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Cosmic tango between small and very large



Cosmic tango between small and very large

A small quantum shift in the early universe explains two major mysteries about the large-scale structure of the universe, in a small and very large cosmic tango. A new study by Penn State researchers used quantum line gravity theory to account for these mysteries, which Einstein’s theory of general relativity considers anomalous. Credit: Dani Zemba, Penn State

While Einstein’s theory of general relativity may explain a large range 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 quantum line cosmology ̵

1; a theory that uses quantum mechanics to extend gravitational physics beyond Einstein’s theory of general relativity – represents two major mysteries. While differences in theories occur at the smallest scales – much smaller than even a proton – they have consequences at the largest scales accessible in the universe. The study, which appears online on July 29 in the journal Physical Review Letters, also provides new predictions about the universe that future satellite missions may test.

While a painted picture of the universe looks fairly uniform, it has a large-scale structure, for example because galaxies and dark matter are not evenly 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 emerged when the universe was 380 thousand years old that we can still see today. But CMB itself has three confusing factors that are considered anomalies because they are difficult to explain using known physics.

“While seeing one of these anomalies may not be that statistically remarkable, seeing two or more together suggests that we live in an exceptional universe,” said Donghui Jeong, an associate professor of astronomy and astrophysics at Penn. State and author of the paper. “A recent study in the journal Nature Astronomy proposed an explanation for one of these anomalies that raised so many additional concerns, which are marked” a possible crisis in cosmology. “Using quantum line cosmology, however, we solved two of these anomalies naturally, by avoiding that potential crisis.”

Research over the past three decades has greatly improved our knowledge of the early universe, including how inhomogeneities in CMB were produced in the first place. These ingenuities are a result of inevitable quantum shifts in the early universe. During a very rapid expansion phase in very early times – known as inflation – these small primordial fluctuations are stretched under the influence of gravity and sow the inhomogeneities observed in the CMB.

Cosmic tango between small and very large

A diagram showing the evolution of the Universe according to the Loop Quantum Origins paradigm, developed by scientists at Penn State. Credit: Alan Stonebraker. P. Singh, Physics 5, 142 (2012); APS / A. Stone brake

“To understand how primordial seeds arose, we need a closer look at the early universe, where Einstein’s theory of General Relativity is shared,” said Abhay Ashtekar, Evan Pugh Professor of Physics, Chair holder of the Eberly Family in Physics, and director of the Penn State Institute for Gravitation and the Cosmos. “The standard inflation paradigm based on general relativity treats time space as a smooth continuum. Consider a shirt that looks like a two-dimensional surface, but on closer inspection you can see that it is woven from yarn. one-dimensional densely packed one way, the fabric of time space is really woven from quantum yarns.In the accounting of these yarns, the quantum cosmology of the line allows us to go to beyond the continuum described by General Relativity where Einstein’s physics breaks down – for example beyond the Big Bang. “

Researchers’ earlier investigation of the early universe replaced the idea of ​​the Big Bang, where the universe came out of nowhere, with the Big Bounce, where the current expanding universe emerged from a supercompressed mass that was created. when the universe contracted in its earlier phase. They found that all the large-scale structures of the universe accounted for by general relativity are explained in the same way by inflation after this Big Bounce using quantum loop cosmology equations.

In the new study, the researchers determined that inflation under loop quantum cosmology also solves two of the major anomalies that appear under general relativity.

“The primordial variations we’re talking about occur on the incredibly small Planck scale,” said Brajesh Gupt, a postdoctoral researcher at Penn State at the time of the research and currently at the University’s Texas Advanced Information Center. of Texas in Austin. “Planck’s length is about 20 orders of magnitude smaller than the proton radius. But the corrections to inflation on this hugely small scale simultaneously explain two of the anomalies on the largest scales in the universe. , in a very small and very large cosmic tango. “

The researchers also produced new predictions about a fundamental cosmological parameter and primordial gravitational waves that could be tested during future satellite missions, including LiteBird and Cosmic Origins Explorer, that will further improve our knowledge of the early universe.


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More information:
Abhay Ashtekar et al, Relieving Tension in the Cosmic Microwave Background using a Planck-Physical Scale, Physical Review Letters (2020). DOI: 10.1103 / PhysRevLett.125.051302

Provided by the University of Pennsylvania



Citation: Cosmic tango between small and very large (2020, 30 July) obtained on 30 July 2020 from https://phys.org/news/2020-07-cosmic-tango-small-large .html

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