There is a place in which we live, but it is the place where we least understand. We know much more about it now than we did hundreds of years ago, but it is still just the tip of the iceberg, and most of the theories about it are still speculations and cannot be confirmed.
This place is the universe.
When the ancients invented the word universe, they said that "universe" was the general term for space, "zeus" was the general term for time, and the word universe together was ancient and modern and up and down. It's all too accurate to summarize it in this term, because scientists now believe that the starry sky we see on Earth is actually a mixture of time and space. Why? Did the ancients already have a sense?
In addition, is there anything else beyond such a vast universe? How do we explore the world beyond the universe? Is there an end to the universe?
Today we're going to talk about the things in the universe. New friends may wish to click on the attention, we continue to read on.
<h1 class="pgc-h-arrow-right" Data-track="9" what is > universe? </h1>
Generally speaking stories, we have to start from the beginning. But the story of the universe is not ordinary, we are still not sure what the birth of the universe is like, we can only speculate from the current structure and shape of the universe, so we must first look at what the current universe is like.
The universe contains a wide variety of stars. The Earth we live on is the planet, and there are eight planets in the solar system, which are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune in order of distance from the Sun. Some friends should remember that it used to be said that there are nine planets in the solar system, and that was because Pluto, the farthest away from us, was kicked out of the planetary ranks by the International Astronomical Union and relegated to dwarf planets. Until now, the resolution has been controversial.
Planets move around stars, and moons move around planets. The stars and moons we are most familiar with are the sun and the moon.
The farthest star humans have ever reached is the Moon.
The Moon is about 384,400 kilometers from Earth. How far is this distance, let's find a reference. The circumference of the Earth's equator is 40,760 kilometers, and the distance around the Earth along the equator is already quite far, and the distance from the Earth to the Moon is 9.5 times that. Other stars are even more distant from us, and the vastness of the universe is visible.
The distance between the Earth and the Sun is 1.5 million kilometers. Our galaxy is centered on the Sun, which is the solar system we are most familiar with. Beyond the solar system is the Milky Way. The Milky Way is a cluster of stars made up of countless stars such as the Sun, and at present, the farthest universe we can observe is the Milky Way, but we have never broken through the solar system.
In 1977, the United States launched the Voyager 1 probe to explore Jupiter, Saturn, Uranus and Neptune. After completing the filming of Saturn, NASA said the Voyager 1 mission had turned into interstellar exploration, a trip to explore the boundaries of the solar system.
Forty-four years later, Voyager I is already 22.7 billion kilometers from Earth, but at its current speed, it is still 33 years before it breaks through the boundaries of the solar system. According to the analysis, Voyager One's energy will be depleted in 2025. I don't know if we will see the next generation of aircraft accomplish this goal in our lifetime.
Distances beyond the solar system can no longer be measured in kilometers, but in light years. A light-year is a unit of distance that refers to the distance traveled in a year by which light travels at a speed of about 300,000 kilometers per second. One light-year is roughly equal to 9.46 trillion kilometers, or 236.5 million times the circumference of the Earth's equator.
Why can't you use kilometers anymore? Let's hear about this distance. The other closest star to us is Proxima Centauri, which is 4.25 light-years away from the solar system. If we convert the above ratio into kilometers, we may finish reading this distance and our video will be over. The vastness of the universe is so indisputable.
Since it takes 4.22 years for light to travel from Proxima Centauri to Earth, by the time Proxima Centauri's light reaches Earth, 4.22 years have passed since we can't observe what happened on Proxima Centauri at the same time. This kind of "delay" abounds in the universe, when we see a star, maybe it has long been destroyed, we see only the light it emitted tens of thousands of years ago.
The travel time of light between stars and galaxies has been too long to be ignored. That's why scientists say that the starry sky we see on Earth is actually a mixture of time and space. The ancients' generalization of the "universe" seems even more subtle after a thousand years.
So, how big is the universe?
<h1 class="pgc-h-arrow-right" Data-track="48" > what the original state of the universe looked like? </h1>
Currently, the Planck satellite launched by humans can observe the universe in the range of 13.8 billion light-years. This also means that the history of the universe that we can observe is also 13.8 billion light years ago. But scientists don't dare to believe that the size of the universe is so big.
Because, before discussing the size of the universe, we have to determine what the shape of the universe is.
Ancient Chinese believed that the shape of the universe was a round place, while the West believed that humans lived in a hierarchical and orderly universe centered on the earth. Later, as we all know, Copernicus proved the heliocentric theory in the Middle Ages, which was the initial understanding of human beings about the true face of the solar system.
Newton, who laid the foundation of the modern physical system, proposed a broader model of the universe, arguing that the universe has always been in its current state, static and unchanging, so there is no problem of "birth". Centuries later, Einstein thought so too.
But the astronomical phenomena observed by astronomer Hubble in 1929 contradicted their theories. It turns out that the other galaxies we have observed have been moving away from Earth, which means that the universe is constantly expanding, which is the expansion of the universe.
Since the universe has been expanding outward, it is not difficult to speculate that the universe was not so vast a long time ago, and at the beginning, all the matter of the universe may have gathered into a point, and later in the "Big Bang" the current universe was born.
This is the now widely accepted Big Bang hypothesis. According to this hypothesis, the original appearance of the universe was a chaotic fireball with extremely high temperatures and extremely dense pressure and matter, and scientists called this form a "cosmic egg." This is very similar to the chaotic world of the legend of the ancient Chinese "Pangu Pioneering Earth". After the Big Bang, the universe expanded dramatically, forming a cloud of stars, and the interior of the cluster cloud further split, forming many stars, and the remaining material around the stars formed planets orbiting the stars.
Galaxies with only one star, such as the solar system, are called "single-star galaxies", and in fact, single-star galaxies are very rare, and most galaxies are binary or even three-star systems, as depicted in the novel "Three-Body".
There is also a special star cluster in the universe, called a globular cluster, composed of thousands of stars, and the number is so large that it can even reach a hundred thousand. These stars are usually very small in mass, meaning they emit dim light, but they can survive for a long time. According to speculation, the earliest stars in the universe were hidden in globular clusters. According to observations, the oldest stars have lived for more than 11 billion years, which also means that the age of the universe has exceeded 11 billion years. The solar system is still a very young member.
This is what the interior of the universe looks like now.
But what did the universe look like after the Big Bang? Our current level of observation is still very limited, like the frog in "Sitting in the Well and Watching the Sky" wants to figure out what the sky is like, so scientists can only continue to guess.
A cosmic model is shaped like a potato chip, seemingly an infinitely extended flat shape, but in fact the center is curved upwards and downwards at the same time, like small bubbles fried on potato chips. There is also a peculiar model of the universe that is shaped in a mysterious brittle angle, and the scientists who proposed this model believe that the Big Bang is incomplete, so that a certain direction of the universe has not been able to form a large range of space, and the other end is expanding infinitely, which has caused this mysterious brittle angle.
Both models may sound incredible, but both explain the origins of some of the difficult problems in the universe.
The model of the universe now supported by most scientists is spherical. The ball doesn't have to be a perfect spherical shape, it may be an irregular ellipse like earth. According to this theory, scientists speculate that "the universe is finite, but there is no end", which means that the universe is the same as the earth, although space is limited in external observation, but because of the spherical shape, we can never go to the end, and can always travel around the circumference indefinitely. The universe, unlike the surface of the Earth, is a three-dimensional space, so starting from any point in this sphere, no matter which direction we go from up, down, left, right, or back, we can't find the edges, but we can go back to the original starting point.
In addition, some scientists believe that the shape of the universe is a doughnut shape, Klein bottle and other strange shapes, and the current proposed model of the universe is various. What is the shape of the universe, I am afraid that it must be observed from the outside to be accurate.
That again involves the question, what is outside the universe?
<h1 class="pgc-h-arrow-right" Data-track="50" > is there an end to the universe? What is beyond the universe? </h1>
In fact, some scientists believe that there is no space-time outside the universe because the universe is constantly expanding. But there are also those who think that there is a higher level of outer universe beyond the universe, and that our universe is like a small cell, and that the outer universe is a more tightly organized organization. Maybe the intelligent creatures we've been looking for are in the outer universe. Other scientists believe that the universe is a multidimensional space, and there are many parallel universes outside this universe.
As mentioned earlier, at present, we can observe the scope of the universe is only 13.8 billion light-years, we can not even fully observe the Milky Way universe, space exploration has not yet flown out of the solar system, and human footprints have only reached the moon.
So, unfortunately, no matter what is outside the universe, according to the trend of human technology development, probably before the end of the solar system, we will not be able to explore.
But maybe one day there will be a sci-fi movie plot, and there will be alien life suddenly descending on Earth to share wisdom with us? Although we can now basically determine that there is no extraterrestrial life in the solar system, the universe is so vast that there may be space-time beyond the universe, and the possibility of extraterrestrial life is also very high.
Do you think there is any hope that humanity will be able to detect the true appearance of the universe? Leave a comment and let us know.
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