— 1—
This book begins with the macro-scale universe. Our universe began with the Big Bang 65.438+038 billion years ago. The cosmic microwave background radiation shows that the soaring universe actually happened before the Big Bang!
Constant density and the soaring of matter and space have doubled, smoothing out the large-scale differences in the universe, making the present universe look similar in all directions. The skyrocketing decay solidified the quantum fluctuation of the universe, which made matter gather after the Big Bang, resulting in large-scale fiber structures of stars, galaxies, clusters of galaxies and the universe, such as the "Great Wall of Si Long".
Moreover, this skyrocketing is eternal and never stops! Because the expansion needs an energy field, and the existence of this energy field ensures that the expansion process will continue and never stop. Inflation will have a certain probability of random decay, and the big bang after decay will produce a material universe. This brings a result that inflation is exponentially split, so there are infinitely many universes that decay randomly-this is the second parallel universe mentioned in the book.
—2—
What about the first parallel universe? This has to go back to the cosmic microwave background radiation, which is the observation result of light reaching the Earth 400,000 years after BIGBANG. Looking out from the earth, we can see the sun eight minutes ago, the Milky Way galaxy dozens of light years ago, the cluster of galaxies hundreds of thousands of light years ago, and the place where atoms formed 400,000 years after the Big Bang. The outermost light is like a ball of light around us, making it impossible for us to see further and earlier time and space.
The author makes an analogy, just like a person standing in a dense fog, he can only see the Fiona Fang of tens of meters, which is our Hubble volume. Others standing elsewhere can also see Fiona Fang dozens of meters away, which is his Hubble volume. Starting from countless origins, we can see countless different Hubble volumes, and they can actually overlap! This is what the author calls the first parallel universe. They are physically related, so they follow the same physical laws, for example, Planck's constant is equal to 10-43.
The second parallel universe was produced during the explosion and decay, and it can never be connected. The quantum effect of decay will produce different physical laws, such as higher light speed, such as four-dimensional space …
—3—
The third parallel universe is the wave function explanation of quantum mechanics. The author opposes the traditional Copenhagen interpretation and thinks that the wave function will never collapse! We can't observe the macroscopic quantum effect because the decoherence theory shows that every interaction of a large number of particles in the universe will exchange information, making the particle information public and certain. Observation is nothing more than exchanging information. It is not mysterious, and human consciousness has no special position in quantum mechanics.
Then why do we toss a coin with random heads and tails? How does the randomness of the world come from? The author says that seemingly random doesn't mean really random. The decimal of root number 2 still looks random! The change of wave function of Schrodinger equation with time is certain, and the function itself is not random.
Now the brain hole is coming. Every time you flip a coin, the universe splits in parallel! A coin in the universe is facing up, and a coin in the universe is facing up. In both universes, you will feel that the result is random! In fact, you just don't know whether you are in the coin upside down universe 1 or the coin upside down universe 2!
Of course, the universe is not divided into two, but into countless ones, because theoretically, the probability of any possible situation is not zero. For you in the universe, it is random; For each universe itself, it is an address. Moreover, this address can be easily generated mathematically, such as giving 2 a root sign.
So this is the third parallel universe, because quantum effects are everywhere, so the third parallel universe has been splitting.
—4—
And all this can be described by mathematics. Everything in physics is closely related to mathematics, and the laws of physics are mathematical formulas in the final analysis. Time and space in general relativity are mathematical structures, and the basic particles in quantum field theory are also mathematical structures. String theory, the most promising ultimate theory of physics, is also a mathematical structure.
Mathematics can deduce physics, physics can deduce chemistry, and in theory chemistry can also deduce biology, psychology and sociology ... The whole universe can be described by mathematics. Moreover, in mathematics, isomorphism equals identity, and eight apples and eight oranges are a collection of eight elements. Real chess is no different from computer-simulated chess in mathematics. So if a set of mathematical structures can completely describe the universe and the universe and this set of mathematical structures are isomorphic, then we can get the universe = mathematical structure!
Plato and Pythagoras believe that mathematics comes from the world of ideas, and people have not "invented" mathematics, but only "discovered" mathematics. Natural numbers can be found from 1+ 1=2, from negative numbers of 0- 1=- 1, from rational numbers of 1/3, from the square of 2*2, from irrational numbers of 2, and from-/kloc-.
Compared with the real universe that needs to be pushed first, the mathematical structure is more comfortable. The existence of mathematical structure ensures the existence of the universe it describes.
The brain hole is coming again A set of mathematical structures corresponds to a universe. If different mathematical structures are exhausted, different universes can be produced. This is the fourth parallel universe.
—5—
Finally, when the author predicts the future of the universe in his conclusion, it seems reasonable to question the nature of space.
Because of the different density of dark energy, our universe will eventually move towards great cold silence, great compression or great tear; But the author thinks that apart from these three endings, there may be a big rupture or death bubble in the universe.
We believe that time and space are continuous, and space itself is stable and can be stretched indefinitely. There is no reliable evidence. Space can be bent, can be bent into a black hole, can be stretched into an expanding universe, and can also transmit gravitational waves.
Perhaps space can condense or evaporate into another completely different phase as fast as the gas, liquid and solid state of water, such as "freezing" quickly, producing a large number of rapidly expanding dead bubbles.
In addition, just as smooth photos will eventually have granular pixels, stretched rubber bands will eventually break molecular bonds. After the space of our universe has expanded for so long, it is also possible to have granular properties after extreme stretching, and finally it will break.
If space is stretched from smoothness to granularity, the smallest structures, such as electrons and quarks, may break first, and the physical, chemical and biological properties based on them will cease to exist.
————————————
I just read the first five chapters, and I have a few questions:
1. I think Copenhagen explanation plus decoherence hypothesis is not bad. In this way, the collapse of wave function is no longer an anthropic principle, but the system is not isolated, and too many particles in the universe are irrelevant to each other, which leads to the collapse.
2. In addition, the theory of eternal expansion seems to need endless energy. Where does this energy come from?
3. Finally, it is difficult to understand that the density is constant and the space and matter are multiplied. The increase of space or matter will lead to the change of density. There must be a pressure conduction process to achieve the same density, right?
Eternal inflation should not have time to make the density consistent. For example, nuclear fusion has been going on inside the sun, resulting in the density of the core always higher than the surface.
————————————
I read Chapter 9 yesterday. The idea that the universe and mathematical structure are isomorphic is genius, but there are still some questions to be questioned:
1. Isomorphism is the same, which only holds in mathematics. In the real physical world, eight apples are not equal to eight oranges.
Mathematics is a process of constantly removing information in the process of abstraction. Eight apples and eight oranges are isomorphic because the information that they are different fruits has been deleted. To say that a certain mathematical structure is isomorphic with the universe is isomorphic with the dry universe without rich information, not the real universe.
This reminds us that reductionism alone can't fully understand the world, and even if the grand unified theory is obtained, the problems encountered in the real world will not disappear automatically.
2. Real-world computer modeling is also based on sampling and discretization, and it is also discarding information. After that, the sampling becomes more and more detailed, and more and more detailed models are added to approach the reality. However, in game modeling, it is very difficult to model the lighting of local environment. Is it difficult or impossible to completely simulate the real world?
In a letter from Silicon Valley, Mr. Wu Jun said that computers can only solve those computable problems in mathematical problems, which are only a small part of mathematical problems, and mathematical problems are only a small part of practical problems. If the world can't be calculated, then we still have to rely on evolution.
3. The author adopts the four-dimensional space-time view of general relativity in his argument, which shows that there is no difference between time dimension and space dimension, and four-dimensional space-time is a static mathematical structure.
However, no matter how similar time and space are, there is still a lack of an imaginary symbol in mathematics, and the time dimension and the space dimension are different. Otherwise, the world of three-dimensional time and one-dimensional space should also evolve into an agent.
In order to demonstrate the rationality of the existence of the third-level parallel universe, the author compares it with the first-level parallel universe, and shows that they can accommodate the same rich universe types in the "probability address" and are isomorphic. But if there is an essential difference between time and space, this isomorphism will not hold.
4. Even in the "probability address", the first-level parallel universe may not be able to accommodate as many universe types as the third-level parallel universe.
The author compares the Hubble volume with human vision in dense fog, indicating that there are countless parallel universes in the first layer outside the Hubble volume, and the boundaries of these parallel universes can overlap, and they are actually the same universe in physical reality. In other words, the concept of the first parallel universe is actually redundant. They are a universe.
Only the second parallel universe, which is soaring forever, cannot be connected, and there is a space with constant density between them. This restriction actually shows that the so-called first parallel universe is not infinite, but we can't observe it. Just like in ancient times, we thought the ocean was infinite.
5. What about the second parallel universe? It comes from the exponential division caused by eternal expansion, and its "probability address" is not necessarily as rich as the third layer.
In mathematics, infinity is also a component order, and the infinity of different orders is irreducible. The third-level parallel universe needs the split of "probability address" every moment, which is at least one order of magnitude more than the split when the second-level parallel universe rises and decays.
In the third parallel universe, a universe that is completely consistent with my past history but different in the future, it is necessary to make that universe have the same physical rules, the same quantum fluctuations, the same evolutionary history of life on earth, the same history of human society and the same personal history, and each requirement is an "infinite" order of magnitude, which cannot be offset by one or two "infinity". So I tend to think that that special third-level parallel universe, whether in the first or second-level parallel universe, can't exist.
6. In different combinations of space-time dimensions, only three-dimensional space and one-dimensional time and narrow physical constants can produce life. Only the universe corresponding to a certain mathematical structure can produce us. It is quite close to the intelligent design theory.
I haven't finished reading the last two chapters. If only the mathematical structure is comfortable, then why does it exist?
————————————
Seeing the problem of spatial continuity and the future of the big fracture universe, I haven't even finished reading a conclusion …
1. Contradictory optimism
If we believe Einstein's view of four-dimensional space-time, four-dimensional space-time is only a static structure, time is only an illusion, and a certain moment in the future is only a tangent plane of this static space-time structure, and the past and future, causality are illusions.
Therefore, the mathematical universe only needs to be described, and there is no need to calculate how it evolves. In that case, why predict the future and work hard for it?
If it is still useful to predict the future because you don't know your place in the universe, then changing the future is an idiotic dream. The future has already been written into the screenplay of four-dimensional time and space, and it does not depend on our efforts. Even free will is an illusion, and our efforts and hopes at the moment are already written scripts.