The Atacama Cosmology Telescope measures the oldest light in the universe, known as the cosmic microwave background. Using those measurements, scientists can calculate the universe’s age. Credit: Image courtesy of Debra Kellner
Atacama Cosmology Telescope findings suggest the universe is 13.8 billion years old.
From a mountain high in Chile’s Atacama Desert, astronomers with the National Science Foundation’s Atacama Cosmology Telescope have taken a fresh look at the oldest light in the universe. Their new observations, plus a bit of cosmic geometry, suggest that the universe is 13.77 billion years old, give or take 40 million years.
The new estimate matches the one provided by the standard model of the universe and measurements of the same light made by the Planck satellite, a space-based observatory that ran from 2009-2013.
This adds a fresh twist to an ongoing debate in the astrophysics community, said Simone Aiola, first author of one of two new papers on the findings posted July 15 to arXiv.org. The trouble is that research teams measuring the movements of galaxies have calculated that the universe is hundreds of millions of years younger than the Planck team predicted. That discrepancy suggested that a new model for the universe might be needed, and sparked concerns that one of the sets of measurements might be incorrect.
“Now we’ve come up with an answer where Planck and the Atacama Cosmology Telescope agree,” said Aiola, a researcher at the Flatiron Institute’s Center for Computational Astrophysics in New York City. “It speaks to the fact that these difficult measurements are reliable.”
A portion of a new picture of the oldest light in the universe taken by the Atacama Cosmology Telescope. This part covers a section of the sky 50 times the moon’s width, representing a region of space 20 billion light-years across. The light, emitted just 380,000 years after the Big Bang, varies in polarization (represented here by redder or bluer colors). Astrophysicists used the spacing between these variations to calculate a new estimate for the universe’s age. Credit: Image courtesy of ACT Collaboration
The age of the universe also reveals how fast the cosmos is expanding, a number called the Hubble constant. The Atacama measurements suggest a Hubble constant of 67.6 kilometers per second per megaparsec. This result agrees almost exactly with the previous estimate of 67.4 by the Planck satellite team, but it’s slower than the 74 inferred from the measurements of galaxies.
“Making this independent measurement is really exciting because there’s a mystery in the field, and this helps us sharpen our understanding of that mystery,” said Jeff McMahon, an associate professor of astronomy and astrophysics at the University of Chicago who led the design of the detectors and other new technologies used to make this measurement. “This confirms the ongoing discrepancy. And we still have much more data to analyze, so this is just the beginning.”
Assoc. Prof. Jeff McMahon
The close agreement between the Atacama Cosmology Telescope and Planck results and the standard cosmological model is bittersweet, Aiola said: “It’s good to know that our model right now is robust, but it would have been nice to see a hint of something new.” Still, the disagreement with the 2019 study of the motions of galaxies maintains the possibility that unknown physics may be at play, he said.
Like the Planck satellite and its earthbound cousin the South Pole Telescope, the Atacama Telescope peers at the afterglow of the Big Bang. This light, known as the cosmic microwave background, or CMB, marks a time 380,000 years after the universe’s birth, when protons and electrons joined to form the first atoms. Before that time, the cosmos was opaque to light.
If scientists can estimate how far light from the CMB traveled to reach Earth, they can calculate the universe’s age. That’s easier said than done, though. Judging cosmic distances from Earth is hard. So instead, scientists measure the angle in the sky between two distant objects, with Earth and the two objects forming a cosmic triangle. If scientists also know the physical separation between those objects, they can use high school geometry to estimate the distance of the objects from Earth.
Subtle variations in the CMB’s glow offer anchor points to form the other two vertices of the triangle. Those variations in temperature and polarization resulted from quantum fluctuations in the early universe that got amplified by the expanding universe into regions of varying density. (The denser patches would go on to form galaxy clusters.) Scientists have a strong enough understanding of the universe’s early years to know that these variations in the CMB should typically be spaced out every billion light-years for temperature and half that for polarization. (For scale, our Milky Way galaxy is about 200,000 light-years in diameter.)
The Atacama Cosmology Telescope measured the CMB fluctuations with unprecedented resolution and sky coverage, taking a closer look at the polarization of the light. “The Planck satellite measured the same light, but by measuring its polarization in higher fidelity, the new picture from Atacama reveals more of the oldest patterns we’ve ever seen,” said Suzanne Staggs, the telescope’s principal investigator and the Henry deWolf Smyth Professor of Physics at Princeton University.
This measurement was possible thanks to new technology designed and built by McMahon’s team. “Basically, we figured out how to make the detectors measure two colors and to pack as many into each camera as possible,” McMahon said. “Then we developed new lenses out of metamaterials.” (Metamaterials are a type of material that’s engineered to produce properties that don’t exist naturally.)
From conception to deployment at the telescope to analysis, the process has spanned nearly 10 years, McMahon said. “Working with this amazing team to develop this project all the way from concept sketches to producing results at the forefront of cosmology, has been absolutely fantastic.”
[embedded content] Prof. Wendy Freedman explains a new method for measuring the expansion of the universe.
Sara Simon, now at Fermi National Accelerator Laboratory, made significant contributions to detector design; UChicago graduate student Joey Golec developed methods to fabricate the metamaterial optics; and UChicago graduate student Maya Mallaby-Kay is now working to make the datasets public.
As the Atacama Cosmology Telescope continues making observations, astronomers will have an even clearer picture of the CMB and a more exact idea of how long ago the cosmos began. The team will also scour those observations for signs of physics that doesn’t fit the standard cosmological model. Such strange physics could resolve the disagreement between the predictions of the age and expansion rate of the universe arising from the measurements of the CMB and the motions of galaxies.
“We’re continuing to observe half the sky from Chile with our telescope,” said Mark Devlin, the telescope’s deputy director and the Reese W. Flower Professor of Astronomy and Astrophysics at the University of Pennsylvania. “As the precision of both techniques increases, the pressure to resolve the conflict will only grow.”
“I didn’t have a particular preference for any specific value — it was going to be interesting one way or another,” said Cornell University’s Steve Choi, first author of the other paper posted to arXiv.org. “We find an expansion rate that is right on the estimate by the Planck satellite team. This gives us more confidence in measurements of the universe’s oldest light.”
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References:
“The Atacama Cosmology Telescope: DR4 Maps and Cosmological Parameters” by Simone Aiola, et al., 14 July 2020, Astrophysics > Cosmology and Nongalactic Astrophysics. arXiv: 2007.07288
“The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectra at 98 and 150 GHz” by Steve K. Choi, et al., 14 July 2020, Astrophysics > Cosmology and Nongalactic Astrophysics. arXiv: 2007.07289
The ACT team is an international collaboration, with scientists from 41 institutions in seven countries. The telescope is supported by the National Science Foundation and contributions from member institutions.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
