Dark Energy Archives

January 10, 2014December 23, 2015 by Tammy Plotner

One Percent Measure of the Universe

An artist's concept of the latest, highly accurate measurement of the Universe from BOSS. The spheres show the current size of the "baryon acoustic oscillations" (BAOs) from the early universe, which have helped to set the distribution of galaxies that we see in the universe today. Galaxies have a slight tendency to align along the edges of the spheres — the alignment has been greatly exaggerated in this illustration. BAOs can be used as a "standard ruler" (white line) to measure the distances to all the galaxies in the universe. Credit: Zosia Rostomian, Lawrence Berkeley National Laboratory

When it comes to accuracy, everyone strives for a hundred percent, but measuring cosmic distances leaves a bit more to chance. Just days ago, researchers from the Baryon Oscillation Spectroscopic Survey (BOSS) announced to the world that they have been able to measure the distance to galaxies located more than six billion light-years away to a confidence level of just one percent. If this announcement doesn’t seem exciting, then think on what it means to other studies. These new measurements give a parameter to the properties of the ubiquitous “dark energy” – the source of universal expansion.

“There are not many things in our daily lives that we know to one-percent accuracy,” said David Schlegel, a physicist at Lawrence Berkeley National Laboratory (LBNL) and the principal investigator of BOSS. “I now know the size of the universe better than I know the size of my house.”

The research team’s findings were presented at the meeting of the American Astronomical Society by Harvard University astronomer Daniel Eisenstein, the director of the Sloan Digital Sky Survey III (SDSS-III), the worldwide organization which includes BOSS. They are detailed in a series of articles submitted to journals by the BOSS collaboration last month, all of which are now available as online preprints.

“Determining distance is a fundamental challenge of astronomy,” said Eisenstein. “You see something in the sky — how far away is it? Once you know how far away it is, learning everything else about it is suddenly much easier.”

When it comes to measuring distances in space, astronomers have employed many methods. To measure distances to planets has been accomplished using radar, but it has its constraints and going further into space means a less direct method. Even though they have been proved to be amazingly accurate, there is still an uncertainty factor involved – one that is expressed as a percentage. For example, if you were to measure the distance from an object 200 miles away to within a true value of 2 miles, then you have measured with an accuracy of 1%. Cosmically speaking, just a few hundred stars and a handful of star clusters are actually close enough to have their distances so accurately predicted. They reside within the Milky Way and are just a few thousand light-years away. BOSS takes it to the extreme… its measurements go well beyond our galactic boundaries, more than a million times further, and maps the Universe with unparalleled accuracy.

Thanks to these new, highly-accurate distance measurements, BOSS astronomers are making headway in the field of dark energy. “We don’t yet understand what dark energy is,” explained Eisenstein, “but we can measure its properties. Then, we compare those values to what we expect them to be, given our current understanding of the universe. The better our measurements, the more we can learn.”

Just how is it done? To achieve a one-percent measurement at six billion light years isn’t as easy as measuring a solar system object, or even one contained within our galaxy. That’s where the BOSS comes into play. It’s the largest of the four projects that make up the Sloan Digital Sky Survey III (SDSS-III), and was built to take advantage of this technique: measuring the so-called “baryon acoustic oscillations” (BAOs), subtle periodic ripples in the distribution of galaxies in the cosmos. These ripples are the signature of pressure waves which once cruised the early Universe at a time when things were so hot and dense that photons marched along with baryons – the stuff which creates the nuclei of atoms. Since the size of the ripple is known, that size can now be measured by mapping galaxies.

“With these galaxy measurements, nature has given us a beautiful ruler,” said Ashley Ross, an astronomer from the University of Portsmouth. “The ruler happens to be half a billion light-years long, so we can use it to measure distances precisely, even from very far away.

Using its specialized instrumentation which can make detailed measurements of a thousand galaxies at a time, BOSS took on a huge challenge – mapping the location of more than a million galaxies. “On a clear night when everything goes perfectly, we can add more than 8000 galaxies and quasars to the map,” said Kaike Pan, who leads the team of observers at the SDSS-III’s Sloan Foundation 2.5-meter Telescope at Apache Point Observatory in New Mexico.

Although the BOSS research team presented its early galaxy maps and beginning BAO measurements a year ago, this new data covers twice as much territory and gives an even more accurate measurement – including those to nearby galaxies. “Making these measurements at two different distances allows us to see how the expansion of the universe has changed over time, which will help us understand why it is accelerating,” explained University of Portsmouth astronomer Rita Tojeiro, who co-chairs the BOSS galaxy clustering working group along with Jeremy Tinker of New York University.

Also doing a similar study is Mariana Vargas-Magana, a postdoctoral researcher at Carnegie Mellon University. To enable even more accuracy, she’s looking into any subtle effects which could influence the BOSS measurements. “When you’re trying to reach one percent, you have to be paranoid about everything that could go even slightly wrong,” said Vargas-Magana — for example, slight differences in how galaxies were identified could have thrown off the entire measurement of their distribution, so different parts of the sky had to be checked carefully. “Fortunately,” Vargas-Magana said, “there are plenty of careful people on our team to check our assumptions. By the time all of them are satisfied, we are sure we didn’t miss anything.”

As of the present, these new BOSS findings would seem to be consistent with what we consider to be form of dark energy – a constant found throughout the history of the Universe. According to the news release, this “cosmological constant” is one of just six numbers required to create a model which coincides with the scale and structure of the Universe. Schlegel compares this six-number model to a pane of glass, which is pinned in place by bolts that represent different measurements of the history of the Universe. “BOSS now has one of the tightest of those bolts, and we just gave it another half-turn,” said Schlegel. “Each time you ratchet up the tension and the glass doesn’t break, that’s a success of the model.”

Original Story Source: Sloan Digital Sky Survey III News Release. For further reading: Max Planck Institute News Release.

October 30, 2013April 26, 2016 by Elizabeth Howell

New Dark Matter Detector Draws A Blank In First Test Round

Dark Energy — The Hubble Space Telescope image of the inner regions of the lensing cluster Abell 1689 that is 2.2 billion light?years away. Light from distant background galaxies is bent by the concentrated dark matter in the cluster (shown in the blue overlay) to produce the plethora of arcs and arclets that were in turn used to constrain dark energy. Image courtesy of NASA?ESA, Jullo (JPL), Natarajan (Yale), Kneib (LAM)

We keep saying dark matter is so very hard to find. Astronomers say they can see its effects — such as gravitational lensing, or an amazing bendy feat of light that takes place when a massive galaxy brings forward light from other galaxies behind it. But defining what the heck that matter is, is proving elusive. And considering it makes up most of the universe’s matter, it would be great to know what dark matter looks like.

A new experiment — billed as the most sensitive dark matter detector in the world — spent three months searching for evidence of weakly interacting massive particles (WIMPs), which may be the basis of dark matter. So far, nothing, but researchers emphasized they have only just started work.

“Now that we understand the instrument and its backgrounds, we will continue to take data, testing for more and more elusive candidates for dark matter,” stated physicist Dan McKinsey of Yale University, who is one of the collaborators on the Large Underground Xenon (LUX) detector.

A view of the Large Underground Xenon (LUX) dark matter detector. Shown are photomultiplier tubes that can ferret out single photons of light. Signals from these photons told physicists that they had not yet found Weakly Interacting Massive Particles (WIMPs) Credit: Matthew Kapust / South Dakota Science and Technology Authority

LUX operates a mile (1.6 kilometers) beneath the Earth in the state-owned Sanford Underground Research Facility, which is located in South Dakota. The underground location is perfect for this kind of work because there is little interference from cosmic ray particles.

“At the heart of the experiment is a six-foot-tall titanium tank filled with almost a third of a ton of liquid xenon, cooled to minus 150 degrees Fahrenheit. If a WIMP strikes a xenon atom it recoils from other xenon atoms and emits photons (light) and electrons. The electrons are drawn upward by an electrical field and interact with a thin layer of xenon gas at the top of the tank, releasing more photons,” stated the Lawrence Berkeley National Laboratory, which leads operations at Sanford.

“Light detectors in the top and bottom of the tank are each capable of detecting a single photon, so the locations of the two photon signals – one at the collision point, the other at the top of the tank – can be pinpointed to within a few millimeters. The energy of the interaction can be precisely measured from the brightness of the signals.”

The densest regions of the dark matter cosmic web host massive clusters of galaxies. Credit: Van Waerbeke, Heymans, and CFHTLens collaboration.

LUX’s sensitivity for low-mass WIMPs is more than 20 times better than other detectors. That said, the detector was unable to confirm possible hints of WIMPs found in other experiments.

“Three candidate low-mass WIMP events recently reported in ultra-cold silicon detectors would have produced more than 1,600 events in LUX’s much larger detector, or one every 80 minutes in the recent run,” the laboratory added.

Don’t touch that dial yet, however. LUX plans to do more searching in the next two years. Also, the Sanford Lab is proposing an even more sensitive LUX-ZEPLIN experiment that would be 1,000 times more sensitive than LUX. No word yet on when LUX-ZEPLIN will get off the ground, however.

Source: Lawrence Berkeley National Laboratory

June 28, 2013July 16, 2020 by Jason Major

An “Elemental” Explanation of Dark Matter

Image from Dark Universe, showing the distribution of dark matter in the universe. Credit: AMNH

Atoms, string theory, dark matter, dark energy… there’s an awful lot about the Universe that might make sense on paper (to physicists, anyway) but is extremely difficult to detect and measure, at least with the technology available today. But at the core of science is observation, and what’s been observed of the Universe so far strongly indicates an overwhelming amount of… stuff… that cannot be observed. But just because it can’t be seen doesn’t mean it’s not there; on the contrary, it’s what we can’t see that actually makes up the majority of the Universe.

If this doesn’t make sense, that’s okay — they’re all pretty complex concepts. So in order to help non-scientists (which, like dark energy, most of the population is comprised of) get a better grasp as to what all this “dark” stuff is about, CERN scientist and spokesperson James Gillies has teamed up with TED-Ed animators to visually explain some of the Universe’s darkest secrets. Check it out above (and see more space science lessons from TED-Ed here.)

Because everything’s easier to understand with animation!

Lesson by James Gillies, animation by TED-Ed.

June 7, 2013December 23, 2015 by Ken Kremer

Spectacular Night Launch from NASA Wallops Shines Bright Beacon on Star Formation in Early Universe

Night time blast off of 4 stage NASA Black Brant XII suborbital rocket at 11:05 p.m. EDT on June 5, 2013 from the NASA Wallops Flight Facility carrying the CIBER astronomy payload to study when the first stars and galaxies formed in the universe. The Black Brant soars above huge water tower at adjacent Antares rocket launch pad at NASA Wallops. Credit: Ken Kremer- kenkremer.com
Updated with more photos[/caption]

WALLOPS ISLAND, VA – The spectacular night time launch of a powerful Black Brant XII suborbital rocket from NASA’s launch range at the Wallops Flight Facility on Virginia’s Eastern Shore at 11:05 p.m. June 5 turned darkness into day as the rocket swiftly streaked skyward with the Cosmic Infrared Background ExpeRiment (CIBER) on a NASA mission to shine a bright beacon for science on star and galaxy formation in the early Universe.

A very loud explosive boom shook the local launch area at ignition that was also heard by local residents and tourists at distances over 10 miles away, gleeful spectators told me.

“The data looks good so far,” Jamie Bock, CIBER principal investigator from the California Institute of Technology, told Universe Today in an exclusive post-launch interview inside Mission Control at NASA Wallops. “I’m very happy.”

Ignition of NASA Black Brant XII suborbital rocket following night time launch at 11:05 p.m. EDT on June 5, 2013 from the NASA Wallops Flight Facility at the eastern Virginia shoreline. The launch pad sits in front of the Antares rocket Launch Complex 0A dominated by the huge water tower. The rocket carried the CIBER astronomy payload to an altitude of approximately 358 miles above the Atlantic Ocean to study when the first stars and galaxies formed in the universe and how brightly they burned their nuclear fuel. Credit: Ken Kremer- kenkremer.com

The four stage Black Brant XII is the most powerful sounding rocket in America’s arsenal for scientific research.

“I’m absolutely thrilled with this launch and this is very important for Wallops,” William Wrobel, Director of NASA Wallops Flight Facility, told me in an exclusive interview moments after liftoff.

Wallops is rapidly ramping up launch activities this year with two types of powerful new medium class rockets – Antares and Minotaur V- that can loft heavy payloads to the International Space Station (ISS) and to interplanetary space from the newly built pad 0A and the upgraded, adjacent launch pad 0B.

“We have launched over 16,000 sounding rockets.”

“Soon we will be launching our first spacecraft to the moon, NASA’s LADEE orbiter. And we just launched the Antares test flight on April 21.”

I was delighted to witness the magnificent launch from less than half a mile away with a big group of cheering Wallops employees and Wallops Center Director Wrobel. See my launch photos and time lapse shot herein.

Everyone could hear piercing explosions as each stage of the Black Brant rocket ignited as it soared to the heavens to an altitude of some 358 miles above the Atlantic Ocean.

Seconds after liftoff we could see what looked like a rain of sparkling fireworks showing downward towards the launch pad. It was a fabulous shower of aluminum slag and spent ammonium perchlorate rocket fuel.

A powerful NASA Black Brant XII suborbital rocket streaks into the night sky following its launch at 11:05 p.m. EDT on June 5, 2013 from the NASA Wallops Flight Facility at the eastern Virginia shoreline. The launch pad sits in front of the Antares rocket Launch Complex 0A dominated by the huge water tower. The rocket carried the Cosmic Infrared Background ExpeRiment (CIBER) to an altitude of approximately 358 miles above the Atlantic Ocean to study when the first stars and galaxies formed in the universe and how brightly they burned their nuclear fuel. Credit: Ken Kremer - kenkremer.com — A powerful NASA Black Brant XII suborbital rocket streaks spectacularly into the night sky following its launch at 11:05 p.m. EDT on June 5, 2013 from the NASA Wallops Flight Facility at the eastern Virginia shoreline. The launch pad sits in front of the Antares rocket Launch Complex 0A dominated by the huge water tower. The rocket carried the Cosmic Infrared Background ExpeRiment (CIBER) to an altitude of approximately 358 miles above the Atlantic Ocean to study when the first stars and galaxies formed in the universe and how brightly they burned their nuclear fuel. Side firing thrusters have ignited to impart stabilizing spin as rocket ascends above launch rail. Credit: Ken Kremer- kenkremer.com

The awesome launch took place on a perfectly clear night drenched with brightly shining stars as the Atlantic Ocean waves relentlessly pounded the shore just a few hundred feet away.

The rocket zoomed past the prominent constellation Scorpius above the Atlantic Ocean.

In fact we were so close that we could hear the spent first stage as it was plummeting from the sky and smashed into the ocean, perhaps 10 miles away.

After completing its spectral collection to determine when did the first stars and galaxies form and how brightly did they shine burning their nuclear fuel, the CIBER payload splashed down in the Atlantic Ocean and was not recovered.

Time lapse view of night launch of NASA Black Brant XII suborbital rocket zooming past constellation Scorpius (left) at 11:05 p.m. EDT above Atlantic Ocean on June 5, 2013 from the NASA Wallops Flight Facility carrying the CIBER astronomy payload. Credit: Ken Kremer- kenkremer.com

Night time launch of NASA Black Brant XII suborbital rocket at 11:05 p.m. EDT on June 5, 2013 from the NASA Wallops Flight Facility carrying the CIBER astronomy payload. Credit: Ken Kremer- kenkremer.com

NASA said the launch was seen from as far away as central New Jersey, southwestern Pennsylvania and northeastern North Carolina.

One of my astronomy friends Joe Stieber, did see the launch from about 135 miles away in central New Jersey and captured beautiful time lapse shots (see below).

Time lapse view of June 5 launch of Blank Brant XII sounding rocket from Wallops Island as seen from Carranza Field in Wharton State Forest, NJ (about 135 miles north from Wallops). Scorpius is above the trees at the far left. Credit: Joe Stieber- sjastro.com

Everything with the rocket and payload went exactly as planned.

“This was our fourth and last flight of the CIBER payload,” Bock told me. “We are still analyzing data from the last 2 flights.”

“CIBER first flew in 2009 atop smaller sounding rockets launched from White Sands Missile Range, N.M. and was recovered.”

“On this flight we wanted to send the experiment higher than ever before to collect more measurements for a longer period of time to help determine the brightness of the early Universe.”

CIBER is instrumented with 2 cameras and 2 spectrometers.

“The payload had to be cooled to 84 Kelvin with liquid nitrogen before launch in order for us to make the measurements,” Bock told me.

“The launch was delayed a day from June 4 because of difficulty both in cooling the payload to the required temperature and in keeping the temperature fluctuations to less than 100 microkelvins,” Bock explained

The CIBER experiment involves scientists and funding from the US and NASA, Japan and South Korea.

Bock is already thinking about the next logical steps with a space based science satellite.

Space.com has now featured an album of my CIBER launch photos – here

Night launch of NASA Black Brant XII suborbital rocket at 11:05 p.m. EDT on June 5, 2013 from NASA Wallops Flight Facility, VA carrying CIBER astronomy payload. Credit: Ken Kremer

And don’t forget to “Send Your Name to Mars” aboard NASA’s MAVEN orbiter- details here. Deadline: July 1, 2013

Ken Kremer

…………….
Learn more about Conjunctions, Mars, Curiosity, Opportunity, MAVEN, LADEE and NASA missions at Ken’s upcoming lecture presentations

June 11: “Send your Name to Mars on MAVEN” and “LADEE Lunar & Antares Rocket Launches from Virginia”; NJ State Museum Planetarium and Amateur Astronomers Association of Princeton (AAAP), Trenton, NJ, 730 PM.

June 12: “Send your Name to Mars on MAVEN” and “LADEE Lunar & Antares Rocket Launches from Virginia”; Franklin Institute and Rittenhouse Astronomical Society, Philadelphia, PA, 8 PM.

June 23: “Send your Name to Mars on MAVEN” and “CIBER Astro Sat, LADEE Lunar & Antares Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8 PM

Aerial view of NASA Wallops launch site on Virginia shore shows launch pads for both suborbital and orbital rockets. This photo was snapped from on top of Pad 0B that will soon launch NASA‘s LADEE orbiter to the Moon. Credit: Ken Kremer- kenkremer.com — Aerial view of NASA Wallops launch site on Virginia shore shows launch pads for both suborbital and orbital rockets. CIBER’s Black Brant XII rocket blasted off just behind the Pad 0A water tower. This photo was snapped from on top of Pad 0B that will soon launch NASA‘s LADEE orbiter to the Moon. Credit: Ken Kremer- kenkremer.com

NASA Time lapse view shows multiple stages firing during night launch of NASA Black Brant XII suborbital rocket at 11:05 p.m. EDT above Atlantic Ocean on June 5, 2013 from the NASA Wallops Flight Facility carrying the CIBER astronomy payload. Credit: NASA/Jamie Adkins

NASA Black Brant XII suborbital rocket streaks skyward after blastoff at 11:05 p.m. EDT on June 5, 2013 from NASA Wallops Flight Facility, VA carrying CIBER astronomy payload. Credit: Ken Kremer

June 4, 2013December 23, 2015 by Ken Kremer

NASA Experiment Seeks Signatures of Formation of First Stars and Galaxies

NASA’s CIBER experiment seeks clues to the formation of the first stars and galaxies. It will study the total sky brightness, to probe the component from first stars and galaxies using spectral signatures, and searches for the distinctive spatial pattern seen in this image, produced by large-scale structures from dark matter. This shows a numerical simulation of the density of matter when the universe was one billion years old. Galaxies formation follows the gravitational wells produced by dark matter, where hydrogen gas coalesces, and the first stars ignite. Credit: Volker Springel/Virgo Consortium.

When did the first stars and galaxies form in the universe and how brightly did they burn?

Scientists are looking for tell-tale signs of galaxy formation with an experimental payload called CIBER.

NASA will briefly turn night into day near midnight along the mid-Atlantic coastline on June 4 – seeking answers to illuminate researchers theories about the beginnings of our Universe with the launch of the Cosmic Infrared Background ExpeRiment (CIBER) from NASA’s launch range at the Wallops Flight Facility along Virginia’s eastern shoreline. See viewing map below.

CIBER will blast off atop a powerful four stage Black Brant XII suborbital rocket at 11 PM EDT Tuesday night, June 4. The launch window extends until 11:59 PM EDT.

Currently the weather forecast is excellent.

The public is invited to observe the launch from an excellent viewing site at the NASA Visitor Center at Wallops which will open at 9:30 PM on launch day.

The night launch will be visible to spectators along a long swath of the US East coast from New Jersey to North Carolina; if the skies are clear as CIBER ascends to space to an altitude of over 350 miles and arcs over on a southeasterly trajectory.

Backup launch days are available from June 5 through 10.

Launch visibility map for the CIBER payload launch from NASA Wallops, Va, on June 4, 2013 at 11 PM EDT. Credit: NASA

“The objectives of the experiment are of fundamental importance for astrophysics: to probe the process of first galaxy formation. The measurement is extremely difficult technically,” said Jamie Bock, CIBER principal investigator from the California Institute of Technology

Over the past several decades more than 20,000 sounding rockets have blasted off from an array of launch pads at Wallops, which is NASA’s lead center for suborbital science.

The Black Brant XII sounding rocket is over 70 feet tall.

The launch pad sits adjacent to the newly constructed Pad 0A of the Virginia Spaceflight Authority from which the Orbital Sciences Antares rocket blasted off on its maiden flight on April 21, 2013.

“The first massive stars to form in the universe produced copious ultraviolet light that ionized gas from neutral hydrogen. CIBER observes in the near infrared, as the expansion of the universe stretched the original short ultraviolet wavelengths to long near-infrared wavelengths today.”

“CIBER investigates two telltale signatures of first star formation — the total brightness of the sky after subtracting all foregrounds, and a distinctive pattern of spatial variations,” according to Bock.

Preparing the CIBER instrument for flight. The optics and detectors are cooled by liquid nitrogen to -19C (77 K, -312F) during the flight to eliminate infrared emission from the instrument and to achieve the best detector sensitivity. Photo: NASA/Berit Bland

This will be the fourth launch of CIBER since 2009 but the first from Wallops. The three prior launches were all from the White Sands Missile Range, N.M. and in each case the payload was recovered and refurbished for reflight.

However the June 4 launch will also be the last hurrah for CIBER.

The scientists are using a more powerful Black Brant rocket to loft the payload far higher than ever before so that it can make measurements for more than twice as long as ever before.

The consequence of flying higher is that CIBER will splashdown in the Atlantic Ocean, about 400 miles off the Virgina shore and will not be recovered.

You can watch the launch live on NASA Ustream beginning at 10 p.m. on launch day at: http://www.ustream.com/channel/nasa-wallops

I will be onsite at Wallops for Universe Today.

And don’t forget to “Send Your Name to Mars” aboard NASA’s MAVEN orbiter- details here. Deadline: July 1, 2013

Ken Kremer

…………….
Learn more about Conjunctions, Mars, Curiosity, Opportunity, MAVEN, LADEE and NASA missions at Ken’s upcoming lecture presentations

June 4: “Send your Name to Mars on MAVEN” and “CIBER Astro Sat, LADEE Lunar & Antares Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8:30 PM

June 12: “Send your Name to Mars on MAVEN” and “LADEE Lunar & Antares Rocket Launches from Virginia”; Franklin Institute and Rittenhouse Astronomical Society, Philadelphia, PA, 8 PM.

NASA’s CIBER payload will launch from a suborbital launch pad located directly behind this Antares rocket erected at Pad 0A at the NASA Wallops Flight Facility along the Eastern shore of Virginia. Only a few hundred feet of beach sand and a miniscule sea wall separate the Wallops Island pads from the Atlantic Ocean waves and Mother Nature. Credit: Ken Kremer (kenkremer.com) — NASA’s CIBER payload will launch from a suborbital launch pad located directly behind this Antares rocket erected at Pad 0A at the NASA Wallops Flight Facility along the Eastern shore of Virginia. Only a few hundred feet of beach sand and a miniscule sea wall separate the Wallops Island pads from the Atlantic Ocean waves and Mother Nature.
Credit: Ken Kremer (kenkremer.com)

December 7, 2012April 26, 2016 by Jason Major

Do We Really Need Dark Matter?

Hubble mosaic of massive galaxy cluster MACS J0717.5+3745, thought to be connected by a filament of dark matter. Credit: NASA, ESA, Harald Ebeling (University of Hawaii at Manoa) & Jean-Paul Kneib (LAM)

Even though teams of scientists around the world are at this very moment hot on the trail of dark matter — the “other stuff” that the Universe is made of and supposedly accounts for nearly 80% of the mass that we can’t directly observe (yet) — and trying to quantify exactly how so-called “dark energy” drives its ever-accelerating expansion, perhaps one answer to these ongoing mysteries is maybe they don’t exist at all.

This is precisely what one astronomer is suggesting in a recent paper, submitted Dec. 3 to Astrophysical Journal Letters.

In a paper titled “An expanding universe without dark matter and dark energy” (arXiv:1212.1110) Pierre Magain, a professor at Belgium’s Institut d’Astrophysique et de Géophysique, proposes that the expansion of the Universe could be explained without the need for enigmatic material and energy that, to date, has yet to be directly measured.

In addition, Magain’s proposal puts a higher age to the Universe than what’s currently accepted. With a model that shows a slower expansion rate during the early Universe than today, Magain’s calculations estimate its age to be closer to 15.4 – 16.5 billion years old, adding a couple billion more candles to the cosmic birthday cake.

The benefit to a slightly older Universe, Magain posits, is that it’s not so uncannily close to the apparent age of the most distant galaxies recently found — such as MACS0647-JD, which is 13.3 billion light-years away and thus (based on current estimates, see graphic at right) must have formed when the Universe was a mere 420 million years old.

Using accepted physics of how time behaves based on Einstein’s theory of general relativity — namely, how the passage of time is relative to the position and velocity of the viewer (as well as the intensity of the gravitational field the viewer is within) — Magain’s model allows for an observer located within the Universe to potentially be experiencing a different rate of time than a hypothetical viewer located outside the Universe. Not to be so metaphysical as to presume that there are external observers of our Universe but merely to say that an external point would be a fixed one against which one could benchmark a varying passage of time inside the Universe, Magain calls this universal relativity.

A viewer experiencing universal relativity would, Magain claims, always measure the curvature of the Universe to be equal to zero. This is what’s currently observed, a “flatness problem” that Magain insinuates is strangely coincidental.

By attributing an expanding Universe to dark energy and the high velocities of stars along the edges of galaxies (as well as the motions of galaxy clusters themselves) to dark matter, we may be introducing ad hoc elements to the Universe, says Magain. Instead, he proposes his “more economical” model — which uses universal relativity — explains these apparently accelerating, increasingly expanding behaviors… and gives a bigger margin of time between the Big Bang and the formation of the first galactic structures.

There’s quite a bit of math involved, and since I never claimed to understand physics equations you can check out the original paper here.

While intriguing, the bottom line is that dark energy and dark matter have still managed to elude science, existing just outside the borders of what can be observed (although the gravitational lensing effects of what’s thought to be dark matter filaments have been observed by Hubble) and Magain’s paper is merely putting another idea onto the table — one that, while he recognizes needs further testing and relies upon very specific singular parameters, doesn’t depend upon invisible, unobservable and mysteriously dark “stuff”. Whether it belongs on the table or not will be up to other astrophysicists to decide.

Prof. Magain’s research was supported by ESA and the Belgian Science Policy Office.

At right: Artist’s impression of dark matter (h/t to Steve Nerlich)

Note: this is “just” a submitted paper and has not been selected for publication yet. Any hypotheses proposed are those of the author and are not endorsed by this site. (Personally I like dark matter. It’s fascinating stuff… even if we can’t see it. Want an astrophysicist’s viewpoint on the existence of dark matter? Check out Ethan Siegel’s blog response here.)

October 12, 2012December 23, 2015 by Nancy Atkinson

Can a New Camera Unravel the Nature of Dark Energy?

The 570 megapixel Dark Energy Camera. Credit: Fermilab

Scientists have great expectations for the newly operational Dark Energy Camera, which may significantly advance our understanding of the mysterious force expanding the Universe at an ever accelerating rate. Find out more about this highly anticipated new camera and what it is expected to reveal during live webcast from the Kavli Foundation. You’ll be able to ask questions to Fermilab scientists Brenna Flaugher, project manager for the Dark Energy Camera, and Joshua Frieman, director of the Dark Energy Survey. The webcast will be on October 12, 10-10:30 am PDT (17:30 UTC). Viewers may submit questions via Twitter using the #KavliAstro hashtag, or email to [email protected].

Watch the webcast below, or at this link.

If you miss the webcast live, afterwards you’ll be able to watch a replay on the player below, as well.

The new camera is mounted on the Blanco 4-meter telescope at the National Science Foundation’s Cerro Tolollo InterAmerican Observatory (CTIO) in Chile.

It is the widest field optical imager in astronomy today, and is capable of detecting light from over 100,000 galaxies up to 8 billion light years away. The instrument is composed of an array of 62 charged-coupled devices, and new technology will allow scientists from around the world to investigate the studies of asteroids in our solar system to the understanding of the origins and the fate of the Universe.

It is expected that in just over five years, astronomers will be able to create detailed color images of one-eighth of the sky, to discover and measure 300 million galaxies, 100,000 galaxy clusters and 4,000 supernovae.

“The Dark Energy Camera will solve the mystery of dark energy in a systematic manner,” said Andrea Kunder of CTIO in a podcast on 365 Days of Astronomy. “The idea is to observe four different probes of dark energy. You can’t see dark energy so there are four different probes of dark energy that DECam will be observing. First, DECam will observe type Ia supernova and baryon acoustic oscillations and this will be to constrain the expansion of the universe. And then galaxy clusters and weak lensing will also be observed to measure both the expansion of the universe and the growth of large scale structures. Then we can compare the results from these first two probes and the last two probes and this can reveal our understanding of gravity and intercomparisons of the results will provide cross checks and bolster confidence in the findings.”

September 17, 2012December 23, 2015 by Jason Major

First Images in a New Hunt for Dark Energy

Zoomed-in image from the Dark Energy Camera of the barred spiral galaxy NGC 1365, about 60 million light-years from Earth. (Dark Energy Survey Collaboration)

The ongoing search for dark energy now has a new set of eyes: the Dark Energy Camera, mounted on the 4-meter Victor M. Blanco telescope at the National Science Foundation’s Cerro Tololo Inter-American Observatory in Chile. The culmination of eight years of planning and engineering, the phone-booth-sized 570-megapixel Dark Energy Camera has now gathered its very first images, capturing light from cosmic structures tens of millions of light-years away.

Eventually the program’s survey will help astronomers uncover the secrets of dark energy — the enigmatic force suspected to be behind the ongoing and curiously accelerating expansion of the Universe.

Zoomed-in image from the Dark Energy Camera of the Fornax cluster

“The Dark Energy Survey will help us understand why the expansion of the universe is accelerating, rather than slowing due to gravity,” said Brenna Flaugher, project manager and scientist at Fermilab.

The most powerful instrument of its kind, the Dark Energy Camera will be used to create highly-detailed color images of a full 1/8th of the night sky — about 5,000 square degrees — surveying thousands of supernovae, galactic clusters and literally hundreds of millions of galaxies, peering as far away as 8 billion light-years.

The survey will attempt to measure the effects of dark energy on large-scale cosmic structures, as well as identify its gravitational lensing effects on light from distant galaxies. The images seen here, acquired on September 12, 2012, are just the beginning… the Dark Energy Survey is expected to begin actual scientific investigations this December.

Full Dark Energy Camera composite image of the Small Magellanic Cloud

“The achievement of first light through the Dark Energy Camera begins a significant new era in our exploration of the cosmic frontier,” said James Siegrist, associate director of science for high energy physics with the U.S. Department of Energy. “The results of this survey will bring us closer to understanding the mystery of dark energy, and what it means for the universe.”

Read more on the Symmetry Magazine article here, and you can also follow the Dark Energy Survey on Facebook here. (The Fermilab press release can be found here.)

Images: Dark Energy Survey Collaboration. Inset image: the 4-meter Blanco Telescope dome at CTIO (NOAO)

The Dark Energy Survey is supported by funding from the U.S. Department of Energy; the National Science Foundation; funding agencies in the United Kingdom, Spain, Brazil, Germany and Switzerland; and the participating DES institutions.

June 21, 2012December 23, 2015 by Jenny Winder

Euclid and the Geometry of the Dark Universe

Artist’s impression of Euclid Credit: ESA/C. Carreau

Euclid, an exciting new mission to map the geometry, distribution and evolution of dark energy and dark matter has just been formally adopted by ESA as part of their Cosmic Vision 2015-2025 progamme. Named after Euclid of Alexandria, the “Father of Geometry”, it will accurately measure the accelerated expansion of the Universe, bringing together one of the largest collaborations of astronomers, engineers and scientists in an attempt to answer one of the most important questions in cosmology: why is the expansion of the Universe accelerating, instead of slowing down due to the gravitational attraction of all the matter it contains?

In 2007 the Hubble Space Telescope produced a 3D map of dark matter that covered just over 2 square degrees of sky, while in March this year the Baryon Oscillation Spectroscopic Survey (BOSS) measured the precise distance to just over a quarter of a million galaxies. Working in the visible and near-infrared wavelengths, Euclid will precisely measure around two billion galaxies and galaxy clusters in 3 dimensions in a wide extragalactic survey covering 15,000 square degrees (over a third of the sky) plus a deep survey out to redshifts of ~2, covering an area of 40 square degrees, the 3-D galaxy maps produced will trace dark energy’s influence over 10 billion years of cosmic history, covering the period when dark energy accelerated the expansion of the Universe.

The mission was selected last October but now that it has been formally adopted by ESA, invitations to tender will be released, with Astrium and Thales Alenia Space, Europe’s two main space companies expected to bid. Hoping to launch in 2020, Euclid will involve contributions from 11 European space agencies as well as NASA while nearly 1,000 scientists from 100 institutes form the Euclid Consortium building the instruments and participating in the scientific harvest of the mission. It is expected to cost around 800m euros ($1,000m £640m) to build, equip, launch and operate over its nominal 6 year mission lifetime, where it will orbit the second Sun-Earth Lagrange point (L2 in the image below) It will have a mass of around 2100 kg, and measure about 4.5 metres tall by 3.1 metres. It will carry a 1.2 m Korsch telescope, a near infrared camera/spectrometer and one of the largest optical digital cameras ever flown in space.

Dark matter represents 20% of the universe and dark energy 76%. Euclid will use two techniques to map the dark matter and measure dark energy. Weak gravitational lensing measures the distortions of light from distant galaxies due to the mass of dark matter, this requires extremely high image quality to suppress or calibrate-out image distortions in order to measure the true distortions by gravity. Euclid’s camera will produce images 100 times larger than those produced by Hubble, minimizing the need to stitch images together. Baryonic acoustic oscillations, wiggle patterns, imprinted in the clustering of galaxies, will provide a standard ruler to measure dark energy and the expansion in the Universe. This involves the determination of the redshifts of galaxies to better than 0.1%. It is also hoped that later in the mission, supernovas may be used as markers to measure the expansion rate of the Universe.

Find out more about Euclid and other Cosmic Vision missions at ESA Science

Lead image caption: Artist’s-impression-of-Euclid-Credit-ESA-C.-Carreau

Second image caption: Sun Earth Lagrange Points Credit: Xander89 via Wikimedia Commons

April 5, 2012April 26, 2016 by Jason Major

Polar Telescope Casts New Light On Dark Energy And Neutrino Mass

The 10-meter South Pole Telescope in Antarctica at the Amundsen-Scott Station. (Daniel Luong-Van, National Science Foundation)

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Located at the southermost point on Earth, the 280-ton, 10-meter-wide South Pole Telescope has helped astronomers unravel the nature of dark energy and zero in on the actual mass of neutrinos — elusive subatomic particles that pervade the Universe and, until very recently, were thought to be entirely without measureable mass.

The NSF-funded South Pole Telescope (SPT) is specifically designed to study the secrets of dark energy, the force that purportedly drives the incessant (and apparently still accelerating) expansion of the Universe. Its millimeter-wave observation abilities allow scientists to study the Cosmic Microwave Background (CMB) which pervades the night sky with the 14-billion-year-old echo of the Big Bang.

Overlaid upon the imprint of the CMB are the silhouettes of distant galaxy clusters — some of the most massive structures to form within the Universe. By locating these clusters and mapping their movements with the SPT, researchers can see how dark energy — and neutrinos — interact with them.

“Neutrinos are amongst the most abundant particles in the universe,” said Bradford Benson, an experimental cosmologist at the University of Chicago’s Kavli Institute for Cosmological Physics. “About one trillion neutrinos pass through us each second, though you would hardly notice them because they rarely interact with ‘normal’ matter.”

If neutrinos were particularly massive, they would have an effect on the large-scale galaxy clusters observed with the SPT. If they had no mass, there would be no effect.

The SPT collaboration team’s results, however, fall somewhere in between.

Even though only 100 of the 500 clusters identified so far have been surveyed, the team has been able to place a reasonably reliable preliminary upper limit on the mass of neutrinos — again, particles that had once been assumed to have no mass.

Previous tests have also assigned a lower limit to the mass of neutrinos, thus narrowing the anticipated mass of the subatomic particles to between 0.05 – 0.28 eV (electron volts). Once the SPT survey is completed, the team expects to have an even more confident result of the particles’ masses.

“With the full SPT data set we will be able to place extremely tight constraints on dark energy and possibly determine the mass of the neutrinos,” said Benson.

“We should be very close to the level of accuracy needed to detect the neutrino masses,” he noted later in an email to Universe Today.

SPT — The South Pole Telescope's unique position allows it to watch the night sky for months on end. (NSF)

Such precise measurements would not have been possible without the South Pole Telescope, which has the ability due to its unique location to observe a dark sky for very long periods of time. Antarctica also offers SPT a stable atmosphere, as well as very low levels of water vapor that might otherwise absorb faint millimeter-wavelength signals.

“The South Pole Telescope has proven to be a crown jewel of astrophysical research carried out by NSF in the Antarctic,” said Vladimir Papitashvili, Antarctic Astrophysics and Geospace Sciences program director at NSF’s Office of Polar Programs. “It has produced about two dozen peer-reviewed science publications since the telescope received its ‘first light’ on Feb. 17, 2007. SPT is a very focused, well-managed and amazing project.”

The team’s findings were presented by Bradford Benson at the American Physical Society meeting in Atlanta on April 1.