From ARC Centres of Excellence via Science Alert: “We May Soon Know How a Crucial Einstein Principle Works in The Quantum Realm”

From ARC Centres of Excellence

via

Science Alert

(NiPlot/iStock)

20 AUG 2018
MICHELLE STARR

The puzzle of how Einstein’s equivalence principle plays out in the quantum realm has vexed physicists for decades. Now two researchers may have finally figured out the key that will allow us to solve this mystery.

Einstein’s physical theories have held up under pretty much every classical physics test thrown at them. But when you get down to the very smallest scales – the quantum realm – things start behaving a little bit oddly.

The thing is, it’s not really clear how Einstein’s theory of general relativity and quantum mechanics work together. The laws that govern the two realms are incompatible with each other, and attempts to resolve these differences have come up short.

But the equivalence principle – one of the cornerstones of modern physics – is an important part of general relativity. And if it can be resolved within the quantum realm, that may give us a toehold into resolving general relativity and quantum mechanics.

The equivalence principle, in simple terms, means that gravity accelerates all objects equally, as can be observed in the famous feather and hammer experiment conducted by Apollo 15 Commander David Scott on the Moon.

It also means that gravitational mass and inertial mass are equivalent; to put it simply, if you were in a sealed chamber, like an elevator, you would be unable to tell if the force outside the chamber was gravity or acceleration equivalent to gravity. The effect is the same.

“Einstein’s equivalence principle contends that the total inertial and gravitational mass of any objects are equivalent, meaning all bodies fall in the same way when subject to gravity,” explained physicist Magdalena Zych of the ARC Centre of Excellence for Engineered Quantum Systems in Australia.

“Physicists have been debating whether the principle applies to quantum particles, so to translate it to the quantum world we needed to find out how quantum particles interact with gravity.

“We realised that to do this we had to look at the mass.”

According to relativity, mass is held together by energy. But in quantum mechanics, that gets a bit complicated. A quantum particle can have two different energy states, with different numerical values, known as a superposition.

And because it has a superposition of energy states, it also has a superposition of inertial masses.

This means – theoretically, at least – that it should also have a superposition of gravitational masses. But the superposition of quantum particles isn’t accounted for by the equivalence principle.

“We realised that we had to look how particles in such quantum states of the mass behave in order to understand how a quantum particle sees gravity in general,” Zych said.

“Our research found that for quantum particles in quantum superpositions of different masses, the principle implies additional restrictions that are not present for classical particles – this hadn’t been discovered before.”

This discovery allowed the team to re-formulate the equivalence principle to account for the superposition of values in a quantum particle.

The new formulation hasn’t yet been applied experimentally; but, the researchers said, opens a door to experiments that could test the newly discovered restrictions.

And it offers a new framework for testing the equivalence principle in the quantum realm – we can hardly wait.

The team’s research has been published in the journal Nature Physics.

See the full article here .

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The objectives for the ARC Centres of Excellence are to:

undertake highly innovative and potentially transformational research that aims to achieve international standing in the fields of research envisaged and leads to a significant advancement of capabilities and knowledge
link existing Australian research strengths and build critical mass with new capacity for interdisciplinary, collaborative approaches to address the most challenging and significant research problems
develope relationships and build new networks with major national and international centres and research programs to help strengthen research, achieve global competitiveness and gain recognition for Australian research
build Australia’s human capacity in a range of research areas by attracting and retaining, from within Australia and abroad, researchers of high international standing as well as the most promising research students
provide high-quality postgraduate and postdoctoral training environments for the next generation of researchers
offer Australian researchers opportunities to work on large-scale problems over long periods of time
establish Centres that have an impact on the wider community through interaction with higher education institutes, governments, industry and the private and non-profit sector.

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From Columbia University: “Physicists Say There Could Be a Strange Source of ‘Negative Gravity’ All Around Us”

From Columbia University

via

Science Alert

13 AUG 2018
FIONA MACDONALD

(Valerie Loiseleux/iStock)

The macro world as we know it is governed by Newton’s laws of motion and gravity – what goes up, must come down.

But a team of physicists from Columbia University have put forward a theoretical paper that turns this idea on its head. They say there might actually be particles with negative mass – which under gravity, move up, instead of down – and they’re all around us.

According to their paper, it’s not any weird subatomic particle that has these properties, but the particles of sound we hear and produce every day – phonons – that are rebelling against the force of gravity.

So far, so strange, right? After all, sound isn’t even a physical object, so how can the force of gravity have any impact on it?

This paradox is at the heart of the new hypothesis – what if, the researchers say, sound waves actually did carry mass. Negative mass. And that negative mass created its own tiny negative gravitational fields that push them up instead of down.

It sounds pretty wild, but there are three things to keep in mind here.

First, and most importantly, this paper is purely theoretical – that means the researchers have simply put forward a hypothesis and performed some detailed calculations based on how we know the world words, and shown that, in theory, this could be true.

That’s not to say they’ve found any physical evidence sound waves carry negative mass as yet, they’ve simply shown that if it was the case, it wouldn’t break anything else in physics.

The second qualifier is that the paper has only been published on the pre-print site arXiv ahead of peer review. So we need to see some independent verification of these numbers before we get too carried away.

Now keeping those first two in mind, the third thing you need to know is that this idea isn’t actually that insane.

No, really. Bear with us, because there is some logical precedent that’s gone into the hypothesis.

For starters, we know that negative mass particles exist – and they do move against a force in the opposite direction than you’d expect.

Just last year researchers created negative mass fluid in the lab for the first time, and when pushed, it accelerated backwards instead of forwards.

Okay, so negative mass particles might be real. But sound waves aren’t actually particles, are they?

Sound waves move through matter and causes vibrations in the molecules around it, which results in those vibrations being passed on and hitting our eardrums so we can hear.

But although they’re not particles in the traditional sense, sounds waves can be described mathematically as particles, called phonons.

Still, it’s previously been thought that these phonons couldn’t be affected by gravity – or have an effect on gravity – because they don’t carry mass.

But earlier research by the team’s leader, Alberto Nicolis, which was published in Physical Review Letters B in May, provided some experimental evidence that this might not be the case – at least not under extreme conditions.

The experiment was conducted in zero-temperature superfluids, which are a strange type of fluid that flow with no resistance at all at temperatures close to absolute zero.

Under those conditions, Nicolis and his team reported seeing phonons’ trajectories bend upwards, seemingly in opposition to the effect of gravity.

“In a gravitational field phonons slowly accelerate in the opposite direction that you would expect, say, a brick to fall,” one of the team, Rafael Krichevsky, told Live Science.

The effect is too small to measure with existing technology, and there are also other potential explanations for this trajectory that have nothing to do with gravity.

But Nicolis’ latest paper builds on the idea that the phonons were generating some type of negative gravitational field.

They propose that “the (tiny) effective gravitational mass of the phonon generates a (tiny) gravitational field. And the source of this gravitational field travels with the phonon,” the team writes on arXiv.

“Thus, in a very physical sense, the phonon carries (negative) mass.”

Now, we’re not going to go into all the calculations carried out because they’re pretty intense (you can read all about them in the paper).

But in short, the team was able to show mathematically that classical sound waves could carry mass – and not just in superfluids or the quantum world, but in real-world settings.

“We showed that, contrary to common belief, sound waves carry gravitational mass, in a standard Newtonian sense: they are affected by gravity, but they also source gravity,” the team concludes.

They also outline ways we could experimentally test this idea going forward.

And that’s important, not only because it could shift our fundamental understanding of the sound waves that exist in the world all around us all the time.

But also because this effect could impact the behaviour of other objects in the Universe – like neutron stars, which have incredibly dense cores where sound waves move at nearly the speed of light.

A lot more research is needed, but it’s definitely an intriguing hypothesis to build on.

The paper has been published and can be read in full on arXiv.

See the full article here .

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Columbia University was founded in 1754 as King’s College by royal charter of King George II of England. It is the oldest institution of higher learning in the state of New York and the fifth oldest in the United States.

From Science Alert: “There’s a Tiny Strange Galaxy Orbiting The Milky Way And No One Knows How It Got There”

From Science Alert

10 AUG 2018
MICHELLE STARR

A weird and ancient neighbour.

A galaxy in nearby space called Segue 1 is quite the oddity. It’s very small, and very faint, it hangs out very close to the Milky Way, and no one knows quite where it came from.

The region of sky where Segue 1 was found (left) and the galaxy itself (right). (Sloan Digital Sky Survey and M. Geha)

But now astronomers have accurately measured its movement for the first time, which has finally offered some clues.

So what, exactly, is Segue 1? Well, in the last decade or so, our telescope technology had grown powerful enough to spot a small new class of galaxy. They are very compact, occupying the space somewhere between a globular cluster and a dwarf galaxy.

They’re called ultra-faint dwarf spheroidal galaxies, and Segue 1 was the first to be discovered in 2006 data from the Sloan Digital Sky Survey. The paper describing it was published in 2007 [The Astrophysical Journal].

SDSS Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude 2,788 meters (9,147 ft)

It’s filled with ageing or very old stars, dating back to the early Universe.

It has low metal content, which is consistent with a very old object – metals didn’t propagate in the Universe until a generation or two of stars had gone supernova, forging heavy elements in their death.

Segue 1 also has a luminosity, or brightness, of around just 300 Suns. That’s much fainter than a typical globular cluster, which was what it was originally taken for.

In fact, astronomers aren’t entirely sure that it isn’t a globular cluster yet – the difference seems to lie in the two objects’ formation history – although this new research may have answered that question about Segue 1.

In addition to figuring out whether Segue 1 is a galaxy or a globular cluster (oops, headline spoilers), the research team wanted to know where it came from, and exactly how it ended up orbiting the Milky Way at a distance of just 23,000 parsecs (75,000 light-years).

They used data from the Sloan Digital Sky Survey and the Large Binocular Camera over a baseline of 10 years to calculate Segue 1’s proper motion. And they found that it orbits the Milky Way once every 600 million years.

U Arizona Large Binocular Telescope, Mount Graham, Arizona, USA, Altitude 3,221 m (10,568 ft). The Large Binocular Telescope Interferometer, or LBTI, is a ground-based instrument connecting two 8-meter class telescopes on Mount Graham in Arizona to form the largest single-mount telescope in the world. The interferometer is designed to detect and study stars and planets outside our solar system. Image credit: NASA/JPL-Caltech.

Large Binocular Cameras on the Large Binocular Telescope

That’s really tight. But it’s also too far away for Segue 1 to have been a tidally disrupted star cluster – one on the verge of being annihilated by the gravity of the Milky Way.

This means it’s more likely to fall into the “galaxy” category – which supports previous findings that, even though the galaxy has low metallicity, it has a significant spread of iron, something not found in globular clusters.

So that’s two points to Gryffindor the galaxy interpretation.

As for how it got there? Well, that’s still not a certainty. The researchers found two scenarios the most plausible.

Of those two, the less likely is that Segue 1 was a satellite around a different galaxy. This galaxy collided with the Milky Way around 12 billion years ago, and left Segue 1 swirling around on its own.

We know this is possible – the Milky Way has certainly fused with a number of other galaxies in the past, which astronomers can ascertain by the ripples those collisions left behind.

Segue 1’s orbit isn’t consistent with any of those known collisions, but it’s entirely possible there was one astronomers haven’t discovered yet.

The second option – and the one the research team believes a more likely scenario, at 75 percent probability – is that Segue 1 was just wandering around space, minding its own business, when, one day about 8 billion years ago, it got captured into a Milky Way orbit.

Future observations and analyses may help characterise Segue 1 more clearly, but for now, it’s looking like the little guy is a one awesomely weird galactic neighbour.

The full paper has been published in The Astrophysical Journal.

See the full article here .

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From Science Alert: “This Dizzying Galaxy Supercluster Will Change Your Perspective on The Cosmos”

From Science Alert

22 JUL 2018
PETER DOCKRILL

Saraswati supercluster (IUCAA)

The mass of 20 million billion Suns.

Last year, astronomers discovered a massive supercluster of galaxies located approximately 4 billion light-years from Earth – and not only is it one of the largest known structures in the cosmos, it’s also the most distant supercluster we’ve ever observed.

See, in space, everything is a question of perspective. From where you sit, the planet you’re reading this on may seem like a pretty big deal, but it’s only a tiny overall part of our Solar System, which in turn is basically an almost insignificant speck making up our galaxy, the Milky Way.

Our Solar System from Amazon

Milky Way NASA/JPL-Caltech /ESO R. Hurt

But we can still go bigger. Galaxies themselves are subsumed into larger stacks called galaxy groups and clusters – and then there are superclusters: unimaginably vast cosmic aggregations that collect galaxy clusters like a handful of spare change.

Laniakea supercluster. From Nature The Laniakea supercluster of galaxies R. Brent Tully, Hélène Courtois, Yehuda Hoffman & Daniel Pomarède at http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html. Milky Way is the red dot.

It’s one of these handfuls that a team of astronomers in India has now identified, locating a previously unknown dense supercluster that they’ve named after the ancient Sarasvati River.

The Saraswati supercluster, discovered by researchers from the Inter University Centre for Astronomy & Astrophysics (IUCAA), spans an epic swathe of space measuring some 600 million light-years across – in which, the team estimates, lies the equivalent combined mass of over 20 million billion Suns.

Aside from its stupendous size and mass, what makes the find so significant is that so far astronomers haven’t actually identified that many superclusters, meaning Saraswati is joining the ranks of some pretty elite company.

“Previously only a few comparatively large superclusters have been reported,” explain two of the team, astronomers Joydeep Bagchi and Shishir Sankhyayan, “for example, the ‘Shapley Concentration’ or the ‘Sloan Great Wall’ in the nearby Universe.”

Shapely Supercluster from Richard Powell

Sloan Great Wall, SDSS

But what also sets Saraswati apart is its far-flung perch, sitting approximately 4 billion light-years away from you and me.

“It is the first time that we have seen a supercluster that is so far away,” one of the team, Somak Raychaudhury, who also originally helped to identify the Shapley Concentration, told Shubashree Desikan at The Hindu.

“Even the Shapley is about 8 to 10 times closer.”

The two most massive galaxy clusters within in Saraswati supercluster. (IUCAA)

The researchers located Saraswati by examining data from the Sloan Digital Sky Survey, and say that the supercluster contains at least 43 galaxy groups and clusters, comprising about 400 galaxies all up.

What’s most exciting is that Saraswati’s extreme distance from Earth means that the light we’re seeing from has travelled an awfully long way to get here – and so shows us what the supercluster looked like when the Universe was only 10 billion years old.

Peering back in time like that could help us to understand how these massive superstructures come to be, and let us examine the conditions for their development in the early Universe.

“Since a structure of this vastness will only grow extremely slowly, taking many billions of years, it carries with it a sort of record of the entire history of its formation,” Bagchi explained to New Scientist.

That said, Saraswati’s looming presence 4 billion years ago did come as something of a surprise to the researchers, given our current understanding of galactic evolution suggests that superclusters would not have had enough time to form when the Universe was only 10 billions old..

What that could mean is that newer theoretical concepts – such as dark energy and dark matter, both of which scientists are still struggling to fully fathom – may have played a decisive role here.

Dark Energy Survey

Dark Energy Camera [DECam], built at FNAL

NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

Dark Matter Research

Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

Scientists studying the cosmic microwave background hope to learn about more than just how the universe grew—it could also offer insight into dark matter, dark energy and the mass of the neutrino.

Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

Dark Matter Particle Explorer China

DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB deep in Sudbury’s Creighton Mine

LUX Dark matter Experiment at SURF, Lead, SD, USA

ADMX Axion Dark Matter Experiment, U Uashington

“Theory has always been confounded by nature,” Raychaudhury told The Hindu.

“It is true that the balance between dark matter and dark energy can produce large structures, but a supercluster of this size does present an enigma.”

So while the Saraswati supercluster may have finally been revealed, it seems like an even larger, deeper truth still lies in check – just waiting to be discovered.

The findings were published in The Astrophysical Journal.

See the full article here .

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From Cornell University via Science Alert: “A Genius Microscopy Method Just Set a Record in Imaging Individual Atoms”

From Cornell University

via

Science Alert

20 JUL 2018
MIKE MCRAE

Two overlaid sheets of molybdenum disulfide (Cornell University)

Electron microscopes have been capable of taking snapshots of individual atoms for nearly half a century. But we’ve never seen anything quite on this scale.

A new method for catching and measuring the spray of electron beams is giving us a whole new resolution of the sub-ångström world, opening the way to studying molecular structures that would be impossible to see using existing methods.

Last year, engineers at Cornell University in the US performed the equivalent of eye surgery on the traditional electron microscope, ditching the need for corrective lenses and improving the way the eye itself collects and measures light.

Now we have evidence of exactly what that technology can achieve, measuring the bonds between atoms with unprecedented clarity.

At a fundamental level, all microscopes work in a fairly similar way – an object is showered in waves of energy, which are collected and arranged in such a way that we can deduce its shape. Smaller waves mean smaller details.

Electrons can have pretty small wave-like properties that depend on the energy they contain, making them perfect for seeing extra small objects. Instead of lenses, they’re focussed using electromagnetic fields.

Aberrations in these fields can limit the size of objects we can see, much as deviations in lenses can blur images. Engineers usually fix these with the electron microscope equivalent of glasses, adding corrective devices to ‘fix’ the picture.

This fix only goes so far, though. Multiple aberrations demand additional devices, which could theoretically pile up to the point that it’s an engineering nightmare.

A device called an electron microscope pixel array detector (EMPAD) does away with the need for these ‘glasses’ by taking another approach. It’s a catcher’s mitt for electrons that bounce off the sample made up of a 128 x 128 array of electron-sensitive pixels.

Rather than build an image based on the location of the electrons, it detects the angles of each electron’s reflection.

Working backwards using a technique usually applied to X-ray microscopy called ptychography, it’s possible to build a four-dimensional map that tells not only where the electrons came from, but their momentum as well.

The team put the combination of EMPAD and ptychography to the test by analysing the structure of two stacked sheets of molybdenum disulfide, each a single atom thick.

By rotating one sheet a few degrees, they could compare distances in overlapping atoms, setting a record of resolving a distance of just 0.39 ångströms.

“It’s essentially the world’s smallest ruler,” says physicist Sol Gruner.

The lattice (pictured above) was so clear, they spotted a single missing sulphur atom.

But apart from bragging rights, the technique has another massive advantage.

Electron waves can be made smaller by pumping up their energy. More energy means shorter wavelengths. State-of-the-art microscopes can emit streams of electrons at 300 kiloelectronvolts that can resolve details just under 0.05 nanometres, or 0.5 ångströms.

But more energy can also turn those electrons from a gentle sprinkle of particles into a machine gun burst, putting molecules at risk of disintegrating.

Since this beam was a gentle 80 keV, the electrons weren’t energetic enough to break up the structure of the molybdenum disulfide sheets, as they might in a more traditional setup.

Lower energy electron beams mean we can now study bonds in delicate molecules like never before, giving electron microscopy a more gentle touch while providing a whole new level of detail.

This is some artwork we look forward to hanging on our wall.

This research was published in Nature.

See the full article here .

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Once called “the first American university” by educational historian Frederick Rudolph, Cornell University represents a distinctive mix of eminent scholarship and democratic ideals. Adding practical subjects to the classics and admitting qualified students regardless of nationality, race, social circumstance, gender, or religion was quite a departure when Cornell was founded in 1865.

Today’s Cornell reflects this heritage of egalitarian excellence. It is home to the nation’s first colleges devoted to hotel administration, industrial and labor relations, and veterinary medicine. Both a private university and the land-grant institution of New York State, Cornell University is the most educationally diverse member of the Ivy League.

On the Ithaca campus alone nearly 20,000 students representing every state and 120 countries choose from among 4,000 courses in 11 undergraduate, graduate, and professional schools. Many undergraduates participate in a wide range of interdisciplinary programs, play meaningful roles in original research, and study in Cornell programs in Washington, New York City, and the world over.

From Southwest Research Institute via Science Alert: “Never-Before-Seen Structures Have Been Detected in Our Sun’s Corona”

From Southwest Research Institute

via

Science Alert

19 JUL 2018
MICHELLE STARR

DeForest et al./The Astrophysical Journal

Using longer exposures and sophisticated processing techniques, scientists have taken extraordinarily high-fidelity pictures of the Sun’s outer atmosphere – what we call the corona – and discovered fine details that have never been detected before.

The Sun is a complex object, and with the soon-to-be-launched Parker Solar Probe we’re on the verge of learning so much more about it.

NASA Parker Solar Probe Plus

But there’s still a lot we can do with our current technology, as scientists from the Southwest Research Institute (SwRI) have just demonstrated.

The team used the COR-2 coronagraph instrument on NASA’s Solar and Terrestrial Relations Observatory-A (STEREO-A) to study details in the Sun’s outer atmosphere.

NASA/STEREO spacecraft

This instrument takes images of the atmosphere by using what is known as an occulting disc – a disc placed in front of the lens that blocks out the actual Sun from the image, and therefore the light that would overwhelm the fine details in the plasma of the Sun’s atmosphere.

The corona is extremely hot, much hotter than the inner photosphere’s 5,800 Kelvin, coming in at between 1 and 3 million Kelvin. It’s also the source of solar wind – the constant stream of charged particles that flows out from the Sun in all directions.

When measurements of the solar wind are taken near Earth, the magnetic fields embedded therein are complex and interwoven, but it’s unclear when this turbulence occurs.

“In deep space, the solar wind is turbulent and gusty,” says solar physicist Craig DeForest of the SwRI.

“But how did it get that way? Did it leave the Sun smooth, and become turbulent as it crossed the solar system, or are the gusts telling us about the Sun itself?”

If the turbulence was occurring at the source of the solar wind – the Sun – then we should have been able to see complex structures in the corona as the cause of it, but previous observations showed no such structures.

Instead, they showed the corona as a smooth, laminar structure. Except, as it turns out, that wasn’t the case. The structures were there, but we hadn’t been able to obtain a high enough image resolution to see them.

NASA/SwRI/STEREO

“Using new techniques to improve image fidelity, we realised that the corona is not smooth, but structured and dynamic,” DeForest explains. “Every structure that we thought we understood turns out to be made of smaller ones, and to be more dynamic than we thought.”

To obtain the images, the research team ran a special three-day campaign wherein the instrument took more frequent and longer-exposure images than it usually does, allowing more time for light from faint sources to be detected by the coronagraph. But that was only part of the process.

Although the occulting disc does a great job at filtering out the bright light from the Sun, there’s still a great deal of noise in the resulting images, both from the surrounding space and the instrument.

Obviously, since STEREO-A is in space, altering the hardware isn’t an option, so DeForest and his team worked out a technique for identifying and removing that noise, vastly improving the data’s signal-to-noise ratio.

They developed new filtering algorithms to separate the corona from noise, and adjust brightness. And, perhaps more challengingly, correct for the blur caused by the motion of the solar wind.

They discovered that the coronal loops known as streamers – which can erupt into the coronal mass ejections that send plasma and particles shooting out into space – are not one single structure.

“There is no such thing as a single streamer,” DeForest said. “The streamers themselves are composed of myriad fine strands that, together, average to produce a brighter feature.”

They also found there’s no such thing as the Alfvén surface – a theoretical, sheet-like boundary where the solar wind starts moving forward faster than waves can travel backwards through it, and it disconnects from the Sun, moving beyond its influence.

Instead, DeForest said, “There’s a wide ‘no-man’s land’ or ‘Alfvén zone’ where the solar wind gradually disconnects from the Sun, rather than a single clear boundary.”

But the research also presented a new mystery to probe, as well. At a distance of about 10 solar radii the solar wind suddenly changes character. But it returns to normal farther out from the Sun, indicating that there’s some interesting physics happening at 10 solar radii.

Figuring out what that is may require some help from Parker, for which this research is key. Parker is due to launch in August.

Meanwhile, the team’s research has been published in The Astrophysical Journal.

See the full article here .

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Southwest Research Institute (SwRI) is an independent, nonprofit applied research and development organization. The staff of nearly 2,800 specializes in the creation and transfer of technology in engineering and the physical sciences. SwRI’s technical divisions offer a wide range of technical expertise and services in such areas as engine design and development, emissions certification testing, fuels and lubricants evaluation, chemistry, space science, nondestructive evaluation, automation, mechanical engineering, electronics, and more.

From National Radio Astronomy Observatory via Science Alert: “BREAKING: We Just Found The Brightest Object in The Early Universe – 13 Billion Light-Years Away”

From National Radio Astronomy Observatory

via

Science Alert

9 JUL 2018
MICHELLE STARR

(NASA Goddard)

Astronomers have found the brightest object ever discovered in the early Universe, 13 billion light-years away – a quasar from a time when our Universe was just seven percent of its current age.

A quasar is a galaxy that orbits a supermassive black hole actively feeding on material. The light and radio emissions we see are caused by material around the black hole, called an accretion disk.

This disk contains dust and gas swirling at tremendous speeds like water going down a drain, generating immense friction as it’s pulled by the massive gravitational force of the black hole in the centre.

As they consume matter, these quasar black holes expel powerful jets of plasma at near light-speed from the coronae – regions of hot, swirling gas above and below the accretion disk.

These jets are extremely bright in the radio frequency spectrum. It was this signal emanating from the newly discovered quasar, named PSO J352.4034-15.3373 (P352-15 for short), that was picked up by the Very Long Baseline Array radio telescope.

NRAO/VLBA

“There is a dearth of known strong radio emitters from the Universe’s youth and this is the brightest radio quasar at that epoch by a factor of 10,” said astrophysicist Eduardo Bañados of the Carnegie Institution for Science in Pasadena, California.

(Momjian, et al.; B. Saxton (NRAO/AUI/NSF))

The VLBA’s observations showed the quasar split into three distinct components, for which there are two possible interpretations.

The first is that the black hole is at one end, and the two other components are parts of a single jet. The second is that the black hole is in the middle, with a jet on either side.

According to optical telescopes, which show the quasar in visible light, the position of the black hole aligns with one of the end components – making the first interpretation the most likely.

This means that, by studying and analysing the two parts of the jet, astrophysicists may be able to measure how fast it is expanding.

“This quasar may be the most distant object in which we could measure the speed of such a jet,” said NRAO astronomer Emmanuel Momjian.

On the other hand, if the black hole turns out to be in the centre, it means the jets are much smaller – which would mean a much younger object, or one that is embedded in dense material that’s slowing down the jets.

Further research will need to be done to determine which of the two scenarios is true. In the meantime, P352-15 is still a highly valuable object for study.

It’s not as old as J1342+0928, a quasar also discovered by a team led by Bañados, from when the Universe was only five percent of its current age.

J1342+0928

But the light of quasars can be used to study the intergalactic medium. This is because the hydrogen it travels through on its long journey to Earth changes the light’s spectrum – recently, a quasar was used in just this way to find the Universe’s missing baryonic matter in the space between galaxies.

P352-15 has great potential as a tool of this nature.

“We are seeing P352-15 as it was when the Universe was less than a billion years old,” said astrophysicist Chris Carilli of NRAO.

“This is near the end of a period when the first stars and galaxies were re-ionising the neutral hydrogen atoms that pervaded intergalactic space. Further observations may allow us to use this quasar as a background ‘lamp’ to measure the amount of neutral hydrogen remaining at that time.

“This quasar’s brightness and its great distance make it a unique tool to study the conditions and processes that prevailed in the first galaxies in the Universe.”

The research has been published in The Astrophysical Journal Resolving the Powerful Radio-loud Quasar at z ~ 6, and A Powerful Radio-loud Quasar at the End of Cosmic Reionization.

See the full article here .

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NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

NRAO VLBA

NRAO VLBA

*The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

And the future Expanded Very Large Array (EVLA).

From The Washington Post via Science Alert: “A Huge Number of Asteroids Could Be Traced Back to Five Destroyed Worlds”

From The Washington Post

via

Science Alert

7 JUL 2018
SARAH KAPLAN

An artist’s illustration of two asteroids colliding, producing the “families” we see today. (Don Davis/University of Florida)

A common catastrophic ancestor.

In the beginning, the solar system was little more than a cloud of dust and gas. Then cold temperatures caused the center of the cloud to collapse, forming the Sun.

The newborn star lit up with nuclear fusion, sending light and heat out into the spinning circumstellar disk. Soon that material coalesced into gas planets, ice giants and rocky worlds, creating the solar system we know today.

For years, asteroids were thought of as the leftovers of planet formation — chunks of material that never quite made it to planet size and that were drawn into the crowded belt of rocky remnants that circles the Sun between Mars and Jupiter.

But according to a study published Monday in the journal Nature Astronomy, these were once pieces of worlds, too.

A vast majority of the half-million bodies in the inner asteroid belt may in fact be shrapnel from as few as five parent bodies called “planetesimals,” scientists say.

But the tangled orbits of those lost worlds meant they were doomed to collide, producing fragments that also collided, producing still more fragments in a cataclysmic cascade that’s been going on for more than 4 billion years.

The finding doesn’t only illuminate a “mystery” of the asteroid belt, said Katherine Kretke, a planetary scientist at the Southwest Research Institute who was not involved in the study.

It could also help resolve a debate about the formation of the eight planets — including Earth.

“I find it really exciting that we can look back in time and potentially see evidence of what were the building blocks that built up our solar system,” she said.

“If we can turn back the clock and see the asteroid belt was made by these big planetesimals, that really is telling us something quite definitive about the circumstances that formed our own planet.”

The study’s lead author, University of Florida astronomer Stanley Dermott, didn’t necessarily set out to probe a mystery of solar system formation.

He and his colleagues were looking at data on the dynamics of bodies in the inner asteroid belt in hopes of figuring out what makes an object leave the belt — and potentially fly toward Earth. (For those who are concerned about asteroid collisions, rest assured that Dermott is still studying that question.)

But as Dermott began to look through a database of near-Earth objects, he noticed something strange about many large asteroids: Their orbits were inclined, or tilted, relative to the plane of the rest of the solar system.

“We couldn’t think of any forces that are acting to produce that distribution,” Dermott said.

On the other hand, “if a big asteroid is smashed up and it has a high inclination, then those fragments have that same inclination.”

Scientists have previously known that roughly half of inner-belt asteroids belong to five “families.” But Dermott and his colleagues say their analysis suggests that number is as high as 85 percent.

This finding matches other observations of the asteroid belt, said David Nesvorny, a planetary scientist at SWRI who was not involved with Dermott’s study. Asteroids thought to belong to the same family tend to orbit in clusters and have similar chemical compositions.

There’s an important, if apparent, implication of the idea that asteroids are actually fragments of larger bodies: “It means asteroids are born big,” Nesvorny said.

That finding may help resolve a question about planet formation that has baffled scientists for years.

According to the traditional story of the origin of the solar system, the planets formed slowly from accretion, as particles in the circumstellar disk clumped together to great pebbles, then slightly larger spheres, on and on until they reached their current size.

But when scientists try to re-create this story with computer models, it breaks down.

Rather than growing, these incipient planets tend to splinter after reaching pebble size. How could this process result in bodies the size of those in the asteroid belt, let alone whole planets?

Enter the “born big” hypothesis.

Nesvorny and many others now think that gravity kicks in once clumps in the circumstellar disk reach the pebble stage, swiftly pulling together massive amounts of material to form a huge new planet.

In the inner solar system, this produced small, rocky planets such as Earth; further from the sun, we got gas giants.

But in the space between Mars and Jupiter, the tremendous gravity of the solar system’s largest planet may have made it difficult to grow a large object, Nesvorny said.

The smaller bodies that did emerge, which were probably a tenth of the size of a planet such as Earth, could not have survived the ensuing chaos and collisions; they broke apart and formed the asteroid belt we know today.

Some questions remain about this theory. Tim McCoy, a geologist at the Smithsonian’s National Museum of Natural History, pointed out that most meteorites that fall to Earth don’t look like they come from large parent bodies.

And Kretke suggested that the theory might work better if there were a few dozen parent bodies, rather than just five.

Meanwhile, Nesvorny noted that the inner belt is home to only a tenth of all asteroids — he’d hope to see the analysis applied to the rest of the asteroid belt.

Dermott said he and his colleagues plan to address that question next.

And some day, he added, the research may be applied to other solar systems. Astronomers have found evidence for asteroid belts around Vega and Fomalhaut, stars just a couple dozen light-years away.

“That’s the next big step, and it’s happening in our lifetimes,” Dermott said.

“The whole business of formation and evolution of planets and the question of ‘What do we need to form an Earthlike planet elsewhere?’ is something we can finally discuss in meaningful terms.”

See the full article here .

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Please help promote STEM in your local schools.

Stem Education Coalition

From Science Alert: “These Scientists Have a Tantalising New Answer to The Mysterious ‘Gaia Puzzle’ “

From Science Alert

5 JUL 2018
JAMES DYKE,
TIM LENTON

(Louis Maniquet/Unsplash)

marianaboterop

We will likely never know how life on Earth started. Perhaps in a shallow sunlit pool.

Or in the crushing ocean depths miles beneath the surface near fissures in the Earth’s crust that spewed out hot mineral-rich soup. While there is good evidence for life at least 3.7 billion years ago, we don’t know precisely when it started.

But these passing aeons have produced something perhaps even more remarkable: life has persisted.

Despite massive asteroid impacts, cataclysmic volcano activity and extreme climate change, life has managed to not just cling on to our rocky world but to thrive.

How did this happen? Research we recently published with colleagues in Trends in Ecology and Evolution offers an important part of the answer, providing a new explanation for the Gaia hypothesis.

Developed by scientist and inventor James Lovelock, and microbiologist Lynn Margulis, the Gaia hypothesis originally proposed that life, through its interactions with the Earth’s crust, oceans, and atmosphere, produced a stabilising effect on conditions on the surface of the planet – in particular the composition of the atmosphere and the climate.

With such a self-regulating process in place, life has been able to survive under conditions which would have wiped it out on non-regulating planets.

Lovelock formulated the Gaia hypothesis while working for NASA in the 1960s. He recognised that life has not been a passive passenger on Earth.

Rather it has profoundly remodelled the planet, creating new rocks such as limestone, affecting the atmosphere by producing oxygen, and driving the cycles of elements such as nitrogen, phosphorus and carbon.

Human-produced climate change, which is largely a consequence of us burning fossil fuels and so releasing carbon dioxide, is just the latest way life affects the Earth system.

While it is now accepted that life is a powerful force on the planet, the Gaia hypothesis remains controversial. Despite evidence that surface temperatures have, bar a few notable exceptions, remained within the range required for widespread liquid water, many scientists attribute this simply to good luck.

If the Earth had descended completely into an ice house or hot house (think Mars or Venus) then life would have become extinct and we would not be here to wonder about how it had persisted for so long.

This is a form of anthropic selection argument that says there is nothing to explain.

Clearly, life on Earth has been lucky. In the first instance, the Earth is within the habitable zone – it orbits the sun at a distance that produces surface temperatures required for liquid water.

There are alternative and perhaps more exotic forms of life in the universe, but life as we know it requires water. Life has also been lucky to avoid very large asteroid impacts.

A lump of rock significantly larger than the one that lead to the demise of the dinosaurs some 66 million years ago could have completely sterilised the Earth.

But what if life had been able to push down on one side of the scales of fortune? What if life in some sense made its own luck by reducing the impacts of planetary-scale disturbances?

This leads to the central outstanding issue in the Gaia hypothesis: how is planetary self-regulation meant to work?

While natural selection is a powerful explanatory mechanism that can account for much of the change we observe in species over time, we have been lacking a theory that could explain how the living and non-living elements of a planet produce self-regulation.

Consequently the Gaia hypothesis has typically been considered as interesting but speculative – and not grounded in any testable theory.

Selecting for stability

We think we finally have an explanation for the Gaia hypothesis. The mechanism is “sequential selection”. In principle it’s very simple.

As life emerges on a planet it begins to affect environmental conditions, and this can organise into stabilising states which act like a thermostat and tend to persist, or destabilising runaway states such as the snowball Earth events that nearly extinguished the beginnings of complex life more than 600 million years ago.

If it stabilises then the scene is set for further biological evolution that will in time reconfigure the set of interactions between life and planet. A famous example is the origin of oxygen-producing photosynthesis around 3 billion years ago, in a world previously devoid of oxygen.

If these newer interactions are stabilising, then the planetary-system continues to self-regulate. But new interactions can also produce disruptions and runaway feedbacks.

In the case of photosynthesis it led to an abrupt rise in atmospheric oxygen levels in the “Great Oxidation Event” around 2.3 billion years ago.

This was one of the rare periods in Earth’s history where the change was so pronounced it probably wiped out much of the incumbent biosphere, effectively rebooting the system.

The chances of life and environment spontaneously organising into self-regulating states may be much higher than you would expect.

In fact, given sufficient biodiversity, it may be extremely likely. But there is a limit to this stability.

Push the system too far and it may go beyond a tipping point and rapidly collapse to a new and potentially very different state.

This isn’t a purely theoretical exercise, as we think we may able to test the theory in a number of different ways. At the smallest scale that would involve experiments with diverse bacterial colonies.

On a much larger scale it would involve searching for other biospheres around other stars which we could use to estimate the total number of biospheres in the universe – and so not only how likely it is for life to emerge, but also to persist.

The relevance of our findings to current concerns over climate change has not escaped us. Whatever humans do life will carry on in one way or another.

But if we continue to emit greenhouse gasses and so change the atmosphere, then we risk producing dangerous and potentially runaway climate change.

This could eventually stop human civilisation affecting the atmosphere, if only because there will not be any human civilisation left.

The ConversationGaian self-regulation may be very effective. But there is no evidence that it prefers one form of life over another. Countless species have emerged and then disappeared from the Earth over the past 3.7 billion years.

We have no reason to think that Homo sapiens are any different in that respect.

See the full article here .

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Please help promote STEM in your local schools.

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From University of Toronto via Science Alert: “A Strange Type of Matter Might Lie Inside Neutron Stars, And It Breaks The Periodic Table”

From University of Toronto

via

Science Alert

(gremlin/istock)

20 JUN 2018
MIKE MCRAE

This is amazing and we are freaking out.

A group of physicists are questioning our understanding of how quarks – a type of elementary particle – arrange themselves under extreme conditions. And their quest is revealing that elements beyond the edge of the periodic table might be far more weird than we thought.

Periodic table Sept 2017. Wikipedia

Deep in the depths of the periodic table there are monsters made of a unique arrangement of subatomic particles. As far as elements go, they come no bigger than oganesson – a behemoth that contains 118 protons and has an atomic mass of just under 300.

That’s not to say protons and neutrons can’t be arranged into even bigger clumps and still remain somewhat stable for longer than an eye blink. But for all practical purposes, nobody has discovered it yet.

While scientists speculate over how far the frontiers of the periodic table stretch, it’s becoming clear that as atoms get bigger, the usual rules governing their behaviour change.

In this latest study, physicists from the University of Toronto argue that the constituent particles making up an atom’s protons and neutrons could break their usual bonds under extreme conditions and still retain enough stability for the atom to stick around.

There are six types of these particles, called quarks, with the rather odd names of up, down, charm, strange, top, and bottom. Protons contain two up types and a down type. Neutrons, on the other hand, are made of two downs and a single up.

Quarks aren’t limited to these configurations, though finding other arrangements is often rare thanks to the fact few stay stable very long.

A little over thirty years ago, a physicist named Edward Witten proposed that the energy keeping combinations of quarks in triplets could achieve something of a balance if put under sufficient pressure, such as that inside a neutron star.

This ‘strange quark matter’ (or SQM) would be a relatively equal mix of up, down, and strange quarks arranged not in threes, but as a liquid of numerous buzzing particles.

Given the fact up and down quarks get along well enough to form teams inside protons and neutrons, the possibility of making quark matter without strange quarks to mix things up has been generally dismissed.

According to physicists Bob Holdom, Jing Ren, and Chen Zhang, doing the actual sums reveals up-down quark matter, or udQM, might not only be possible, but preferable.

“Physicists have been searching for SQM for decades,” the researchers told Lisa Zyga at phys.org. “From our results, many searches may have been looking in the wrong place.”

The team went back to basics and question the lowest energy state of a big bunch of squirming quarks.

They discovered that the ground state – that comfortable lobby of energy levels for particles – for udQM could actually be lower than both SQM and the ground state of the triplets inside protons and neutrons.

So if bunches of quarks are given enough of a push, they could force the ups and downs to pool into a liquid mess at energies that don’t need the help of strange quarks.

Neutron stars could provide just such a squeeze, but it’s no secret that the hearts of atoms themselves are pretty intense places as far as forces go.

The team suggest elements with atomic masses greater than 300 might also provide the right conditions to force up and down quarks to loosen up and party.

Making these elements would be a challenge that would require some way to pile on the neutrons to make supermassive elements stable enough.

But the lower ground states of udQM point the way to stable regions beyond the edges of the periodic table.

Exactly what these heavy elements look like or how they behave is hard to say for now, but it’s unlikely they’d be following the usual rules.

There’s also a chance that udQM could shoot across the Universe in the form of cosmic rays, and potentially be caught here on Earth. Or even produced inside particle accelerators.

“Knowing better where to look for udQM might then help to achieve an old idea: that of using quark matter as a new source of energy,” the researchers claim.

Stable droplets of quarks wouldn’t behave like usual quark clusters found in protons and neutrons, with lower masses that could potentially make them easier to control.

Quark matter reactors sound like the stuff of science fiction. But if this research is anything to go by, a whole new field of applied physics could be just over the horizon.

This research was published in Physical Review Letters.

See the full article here .

five-ways-keep-your-child-safe-school-shootings
Please help promote STEM in your local schools.

Stem Education Coalition

Established in 1827, the University of Toronto has one of the strongest research and teaching faculties in North America, presenting top students at all levels with an intellectual environment unmatched in depth and breadth on any other Canadian campus.

Established in 1827, the University of Toronto has one of the strongest research and teaching faculties in North America, presenting top students at all levels with an intellectual environment unmatched in depth and breadth on any other Canadian campus.