New findings that map the universe's cosmic growth support Einstein's
theory of gravity
Significant breakthrough in understanding the evolution of the universe


Date:
April 11, 2023
Source:
Princeton University
Summary:
Research by the Atacama Cosmology Telescope collaboration has
culminated in a groundbreaking new image that reveals the most
detailed map of dark matter distributed across a quarter of the
entire sky, reaching deep into the cosmos. Findings provide further
support to Einstein's theory of general relativity, which has been
the foundation of the standard model of cosmology for more than
a century, and offers new methods to demystify dark matter.


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FULL STORY ==========================================================================
For millennia, humans have been fascinated by the mysteries of the cosmos.


========================================================================== Unlike ancient philosophers imagining the universe's origins, modern cosmologists use quantitative tools to gain insights into the universe's evolution and structure. Modern cosmology dates back to the early 20th
century, with the development of Albert Einstein's theory of general relativity.

Now, researchers from the Atacama Cosmology Telescope (ACT) collaboration
have created a groundbreaking new image that reveals the most detailed
map of dark matter distributed across a quarter of the entire sky,
extending deep into the cosmos. What's more, it confirms Einstein's
theory of how massive structures grow and bend light, over the entire 14-billion-year life span of the universe.

"We have mapped the invisible dark matter across the sky to the largest distances, and clearly see features of this invisible world that
are hundreds of millions of light-years across, says Blake Sherwin,
professor of cosmology at the University of Cambridge, where he leads
a group of ACT researchers. "It looks just as our theories predict."
Despite making up 85% of the universe and influencing its evolution,
dark matter has been hard to detect because it doesn't interact with
light or other forms of electromagnetic radiation. As far as we know
dark matter only interacts with gravity.

To track it down, the more than 160 collaborators who have built and
gathered data from the National Science Foundation's Atacama Cosmology Telescope in the high Chilean Andes observe light emanating following
the dawn of the universe's formation, the Big Bang -- when the universe
was only 380,000 years old.

Cosmologists often refer to this diffuse light that fills our entire
universe as the "baby picture of the universe," but formally, it is
known as the cosmic microwave background radiation (CMB).

The team tracks how the gravitational pull of large, heavy structures
including dark matter warps the CMB on its 14-billion-year journey to us,
like how a magnifying glass bends light as it passes through its lens.

"We've made a new mass map using distortions of light left over
from the Big Bang," says Mathew Madhavacheril, assistant professor
in the Department of Physics and Astronomy at the University of
Pennsylvania. "Remarkably, it provides measurements that show that both
the 'lumpiness' of the universe, and the rate at which it is growing
after 14 billion years of evolution, are just what you'd expect from
our standard model of cosmology based on Einstein's theory of gravity."
Sherwin adds, "our results also provide new insights into an ongoing
debate some have called 'The Crisis in Cosmology,'"explaining that this
crisis stems from recent measurements that use a different background
light, one emitted from stars in galaxies rather than the CMB. These have produced results that suggest the dark matter was not lumpy enough under
the standard model of cosmology and led to concerns that the model may be broken. However, the team's latest results from ACT were able to precisely assess that the vast lumps seen in this image are the exact right size.

"When I first saw them, our measurements were in such good agreement
with the underlying theory that it took me a moment to process the
results," says Cambridge Ph.D. student Frank Qu, part of the research
team. "It will be interesting to see how this possible discrepancy between different measurements will be resolved." "The CMB lensing data rivals
more conventional surveys of the visible light from galaxies in their
ability to trace the sum of what is out there," says Suzanne Staggs,
director of ACT and Henry DeWolf Smyth Professor of Physics at Princeton University. "Together, the CMB lensing and the best optical surveys are clarifying the evolution of all the mass in the universe." "When we
proposed this experiment in 2003, we had no idea the full extent of
information that could be extracted from our telescope," says Mark Devlin,
the Reese Flower Professor of Astronomy at the University of Pennsylvania
and the deputy director of ACT. "We owe this to the cleverness of the theorists, the many people who built new instruments to make our telescope
more sensitive, and the new analysis techniques our team came up with."
ACT, which operated for 15 years, was decommissioned in September 2022.

Nevertheless, more papers presenting results from the final set of
observations are expected to be submitted soon, and the Simons Observatory
will conduct future observations at the same site, with a new telescope
slated to begin operations in 2024. This new instrument will be capable
of mapping the sky almost 10 times faster than ACT.

* RELATED_TOPICS
o Space_&_Time
# Cosmology # Big_Bang # Astrophysics # Astronomy #
Dark_Matter # Black_Holes # Space_Telescopes # Cosmic_Rays
* RELATED_TERMS
o Physical_cosmology o Dark_energy o Dark_matter
o Albert_Einstein o Ultimate_fate_of_the_universe o
Shape_of_the_Universe o Cosmic_microwave_background_radiation
o General_relativity

========================================================================== Story Source: Materials provided by Princeton_University. Original
written by Liz Fuller- Wright (Nathi Magubane from the University of Pennsylvania contributed to this story). Note: Content may be edited
for style and length.


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Link to news story: https://www.sciencedaily.com/releases/2023/04/230411105938.htm

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