Mysterious results in an experiment may be due to dark energy

Shane McGlaun - Sep 16, 2021, 

One of the most mysterious subjects that scientists around the world are studying is called dark energy. Scientists believe dark energy is the mysterious force that leads to acceleration in the universe. A team of researchers from the University of Cambridge has published a study that suggests unexplained results obtained from an experiment conducted in Italy called XENON1T could have been caused by dark energy.

Interestingly, the experiment was designed to detect dark matter, but Cambridge scientists believe dark energy could account for the mysterious and unexplained results from the experiment. In the study, physical models were constructed in an attempt to explain the experiment results. Study researchers believe the experiment results could have been caused by dark energy particles in a region of the sun dominated by strong magnetic fields.

Unfortunately, additional experiments will be required to confirm their theory. Nevertheless, scientists are excited at the possibility of the discovery of dark energy. Currently, estimates predict that everything we can see with our eyes in the universe accounts for less than five percent of what’s there. Most of the material in the universe is dark, and theories suggest 27 percent of the entire universe is dark matter.

Dark matter is described as a force that holds galaxies and the cosmos itself together. Scientists also believe that 68 percent of the universe is made up of dark energy causing the universe to expand and accelerate. Since both dark matter and dark energy are invisible, little is known about them.

The presence of dark matter was first theorized in the 1920s, but dark energy wasn’t discovered until 1998. Scientists say that while the experiment was intended to detect dark matter, detecting dark energy is even more difficult. The study comes after the XEON1T experiment discovered an unexpected signal about a year ago that was higher than the expected background. Researchers on this study decided to explore a model where the unexpected signal was attributed to dark energy rather than dark matter. Scientists admit they are still far from understanding dark energy, and additional experiments are needed.

Have we detected dark energy? Scientists say it's a possibility

by University of Cambridge

Credit: CC0 Public Domain

A new study, led by researchers at the University of Cambridge and reported in the journal Physical Review D, suggests that some unexplained results from the XENON1T experiment in Italy may have been caused by dark energy, and not the dark matter the experiment was designed to detect.

They constructed a physical model to help explain the results, which may have originated from dark energy particles produced in a region of the Sun with strong magnetic fields, although future experiments will be required to confirm this explanation. The researchers say their study could be an important step toward the direct detection of dark energy.

Everything our eyes can see in the skies and in our everyday world—from tiny moons to massive galaxies, from ants to blue whales—makes up less than five percent of the universe. The rest is dark. About 27% is dark matter—the invisible force holding galaxies and the cosmic web together—while 68% is dark energy, which causes the universe to expand at an accelerated rate.

"Despite both components being invisible, we know a lot more about dark matter, since its existence was suggested as early as the 1920s, while dark energy wasn't discovered until 1998," said Dr. Sunny Vagnozzi from Cambridge's Kavli Institute for Cosmology, the paper's first author. "Large-scale experiments like XENON1T have been designed to directly detect dark matter, by searching for signs of dark matter 'hitting' ordinary matter, but dark energy is even more elusive."

To detect dark energy, scientists generally look for gravitational interactions: the way gravity pulls objects around. And on the largest scales, the gravitational effect of dark energy is repulsive, pulling things away from each other and making the Universe's expansion accelerate.

About a year ago, the XENON1T experiment reported an unexpected signal, or excess, over the expected background. "These sorts of excesses are often flukes, but once in a while they can also lead to fundamental discoveries," said Dr. Luca Visinelli, a researcher at Frascati National Laboratories in Italy, a co-author of the study. "We explored a model in which this signal could be attributable to dark energy, rather than the dark matter the experiment was originally devised to detect."

At the time, the most popular explanation for the excess were axions—hypothetical, extremely light particles—produced in the Sun. However, this explanation does not stand up to observations, since the amount of axions that would be required to explain the XENON1T signal would drastically alter the evolution of stars much heavier than the Sun, in conflict with what we observe.

We are far from fully understanding what dark energy is, but most physical models for dark energy would lead to the existence of a so-called fifth force. There are four fundamental forces in the universe, and anything that can't be explained by one of these forces is sometimes referred to as the result of an unknown fifth force.

However, we know that Einstein's theory of gravity works extremely well in the local universe. Therefore, any fifth force associated to dark energy is unwanted and must be 'hidden' or 'screened' when it comes to small scales, and can only operate on the largest scales where Einstein's theory of gravity fails to explain the acceleration of the Universe. To hide the fifth force, many models for dark energy are equipped with so-called screening mechanisms, which dynamically hide the fifth force.

Vagnozzi and his co-authors constructed a physical model, which used a type of screening mechanism known as chameleon screening, to show that dark energy particles produced in the Sun's strong magnetic fields could explain the XENON1T excess.

"Our chameleon screening shuts down the production of dark energy particles in very dense objects, avoiding the problems faced by solar axions," said Vagnozzi. "It also allows us to decouple what happens in the local very dense Universe from what happens on the largest scales, where the density is extremely low."

The researchers used their model to show what would happen in the detector if the dark energy was produced in a particular region of the Sun, called the tachocline, where the magnetic fields are particularly strong.

"It was really surprising that this excess could in principle have been caused by dark energy rather than dark matter," said Vagnozzi. "When things click together like that, it's really special."

Their calculations suggest that experiments like XENON1T, which are designed to detect dark matter, could also be used to detect dark energy. However, the original excess still needs to be convincingly confirmed. "We first need to know that this wasn't simply a fluke," said Visinelli. "If XENON1T actually saw something, you'd expect to see a similar excess again in future experiments, but this time with a much stronger signal."

If the excess was the result of dark energy, upcoming upgrades to the XENON1T experiment, as well as experiments pursuing similar goals such as LUX-Zeplin and PandaX-xT, mean that it could be possible to directly detect dark energy within the next decade.

New study sows doubt about the composition of 70 percent of our universe

More information: Sunny Vagnozzi et al, Direct detection of dark energy: The XENON1T excess and future prospects, Physical Review D (2021). DOI: 10.1103/PhysRevD.104.063023

Journal information: Physical Review D 

Provided by University of Cambridge 

Dark Energy Could Be Responsible for Mysterious Experiment Signals, Researchers Say

What if a bunch of liquid xenon under the Apennine Mountains found 68% of the universe?

By
Isaac Schultz
Friday 3:03PM

The XENON1T Time Projection Chamber TPC in a clean room.

Photo: XENON1T / Purdue University

A team of physicists at the University of Cambridge suspects that dark energy may have muddled results from the XENON1T experiment, a series of underground vats of xenon that are being used to search for dark matter.


Dark matter and dark energy are two of the most discussed quandaries of contemporary physics. The two darks are placeholder names for mysterious somethings that seem to be affecting the behavior of the universe and the stuff in it. Dark matter refers to the seemingly invisible mass that only makes itself known through its gravitational effects. Dark energy refers to the as-yet unexplained reason for the universe’s accelerating expansion. Dark matter is thought to make up about 27% of the universe, while dark energy is 68%, according to NASA.

Physicists have some ideas to explain dark matter: axions, WIMPs, SIMPs, and primordial black holes, to name a few. But dark energy is a lot more enigmatic, and now a group of researchers working on XENON1T data says an unexpected excess of activity could be due to that unknown force, rather than any dark matter candidate. The team’s research was published this week in Physical Review D.

The XENON1T experiment, buried below Italy’s Apennine Mountains, is set up to be as far away from any noise as possible. It consists of vats of liquid xenon that will light up if interacted with by a passing particle. As previously reported by Gizmodo, in June 2020 the XENON1T team reported that the project was seeing more interactions than it ought to be under the Standard Model of physics, meaning that it could be detecting theorized subatomic particles like axions—or something could be screwy with the experiment.

“These sorts of excesses are often flukes, but once in a while they can also lead to fundamental discoveries,” said Luca Visinelli, a researcher at Frascati National Laboratories in Italy and a co-author of the study, in a University of Cambridge release. “We explored a model in which this signal could be attributable to dark energy, rather than the dark matter the experiment was originally devised to detect.”

“We first need to know that this wasn’t simply a fluke,” Visinelli added. “If XENON1T actually saw something, you’d expect to see a similar excess again in future experiments, but this time with a much stronger signal.”


Despite constituting so much of the universe, dark energy has not yet been identified. Many models suggest that there may be some fifth force besides the known four known fundamental forces in the universe, one that is hidden until you get to some of the largest-scale phenomena, like the universe’s ever-faster expansion.

Axions shooting out of the Sun seemed a possible explanation for the excess signal, but there were holes in that idea, as it would require a re-think of what we know about stars. “Even our Sun would not agree with the best theoretical models and experiments as well as it does now,” one researcher told Gizmodo last year.

Part of the problem with looking for dark energy are “chameleon particles” (also known as solar axions or solar chameleons), so-called for their theorized ability to vary in mass based on the amount of matter around them. That would make the particles’ mass larger when passing through a dense object like Earth and would make their force on surrounding masses smaller, as New Atlas explained in 2019. The recent research team built a model that uses chameleon screening to probe how dark energy behaves on scales well beyond that of the dense local universe.

“Our chameleon screening shuts down the production of dark energy particles in very dense objects, avoiding the problems faced by solar axions,” said lead author Sunny Vagnozzi, a cosmologist at Cambridge’s Kavli Institute for Cosmology, in a university release. “It also allows us to decouple what happens in the local very dense Universe from what happens on the largest scales, where the density is extremely low.”

The model allowed the team to understand how XENON1T would behave if the dark energy were produced in a magnetically strong region of the Sun. Their calculations indicated that dark energy could be detected with XENON1T.

Since the excess was first discovered, ​​the XENON1T team “tried in any way to destroy it,” as one researcher told The New York Times. The signal’s obstinacy is as perplexing as it is thrilling.

“The authors propose an exciting and interesting possibility to expand the scope of the dark matter detection experiments towards the direct detection of dark energy,” Zara Bagdasarian, a physicist at UC Berkeley who was unaffiliated with the recent paper, told Gizmodo in an email. “The case study of XENON1T excess is definitely not conclusive, and we have to wait for more data from more experiments to test the validity of the solar chameleons idea.”

The next generation of XENON1T, called XENONnT, is slated to have its first experimental runs later this year. Upgrades to the experiment will hopefully seal out any noise and help physicists home in on what exactly is messing with the subterranean detector.

  

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Mysterious new dark energy could be driving expansion of the universe: Study

Albert Einstein was the first person to theorise that space is not empty and that it is possible for more space to come into existence.

India Today Web Desk New DelhiSeptember 22, 2021


The Atacama Cosmology Telescope in Chile. (File Photo)

One of the biggest questions surrounding cosmology and astronomy is how the universe began. We know a lot about the evolution of the planet and the human species, however, the understanding of the origins of the universe and what drives this massive force, remains little. Cosmologists have now stumbled upon a unique phenomenon, which could be driving the expansion of the universe.

Cosmologists speculate that this unique energy may have existed just after the Big Bang happened, barely 3,00,000 years after the explosion. In a series of studies published in preprint, researchers identify it as Early Dark Energy which has been detected in data from the Atacama Cosmology Telescope in Chile.

This data was collected between 2013 and 2016, and if confirmed, it could shed light on the early universe. However, researchers also maintain that it's not definitive proof and more research is required in the area. Researchers believe that this early dark energy was not as strong as today's to accelerate the expansion and would have caused the plasma that emerged from the Big Bang to cool down faster.

Cosmologists speculate that interpreting the observations from the telescope on the basis of this early dark energy may put the universe to be 12.4 billion years old, which is 11 per cent younger than 13.8 billion years calculated by initial observations.


Early dark energy was not as strong as today's to accelerate the expansion. (Representative Photo)

“If this really is true — if the early Universe really did feature early dark energy — then we should see a strong signal," Colin Hill, a co-author of the ACT paper, told Nature. He added that the current expansion would be about 5 per cent faster than the standard model predicts — closer to what astronomers calculate today.

What is Dark Energy?

It was initially believed that the Universe was expanding. However, astronomers thought that gravity was certain to slow the expansion. But observations from the Hubble Space Telescope showed that the expansion was not slowing due to gravity and instead has been accelerating, researchers knew a mysterious force was driving this expansion, which later came to be known as Dark Energy.

Albert Einstein was the first person to theorise that space is not empty and that it is possible for more space to come into existence and his gravity theory proposed that space can possess its own energy. "Because this energy is a property of space itself, it would not be diluted as space expands. As more space comes into existence, more of this energy-of-space would appear."

According to Nasa, we know how much dark energy there is because we know how it affects the universe's expansion. "Other than that, it is a complete mystery," the agency said, adding that roughly 68 per cent of the universe is dark energy. Dark matter makes up about 27 per cent. The rest — everything on Earth, everything ever observed with all of our instruments, all normal matter — adds up to less than 5 per cent of the universe.

IT'S ETHER

Dark energy might be neither particle nor field

Everything else in the universe is either a particle or field. Dark energy behaves as neither, and it may be a property inherent to space itself.

There is a large suite of scientific evidence that supports the picture of the expanding Universe and the Big Bang, complete with dark energy. The late-time accelerated expansion doesn’t strictly conserve energy, but the presence of a new component to the Universe, known as dark energy, is required to explain what we observe

. (Credit: NASA / GSFC)

KEY TAKEAWAYS


Dark energy dominates the energy content of the universe, making up more than 2/3rds of all that's out there.


But while everything else clumps or clusters together, dark energy remains uniform throughout space and time.


Instead of being a particle or field, it could be a property inherent to space itself, with alternatives creating more problems than they solve.

What is it, at a fundamental level, that makes up the universe? When we ask this question, we typically think about starting with things that we directly observe — things like stars, planets, humans, gas, dust, plasma, and other forms of the matter we know — and dividing them up until you reach something that is indivisible. Although we originally thought that atoms would be these “uncuttable” things, we soon discovered they could be further divided: into electrons and atomic nuclei, which themselves are composed of quarks and gluons.

As we mastered the laws of physics and began to manipulate these subatomic particles, we gained the ability to accelerate and collide them, enabling the creation of a wide slew of particles and antiparticles: everything described by the Standard Model of particle physics. And yet, if we add up the sum total of all of these forms of matter, including photons, neutrinos, and everything that does not compose atoms, we fall far short of what is needed to describe our universe. Two additional components are necessary: dark matter and dark energy. Moreover, although we fully expect there to be a particle responsible for dark matter, that is not the case at all for dark energy. Here’s why.

The particles and antiparticles of the Standard Model obey all sorts of conservation laws, with fundamental differences between fermionic particles and antiparticles and bosonic ones. Each set of particles possesses its own unique quantum numbers, but no particles here can explain dark matter or dark energy. (Credit: E. Siegel / Beyond the Galaxy)

Particles, at least as we know them, all have a few things in common. They have a set of “quantum numbers,” or properties that are inherent to them that determine their masses, spins, and various charges. All particles of the same type — electrons, down quarks, Z-bosons, etc. — have identical properties to one another, and you could replace any one of them with any other identical particle and everything would remain the same. The only things that differ between them are either random, like their decay lifetime (if they are unstable), or situational: things like their momentum, orbital angular momentum, or energy levels within a bound system.

But there is another way to break these various particles up: into massive and massless categories. Massive particles slow down as the universe expands and cools during the hot Big Bang and eventually gravitationally clump together, as every mass universally attracts every other mass. Massless particles, however, simply travel through curved space at the only permissible speed, the speed of light, until they interact with another particle in their path. Massive (matter) and massless (radiation) particles evolve in fundamentally different ways with respect to the expanding universe.

While matter and radiation become less dense as the universe expands owing to its increasing volume, dark energy is a form of energy inherent to space itself. As new space gets created in the expanding universe, the dark energy density remains constant. (Credit: E. Siegel / Beyond the Galaxy)

Astrophysically, when we survey the universe in all the different ways we know of, it reveals a variety of aspects of the cosmic story. By observing how abundant the lightest elements and their isotopes are, we can determine how much normal matter, total, makes up our universe. By measuring how galaxies clump and cluster together, as well as their large-scale distribution and individual, internal properties, we can determine how much total “stuff” there is that behaves as though it is made of massive particles. And when we look at the details embedded in the leftover glow from the Big Bang — the cosmic microwave background — it tells us that the universe is spatially flat, telling us how much total “stuff” is present in the universe, overall.

From this information, we learn that all of the normal, Standard Model material in our universe comes out to just 5 percent of the total. Another ~27 percent is dark matter, which cannot behave like any of the known particles. It clumps and gravitates like normal matter but appears to have zero cross-section — i.e., doesn’t collide — with normal matter, light, or other dark matter particles. Although we can only detect dark matter’s presence through its gravitational influence, it is immediately apparent that dark matter is distributed far more diffusely than normal matter; it isn’t as clumpy, particularly on small cosmic scales. Unfortunately, all attempts at direct detection experiments have failed to yield a robust, positive signal. Its true nature remains mysterious.

Light may be emitted at a particular wavelength, but the expansion of the universe will stretch it as it travels. Light emitted in the ultraviolet will be shifted all the way into the infrared when considering a galaxy whose light arrives from 13.4 billion years ago. The more the expansion of the universe accelerates, the greater the light from distant objects will be redshifted and the fainter it will appear. 

(Credit: Larry McNish / RASC Calgary)

Even with normal matter and dark matter combined, though, we haven’t gotten close to finding everything. The remaining ~68 percent of the universe is unaccounted for, and our big clue toward what that “stuff” is first came in the 1990s, when observations of distant supernovae appeared fainter than our models of the universe were predicting. It was as though something else beyond what we expected — various forms of matter and radiation — was contributing to the universe. As the evidence poured in, bolstered by the cosmic microwave background and large-scale clustering data, we realized that a wholly novel form of energy, inconsistent with the properties of any form of matter or radiation, must be present: what we call dark energy today.

What is remarkable about the evidence for dark energy is how perfectly uniform it is. There is no evidence that there’s more or less dark energy in the space occupied by rich galaxy clusters than in the voids of empty space. There is no evidence that dark energy correlates with density, direction, location, or epoch of the universe. It appears to be perfectly uniform, perfectly homogeneous, and perfectly constant: unchanging throughout space and time. And yet, despite its simplicity, it behaves fundamentally differently from all other known forms of energy.

Various components of and contributors to the universe’s energy density, and when they might dominate. Note that radiation is dominant over matter for roughly the first 9,000 years, then matter dominates, and finally, a cosmological constant emerges. (The others do not exist in appreciable amounts.) However, dark energy may not be a cosmological constant, exactly. (Credit: E. Siegel / Beyond the Galaxy)

Every form of matter and radiation in the universe is linked to quantum particles in some way. Normal matter is made up of subatomic particles: particles of which there are a finite number. As the universe expands, the number of particles stays the same while the volume increases, hence matter gets less dense as time marches forward. Similarly, radiation is quantized into particles as well (even, theoretically, gravitational radiation, which should be quantized into gravitons), but these particles are massless. As the universe expands, not only does the number of particles remain the same while the volume increases, but the energy of each individual particle decreases as the universe expands.

Still, both of these descriptions fall apart for dark energy. As the volume of the universe increases — as it expands — the energy density does not change; it remains constant. It’s as though there is something present through all of space that isn’t dependent on anything else: matter density, radiation density, temperature, changes in volume, etc. Although we can measure and quantify its effects on the universe, we cannot say that we understand dark energy’s nature. It could be a

particle of some type,

a field that permeates the universe,

or even a property inherent to the fabric of space itself.

A universe with dark energy (red), a universe with large inhomogeneity energy (blue), and a critical, dark energy-free universe (green). Note that the blue line behaves differently from dark energy. New ideas should make different, observably testable predictions from the other leading ideas. And ideas which have failed those observational tests should be abandoned once they reach the point of absurdity. 

(Credit: Gabor Racz et al., 2017)

Of course, each of these scenarios leads to a vastly different conception of the universe and what is present within it. If dark energy is a particle, then either new particles must constantly be created to keep the energy density constant, or the behavior of these particles must evolve with time to keep their effects on the universe constant. If dark energy is a field that permeates the universe, then it is permitted to evolve in either space or time or both, and any observed evidence (we have none) of such a variation would point in this direction; models of quintessence fall into this category.

But if we follow the observations, there is no evidence that dark energy is anything other than the most basic entity imaginable: a property that is uniformly inherent to space everywhere and at all times. This can come about in one of two different ways very easily:
The universe can possess a positive, non-zero cosmological constant, a term perfectly allowable in general relativity. It has to be very, very small, but when you put it in everywhere over the whole universe, it eventually comes to dominate.
It could be a quantum property of space: the zero-point energy of all the fields in the vacuum of space is not required to be zero but could take on some positive, non-zero value. What we often interpret as quantum fluctuations, or particle-antiparticle pairs popping in and out of existence, could be the cause behind dark energy.

Visualization of a quantum field theory calculation showing virtual particles in the quantum vacuum (specifically, for the strong interactions). Even in empty space, this vacuum energy is non-zero. (Credit: Derek Leinweber)

From a theoretical perspective, it is important to keep in mind that until we understand the nature of dark energy, which is to say that we acquire some sort of evidence that points toward one possibility over another, we have to keep all of these options in mind. Dark energy could be linked to the inflationary epoch that set up and gave rise to the Big Bang; dark energy could have been important and impactful early on in the universe’s history before decaying to its present, low-density state; dark energy could be slowly evolving or inhomogeneous, or could have a slightly higher or lower density dependent on what else is around. Theoretically, all options remain on the table.

But that is also why we don’t simply base our conclusions on theory alone. The whole idea of science is based on the notion that the way we find out information about the universe is by putting the universe itself to the test: through measurement, experiment, and observation. As we study:

the cosmic microwave background down to smaller and smaller scales, in more wavelength bands and with polarization included;

the large-scale structure of the universe out to greater distances, fainter objects, and larger areas on the sky;

and individually luminous objects, out to greater precision and greater distances,

we gain the ability to see whether there is any indication that dark energy is anything other than a pure constant, and whether it shows evidence for any evolution or inhomogeneities in time and/or space.

This snippet from a structure-formation simulation, with the expansion of the universe scaled out, represents billions of years of gravitational growth in a dark matter-rich universe. Even though the universe is expanding, the individual, bound objects within it no longer expand. Their sizes, however, may be impacted by the expansion; we do not know for certain. 

(Credit: Ralf Kahler and Tom Abel (KIPAC) / Oliver Hahn)

Of course, it hasn’t. Fifteen years ago, we were able to constrain that dark energy was a constant to a precision of ±30 percent or so. Today, that has improved to a precision of ±7 percent or so, with the next generation of space-based and ground-based observatories — particularly ESA’s Euclid, NSF’s Vera Rubin observatory, and NASA’s Nancy Roman telescope — poised to take us to a precision of just ±1 percent. If there are any imperfections, inhomogeneities, or evolutionary effects that occur in the dark energy sector, these upcoming surveys will be our best bet at uncovering them.

However, there are other methods that could reveal some more exotic interpretations. Recently, the XENON experiment claimed to see an excess of events over the anticipated background, beyond what conventional sources could explain. There are three main interpretations on the table, at present:

the result is an experimental fluke that will go away with better statistics, which is within the realm of possibility;

that this is our first evidence of an unexpected type of dark matter, whose explanations would require additional contortions over what was theorized previously; 

or

a new source of background that hasn’t been included in the analysis (such as tritium in the water) is causing it.

Of these explanations, most physicists favor the last one. But, as we said earlier, all possibilities, no matter how exotic or strange, have to be kept in mind.

The XENON1T detector, with its low-background cryostat, is installed in the centre of a large water shield to protect the instrument against cosmic ray backgrounds. This setup enables the scientists working on the XENON1T experiment to greatly reduce their background noise and more confidently discover the signals from processes that they are attempting to study. XENON is not only searching for heavy, WIMP-like dark matter but other forms of potential dark matter and dark energy. 

(Credit: XENON1T Collaboration)

That is where, as was recently shown by a small team of scientists, the idea of chameleon dark energy comes into play. If dark energy is actually a very specific, exotic type of particle that has its clumping and density restricted in the most matter-rich regions of space, it could have potentially created the signal seen by the XENON experiment. With some additional theoretical contortions, the team was able to conclude, at the ~95 percent confidence level, that this interpretation is favored over the null hypothesis: that the result is a mere fluke.

Of course, what most people do not realize is that this is precisely what most ideas in theoretical physics look like: you add in one or two new free parameters to explain one or two new phenomena. Most ideas like this are not new, but rather are variations on an old idea, and most ideas in this vein are colossally bad: they are ill-motivated and are considered only because experiments are nearing the precision necessary to rule them out, either wholly or at least in part. In physics, as well, a signal at ~95 percent confidence is barely worth a second look; this idea of chameleon dark energy particles likely will never rear its head again in any experimental setting.

Constraints on the total matter content (normal + dark, x-axis) and dark energy density (y-axis) from three independent sources: supernovae, the CMB (cosmic microwave background), and BAO (which is a wiggly feature seen in the correlations of large-scale structure). Note that even without supernovae, we would need dark energy for certain, and also that there are uncertainties and degeneracies between the amount of dark matter and dark energy that we would need to accurately describe our universe. 

(Credit: Supernova Cosmology Project, Amanullah et al., ApJ, 2010.)

When you take away wishful thinking and look only at the evidence that we have, the story the universe tells is very simple, albeit counterintuitive. The stuff that we thoroughly understand — the matter and radiation composed of all the known particles of the Standard Model plus gravitational waves — makes up only 5 percent of the total of what’s out there. There is another form of mass, dark matter, that makes up an additional ~27 percent or so. But the majority of what is present, the ~68 percent of the universe that is dark energy, doesn’t appear to either be a particle or change with time. It behaves neither as a particle nor as a field, but rather as a property that is inherent to space itself.

Although it is a fun exercise to consider what might happen under a variety of exotic conditions, particularly when experiments or observations are reaching the sensitivities necessary to probe them, it is vital to treat them as the fringe hypotheses that they are. The default, working hypothesis of what dark energy is doesn’t include extra couplings, clumpiness, time-or-space evolution, or anything else beyond a simple constant in space. It is time to take seriously the idea that dark energy might simply be a property inherent to the very fabric of space. Until we learn how to calculate the zero-point energy of empty space itself, or gain some bizarre, surprising, and unanticipated evidence, this will remain one of the biggest existential questions in all the universe.

Ethan Siegel
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Dark energy from supermassive black holes? Physicists spar over radical idea

New theory aims to account for one of the universe’s great mysteries

17 FEB 2023
BY ADAM MANN

An artist's impression of a supermassive black hole in the center of a galaxy. New reseach links these behemoths to the mysterious phenomenon called dark energy.NASA/JPL-CALTECH

Earlier this week, a study made headlines claiming that the mysterious “dark energy” cosmologists believe is accelerating the expansion of the universe could arise from supermassive black holes at the hearts of galaxies. If true, the connection would link two of the most mind-bending concepts in physics—black holes and dark energy—and suggest that the source of the latter has been under theorists’ noses for decades. However, some leading theorists are deeply skeptical of the idea.

“What they are proposing makes no sense to me,” says Robert Wald, a theoretical physicist at the University of Chicago who specializes in Albert Einstein’s general theory of relativity, the standard understanding of gravity. Other theorists were more receptive to the radical claim—even if it ends up being wrong. “I’m personally excited about it,” says astrophysicist Niayesh Afshordi of the Perimeter Institute for Theoretical Physics.

At first blush, black holes and dark energy seem to have nothing to do with each other. According to general relativity, a black hole is a pure gravitational field so strong that its own energy sustains its existence. Such peculiar beasts are thought to emerge when massive stars collapse to an infinitesimal point, leaving just their gravitational fields behind. Supermassive black holes having millions or billions of times the mass of our Sun are believed to lurk in the hearts of galaxies.

In contrast, dark energy is a mysterious phenomenon that literally stretches space and is accelerating the expansion of the universe. Theorists think dark energy could represent some new sort of field in space, a bit like an electric field, or it could be a fundamental property of empty space itself.

So how could the two be connected? Quantum mechanics suggests that the vacuum of empty space should contain a type of energy known as vacuum energy. This is thought to be spread throughout the universe and exert a force opposing gravity, making it a prime candidate for the identity of dark energy. In 1966, Soviet physicist Erast Gliner showed that Einstein’s equations could also produce objects that to outside observers look and behave exactly like a black hole—yet are, in fact, giant balls of vacuum energy.

If such objects were to exist, it would mean that rather than being uniformly spread throughout space, dark energy is actually confined to specific locations: the interiors of black holes. Even bound in these particular knots, dark energy would still exert its space-stretching effect on the universe.

One consequence of this idea—that supermassive black holes are the source of dark energy—is that they would be linked to the constant stretching of space and their mass should change as the universe expands, says astrophysicist Duncan Farrah of the University of Hawaii, Manoa. “If the volume of the universe doubles, so does the mass of the black hole,” he adds.

To test this possibility, Farrah and his colleagues studied elliptical galaxies, which contain black holes with millions or billions of times the Sun’s mass in their centers. They focused on galaxies with little gas or dust floating around between their stars, which would provide a reservoir of material that the central black hole could feed on. Such black holes wouldn’t be expected to change much over the course of cosmic history.

Yet by analyzing the properties of ellipticals over roughly 9 billion years, the team saw that black holes in the early universe were much smaller relative to their host galaxy than those in the modern universe, indicating they had grown by a factor of seven to 10 times in mass, Farrah and colleagues reported this month in the Astrophysical Journal.

The fact that the black holes swelled while the galaxies didn’t is the key, Farrah says. If the black holes had grown by feeding on nearby gas and dust, that material should have also generated many new stars in parts of the galaxy far from the black hole. But if black holes were made from dark energy, they would react to changes in the universe’s size in exactly the way that researchers observed in the centers of elliptical galaxies, Farrah’s team additionally reported this week in Astrophysical Journal Letters.

Wald is unpersuaded. He questions how an orb of pure dark energy could be stable. He also says the numbers don’t seem to add up: Dark energy is known to make up 70% of the mass-energy of the universe, whereas black holes are a mere fraction of the ordinary matter, which constitutes less than 5% of the universe. “I don't see how it is in any way conceivable that such objects could be relevant to the observed dark energy,” he says.

Others are taking a wait-and-see attitude. “At the moment, this is an interesting possibility,” says cosmologist Geraint Lewis of the University of Sydney, but “there would have to be a lot more evidence on the table if this is even a remotely plausible source of dark energy.”

Afshordi agrees. If black holes and dark energy are linked in this way, it would likely have other visible consequences in the universe, he says. At the moment, though, he’s unsure what those would be. Determining exactly how galaxies evolve over time is a tricky business, he adds, and there could be other mechanisms to grow black holes that the team hasn’t considered.

Nevertheless, Afshordi is supportive of efforts to rethink fundamental assumptions about the universe. “Most new theoretical ideas are dismissed by skepticism,” he says. “But if we dismiss all the new ideas then there won’t be anything left.”

SEE 

https://plawiuk.blogspot.com/2023/02/1st-observational-evidence-linking.html

LA REVUE GAUCHE - Left Comment: Search results for DARK MATTER 

LA REVUE GAUCHE - Left Comment: Search results for DARK ENERGY 

LA REVUE GAUCHE - Left Comment: Search results for ETHER 

A new study of exploding stars shows dark energy may be more complicated than we thought

The Conversation
January 12, 2024 

The remains of a Type Ia supernova – a kind of exploding star used to measure distances in the universe. NASA / CXC / U.Texas, CC BY

What is the universe made of? This question has driven astronomers for hundreds of years.

For the past quarter of a century, scientists have believed “normal” stuff like atoms and molecules that make up you, me, Earth, and nearly everything we can see only accounts for 5% of the universe. Another 25% is “dark matter”, an unknown substance we can’t see but which we can detect through how it affects normal matter via gravity.

The remaining 70% of the cosmos is made of “dark energy”. Discovered in 1998, this is an unknown form of energy believed to be making the universe expand at an ever-increasing rate.

In a new study soon to be published in the Astronomical Journal, we have measured the properties of dark energy in more detail than ever before. Our results show it may be a hypothetical vacuum energy first proposed by Einstein – or it may be something stranger and more complicated that changes over time.

What is dark energy?

When Einstein developed the General Theory of Relativity over a century ago, he realised his equations showed the universe should either be expanding or shrinking. This seemed wrong to him, so he added a “cosmological constant” – a kind of energy inherent in empty space – to balance out the force of gravity and keep the universe static.

Later, when the work of Henrietta Swan Leavitt and Edwin Hubble showed the universe was indeed expanding, Einstein did away with the cosmological constant, calling it his “greatest mistake”.

However, in 1998, two teams of researchers found the expansion of the universe was actually accelerating. This implies that something quite similar to Einstein’s cosmological constant may exist after all – something we now call dark energy.

Since those initial measurements, we’ve been using supernovae and other probes to measure the nature of dark energy. Until now, these results have shown the density of dark energy in the universe appears to be constant.


This means the strength of dark energy remains the same, even as the universe grows – it doesn’t seem to be spread more thinly as the universe gets bigger. We measure this with a number called w. Einstein’s cosmological constant in effect set w to –1, and earlier observations have suggested this was about right.
Exploding stars as cosmic measuring sticks

How do we measure what is in the universe and how fast it is growing? We don’t have enormous tape measures or giant scales, so instead we use “standard candles”: objects in space whose brightness we know.

Imagine it is night and you are standing on a long road with a few light poles. These poles all have the same light bulb, but the poles further away are fainter than the nearby ones.



In a Type Ia supernova, a white dwarf slowly pulls mass from a neighboring star before exploding. NASA / JPL-Caltech, CC BY


This is because light fades proportionately to distance. If we know the power of the bulb, and can measure how bright the bulb appears to be, we can calculate the distance to the light pole.

For astronomers, a common cosmic light bulb is a kind of exploding star called a Type Ia supernova. These are white dwarf stars which often suck in matter from a neighbouring star and grow until they reach 1.44 times the mass of our Sun, at which point they explode. By measuring how quickly the explosion fades, we can determine how bright it was and hence how far away from us.

The Dark Energy Survey

The Dark Energy Survey is the largest effort yet to measure dark energy. More than 400 scientists across multiple continents work together for nearly a decade to repeatedly observe parts of the southern sky.

Repeated observations let us look for changes, like new exploding stars. The more often you observe, the better you can measure these changes, and the larger the area you search, the more supernovae you can find.


The Cerro Tololo Inter-American Observatory 4-metre telescope which was used by and the Dark Energy Survey. Reidar Hahn / Fermilab, CC BY

The first results indicating the existence of dark energy used only a couple of dozen supernovae. The latest results from the Dark Energy Survey use around 1,500 exploding stars, giving much greater precision.

Using a specially built camera installed on the 4-metre Blanco Telescope at the Cerro-Tololo Inter-American Observatory in Chile, the survey found thousands of supernovae of different types. To work out which ones were Type Ia (the kind we need for measuring distances), we used the 4-metre Anglo Australian Telescope at Siding Spring Observatory in New South Wales.

The Anglo Australian Telescope took measurements which broke up the colours of light from the supernovae. This lets us see a “fingerprint” of the individual elements in the explosion.

Type Ia supernovae have some unique features, like containing no hydrogen and silicon. And with enough supernovae, machine learning allowed us to classify thousands of supernovae efficiently.

More complicated than the cosmological constant

Finally, after more than a decade of work and studying around 1,500 Type Ia supernovae, the Dark Energy Survey has produced a new best measurement of w. We found w = –0.80 ± 0.18, so it’s somewhere between –0.62 and –0.98.

This is a very interesting result. It is close to –1, but not quite exactly there. To be the cosmological constant, or the energy of empty space, it would need to be exactly –1.

Where does this leave us? With the idea that a more complex model of dark energy may be needed, perhaps one in which this mysterious energy has changed over the life of the universe.

Brad E Tucker, Astrophysicist/Cosmologist, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Dark energy is forcing the universe to expand. This new observatory may show us how

Monisha Ravisetti
Thu, February 1, 2024

The silhouette of an observatory sits atop a dark hill beneath the milky way stretched across a starry sky.


As our universe poofs out in every direction like an indestructible balloon — thanks to dark energy, a force fully hidden to the human eye — Dillon Brout is an astrophysicist trying to make sense of it all.

Brout wishes to unveil the strange correlation that exists between the invisible and visible universe, understand how the fabric of spacetime flows and perhaps finally reveal the truth about whatever's causing the cosmos to bubble outward faster and faster by the day.

To do this, he collects supernovas.


When picking out which supernovas to add to the shelf, however, Brout isn't interested in them all. These star explosions are typically divided into two main categories: Type 2 and Type 1a. Brout wants the Type 1a's, and his reasoning is actually pretty simple:

"They're not all exactly the same, but they're very similar," he told Space.com.

Related: How fast is the universe expanding? New supernova data could help nail it down

In essence, to solve all those aforementioned space mysteries, you need to measure some distances on cosmological scales. Only then can you know, for instance, how far and how quickly dark energy seems to have forced space to expand. Reverse calculate from there, and maybe you learn something about the nature of dark energy itself, too. Yet, to measure even such grand distances and elusive concepts, to probe how far back we can see and how much farther back that point is traveling, you still need something as basic as a ruler.

Fortunately, because they're so standardized in brightness and general behavior, Type 1a supernovas are like the ticks on light-years-long rulers plunging through space. In fact, astronomers like to call them "standard candles" for this reason. They're perfect lighthouses that guide us as we calibrate our equations and search for some answers. The more we have, the better.

a yellow gaseous star is being stretched and eaten by a bigger, blue star, which quickly engulfs the yellow and enlarges by several scales.

Looking for efficiency and accuracy, Brout fills up his supernova collection by employing machine learning algorithms that vigorously scout out as many Type 1a's as possible. (Yet another reason why Type 1a standardization is helpful. Consistent algorithms love consistency.)

He's part of the Dark Energy Survey collaboration, and earlier this month, the team announced their algorithms managed to detect 1,500 of these luminous natural markers — in only five years. That's a pretty big deal. For context, Brout says it took scientists 30 years of regular Type 1a searching (aka, through using a trusty spectrograph) to find the previous 1,500 total subjects. DES got the same result within about a sixth of that timeframe.

"One of the main things that made DES so special is that it covered so much area on the sky," Brout said, adding that he trusts his algorithms enough to say cross-checking the same parameters is more or less not needed.

But things are about to heavily ramp up.

Though DES yielded an impressive amount of Type 1a's, its associated instrument, the Dark Energy Camera, only covered 30 square degrees of sky. That's a relatively small fraction, Brout says. Enter: The Rubin Observatory.

Or, more specifically, the Legacy Survey of Space and Time that'll be created in part by using the state-of-the-art LSST Camera starting next year.

two dimly lit observatories sit as stunted domes beneath a vibrant night sky and a stretch of blue hued milky way.

"LSST is going to observe the entire observable southern night sky," Brout said. "You're going to go from DES discovering 1,500 to LSST discovering a million alerts, and we're going to filter that down, hopefully, using machine learning and other algorithms to get a few 100,000 Type 1a supernovas."

One specific question waiting to be answered

Fortunately once more, the Rubin Observatory is officially on track to be totally built later this year and the LSST will begin its journey early-to-mid next from the top of a Chilean summit, Victor Krabbendam, the observatory's construction project manager said during the 243rd meeting of the American Astronomical Society in January 2024. "We're about 10 years into the actual construction phase," he said. "The sun is setting and we're getting close."

And actually, Brout already has a specific puzzle waiting to be solved with the LSST.

With their major 1,500 Type 1a supernova haul announced this month, Brout and fellow researchers sort of confirmed what we presently know about what's called "the cosmological constant," which you can think of as the value that represents dark energy in the universe's expansion equations. It accounts for the acceleration bit that normal physics can't totally explain. This "confirmation" might sound disappointing at first, but in a way, it's quite good progress. It means that one of the most precise calculations of the universe's expansion is telling us that we're probably right about everything we know concerning dark energy so far.

Maybe more interesting, however, is that the team's work sort of hinted at a weird pattern, too. "We do have a section in the paper that combines all of the available probes of dark energy, not just supernova, and what we see is a lot of them are pointing towards a slightly larger value of the 'equation of state' of dark energy, which would imply that it's not a cosmological constant."

In other words, that'd mean there isn't a value to blanket represent dark energy. Maybe it's flexible.

"One of the major benefits we get from this new LSST analysis is that we get a lot more supernovas in the nearby universe, and that's because we're covering so much area of the sky," Brout said. "If you think about it, the nearby universe is the universe that, because of the speed of light, we're seeing the galaxies much closer to as they are today. If you're looking at the faraway universe you're seeing the universe when it was much younger."

That's important, he explains, because the effect of dark energy is believed to be strongest in the recent universe. Why? Here's where it gets really weird.

"Dark energy, we think, is a property of space itself," Brout said. "That's kind of what the cosmological constant embodies, which is like the energy of empty space."

Thus, if dark energy is a property of empty space, that'd mean there's more dark energy in the universe today than there was in the past. This is because the universe is expanding, thereby creating more "space."

"We think it does not dilute as the universe expands," Brout said, "so that means, relative to the amount of matter in the universe and dark matter in the universe, you're getting more and more dark energy."

At this point, like I was, you might be wondering: I'm sorry, what? I thought the universe is contained? Where is the new dark energy coming from? It can't just pop into existence, right?

"That's the million dollar question," Brout said. "Is it just a property of space? Is this a fundamental property of the universe? That as space itself expands, you would just naturally get more dark energy along with it?"

And to get to the bottom of this, we'll soon have a multi-million dollar camera waiting.
2025's golden observatory

There are four major steps left before Brout can start counting the days leading up to LSST's first light. First, the Rubin team must get some key mirrors ready to go. Then, the crew must get the glass necessary for the Simonyi Telescope — which reportedly has flown through tests without even the proper glass component — and mount the commissioning camera thereafter. Finally, the approximately $200 million LSST camera, currently being put together on the West Coast, will earn its spot.

a tiny person in a full white jumpsuit peers into a giant lens attached to metal supports in a white, dimly lit room.

"You still have to get that from California to the summit. It's a very delicate instrument. It's special in the sense that it's a $200 million camera — irreplaceable," Krabbendam told Space.com.

"It is a massive camera," he said. "It's 3.2 gigapixels for a focal plane."

Related Stories:

— The mysteries of the dark universe could be solved by the Rubin Observatory

— We still don't know what dark matter is, but here's what it's not

— Hypothetical 'dark photons' could shed light on mysterious dark matter

One gigapixel, for context, is equal to one billion pixels; a standard DSLR camera works on scales of megapixels, or millions of pixels. To really drive this home, consider how a million seconds is 12 days; a billion seconds is 31 years. So… picture that resolution of camera power scanning the entire observable southern sky.

This is why the observatory, built with about $500 million of National Science Foundation funding and a few $100 million of Department of Energy funding — the latter of which is particularly interested in dark energy studies like Brout's — is so highly anticipated.

So highly anticipated.

Update 2/1: 1 million seconds is equal to 12 days, this article has been updated to reflect that.

 

Supernovae twins open up new possibilities for precision cosmology

Findings will enhance dark energy experiments at major telescopes

DOE/LAWRENCE BERKELEY NATIONAL LABORATORY

Research News

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IMAGE: THE UPPER LEFT FIGURE SHOWS THE SPECTRA -- BRIGHTNESS VERSUS WAVELENGTH -- FOR TWO SUPERNOVAE. ONE IS NEARBY AND ONE IS VERY DISTANT. TO MEASURE DARK ENERGY, SCIENTISTS NEED TO... view more 

CREDIT: GRAPHIC CREDIT: ZOSIA ROSTOMIAN/BERKELEY LAB; PHOTO CREDIT: NASA/ESA)

Cosmologists have found a way to double the accuracy of measuring distances to supernova explosions - one of their tried-and-true tools for studying the mysterious dark energy that is making the universe expand faster and faster. The results from the Nearby Supernova Factory (SNfactory) collaboration, led by Greg Aldering of the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), will enable scientists to study dark energy with greatly improved precision and accuracy, and provide a powerful crosscheck of the technique across vast distances and time. The findings will also be central to major upcoming cosmology experiments that will use new ground and space telescopes to test alternative explanations of dark energy.

Two papers published in The Astrophysical Journal report these findings, with Kyle Boone as lead author. Currently a postdoctoral fellow at the University of Washington, Boone is a former graduate student of Nobel Laureate Saul Perlmutter, the Berkeley Lab senior scientist and UC Berkeley professor who led one of the teams that originally discovered dark energy. Perlmutter was also a co-author on both studies.

Supernovae were used in 1998 to make the startling discovery that the expansion of the universe is speeding up, rather than slowing down as had been expected. This acceleration - attributed to the dark energy that makes up two-thirds of all the energy in the universe - has since been confirmed by a variety of independent techniques as well as with more detailed studies of supernovae.

The discovery of dark energy relied on using a particular class of supernovae, Type Ia. These supernovae always explode with nearly the same intrinsic maximum brightness. Because the observed maximum brightness of the supernova is used to infer its distance, the small remaining variations in the intrinsic maximum brightness limited the precision with which dark energy could be tested. Despite 20 years of improvements by many groups, supernovae studies of dark energy have until now remained limited by these variations.

Quadrupling the number of supernovae

The new results announced by the SNfactory come from a multi-year study devoted entirely to increasing the precision of cosmological measurements made with supernovae. Measurement of dark energy requires comparisons of the maximum brightnesses of distant supernovae billions of light-years away with those of nearby supernovae "only" 300 million light-years away. The team studied hundreds of such nearby supernovae in exquisite detail. Each supernova was measured a number of times, at intervals of a few days. Each measurement examined the spectrum of the supernova, recording its intensity across the wavelength range of visible light. An instrument custom-made for this investigation, the SuperNova Integral Field Spectrometer, installed at the University of Hawaii 2.2-meter telescope at Maunakea, was used to measure the spectra.

"We've long had this idea that if the physics of the explosion of two supernovae were the same, their maximum brightnesses would be the same. Using the Nearby Supernova Factory spectra as a kind of CAT scan through the supernova explosion, we could test this idea," said Perlmutter.

Indeed, several years ago, physicist Hannah Fakhouri, then a graduate student working with Perlmutter, made a discovery key to today's results. Looking at a multitude of spectra taken by the SNfactory, she found that in quite a number of instances, the spectra from two different supernovae looked very nearly identical. Among the 50 or so supernovae, some were virtually identical twins. When the wiggly spectra of a pair of twins were superimposed, to the eye there was just a single track. The current analysis builds on this observation to model the behavior of supernovae in the period near the time of their maximum brightness.

The new work nearly quadruples the number of supernovae used in the analysis. This made the sample large enough to apply machine-learning techniques to identify these twins, leading to the discovery that Type Ia supernova spectra vary in only three ways. The intrinsic brightnesses of the supernovae also depend primarily on these three observed differences, making it possible to measure supernova distances to the remarkable accuracy of about 3%.

Just as important, this new method does not suffer from the biases that have beset previous methods, seen when comparing supernovae found in different types of galaxies. Since nearby galaxies are somewhat different than distant ones, there was a serious concern that such dependence would produce false readings in the dark energy measurement. Now this concern can be greatly reduced by measuring distant supernovae with this new technique.

In describing this work, Boone noted, "Conventional measurement of supernova distances uses light curves - images taken in several colors as a supernova brightens and fades. Instead, we used a spectrum of each supernova. These are so much more detailed, and with machine-learning techniques it then became possible to discern the complex behavior that was key to measuring more accurate distances."

The results from Boone's papers will benefit two upcoming major experiments. The first experiment will be at the 8.4-meter Rubin Observatory, under construction in Chile, with its Legacy Survey of Space and Time, a joint project of the Department of Energy and the National Science Foundation. The second is NASA's forthcoming Nancy Grace Roman Space Telescope. These telescopes will measure thousands of supernovae to further improve the measurement of dark energy. They will be able to compare their results with measurements made using complementary techniques.

Aldering, also a co-author on the papers, observed that "not only is this distance measurement technique more accurate, it only requires a single spectrum, taken when a supernova is brightest and thus easiest to observe - a game changer!" Having a variety of techniques is particularly valuable in this field where preconceptions have turned out to be wrong and the need for independent verification is high.

###

The SNfactory collaboration includes Berkeley Lab, the Laboratory for Nuclear Physics and High Energy at Sorbonne University, the Center for Astronomical Research of Lyon, the Institute of Physics of the 2 Infinities at the University Claude Bernard, Yale University, Germany's Humboldt University, the Max Planck Institute for Astrophysics, China's Tsinghua University, the Center for Particle Physics of Marseille, and Clermont Auvergne University.

This work was supported by the Department of Energy's Office of Science, NASA's Astrophysics Division, the Gordon and Betty Moore Foundation, the French National Institute of Nuclear and Particle Physics and the National Institute for Earth Sciences and Astronomy of the French National Centre for Scientific Research, the German Research Foundation and German Aerospace Center, the European Research Council, Tsinghua University, and the National Natural Science Foundation of China.

Additional background

In 1998, two competing groups studying supernovae, the Supernova Cosmology Project and the High-z Supernova Search team, both announced they had found evidence that, contrary to expectations, the expansion of the universe was not slowing but becoming faster and faster. Dark energy is the term used to describe the cause of the acceleration. The 2011 Nobel Prize was awarded to leaders of the two teams: Saul Perlmutter of Berkeley Lab and UC Berkeley, leader of the Supernova Cosmology Project, and to Brian Schmidt of the Australian National University and Adam Riess of Johns Hopkins University, from the High-z team.

Additional techniques for measuring dark energy include the DOE-supported Dark Energy Spectroscopic Instrument, led by Berkeley Lab, which will use spectroscopy on 30 million galaxies in a technique called baryon acoustic oscillation. The Rubin Observatory will also use another called weak gravitational lensing.

Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams, Lawrence Berkeley National Laboratory (https://www.lbl.gov/) and its scientists have been recognized with 14 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab's facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy's Office of Science.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

-By Bob Cahn