In the new study, scientists at the University of British Columbia suggested that the universe is expanding due to the fluctuations of space and time. At the moment around the mysterious dark energy has crowded a lot of confused theories. New research could lead to better understanding of dark energy. Since the end 1920-x of years, astronomers knew that the universe is in a state of expansion. Initially predicted by the General theory of relativity, this paradigm has led to the most wide adopted cosmological model — the Big Bang theory. However, in the 90-ies the situation has become somewhat confusing, because the latest observations showed that the universe is expanding with ever increasing speed.
All this has led to the emergence of the theory of dark energy, the mysterious invisible force that is pushing the expansion of space. Like dark matter, which explain the “missing mass” of dark energy has become the Holy Grail of scientists who tried to explain to her find, or at least to create an adequate theoretical framework for it. A new study by the University of British Columbia suggests that the expansion of the Universe may be associated with fluctuations in space and time.
The study, recently published in the journal Physical Review D, was conducted under the leadership of Cindy Wong, a graduate student in the Department of physics and astronomy at UBC. Under the guidance of Professor William Unruh (the one who suggested the Unruh effect) and with the help of Zhen Zhu (another UBC graduate student), they threw a dark energy a new look.
The team began with a review of the inconsistencies arising from two main theories that together explain all natural phenomena in the Universe. These theories — not that other as the General theory of relativity and quantum mechanics explain how the universe behaves on the largest scales (stars, galaxies, clusters) and the smallest (subatomic particles).
Unfortunately, these two theories are incompatible when it comes to small question, known as gravity. Scientists are still trying to explain it from the point of view of quantum mechanics. The existence of dark energy and the expansion of the Universe — another point of disagreement. First, candidate of the theory like the vacuum energy, which represent the most popular explanations for dark energy, have serious inconsistencies.
According to quantum mechanics, the vacuum energy must have a higher energy density. But if so, then from the General theory of relativity implies that this energy must have incredibly strong gravitational effect, which would be sufficient to the universe exploded in size.
“The problem — says Professor Unruh — that any naive calculation of the vacuum energy gives a huge value. If we assume that there is some limit to the energy density does not exceed much the Planck energy density (about 1095 j/m3), then we can determine the Hubble constant — the time period in which the universe roughly doubles in size — as 10-44 seconds. It turns out, the typical approach is to assume some reduction of this value to the real rate of expansion of 10 billion years. But this “some” is quite mysterious and nobody has offered even half of a convincing mechanism.”
While other scientists have tried to modify the General theory of relativity and quantum mechanics to resolve these inconsistencies, Wong and his colleagues sought a different path.
“Previous research or tried to modify quantum mechanics to make the vacuum energy less, or to modify General relativity so that gravity would balance the energy of the vacuum. But quantum mechanics and General relativity are two of the most successful theories describing the Universe. Instead of trying to modify quantum mechanics or General relativity, we believe that you first need to understand them better. We take seriously the greatest density of vacuum energy predicted by quantum mechanics, and just made it in OTO, not modifying anything”.
Within their study, Wong and his colleagues have made new calculations of the vacuum energy, considering the high predicted energy density. Then considered the possibility that on the smallest scale — billions of times smaller than electrons — the fabric of space-time is subject to wild fluctuations, oscillating at each point between expansion and contraction.
As rocking back and forth, these vibrations lead to the fact that the universe is expanding, slowly but with increasing speed. After performing their calculations, they noted that this explanation is consistent with the presence of the quantum vacuum energy density, and with General relativity. In addition, it is consistent with what scientists have observed for almost a century.
“Our calculations showed that the universe at the smallest scales really expands and contracts with absurdly high speed. But on a large scale due to the averaging of small scale physics do not notice this “quantum foam”. It has a short residual effect in the creation of the cosmological constant (dark energy effect). In a way it’s like waves in the ocean, which move like the ocean, perfectly smooth, but in fact we know that under this apparent simplicity hides a mad dance of atoms in the water, and waves average these fluctuations, so the surface is smooth”.
In contrast to the conflicting theories of the Universe, in which various forces that control it, can’t live in the world and should cancel one another in the film Wong and his colleagues, the universe is constantly moving. The effects of the vacuum energy vzaimozachet, with the resulting expansion and acceleration, we see it all the time.
Although it is too early to tell, this image is highly dynamic Universe (even in the smallest scale) could transform our understanding of space-time. At least these theoretical insights be sure to stimulate debate in the scientific community, as well as experiments that will need to offer direct evidence. And this, as far as we know, the only way to understand the Universe, step by step.
Fluctuations of space and time: the proposed new explanation of dark energy
Ilya Hel