According to two recent studies, a new, previously unknown form of dark energy may explain why the universe is expanding at an accelerating rate, contrary to theoretical predictions. Astrophysicists have discovered a new trace of dark energy that has existed for 300,000 years after the Big Bang, and cosmologists say it may be the mysterious matter that is forcing the universe to expand at an ever-accelerating rate.
But what is mysterious dark energy?
In the cosmological literature, dark energy is a hypothetical form of energy that fills the entire universe with an anti-gravitational effect, that is, it exerts negative pressure. It follows from Albert Einstein’s general theory of relativity, published in 1916, that the negative pressure of dark energy neutralizes gravity over long distances.
At present, this dark energy theory is the most plausible explanation for the fact, supported by astronomical observations, that the universe is expanding rapidly. It is estimated that 74% of Einstein’s (finite but infinite) world we know is mysterious dark energy, 22% dark matter (a type of matter that cannot be observed using astronomical instruments that does not emit any electromagnetic radiation) 3, 6 percent of the mass of The gas is interstellar, the remaining only 0.4 percent being the mass of stars and other celestial bodies.
According to one method, dark energy fills space equally, that is, it is considered a constant energy density, but in another interpretation it is a dynamic force field whose energy level can change in space and time. The so-called Lambda-CDM model, which combines these two approaches, also fits well with experimental astronomical observations.
It is noteworthy that the first evidence of dark energy comes from Hungarian astronomers, György Pal and colleagues,
Which deduced the existence of dark energy since 1992 from the redshift of radio and optical quasars.
In the late 1990s, other researchers came to the same conclusion by observing so-called Type Ia supernovae. In the early 2000s, additional sources such as gravitational lenses, cosmic microwave background radiation,
More accurate observations of supernovae have also confirmed that the universe is expanding at an accelerating rate.
This discovery won the 2011 Nobel Prize in Physics for three researchers, Samuel Perlmutter, Brian Schmidt, and Adam Reissette.
However, the presence of dark energy may explain not only the accelerating expansion of the universe, but also the problem of the so-called missing mass, that is, the problem of invisible matter that fills space.
The early dark energy simply absorbed by the universe
Two independent studies published last month on arXiv reported the detection of traces of early dark energy, based on processing observations made with the ATC (Atacama Cosmology Telescope) in Chile between 2013 and 2016. Although more observations are needed to confirm the discovery, the Advertising may still be a key milestone in understanding the acceleration process of the universe.
Because if the discovery turns out to be true, it could solve the age-old mystery that the state of the early universe is incompatible with the current rate of expansion of the universe.
The authors of the studies themselves note that this requires further observations, partly with the help of the ATC and partly with the help of the South Pole Telescope (SPT) in Antarctica, as they can test the results more accurately so far. Both instruments monitor the cosmic microwave background radiation,
What astrophysicists often call the “afterglow” of the big bang.
The cosmic microwave background radiation (CBM) is electromagnetic radiation that fills the entire universe, and was created about 300,000 years after the Big Bang, when nuclei and electrons fused into atoms.
One of the most dangerous evidence of the Big Bang is the microwave background radiation, the temperature of which is constantly dropping due to the expansion of the universe. By surveying the small changes in the cosmic microwave radiation that fills the entire universe, we also found evidence for a standard model of cosmology that traces the evolution of the universe into three main components; For dark energy, as before, also for mysterious dark matter as well as ordinary matter.
From the most accurate CBM map currently available, the European Space Agency map compiled between 2009 and 2013, the rate of expansion of the universe can be determined with complete accuracy. However, the results of more recent and more accurate measurements shocked scientists because the rate of expansion was five to ten percent higher than previously calculated.
To explain this phenomenon, Mark Kamionkowski, a researcher at Johns Hopkins University, was the first to propose the inclusion of early dark energy in the Standard Model. Kamionkowski and his colleagues say that early dark energy permeated the entire universe, but a few hundred thousand years after the Big Bang, it disappeared completely.
The Big Bang happened later than the current official time
The results of the two studies just published, which show traces of early dark energy, fit better with Kamionkowski’s theory than with the standard cosmological theory. This early dark energy could in no way be as powerful as current “ordinary” dark energy, but it could have contributed to the rapid cooling of the superheated plasma formed during the Big Bang.
Proving the existence of early dark energy may also improve our knowledge of the formation mechanism of the cosmic microwave background radiation. In addition, notes with ATC indicate that
that due to early dark energy, the Big Bang occurred 12.4 billion years later than the Standard Model 13.8 billion years ago.
Accordingly, the universe’s expansion rate is about five percent higher than the standard cosmological model, which also fits well with the most recent measurements.
The value of the discovery is greatly enhanced by the fact that in addition to the scientists who signed the publication, two other research groups reached the same conclusion from the ATC monitoring data set. Although the ATC polarization data suggest the presence of early dark energy, this needs to be supported even by observations made with other instruments. Therefore, as a next step, the researchers will compare their results with measurements from the Antarctic SPT to confirm the very important discovery of early dark matter.
A new type of dark energy could solve the mystery of the expansion of the universe Nature, Sep 17, 2021, Available here.
Bernadette Ball: They may have come across a new type of mysterious dark energy, Csillagászat.hu Csillagászati Hírportál, September 26, 2021.
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