The first time I heard that time is an illusion, I thought it was about Gautama Buddha, but I didn’t expect that this sentence was actually said by Einstein. Einstein wrote this sentence before he died. For those of us who believe in physics, the distinction between past, present, and future is just a stubborn and persistent illusion. This is so ruining our outlook. But if you think about it carefully, no one seems to be able to tell exactly what time is. Five minutes feels different from an hour. Is this feeling just time? Scientists use various physical formulas to describe objective events, and then tell us that events will not change because of your subjective feelings. But these physical formulas all have the parameter of time. If time is a feeling, doesn’t it mean that physical formulas are also based on feeling. After going around and around, I can only admit that time is an illusion. Although it sounds a bit ridiculous, it may actually be like this in reality.
Today, let’s talk about the story behind time. In 1986, scientists traveled deep into the Amazon jungle and discovered a tribe that had no time. This tribe is called Amundawa. Everyone in the tribe has no age, and there are no words to describe time or time periods such as year, month, day in the language. If we say that this happened last year, yesterday or the day after tomorrow, they will not be able to understand it. They only understand the four concepts of day and night, rainy season, and dry season, and they often change their names. For example, when your younger brother is born, you give your younger brother your name and you get a new name. This name represents the beginning of a new stage of your life.
If our ancestors had not invented a concept of time, we would be like the Amundawa people, only eating during the day, sleeping at night, giving birth to babies in the rainy season, and hunting in the sweat. Yesterday, now, tomorrow and next week, these imaginary words are also incomprehensible to us. There is another classic case, that is NBA star Uncle Mu. How old is he? This is definitely an eternal mystery. He comes from an African tribe that has no concept of age. When you were born, you would choose a tree and cut it with a knife, and then the tree would represent you. When you die, you might as well cut down this tree and expose the growth rings inside. These growth rings will be your epitaph, proving that you have been in this world and lived for so long.
When Uncle Mu left Africa, his tree had long since disappeared due to the war, so he never knew how old he was. When he participated in the draft in 1991, he was officially said to be 25 years old, but from the photos, he was obviously much older than the average person. Fans will all ask whether Guizhi let Uncle Mu play from his 20s to his 40s, or from his 40s to his 60s? It seems that humans are not born with an understanding of time. But we never noticed anything wrong with the time. Even a god-level scientist like Newton did not discover it. He also believed that time is absolute and a cosmic law that has been flowing at a constant speed. Only more than 100 years ago, the situation finally changed.
Back in 1902, a young man was introduced to the Swiss patent situation. At that time, there was an invention concept called synchronized time that was very popular. The young man can see dozens of imaginative inventions that synchronize time in one day. Some people use connecting rods, some are preparing to use radios, and some even want to open a watch shop dedicated to helping people tell the time. Employees were asked to hold a watch that told the time every morning, but the earliest trains traveled across Europe to carry the time. In fact, these inventions had only one purpose, which was to keep clocks across Europe at the same time.
Trains were already very developed at that time, but the time could never be synchronized. For example, when the train from Paris to Geneva was going, tickets were sold and departed according to Paris time along the way. When coming back, you had to follow the Paris time. When tickets are sold and trains depart at Geneva time, passengers are immediately confused and often run according to their own clocks, and the train has already left. These are all boys. If the dispatchers between cities do not agree on the time, a tragic train collision will occur. The young man worked with various time-related inventions every day, and he worked for three years. He suddenly realized that time is an illusion.
This day is May 23, 1905, and this young man is Einstein. On his way to work that day, he passed the clock tower in the city center.
Hearing the hourly bell, he suddenly thought, if he left this clock tower at the speed of light, how would the clock behind him keep time? Obviously, the light reflected by the clock also travels at the speed of light, so he cannot catch up with Einstein, so Einstein will always see the moment when he leaves the clock tower. But the watch on his hand continued to count, and his time did not stop. Thinking of this, Einstein immediately figured out a physics mystery. This mystery is called the constant speed of light. Originally, all speeds in physics can be changed. For example, if we stand on the ground and catch a bullet, our hand will be penetrated. If you stand on a high-speed plane and catch bullets, you might be able to catch him. This is because the bullet is flying and the plane is also flying. When the two speeds are the same, the bullet is stationary relative to the plane. According to common sense, the speed of light should be the same.
Once two scientists decided to use the earth to simulate the speed of light in an airplane and bullets to test this idea. We already know that the earth is rotating around the sun at high speed, and the speed of this rotation is about 30 kilometers per second. So when measuring the light hitting the earth head-on and the light chasing the earth from behind, the arrival time of them should be different. No matter how the results are measured, the arrival time is the same. After decades of measurement and countless experiments, the results have not changed. This is equivalent to measuring the speed of light while standing still, and then measuring the speed of light on a high-speed aircraft. The speed of light does not change. This is so weird, how to explain this phenomenon, until Einstein had an epiphany in front of the bell tower. He said that the constant speed of light we measure is actually because time is variable. The reason why they arrive at the same time is because the time of the light chasing the earth has expanded, and its one second has become longer. Time should be called space-time. When you move in space, you also move in time. For example, when you walk towards me, you feel that your time has not changed, but in my opinion, your time has slowed down, your voice has slowed down, and your movements have also slowed down. Until you stand still, our time is synchronized. You look at me and I look at you just as fast.
How to understand this counter-intuitive conclusion? This physicist named Brian Greene went on to tell such a story. According to Einstein's view of time and space, we get a blocky universe with out-of-control thinking in this universe model. Each cross section represents the three-dimensional space of the entire universe, and the next front is the future moment of this three-dimensional universe. The previous aspect is its past moment, just like a shutter. The present in our understanding may also be included in this moment. The clock in the office reached twelve o'clock, and the old cat jumped down from the window sill, 1,000 kilometers away. Pigeons outside flew up from the square, the moon 380,000 kilometers away was hit by a meteorite, a star exploded 100 light-years away, etc., etc., these events all happened simultaneously on one front, that is, a three-dimensional In the universe, all slices after this moment have already existed.
Like a projector, the universe continues to project. From the Big Bang 3.8 billion years ago to the formation of the Milky Way, to the birth of the Earth 4.5 billion years ago, the dinosaurs have become extinct until today. We are doomed in this blocky universe at every moment. The future, present and past are all just in front of us, there is no difference. And time flows past, disappears, and the future unfolds one by one. This is just our illusion. Going back to the past and seeing the future are scenarios that are easy to realize. You only need to move in space and time will move.
For example, there is an alien here in the universe, and there is another earthling on the earth 100 light-years away. Now they are both sitting still and their time is equal. So they're on the same slice. But if the alien gets on his bike and starts moving away from Earth, his movement will slow down the flow of time. At this time, their time is no longer the same. This also means that you are slicing the knife at an angle. Although it is only tilted a little, after being magnified to a spatial scale of 10 billion light-years, aliens will see hundreds of years of the past of this earthling. At this time, aliens will think that things are happening on the earth hundreds of years ago. Aliens will see the Earthlings when they were children, and will see slices of history in which Earthlings are landing on the moon, wars are breaking out, and so on. But when the aliens swung the car and started moving towards the earth, the slice tilted towards the future again. At this time, the aliens see the earth as it will look like hundreds of years from now.
In theory, these positive and oblique slices through time and space are reasonable, but in reality we only feel the present. We feel that the past time and space has disappeared, and the future time and space has not yet appeared. In fact, the past and the future are as real and existing as the present. Well, at this point in the story, it is no longer a question of whether time is an illusion, but that the entire universe is a piece of bread of destiny. The illusion of time and the destiny of the universe are just like the story told by Gautama Buddha. I really hope that Einstein is wrong. It is really difficult to accept this piece of bread of the fateful universe, but in reality Einstein seems to be right. Back in 1971, two physicists bought plane tickets for two atomic clocks. When the atomic clock was brought onto the aircraft, it was the most accurate clock at the time, and the error would not exceed one second for 20 million years. If Einstein's theory is correct, then after the two atomic clocks fly in circles in the sky, there will be a time difference with the atomic clocks on the ground. This time difference proves that the flight process slows down time. Sure enough, the two atomic clocks slowed down by 4/1 billion seconds after landing.
When the first-generation GPS satellites were launched into the sky, their positioning accuracy was only about 1,000 meters. But now the satellite is still the same satellite, and the principle is still the same. Why has the positioning progress been increased to one meter? In fact, the biggest factor affecting positioning is time. As long as the time is accurate enough, positioning will be infinitely accurate. The principle of satellite positioning is roughly this. There is a GPS chip in your mobile phone, which will release a section of electromagnetic waves. Electromagnetic waves are also a kind of light and travel at the speed of light. There is only one signal in this electromagnetic wave, which is his current time, and then a satellite in the sky received this signal.
The satellite also generates a message, which is the time when the satellite receives the signal. Subtracting the two times and dividing by the beam is the distance between the chip and the satellite. If the orbit of the satellite is known, the first position of the chip is also determined. At the same time, the second, third, and fourth satellites are also repeating this process, and the second, third, and fourth positions of the chip are also determined. When all positions are drawn and the circles intersect, the 100% accurate chip position is obtained. Theoretically, if there is an extremely accurate atomic clock in each satellite, and the chip is also timed by an extremely accurate atomic clock on the ground, then there will be no deviation, so where does the error come from? Sure enough, after scientists calibrated the GPS algorithm according to Einstein's space-time formula, the accuracy immediately increased from 1,000 meters to one meter.
In 2016, there were several energy-cold atomic clocks developed in China on board the Sky-2 experimental spacecraft. It is said that these cold atomic clocks are accurate to 13.8 billion years from the Big Bang to the present, with an error of no more than one second. This also means that China’s Beidou positioning system can be accurate to the millimeter level in the future. Maybe next year or the next year, even in a magical 3D city like Chongqing, the navigation system will be able to know which elevated level you are on, which is a bit scary just thinking about it. Einstein was indeed very powerful.
Einstein speculated that if there is a celestial body, its gravity is strong enough that even light will be sucked out by it and cannot escape. Then time is prohibited inside this celestial body. The closer the celestial body is to the outside, the slower time is. This celestial body is called a black hole. In 1915, Einstein predicted the appearance of a black hole through calculations, but no one has ever seen a black hole in reality, and the appearance of a black hole is only a theoretical prediction. When will humans be able to photograph a black hole?
Until 2019, humans took a photo of a black hole for the first time, and it was exactly as Einstein predicted. It seems that Einstein was right again. NSNA has two astronauts, Scott Carey and Mark Carey, who are identical twins and share the same gene. NSNA asked Scott to live in space for a year and Mark to stay on Earth, and then analyzed their genetic changes. Do you think Scott looks younger than Mark? Could this be the most intuitive manifestation of speed getting faster and time slowing down? Sure enough, after analyzing the two brothers' genes, they found that Scott's telomeres, which are structures at the ends of chromosomes, were significantly longer. Generally speaking, the older you are, the shorter your telomeres will be. But two days after returning to Earth, Scott's telomeres returned to normal length. Immediately afterwards, 93% of the genes in Scott's body returned to normal, but 7% of the genes were permanently mutated.
If Einstein was right, then there must be a projector that controls the universe to play forward irreversibly.
But we can’t find any clues about this projector from physical theory. The fact that the projector does not exist does this prove that Einstein was wrong? On the contrary, this further proves that Einstein was right, because the projector is most likely our brain and a mechanism in our subjective feelings. It is this mechanism that makes us feel like time is flowing and the universe is playing forward. In fact, the universe is not playing, everything is lying there quietly, there is no difference between past, present and future. The illusion of the brain makes us feel that time is flowing. Why is there such an illusion? If this illusion could be stopped in some way, wouldn't that be the so-called wisdom that transcends the past, present and future?
The story goes back to the very beginning. In March 1955, when Einstein wrote this, he was very sad because his good friend Besso had just passed away. It was Besso who introduced Hestein to work in the Patent Office. Einstein sent this letter to Besso's son, believing that time was an illusion and that Besso's death was destined. Just a month later, on April 18, Einstein also disappeared from the slice of the universe. But he told us that everything is doomed, and each of us died at the moment of the Big Bang thirty-eight years ago. In other words, each of us has not been born yet. Countless slices are there, time is just an illusion, the universe has already been determined. That’s all for sharing today’s story, thank you all.