From a philosophical point of view, people think that the universe has no beginning, no end and no end. However, we are not going to discuss this abstruse concept in depth, so let's leave it to philosophers to study. We might as well squint and use our existing science and technology to talk about the universe that we can understand and observe. People call it "our universe" or "total galaxy".
According to the latest observation data, the farthest galaxy observed by people is 65.438+0.3 billion light years. In other words, if a beam of light is emitted from this galaxy at a speed of 300,000 kilometers per second, it will take 654.38+03 billion years to reach the earth. This distance of 654.38+0.3 billion light years is the universe as we know it today. More specifically, the universe as we know it today. It is a spherical space with the earth as the center and the distance of 65.438+0.3 billion light years as the radius. Of course, the earth is not really the center of the universe, and the universe is not necessarily a sphere. It is only limited by our current observation ability that we can only understand this extent.
In this spherical space with a radius of1300 million light years, there are about1250 million galaxies that have been discovered and observed, and each galaxy has hundreds to trillions of sun-like stars. So, as long as you do a simple math problem, you can easily understand how many stars we have observed in the universe. In such a vast universe, the earth is really a drop in the ocean.
All along,
Astronomers like us want to know how big the universe is.
Recently, the American Space Network reported that after hard calculation, astronomers found that the universe is extremely huge, with a length of at least 65.438+056 billion light years.
"Such a discovery about the size of the universe is obviously based on the premise that the universe is spherical and infinite," Daming Chen, a researcher at the National Astronomical Observatory of China, said in an exclusive interview with reporters. "For a long time, there has been such a debate in the field of cosmology, whether the universe is spherical, saddle-shaped or flat."
Zhang Yue, an associate professor at Beijing Normal University, said: "The international mainstream cosmology generally believes that the universe is flat and infinite."
So, where does the debate around the universe come from? What makes sense?
The most common view is that after the Big Bang, the universe was born.
"According to the most influential Big Bang theory in modern cosmology, our universe was created by a very small point explosion about 654.38+037 billion years ago, and the universe is still expanding," said researcher Daming Chen. "This theory has been confirmed by a large number of astronomical observations."
According to this theory, in the early universe, the temperature was very high. With the expansion of the universe, the temperature began to drop, producing neutrons, protons and electrons.
Since then, these elementary particles have formed various elements. These particles attract and fuse with each other, forming larger and larger clumps, and gradually evolving into galaxies, stars and planets. Life phenomena have appeared on individual celestial bodies, and finally human beings who can understand the universe have been born.
Is the universe spherical and finite?
"The idea that the universe is spherical has existed for a long time, although it is not the mainstream of international cosmology," Daming Chen said. "Every time it is mentioned, it will attract people's attention because it is very strange."
One of the most obvious examples is the universe model established by American mathematician Jeffrey Wilkes not long ago: a mirror maze of limited size, shaped like a football.
The model of "shaped like a football" shocked the scientific community, because this theory claimed that the universe created an "illusion" without boundaries, because this limited space reflected itself endlessly through the "turning" effect.
Wilkes believes that people think that the universe is infinite because the universe is like a mirror maze, and light passes through it again and again, giving people the illusion that the universe is infinitely extended. This amazing inference was later included in New Scientist magazine and widely circulated among the people as a kind of "fantastic talk".
Just recently, similar amazing news came from the American space network. A writer interviewed a famous astrophysicist in this country and learned that the length of the universe is 65.438+05.6 billion light years.
In this new study, researchers examined the primary radiation left in the vast universe after the Big Bang. They came to the conclusion that there may be some magical cosmic "mirror room" in the universe, so that an object can be seen in two places.
Because of this conclusion, they became supporters of spherical cosmology.
The length is156 billion light years? Why is the size of the universe a number you have never heard of?
Their explanation is this: the age of the universe is about 65.438+037 billion years. It takes more than 654.38+0.3 billion years for light to reach our earth from the earliest known galaxy. So we can assume that the radius of the universe is 65.438+037 billion light years, so the length of the whole universe is twice that of the universe, which is 27.4 billion light years. However, it has been expanding since its birth, and theorists believe that the universe originated from.
Professor Neil Cornish, an astrophysicist at Montana State University, explained: "The distance of light propagation in the early universe increased with the expansion of the universe, just like compound interest in a bank." He proposed that it is conceivable that only 6.5438+0 million years after the birth of the universe. Light travels for one year, and the distance traveled is 654.38+0 light years. He said: "At that time, the size of the universe was about 654.38 smaller than it is now. Therefore, 1 light-year is extended to 1000 light-year. " All the distances add up to 78 billion light years. He said that light has not gone that far, "but the starting point of photons that have reached our earth through137 billion years is now 78 billion light years away. This is the radius of the universe, so the diameter is156 billion light years. This is just based on.
Scientists have studied the cosmic microwave background radiation (CMB) formed 380,000 years after BIGBANG. At this time, the universe fully expands and cools to form atomic matter. The difference of radiation temperature in different directions in the sky can be used to remind the age of the universe and constrain many important cosmological parameters. Cosmic microwave background radiation is an image of the universe in its infancy. At this time, no stars have formed. The American Journal of Physical Review published this new research work on May 2, 20041. Its key point is to use the cosmic microwave background radiation data to find the phenomenon of the universe in pairs. Accordingly, multiple images of the same object in the universe can be presented in different places in time and space. The mirror room effect may mean that the universe is finite, but it produces the feeling that the universe is infinite. He told reporters
The debate about the structure of the universe, is the universe spherical, saddle-shaped or flat?
Regarding the structure and future of the universe, modern cosmology believes that if the total mass of the universe is greater than a certain critical mass, then the structure of the universe is spherical and will shrink one day under the action of gravity.
If the total mass of the universe is less than the critical mass, then the structure of the universe is saddle-shaped, and the gravity inside the universe cannot offset the expansion speed of the universe, which makes the universe expand continuously.
If the total mass of the universe is exactly equal to the critical mass, then the structure of the universe is flat and the universe will continue to expand as it is now.
The structure of the universe is actually the structure of time and space, which is hard for ordinary people to imagine. However, scientists have put forward a standard to measure the structure of the universe: if two parallel beams are getting closer, then the structure of the universe is spherical; If two parallel beams are farther and farther away, then the structure of the universe is saddle-shaped; If two parallel beams are always parallel, then the structure of the universe is flat. The structure of the flat universe can be explained by Euclidean geometry.
Several evidences of flat cosmology.
The conclusion that the structure of the universe is flat was drawn by multinational scientists who participated in the "Extragalactic Millimeter Wave Radiation and Geophysical Balloon Observation Project". The purpose of this project is to study the details of cosmic background radiation.
At the end of 1998, scientists placed some radio telescopes on the top of the helium balloon. As the helium balloon rose to a height of about 40 kilometers above the ground, they observed the specific universe there 1 1 day, and obtained the most detailed data about the early radiation of the universe so far.
After research, scientists found that the first beam of light emitted by the universe did not bend on a large scale, which means that the first two parallel beams have always been parallel, which means that the structure of the universe is flat, which means that the total mass of the universe is just equal to the critical mass, and the universe will continue to expand as it is now.
As early as 1965, scientists have detected cosmic background radiation evenly distributed in space, and its temperature is MINUS 270 degrees Celsius. According to the big bang theory, this kind of radiation is the "ember" after the big bang. From these "embers", scientists can speculate on the early scene of the Big Bang.
199 1 year, the American cosmic background detection satellite found that there were tiny temperature fluctuations in the cosmic background radiation, just like the faint "fire" flashing in the "embers", which indicated that there was already a very low-density material cloud in the universe at that time. It was these clouds that gradually contracted to form later galaxies. The "Extragalactic Millimeter Wave Radiation and Geophysical Balloon Observation Project" is based on the discovery of this satellite.
In addition, observation instruments such as Hubble telescope and gamma-ray detector, which were launched in April of 1990 and April of199/kloc-0, respectively, have also observed the structure and evolution of the universe and achieved a lot of results. These results agree that the universe will continue to expand.
The observation and research on the birth and evolution of the universe has just started, and the speculation on the structure and future of the universe is only a preliminary conclusion. In the next few years, scientists plan to launch two satellites to observe the early radiation of the universe more accurately. In addition, scientists will take other means to observe the universe, and the mystery of the birth and structure of the universe will be further revealed.
Modern cosmology in past dynasties
In the 7th century, Newton pioneered the way of studying cosmology by mechanical methods and established classical cosmology. In 2007, Einstein established a cosmological model of "static, finite and unbounded" on the basis of general relativity, and introduced cosmological principles, curved space-time and other concepts. Thus, the era of modern cosmology research was opened. 1922, the Soviet mathematician Friedman discussed the possibility of the non-static universe and the expansion of the universe. 1927, Belgian bishop and astronomer Lemaistre proposed a cosmological model of uniform isotropic expansion. 1932, Lemaistre put forward the concept that "primitive atoms" exploded to form the universe. From 6548 to 0948, American astronomer Gamov developed Lemaistre Thought.