This paradox is based on Einstein's general theory of relativity. General relativity holds that our universes are parallel and connected, and we can go back to the past through holes. According to the assumption, if it is established in the past, it will inevitably produce the above paradox. In Einstein's special theory of relativity, we are told that time and space are interrelated. Because the speed of light is constant, all movements, even time itself, must correspond to it, so time is relative. Therefore, in order to explain the above paradox, people put forward the concept of "parallel universe", which is Hawking's "parallel space theory".
Is the other article you are reading exactly the same as this one? That guy is not himself, but lives in a misty mountain range, endless fields and noisy city, and revolves around a star and seven other planets, and is also called "the earth"? His (her) life experience is the same as yours every second. However, maybe at the moment she is about to put down this article and you are going to read it.
This idea of being in two places at the same time sounds strange and unbelievable, but it seems that we have to accept it because it is supported by various astronomical observations. At present, the most popular and simplest model of the universe points out that there is a galaxy exactly like our Milky Way at a distance of about 10 (10 28) meters, and there is one exactly like you in it. Although this distance is beyond people's imagination, it does not affect the authenticity of your "doppelganger". The idea originally originated from a very simple "natural possibility" rather than the assumption of modern physics: the size of the universe is infinite (or at least large enough), and as astronomical observations have pointed out, matter is evenly distributed. In this case, according to the statistical law, it can be concluded that all events (no matter how similar or identical) will happen countless times: there will be countless planets that will give birth to human beings, among which there will be people exactly like you-with the same looks, names, memories and even the same actions and choices as you-and there will be more than one such person, to be exact, infinite.
The latest cosmological observation shows that the concept of parallel universe is not a metaphor. Space seems to be infinite. If so, all possible things will happen, no matter how absurd. In addition to our astronomical observation ability, there is a universe exactly like ours. Astronomers even calculated their average distance from the earth.
You may never see your own "shadows", but science tells us that they exist. The farthest distance that you can observe is the farthest distance that light has traveled since BIGBANG: about 654.38+0.4 billion light years, which is 4x10.26 meters-which defines the size of our observable horizon, or simply, the size of the universe, also called Hubble volume. Similarly, the other universe you live in is also a sphere of the same size. The above is the most intuitive explanation of "parallel universe". Every universe is a small part of a larger "multiverse".
The words of Solomon in the Bible:
Ecclesiastes 1: 9 What has happened will happen again. What has been done will be done again. There is nothing new under the sun.
Ecclesiastes 1: 10 Is there anything that people can point to and say is new? This kind of knowledge has existed for a long time in our previous generation.
Ecclesiastes 1: 1 1 No one remembers the past generation, and neither will the future generation nor the people after it.
Ecclesiastes 3: 14 I know that everything God does is eternal, neither adding nor subtracting. God did this to make people fear him.
Ecclesiastes 3: 15 Things happened earlier today. The future has happened. God makes the past reappear. (Otherwise God will find out what happened)
Ecclesiastes 9: 16 I told you that wisdom is better than strength. However, the wisdom of the poor is despised and his words are not kept.
Similar remarks in Greek myths and legends
Most planets in the sky will return to their original orbits in 25 million years. The universe is just, it gives everyone the same opportunity-25 million years! In 25 million years, we will experience what we are experiencing now again and meet the people we meet. ......
[Edit this paragraph] Hawking's explanation
Hawking explained that after the time traveler went back to the past and changed history, the timeline diverged, and the bifurcated timeline opened another period of history. However, if we can go back in time, we may break the law of causality. Therefore, grandma's paradox is also explained in this way: because time and space are related, grandma was killed, and the world was divided into two due to historical changes, resulting in a branch of time and space. Then I don't exist in this space, but my grandmother in another space still exists, so I still exist.
Another kind of doubt
I do not exist in this space. How can I go back and kill my grandmother? Without me, how could my grandmother be killed? So, I don't think there is a time reversal. Even in parallel space, it's just the same me with different fate, which doesn't mean I can go back to the past. Suppose this "past" is another space, then this space will always lack an "I" without an "I", maybe there are infinite universes and infinite "I", but one of the infinite I-an infinity cannot be ignored. Therefore, I think there are still contradictions. As for the existence of parallel space, some scientists may be able to prove it through experiments, but it is difficult to understand.
[Edit this paragraph] The theme of science fiction works
Since mankind went back to the past and was established in theory, "time machine" and "time travel" have become widely used themes in science fiction works. The "Time Machine" first appeared in 1895 Wells' novel The Time Machine. The idea at that time was only the author's fantasy. It was not until the advent of special relativity and general relativity that this idea began to have a certain physical basis, and science fiction movies with similar themes also had a scientific basis. It is because of science that there will be an intriguing story between science and fantasy. For example, in the sci-fi comedy Back to the Future, the protagonists Martin and Brambo travel between the past and the future in a time machine, interacting with people in that time and space, thus causing a branch of time and space and creating an ending different from the original time and space. In this film, the director vividly shows the causal relationship caused by the branching of the world due to historical changes, making this series of films become classics.
[Edit this paragraph] The definition of "post-parallel universe"
This parallel universe, which is differentiated from the new parallel world because of time travel and changing history, is called "post-parallel universe". Since there is a future, there will naturally be a first. The most typical example is Looking for the Universe, in which Jet Li's parallel universe is called "the first parallel universe", that is to say, whether you play or not, an infinite number of universes already exist, and you can run around in it if you have the skill.
This is close to nonsense, but experts say that the imagination in science fiction movies cannot be regarded as nonsense, because even if some of these imaginations have no scientific basis, they will affect science by expanding people's imagination. If we go to a higher level, the world created by Looking for the Universe can involve the content of quantum physics.
[Edit this paragraph] Interpretation of Planck Constant
If we explain the present universe from Planck's constant, it is easier for us to demonstrate the possibility of parallel universes.
Planck constant is the most basic unit of energy expression. On the planet where we live, every substance has an inseparable unit. We usually use atoms to represent this smallest unit. Similarly, every substance has energy, some large and some small, so energy should also have the smallest unit. In physics, this basic unit of energy is called Planck constant. The energy contained in any substance is an integer multiple of Planck's constant, but this is limited to the world we live in.
If we extend this law indefinitely, there will inevitably be a world where Planck's constant is not what we know as Planck's constant. For example, "1" is used to represent the value of Planck constant in our known world, that is, "Planck constant". If the value of Planck constant in another world is "2", then the other world is based on Planck constant "2". Moreover, there are countless desirable values from 1 to 2, so the world that may exist in parallel should be endless. But why can't we see them and feel them? If the positions overlap and we meet and can't see each other, will we meet? The answer is no, and the most direct examples of the relationship between the two are odd and even numbers. Odd numbers and even numbers will never intersect, they will always exist in parallel, so when they meet, they will pass through each other's queues unimpeded, which means it is impossible to perceive each other, let alone collide. Similarly, two worlds with different Planck constants, like a row of odd numbers and a row of even numbers, have different minimum units of energy, which divide us into two spaces, unable to perceive each other, let alone collide.
Although theoretically such a space-time can generate an infinite number, it can't really extract multiple values from it like odd and even numbers. By solving Planck's constant equation, scientists can only get a few comprehensions of the equation, from which they can construct several possible parallel spaces. However, under the influence of quantum physical uncertainties, these parallel spaces may also be unstable. If parallel space consists of these uncertain Planck constants, they may die out.
[Edit this paragraph] Parallel space in physics
First, start with the simplest zero dimension. The so-called dimension is the vector unit (direction unit) used to measure space, for example, the dimension of one-dimensional space is "X (length)", the dimension of two-dimensional space is "X, Y (length, width)", and so on. Because there is only one point in zero-dimensional space, no matter from any dimension, this point has no direction and length, so it has no dimension and can only be represented by 0, which is the so-called origin. Similarly, there is no lower space. So zero-dimensional space can only be projected to a higher level space.
Let's talk about one-dimensional space first. One-dimensional space has a direction, which can be written as a number axis if it is represented by geometry. If an object in a one-dimensional space wants to go directly to a certain point in its own space without going through other line segments, it can do so as long as it breaks through one dimension and comes to two dimensions, because it can randomly select a section of this space from the outside to enter. But to do this, it must have a premise, that is, it must become an object in two-dimensional space, because two-dimensional space has one more dimension than it. As an independent object in one-dimensional space, it is only an object whose dimension is infinitely close to zero in two-dimensional space (X axis and Y axis), and physical common sense tells us that the existence of infinity close to zero can be completely ignored, so it will not exist. Therefore, if it wants to exist in two-dimensional space or enter the one-dimensional world from the outside, there are only two ways: increasing the dimension and spatial projection.
Adding dimensions is manufacturing space. For example, if a line segment on a straight line wants to go directly to another point on the straight line, then it can create a new one-dimensional space in this two-dimensional space to connect a point in the original space, so as to achieve the purpose of crossing this space. If it wants to create a two-dimensional space, it must add dimensions, which is called creating a different-dimensional space. It can separate a new space from a certain point in the original space. It looks as if both belong to one-dimensional space. But because these two spaces exist in higher dimensions, they form a framework of two-dimensional space, and these two one-dimensional spaces are parallel to each other. We can call this kind of parallel space intervention parallel space (hereinafter referred to as dry leveling).
Spatial projection is another method. As we all know, two-dimensional space contains countless one-dimensional spaces, two of which are parallel or intersect (there can only be one possibility of parallelism). Two intersecting lines produce a point at the intersection, which extends outward from here along two spaces at the same time. In these two extended spaces, there are countless spaces crossing in, so there are also countless shrivels. And those dry flats are also disturbed by more dry flats. In this way, all spaces will leave the projection of all other intervening spaces. However, in a higher dimensional space, this interference will be minimal. At this time, only two parallel spaces interfere with each other the most (because each has a projection in the other space). And if one of the spaces wants to enter another section of their own space, just enter the nearest parallel space and then return to their own space along the opposite point of another space. However, because I have innuendo in another space, if I want to enter and survive, I can only destroy my innuendo in that space, otherwise I can only use the first method to create another space.
Also pay attention to the speed of space extension. For example, two parallel parallel spaces have different extension rates, in which β space is faster than α space. Then when it enters β space from a point in α space, it will move forward a little or not move at all. When it returns to alpha space, it will find that it has advanced a lot (this is the so-called one day in the sky and one year on earth). In fact, the units of each other's space are the same, but the relative elongation is different.
So how are dimensions measured? As we all know, one dimension is length (x), two dimensions are length and width (x, y), and three dimensions are length, width and height (x, y, z). From the measurement of the first three dimensions, the extra dimension in the higher-level space is actually not available in the previous space, and the objects in each space can manipulate their own vector direction (for example, one-dimensional space can change the positive and negative direction and length, two-dimensional space can change the length and width, and three-dimensional space can change the length, width and height). Then think about it carefully, how many dimensions should our space have?
Many people think that we are in a three-dimensional space. Maybe the geometry teacher will teach us, but after college, the teacher will tell us that we are actually in a four-dimensional space instead of a three-dimensional space. Because we ignore a very important vector unit-the attenuation of energy. Some people may ask me, don't we all use time to measure the world now, such as what we did at 8 o'clock and what we did at 9 o'clock? According to you, we should be in five dimensions. But I ask you to think about what this so-called time evolved from. Think about when there were no clocks before, we watched the sunrise and sunset, the hourglass and the digital symbols carved by stones on wood. So what are these changes? These are all caused by energy attenuation. All concepts of time are inferred from the decay of energy on the earth or in the solar system. Imagine, if one day the earth's rotation speed slows down, will time increase? A healthy person died at the age of 70, and this time he died at the age of 40, because a year has become the past few years, and its energy attenuation value has not changed unless you change it artificially.
So now let's write down the dimension units of our four-dimensional space: length, width, height and energy attenuation value (x, y, z, φ). Inference from one-dimensional to three-dimensional, if we want to enter a higher-dimensional space, we need to create more values in a certain unit space than it can hold, that is, to create a four-dimensional space with ultra-high energy output, thus making our parallel space. This is the technical basis of my work. Because the extension rate of each parallel space is different, even in the space that starts at the same time, the degree of development is different. I named the unit used to measure this rate in the fifth dimension as the cosmic year.
[Edit this paragraph] Summary
There is a well-known experiment in which an electron passes through a crack, and its position on the screen is not a linear projection of the crack, but an angle. If a large number of electrons are accumulated, interference fringes will be produced, and these electrons will pass through two cracks at the same time and interfere as they pass through two places at the same time. However, if we install detectors in each crack, electrons will only choose one crack to pass through, and there will be no interference. How to explain this strange phenomenon? Physicists also put forward the term "parallel universe". They believe that the electron actually still passes through two cracks at the same time, but in our universe he passes through one of them, and in the other universe he passes through the other, thus making up for the missing state in this world. It is quite possible that the parallel universe existed originally, but we can't prove it from experiments at present.
Then, for the "grandmother paradox", it can also be said that the universe has countless parallel spaces, so it can also produce countless parallel times. Even if we unfortunately killed my grandmother, I can't exist in this time and space, and my grandmother in another time and space is still alive, so I still exist. Accordingly, there is no difference between "front position" and "back position" in parallel universe. Everything is moving and splitting, as small as a particle, and it has been splitting, so the world has been splitting. For example, walking, I am walking on the road, and there may be two roads ahead at any time. I'm considering whether to choose left or right. So, the world is divided in two in my choice. One I'm leaving, the other I'm leaving. This division determines the possible fate of my world. If I choose to leave, I may meet a beggar in the next second. Then, the world began to split again, and I had to decide whether I needed charity or not. Walking on the right, I may meet a young girl and have the opportunity to walk with her. Isn't it wonderful? Fate has different results because of choice. This is vividly reflected in the sci-fi movie Foreseeing the Future starring Nicolas Cage.
When it comes to causality, we think of the "butterfly effect". Quoting the explanation on the Internet, "A butterfly in the Amazon basin of South America, occasionally flapping its wings, may cause a tornado in Texas, USA. The reason is that the movement of butterfly wings leads to changes in the surrounding air system and causes weak airflow, which in turn causes corresponding changes in the surrounding air or other systems, thus causing a chain reaction and eventually leading to great changes in other systems. " In dialectics, things are generally related. If the universe originated from a big bang, then the kinetic energy, direction, speed and so on at the moment of the big bang decided everything that happened afterwards, and perhaps also decided your life and death. Think about it this way, our real world is also full of incomparable fun!
However, everything is not a definite number, because there is uncertainty in quantum physics. For example, if an electron hits a proton, it may turn left or right. Because this uncertainty cannot be grasped, the two possibilities of electrons turning left or right also form two parallel universe worlds.
[Edit this paragraph] The question of parallel space
Some people understand the theory of relativity this way: if a clock moves away from the origin at the speed of 0.5 times the speed of sound, what phenomenon will we hear?
In one second, it reported 1 s from the origin, but we heard this event at the origin, and another 0.5 seconds passed, so we found that when the local clock was 1.5 seconds, the remote clock reported 1 s, the local clock reported 3 seconds, and the remote clock reported 2 seconds, that is, we ignored the measurement time. The faster the speed, the slower the clock. Beyond the speed of sound, we will catch up with the sound made before the clock, that is, we will hear the clock strike three times to report three points, then hear the clock strike two times to report two points, and then hear the clock strike 1 report 1 point. This is the phenomenon of supersonic time to go back!
Clock slowing, scale contraction, superluminal time to go back and other phenomena can be achieved by sound testing.
Einstein's own understanding is that speed is infinite and "absolute simultaneity" is meaningful, but the upper limit of observation speed is the speed of light, so "absolute simultaneity" is meaningless.
It shows that Einstein sometimes understands that relativity is a measurement problem caused by the slow speed of light. If the measuring speed is infinite, the relativity at the same time does not exist. For a group of blind people, the upper limit of measuring speed is the speed of sound, so Einstein's great theory for them will be the theory of relativity of speed of sound, but it can't be concluded that the speed of sound is the fastest.
Time is a parameter set by human beings to express natural processes. It really should be like Newton said, no matter other events pass evenly, other times do not meet the definition. Therefore, time will not go back. There will be no time to travel.
Parallel space is put forward to solve the logical paradox after time backtracking in Einstein's theory of relativity. If the skin does not exist, how can the hair be attached? If the new theory of relativity denies going back in time, there is no need for parallel space to exist.
Refer to the entries in Baidu Encyclopedia: Relativity, Principle of Invariance of Light Speed, Superphoton, Time Process, Lorentz Coordinate Transformation, Clock Slow Effect, Inverse Relativity, Twin Paradox, Speed Effect, Superlight Speed, Lorentz Transformation, Limit Speed, Special Relativity.