You and I are both stardust-astrophysics of busy people.

This week is the 1 1 holiday, and it is good to take advantage of the long vacation to travel, which shows that one is curious about the outside world. Even if you just keep walking, it shows that this person is curious about how many people will like his selfie in a strange environment. What do you want to gain when you travel, except for the vulgar taste of being praised on social platforms? At least you can study. The so-called long knowledge is actually to open up the pattern. For example, I lived in Chongqing for a long time and went to Mount Everest once before I knew what a mountain was. My mountain scale no longer stays in Jinyun Mountain. I have heard the word "Buddhist youth" for a long time. I didn't know what Buddhism was until I went to the White Horse Temple once. I am no longer a person who only knows Huayan Temple and Shaolin Temple.

But it's not enough to know this. When I climbed Mount Everest, it was the first time-taking a selfie, of course. What happened? Do you want to say "This mountain is really high, this mountain is really high"? No, I want to ask why Mount Everest can only be so high (because the gravity of the earth is not allowed to be higher, it will collapse if it is higher, and the gravity of Mars is not as good as that of the earth, so the highest mountain on Mars can reach 20 kilometers). For a globe with a diameter of1.3000 km, a mountain less than 10 km, like a grain of dust on billiards, does not affect our understanding of its smooth surface at all. When I came to Baima Temple, the first Buddhist temple in Middle-earth, I didn't exchange interests with the Buddha-kowtowing and burning incense in exchange for the blessing of the Buddha, but I thought from the history of Baima Temple why there have been frequent campaigns to destroy the Buddha in this land for more than 2,000 years (because the demolition of the temple made the treasury rich and the army soldiers).

These two examples are my understanding of the mode of communication-from the two dimensions of time and space. History can improve our understanding of the time dimension, and astronomy can improve our understanding of the time and space dimensions. In terms of time, every atom of you and me can be traced back to BIGBANG 65.438+0.33 billion years ago. In space, we are only in an ordinary corner of the universe (the periphery of virgo supercluster), in an ordinary galaxy (the Milky Way), in an ordinary area (the spiral arms of Orion), next to an ordinary star (the sun) ... Note that this is the universe, and whether there are multiple ones.

Of course, popular science astronomy is not to throw cold water on others when they are moved by great rivers and mountains and win the sense of knowledge superiority. Learning astronomy is precisely to know humility.

The Astrophysics of Busy People is a new work by Neil Degraces Tai Sen, a famous astrophysicist. He is more famous as a popular science expert, and he presided over a series of documentaries called Cosmos.

65.438+0.4 billion years ago (it was 65.438+0.4 billion years in the book, and now the accurate data should be 65.438+0.3 billion years), it is known that all the space, all the matter and all the energy in the universe are contained in a tiny scale, which is less than one trillion times the full stop of this sentence. That's a dense singularity.

First of all, gravity is gradually separated, and the other three natural forces are still unified. As time reaches -35 seconds of 10, the universe continues to expand, diluting all the concentrated energy. Just now, the unified forces split into "weak forces" and "strong nuclear forces". Later, the weak force split into electromagnetic force and "weak nuclear force", so all four forces that do not eat the structure of the universe appeared: the weak nuclear force that determines radioactive decay, the strong nuclear force that binds the nucleus and binds molecules.

In a very short time before, during and after the separation of strong nuclear force and weak electric power, the universe has become a boiling soup cauldron composed of quarks, leptons and their antimatter brothers, and bosons that bear their interaction. Strong theoretical evidence shows that in a period of time in the very early universe, when a certain force was separated, it gave the universe an unusual asymmetry, in which the number of matter particles was slightly higher than that of antimatter particles: the ratio was one billion to one billion.

Quarks began to form neutrons and hadrons, and the disturbing tiny "matter-antimatter asymmetry" mentioned above entered hadrons. Please pay attention to this almost negligible ratio. It is reasonable that a matter particle and an antimatter particle will annihilate. It is precisely because the material particles that come out every billion years constitute the material collections in the later universe, such as galaxies, stars, planets, roses, cows, you and me. ...

The scale of the universe has grown to several light-years (1 light-year, about 10 trillion kilometers), which is roughly equivalent to the distance from the sun to its nearest star. As the temperature of the universe continues to drop below 65.438+0 billion Kelvin, protons and protons, and of course neutrons, fuse to form a nucleus, hatching a baby universes, in which 90% of the nucleus is hydrogen, 654.38+00% is helium, and there are traces of deuterium (heavy hydrogen), tritium (overweight hydrogen) and lithium.

In this long time, the temperature of the universe is still high enough, and high-energy electrons can roam freely in photons, constantly absorbing and emitting photons, and interact like hitting a ball back and forth. However, when the temperature of the universe is below 3000 Kelvin (about half the surface temperature of the sun), this freedom comes to an abrupt end, and all the free electrons are combined with the nucleus. Their marriage left a ubiquitous visible light, which not only left a permanent mark on all the substances in the sky at that moment, but also announced that the initial formation process of cosmic particles and atoms had been completed.

The universe continues to expand and cool. At this time, due to gravity, matter gathers into clusters, forming what we call galaxies, the number of which is close to 654.38+000 billion. Each galaxy contains hundreds of billions of stars, and thermonuclear fusion takes place at the core of the stars. Those stars whose mass is dozens of times that of the sun have high enough pressure and temperature at their cores to make dozens of elements heavier than hydrogen. It is based on these elements that planets are formed and provide a place for the reproduction of life.

In an ordinary corner of the universe (outside virgo supercluster), an ordinary galaxy (the Milky Way) and an ordinary region (Orion's spiral arms), an ordinary star (the sun) was born. The gas cloud that forms the sun contains enough heavy elements to condense into a series of orbiting celestial bodies, including several rocky planets and gas planets, tens of thousands of asteroids and billions of comets. In the first few hundred million years, a large number of debris left in orbit were absorbed into larger celestial bodies. As there are fewer and fewer accretion substances in the solar system, the surface of the planet begins to get cold. A planet just from the sun gradually formed. If it is closer to the sun, the ocean will be evaporated; If it is farther away, the ocean will freeze. In either case, this planet will not give birth to life. This planet is the earth.

At this point, I'm afraid anyone can't help asking, what happened before the beginning of the universe? Why is there a BIGBANG? Who provided that source power? Tell you responsibly: I don't know. No one knows the world now. Whoever says who knows must be a fool.

Today, we only know that every atom in our body can be traced back to the Big Bang and nuclear fusion among massive stars that exploded more than 5 billion years ago.

We are the stardust of life, and then the universe gives us the mission of discovering ourselves-our journey has just begun.

65.438+300 million years ago, in the distant depths of the universe, black holes with the mass equivalent to 29 times and 36 times that of the sun merged into large black holes with the mass equivalent to 62 times that of the sun, and almost three times the mass of the remaining sun was all converted into energy-equivalent to a sudden increase of the power of 2 10 per sun.

At that time, the earth was still dominated by single-celled organisms. Those energy ripples spread in all directions, and complex life has evolved on the earth for 800 million years, including flowers, dinosaurs and flying creatures, as well as a vertebrate branch of mammals.

Until the last 10 thousand years, a primate branch of this branch had a genetic mutation, which promoted the production of language. From then on, this branch-Homo sapiens-will invent agriculture, civilization, philosophy, art and science. A scientist in the 20th century will invent the theory of relativity from his brain and predict the existence of that kind of energy gravitational wave.

After a whole century of prediction, this man traveled in the universe for 65.438+300 million years, and finally reached the earth, which was successfully captured by human science and technology. The prediction of a hundred years ago was finally confirmed. This macho man is Einstein.

And what is the basis of all this? It is the universal application of physical laws in the universe, and the periodic table of elements has clearly presented the matter of the universe. From this, we can draw some interesting insights: for example, if we meet an alien, it is definitely impossible for us to communicate in Chinese and English. If you want to shake hands with him, it may be interpreted as aggressive behavior, but if you say that the speed of light is constant and apply the law of gravity, we can continue our discussion. Another example is that alien creatures are carbon-based creatures like terrestrial creatures, because the carbon in the universe is most suitable for combining into stable macromolecules, and at the same time there are many, many.

Between the large spiral galaxies are dwarf galaxies and quasars. For example, the nearest galaxy in our galaxy is located 2 million light-years away, which is called Andromeda Nebula in history. To some extent, it is the bigger and brighter twin brother of the Milky Way. Magellanic Cloud is a dwarf galaxy around the Milky Way. In all the space regions that have been reliably investigated, the number of dwarf galaxies is much more than that of large galaxies, with the ratio exceeding 10 1. In the high-density environment of galaxy clusters, two or more large galaxies often collide, leaving a big mess.

The planet is relatively empty. If the solar system is compared to a sphere, then the volume occupied by the sun, all the planets and their satellites only accounts for a little more than one trillion of this sphere. But the space between planets is not empty, but contains various forms of big stones, pebbles, ice hockey, dust, charged particle streams, long-distance spacecraft and so on. Space is also full of great gravity and magnetic field. The speed of the earth in orbit is 30 kilometers per second, and it can sweep hundreds of tons of meteoroids every day-most of them are not as big as a grain of sand. When meteoroids rush into the atmosphere, their energy is huge, almost all of them vaporize when they touch, and then they burn up in the upper atmosphere of the earth. These fragile species on our planet rely on this atmospheric protective cover for survival and evolution. The moon may be the result of a wandering Mars-sized protoplanet colliding with the Earth at will.

Special mention should be made to Jupiter, which blocks the way of many comets with its strong gravitational field, otherwise they will wreak havoc in the inner solar system. Jupiter acts as the earth's gravitational shield, just like a big man, giving the earth long-term (hundreds of millions of years) relative peace and tranquility. Without Jupiter's protection, it would be difficult for life on earth to evolve into interesting and complicated life, and it would always live in the extinction crisis brought about by the devastating impact.

In fact, the strangest thing in the vacuum between galaxies (including them) is that it is a boiling ocean of virtual particles-a pair of undetectable matter and antimatter suddenly appear and disappear. This strange prediction of quantum physics is called "vacuum energy", which shows outward pressure, which is contrary to gravity and still flourishes without matter at all. The accelerating universe (the demonstration of dark energy ability) may be driven by this vacuum energy.

According to gravity, we know that the farther the distance, the smaller the gravity, so the orbital speed of the stars at the edge of each galaxy should decrease with the increase of distance, but the actual observation results are still very fast. Are Newton's Law and General Relativity Wrong?

There is nothing wrong with Newton's law and general relativity. If it is wrong, it will be miserable. The foundation of the whole physics collapsed, and the destructive power was unimaginable. In fact, there is some form of dark matter in the distant region of every spiral galaxy, beyond the visible edge. In the whole universe, on average, the gravity of dark matter is about six times that of all visible matter.

The effects of dark matter are real. We just don't know what dark matter is. Dark matter doesn't seem to interact with strong nuclear forces, so it can't form nuclei. It is not found that it interacts with weak nuclear forces, and even elusive neutrinos have weak interactions. It doesn't seem to interact with electromagnetic force, so it won't produce molecules or aggregate into dense dark matter balls. It neither absorbs nor emits light, nor reflects or scatters light. We knew from the beginning that dark matter does exert gravity and ordinary matter will react to it. But that's all. After so many years, we haven't found out what else it can do. Now, we can only be satisfied with treating dark matter as a strange and invisible friend and asking it to help us when the universe needs us to call it.

There is nothing wrong with Einstein's general theory of relativity, but Einstein also made mistakes, a big mistake, a big mistake that was somewhat wronged. At that time, I Buddha Einstein thought that the unstable static universe should have an "anti-gravity" relative to gravity, so I put forward a cosmological constant-λ, and wrote it into the equation of general relativity.

Later research found that the universe is not static, but expanding. Einstein then abandoned the cosmological constant and called it his biggest mistake. It wasn't long before everyone found out that Einstein's biggest mistake was to give up the cosmological constant. More and more evidence shows that the farther a galaxy is, the faster it retreats from the Milky Way. That is to say, "anti-gravity" not only exists, but also with the increase of vacuum, the density of matter and energy in the universe gradually decreases, and the relative influence of λ on the state of the universe becomes greater.

λ suddenly gets a physical reality, so it needs a name, so "dark energy" is at the center of the cosmic drama stage. This name very aptly reflects its mystery and our ignorance of its causes. The most accurate measurement results so far show that dark energy is the most important thing in the universe-it is the protagonist of the universe, accounting for 68% of all mass energy at present, dark matter accounts for 27%-supporting role, and ordinary matter only accounts for 5%-we are in this 5%.

With the accelerated expansion of the universe caused by dark energy, anything that is not bound by the Milky Way will degenerate faster and faster and become a part of the accelerated expansion of the space-time structure. The distant galaxies visible in the night sky today will eventually disappear out of sight, and they will leave us at a speed faster than the speed of light. About a trillion years later, everyone living in our galaxy may not even know the existence of other galaxies. Our Hubble volume will only include a neighboring long-lived star system. Beyond this starry night, there will be endless emptiness-that is, the dark side in deep space.

Dark energy is the basic attribute of the universe, which will eventually weaken the ability of future generations to understand the future universe.

There are few ways to find terrestrial planets in the book, and future interstellar immigrants depend on it.

1. Monitor the stars to see if they shake regularly. The periodic shaking of stars exposes the existence of planets around them. Contrary to what most people think, planets do not simply revolve around their main stars, but revolve around their same center of mass with their main stars. The bigger the planet, the greater the shaking amplitude of the star, so you can make predictions more easily when analyzing the spectrum of the star.

3. Chemical analysis of planetary atmosphere. Cosmic chemistry relies on spectroscopy-analyzing light through a spectrometer. If a planet is full of plants and animals, its atmosphere will be rich in biomarkers, that is, spectral evidence of life. Whether this mark comes from biology (part or all of life forms), human activities (Homo sapiens species in a broad sense) or technology (technology production), these evidences will be difficult to hide.

However, there are some defects in the above methods, and the evidence obtained by comprehensive verification will be more powerful. The first extrasolar planet was discovered in 1995, and now it has risen to 3000, most of which were found in a small area near the solar system in the Milky Way. Therefore, there should be many exoplanets. After all, our galaxy has10 billion stars, and the known universe contains hundreds of billions of galaxies. It is speculated that there are as many as 40 billion terrestrial planets in the Milky Way alone.

Some people say that astronomical research has aroused people's strongest sense of smallness and meaninglessness. The author disagrees with this view. On the contrary, he feels full of strength and passion. The human brain weighs only1400g, but the thinking activities it produces can help us find our place in the universe, which makes me feel very powerful. Many people actually misread nature. Out of an unreasonable arrogance, it first stems from the illusion of so-called meaning. On the other hand, the cultural assumption that "man is the spirit of all things and the essence of the universe" also contributes to this conceit.

Studying astronomy makes us realize that human beings are not masters of space and time, but as participants in a great cosmic existence chain, which has direct genetic connection with both existing and extinct species, and can be traced back to the earliest single-celled life on earth nearly 4 billion years ago.

Maybe you will think: we are smarter than bacteria. Yes, we are smarter than any creature that once ran, crawled or crawled on the earth. But how smart are we? We are much better than the smartest chimpanzees-but their genetic characteristics are very different from ours. It seems that a huge genetic gap separates us from our close relatives in the animal kingdom, so we can rightly praise our intelligence.

In fact, we are a whole with the rest of nature, and our position is neither higher nor lower than nature, but belongs to nature. A simple comparison of quantity, scale and scale can well eliminate people's conceit.

The number of water molecules in a 250 ml cup exceeds the number of water in all the oceans in the world. There are so many molecules in this glass of water that 1500 molecules can be distributed in every glass of water in the world. It is inevitable that some of the water you just drank once flowed through the kidneys of Confucius, Socrates, Genghis Khan and Joan of Arc.

The number of air molecules you inhale at a time is more than the air in the whole atmosphere of the earth calculated by the number of mouths, which means that you may have just inhaled the air molecules exhaled by Ying Zheng, Beethoven, Lincoln and Madame Curie.

There are more stars in the universe than any sand grains on the beach, and there are more seconds after the formation of the earth. Everyone who has lived has written more words and sounds.

If you want to see the panorama of the past, the perspective of the universe will take you there. It takes time for light to reach the earth from the depths of space, so the celestial bodies and phenomena you see are not what they are now, but what they were in the past, dating back to the beginning of time itself. In this predictable range, the panorama of the evolution of the universe is constantly unfolding.

Want to know what we are made of? The cosmic perspective once again provides an answer that surprises you more than you expected. All kinds of chemical elements in the universe are forged in the flames of massive stars, especially those that explode violently at the end of their lives, which enrich their galaxies. And the result? The four most common active elements in the universe, hydrogen, oxygen, carbon and nitrogen, are also the four most common elements in life on earth, and carbon is the basis of biochemistry.

We don't just live in this universe, the universe exists in our bodies.

For centuries, the discovery of the universe has devalued our view of ourselves again and again. The earth was once considered unique in astronomy until astronomers realized that the earth was just another planet orbiting the sun. Then we speculated that the sun was unique until we realized that countless stars in the night sky were actually the sun. Then we think that our galaxy, the Milky Way, is the whole known universe, until we are sure that countless vague celestial bodies in the sky are other galaxies, which are full of pictures of our known universe. Today, how easy it is to assume that there is only one universe. However, the emerging theory of modern cosmology and the constant reaffirmation that nothing unique can exist require us to continue to tolerate the latest influence on our unique expectations: the multiverse.

Cosmic perspective comes from basic knowledge. But it's not just about what you know, it's about having the wisdom and insight to use this knowledge to evaluate our position in the universe.

This is a famous photo. 1990, when Voyager 1 was about to fly out of the solar system, 6 billion kilometers away from the Earth, NASA ordered it to look back and took 60 photos. The light band in the photo is the sunlight reflected by the camera lens. One of them happens to include the earth, the bright spot in the picture.

Tai Sen's teacher, carl sagan, an astrophysicist and a famous science writer, was deeply impressed by this photo. He said a very famous sentence at a degree awarding ceremony in 1996:

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