Is Alien Life hiding beyond Earth 2.0?

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When we think of life in the Universe, far beyond the limits of the Earth, we can not help but look at our own planet as a guide. The Earth has a number of characteristics that we believe are extremely important – perhaps even essential – for life to flourish and thrive. For generations, humans have dreamed of a life beyond the Earth, striving to find another world similar to ours, but with its own success story: our own Earth 2.0.

But the fact that life has succeeded here on Earth does not necessarily mean that life will probably succeed in earth-like worlds, but only that it will be possible. Likewise, the fact that life was not found on non-terrestrial worlds does not mean that it is not possible. In fact, it is quite possible that the most common life forms in the galaxy are very different from terrestrial life forms and occur more frequently in worlds different from ours. The only way to know is to watch, and this requires looking for signals of observation that could lead us to rethink our place in the universe.

We have the right mixture of light and heavy elements to create a rocky planet with a thin but substantial atmosphere and the basic ingredients for life. We orbit a star at the right distance for liquid water on our surface, our planet having both oceans and continents. Our sun has lived long enough (and not enough in mass) for life to evolve and become complex, differentiated and perhaps intelligent, but sufficiently high in mass so that the outbreaks are not so numerous as they do. to disappear our atmosphere. .

Our planet turns on itself, but it is not locked, so we have days and nights all year long. We have a big moon to stabilize our axial inclination. We have a big world (Jupiter) outside our jelly line to protect the inner planets from catastrophic strikes. When we think about it in this way, looking for a world similar to Earth's – a proverbial "Earth 2.0" – seems to be obvious.

There are many reasons to believe that looking for a world as Earth-like as possible, around a star as similar to the Sun as possible, could be the best place to look for life elsewhere. in the Universe. We know that it is very likely that billions of solar systems have at least similar properties to the Earth and the Sun, thanks to the tremendous progress made in studies of exoplanets over the last three decades.

Since life has not only arisen, but has become complex, differentiated, intelligent and technologically advanced here on Earth, it makes sense to choose worlds similar to those of the Earth in our quest for a world inhabited in the galaxy. Certainly, if this happens here under the conditions we ourselves have, it must be possible for life to come back, elsewhere, under similar conditions.

Virtually no one in exoplanet or astrobiological communities thinks looking for worlds similar to a proverbial "Earth 2.0" is a bad idea. But is it the smartest way to invest the overwhelming majority of our resources in researching and investigating worlds with similarities to our own planet, rich in lives? I had the opportunity to sit down and record a podcast with scientist Adrian Lenardic, who does not agree with this position at all.

If science has taught us anything, it is that we should not assume that we know the answer before making key experiments or making critical observations. Yes, we must look for evidence, but also in places where we might think that life is unlikely to develop, develop, or sustain itself. The Universe is full of surprises, and if we do not give ourselves the opportunity to let the Universe surprise us, we will draw biased and therefore fundamentally unscientific conclusions.

Our preconceived ideas about the functioning of life were wrong before, because what we thought to be the necessary restrictions turned out to be circumvented not only abundantly, but perhaps easily and frequently.

For example, it was once thought that life required sunlight. But the discovery of life around the hydrothermal vents several kilometers below the surface of the ocean has taught us that even in the absolute absence of sunlight, life can find a way.

We once thought that life could not survive in an environment rich in arsenic, arsenic being a known poison of biological systems. Yet, not only recent discoveries have shown that life is possible in regions rich in arsenic, but that arsenic can even be used in biological processes.

And perhaps most surprisingly, we thought that the complex life could never survive in the hostile environment of space. But the tardigrade has proved the opposite, entering a state of animation suspended in the void of space and rehydrating successfully when it is sent back to Earth.

This should lead you to wonder what else could happen. Could there be life in the underground oceans of Moon Europe Jupiter, Saturn's Enceladus, Neptune's Triton or even Pluto, cold and distant? They are all orbiting large, massive worlds (Charon Pluto's accounts), which exert tidal forces on the inside of the planet, providing a source of heat and energy, even in a environment where no sunlight can penetrate.

On rocky worlds without sufficient atmosphere to hold liquid water, an underwater ocean is always possible. Mars, for example, could have abundant amounts of liquid groundwater below the surface, thus providing a possible environment for life. Even a totally uninhabitable environment like Venus could have life, because the region above the clouds, about sixty kilometers away, has temperatures and atmospheric pressure similar to those of the Earth.

Of course, we could look at the most widespread star class in the universe – red dwarf stars (class M), which account for 75-80% of all stars – and find all kinds of reasons why life is unlikely to exist there. Here are a few:

• Class M stars lock all Earth-sized (rocky) planets anywhere liquid water is able to form on very short time scales (~ 1 million years or less).
• Class M stars blaze ubiquitously and easily remove an Earth-like atmosphere for short periods of time.
• The X-rays emitted by these stars are too big and too numerous and would irradiate the planet enough to make life as we know it untenable.
• And that the lack of high energy light (ultraviolet and yellow / green / blue / purple) would make photosynthesis impossible, thus preventing primitive life from being born.

If these are your reasons for disfavoring life around the most common star class in the Universe, where about 6% of these stars would have Earth-sized planets in what we call the habitable zone (to the right distance for a world with Earth-like conditions to have liquid water on its surface), you will need to reconsider your assumptions.

Tidal foreclosure may not be as severe as we thought, as magnetic fields and substantial atmospheres with high winds could still alter energy input. A planet (like Venus) that constantly generates new atmospheric particles could potentially survive solar wind streaking / eruption phenomena. The organisms can dive to deeper depths during x-rays, shielding themselves from radiation. And photosynthesis, like all life processes on Earth, relies solely on the use of 20 amino acids, but it is known that more than 60 additional acids occur naturally throughout the universe.

Although we have every reason to believe that life can be ubiquitous – or at least have a chance "- on very similar worlds to the Earth, it is also very plausible that life is more abundant on worlds that do not resemble not us.

Perhaps the exomoons orbiting large planets (with significant tidal forces) are even more conducive to the original life than a world like Earth.

Liquid water on the planet itself may not be essential for life, because the type of cell wall or membrane that is appropriate can allow water to exist in an aqueous state.

Perhaps radioisotope disintegration, geothermal sources or even chemical sources of energy could provide life with the external source it needs; maybe rogue planets – without parental stars at all – could harbor extraterrestrial life.

Even super-Earths, perhaps more numerous than earth-sized worlds, could potentially be habitable under the right circumstances. What is wonderful about this idea is that it is as easily testable as a Earth-like world around a Sun-like star. To examine a planet looking for clues of life, we can tackle this puzzle with many avenues for investigation. We can:

• wait for a planetary transit and try to perform spectroscopy on absorbed light, by probing the contents of an exo-atmosphere,
• we can try to solve the world itself with direct imagery, looking for seasonal variations and signs such as the periodic greening of the world,
• or we can search for nuclear, neutrino or technical signatures that could indicate the presence of a planet manipulated by its inhabitants, whether intelligent or not.

It may be that life is rare in the Universe, in which case we will need to look at many candidate planets – perhaps with great precision – to reveal a successful detection. But if we search exclusively for planets with properties similar to the Earth and limit ourselves to examining mother stars and solar systems that are similar to ours, we are condemned to obtain a biased representation of what exists.

You might think, in the quest for extraterrestrial life, that more, that is more, and that the best way to find life beyond Earth is to examine a larger number of candidate planets. which could be the 2.0 Earth we've been dreaming of for so long. . But planets not resembling the Earth could shelter a life that we had never envisioned and that we will not know unless we look at it. More is more, but "different" is also more. As scientists, we must be careful not to skew our results even before we have really begun to look.

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When we think of life in the Universe, far beyond the limits of the Earth, we can not help but look at our own planet as a guide. The Earth has a number of features that we believe are extremely important, if not essential, for life to flourish and thrive. For generations, humans have dreamed of a life beyond Earth, striving to find another world similar to ours, but with its own success story: our own Earth 2.0.

But the fact that life has succeeded here on Earth does not necessarily mean that life will probably succeed in earth-like worlds, but only that it will be possible. Likewise, the fact that life was not found on non-terrestrial worlds does not mean that it is not possible. In fact, it is quite possible that the most common life forms in the galaxy are very different from terrestrial life forms and occur more frequently in worlds different from ours. The only way to know is to watch, and this requires looking for signals of observation that could lead us to rethink our place in the universe.

We have the right mixture of light and heavy elements to create a rocky planet with a thin but substantial atmosphere and the basic ingredients for life. We orbit a star at the right distance for liquid water on our surface, our planet having both oceans and continents. Our sun has lived long enough (and not enough in mass) for life to evolve and become complex, differentiated and perhaps intelligent, but sufficiently high in mass so that the outbreaks are not so numerous as they do. to disappear our atmosphere. .

Our planet turns on itself, but it is not locked, so we have days and nights all year long. We have a big moon to stabilize our axial inclination. We have a big world (Jupiter) outside our jelly line to protect the inner planets from catastrophic strikes. When we think about it in this way, the search for a world similar to Earth's – a proverbial "Earth 2.0" – seems to be obvious.

There are many reasons to believe that looking for a world as Earth-like as possible, around a star as similar to the Sun as possible, could be the best place to look for life elsewhere. in the Universe. We know that it is very likely that billions of solar systems have at least similar properties to the Earth and the Sun, thanks to the tremendous progress made in studies of exoplanets over the last three decades.

Since life has not only arisen, but has become complex, differentiated, intelligent and technologically advanced here on Earth, it makes sense to choose worlds similar to those of the Earth in our quest for a world inhabited in the galaxy. Certainly, if this happens here under the conditions we ourselves have, it must be possible for life to come back, elsewhere, under similar conditions.

Virtually no one in exoplanet or astrobiological communities thinks looking for worlds similar to a proverbial "Earth 2.0" is a bad idea. But is it the smartest way to invest the overwhelming majority of our resources in researching and investigating worlds with similarities to our own planet, rich in lives? I've had the opportunity to sit down and record a podcast with scientist Adrian Lenardic, who does not agree with this position at all.

If science has taught us anything, it is that we should not assume that we know the answer before making key experiments or making critical observations. Yes, we must look for evidence, but also in places where we might think that life is unlikely to develop, develop, or sustain itself. The Universe is full of surprises and if we do not give ourselves the opportunity to let the Universe surprise us, we will draw biased conclusions – and therefore fundamentally unscientific.

Our preconceived ideas about the functioning of life were wrong before, because what we thought to be the necessary restrictions turned out to be circumvented not only abundantly, but perhaps easily and frequently.

For example, it was once thought that life required sunlight. But the discovery of life around the hydrothermal vents several kilometers below the surface of the ocean has taught us that even in the absolute absence of sunlight, life can find a way.

We once thought that life could not survive in an environment rich in arsenic, arsenic being a known poison of biological systems. Yet, not only recent discoveries have shown that life is possible in regions rich in arsenic, but that arsenic can even be used in biological processes.

And perhaps most surprisingly, we thought that the complex life could never survive in the hostile environment of space. But the tardigrade has proved the opposite, entering a state of animation suspended in the void of space and rehydrating successfully when it is sent back to Earth.

This should lead you to wonder what else could happen. Could there be life in the underground oceans of Moon Europe Jupiter, Saturn's Enceladus, Neptune's Triton or even Pluto, cold and distant? They are all orbiting large, massive worlds (Charon Pluto's accounts), which exert tidal forces on the inside of the planet, providing a source of heat and energy, even in a environment where no sunlight can penetrate.

On rocky worlds without sufficient atmosphere to hold liquid water, an underwater ocean is always possible. Mars, for example, could have abundant amounts of liquid groundwater below the surface, thus providing a possible environment for life. Even a totally uninhabitable environment like Venus could have life, because the region above the clouds, about sixty kilometers away, has temperatures and atmospheric pressure similar to those of the Earth.

Of course, we could look at the most widespread star class in the Universe – red dwarf stars (M-class), which account for 75-80% of all stars – and find all kinds of reasons why life is unlikely. to exist there. Here are a few:

• Class M stars lock all Earth-sized (rocky) planets anywhere liquid water is able to form on very short time scales (~ 1 million years or less).
• Class M stars blaze ubiquitously and easily remove an Earth-like atmosphere for short periods of time.
• The X-rays emitted by these stars are too big and too numerous and would irradiate the planet enough to make life as we know it untenable.
• And that the lack of high energy light (ultraviolet and yellow / green / blue / purple) would make photosynthesis impossible, thus preventing primitive life from being born.

If these are your reasons for disfavoring life around the most common star class in the Universe, where about 6% of these stars would have Earth-sized planets in what we call the habitable zone (to the right distance for a world with Earth-like conditions to have liquid water on its surface), you will need to reconsider your assumptions.

Tidal foreclosure may not be as severe as we thought, as magnetic fields and substantial atmospheres with high winds could still alter energy input. A planet (like Venus) that constantly generates new atmospheric particles could potentially survive solar wind streaking / eruption phenomena. The organisms can dive to deeper depths during x-rays, shielding themselves from radiation. And photosynthesis, like all life processes on Earth, relies solely on the use of 20 amino acids, but it is known that more than 60 additional acids occur naturally throughout the universe.

Bien que nous ayons toutes les raisons de croire que la vie peut être omniprésente – ou du moins avoir une chance – sur des mondes très similaires à la Terre, il est également très plausible que la vie soit plus abondante sur des mondes qui ne ressemblent pas au nôtre.

Peut-être que les exomoons en orbite autour de grandes planètes (avec d&#39;importantes forces de marée) sont encore plus propices à la vie originelle qu&#39;un monde comme la Terre.

L’eau liquide sur la planète elle-même n’est peut-être pas indispensable à la vie, car le type de paroi cellulaire ou de membrane approprié peut permettre à l’eau d’exister dans un état aqueux.

Peut-être que la désintégration radio-isotopique, les sources géothermiques ou même les sources d&#39;énergie chimiques pourraient assurer la vie avec la source externe dont elle a besoin; peut-être que des planètes voyous – sans étoiles parentales du tout – pourraient abriter une vie extraterrestre.

Même les super-Terre, peut-être plus nombreuses que les mondes de la taille de la Terre, pourraient être potentiellement habitables dans de bonnes circonstances. Ce qui est merveilleux avec cette idée, c’est qu’elle est testable aussi facilement qu’un monde semblable à la Terre autour d’une étoile semblable au Soleil. Pour examiner une planète à la recherche d&#39;indices de la vie, nous pouvons aborder ce casse-tête avec de nombreuses pistes d&#39;enquête. Nous pouvons:

• attendre un transit planétaire et essayer d&#39;effectuer une spectroscopie sur la lumière absorbée, en sondant le contenu d&#39;une exo-atmosphère,
• nous pouvons essayer de résoudre le monde lui-même avec une imagerie directe, en recherchant des variations saisonnières et des signes tels que le verdissement périodique du monde,
• ou bien nous pouvons rechercher des signatures nucléaires, neutrino ou techniques qui pourraient indiquer la présence d’une planète manipulée par ses habitants, qu’elle soit intelligente ou non.

Il se peut que la vie soit rare dans l’Univers, auquel cas nous aurons besoin de regarder beaucoup de planètes candidates – peut-être avec une très grande précision – pour révéler une détection réussie. Mais si nous recherchons exclusivement des planètes ayant des propriétés similaires à la Terre et que nous nous limitons à examiner les étoiles mères et les systèmes solaires qui sont similaires aux nôtres, nous sommes condamnés à obtenir une représentation biaisée de ce qui existe.

Vous pourriez penser, dans la recherche de la vie extraterrestre, que plus, c&#39;est plus, et que le meilleur moyen de trouver la vie au-delà de la Terre est d&#39;examiner un plus grand nombre de planètes candidates qui pourraient être la Terre 2.0 dont nous rêvons depuis si longtemps. . Mais des planètes ne ressemblant pas à la Terre pourraient abriter une vie que nous n&#39;avions jamais envisagée et que nous ne saurons pas à moins de regarder. Plus c&#39;est plus, mais "différent" c&#39;est aussi plus. En tant que scientifiques, nous devons faire attention à ne pas biaiser nos résultats avant même que nous ayons vraiment commencé à regarder.