Are humans unique and alone in the vast universe? This question, summed up in the famous Drake equation, has been in the most unruly and uncertain wing of science for half a century. A new paper shows that the recent discoveries of planets combined with a broad approach to the question make it possible to assign an empirically valid probability to the question of whether other technologically advanced civilizations ever existed
Even if the chances of advanced life developing on a planet suitable for incredibly simple life forms, still the human species is not the first high-tech species in the universe.
The study, published in the journal ASTROBIOLOGY, also provides for the first time pessimistic and optimistic limits for assessing the likelihood of the existence of advanced life outside of Earth.
"The question of whether advanced civilizations exist elsewhere in the universe has always faced three major uncertainties in the Drake equation," said Adam Frank, professor of physics and astronomy at the University of Rochester and one of the authors of the paper. "We have known for a long time how many stars there are in the universe. We didn't know how many of these stars had planets that might support life, how often life might evolve and lead to intelligent beings, and how long any such culture would last until it died out. "
"Thanks to NASA's Kepler satellite and other means of observation, we now know that at least a fifth of the stars have planets surrounding them in their habitable zones where temperatures exist that can support life as we know it. Now there is a limit to one of the three major uncertainties."
Frank said that the third big question - how long civilizations might survive is still completely unknown. "The fact that humans have had the basic technology for about ten thousand years does not really tell us whether in other societies the cultures will last such a period of time or longer", he explained.
But Frank and his co-author, Woodruff Sullivan of the Astrobiology Program at the University of Washington's Department of Astronomy, found they could overcome this simply by broadening the question.
"Instead of asking how many civilizations exist now in the universe, we ask are we the only technological species that ever arose?" Sullivan said. "This change eliminates the issue of the uncertainty of the question of the longevity of a civilization and allows us to address what we call the 'cosmic archaeological question' - how many times in the history of the universe has advanced life developed"?
This still leaves a huge uncertainty in calculating the chance of advanced life developing on a habitable planet. Instead of guessing the odds of developing advanced life, Frank and Sullivan calculated the odds against it, i.e. the factors that would make humanity the only advanced civilization in the entire history of the observable universe. The two calculated the dividing line between a universe where humanity is the only experiment in civilization and a universe where other species preceded us.
"Of course, we have no idea what the likelihood is that an intelligent technological species will develop on a habitable planet," says Frank. But with our method we can say exactly how low the probability is that we will be the only civilization the universe has created. We call this chance - the pessimistic line. If the actual probability exceeds the pessimistic line, then it is likely that a technological species has developed before us."
Using this approach, Frank and Sullivan calculated the probability that there had never been another example among the twenty billion trillion stars in the universe, or even among the hundred billion stars in our galaxy, the Milky Way.
The result? Frank and Sullivan discovered that the chance of human civilization being unique only if the chance of a civilization developing on a habitable planet is less than 1 in 10 million trillion or 1 part 10 to the 22nd power.
"One out of every 10 billion trillion is a very small number," says Frank. "For me, it suggests that it is likely that other intelligent beings evolved before us. Before our result, you would have been considered a pessimist if you imagined that the probability of a civilization developing on a habitable planet was, say, one in a million. But even this is a guess, a chance of one in a trillion, implies that what happened here on Earth with the development of humanity actually happened 10 billion other times in cosmic history."
For milk, the odds against the development of civilizations are 1 in 60 billion (if only because of the only known example), but if these numbers give ammunition to the optimists about the existence of alien civilizations, Sullivan points out that the complete Drake equation - with which you can estimate the chances of the existence of civilizations others, may give comfort to the pessimists.
"The universe is more than 13 billion years old," Sullivan said. "In other words, even if a thousand civilizations were created in our galaxy, if they only live for about ten thousand years, then they probably all died out and others did not develop technologically until recently like us, so that in order to have the chance of successfully discovering a contemporary active technological intelligence, the lifespan of a technologically intelligent civilization must be long Much more than with us so far."
"Given the vast distances between the stars and the constant speed of light we wouldn't be able to hold a conversation with another civilization anyway," Frank said. "If they are 50,000 light years away from us then the answer to each message will take 100 years to arrive."
But, as Frank and Sullivan point out, even if there are no other civilizations in our galaxy to communicate with our society, the new result still has profound scientific and philosophical importance. "From a basic point of view, the question is 'Did intelligent life ever form and develop before us? And it's amazing to assume that we're not the only ones."
According to Frank and Sullivan their conclusion also has a practical application. As humanity faces its own global climate change crisis, we can wonder if intelligent species of civilizations on another planet have passed a similar bottleneck and crossed over to the other side. As Frank put it, "We don't even know if it's possible for a high-tech civilization to last more than a few hundred years."
"Our results suggest that our biological evolution and culture were not unique and probably occurred many times in the past. There must have been times when cultures that were intensive consumers of energy faced similar crises and survived, this means we can start to explore the problem through simulations to get a sense of what leads to long-lived cultures and what not. "
25 תגובות
Those who think that we are alone also think that the State of Israel is the center of the world...
Published (one comment before Nissim's)
My response has been delayed for almost two hours.
Raphael
I get what you're saying.
What you said about the oxygen is interesting. A researcher named James Leblock said at the time that life on other planets could be discovered by an imbalance in the materials on the planet. The idea was revolutionary at the time and they did not listen to him - he claimed that as soon as there is life on the planet then the creatures will multiply until they reach a lack of a certain substance that exists in nature.
Raphael,
1. I answered your question: "Why are we looking for planets with conditions similar to Earth", the answer is of course because we know for sure that under such conditions life can exist, and as Nissim added there it is also much easier for us to identify them.
2. Simple logic (at least in my opinion) You enter a huge bakery the size of a continent, where tens of billions of shelves are loaded with loaves of bread, buns, challah, baguettes... You happen to approach one of the shelves and among the various pastries you suddenly notice a small spot of mold on one of the pastries.
What do you think the chances are that this is the only spot of mold in this entire huge bakery, and that there is not another spot of mold on any other loaf of bread or bun?
(I hope humanity will forgive me for this comparison)
Miracles
And by the way, there is just now another article in science where it is claimed that the earth had a large amount of oxygen before life began on it. So the existence of oxygen is not an indication of the existence of life.
A rival and miracles
There is a big difference between a chance for life to form and a chance for life to exist. If you don't know how life was created then you also don't know how to calculate the chance of its creation even if it is an infinite universe.
Out of the box,
Are you here? Answer if you read.
Very true, this is also an important point.
Raphael
Beyond what Shiriv wrote, there is another important consideration. We know how to recognize, on a planet like ours, life like ours. For example - if we see a high concentration of oxygen then we will almost certainly know that there is life there.
We will not know at all what to look for on planets with very different conditions.
Fix -
When budgets are tight, where should you invest your efforts? In the infinite places in the universe where it is not at all clear to us if life can exist in them? Or in a much smaller number of places where we know for sure that life can exist?
Raphael,
"I don't understand why they are looking for planets with similar conditions to Earth and based on what..."
I think it's a simple matter of logic, in our universe there is a huge space of conditions and possibilities in terms of temperatures, chemical compositions and the like, because this is where life was created, we know for sure that in this limited space of conditions life is possible. When budgets are tight, where should you invest your efforts? In the infinite places in the universe where it is not clear at all if life can exist in them? Or in a much smaller number of places where we know for sure that life can exist?
Miracles,
"It is hard to believe that we will ever know how life originated on Earth, or whether it even originated on Earth."
That's why I don't understand why they are looking for planets with similar conditions to Earth and based on what they calculate the chances of life being invented on them...
A. Ben Ner,
When I read a comment like yours, I never know whether to laugh or cry. After all, if an "outsider" were to write hypotheses as written in the article here, they would immediately attack him for writing nonsense (and this has already happened), but if scientists write hypotheses of this type - everything is fine because it is scientific. And if anything, then science is not a spoken language. I have never heard of abbreviations in formulations related to science. I have no idea why you are trying to justify what is written in the article, but at least don't preach - you understood what I read just fine, and also the scientific knowledge.
When we estimate the distances of stars..like for example if the article states a distance of 50,000 years then what we see or think we see may not exist..because what we see is a situation 50,000 years ago...hence the question and even if we send a message it may be a scan to a star that blew its breath tens of thousands ago years....right now at this stage it is better to concentrate on our neighborhood up to a distance of 20 to 40 light years...and maybe we might be able to reach humanity with an intelligence like ours or more...if it is not a shame to waste resources far away from us until the solution is found to move in space worms...it is better to invest in that and then Will it be possible to reach a solution, are we alone..
When we estimate the distances of stars..like for example if the article states a distance of 50,000 years then what we see or think we see may not exist..because what we see is a situation 50,000 years ago...hence the question and even if we send a message it may be a scan to a star that blew its breath tens of thousands ago years....right now at this stage it is better to concentrate on our neighborhood up to a distance of 20 to 40 light years...and maybe we might be able to reach humanity with an intelligence like ours or more...if it is not a shame to waste resources far away from us until the solution is found to move in space worms...it is better to invest in that and then Will it be possible to reach a solution, are we alone..
No. Ben Ner,
Your answer to Raphael is correct but not accurate. Today we know that liquid water also exists on the moons of the gas giants Jupiter and Saturn, the conditions on which cannot be defined as similar to the conditions on Earth, because they are far from the habitable zone around the Sun. The water on them is liquid as a result of gravitational tides, and there are probably oceans under the ice sheet around them.
If there is liquid water on these moons, there is also a hypothesis that they may be able to develop life on them, similar to the ecosystem found at the bottom of the oceans in the Earth, which are not fed by sunlight.
The reason we do not include such ecosystems in the calculations is because we do not know such ecosystems in action, but rather systems such as KDHA. We know which signs indicate DHA-like systems and not other systems.
my opinion -
It is very hard to believe that in this vast universe only here was created an "primitive soup" (I personally prefer chicken flavor) that allowed the development of life. Overall, in a macro view, the universe is quite homogeneous in terms of chemical composition, the distribution of gases, tens of billions of spiral galaxies similar to ours in every direction you look at it, stars, planets... it really seems logical to someone that "primitive soups" were not created Chemical and more or less similar conditions that allowed the formation of life in countless other places in the universe?
To me it sounds about the same as the chance that in all the years of the country's existence only once a person managed to win the first prize in the lottery even though hundreds of thousands try every week.
Raphael, but it is possible to formulate according to the article - a probability of how low the chance of life formation has to be in order for us to be the only ones in the universe ever. This is what the article is about and it is clearly written so it is not clear why you did not notice.
Raphael
It is hard to believe that we will ever know how life originated on Earth, or whether it even originated on Earth.
Today, we know how to produce both proteins and DNA in the laboratory, but we still do not know natural processes for each step. If we detect multiple processes, then we may not know which one is the one that happened in our case.
In response to Raphael:
Your claim is inaccurate. First, most life on Earth is exposed to the light and heat of the sun and exists thanks to solar energy. There are much rarer cases of life existing thanks to the heat energy emitted from the depths of the Earth, however, this life, which exists in the depths of the sea, is only possible thanks to the existence of liquid water on the surface of the Earth, and this is only possible thanks to the conditions that exist on the Earth.
In response to Bat El:
A]. You don't need to get too caught up in a slightly imprecise wording.
It is better to understand the concept. You must understand that mathematically precise wording often involves long and complex sentences that make it difficult, both in understanding the general idea, and in that they make the article long and difficult to read. Therefore, the general formulation is a necessity, especially in a popular article that is not professional science.
For the sake of clarification, I will demonstrate what I just claimed about the sentence that contradicted your claim:
"We have known for a long time how many stars there are in the universe"
This sentence can be written more precisely, which will meet your requirements as follows:
"We have known for a long time (to estimate, with an accuracy of about 20% +-) how many stars (visible today) there are in the universe (in the range we are able to observe today).
what happened here ? The sentence became precise in its wording but lengthened from 9 words to 22. And this, without contributing anything to the understanding of the idea.
B]. Regarding your claim that the article is "science fiction".
You probably didn't understand the basic idea of the article, which is an attempt to estimate the chances, on a statistical basis (!), for the existence of intelligent life on extrasolar planets.
There is no determination here, but an assessment of chances.
and finally a principled note,
Every scientific study starts with a hypothesis. And every hypothesis is fictional to some extent.
Furthermore, no scientific theory is 100% certain. Any theory may one day be proven wrong.
Therefore: all "science" is "science fiction".
Raphael,
It is never too late to ask the important questions of humanity. While it won't change your coffee in the morning, and it won't help you solve the problems at work tomorrow, but if we thought that way, you wouldn't be able to enjoy YouTube movies, a word processor at work, and navigation software on your mobile, because they all basically started from technologies that wouldn't exist if we hadn't asked. the "big questions" in science.
Although I agree with you and so does the article, that there are data that we still do not understand at this point in time, but you can consider the whole experience as a road map spring that points us in the right direction. For example, you will agree with me that we can all agree that there is no point in looking for life in the time before the formation of the universe, so we can set a certain limit for the formation of life even if we do not know for sure how it is formed.
"We have known for a long time how many stars there are in the universe" just this sentence alone indicates the reason why this article should be thrown in the trash can. And if that's not enough - continuing to read adds more insights that have nothing to do with science, but science fiction movies. So it's true that scientists are allowed to have fun with science fiction, but that's also how they should present their fun, without wrapping it in a scientific veil.
Fascinating article!
As long as they haven't definitely found the reason for the formation of life (not talking about evolution) then all these calculations are just blah blah.
Another note - the search for a way to go if conditions are similar to those of the Earth and identifications as those on which the chance of life developing is higher is simply illegitimate. There is life on Earth in places that have never seen the sun, at extremely high or low temperatures, without oxygen. In short, it's a shame.