Shock waves may have jolted the infant cosmos. Clumpiness in the density of the early universe piled up into traveling waves of abrupt density spikes, or shocks, like those that create a sonic boom, scientists say.
Although a subtle effect, the shock waves could help scientists explain how matter came to dominate antimatter in the universe. They also could reveal the origins of the magnetic fields that pervade the cosmos. One day, traces of these shocks, in the form of gravitational waves, may even be detectable.
Scientists believe that the early universe was lumpy — with some parts denser than others. These density ripples, known as perturbations, serve as the seeds of stars and galaxies. Now, scientists have added a new wrinkle to this picture. As the ripples rapidly evolved they became steeper, like waves swelling near the shore, until eventually creating shocks analogous to a breaking wave. As a shock passes through a region of the universe, the density changes abruptly, before settling back down to a more typical, slowly varying density. “Under the simplest and most conservative assumptions about the nature of the universe coming out of the Big Bang, these shocks would inevitably form,” says cosmologist Neil Turok of the Perimeter Institute for Theoretical Physics in Waterloo, Canada.
In a paper published September 21 in Physical Review Letters, Turok and Ue-Li Pen of the Canadian Institute for Theoretical Astrophysics in Toronto performed calculations and simulations that indicate shocks would form less than one ten-thousandth of a second after the Big Bang.
“It’s interesting that nobody’s actually noticed that before,” says cosmologist Kevork Abazajian of the University of California, Irvine. “It’s an important effect if it actually happened.”
上海品茶网LDV
These shocks, Turok and Pen found, could produce magnetic fields, potentially pointing to an answer to a cosmological puzzle. Magnetic fields permeate the Milky Way and other parts of the cosmos, but scientists don’t know whether they sprang up just after the birth of the universe or much later, after galaxies had formed. Shock waves could explain how fields might have formed early on. When two shocks collide, they create a swirling motion, sending electrically charged particles spiraling in a way that could generate magnetic fields.
Shocks could also play a role in explaining why the universe is made predominantly of matter. The Big Bang should have yielded equal amounts of matter and antimatter; how the cosmic scales were tipped in matter’s favor is still unexplained. Certain theorized processes could favor the production of matter, but it’s thought they could happen only if temperatures in the universe are uneven. Shocks would create abrupt temperature jumps that would allow such processes to occur.
Scientists may be able to verify these calculations by detecting the gravitational waves that would have been produced when shocks collided. Unfortunately, the gravitational ripples produced would likely be too small to detect with current technologies. But under certain theories, in which large density fluctuations create regions so dense that they would collapse into black holes, the gravitational waves from shocks would be detectable in the near future. “If there was anything peculiar in the early universe, you would actually be able to detect this with upcoming technology,” says Abazajian. “I think that is remarkable.”
相关文章Exclusive: Hong Kong mutual benefit policy serves to complement rather than compete with potential partners: HKSAR Chief Executive
Editors Note: Hong Kong Special Administrative Region (HKSAR) Chief Executive, John Lee Ka-chiu (Lee), led a high-level delegation of 70 people to participate in the third Belt and Road Forum for International Cooperation held in Beijing from October 18 to 19. At the forum, he invited entrepreneurs to Hong Kong to set up belt and […]
Growing fondness: why are Arab youth increasingly drawn to China?A recent public opinion survey conducted in Dubai targeting Arab youth revealed that eight out of 10 respondents consider China an ally, marking the highest number of respondents to hold this view in four years. According to data from the United Nations Population Fund, the Arab region is characterized by a substantial youth population, with […]
China’s medical assistance boosts healthcare development in South Pacific region"For this surgery, we have prepared for more than half a year," Xiao Yuehai told the Global Times when talking about the first laparoscopic surgery carried out in Solomon Islands. Xiao is an urologist from the Affiliated Hospital of Guizhou Medical University (AHGMU) and a member of the second group of Chinese medical workers dispatched […]
Shake down under
还没有评论,来说两句吧...