Category: dark energy

A European Astronomical Observatory is Announcing an “Unprecedented Discovery”

Moments ago, the European Southern Observatory (ESO) announced that they made a revolutionary discovery, one that they will be unveiling to the world on Monday (October 16th). According to the media advisory released today by the ESO, scientists have observed an astronomical phenomenon that has never been witnessed before.

Beyond that, no information is available regarding this most recent announcement.

A Timeline of Future Space Exploration: Part 1 [INFOGRAPHIC]
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The last time that astronomers unveiled a groundbreaking discovery of this nature was when scientists working at LIGO (the Laser Interferometer Gravitational-Wave Observatory) detected gravitational waves. Ultimately, the find ushered us into a new era in astronomy, allowing us to see the universe as never before.

To clarify, before this detection, we were only able to perceive the cosmos through observations of electromagnetic radiation—through gamma rays, x-rays, visible light, and so on. Thanks to the LIGO discovery, we can now observe the very ripples of spacetime itself.

Remarkably, the waves were even powerful enough to break the Internet, bringing down both the LIGO and American Physical Society websites.

Of course, there are a number of mysteries that scientists have yet to explain in relation the origins and evolution of the cosmos. As such, it is difficult to pin down the specific nature of this observation—perhaps scientists finally observed dark energy, the mysterious force that is thought to make up approximately 73 percent of the universe, or perhaps it is a discovery that scientists never before fathomed. Stay tuned.

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Astronomers Have Uncovered Evidence of “Dynamical Dark Energy”

Baffling Matter in the Universe

For several decades now, since Albert Einstein first posited his general theory of relativity, astronomers have come to understand that what we know and experience to be matter in the Universe is only a tiny fraction of what’s really out there. About 25 percent of the Universe is made up of so-called dark matter, while 68 to 75 percent is dark energy. Both sound like an evil villain’s secret plan for galactic conquest, and indeed they’re often used as such in science fiction.

The reality is, dark matter and dark energy are out there — although their mysterious nature has caused some to credit their existence to an illusion. Though both invisible, we actually see their effects in terms of how these interact with gravity. Dark energy is thought to be a mysterious force that accelerates the expansion of the Universe and is, therefore, considered to be a  cosmological constant according to Einstein — a vacuum energy that’s represented by a constant Equation of State (EoS) of -1, for the purposes of the study.

Now, a collaboration of astronomers, including those from the University of Portsmouth’s (UoP) Institute of Cosmology and Gravitation (ICG), have found evidence that suggests that dark matter may have a dynamic nature. “Since its discovery at the end of last century, dark energy has been a riddle wrapped in an enigma,” ICG director Bob Nichol said in a UoP press release. “We are all desperate to gain some greater insight into its characteristics and origin. Such work helps us make progress in solving this 21st Century mystery.”

A Dynamic Energy

According to their study, published in the journal Nature Astronomy, evidence of dark energy’s dynamic nature comes from high-precision measurements of the Baryonic Acoustic Oscillations (BAO) — periodic fluctuations of a matter composed of protons and neutrons —  at multiple cosmic epochs. These measurements were taken in 2016 by a team that included the lead author of the new study, Gong-Bo Zhao from ICG and the National Astronomical Observatories of China. Combined with a new method which Zhao developed, the astronomers found evidence of dynamical dark energy at an undeniable degree of statistical certainty.

In short, instead of a constant vacuum, dark energy may be some form of dynamical field. “We are excited to see that current observations are able to probe the dynamics of dark energy at this level, and we hope that future observations will confirm what we see today,” Zhao said in the press release.

To confirm their findings, the team is depending on future astronomical surveys to be conducted by next-generation instruments. One of these is the Dark Energy Spectroscopic Instrument (DESI) survey, which is slated to begin work on a 3D cosmic map in 2018. Aside from this, powerful instruments like the long-awaited James Webb Space Telescope could also help to make observations that might shed light on the mysteries of dark energy.

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This Dark Energy Discovery Could Rewrite Physics

Dark Energy Survey

Scientists have discovered a mismatch between a map of the early universe and measurements of the universe today. If the disparity remains through future measurements, that difference could rewrite physics.

The recent results, part of the ongoing Dark Energy Survey (DES) of a huge portion of the southern sky, reveal how matter is distributed among 26 million galaxies. They also provide one of the clearest and most powerful images of our universe to date.

The new data is also being compared with images taken in 2013 with the Planck satellite, which show the universe as it once was. The comparison enables scientists to get an “in motion” sense of the universe as an evolving system, and to make predictions about the future. And while many astronomers think that dark energy is a constant force, these preliminary results seem to suggest that it might not be.

The Planck images showed that dark matter comprised 34 percent of the universe in its early days, but these new findings indicate that it currently makes up only 26 percent.

Understanding how matter is distributed helps us to know how dark energy and dark matter oppose each other in our universe. Dark energy pulls every galaxy apart as it causes the universe to accelerate; dark energy is the opposing force, physicists think, which pushes galaxies back together. If this is correct, dark matter (which scientists are still searching for) could be losing its cosmic battle to hold things together, changing physics as we know it.

Image Credit: RedHeadsRule/Pixabay
Image Credit: RedHeadsRule/Pixabay

An Uncertain Outcome

The new results arose from the first observational season of the four-meter Victor M. Blanco Telescope. The observational period for the DES lasted only six months, but has already produced this strange result. The survey with the Blanco telescope will continue for five years, yielding more and better data as time passes.

Astronomers are rightly reluctant to come to overly dramatic conclusions based solely upon these initial data. From a statistical perspective, the variation between the early universe and the current version is slight. The mismatch may also disappear with more data, indicating that one or both of the measurements was incorrect.

However, this isn’t the only disparity; for example, results from the South Pole Telescope also conflict with the Planck data.

Although the scientific community has been assuming that the universe would continue to expand while galaxies would remain glued together, this may be wrong. If dark energy continues to increase, it’s possible that one day galaxies and everything inside them — down to atoms themselves — could expand enough to be torn apart.

As unsettling as that thought is, this may be yet another fascinating anomaly about our universe, with context that changes as we continue scanning the skies.

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The Largest Virtual Universe Ever Created Was Just Simulated in a Supercomputer

 

Studying The Cosmic Web

University of Zurich (UZH) researchers have simulated the way our Universe formed by creating the largest virtual universe with a large supercomputer. The team turned 2 trillion digital particles into around 25 billion virtual galaxies that together make up this virtual universe and galaxy catalogue. The catalogue will be used on the Euclid satellite, to be launched in 2020 to explore the nature of dark energy and dark matter, to calibrate the experiments.

“The nature of dark energy remains one of the main unsolved puzzles in modern science,” UZH professor of computational astrophysics Romain Teyssier said in a press release. Euclid will not be able to view dark matter or dark energy directly; the satellite will instead measure the tiny distortions of light of distant galaxies by invisible mass distributed in the foreground—dark matter. “That is comparable to the distortion of light by a somewhat uneven glass pane,” UZH Institute for Computational Science researcher Joachim Stadel said in the release.

Image Credit: Joachim Stadel/UZH
Image Credit: Joachim Stadel/UZH

Going Back In Time

The precise calculations that have allowed the team to create the virtual universe have also allowed them to simulate small concentrations of matter, dark matter halos, which may be the loci in which galaxies like ours form. The Euclid’s mission is to explore the dark side of the Universe, so part of the challenge of the virtual universe project was to accurately model galaxies only one-tenth the size of the Milky Way, within a massive volume the size of the observable Universe. The behavior observed in the virtual model will help Euclid know what to look for on its journey.

“Euclid will perform a tomographic map of our Universe, tracing back in time more than 10-billion-year of evolution in the cosmos,” Stadel said in the release. Researchers hope to learn more about dark energy from the Euclid data, but they are also eager to discover new areas of physics beyond the standard model, such as a new type of particle or a modified version of general relativity. Each bit of evidence along this journey may well take us one step closer to understanding the origins of our galaxy, and perhaps the entire Universe.

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New Explanation for Dark Energy? Tiny Fluctuations of Time and Space.

Since the late 1920s, astronomers have been aware of the fact that the Universe is in a state of expansion. Initially predicted by Einstein’s Theory of General Relativity, this realization has gone on to inform the most widely-accepted cosmological model — the Big Bang Theory. However, things became somewhat confusing during the 1990s, when improved observations showed that the Universe’s rate of expansion has been accelerating for billions of years.

This led to the theory of dark energy, a mysterious invisible force that is driving the expansion of the cosmos. Much like dark matter which explained the “missing mass,” it then became necessary to find this elusive energy, or at least provide a coherent theoretical framework for it. A new study from the University of British Columbia (UBC) seeks to do just that by postulating the Universe is expanding due to fluctuations in space and time.

The study — which was recently published in the journal Physical Review D – was led by Qingdi Wang, a PhD student with the Department of Physics and Astronomy at UBC. Under the supervisions of UBC Professor William Unruh (the man who proposed the Unruh Effect) and with assistance from Zhen Zhu (another PhD student at UBC), they provide a new take on dark energy.

Diagram showing the Lambda-CBR universe, from the Big Bang to the the current era. Image Credit: Alex Mittelmann/Coldcreation

The team began by addressing the inconsistencies arising out of the two main theories that together explain all natural phenomena in the Universe. These theories are none other than general relativity and quantum mechanics, which effectively explain how the Universe behaves on the largest of scales (i.e. stars, galaxies, clusters) and the smallest (subatomic particles).

Unfortunately, these two theories are not consistent when it comes to a little matter known as gravity, which scientists are still unable to explain in terms of quantum mechanics. The existence of dark energy and the expansion of the Universe are another point of disagreement. For starters, candidates theories like vacuum energy — which is one of the most popular explanations for dark energy — present serious incongruities.

According to quantum mechanics, vacuum energy would have an incredibly large energy density to it. But if this is true, then general relativity predicts that this energy would have an incredibly strong gravitational effect, one which would be powerful enough to cause the Universe to explode in size. As Prof. Unruh shared with Universe Today via email:

The problem is that any naive calculation of the vacuum energy gives huge values. If one assumes that there is some sort of cutoff so one cannot get energy densities much greater than the Planck energy density (or about 1095 Joules/meter³)  then one finds that one gets a Hubble constant — the time scale on which the Universe roughly doubles in size — of the order of 10-44 sec. So, the usual approach is to say that somehow something reduces that down so that one gets the actual expansion rate of about 10 billion years instead. But that ‘somehow’ is pretty mysterious and no one has come up with an even half convincing mechanism.

New Explanation for Dark Energy? Tiny Fluctuations of Time and Space.
Timeline of the Big Bang and the expansion of the Universe. Image Credit: NASA

Whereas other scientists have sought to modify the theories of general relativity and quantum mechanics in order to resolve these inconsistencies, Wang and his colleagues sought a different approach. As Wang explained to Universe Today via email:

Previous studies are either trying to modify quantum mechanics in some way to make vacuum energy small or trying to modify General Relativity in some way to make gravity numb for vacuum energy. However, quantum mechanics and General Relativity are the two most successful theories that explain how our Universe works… Instead of trying to modify quantum mechanics or General Relativity, we believe that we should first understand them better. We takes the large vacuum energy density predicted by quantum mechanics seriously and just let them gravitate according to General Relativity without modifying either of them.

For the sake of their study, Wang and his colleagues performed new sets of calculations on vacuum energy that took its predicted high energy density into account. They then considered the possibility that on the tiniest of scales — billions of times smaller than electrons — the fabric of spacetime is subject to wild fluctuations, oscillating at every point between expansion and contraction.

New Explanation for Dark Energy? Tiny Fluctuations of Time and Space.
Could fluctuations at the tiniest levels of space time explain Dark Energy and the expansion of the cosmos? Image Credit: University of Washington

As it swings back and forth, the result of these oscillations is a net effect where the Universe expands slowly, but at an accelerating rate. After performing their calculations, they noted that such an explanation was consistent with both the existence of quantum vacuum energy density and general relativity. On top of that, it is also consistent with what scientists have been observing in our Universe for almost a century. As Unruh described it:

Our calculations showed that one could consistently regard [that] the Universe on the tiniest scales is actually expanding and contracting at an absurdly fast rate; but that on a large scale, because of an averaging over those tiny scales, physics would not notice that ‘quantum foam.’ It has a tiny residual effect in giving an effective cosmological constant (dark energy type effect). In some ways it is like waves on the ocean which travel as if the ocean were perfectly smooth but really we know that there is this incredible dance of the atoms that make up the water, and waves average over those fluctuations, and act as if the surface was smooth.

In contrast to conflicting theories of a Universe where the various forces that govern it cannot be resolved and must cancel each other out, Wang and his colleagues presents a picture where the Universe is constantly in motion. In this scenario, the effects of vacuum energy are actually self-cancelling, and also give rise to the expansion and acceleration we have been observing all this time.

While it may be too soon to tell, this image of a Universe that is highly-dynamic (even on the tiniest scales) could revolutionize our understanding of spacetime. At the very least, these theoretical findings are sure to stimulate debate within the scientific community, as well as experiments designed to offer direct evidence. And that, as we know, is the only way we can advance our understanding of this thing known as the Universe.

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New Research Shows “68% of the Universe May Not Exist at All”

Dark Matter, Dark Energy

Dark energy” is believed to comprise 68 percent of the universe, but a Hungarian-American research team thinks it may not exist at all. The researchers believe that the concept of dark energy is merely filling in the gaps left by existing models of the universe, which fail to account for its changing structure. Once the model is corrected, the gaps disappear, and so does the need for dark energy within the model.

What Is Dark Matter?
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Our universe has been expanding ever since the Big Bang 13.8 billion years ago. Hubble’s law provides the key piece of evidence supporting this expansion. The law states that, on average, the distance between us and a given galaxy and its recessional velocity — the speed with which it moves away from us — are proportional. Astronomers observe the lines in a galaxy’s spectrum to measure the recessional velocity. The faster the galaxy moves away from us, the more the lines shift toward red. All of this led scientists to think that the entire universe is constantly expanding and that it must have begun as a vanishingly minuscule point.

Later, astronomers noticed that they needed something more to explain the motion of stars within galaxies and that brought upon the potential of unseen “dark matter.” Finally, after astronomers observed Type Ia supernovae, white dwarf stars exploding in binary systems, in the 1990s, they concluded that 68 percent of the cosmos is comprised of dark energy, which, along with about 5 percent ordinary matter and 27 percent dark matter, drives the expansion of the universe.

The new work, led by Eötvös Loránd University Phd student Gábor Rácz, suggests an alternative explanation for the expansion of the universe. The team argues that conventional cosmological models ignore the structure of the universe and rely on approximations. This leads to inevitable gaps in models, and that’s what dark energy has been sloppily used to fix.

Reframing the Debate

The team reconstructed the evolution of the universe using a computer simulation to model the ways that gravity affects the distribution of millions of dark matter particles. The reconstruction includes the formation of large scale structures and the early clumping of matter. Taking these structures into account produced a different simulation than conventional models, which show the universe expanding smoothly. This new simulation is consistent with previous models in that it shows an acceleration overall, but in it the expansion of the universe is uneven, with different regions within the cosmos expanding at different rates.

The research team argues that their work is based less on guesswork and more on sound modeling. Dr. László Dobos, co-author of the paper, explained the team’s approach to the Royal Astronomical Society:

We do not question [the validity of theory of general relativity]; 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 upheld, this work could impact future physics research and models of the universe significantly. For two decades, theoretical physicists and astronomers have speculated about the unsolved mystery of the nature of dark energy. With this revised model, an interesting new debate can begin.

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Scientists Think Dark Energy Might Be Just an Illusion

Dark Energy: Captivating and Confusing

Dark energy and matter, two hot-button subjects of physics that have captivated and stumped enthusiasts and experts alike. Since its discovery in 1998, dark energy has been a subject of extensive study and confusion. Theoretically comprising approximately 68% of the known universe, this mysterious form of energy is said to be accelerating the expansion of the Universe. However, despite these past conclusions, new simulations suggest that dark energy might not actually exist at all.

What Is Dark Matter?
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Physicists hailing from Loránd University in Hungary and the Institute for Astronomy at the University of Hawaii mathematically modeled the effect of gravity on “dark matter” (they used millions of particles to represent dark matter). This model showed how matter would have gathered and resembled large scale galaxy structures (or “bubbles” of space and their surrounding galaxies) in the early Universe. And, much like the actual Universe, their model expanded. However, averaging out how these different “bubbles” expanded, the researchers found an overall acceleration.

What Is the Universe Made Of?

Now, this might not seem like a huge deal, but when you think about this study in terms of dark energy, what they really found was an explanation for how the formation of large and complex structures in the universe affects its expansion. And, according to László Dobos from Eötvös Loránd University, “These issues were previously swept under the rug but taking them into account can explain the acceleration without the need for dark energy.”

Their calculations showed that dark energy could have really just been a tool to explain the expansion of the Universe. Dark energy could really just be an illusion of energy that comes from changing structures in the Universe. So…what does this mean? Well, for starters it means that there is both more and less mystery in our Universe. We might be a step closer to better understanding the expansion of the Universe, but this new possibility opens up a lot of new doors and introduces a lot of new questions.

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Why String Theory May Be the Key to Uncovering A “Theory of Everything”

Life, the Universe, and Everything

A central goal that modern physicists share is finding a single theory that can explain the entire universe and unite the forces of nature. The standard model, for example, leaves Dark Matter, Dark Energy, and even gravity out of the picture — meaning that it really only accounts for a very small percentage of what makes up the universe.

String Theory stitches Einstein’s conception of the general theory of relativity together with Quantum Mechanics, and the result is quantum theory applied to gravity. This application allows us to break down the universe beyond the subatomic particle level into vibrating strings whose interactions and vibrations make up the universe.

In other words, all matter is made up of atoms, and all atoms are composed of electrons, neutrons, and protons — and these can be broken down further into quarks. Quarks are are made up of these dynamic strings, whose motions in space are the key to understanding the universe, explained Michio Kaku, physicist at the City College of New York. Kaku is the He’s the co-founder of string field theory (a branch of string theory).

What is String Theory & How Does it Work?

Will A “Theory of Everything” Transform Our World?

Good Vibrations

In an interview with Big Think, Kaku explained String Theory this way: The standard model for physics, including the Higgs Boson, represents the lowest octave of a vibrating string. Dark matter, which makes up around 23 percent of the universe, is the next vibration up. Dark energy happens when the symmetries of the super string are broken, and it comprises about 68 percent of the universe.

So, according to String Theory, each vibrating string corresponds to a different particle, and there are almost certainly more dimensions to the universe than the four we once thought represented everything. String Theory is unique at this time because, as Kaku pointed out, it is the only game in town that truly has the potential to be a Theory of Everything.

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What Is Dark Matter?

Dark-matter_v2

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