Pennsylvania State University | 2020 Jul 29
Theory of loop quantum cosmology describes how tiny primordial features account for anomalies at the largest scales of the universe
While Einstein’s theory of general relativity can explain a large array of fascinating astrophysical and cosmological phenomena, some aspects of the properties of the universe at the largest-scales remain a mystery. A new study using loop quantum cosmology — a theory that uses quantum mechanics to extend gravitational physics beyond Einstein’s theory of general relativity — accounts for two major mysteries. While the differences in the theories occur at the tiniest of scales — much smaller than even a proton — they have consequences at the largest of accessible scales in the universe. The study ... also provides new predictions about the universe that future satellite missions could test.Tiny quantum fluctuations in the early universe explain two major mysteries about the
large-scale structure of the universe, in a cosmic tango of the very small and the very
large. A new study by researchers at Penn State used the theory of quantum loop
gravity to account for these mysteries, which Einstein's theory of general relativity
considers anomalous. Credit: Dani Zemba, Penn State
While a zoomed-out picture of the universe looks fairly uniform, it does have a large-scale structure, for example because galaxies and dark matter are not uniformly distributed throughout the universe. The origin of this structure has been traced back to the tiny inhomogeneities observed in the Cosmic Microwave Background (CMB) — radiation that was emitted when the universe was 380 thousand years young that we can still see today. But the CMB itself has three puzzling features that are considered anomalies because they are difficult to explain using known physics. ...
Research over the last three decades has greatly improved our understanding of the early universe, including how the inhomogeneities in the CMB were produced in the first place. These inhomogeneities are a result of inevitable quantum fluctuations in the early universe. During a highly accelerated phase of expansion at very early times — known as inflation — these primordial, miniscule fluctuations were stretched under gravity’s influence and seeded the observed inhomogeneities in the CMB. ...
Alleviating the Tension in the Cosmic Microwave Background Using Planck-Scale Physics ~ Abhay Ashtekar et al