How Ingenious Our Universe Is

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This is a universe full of miracles. The biggest miracle is that it breeds life and produces intelligent life that can observe and think about the universe. To get to this point, many prerequisites are needed, such as large-scale cosmic structure, the existence of galaxies, stars, planets, chemical reactions, the origin of life, etc. These are all coincidences with incredibly small probabilities.

The essence of the universe is physics (this sentence is questionable), and its operation is governed by physical laws. Among the many physical laws, there are a large number of physical constants, and the values ​​of these constants determine the final form of our universe. It can be said that all coincidences and miracles in the universe are due to the fact that the values ​​of these constants fall within some very small ranges. If the values ​​of these constants change slightly, our universe will be completely different. Not only will it not breed life, but even galaxies and stars will not appear.

Therefore, people often call such a universe a fine-tuned universe or a universe on the knife-edge.

Let's take a look at how outrageous the accuracy range of physical constants is required to achieve the current state of the universe.

1. The gravitational constant appears in many physical laws, from Newton's law of universal gravitation to general relativity, and is crucial to the macroscopic structure of the universe. The value of this constant should be familiar to everyone: 6.67 X 10^-11.

If the gravitational constant is 10^-36 less than its current value, a star will not be able to exist stably. Its own gravity cannot compete with the radiation pressure from the core fusion, and it will collapse in an instant.

If the gravitational constant is 10^-40 greater than its current value, under the influence of excessive gravity, the universe will be full of black holes and there will be no more stars.

10^-36 is a number that is too small for the human brain to understand. The following example may help you understand it. If you connect 10^36 grains of sand with a diameter of 0.1 mm, its length will reach 114 times the diameter of the observable universe (93 billion light years). At such an unimaginable length, if you remove a grain of sand, the entire universe will collapse.

In addition, there are other parameters that play an important role in the current state of the universe. Some of them are physical constants, and some are the result of multiple constants acting together.

2. The efficiency of stellar nuclear fusion is 0.007, which means that when hydrogen is fused into helium, 0.7% of the mass is converted into energy. This parameter is determined by several other physical constants, including the magnitude of the strong interaction force. If the value of this parameter is 0.006, complex chemical elements will not exist, and complex chemical reactions on which life activities depend will not occur. If the value of this parameter is 0.008, all hydrogen elements will be quickly consumed after the Big Bang. However, not all physicists agree with this view. They believe that as long as the increase in strong interaction does not exceed 50%, hydrogen elements can exist stably for a long time.

3. The density parameter of the universe is the ratio of the matter density in the universe to the critical density (critical density), and this value is approximately equal to 1. If the matter density of the universe is too large, dark energy is not enough to drive the expansion of the universe, and the universe will shrink rapidly before the Big Bang. On the contrary, if the matter density of the universe is too small, it will not provide enough gravity to form stars.

4. The cosmological constant describes the ratio of dark energy density to the critical energy density of the universe. This constant is on the order of 10^-122. This tiny value determines that it can only work on a scale of 1 billion light years. If it were not so small, stars and galaxies would not be able to form.

5. The third lowest energy state of the carbon 12 atom is 7.656MeV. If this value is lower than 7.596MeV or higher than 7.716MeV, the carbon produced by stars will not be enough to support carbon-based life. Similarly, to produce the oxygen element required to meet the needs of life on Earth, we require a range of 0.5% for the strong interaction force and 4% for the electromagnetic force. Of course, if you believe that other elements, such as silicon, can also support life, you can ignore this.

There are many such examples, such as the fine structure constant, the dimensions of the universe, etc., which will not be repeated here. However, one thing that cannot be ignored is that the final state of the universe today is the result of the action of all these factors. They must fall within the specified range at the same time. Therefore, the probability that we get the universe today is the product of all the small probabilities. You can probably imagine what kind of jackpot we have won.

Whether from a scientific or philosophical point of view, a precisely tuned universe is an unavoidable problem. So why do we get a universe that seems to be designed for us?

First of all, we must consider that physics has not yet developed to the point where we can answer all questions about the universe. Physical constants that seem independent of each other at present may be related to each other at a deeper level. In the future, we may find that the probability of the current state of the universe is much greater than the calculations above.

Let's take a look at various attempts to explain the fine-tuned universe.

1. Intelligent design

An easy answer is that the universe was designed by a higher level of intelligence, whether it is God or an alien that we cannot understand. The purpose of designing such a universe is to breed life in it, or it is an experiment to see how long it takes for the budding of life to spread throughout the universe. If we extend this view, we can even assume that our universe is just a virtual world of a computer system.

Those who oppose this view point out that it is too inefficient to create such a huge and extremely old universe just to feed a few creatures on an inconspicuous little blue planet (after all, we have not found reliable evidence of extraterrestrial life). In fact, this does not effectively overturn the view of intelligent design, because the first bacteria in the petri dish may also ask the same question.

However, the extent to which this answer solves your problem depends on the piety of your faith. If you think that an all-powerful God is the ultimate answer to all problems, and the existence and origin of this God himself are unquestionable, then you don’t have to think about it anymore. On the contrary, if you still want to use the scientific research method to think about the principle of the existence of intelligent designers themselves, you will find yourself falling into an infinite loop: intelligent creatures that can design the universe must be more difficult to understand than the universe itself.

2. Anthropic Principle

Supporters of the anthropic principle believe that "if the universe is not precisely adjusted to its current state, humans will not exist, nor will they observe and think about the universe."

There are many versions of the anthropic principle. Among them, the weak anthropic principle believes that the possible values ​​of parameters in physics and cosmology are not completely equivalent, and the universe prefers those values ​​that allow carbon-based life to evolve.

The strong anthropic principle goes a step further and believes that the universe must have properties that allow certain stages of life to develop. And the final anthropic principle believes that: information processing processes containing intelligence will definitely appear in the universe, and once they appear, they will not perish. Opponents of the anthropic principle argue that this view can neither be tested nor falsified, and it reverses cause and effect. Humans evolve to adapt to the universe, not the universe adapts to humans. Hawking also believes that our universe is not as special as described by the anthropic principle.

3. Multiverse theory Among many explanations, multiverse theory is probably the view that is most closely related to physics. This view holds that all values ​​of physical constants are possible and must exist. They just exist in different universes. The universe we live in happens to get the existing constant values, so it finally gets the current state of the universe, and intelligent life that can observe and think about the universe appears. Other universes get different constant values, so they may collapse quickly after the Big Bang and return to the singularity, and will not form galaxies and stars; in some universes, stars may be extinguished in the moment of ignition, and life cannot evolve.

There are many different versions of the multiverse hypothesis in current physics. The hypothesis that can be used to explain the precisely adjusted universe is probably only based on string theory or M theory. For details, please refer to What is the relationship between string theory and parallel universes? However, neither string theory nor multiverse theory can be confirmed at present. Similarly, the precisely adjusted universe is also a question without an answer.

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