Out of Nothing: An Emergent Universe

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If you spin an umbrella under a pouring rain, you'd have all the fun of seeing droplets of rain spinning away so fast from the edges of the umbrella.

Now let's go a little further and think about the speed by which those droplets are spinning away in the shape of a ring: under the basic laws of motion and gravity, we would have a figure that adequately accounts for them.

Now let's take this a heck further and assume the umbrella is the Milky Way galaxy, and let's add another one to stand for the Andromeda galaxy, our twin galaxy nearby. For the droplets, let smaller galaxies take their places. Hold the picture in your head and let's say we have the mathematics that should describe them. All good so far, except this: in the real world (or universe if you are up to it), the mathematics fail in accounting for the way those ring of galaxies are flying away from the Milky Way and the Andromeda galaxy. So what gives?

The following is a good description of this current headache from Einstein's General Theory of Relativity describing the physics of gravity in the universe. And bear in mind that not only this event of rebellious spinning galaxies, but also the behavior of galaxy spin in general are keeping cosmologists busy these days, either excited to find they're on the verge of new science, or frustrated at the possible dead corners within their lifetime.

Let's go back to our spinning droplets and umbrella—our Milky Way, Andromeda, and those little galaxies really.

So scientists have discovered that a gigantic ring of galaxies stretching 10 million light-years wide is speeding away from our own galaxy so fast, our current physics models can't explain it.

Describing the structure as expanding rapidly like a "mini Big Bang," the team thinks it was formed by a near-miss between the Milky Way and our neighboring galaxy, Andromeda, which created a 'sling-shot' of several smaller galaxies. The only problem is the result is at odds with the conditions predicted by Einstein's theory of relativity.

"If Einstein's gravity were correct, our galaxy would never come close enough to Andromeda to scatter anything that fast," says one of the team, Hongsheng Zhao from the University of St Andrews in Scotland.

Zhao and his team have been investigating the movements of a ring of small galaxies in the Local Group region of the Universe—a group of at least 54 galaxies, which has its two largest galaxies, the Milky Way and the Andromeda Galaxy, roughly at its center.

The Milky Way is currently about 2.5 million light-years away from Andromeda, but our neighboring galaxy is careening towards us at speeds of roughly 402,336 km/h (250,000 mph).

Based on Einstein's theory of relativity, astronomers estimate that 3.75 billion years from now, the Milky Way and Andromeda will collide, and in the billions of years that follow, the two will be ripped apart to form a brand new galaxy.

But have these two galaxies already experienced a near-miss?

Back in 2013, Zhao and his colleagues suggested that 7 to 11 billion years ago, the Milky Way and the Andromeda Galaxy came scarily close to each other, resulting a "tsunami-like wake" in space that would have flung smaller galaxies out into their current positions.

You can see a more recent example of this in the near-miss of two spiral galaxies, NGC 5426 and NGC 5427.

Having investigated this hypothesis further, the team now says the current velocities of these galaxies agree with this scenario - they appear to be speeding away from us so fast, our current physics models can't explain it.

"The high galactocentric radial velocities (GRVs) of some Local Group galaxies must have been caused by forces acting on them that our model does not account for," they conclude in their paper.

Not only that, but these galaxies exist on the exact same plane of the Universe as the Milky Way and the Andromeda Galaxy, which is unlikely to be a coincidence, they argue.

"The ring-like distribution is very peculiar. These small galaxies are like a string of raindrops flung out from a spinning umbrella," says one of the researchers, Indranil Banik.

"I found there is barely a 1 in 640 chance for randomly distributed galaxies to line up in the observed way. I traced their origin to a dynamical event when the Universe was only half its present age."

The problem with this scenario is that not only does Einstein's theory of relativity fail to explain the velocities of these galaxies, it also states that this near-miss should have resulted in the merge of the Milky Way and the Andromeda Galaxy billions of years ago—which obviously never happened.

The reason our current models of gravity require this to have happened is because of one of the most controversial parts of Einstein's theory—dark matter.

Einstein's theory of relativity is about as robust as theories get in terms of predicting the behavior of our Universe, but several major gravitational effects cannot be explained unless we shoehorn this strange and frustratingly elusive form of matter into the mix.

Thought to make up more than 80 percent of the mass of the entire Universe, dark matter has yet to be directly observed, and it's not for a lack of effort—a recent US$10 million experiment to find traces of dark matter particles failed to find anything after an exhaustive 20-month search.

But the way that light bends as it travels through the cosmos, and the peculiar way galaxies rotate, cannot be explained without the influence of dark matter in the Universe.

According to Zhao and his team, we could be looking at two possibilities here—either Einstein's theory of relativity is fine, and there's some other explanation for why this galaxy ring is speeding so fast (and why we haven't been able to detect dark matter), or our current model of gravity needs to be revised.

"Several aspects of the spatial distribution of these galaxies would be expected to occur if there was a past close MW-M31 flyby," the team concludes in a second study released on their latest findings.

"Such an event only makes sense in the context of certain modified gravity theories, where galaxies lack massive dark matter halos and their associated dynamical friction in close encounters, which would otherwise cause a merger."

The hypothesis recalls another recent paper that argued our current understanding of gravity is wrong.

Last year, physicist Erik Verlinde from the University of Amsterdam suggested that gravity isn't a fundamental force of nature at all, but is instead an 'emergent phenomenon' of something we've yet to define—just as temperature is an emergent phenomenon of the movement of particles.

As Fiona MacDonald reported at that time, Verlinde argues that if we only proposed dark matter to make up for an inconsistency with gravity, then maybe the issue isn't dark matter at all—maybe the problem is that we don't really understand how gravity works.

To be clear, both Zhao's team and Verlinde's conclusions are just hypotheses right now, and we have a long way to go before we start tearing apart the foundations of modern physics.

But no one can deny that there are some serious holes in our current understanding of the Universe, not least of which is the fact that gravity and other aspects of general relativity don't gel with quantum mechanics, which has led researchers to seek out a new 'theory of everything' that bridges the gap between the two.

When they were investigating the hypothesised 'near-miss' of Andromeda and the Milky Way back in 2013, Zhao and his team found that a different model of gravitational behaviour—known as Milgrom's Modified Newtonian Dynamics (MOND)—explained the movements of nearby galaxies better than the standard model of physics did.

We'll have to wait and see where all this leads, but it's pretty cool to think that we're likely to see some big things happen in theoretical physics in the decades to come—whether Einstein was right or not.

Zhao and his team's latest findings have been published in two papers, one in Monthly Notices of the Royal Astronomical Society, and another that has so far only been released on the pre-print website, arXiv.org.

This Gigantic Ring of Galaxies Could Bring Einstein's Gravity Into Question

 

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Scientists have discovered that the forces controlling the behavior of a black hole's event horizon are also at play in superfluid helium, an extraordinary liquid that flows without friction.

This entanglement area law has now been observed at both the vast scale of black holes and the atomic scale of cold helium, and could be the key to finally establishing the long sought-after quantum theory of gravity—the solution to one of the deepest problems in theoretical physics today.

The fact that an entanglement area law can apply to both black holes and helium "is weird," says one of the team, physicist Adrian Del Maestro from the University of Vermont, "and it points to a deeper understanding of reality."

Black holes are strange enough on their own, but their relationship to entropy—the disorder of the Universe—is something that renowned physicist (and soon-to-be space tourist) Stephen Hawking found himself particularly absorbed by.

Entropy is how we describe the progression of a system from order to disorder—an untouched egg has low entropy, but a whisked egg has high entropy.

And just as you can't unwhisk an egg, a system can only ever progress from low to high entropy—in our Universe, at least.

Thanks to entropy, the arrow of time only ever moves forward, and since the moment of the Big Bang, the Universe and everything in it has been gradually moving towards heightened chaos.

In the 1970s, Hawking and fellow theoretical physicist Jacob Bekenstein discovered that when matter is unfortunate enough to wander too close to the event horizon of a black hole and fall in, the information that's then added to the black hole—a form of entropy—only increases as fast as the black hole's surface area increases.

That's pretty weird, because the increasing volume of the black hole doesn't seem to be a factor.

"If you double the size of a box, you expect to be able to double the amount of information in that box," physicist Christopher Herdman of the University of Waterloo in Canada, the lead researcher on the project, told Science News.

Think of it like a filing cabinet—it wouldn't make any sense to use only its surface area measurements to figure out how many files you could fit inside, without taking its volume into consideration.

But that's what Hawking and Bekenstein discovered in black holes out in deep space, and it now looks like this counter-intuitive entanglement area law also applies to special types of atoms in our labs.

"We have found the same type of law is obeyed for quantum information in superfluid helium," says Del Maestro in a press statement.

To figure this out, the team came up with an exact simulation of superfluid helium-4—helium that has been chilled to just 2 degrees above absolute zero. Absolute zero (0 Kelvin, -273.15°C, or -459.67°F) is the absolute limit of cold in the Universe.

At this point, the helium transforms from a gas into a fluid with zero viscosity, which allows it to flow without any loss of kinetic energy. That means if you put some superfluid helium in a cup and gave it a spin, that helium would literally spin forever.

This state of matter is so strange it has the ability to flow 'upwards' against gravity, and climb up and over the sides of a dish:

In superfluid helium, the individual atoms that made up the substance can no longer be identified as separate entities—they've become quantum entangled with one another, and now share an existence.

When Del Maestro and his colleagues uploaded their simulation to two supercomputers, they were able to run separate simulations of 64 helium atoms as they transitioned to a superfluid.

Within this superfluid, they established two hypothetical sections—a sphere of superfluid, and the superfluid that surrounded it—and kept track of the amount of entangled quantum information shared between them as the sphere was increased.

If you think back to the black holes, this entangled quantum information is analogous to the information falling over the event horizon to increase the entropy inside.

Just like what Hawking and Bekenstein had found, they watched as the amount of entangled quantum information shared between two regions the superfluid was determined by the surface area of the sphere, but not its volume.

"Like a holograph, it seems that a three-dimensional volume of space is entirely encoded on its two-dimensional surface. Just like a black hole," the team describes.

According to Emily Conover at Science News, while the phenomenon had previously been predicted in superfluids, this is the first time that it has been demonstrated in simulations of a naturally occurring state of matter.

And that's important, because the phenomenon of quantum entanglement does not gel with the standard model of physics, and made Einstein himself deeply uncomfortable, but it's here to stay, and we need better ways of studying it.

"Entanglement is non-classical information shared between parts of a quantum state. [It's] the characteristic trait of quantum mechanics that is most foreign to our classical reality," Del Maestro says in a press statement.

"Our classical theory of gravity relies on knowing exactly the shape or geometry of space-time."

As theories that explain the behavior of all the vast and tiny things in our Universe, Einstein's theory of relativity and quantum mechanics don't mesh, and one of the most significant problems in modern physics is finding a way to combine the two into a universal quantum theory of gravity.

Maybe finally being able to watch the strangeness of quantum entanglement in a naturally occurring state of matter will get us closer to that goal.

The research was published in Nature Physics.


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Ripples in spacetime just got violent: scientists have identified a runaway supermassive black hole that appears to have been dislodged from its galactic centre by the extraordinary force of gravitational waves - ripples in space-time that were first predicted by Einstein more than a century ago.

This black hole is thought to weigh more than 1 billion Suns, and is tearing through its galaxy at speeds of roughly 7.6 million km/h (4.7 million mph). It's so far cleared an intimidating 35,000 light-years, and there's no telling where it's going to end up.

"We estimate that it took the equivalent energy of 100 million supernovae exploding simultaneously to jettison the black hole," says one of the team, Stefano Bianchi from the Roma Tre University in Italy.

While past studies have pointed to a number of cosmic anomalies in deep space as being potential 'rogue' black holes, scientists have yet to confirm any of these shadowy runaways.

But Bianchi and his team say theirs is not only an unusually strong case for a runaway black hole—it's also the first time that astronomers have found a supermassive black hole at such a large distance from its galaxy centre.

Supermassive black holes contain hundreds of millions of times the mass of our Sun. The biggest ones can even be as heavy as 10 billion Suns. There are also massive black holes, which are 100 to 100,000 times more massive than our Sun.

Massive and supermassive black holes are thought to be at the heart of every galaxy in the Universe. This looming presence is intrinsic to the existence of a galaxy—they even grow in tandem with each other—but no one's entirely sure why they always end up at the centre.

Regardless of how they got there, supermassive black holes tend to stay put in the centre of a galaxy—but physicists have hypothesised that on very rare occasions, something catastrophic can knock them free.

In this case, the Hubble Space Telescope detected a bright quasar—the energetic signature of an active black hole—some 35, 000 light-years from the centre. To put that into perspective, 1 light-year is roughly 9.5 trillion km (5.88 trillion miles).

Bianchi and his team have estimated that the black hole is travelling at speed of 7.6 million km/h (4.7 million mph), which means it could get from Earth to the Moon in 3 minutes.

"That's fast enough for the black hole to escape the galaxy in 20 million years and roam through the Universe forever," the team points out.

Will it one day make it to our own cosmic neighbourhood? There's no way of knowing what this violent runaway is capable of, but at least we can take comfort in the fact that we'll be long gone if or when it happens to drop by.

The research has been published in Astronomy & Astrophysics, and you can access it for free here.


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Of all the unexplained things in our Universe, fast radio bursts are arguably the weirdest. They're some of the most elusive and explosive signals ever detected in space, and while they last for mere milliseconds, they generate as much energy as 500 million Suns.

Last year, researchers found 16 Fast Radio Bursts all coming from the same source beyond our Milky Way, and now Harvard physicists have proposed that signals like these could be evidence of advanced alien technology.

"Fast Radio Bursts are exceedingly bright, given their short duration and origin at great distances, and we haven't identified a possible natural source with any confidence," says theoretical physicist Avi Loeb from the Harvard-Smithsonian Centre for Astrophysics.

"An artificial origin is worth contemplating and checking."

Fast Radio Bursts (FRB) aren't all that uncommon—since the first one was detected back in 2007, researchers predict that around 2,000 of these things are lighting up the Universe every single day.

But the problem with detecting and analyzing these signals is that they're not only incredibly fleeting—less than 5 milliseconds in duration—they've been frustratingly random in origin.

That was until late 2016, when researchers detected what appears to be the first repeating FRB—11 high-energy radio bursts all coming from a single source, way out in the distant Universe.

Earlier this year, six more FRBs were detected coming from the same location, and researchers managed to pinpoint their location to a faint dwarf galaxy, more than 3 billion light-years from Earth.

That was a huge development, because until that point, the FRBs we'd detected had all come from random origins in space, making follow-up observations impossible.

And if you wanted to go searching for some more FRBs to better understand them, your hunting ground is literally the size of the entire known Universe.

But despite finding the first ever repeating FRBs, collectively known as FRB 121102, no one has been able to provide a convincing explanation for what's causing such powerful outbursts.

The leading hypotheses right now are that these signals result from the most volatile and explosive events in the Universe—supermassive black holes coughing up cosmic material; explosions of superluminous supernovae; or rotating magnetars—a type of neutron star that pummels everything around it with intense magnetic fields.

But this is all just speculation, based on the assumption that such powerful signals would originate from the most powerful events we've ever detected.

Now Loeb and his team say that in the absence of an explanation everyone can agree on, we should be looking at some slightly less … natural sources.

"[W]e have posited that Fast Radio Bursts are beams set up by extragalactic civilizations to potentially power lightsails," they describe in a new paper. Now who says scientists have no sense of humor?

If you're not familiar with lightsails, the technology is still in its infancy—at least, on Earth—but has the potential to revolutionize space exploration, with NASA researchers estimating that we could get one to Mars in three days flat.

Known as 'photonic propulsion' systems, lightsails are powered by the momentum of photons (particles of light), which could either be harnessed from the Sun's rays, like Bill Nye's light sail, or giant Earth-based lasers, like this NASA proposal.

That means virtually zero fuel would be required, and journeys could last as long as the physical parts could hold.
With that in mind, Loeb and his team investigated the possibility that Fast Radio Bursts were coming from an enormous radio transmitter on a distant alien planet, that beams FRB-like signals across the Universe to propel giant light sails.

Using data collected by known FRBs, they calculated that if the signals were emitted by an enormous, solar-powered radio transmitter billions of light-years away, it would need a planet-sized area to collect enough sunlight to produce signals strong enough for us to detect here on Earth.

And not just any planet—it would need to be twice the size of Earth. So maybe even a Dyson Sphere?

Here's the basic premise, based on a proposal by Breakthrough Starshot, a lightsail project backed by Stephen Hawking:

In order to prevent all that light frying the planet and the radio transmitter within seconds, a massive water-based cooling system would be required.

And hey, something like that sounds inconceivable to us humans, but we haven't even figured out cordless charging and hoverboards, so what do we know? The researchers say such a device is well within the laws of physics, so you've got to give them that.

The purpose of building such a colossal device would be two-fold—not only could it beam signals across vast areas of the Universe to other civilizations (like ours?), it could also propel probes or spaceships on extended journeys through interstellar space.
"We envision a beamer that emits the radio waves as a method of launching a light sail," Loeb told George Dvorsky at Gizmodo. "In the same way that a sailboat is pushed by wind, a lightsail is pushed by light and can reach up to the speed of light."

Of course, like the previous explanations for Fast Radio Bursts, this is all highly speculative, and Loeb isn't pretending that they have all the answers in their new proposal.

But he says science isn't a matter of what you believe, it's a matter of evidence, and it's always worth throwing a bunch of ideas out there to see where the data fits.

"Although the possibility that FRBs are produced by extragalactic civilizations is more speculative than an astrophysical origin, quantifying the requirements necessary for an artificial origin serves, at the very least, the important purpose of enabling astronomers to rule it out with future data," the team concludes.

The paper has been accepted for publication in an upcoming edition of Astrophysical Journal Letters, and you can read it for free now at arXiv.org.

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The past few years have been incredible for physics discoveries. Scientists spotted the Higgs boson, a particle they’d been hunting for almost 50 years, in 2012, and gravitational waves, which were theorized 100 years ago, in 2016. This year, they’re slated to take a picture of a black hole. So, thought some theorists, why not combine all of the craziest physics ideas into one, a physics turducken? What if we, say, try to spot the dark matter radiating off of black holes through their gravitational waves?

It’s really not that strange of an idea. Now that scientists have detected gravitational waves, ripples in spacetime spawned by the most violent physical events, they want to use their discovery to make real physics observations. They think they have a way to spot all-new particles that might make up dark matter, an unknown substance that accounts for over 80 percent of all of the gravity in the universe.

“The basic idea is that we’re trying to use black holes … the densest, most compact objects in the universe, to search for new kinds of particles,” Masha Baryakhtar, postdoctoral researcher at the Perimeter Institute for Theoretical Physics in Canada, said. Especially one particle: “The axion. People have been looking for it for 40 years.”

Black holes are the universe’s sinkholes, so strong that light can’t escape their pull once it’s entered. They’ve got such powerful gravitational fields that they produce gravitational waves when they collide with each other. Dark matter might not be made from particles (specks of mass and energy), but if it was, we might observe it as axions, particles around one quintillion (a billion billion) times lighter than an electron, hanging around black holes. Now that you understand all the terms, here’s how the theory works.

Baryakhtar and her teammates think that black holes are more than just bear traps for light, but nuclei at the center of a sort of gravitational atom. The axions would be the electrons, so to speak. If you already know about black holes, you know they have incredibly hot, high-energy discs of gas orbiting them, produced by the friction between particles accelerated by the black hole’s gravity. This theory ignores that stuff, since axions wouldn’t interact via friction.

Keeping with the atom analogy, the axions can jump around the black hole, gaining and losing energy the same way that electrons do. But electrons interact via electromagnetism, so they let out electromagnetic waves, or light waves. Axions interact via gravity, so they let out gravitational waves. But like I said earlier, axions are tiny. Unlike a tiny atom, the black hole in these “gravity atoms” rotates, supercharging the space around it and coaxing it into producing more axions. Despite the axion’s tiny mass, this so-called superradiance process could generate 10^80 axions, the same number of atoms in the entire universe, around a single black hole. Are you still with me? Crazy spinning blob makes lots of crazy stuff.

Craziest of all, we should be able to hear a gravitational wave hum from these axions moving around and releasing gravitational waves in our detectors, similar to the way you see spectral lines coming off of electrons in atoms in chemistry class. “You’d see this at a particular frequency which would be roughly twice the axion mass,” said Baryakhtar.

There are giant gravitational wave detectors scattered around the world; presently there’s one called LIGO (Laser Interferometer Gravitational Wave Observatory) in Washington State, another LIGO in Louisiana, and one called Virgo in Italy that are sensitive enough to detect gravitational waves, and with upgrades, to detect axions and prove their theory right. Scientists would essentially need to record data, play it back, and tune their analysis like a radio to pick up the signal at just the right frequency.

There are other ways the team thinks it could spot this superradiance effect, by measuring the spins in sets of colliding black holes. If black holes really do produce axions, scientists would see very few quickly-spinning black holes in collisions, since the superradiance effects would slow down some of the colliding black holes and create a visible effect in the data, according to the research published this month in the journal Physical Review D. The black hole spins would have a specific pattern which we should be able to spot in the gravitational wave detector data.

Other scientists were immediately excited about this paper. “I’m always super excited about new ways to detect my favorite pet particle, the axion! Also, SUPERRADIANCE!” Dr. Chanda Prescod-Weinstein, the University of Washington axion wrangler, said in an email. “It’s so cool, and I haven’t read a paper that talked about [superradiance] in years. So it was really fun to see superradiance and axions in one paper.”
There are a few drawbacks, as there are with any theory. These theorized black hole atoms would have to produce axions of a certain mass, but that mass isn’t an ideal one for the axion to be a dark matter particle, said Prescod-Weinstein. Plus, the second detection idea, the one that looks at the spin rate of colliding black holes, might not work. “They say [in the paper] that they don’t take into account the potential influence of another black hole” in the colliding pair, Dr. Lionel London, a research associate at Cardiff University School of Physics and Astronomy specializing in gravitational wave modeling, said. “If this does turn out to be a significant effect and they’re not including it, this could cast doubt on their results.” But there’s hope. “There’s good reason to believe the effect of a companion [black hole] won’t be large.”

When would we spot these kinds of events? As of now, the LIGO and Virgo gravitational wave detectors probably aren’t ready. “With the current sensitivity we’re on the edge” of detecting axions, said Baryakhtar. “But LIGO will continue improving their instruments and at design sensitivity we might be able to see as many as 1000s of these axion signals coming in,” she said. Thousands of hums from these black hole-atoms.

So, if you’ve gotten all the way to this point of the story and still don’t understand what’s going on, a recap: We’ve got these gravitational wave detectors that cost hundreds of millions of dollars each, that are good at spotting really crazy things going on in the universe. Theorists have come up with an interesting way to use them to solve one of the most important interstellar mysteries: What the heck is dark matter? As with most new ideas in theoretical physics, this is something cool to think about and isn’t ready for the big time … yet.

“I think that timescale is always a concern, but we’re just getting started with LIGO discoveries,” said Prescod-Weinstein. “So who knows what’s around the corner over the next 10 years.”

[Phys. Rev. D] SOURCE

 

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According to the Lambda Cold Dark Matter (Lambda-CDM) model, which is the current accepted standard for how the universe began and evolved, the ordinary matter we encounter every day only makes up around five percent of the universe's density, with dark matter comprising 27 percent, and the remaining 68 percent made up of dark energy, a so-far theoretical force driving the expansion of the universe. But a new study has questioned whether dark energy exists at all, citing computer simulations that found that by accounting for the changing structure of the cosmos, the gap in the theory, which dark energy was proposed to fill, vanishes.

Published in 1915, Einstein's general theory of relativity forms the basis for the accepted origin story of the universe, which says that the Big Bang kicked off the expansion of the universe about 13.8 billion years ago. The problem is that the equations at work are incredibly complicated—so physicists simplified parts of them to make them a bit more practical to work with. When models are then built up from these simplified versions, small holes can snowball into huge discrepancies.

"Einstein's equations of general relativity that describe the expansion of the universe are so complex mathematically that for a hundred years no solutions accounting for the effect of cosmic structures have been found," says Dr László Dobos, co-author of the new paper. "We know from very precise supernova observations that the universe is accelerating, but at the same time we rely on coarse approximations to Einstein's equations which may introduce serious side effects, such as the need for dark energy, in the models designed to fit the observational data."

Dark energy has never been directly observed, and can only be studied through its effects on other objects. Its properties and existence are still purely theoretical, making it a placeholder plug for holes in current models.

The mysterious force was first put forward as a driver of the universe's accelerated expansion in the 1990s, based on the observation of Type Ia supernovae. Sometimes called "standard candles," these bright spots are known to shine at a consistent peak brightness, and by measuring the brightness of that light by the time it reaches Earth, astronomers are able to figure out just how far away the object is.

This research was instrumental in spreading acceptance of the idea that dark energy is accelerating the expansion of the universe, and it earned the scientists involved the Nobel Prize in Physics in 2011. But other studies have questioned the validity of that conclusion, and some researchers are trying to develop a more accurate picture of the cosmos with software that can better handle all the wrinkles of the general theory of relativity.

According to the new study from Eötvös Loránd University in Hungary and the University of Hawaii, the discrepancy that dark energy was "invented" to fill might have arisen from the parts of the theory that were glossed over for the sake of simplicity. The researchers set up a computer simulation of how the universe formed, based on its large-scale structure. That structure apparently takes the form of "foam," where galaxies are found on the thin walls of each bubble, but large pockets in the middle are mostly devoid of both normal and dark matter.

The team simulated how gravity would affect matter in this structure and found that, rather than the universe expanding in a smooth, uniform manner, different parts of it would expand at different rates. Importantly, though, the overall average rate of expansion is still consistent with observations, and points to accelerated expansion. The end result is what the team calls the Avera model.

"The theory of general relativity is fundamental in understanding the way the universe evolves," says Dobos. "We do not question its validity; we question the validity of the approximate solutions. Our findings rely on a mathematical conjecture which permits the differential expansion of space, consistent with general relativity, and they show how the formation of complex structures of matter affects the expansion. These issues were previously swept under the rug but taking them into account can explain the acceleration without the need for dark energy."

If the research stands up to scrutiny, it could change the direction of the study of physics away from chasing the ghost of dark energy.

The research was published in the Monthly Notices of the Royal Astronomical Society, and an animation below compares the different models.

Source: Royal Astronomical Society

 

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Researchers have discovered a new and unexpected force that acts on nanoparticles in a vacuum, allowing them to be pushed around by pure nothingness.

Of course, quantum physics is beginning to make it clear that nothingness, as we like to think of it, doesn't actually exist—even vacuums are filled with tiny electromagnetic fluctuations. This new research is further proof that we're only beginning to understand the strange forces that are at work at the smallest level of the material world, by showing how nothingness can drive lateral motion.

So how can a vacuum carry force? One of the first things we learn in classical physics is that in a perfect vacuum—a place entirely devoid of matter—friction can't exist, because empty space can't exert a force on objects travelling through it.

But, in recent years, quantum physicists have shown that vacuums are actually filled by tiny electromagnetic fluctuations that can interfere with the activity of photons—particles of light—and produce a measurable force on objects.

This is called the Casimir effect, and it was first predicted by physicists back in 1948. Now, the new study has shown that this effect is even more powerful than they imagined.

Why does that matter? This Casimir effect might only be measurable on the quantum scale, but as we start engineering smaller and smaller technology, it's becoming clear that these quantum effects can greatly influence the overall products.

"These studies are important because we are developing nanotechnologies where we're getting into distances and sizes that are so small that these types of forces can dominate everything else," said lead researcher Alejandro Manjavacas from the University of New Mexico in the US.

"We know these Casimir forces exist, so, what we're trying to do is figure out the overall impact they have [on] very small particles."

To figure out how else Casimir forces could impact nanoparticles, the team looked at what happened with nanoparticles rotating near a flat surface in a vacuum.

What they found was that the Casimir effect could actually push those nanoparticles laterally—even if they weren't touching the surface.

That's a little strange, but imagine it like this—you have a tiny sphere rotating over a surface that's constantly being bombarded with photons. While the photons slow down the rotation of the sphere, they also cause the sphere to move in a lateral direction.

In the classical physics world, friction would be needed between the sphere and the surface to achieve this lateral motion, but the quantum world doesn't follow the same results, and so it can be pushed across a surface even when it's not touching it.

"The nanoparticle experiences a lateral force as if it were in contact with the surface, even though is actually separated from it," said Manjavacas.

"It's a strange reaction but one that may prove to have significant impact for engineers."

All of this might sound a little obscure, but it could play an important role in figuring out how to develop smaller and smaller technology, as well as devices such as quantum computers.

Intriguingly, the researchers show that they could control the direction of the force by changing the distance between the particle and the surface, which could one day come in handy for engineers and researchers who are constantly looking for better ways to manipulate matter on the nano-scale.

The findings now need to be replicated and verified by other teams. But the fact that we now have evidence of an intriguing new force that could be used to direct nanoparticles within nothingness is pretty exciting—and suggests we're one step closer to understanding the weird forces at work in the quantum world.

The research has been published in Physical Review Letters.

SOURCE

 

[Stormer0628]

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Physicists Create Superfluid with Negative Mass​

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In one of the labs on the sixth floor of the Webster Hall at University of Washington, physicists have managed a very rare feat: they’ve made a fluid with negative mass.

When scientists say something has negative mass, they don’t mean it literally. What they mean is that when an object with a negative mass is being pushed, it moves in the opposite direction, towards you, instead of the direction of the force. That’s totally unrelatable to most people without a PhD in physics but this can happen, as the team from the University of Washington elegantly demonstrated. And yes, Newton’s Second Law of Motion is still in place.

“Newton’s laws dictate that objects accelerate in proportion to the applied force. An object’s mass is generally positive, and the acceleration is thus in the same direction as the force. In some systems, however, one finds that objects can accelerate against the applied force, realizing a negative effective mass,” the researchers wrote in their paper published in the Physical Review Letters.​

Michael Forbes, an assistant professor of physics and astronomy at the University of Washington, and colleagues, cooled rubidium atoms almost to absolute zero (−273.15 °C; −459.67 °F). At those temperatures, the gas is in an exotic state of matter called Bose–Einstein condensate (BEC). BEC was first predicted in the 1920s by Albert Einstein and Indian physicist Satyendra Bose but it wasn’t until very late in 1995 that scientists were able to produce the necessary conditions for this extreme state of matter to occur. At room temperature, atoms are incredibly fast and behave akin to billiard balls, bouncing off each other when they interact. As you lower the temperature (remember temperature reflects atomic agitation or vibration), atoms and molecules move slower. Eventually, once you get to about 0.000001 degrees above absolute zero, atoms become so densely packed they behave like one super atom, acting in unison. This is the domain of quantum mechanics so prepared for a lot of weirdness.

Essentially, BEC particles behave like waves, moving in unison as a superfluid which is a fluid that flows without losing energy. Superfluids are so ‘out of this world’ that they can escape containers by themselves, climbing walls. Because a superfluid loses all viscosity, it can not be contained and thus can even leak through a glass beaker, as shown below (superfluid helium).

To create the necessary conditions for the superfluid to form, the rubidium atoms were cooled by lasers. That sounds counter-intuitive given lasers usually heat stuff but scientists have been using lasers for cooling purposes for some years. The kind of lasers used for cooling fire at a specific angle and frequency. Typically multiple lasers are used. As a result of this clever tweaking photons actually end up snatching energy from its target instead of releasing it, and it’s all done by literally pushing the atoms. More about this in this amazing demonstration performed by Veritasium.

Since the rubidium atoms are cooled just a hair above absolute zero, they’re almost still. The area the almost motionless atoms are confined to is akin to a bowl measuring less than a hundred microns across. When a second set of lasers was fired on this ‘bowl’, the atoms were kicked back and forth changing the way the spin (spin-orbit coupling). When the rubidium atoms are allowed to flow out of the bowl fast enough, the superfluid behaves as it had negative mass.

“Once you push, it accelerates backwards,” said Forbes in a statement. “It looks like the rubidium hits an invisible wall.”​

This isn’t the first time scientists have observed negative mass in action but the technique designed by the WSU researchers avoids some of the underlying defects encountered in previous attempts to understand negative mass. The same technique could be used to study analogous physics in astrophysics, like neutron stars, but also black holes and dark energy.

“What’s a first here is the exquisite control we have over the nature of this negative mass, without any other complications,” says Forbes. “It provides another environment to study a fundamental phenomenon that is very peculiar.”​

SOURCE

 

[Stormer0628]

Dark matter 'bridge' holding galaxies together
has been captured for the first time

The first image of a dark matter "bridge,” believed to form the links between galaxies, has been captured by astrophysicists in Canada.

Researchers at the University of Waterloo used a technique known as weak gravitational lensing to create a composite image of the bridge. Gravitational lensing is an effect that causes the images of distant galaxies to warp slightly under the influence of an unseen mass, such as a planet, a black hole, or in this case, dark matter.

Their composite image was made up of a combination of combined lensing images taken of more than 23,000 galaxy pairs, spotted 4.5 billion light-years away. This effect was measured from a multi-year sky survey at the Canada-France-Hawaii Telescope.

These results show that the dark matter filament bridge is strongest between systems less than 40 million light years apart, and confirms predictions that galaxies across the Universe are tied together through a cosmic web of the elusive substance.

Dark matter is known as "dark" because it doesn't shine, absorb or reflect light, which has traditionally made it largely undetectable, except through gravity and gravitational lensing. Evidence for the existence of this form of matter comes, among other things, from the astrophysical observation of galaxies, which rotate far too rapidly to be held together only by the gravitational pull of the visible matter.

Astrophysics has long proposed the Universe's web of stars and galaxies is supported by a "cosmic scaffolding" made up of fine threads of this invisible dark matter. These threadlike strands formed just after the Big Bang when denser portions of the Universe drew in dark matter until it collapsed and formed flat disks, which featured fine filaments of dark matter at their joins. At the cross-section of these filaments, galaxies formed.

"For decades, researchers have been predicting the existence of dark matter filaments between galaxies that act like a web-like superstructure connecting galaxies together," said Mike Hudson, a professor of astronomy at the University of Waterloo in the journal Monthly Notices of the Royal Astronomical Society. "This image moves us beyond predictions to something we can see and measure."

"By using this technique, we're not only able to see that these dark matter filaments in the Universe exist, we're able to see the extent to which these filaments connect galaxies together," said coauthor Seth Epps.


====================

SOURCE

See also:

Mystery of the missing mass: huge cloud of hydrogen is to blame for holes in the Milky Way

Does Dark Matter Exist, Or Is Gravity Wrong?

 

[Stormer0628]

While at first glance the crackle of electricity and invisible tug of magnetism seem to be fairly different things, for about 150 years scientists have accepted that they're both fundamentally aspects of the same phenomenon.

But there has been a mystery attached to this electromagnetic duality – if electric fields have electric charges, why don't magnetic fields have something similar like a magnetic charge? Scientists now think they might have an answer.

New research led by scientists from Louisiana State University suggests that gravity mucks up the symmetry that would otherwise require magnetic charges – or magnetic monopoles – to exist.

"Gravity spoils the symmetry regardless of whether magnetic monopoles exist or not," said team leader Ivan Agullo. "This is shocking."

"The bottom line is that the symmetry cannot exist in our Universe at the fundamental level because gravity is everywhere."

All this talk of magnetic monopoles and symmetry can get a little confusing, so let's take a step back for a second and revisit the basics.

Back in the mid-19th century, an awkward but brilliant Scottish scientist by the name of James Clerk Maxwell applied a bunch of existing mathematics to the experimental work of another great mind, Michael Faraday.

While Faraday was making magnets spin with electrical currents, and creating electrical currents by making magnets spin, Maxwell was crunching the numbers to show that magnetic and electric fields – the lines of arrows your high school physics teacher made you draw around bar magnets – could be swapped, and nobody would be any the wiser.

This describes a feature of the Universe called symmetry – some things look the same no matter how you rotate them, when you observe them, or where you stand.

The thing is, this electromagnetic symmetry only works if you ignore currents and charges; electrical fields are made up of points of force called electric charges that exist along a vector (in other words, the charge has a flow), but in spite of having a similar 'north-south/positive-negative' type flow, magnetic fields don't have magnetic charges, ruining the symmetry.

And if there's one thing theoretical physicists and mathematicians hate, it's the ugliness of ruined symmetry!

None of this is for want of looking, either; theoretical physicist Paul Dirac believed if a magnetic monopole could be found it would help explain why the electric charge existed as a point like it did.

Things that look like monopoles have been created under certain laboratory conditions, using super-chilled atoms, but something that behaves in the manner of a magnetic monopole isn't necessarily the same thing, meaning we still don't have empirical evidence that they exist.

And now the latest study suggests their existence is impossible. To better understand how the researchers came to the conclusion that gravity was responsible for the break in the electromagnetic duality, it helps to throw another phenomenon into the mix – light.

Light is made up of tiny particles called photons, which is more or less a unit of information in the electromagnetic field carrying the electromagnetic force.

Different frequencies of this quantum of electromagnetism are responsible for different colors, not to mention microwaves, radio waves, and X-rays.

Photons are a type of particle called a boson, which are defined by the fact two or more identical particles can occupy the same quantum state.

There are other particles called fermions, which include electrons and the quarks that make up protons and neutrons, that can't do this, which also helps explain why they can't overlap one another in physical space.

So the researchers looked at how gravity interrupts other symmetries, including those involving fermions, and found a way to rework the fundamental theory explaining the electromagnetic field so they applied to photons instead.

The result exposed evidence that magnetic monopoles might not be hiding - since gravity permeates the entire Universe, the broken symmetry between electric charges and magnetic monopoles exists on a fundamental level.

"We have been able to write the theory of the electromagnetic field in a way that very much resembles the theory of fermions, and prove this absence of symmetry by using powerful techniques that were developed for fermions," said Agullo.

Now that doesn't rule out magnetic monopoles as such, but it does remove symmetry as a reason for looking.

If the new study supported, this is pretty big news not just for magnetic monopole hunters; astrophysicists will need to take it into account when studying the echoes of light from the early Universe.

The photons making up the radiation from the Big Bang – also called the Cosmic Microwave Background – carry important clues about the nature of the Universe they pass through.

So far, astrophysicists haven't worried about the effects of gravity on the polarization of photons as they whiz through space, but that's purely on the assumption that there is such a thing as electromagnetic symmetry.

The next step is for researchers to see if the broken symmetry means the polarization of light has changed as the Universe aged, and if it tells us anything new about our cosmic history.

This research was published in Physical Review Letters.

===========================
SEE ALSO:
Gravity Might Be Messing With The Fundamental Laws Of Electromagnetism

 

[Stormer0628]

The Cold Spot is an area of the cosmic microwave background with a lower
temperature than its surroundings. On this map created by the Planck satellite,
warmer CMB temperatures appear redder and cooler temperatures appear bluer.​

The cosmic microwave background (CMB) is the fingerprint of the Big Bang. This remnant radiation occurs throughout the sky, with a temperature 2.73 degrees above absolute zero (about -454 degrees Fahrenheit, or -270 Celsius). While the CMB is fairly uniform, it does have some (very small) fluctuations. These fluctuations hold the key to details about both the Big Bang and the very early lifetime of the universe. Now, researchers have determined that a Cold Spot, an area of the CMB 0.00015 degrees below its surroundings, isn’t due to a lack of matter in the area, as previously thought. Ruling out this mundane possibility leaves open the door for more exotic explanations of the Cold Spot.

In a study led by Ruari Mackenzi and Tom Shanks at Durham University's Centre for Extragalactic Astronomy and published in the Monthly Notices of the Royal Astronomical Society, the group explores the possibility that a “supervoid” of space — an area lacking a significant number of galaxies and other matter — is responsible for the Cold Spot. Both regular matter and dark matter tend to clump together in space, forming structures such as clusters and walls in some areas, while leaving voids without much material in others. This effect is exacerbated by the expansion of the universe, and causes the CMB coming from the direction of a void to look different than CMB radiation that must travel through areas of space more densely populated on its way to Earth.

Previous studies used a technique called photometric redshift to measure the distance of galaxies in the direction of the Cold Spot. This technique uses a galaxy’s perceived colors to estimate how far away it is, because more distant galaxies appear redder than their nearby counterparts. However, photometric redshifts often have significant uncertainties. Mackenzi and Shanks’ team instead used spectroscopic redshifts, which break apart the light from an object and are much more accurate, to determine the distance to 7,000 galaxies in the direction of the Cold Spot with data from the Anglo-Australian Telescope.

The more accurate data revealed, however, that there is no supervoid in the direction of the Cold Spot. Instead, that area of the sky looks much like the rest, with clusters of galaxies and smaller voids between them. When the sky in the direction of the Cold Spot was compared with another area of the sky without a cooler CMB behind it, no significant difference was found. “The voids we have detected cannot explain the Cold Spot under standard cosmology,” said MacKenzie in a press release detailing the results.

What does this mean? Standard cosmology is the model we currently use to describe the universe around us. Observations that challenge this model must be examined carefully, but can be used to further refine our model to ensure it’s correct.

Even without a supervoid in the way, the team estimates a likelihood that the Cold Spot appeared by random chance as 1 in 50. According to Shanks, “This means we can't entirely rule out that the Spot is caused by an unlikely fluctuation explained by the standard model. But if that isn't the answer, then there are more exotic explanations.”

Such exotic explanations, he says, include “a collision between our universe and another bubble universe. If further, more detailed, analysis of CMB data proves this to be the case then the Cold Spot might be taken as the first evidence for the multiverse – and billions of other universes may exist like our own.”

The multiverse describes a set of infinite universes, which includes the one in which we live. To date, no evidence has been found that the multiverse is more than science fiction, but researchers are continually pushing the boundaries of the observable universe to determine whether this concept is fact or fiction. While at the moment the Cold Spot is certainly not definitive evidence of a multiverse, it does indicate a problem in our standard cosmological model that may need addressing if the cause of the temperature fluctuation in this area remains unclear.


SOURCE

 

[Stormer0628]

For the first time, astronomers have spotted a massive, inactive galaxy from when the Universe was only around 1.7 billion years old, and no one can explain how it ended up there.

Our current understanding of galaxy formation states that all of the galaxies that existed back then should have been tiny and low-mass, and busy forming stars. Instead, this dead behemoth was already five times more massive than our Milky Way is now, all condensed into an area 12 times smaller, and had long finished its peak star formation.

If the discovery is verified by other teams, it means scientists will need to rethink the way galaxies form, and overhaul our assumptions about what happened in the first few billion years after the Big Bang.

It also suggests that there are plenty of surprises yet to be found at the beginning of our Universe.

"This discovery sets a new record for the earliest massive red galaxy," said lead researcher Karl Glazebrook from Swinburne University of Technology in Australia.

"It is an incredibly rare find that poses a new challenge to galaxy evolution models to accommodate the existence of such galaxies much earlier in the Universe."

While there are still a lot of unknowns about how and when galaxies start and stop forming stars, our best models assume that it happened a while after the origin of the Universe—meaning it would have been at least 3 billion years after the Big Bang before dead galaxies such as this 'red nugget' would have appeared.

In the time before that, research suggests that most galaxies would have been low-mass and busy making stars. For example, astrophysicists predict that 1.7 billion years after the Big Bang, our own Milky Way galaxy would have been a "messy little dwarf galaxy with just 1/50th of its mass today", as the video above explains.

But this new galaxy, known as ZF-COSMOS-20115, contradicts that model entirely.

The new study suggests this galaxy had formed all of its stars (three times more stars than in our Milky Way today) during a rapid star-burst event that occurred relatively soon after the Big Bang, and by 1.7 billion years into the Universe's history, it was already done.

That makes it what's known as a quiescent or 'red and dead' galaxy, which is common to see around the Universe today, but no one had expected one to exist back then.

"This huge galaxy formed like a firecracker in less than 100 million years, right at the start of cosmic history," said Glazebrook.

"It quickly made a monstrous object, then just as suddenly it quenched and turned itself off. As to how it did this we can only speculate. This fast life and death so early in the Universe is not predicted by our modern galaxy formation theories."

Researchers had previously found hints of these strange, early maturing galaxies, but this is the first time researchers have properly detected on.

To peer so far back in time, the researchers used the giant W M Keck telescopes in Hawaii. They were looking for emissions at near-infrared wavelengths, to give them information on the presence of old stars and a lack of active star formation in old galaxies.

When they first spotted ZF-COSMOS-20115, they didn't think it could be real, Glazebrook told Gizmodo.

"We used the most powerful telescope in the world, but we still needed to stare at this galaxy for more than two nights to reveal its remarkable nature," said one of the researchers, Vy Tran from Texas A&M University.

What's needed now is follow-up observations using sub-millimeter wave telescopes—something that the James Webb Space Telescope, which is set to launch in 2018, will be able to assist with from outside the interference of Earth's atmosphere.

"Sub-millimeter waves are emitted by the hot dust which blocks other light and will tell us when these firecrackers exploded and how big a role they played in developing the primordial universe," explains one of the team, Corentin Schreiber from Leiden University in the Netherlands.

Until then, it's anyone's guess how this giant dead galaxy came about so early in the timeline of our Universe, and you can bet that mystery is going to be keeping astrophysicists up at night for the months to come.

The research has been published in Nature.

SOURCE

 

[Geroll]

Posible po ba ang law of entropy sa begining? bago ang quantum flactuation. paano po un sir

 

[WhoSay29]

EH DI WOW!!!

 

[Stormer0628]

Posible po ba ang law of entropy sa begining? bago ang quantum flactuation. paano po un sir

Interesting, interesting question. Here's what I think:

If you think of quantum fluctuations in a classical way, i.e., of pure space, then we cannot have entropy.

On the other hand, if you think of quantum fluctuations as probabilistic distribution of virtual annihilations, for example, then you can derive a formula for such entropy generated by the quantum fluctuations—and then you can imagine quantum fluctuations and entropy go hand in hand at the first critical moments of the emergence of the universe.

For an interesting read, note the following articles:

The quantum Thermodynamics Revolution (Quanta Magazine)
Boltzmann Brain (Boltzmann is of course that tragic figure of the whole entropy theory.)
Can quantum vacuum carry entropy?

 

[Stormer0628]

Physicists Just Generated a Particle That Acts as Its Own Antiparticle
Matter and antimatter in a single package.

​

It's been exactly 80 years since the theoretical physicist Ettore Majorana predicted that there were neutrally charged particles that were indistinguishable from their own antiparticle. None have been spotted in the wild, and not for want of looking.

Physicists now have the next best thing—a particle-like system that behaves just like the kind of matter Majorana predicted. Not only does it provide experimental evidence of these unique kinds of particles, but it could have applications in the future of quantum computing.

Researchers from Stanford and the University of California made the discovery by forcing electrons to flow in opposite directions along the edges of a sandwich of superconducting materials to collectively give rise to pairs of what are known as quasiparticles.

Don't let the fact quasiparticles aren't bona-fide particles fool you; they still count as far as evidence of certain phenomena goes.

Applying a magnetic field to these particle-like couples as they zipped along caused them to slow down and change direction in distinct stages, a feature that was exploited to spot a kind of behavior that was a signature of Majorana particles.

"Our team predicted exactly where to find the Majorana fermion and what to look for as its 'smoking gun' experimental signature," says Stanford researcher Shoucheng Zhang.

In homage they named their discoveries "Angel particles", after the Dan Brown thriller Angels and Demons which features a bomb made of antimatter.

If you've ever watched a sci-fi movie (or read a Dan Brown novel), you might have come across this antimatter thing.

In simple terms, for every type of fundamental particle in the Universe there is the equivalent of an evil twin complete with an opposing charge; the negatively charged electron, for example, has a positively charged positron as its antiparticle.

Bringing the two particles together makes them cancel out each other's existence, leaving behind nothing but an intense burst of gamma radiation.

It's that huge pile of radiation that has served as imagination-fuel for all kinds of futuristic space-ship engines and hypothetical weapons of mass destruction.

Particles and antiparticles can go the other way as well, being born together in a concentration of energy such as the ones inside particle colliders, which is how physicists study them today.

Majorana figured there must be particles that are their own antiparticle within the fundamental class of matter known as fermions, which includes things like electrons, neutrinos, and the quarks making up protons and neutrons.

These Majorana particles could also be created as a pair, but would be identical and wouldn't wipe each other out if brought together again.

Photons are good examples of being their own antiparticles, but they aren't fermions.

Neutrons, on the other hand, would be great candidates, since they're already neutral. Unfortunately if neutrons are brought together with anti-neutrons, their opposing group of quarks still annihilate each other.

Another interesting candidate are the tiny, near-massless bits of matter called neutrinos.

Given the difficulty in detecting these ghostly particles, the jury is still out on whether they qualify as Majorana fermions, and will be for some time yet.

It could turn out that such particles just don't exist in the Universe, at least not outside of experiments like these.

That's not to say these results have nothing to contribute to the search of 'real' Majorana particles.

"Where it gets more interesting is that analogies in physics have proved very powerful. And even if they are very different beasts, different processes, maybe we can use one to understand the other. Maybe we will discover something that is interesting for us, too," says researcher Giorgio Gratta, also from Stanford.

Even if the results aren't shocking, the engineering of the experiment itself has been of interest to physicists.

The technology could be used in the future as a way to reduce the risk of a particle in a quantum computer losing its information. A back-up quasi-antiparticle could be just the thing to make the system more robust.

Nobel laureate Frank Wilczek, who wasn't involved in the research, praised the team's ingenuity.

"It's not fundamentally surprising, because physicists have thought for a long time that Majorana fermions could arise out of the types of materials used in this experiment," says Wilczek.

"But they put together several elements that had never been put together before, and engineering things so this new kind of quantum particle can be observed in a clean, robust way is a real milestone."

This research was published in Science.

SOURCE

 

[Stormer0628]

Evidence mounts that neutrinos are the key to the universe's existence

​

New experimental results show a difference in the way neutrinos and antineutrinos behave, which could explain why matter persists over antimatter.

The results, from the T2K experiment in Japan, show that the degree to which neutrinos change their type differs from their antineutrino counterparts. This is important because if all types of matter and antimatter behave the same way, they should have obliterated each other shortly after the Big Bang.

So far, when scientists have looked at matter-antimatter pairs of particles, no differences have been large enough to explain why the universe is made up of matter – and exists – rather than being annihilated by antimatter.

Neutrinos and antineutrinos are one of the last matter-antimatter pairs to be investigated since they are difficult to produce and measure, but their strange behavior hints that they could be the key to the mystery.

Flavor change

Neutrinos (and antineutrinos) come in three 'flavors' of tau, muon and electron, each of which can spontaneously change into the other as the neutrinos travel over long distances.

The latest results, announced today by a team of researchers including physicists from Imperial College London, show more muon neutrinos changing into electron neutrinos than muon antineutrinos changing into electron antineutrinos.

This difference in muon-to-electron changing behavior between neutrinos and antineutrinos means they would have different properties, which could have prevented them from destroying each other and allow the universe to exist.

To explore the (anti)neutrino flavor changes, known as oscillations, the T2K experiment fires a beam of (anti)neutrinos from the J-PARC laboratory at Tokai Village on the eastern coast of Japan.

It then detects them at the Super-Kamiokande detector, 295 km away in the mountains of the north-western part of the country. Here, the scientists look to see if the (anti)neutrinos at the end of the beam matched those emitted at the start.

Very intriguing

The latest results were concluded from relatively few data points, meaning there is still a one in 20 chance that the results are due to random chance, rather than a true difference in behavior. However, the result is still exciting for the scientists involved.

Dr Morgan Wascko, international co-spokesperson for the T2K experiment from the Department of Physics at Imperial said: "This is an important first step towards potentially solving one of the biggest mysteries in science.

"T2K is the first experiment that is able to study neutrino and antineutrino oscillation under the same conditions, and the disparity we have observed is, while not yet statistically significant, very intriguing."

Dr Yoshi Uchida, also from the Department of Physics at Imperial and a principal investigator at T2K, added: "More data is needed to prove conclusively that neutrinos and antineutrinos behave differently, but this result is an indication that neutrinos will continue to provide breakthroughs in our understanding of the universe.

Upgrades to the equipment that produces (anti)neutrinos, as well as to the detector that measures them, are expected to add more data within the next decade, and determine whether the difference is in fact real.


SOURCE

 

[Stormer0628]

Exclusive: We may have detected a new kind of gravitational wave

Have we detected a new flavor of gravitational wave? Speculation is swelling that researchers have spotted the subtle warping of the fabric of space resulting from the cataclysmic collision of two neutron stars.

Now optical telescopes—including the Hubble Space Telescope—are scrambling to point at the source of the possible wave: an elliptical galaxy hundreds of millions of light years away.

Gravitational waves are markers of the most violent events in our universe, generated when dense objects such as black holes or neutron stars crash together with tremendous energy. Two experiments—LIGO in the US and VIRGO in Europe – set out to detect minuscule changes in the path of laser beams caused by passing gravitational waves.

LIGO has discovered three gravitational wave sources to date, all of them colliding black holes. The two observatories have been coordinating data collection since November, increasing their sensitivity. That collaboration may be about to pay off.

Over the weekend, astronomer J. Craig Wheeler of the University of Texas at Austin launched speculation over a potential new LIGO detection by tweeting: “New LIGO. Source with optical counterpart. Blow your sox off!”

By optical counterpart, he probably means that astronomers could observe light emitted by the gravitational wave source. This suggests the source is neutron stars as, unlike black holes, they can be seen in visible wavelengths. LIGO researchers have long-anticipated this possibility, setting up partnerships with optical observatories to rapidly follow-up on potential signals prior to formally announcing a discovery.

LIGO spokesperson David Shoemaker dodged confirming or denying the rumors, saying only “A very exciting O2 Observing run is drawing to a close August 25. We look forward to posting a top-level update at that time.”

Speculation is focused on NGC 4993, a galaxy about 130 million light years away in the Hydra constellation. Within it, a pair of neutron stars are entwined in a deadly dance. While astronomers are staying silent on whether they are engaged in optical follow-ups to a potential gravitational wave detection, last night the Hubble Space Telescope turned its focus to a binary neutron star merger within the galaxy. A publicly available image of this merger was later deleted.

If LIGO and VIRGO really have picked up the gravitational waves of colliding neutron stars, it might explain why collaborator Andy Howell mused earlier in the week, “Tonight is one of those nights where watching the astronomical observations roll in is better than any story any human has ever told.”

SOURCE

 

[TitoG]

Re: Making Universe Out of Nothing At All

kung naniniwala ka sa bible malinaw ang sinasabi...maliban nalang kung di ka naniniwala sa Dios...

Hebrews 3:4 "Of course, every house is constructed by someone, but the one who constructed all things is God."

View attachment 321565

 

[Stormer0628]

Re: Making Universe Out of Nothing At All

.....

New Wave of Physics
Electrons Flow Like Liquid and Are Insanely Superconductive

​

Electrons have been caught flowing through graphene like a liquid, reaching limits physicists thought were fundamentally impossible.

This type of conductance is known as superballistic flow, and this new experiment suggests it could revolutionize the way we conduct electricity.

If that's not crazy enough, the super-fast flows actually occur as a result of electrons bouncing off each other, something that high school physics tells us should slow conductivity down.

So what's going on here? For decades, scientists had speculated that, under some circumstances, electrons might stop behaving as individuals and collide so often that they actually begin to flow like a viscous fluid with all kinds of unique properties.

But it was only last year that researchers confirmed the phenomenon, showing for the first time that, even at room temperature, electrons within graphene could act as a fluid 100 times more viscous than honey—something the researchers referred to as "quantum weirdness arising from [electrons'] collective motion".

Now the same team, led by Sir Andre Geim—the University of Manchester physicist who won the 2010 Nobel Prize for his work characterizing graphene - has shown that this liquid electron phenomenon is even crazier than we thought.

By unlocking this fluid-like behavior, the researchers were able to observe electrons in graphene smashing a fundamental limit for electrons in a normal metal, known as Landauer's ballistic limit.

This is some of the first experimental confirmation demonstrating just how powerful a whole new type of physics could be, and, importantly, it also suggests we could be on the verge of an entirely new way to shuttle electricity through materials with close to zero resistance.

Right now, that's something that superconductors can achieve, but the ability only emerges at super-chill temperatures below 5.8 K (-267°C or -450°F).

But in the latest study, the researchers were able to observe this so-called superballistic flow within graphene at the relatively warm temperature of 150 K (-123°C and -190°F).

In fact, resistance actually decreased as temperature increased, the opposite of what you'd expect to happen.

For now this is just one study, and independent teams will need to verify the University of Manchester results. But finding a way to more efficiently conduct electricity at higher temperatures is one of the 'Holy Grails' of physics, as it would pave the way for things like super-efficient computers, or electricity grids that don't lose 7 percent of their energy as heat.

That's exciting enough, but for the physics community, the real breakthrough here is the fact that this is one of the first detailed explorations of this new liquid-like electron behavior—and it suggests we're only just scratching the surface of how weird it really is.

What's so strange is that this type of electron flow is counterintuitive to everything else we know about conductance—which is that the more electrons scatter, the less conductive a material is.

That's why graphene is already many times more conductive than, say, copper—its neat 2D structure has far fewer imperfections than regular metals, so electrons traveling through it scatter less and move faster, which is known as ballistic flow.

But the opposite occurs when electrons begin to work together and behave like a fluid - something that this latest study shows us is capable of unlocking superballistic flow.

"We know from school that additional disorder always creates extra electrical resistance," said Geim.

"In our case, disorder induced by electron scattering actually reduces rather than increase resistance."

"This is unique and quite counterintuitive: electrons when make up a liquid start propagating faster than if they were free, like in vacuum".

How does it work? Instead of increasing resistance, sometimes when electrons collide with each other, they can actually start to work together and ease the flow of current.

If you think of the crystals within graphene as a channel that electrons need to flow through, electrons slow down the most when they bounce off the edges of the channel, losing momentum.

In this fluid behavior, however, some electrons remain near the edge, effectively buffering other electrons from colliding with those regions and slowing down.

As a result, some electrons become superballistic as they are guided through the channels within graphene, by bouncing off their friends.This is the same thing that happens in a river—the current is fastest in the middle.

Sir Geim and his team have called this new physical quantity 'viscous conductance'. And seeing as this is one of the first studies into its abilities and it's already breaking through major physical limits, we're pretty sure you're going to be hearing a whole lot more about it.

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