Half the matter in the universe was missing – we found it hiding in the cosmos — The Conversation


Diligence, technological progress and a little luck have together solved a 20 year mystery of the cosmos.
CSIRO/Alex Cherney, CC BY-ND

J. Xavier Prochaska, University of California, Santa Cruz and Jean-Pierre Macquart, Curtin University

In the late 1990s, cosmologists made a prediction about how much ordinary matter there should be in the universe. About 5%, they estimated, should be regular stuff with the rest a mixture of dark matter and dark energy. But when cosmologists counted up everything they could see or measure at the time, they came up short. By a lot.

The sum of all the ordinary matter that cosmologists measured only added up to about half of the 5% what was supposed to be in the universe.

This is known as the “missing baryon problem” and for over 20 years, cosmologists like us looked hard for this matter without success.

It took the discovery of a new celestial phenomenon and entirely new telescope technology, but earlier this year, our team finally found the missing matter.

Origin of the problem

Baryon is a classification for types of particles – sort of an umbrella term – that encompasses protons and neutrons, the building blocks of all the ordinary matter in the universe. Everything on the periodic table and pretty much anything that you think of as “stuff” is made of baryons.

Since the late 1970s, cosmologists have suspected that dark matter – an as of yet unknown type of matter that must exist to explain the gravitational patterns in space – makes up most of the matter of the universe with the rest being baryonic matter, but they didn’t know the exact ratios. In 1997, three scientists from the University of California, San Diego, used the ratio of heavy hydrogen nuclei – hydrogen with an extra neutron – to normal hydrogen to estimate that baryons should make up about 5% of the mass-energy budget of the universe.

Yet while the ink was still drying on the publication, another trio of cosmologists raised a bright red flag. They reported that a direct measure of baryons in our present universe – determined through a census of stars, galaxies, and the gas within and around them – added up to only half of the predicted 5%.

This sparked the missing baryon problem. Provided the law of nature held that matter can be neither created nor destroyed, there were two possible explanations: Either the matter didn’t exist and the math was wrong, or, the matter was out there hiding somewhere.

Remnants of the conditions in the early universe, like cosmic microwave background radiation, gave scientists a precise measure of the unverse’s mass in baryons.
NASA

Unsuccessful search

Astronomers across the globe took up the search and the first clue came a year later from theoretical cosmologists. Their computer simulations predicted that the majority of the missing matter was hiding in a low-density, million-degree hot plasma that permeated the universe. This was termed the “warm-hot intergalactic medium” and nicknamed “the WHIM.” The WHIM, if it existed, would solve the missing baryon problem but at the time there was no way to confirm its existence.

In 2001, another piece of evidence in favor of the WHIM emerged. A second team confirmed the initial prediction of baryons making up 5% of the universe by looking at tiny temperature fluctuations in the universe’s cosmic microwave background – essentially the leftover radiation from the Big Bang. With two separate confirmations of this number, the math had to be right and the WHIM seemed to be the answer. Now cosmologists just had to find this invisible plasma.

Over the past 20 years, we and many other teams of cosmologists and astronomers have brought nearly all of the Earth’s greatest observatories to the hunt. There were some false alarms and tentative detections of warm-hot gas, but one of our teams eventually linked those to gas around galaxies. If the WHIM existed, it was too faint and diffuse to detect.

The red circle marks the exact spot that produced a fast radio burst in a galaxy billions of light-years away.
J. Xavier Prochaska (UC Santa Cruz), Jay Chittidi (Maria Mitchell Observatory) and Alexandra Mannings (UC Santa Cruz), CC BY-ND

An unexpected solution in fast radio bursts

In 2007, an entirely unanticipated opportunity appeared. Duncan Lorimer, an astronomer at the University of West Virginia, reported the serendipitous discovery of a cosmological phenomenon known as a fast radio burst (FRB). FRBs are extremely brief, highly energetic pulses of radio emissions. Cosmologists and astronomers still don’t know what creates them, but they seem to come from galaxies far, far away.

As these bursts of radiation traverse the universe and pass through gasses and the theorized WHIM, they undergo something called dispersion.

The initial mysterious cause of these FRBs lasts for less a thousandth of a second and all the wavelengths start out in a tight clump. If someone was lucky enough – or unlucky enough – to be near the spot where an FRB was produced, all the wavelengths would hit them simultaneously.

But when radio waves pass through matter, they are briefly slowed down. The longer the wavelength, the more a radio wave “feels” the matter. Think of it like wind resistance. A bigger car feels more wind resistance than a smaller car.

The “wind resistance” effect on radio waves is incredibly small, but space is big. By the time an FRB has traveled millions or billions of light-years to reach Earth, dispersion has slowed the longer wavelengths so much that they arrive nearly a second later than the shorter wavelengths.

Fast radio bursts originate from galaxies millions and billions of light-years away and that distance is one of the reasons we can use them to find the missing baryons.
ICRAR, CC BY-SA

Therein lay the potential of FRBs to weigh the universe’s baryons, an opportunity we recognized on the spot. By measuring the spread of different wavelengths within one FRB, we could calculate exactly how much matter – how many baryons – the radio waves passed through on their way to Earth.

At this point we were so close, but there was one final piece of information we needed. To precisely measure the baryon density, we needed to know where in the sky an FRB came from. If we knew the source galaxy, we would know how far the radio waves traveled. With that and the amount of dispersion they experienced, perhaps we could calculate how much matter they passed through on the way to Earth?

Unfortunately, the telescopes in 2007 weren’t good enough to pinpoint exactly which galaxy – and therefore how far away – an FRB came from.

We knew what information would allow us to solve the problem, now we just had to wait for technology to develop enough to give us that data.

Technical innovation

It was 11 years until we were able to place – or localize – our first FRB. In August 2018, our collaborative project called CRAFT began using the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope in the outback of Western Australia to look for FRBs. This new telescope – which is run by Australia’s national science agency, CSIRO – can watch huge portions of the sky, about 60 times the size of a full Moon, and it can simultaneously detect FRBs and pinpoint where in the sky they come from.

ASKAP captured its first FRB one month later. Once we knew the precise part of the sky the radio waves came from, we quickly used the Keck telescope in Hawaii to identify which galaxy the FRB came from and how far away that galaxy was. The first FRB we detected came from a galaxy named DES J214425.25–405400.81 that is about 4 billion light-years away from Earth, in case you were wondering.

The technology and technique worked. We had measured the dispersion from an FRB and knew where it came from. But we needed to catch a few more of them in order to attain a statistically significant count of the baryons. So we waited and hoped space would send us some more FRBs.

By mid-July 2019, we had detected five more events – enough to perform the first search for the missing matter. Using the dispersion measures of these six FRBs, we were able to make a rough calculation of how much matter the radio waves passed through before reaching earth.

We were overcome by both amazement and reassurance the moment we saw the data fall right on the curve predicted by the 5% estimate. We had detected the missing baryons in full, solving this cosmological riddle and putting to rest two decades of searching.

Sketch of the dispersion measure relation measured from FRBs (points) compared to the prediction from cosmology (black curve). The excellent correspondence confirms the detection of all the missing matter.
Hannah Bish (University of Washington), CC BY-ND

This result, however, is only the first step. We were able to estimate the amount of baryons, but with only six data points, we can’t yet build a comprehensive map of the missing baryons. We have proof the WHIM likely exists and have confirmed how much there is, but we don’t know exactly how it is distributed. It is believed to be part of a vast filamentary network of gas that connects galaxies termed “the cosmic web,” but with about 100 fast radio bursts cosmologists could start building an accurate map of this web.

This article was updated to indicate that Australia’s national science agency, CSIRO, operates the new telescope.

[Insight, in your inbox each day. You can get it with The Conversation’s email newsletter.]The Conversation

J. Xavier Prochaska, Professor of Astronomy & Astrophysics, University of California, Santa Cruz and Jean-Pierre Macquart, Associate Professor of Astrophysics, Curtin University

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

GDP measures the wrong things: Here’s something better — Marilyn Waring, TEDxChristchurch

“Because humankind and our planet need another way” — Marylyn Waring

In 1953, a group of economists got together to create the Gross Domestic Product: a way to measure everything that involves a market transaction. But GDP doesn’t measure the single biggest contributor to almost every nation’s economy—the unpaid labour performed every day in homes, in families, and by volunteers—and it doesn’t account for the cost of externalities like the environment. In this funny, engaging and enlightening talk, noted economist Dr Marilyn Waring makes a compelling and accessible argument for finding a better way to measure what counts.

Dr Marilyn Waring is a prominent New Zealand economist and feminist, and a leading activist for human rights.

At 23 years old, Marilyn was one of the youngest New Zealanders ever elected to Parliament. She pushed to have marital rape criminalised and threatened to cross the floor to vote with Labour on a nuclear-free New Zealand, precipitating the 1984 snap election.

On leaving Parliament, Marilyn earned a PhD in Political Economy; her research has been influential in establishing the field of feminist economics. She argues for the economic importance of women’s unpaid work and the environment, revealing the serious policy consequences caused by ignoring these when calculating national economic measures such as GDP.

More recently, Marilyn’s work has focused on the inequities of globalisation and the importance of acknowledging women’s work as an international human rights issue. She has undertaken a range of projects dealing with these issues for the United Nations. This talk was given at a TEDx event using the TED conference format but independently organized by a local community. Learn more at https://www.ted.com/tedx

#Runoff news: Blue River in Silverthorne closed due to high water — Summit Daily

Map of the Blue River drainage basin in Colorado, USA. Made using USGS data. By Shannon1 – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=69327693

From The Summit Daily (Deepan Dutta):

The Summit County Sheriff’s Office and town of Silverthorne have temporarily closed the Blue River from the base of the Dillon Dam to the Sixth Street Bridge in Silverthorne, according to a press release. The closure is due to high water caused by snow runoff being released from the dam.

Denver Water notified the town and Sheriff’s Office that water in the Upper Blue north of the Dillon Dam had reached 1,000 cubic feet per second on Monday, June 1. Sheriff Jaime FitzSimons and Silverthorne Police Chief John Minor agreed there was a risk of serious injury or even death presented by the high water.

The closure will remain in place until water levels are low enough that recreational boaters can safely pass under the Sixth Street Bridge.

@ColoradoStateU atmospheric scientists identify cleanest air on Earth in first-of-its-kind study

Aerosol filter samplers probe the air over the Southern Ocean on the Australian Marine National Facility’s R/V Investigator. Photo by Kathryn Moore via Colorado State University

Here’s the From Colorado State University (Jayme DeLoss):

Colorado State University Distinguished Professor Sonia Kreidenweis and her research group identified an atmospheric region unchanged by human-related activities in the first study to measure bioaerosol composition of the Southern Ocean south of 40 degrees south latitude. Kreidenweis’ group, based in the Department of Atmospheric Science, found the boundary layer air that feeds the lower clouds over the Southern Ocean to be pristine – free from particles, called aerosols, produced by anthropogenic activities or transported from distant lands. Their findings are published in Proceedings of the National Academy of Sciences.

Weather and climate are complex processes connecting each part of the world to every other region, and with climate changing rapidly as a result of human activity, it’s difficult to find any area or process on Earth untouched by people. Kreidenweis and her team suspected the air directly over the remote Southern Ocean that encircles Antarctica would be least affected by humans and dust from continents. They set out to discover what was in the air and where it came from.

“We were able to use the bacteria in the air over the Southern Ocean as a diagnostic tool to infer key properties of the lower atmosphere,” said research scientist Thomas Hill, coauthor on the study. “For example, that the aerosols controlling the properties of SO clouds are strongly linked to ocean biological processes, and that Antarctica appears to be isolated from southward dispersal of microorganisms and nutrient deposition from southern continents. Overall, it suggests that the SO is one of very few places on Earth that has been minimally affected by anthropogenic activities.”

CSU researcher Kathryn Moore collected bioaerosol samples aboard the R/V Investigator, an Australian Marine National Facility research vessel. Photo by Kendall Sherrin (CSIRO, AU) via Colorado State University

Samples were collected during the NSF-funded SOCRATES field campaign, led by research scientist and coauthor Paul DeMott. Graduate student Kathryn Moore sampled the air in the marine boundary layer, the lower part of the atmosphere that has direct contact with the ocean, aboard the Research Vessel Investigator as it steamed south from Tasmania to the Antarctic ice edge. Research scientist and first author Jun Uetake examined the composition of airborne microbes captured from the ship. The atmosphere is full of these microorganisms dispersed over hundreds to thousands of kilometers by wind.

Using DNA sequencing, source tracking and wind back trajectories, Uetake determined the microbes’ origins were marine, sourced from the ocean. Bacterial composition also was differentiated into broad latitudinal zones, suggesting aerosols from distant land masses and human activities, such as pollution or soil emissions driven by land use change, were not traveling south into Antarctic air.

These results counter all other studies from oceans in the subtropics and northern hemisphere, which found that most microbes came from upwind continents. Plants and soil are strong sources of particles that trigger freezing of supercooled cloud droplets, known as ice-nucleating particles. This process reduces cloud reflectivity and enhances precipitation, increasing the amount of sunlight reaching the surface and altering Earth’s radiative balance.

A wave breaks off the side of the Australian Marine National Facility research vessel, the R/V Investigator, during the SOCRATES field campaign. CSU researchers found sea spray emissions dominate cloud-forming material over the Southern Ocean. Photo by Peter Shanks (CSIRO, AU) via Colorado State University.

Over the Southern Ocean, sea spray emissions dominate the material available for forming liquid cloud droplets. Ice-nucleating particle concentrations, rare in seawater, are the lowest recorded anywhere on the planet.

The air over the Southern Ocean was so clean that there was very little DNA to work with. Hill attributed the quality of their results to Uetake and Moore’s clean lab process.

“Jun and Kathryn, at every stage, treated the samples as precious items, taking exceptional care and using the cleanest technique to prevent contamination from bacterial DNA in the lab and reagents,” Hill said.

Snow rapidly disappearing in #Colorado, sparking concerns about wildfire season — OutThereColorado.com #snowpack #runoff

From OutThereColorado.com (Breanna Sneeringer):

As the snowpack melts “faster than usual,” warmer and drier conditions have contributed to an increased risk of wildfires across parts of the state – despite statewide snowpack levels being reported “higher than normal” at the beginning of April. At that time, snowpack was at 102% of the norm statewide…

This increased lack of snowpack comes after a hopeful start to the year when it came to reducing drought risks…

The shrinking snowpack is concerning for wildfire season, especially in the southwestern corner of the state where several weeks of dry weather and early snowmelt have been observed. These conditions are similar to those…which resulted in several large wildfires including the West Fork Complex Fire and the 416 Fire.

USFS solicits comments on proposed #Aurora dam near Holy Cross — The Aurora Sentinel

A wetland area along Homestake Creek in an area that would be flooded by a potential Whitney Reservoir. The cities of Aurora and Colorado Springs are looking to develop additional water in Eagle County and divert it to the Front Range. Photo credit: Brent Gardner-Smith/Aspen Journalism

From The Aurora Sentinel (Grand Stringer):

The White River National Forest opened a public comment period last week concerning the next phase of a would-be reservoir project dubbed the Whitney Reservoir. Water authorities in Colorado Springs and Aurora plan to divert water near the Vail Valley — normally destined for the Colorado River — to the Front Range by way of pumps and tunnels.

Greg Baker, Aurora Water’s manager of public relations, said in November the Whitney Reservoir could eventually hold between 9,000 acre-feet and 19,000 acre-feet of water.

For comparison, Cherry Creek Reservoir stores more than 134,000 acre-feet.

Aurora Water and its southern counterpart, Colorado Springs Utilities, applied for a Special Use Permit to do so. Geologists would conduct ground-level seismic analyses of the ground below and also drill up to 150 feet below the surface. Currently, the operation proposes ten drilling sites.

The water could help Aurora meet the needs of a rapidly-expanding city while capturing water rights Aurora already holds, Baker said. He estimated the reservoir could be completed in 25 years if key steps were met, including a geological analysis.

The Whitney Reservoir project drew early attention from Colorado River conservationists and a fishing association concerned for the health of local fish habitats and the river system. Prolonged drought and existing diversions have already diminished Colorado River flows in recent decades.

The project could also impact pristine wetland ecosystems and would also require cutting near 500 acres from the Holy Cross Wilderness.

Members of the public can find more information about the project on the U.S. Forest Service website. Comments can be made any time but will be “most helpful” if submitted before June 30, 2020, the Forest Service said in an information release…

To comment on the project, or propose a different course of action, submit a comment online at https://cara.ecosystem-management.org/Public/CommentInput?Project=58221.

#Utah files change case to move #LakePowellPipeline point of diversion from #FlamingGorge to #LakePowell #ColoradoRiver #COriver #GreenRiver #aridification

Green River Basin

From The Salt Lake Tribune (Brian Maffly):

The water rights behind the proposed Lake Powell pipeline are not actually coming from the project’s namesake lake, but rather from the major reservoir upstream on the Green River.

Now, Utah water officials’ new request to overhaul those rights has handed opponents a fresh opportunity to thwart the proposed pipeline just as federal officials are about to release a long-awaited environmental review of the $1.2 billion project, which would funnel 82,000 acre-feet of water from Lake Powell to St. George.

The request, known as a change application, seeks to shift the the water rights’ “point of diversion” from Flaming Gorge Reservoir to a spot 400 miles downstream behind Glen Canyon Dam. The change, which also keys into where and how the water would be used, is needed to fit the goals of the pipeline, which is to bolster water supplies for Utah’s mushrooming Washington County.

The application was filed now because the timing made sense at this stage in the project’s development and has no bearing on whether the pipeline gets built, according to Joel Williams, assistant director of the Utah Division of Water Resources.

Environmental groups hope to block or at least delay the project’s approval if they can persuade Utah State Engineer Teresa Wilhelmsen to deny the change application filed April 13. Exhibit A in the many protests filed is the Colorado River system’s chronically diminishing flows in the face of climate change, long-term drought and overallocation…

A 1922 interstate compact divvies up water flowing in the Colorado River and its many tributaries among seven basin states and Mexico. For decades, Utah has underutilized its share, pegged at 23% of the Upper Basin’s flows above 7.5 million acre-feet, while the three Lower Basin states have historically drawn water in excess of their allocations, largely to fuel urban growth and corporate agriculture.

Secretary Babbitt’s river plan doesn’t go far enough — #Aspen Daily News #ColoradoRiver #COriver #aridification

San Luis People’s Ditch March 17, 2018. Photo credit: Greg Hobbs

Here’s an opinion piece from Denise Fort that’s running in The Aspen Daily News:

Each spring, the acequias in New Mexico carry cold, clear snowmelt to freshly furrowed fields on small farms. The centuries-old irrigation culture is recognized in state law and supported by strong communities.

These farms often come to mind when we think about agriculture in the West: a cool riparian valley with adjacent fields and people rooted in the land, growing crops that may be sold at a farmer’s market in a nearby town.

So when former Interior Secretary Bruce Babbitt suggested in a recent Writers on the Range opinion piece published in the Aspen Daily News on May 12, that a portion of agricultural water rights should be transferred to urban areas, it no doubt conjured up some strong emotions — small family farms drying up so that suburbanites could water their lawns and golf courses.

But Secretary Babbitt’s proposal makes sense, and he is right about the need to recognize the mismatch in population in the Colorado River Basin between the urbanized West and rural areas where most of the basin’s water is allocated. He is also right that the Colorado River cannot continue serving 40 million people, irrigating the same acreage, and meeting our aspirations for healthy rivers, in this time of megadrought.

There are a lot of caveats to his idea of people voluntarily retiring irrigation rights, including the need to create a process that allows full public participation. But unless we begin to retire irrigated acreage with a carefully managed strategy, we will have showdowns among states and tribes that share the basin’s water and increasingly desiccated rivers.

The real obstacle to Babbitt’s proposal springs from our romanticized vision of what agriculture looks like in the West. New Mexico may have acequia-fed fields, but it’s also in the nation’s top 10 for the number of dairy cattle, the products of which are largely exported to other states.

For every rain-fed cornfield sprouting emerald-like in the Arizona desert, there are tens of thousands of acres of alfalfa fields guzzling up millions of gallons of water per year. The United States is the world’s largest exporter of food, which means that the arid West is, in effect, exporting our water via huge, corporate farms.

Let’s not forget that it is agribusiness — not small farmers – that’s responsible for 80% of the water use in the West.

Meanwhile, climate change is drying up what water remains. The declining flows and warming temperatures are no longer just a contested forecast about the future, but our lived experience.

In my own corner of the West I’m astounded by how quickly desertification is occurring, with hard-packed soils where there was vegetation just a few years ago. Those obnoxious dust storms (haboobs) seem to be moving northward, leading me to tell everyone to watch Ken Burn’s powerful TV series on the Dust Bowl. Ranchers are on the front line in New Mexico, where grazing is looking more and more problematic.

Of course, water isn’t just valuable to farms and cities. The West has a huge outdoor recreation industry that depends on hiking, rafting and fishing, and our riparian areas grant solace in hectic times. Declining river flows, dried up springs and parsimonious releases for fishes detract from this sector of a growing economy.

Babbitt proposes to alleviate this situation by creating a mechanism by which farmers can lease their water rights to municipalities for a set period of time. He proposes free-market transactions — entirely voluntary and at the full discretion of each operator — funded by the federal government. I suggest that agricultural water also be made available to remain in our rivers for the health of our fragile river ecosystems.

Of course, there is a danger to a market-driven solution. If there were a federally run market in water rights, one would expect to see low-value agricultural areas to be the first to be approached for water sales.

That may be why in Europe policies explicitly protect small farms. This could lessen the departure of farmers from parts of northern New Mexico or rural areas on Colorado’s Western Slope, and other areas where small farms still exist.

No one is choosing the drought that has settled into the western United States, along with warming temperatures, wildfires and the rest of our changed climate. We have to cooperate to lessen the effect of climate on individuals and our shared environment.

That is why Bruce Babbitt’s proposal deserves a good, full-throated civic discussion. I just hope it is followed by actions to help the lands and people west of the 100th meridian thrive in the 21st century.

Denise Fort is a contributor to WritersontheRange.org, a nonprofit dedicated to spurring lively conversation about the West. She is a Professor Emerita at the University of New Mexico School of Law and chaired President Clinton’s Western Water Policy Review Advisory Commission.