April 17, 2024

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Life spreads through space on tiny, invisible particles, study suggests: ScienceAlert

Life spreads through space on tiny, invisible particles, study suggests: ScienceAlert

Does life appear independently on different planets in the galaxy? Or does it move from one world to another? Or does it do both?

New research shows how life could spread via a basic, simple path: cosmic dust.

One thing scientists have learned in the past few decades is that life on Earth may have had an early beginning.

The Earth is about 4.53 billion years old, and some evidence suggests that simple life has been here for at least 3.5 billion years. Some evidence suggests that life was here even earlier, only about 500 million years after the Earth formed when it cooled. Life was so simple, but it might have been there.

But life may not have originated here. Researchers wonder whether there was enough time for life to spontaneously emerge in early Earth conditions.

New research examines the idea that cosmic dust could be responsible for spreading life throughout the galaxy Panspermia. Life arose elsewhere and was delivered to the young Earth. This is not a new idea, but in this work, the author calculates how quickly this could happen.

Artistic rendering of Earth in the Early Archean period with a purple hydrosphere and coastal areas. Even in this early period, life flourished and gained complexity. (Oleg Kuznetsov)

Search titled “The possibility of the existence of panspermia in the depths of the universe through planetary dust grains“The sole author is ZN Osmanov, from the Faculty of Physics at Tbilisi Free University in Georgia. The paper is in pre-print and has not yet been published.

No matter how much we contemplate and research the origins of life, we do not know how it began. We have an idea of ​​what kind of environment it could produce, but even that idea has been obscured for billions of years.

“The main problem is clearly the origin of life or abiogenesis, the details of which are still unknown to us,” Usmanov writes.

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But it started somehow. Regardless of life's original appearance, for now, Usmanov turns to how it spreads.

“By assuming that planetary dust particles can escape the planet’s gravity, we consider the possibility that dust grains escape from the star system via radiation pressure,” Usmanov wrote.

The idea that life itself could travel through space on comets and asteroids is familiar to many people. When these objects collide with planets, thinking continues, mobile life is provided, and if there is a place that can be exploited, it will happen. But how can simple dust achieve the same thing?

This concept art shows large asteroids that penetrated Earth's early atmosphere.  Photography: SwRI/Dan Durda/Simon Marchi
This concept art shows large asteroids that penetrated Earth's early atmosphere. (SwRI/Dan Durda/Simon Marchi)

For dust to carry life, it must originate from a planet that hosts life. This can happen in specific circumstances. Research shows that dust particles coming from Earth and present in the planet's high atmosphere can scatter against cosmic dust grains.

a Paper 2017 In the magazine Astrobiology Show how ultrafast space dust can interact with Earth dust, creating powerful momentum flows. A small fraction of planetary dust particles can be accelerated enough to escape the planet's gravity.

Once the dust is freed from its planet's gravity, it is at the mercy of stellar radiation pressure.

“If a similar scenario occurs in other systems, planetary dust particles, which are already free from the planet's gravitational field, may escape from the star system via radiation pressure and initial velocity, spreading life into the universe,” explains Usmanov. .

Life must be very durable to survive on a grain of dust as it travels through interstellar space. You should avoid hazards such as radiation and heat. If life itself can't do it, perhaps the complex molecules that give rise to life can. If we accept that this is possible, the next question is how quickly it will spread.

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“It has been shown that in 5 billion years, dust grains will reach 105 “Stellar systems, and by taking the Drake equation into account, it turns out that the entire galaxy would be full of planetary dust particles,” Usmanov explains.

Usmanov points to other research on mass seeding and how it could happen in our galactic neighborhood.

“In particular, it has been pointed out that through solar radiation pressure, small dust grains containing living organisms could travel to the nearest solar system, Alpha Centauri, within nine thousand years,” Usmanov writes. Our powerful rockets, like the Space Launch System and Falcon Heavy, will take more than 100,000 years to make the journey.

Panspermia is the idea that life is spread throughout the galaxy, or even the universe, by dust, asteroids, comets, and even minor planets.  Image credit: NASA/GenieMotor
Panspermia is the idea that life is spread throughout the galaxy, or even the universe, by dust, asteroids, comets, and even minor planets. (NASA/GenieMotor)

It's an interesting idea. Usmanov estimates that a large number of dust grains would survive in interstellar space with life or complex molecules intact. But his thinking hits a bit of a speed bump at one point.

He takes a bold step beyond our current knowledge when he writes: “On the other hand, it is natural to assume that the number of planets with at least primitive life must be enormous.” This may be a natural assumption, but there is little evidence to support it. It's a guess, a motivated guess, but a guess nonetheless.

Working using a statistical approach to the Drake equation, Usmanov writes that the number of planets that have developed life is “on the order of 3 x 107“.

“This value is so huge that if dust particles can travel a distance of up to several hundred light-years, one can conclude that the MW, with a diameter of 100,000 light-years, must be filled with complex particles distributed throughout the entire galaxy.” Usmanov explains. “Even if we assume that life was destroyed during this time, the vast majority of complex molecules would remain intact.”

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Standing next to the Milky Way.  If Usmanov is right, the entire galaxy is filled with planetary dust.  Credit: P. Horálek/ESO
Standing next to the Milky Way. If Usmanov is right, the entire galaxy is filled with planetary dust. (B. Horalik/ESO)

It's very interesting work. But the frustrating thing about this whole thing is that we still don't know how life appears or how often it appears. So, all our thought experiments and calculations, including Usmanov's, have a solid mass of unknowns at the center.

If we are lucky to find solid evidence of life on Mars, for example, this kind of research and the conversations it generates will take on a new luster. But for now, Usmanov's work and similar work by other researchers leaves us in a funny position: We can only imagine and calculate how life could spread, to what extent, and at what speed.

Usmanov claims that the number of planets with primitive life is enormous. We don't know that. Planets are very complex, and there are a surprising number of variables. Even if there were a huge number of planets with primitive life, many of them would be larger than Earth's mass. For example, would life-bearing dust particles or complex organic molecules be able to escape the grip of Earth's supergravity?

This research shows how life, or at least its basic units, can escape planets and survive the interstellar journey to another world. If this is true, and panspermia can explain the appearance of life on Earth shortly after it formed and cooled, it changes our understanding of our origins and even of the rest of the universe.

But we don't know how true it is, and we still don't know how it started.

This article was originally published by The universe today. Read the Original article.