Kepler 186f-Find a habitable alien planet, why is that bad news?

April 17, 2014, scientists announced that they found a planet 492 light-years in the direction of the Swan: Kepler 186f. What is special about this planet is that it is the first planet found outside the solar system that is almost the same as Earth and is located in the so-called habitable zone. In other words, the distance between it and the star is just right, and we can expect liquid water on the surface of the planet--and life ...

This is not the first alien planet that scientists have announced could be habitable. What is not mentioned in this news, however, is the likelihood that we estimate that human civilization would be extinct in the short term, as this discovery has been slightly elevated. All of this is attributed to a concept known as the "Big Filter" (DA filter).

Humans are probably afraid of being alone. Many ancient legends around the world can be found in other habitable worlds. And since it has been confirmed by modern astronomical observations that they are not the pride of creation, but rather the pianan of the mundane corner of the vast universe, we have begun to invoke the knowledge and technology of the modern scientific system, and to seriously consider the possibility of extraterrestrial life and even extraterrestrial civilization, On the one hand look for clues to their existence-including finding life in an extreme environment that is thought to be comparable to extraterrestrial beings on Earth.

So we found the paradox: based on the current knowledge of physics, chemistry, biology, cosmology, and society, we believe that the Milky Way should have been filled with interstellar civilization, but not only on Earth, but not in the evidence that aliens have visited, but also in the telescope we can not see the alien spacecraft or the project fleeting figure --even a radio signal cannot be received.

Enrico Fermi, an American physicist Enrico, pointed out the contradictions in an informal discussion in 1950, which seemed unusual. The universe is already more than 10 billion years old, there are only hundreds of millions of stars in the Milky Way, and the sun that breeds us is only one of the younger. So even considering the speed of light is not a breakthrough, we should not be so lonely. In 1975, US astrophysicist Macker Hart (Michael H. Hart) discussed this possible explanation in a detailed paper. After that, the problem is often called the Fermi-Hartley paradox (Fermi-hart paradox).

The concept of large filters is the Robin Hansen of Robin Hanson, an assistant professor at George Mason University in the United States, to try to answer the Fermi-Hartley paradox. His evolution from a barren wasteland to an expansive interstellar civilisation is roughly divided into the following 9 stages:

Suitable planetary systems (organic and possibly habitable planets);
Self-replicating molecules (such as RNA);
Simple (prokaryotic) Single-cell life;
Complex (eukaryotic) Single-cell life;
Sexual；
Multicellular life;
Linked larger, use tools of animals;
We are at this stage;
The expansion of interstellar colonization.
Hansen believes that the fact that the universe is empty of vision shows that at least one of these 9 stages-or more phases that may be subdivided-is difficult to achieve. No matter what the step is to stop the final implementation of phase 9th, it is called a "big filter".

The first question that deserves human attention is where the big filters work. If it were in the 8th step, we could have bellies ourselves, the future is still ahead, and since earth can do it, there is no reason to think that other planets will not reach our stage or even go further. If it is just between steps 8th and 9th, it means that the test of life and death is behind it. Given that no other civilization has arrived at the 9th step, we may not be too optimistic about our own fate.

Ultimately, the answer to the question of where "big filters appear" needs to be sorted out to find out what bottlenecks prevent the 9th step. The question has been debated for more than 50 years. Here are a few possibilities for large filters, which were summed up by Andrew Sch de Bitty, a scholar at Oxford University in the UK, and Robin Hansen.

Maybe the earth is really lonely in the universe. Although some people think that since life has already appeared on Earth, it must be relatively common, but Schneider-bitty points out that the observation choice effect complicates the analysis of the problem. There are only 1 samples (ourselves as observers), and it is difficult to determine the probability of life appearing--we may well be the exception. The art of asteroid intrusion into the Earth's atmosphere, Earth's life has survived this catastrophe more than once in evolutionary history.

By examining the history of life on Earth, it is not difficult to find that the evolution of complex life requires too many perfect conditions. Not only does the Earth need to be located in the habitable zone of the sun, the sun is also far away from the galactic center to avoid destructive radiation; Our gas giants must be large enough to sweep up asteroids that run to Earth's orbit; Our surprisingly large moon also stabilizes the inclination of the axis so that we can enjoy different seasons. This is only a few prerequisites for complex life needs. The emergence of symbolic language, tools and intelligence also requires such "perfect conditions".

Hansen doesn't believe this one. The following two steps are easy to implement: a mammal of ordinary intellect evolved the same ability as human beings, and the other was the ability to create advanced civilizations like human beings. It took only millions of years for ordinary intelligence animals to evolve into humans. He said: "If you kill all the humans on Earth, but leave life--including animals with larger brain capacity--the intelligence will not take too long to reappear." "But some of the filtering steps before that may take longer." From simple prokaryotic (cells without special organelles) to more complex eukaryotic cells spanning more than 1 billion years on Earth, multicellular animals and the brain appear for almost 1 billion years.

In this scenario, powerful aliens are hidden in the shadows waiting for any detectable intelligence to be eliminated. Hansen doesn't think this is justified, because if there are a variety of violent warrior races, there will be a cube. "As a kind of equilibrium, you have to let all these competing rage fighters try to destroy each other," he said. ”

Perhaps, the massive events that occur on the extraterrestrial planets look just like natural phenomena. Hansen says this may sound improbable, because all the cosmic phenomena that we interpret as natural occurrences, whether pulsars or dark matter, are caused by advanced human processes, which would be an "extraordinary coincidence."

Just being on Earth is obviously risky. The impact of an asteroid, a beam of radiation from a nearby supernova, or a large enough volcano can end the civilization we know--or even most of our lives. "But there is a consensus that we have survived a series of such catastrophes," he said. "There is little likelihood that all life will be wiped out." "It's not even a wink," says Hansen, "if it takes 10,000 years for the surviving human to rebuild civilization." This can not destroy human civilization. "In addition, from a statistical point of view, these events will occur, but will not happen very frequently." "It is unlikely to happen this rare event for a century or 300 years," says Schneider Debity. ”

This is one of the most interesting points to explore, and indeed the most interesting. It means that big filters are the challenges we have to face in the future, and if the discussion of it can spur us to take a more introspective and prudent approach to technology, we can increase our chances of breaking the challenge. Over the past 200,000 years, humans have survived super volcanoes, asteroid impacts and natural epidemics. But after the advent of nuclear weapons, our survival record is only a few decades old. After some of the new technologies that may emerge in this century, the situation will be more difficult to assert. Through natural disasters, we may not be in their own invention of suicide technology slip.

Martin Rees, a Royal astronomer at the Cambridge Survival Risk Research Center, believes that advances in biotechnology have the potential to cause disaster, Rees. Other scientists, such as Stephen Hawking, Max Tegmac (Max tegmark) and Stuart Russell (Stuart Russell), as well as the Cambridge Center, are highly intelligent and attractive but lack full research possibilities, expressed serious concern.

However, in many specific areas of technology, it is still worth further argument whether it is possible to form a large universal filter. For example, Schneider Debity that climate change may be a catalyst for extinction, but all civilizations are encountering similar policy failures that sound outrageous. The rise of machine intelligence or distributed biotechnology can indeed lead to the end of human civilization, but it may not prevent the formation of interstellar civilizations-if robots replace us, they will also come to the universe and leave their own civilization footprints. Even if the rise of machine intelligence replaces human civilization, it may not prevent the formation of interstellar civilization.

Hansen believes that the key to the fate of our civilization is to focus on what we can control. This means that we should make a list of the things that might theoretically kill us, and then find ways to solve them.

In addition, we can estimate from the macroscopic view of the whole galaxy through astronomical observations, the larger filter is more likely to be in front of us or behind our bodies.

When the Fermi-Hartley paradox was just proposed, it was thought that the planet itself was scarce. But since then, astronomical tools have found thousands of alien planets, and it seems to be just the tip of the iceberg.

However, every Earth-like planet in the habitable zone, such as Kepler 186f, is likely to be reduced by one point as the planet is the only planet that can sustain life. Large filters are more likely to lurk on the path between habitable planets and thriving civilizations.

It would be a terrible news for mankind to have the wisdom of life on Kepler 186f, because it would push the position of the large filter further into the technological phase of the development of civilization. It would imply that we and our alien companions are facing disaster.

As far as Kepler 186f is concerned, there are still many reasons to think that intelligent life may not be there. The atmosphere may not be strong enough to prevent freezing, or the planet has been locked by tides, creating a relatively static environment. It is indeed a celebration to find such bad conditions.

As the philosopher Nick Strome (Nick Bostrom) said

The Silence of the night sky is most precious ... In the exploration of extraterrestrial life, no news is good news. That heralds a better future for mankind.