassive black holes, according to a new study that could unravel the mystery of these subatomic particles that formed before the universe.
Ghost particles, or neutrinos, have baffled scientists since they were first discovered in 1956 because they have no mass and barely interact with matter.
These tiny particles are without an electrical charge and race through the universe almost entirely unaffected by objects or natural forces, but they are the second most common particles Earth after photons.
The galactic nuclei, known as blazars, are galaxies with colossal black holes at their center and are positioned with their jets pointed directly at Earth.
A team of researchers led by University of Würzburg determined the source of ghost particles by cross-referring data of the particles’ paths and the location of University of Würzburg in the universe.
And they found 10 of 19 of the neutrino hotspots were from blazars.
The mission to unravel the mystery of ghost particles is vital because it will provide a better understanding to how matter evolved from simple particles into complex particles that created everything around us.
Scroll down for video
An artist’s impression of the active galactic nucleus where the ghost-like subatomic particle likely originated
At the center of most galaxies, including our own, sits a supermassive black hole that creates a disk of gas, dust and stellar debris around it.
As material in the disk falls toward the black hole, its gravitational energy can be transformed into light, making the centers of these galaxies very bright and resulting in them being called active galactic nuclei (AGN).
When a galaxy is situated in a way that its jets point toward Earth it is called a blazar and this is the running theory of what produces ghost particles.
This conclusion was determined by researchers who collected data from the IceCube Neutrino Observatory in Antarctica, which is the most sensitive neutrino detector on Earth, from 2008 and 2015.
The study determined ghost particles come from blazar by collecting data of the particles from the IceCube Neutrino Observatory in Antarctica (pictured)
This was then cross-referenced with BZCat, a catalog of more than 3,500 objects that are likely blazars.
The results showed that 10 out of the 19 IceCube hotspots located in the southern sky likely originated from blazars.
Dr Andrea Tramacere, a researcher in the Department of Astronomy at the University of Geneva, said in a statement: ‘The discovery of these high-energy neutrino factories represents a major milestone for astrophysics.
‘It places us a step forward in solving the century-old mystery of the origin of cosmic rays.’
Scientists have been attempting to study the elusive particles since they were first predicted by Wolfgang Pauli in 1931.
Many believe they may hold the key to understanding parts of the universe that remain otherwise hidden from our view, like dark matter and dark energy.
The high-energy neutrino was first detected on September 22, 2017 by the IceCube observatory, a huge facility sunk a mile beneath the South Pole.
Here, a grid of more than 5,000 super-sensitive sensors picked up the characteristic blue ‘Cherenkov’ light emitted as the neutrino interacted with the ice.
The neutrino is thought to have been created by high-energy cosmic rays from the jets interacting with nearby material.
Professor Paul O’Brien, a member of the international team of astronomers from the University of Leicester, said: ‘Neutrinos rarely interact with matter.
‘To detect them at all from the cosmos is amazing, but to have a possible source identified is a triumph.
‘This result will allow us to study the most distant, powerful energy sources in the universe in a completely new way.’