7.3 The Great Sieve
American scholar Robin Hanson did an in-depth study of Fermi’s Paradox and wrote a paper on the wisdom of the universe, “The Great Screening, How Far Have We Goed? “. The general meaning is as follows: Judging from the appearance of the universe, the universe is in a state of great silence, and no signs of life and civilization have been found. From this, it can be inferred that civilizations that can spread on a large scale in the universe and last for a long time are extremely rare, and may not even exist at all. Then there is an inference:
There is a huge screening mechanism between the inanimate matter in the universe and the intelligent civilization that continuously spreads (Great filter, some people translate as the big filter), and it is extremely difficult for the intelligent civilization to pass this screening. There may be many layers of sieves, such as one layer for cells that have evolved to replicate, one layer for manufacturing tools, one layer for avoiding nuclear war destruction, etc. The author listed nine possible sieves and analyzed them layer by layer.
Big screening, like natural screening, a more reasonable and possible explanation for human beings’ inability to discover other civilizations is that a certain sieve is particularly sad, and there will be very few cosmic civilizations that can pass, and most civilizations are here. The halberd fell into the sand, so humans have not been able to easily discover other alien civilizations.
I personally believe that the division of civilization levels can be marked by the distance the group can reach
At the first level, the primitive level, the distance that individual physical strength can reach is roughly 100 kilometers, which is typically primitive society.
At the second level, the distance that can be reached with the aid of primary tools is the diameter of the planet. Magellan’s circumnavigation did this. This is also the limit of an agricultural society.
The third level, the distance that can be reached with the help of chemical energy engines, is the farthest the satellite where the planet is located. Humans did this in 1969.
The fourth level, freely navigating in the star system, humans are currently powerless.
The fifth level, interstellar navigation.
Human beings can now be said to have reached the third stage, and they can barely reach Mars with the help of chemical rockets, but other planets are powerless, and flying out of the solar system is far away.
In theory, as long as humans can reach the fourth level, even if they are eventually trapped in the solar system, the cost of launching unmanned probes will be very low, and humans will leave a lot of traces in the universe.
The same goes for other civilizations.
Now the question is, why is the universe so quiet?
In my opinion, from the current theoretical reserve, technological level and complexity development trend, the sieve that is difficult to pass is the key technology for the leap from the third level of civilization to the fourth level: controllable nuclear fusion.
Considering the distribution of resources in the universe (mostly light elements), after any civilization recognizes the principle of star luminescence, controllable nuclear fusion is a rational choice for energy and power.
The significance of controlled nuclear fusion cannot be overstated by any means.
On the one hand, any civilization that can achieve controllable nuclear fusion has theoretically achieved an almost infinite flow of negative entropy. Even if there is no qualitative change at the technical level, it can survive almost forever. At this stage of civilization, the cost of launching unmanned detectors will become very low, and the number of detectors that will eventually be launched will reach an astonishing level in the near-infinite duration of civilization.
On the other hand, if controllable nuclear fusion can be achieved, the civilized space propulsion technology may undergo a qualitative change (this is also what the so-called new energy cannot do). Qian Xuesen pointed out decades ago that with controllable nuclear fusion, the speed of spacecraft will be greatly increased, and navigation in the star system will become easier. Mankind will become a true fourth-level civilization. And any civilization that can develop to the fourth level has no lack of adventurous spirit in its bones. If there is controllable nuclear fusion technology, I believe it will start to build interstellar spacecraft. Even if it is gone, the controllable nuclear fusion technology makes it possible for the ecological self-circulation system. The spacecraft can last for tens of thousands of years, and some detectors will Departing from generation to generation, flying to the vast starry sky.
If so, the starry sky is definitely not as quiet as it seems now.
1 Civilization and technology
1.1 Rough talk about paradigm
1.2 The paradigm shift experienced by human civilization
1.3 Science Theory stagnation
1.4 The gap between science and technology
2 The paradigm spring dream advocated by scientific and technological interest groups: the so-called technological explosion
2.1 Rendering and brainwashing
2.2 Papers and patents: the absurdity behind astronomical numbers
2.3-2.4 The bit world and the real world / Part and whole
3 The shadow outside the paradigm spring dream
3.1 The technological dilemma faced by humans
3.2 Numerous technical gimmicks
3.2.5 New gimmicks in recent years
3.3 Frustration of PhD laborers and biotechnology
4 The dilemma of low-entropy body and the technical steps faced
4.1 From the second law of thermodynamics
4.2 The backbone and forks of the technology tree
4.3 Forever 50 years and controlled nuclear fusion
4.4 The future is not always better
5 The Pit Before 5 Steps: The Fate of Human Society
5.1 The Sociological Significance of Dissipative Structure Theory
5.2 The disappearance of the big competitive environment
5.3 Differences erased by globalization and the thermodynamic balance of human society
5.4 Aging self-locking
5.5 How to fill the hole?
6 The essence of 6 steps: complexity devil
6.1 What is complexity
6.2 Two rules behind the complicated world: survival of the fittest and expectation of return on capital
6.3 Technological progress and technological revolution: changes in complexity
6.3.1 Evolution example of transportation / power system
6.3.2 The characteristics and complexity of the technological revolution
6.3.3 The high-complexity science devil facing
6.3.4 Dilemma originating from technical foundation
6.4 Many evil consequences brought by high complexity ( more is different)
6.4.1 I know you have a life and death race
6.4.2 Maintenance costs
6.4.3 Negative feedback from society
6.5 Simple mathematical derivation
7 Silent Star implied by the prospect of terror
7.1 The Great Silence and Fermi Paradox
7.2 Three scenarios for contemplating extreme fear
7.3 The Great Sieve of the Universe
7.4 A small match
8 reflection and summary
8.1 The tragedy of Easter Island
8.2 Calmness does not mean pessimism
8.3 R&D requires a paradigm revolution