Scientists have proposed that everything in the universe is becoming more complex over time, a new theory that challenges the traditional view of evolution and suggests that intelligent life may be ubiquitous.

Why is everything in the universe getting more complicated? It's a fascinating question. In 1950, Italian physicist Enrico Fermi proposed the famous "Fermi paradox" when discussing extraterrestrial life with his colleagues: if there are intelligent civilizations in the universe, they should have enough time to spread across the stars, but why can't we see them? There is speculation that extraterrestrial civilizations may have self-destructed before becoming interstellar travelers. But there's a simpler explanation: intelligent life is extremely rare, and we humans are only a handful of exceptions in the universe.

However, an interdisciplinary team led by mineralogist Robert Hazen and astrophybiologist Michael Wong came up with a very different view. They believe that there is a natural law in the universe similar to the second law of thermodynamics, which drives the complexity of everything to increase over time. If this theory is true, complex life, and even intelligent life, may be far more common than we think.

The idea originated in 2003, when biologist Jack Szostak proposed the concept of "functional information" in an attempt to quantify the complexity of biomolecules such as proteins or DNA. He found that the key to measuring complexity is not the randomness of molecular sequences, but the functions they can perform. For example, some RNA molecules are firmly bound to a specific target molecule, and functional information measures how many other molecules are equally good at doing the job. Szostak has been experimentally proven to show that as the molecule is continuously optimized, the functional information will gradually increase.

Hazen was intrigued by the idea. In his research on the origin of life, he realized that distinguishing between "life" and "non-life" might be a false proposition. Chemical reactions occur on the surface of minerals and may be key to the birth of life, while functional information may reveal evolutionary processes from simple to complex. In 2007, he collaborated with Szostak to design a computer simulation, which calculated the function through an algorithm, and sure enough, it was found that the function information would grow spontaneously over time.

But this theory was silent for many years, and it was not until Wong joined the team in 2021 that the two found a breakthrough. Wong had been disappointed with the way he searched for extraterrestrial life, arguing that our definition of "life" was too narrow and that he might have missed a completely different evolutionary path. They brought together experts from physics, philosophy, biology, and other fields to try to look at the growth of complexity from a broader perspective.

In their view, biological evolution is only a special case of the universal laws of the universe. Whether it's minerals, chemical elements, or galaxies, complexity is increasing. In the case of minerals, the Earth's history has formed more and more complex minerals, and on Saturn's moon Titan, a hydrocarbon-rich environment may have given birth to complex structures like graphene. After the Big Bang, there were only simple quarks at first, then light elements such as hydrogen and helium, until stellar nuclear fusion produced more complex elements such as carbon and oxygen, and even supernova explosions gave birth to heavy metals - all of which pointed in one direction: the accumulation of functional information.

However, this theory is not without controversy. Critics argue that it is a stretch to extend the concept of "functional" to non-living systems. Functional information not only varies from environment to environment, but is also difficult to calculate accurately, so some have questioned whether this theory is verifiable. In contrast, Darwinian evolution, while explaining changes in past organisms, cannot predict the future, and the new theory seeks to fill this gap by outlining the possibility of a future universe.

More thought-provokingly, the growth in complexity is not always flat. In biological evolution, the emergence of the nucleus, the birth of multicellular organisms, the Cambrian explosion of life, the formation of the nervous system, and even the emergence of humans are all moments of rapid complexity. These "jumps" seem to open up a whole new space of possibilities, as Wong describes as "ascending to a new level". For example, at the beginning of life, molecules need to be stable for a long time, but when the molecules form an autocatalytic cycle, dynamic stability replaces thermodynamic stability, and the rules are completely changed.

功能信息的獨特性在於其語境性。RNA分子綁定不同目標時，功能資訊會隨之變化。這與生物進化中“舊物新用”的邏輯不謀而合——羽毛最初並非為飛行而生。進化不斷創造新的可能性，而這些可能性在早期甚至無法想像。3億年前的單細胞生命汪洋中，絕無可能突然冒出一頭大象，複雜生命需要一系列特定的創新鋪墊。

Physicist Paul Davies argues that biological evolution is unpredictable because it is self-referential: the emergence of new species changes the living environment of existing species, giving rise to more possibilities. Unlike physical systems, even if there are billions of stars in the Milky Way, they don't change the rules on their own. Plant developmental biologist Marcus Heisler points out that the increase in complexity opens up space for new strategies that are inaccessible to simple organisms, and that this openness is the magic of life.

Hazen further envisions that when complex cognition is added to it, the possibilities of the system will increase exponentially. Technological progress has allowed mankind to transcend Darwinian evolution, and if a watchmaker can "see", the efficiency of making a watch will be far greater than blind groping. However, does the inevitable increase in complexity mean that life, consciousness, and even higher intelligence are inevitable in the universe? Evolutionary biologist Ernst Mayr has argued that human-level intelligence is highly unlikely to reappear because it has only appeared once in the history of life on Earth. But the Hazen team believes that once life emerges, a leap in complexity may be inevitable, and wisdom may not be exceptional.

To test this theory, Wong proposed to look for clues in astrobiology. Life on Earth tends to select specific organic molecules, such as glucose, rather than randomly generated, which may be the result of natural selection. On other planets, a similar distribution of "non-random" molecules could be evidence of the existence of life. In addition, Hazen sees the potential of theories in cancer research, soil science, and even language evolution. For example, the evolution of cancer cells is more like functional selection than traditional adaptive competition.

Although the functional information is difficult to quantify precisely, Hazen believes that this does not prevent us from understanding the concept, just as we cannot accurately calculate the dynamics of an asteroid belt and yet successfully navigate a spacecraft. Whether or not functional information ultimately becomes the key to solving the mystery of complexity, scientists' quests for evolution, the direction of time, and the fate of the universe have made waves. This is reminiscent of the inception of thermodynamics, from the efficiency of the steam engine to the revelation of the arrow of time. Perhaps, we are standing at the starting point of another scientific revolution.

This article was translated from Quanta Magazine and edited by BALI.