"This means that the dark energy that causes the expansion of the universe may not be the vacuum energy of constant density, as many scientists believe, but rather a dynamical field of energy." Zhao Gongbo, a researcher at the National Observatory of the Chinese Academy of Sciences who led the study, said.
The international authoritative academic journal, nature and astronomy, recently published the Zhao Gongbo team's research on dark energy
If the dark energy is the vacuum energy, then the universe will continue to expand, and finally end with 'big tear'. But if dark energy is kinetic, then the universe may experience expansion, contraction, re expansion, and the emergence of a cyclic universe." Zhao Gongbo said.
Scientists use quasars to measure the universe. National Observatory of Chinese Academy of Sciences
Looking for the "yardstick"
The universe is so big, how do scientists measure it? Zhao Gongbo introduced that nature provides a magic ruler: baryon acoustic oscillations.
He explained that in the early universe, the baryonic matter, the photonic components like a as in a fluid state of high temperature and high density, the original creation of the universe behind disturbances propagated in this period of change caused by fluid, fluid density, temperature and pressure on the time sequence, the communication mechanism with mechanism the sound propagation is essentially the same as scientists, so called baryon acoustic oscillations.
About 380 thousand years after the big bang, the universe cooled from the "image" into a transparent, baryon acoustic oscillation propagation halted, oscillation information was "frozen" in time and space. But it has tremendous power that changes the distribution of matter in the universe, and ultimately drives galaxies to be distributed in a particular way.
In 2005, baryon acoustic oscillation signal was first discovered, astronomers finally won the coveted "ruler", it is used to measure the universe is flat or curved, how much is the rate of expansion.
But that's just the first step, and scientists need accurate measurements of the universe.
From 2012 onwards, the Zhao Gongbo team using the Apache Mountain Observatory in New Mexico Sloan telescope, from the observation data of galaxies and quasars, with high accuracy measured by the baryon acoustic oscillation signal.
The accuracy of baryon acoustic wave observation is getting higher and higher. Previous observations are concentrated in a very short period of time, and we use a new method, as do a CT scan of the more distant universe, can know more about the evolution of universe." Zhao Gongbo said.
On the basis of the "measuring ruler", astronomers will draw a three-dimensional map of the universe.
Baryon acoustic oscillations are provided by nature "ruler" Chinese National Observatory
Exploring dark energy
In 1929, Harbert, an American astronomer, found that the spectra of most galaxies were red shifted, indicating that these celestial bodies were moving away from us, which meant that the universe was in an expansion state. The discovery shocked the world and broke the idea that the universe was static for thousands of years.
At that time, people wanted the expansion of the universe to decelerate, so that the future of the universe may be static. But in 1998, two research teams led by American and Australian scientists found almost at the same time that the universe was speeding up in supernova observations.
Scientists have assumed an unknown mysterious force that speeds up the expansion of the universe, called dark energy. At present, scientists know little about the nature of dark energy. Scientists put forward a variety of theoretical models of dark energy, such as the dark energy model proposed by Zhang Xinmin, a researcher at the Institute of high energy physics, Chinese Academy of sciences. At the moment, the Zhao Gongbo team's observations with the Sloan telescope coincide with Zhang Xinmin's dark energy model.
To test many theoretical predictions, large-scale numerical simulations are often needed. "We use China's Tianhe computer, and some foreign supercomputers, to simulate about 2000 universes for data analysis." Zhao Gongbo said.
Sloan telescope. National Observatory of Chinese Academy of Sciences
On the computer of scientists, billions, billions of years have passed by, galaxies have formed, and the universe has evolved.
"I want to know why the universe is speeding up There are too many new physics here. Ordinary materials account for only 5% of the universe, and 95% of the dark matter and dark energy are what we don't know. Once one day, we know what dark energy is, and it will bring about a revolution in physics as a whole." Zhao Gongbo said.
According to reports, the next 5 to 10 years, and Chinese international will run a large number of ground and space dark energy projects, for example, China future space station will include an optical module, it is a two meter diameter space telescope, dark energy will be the main target of science.