"Milky Way Home to Billions of Free-Floating Life-Bearing Planets" --Originated in Early Universe

 

            

A few hundred thousand billion free-floating life-bearing Earth-sized planets may exist in the space between stars in the Milky Way. So argues an international team of scientists led by Chandra Wickramasinghe, Director of the Buckingham Center for Astrobiology at the University of Buckingham, UK. The scientists have proposed that these life-bearing planets originated in the early Universe within a few million years of the Big Bang, and that they make up most of the so-called “missing mass” of galaxies.

The team calculated that such a planetary body would cross the inner solar system every 25 million years on the average and during each transit, zodiacal dust, including a component of the solar system’s living cells, becomes implanted at its surface. The free-floating planets would then have the added property of mixing the products of local biological evolution on a galaxy-wide scale.

Since 1995, when the first extrasolar planet was reported, interest in searching for planets has reached a feverish pitch. The 750 or so detections of exoplanets are all of planets orbiting stars, and very few, if any, have been deemed potential candidates for life. The possibility of a much larger number of planets was first suggested in earlier studies where the effects of gravitational lensing of distant quasars by intervening planet-sized bodies were measured. 

Recently several groups of investigators have suggested that a few billion such objects could exist in the galaxy. Wickramasinghe and team have increased this grand total of planets to a few hundred thousand billion (a few thousand for every Milky Way star) - each one harbouring the legacy of cosmic primordial life.

Are we the lone sentient life in the universe? So far, we have no evidence to the contrary, and yet the odds that not one single other planet has evolved intelligent life would appear, from a statistical standpoint, to be quite small. There are an estimated 250 billion (2.5 x 10¹¹ ) stars in the Milky Way alone, and over 70 sextillion (7 x 10²² ) in the visible universe, and many of them are surrounded by multiple planets.

Meanwhile, our 4.5 billion-year old Solar System exits in a universe that is estimated to be between 13.5 and 14 billion years old. Some experts believe that there could be advanced civilizations out there that have existed for 1.8 gigayears (one gigayear = one billion years).

The odds of there being only one single planet that evolved life among all that unfathomable vastness seems so incredible that it is all but completely irrational to believe. But then "where are they?" asked physicist Enrico Fermi while having lunch with his colleagues in 1950.

Fermi reasoned, if there are other advanced extraterrestrial civilizations, then why is there no evidence of such, like spacecraft or probes floating around the Milky Way. His question became famously known as the Fermi Paradox. The paradox is the contradiction between the high estimates of the probability of the existence of extraterrestrial civilizations and yet the lack of evidence for, or contact with, any such civilizations.

Given the extreme age of the universe, and its vast number of stars, if planets like Earth are at all typical, then there should be many advanced extraterrestrial civilizations out there, and at least a few in our own Milky Way. Another closely related question is the Great Silence, which poses the question: Even if space travel is too difficult, if life is out there, why don't we at least detect some sign of civilization like radio transmissions?

Milan Cirkovic of the Astronomical Observatory in Belgrade, points out that the median age of terrestrial planets in the Milky Way is about 1.8 gigayears greater than the age of the Earth and the Solar System, which means that the median age of technological civilizations should be greater than the age of human civilization by the same amount. The vastness of this interval indicates that one or more processes must suppress observability of extraterrestrial communities.

Cirkovic believes that highly efficient city-state type of advanced technological civilizations could easily pass unnoticed even by much more advanced SETI equipment, especially if located near the Milky Way rim or other remote locations.

Spurce: Wickramasinghe NC et al (2012). Life-bearing primordial planets in the solar vicinity. Astrophysics and Space Science; DOI 10.1007/s10509-012-1092-8

The Daily Galaxy via Springer journal Astrophysics and Space Science

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Comments

[Psy]

They are talking about planets *not* orbiting stars having life.

Awfully cold for that, unless I am missing something...

[Velocity_Wave]

@Psy:
Interesting question since interstellar space is indeed very cold!

And yet some believe that rogue planets, which wander freely between solar systems could indeed still have life, despite the cold conditions.

For example:

if you had a rogue Jupiter sized planet with many moons orbiting, you could have a moon that has a vast liquid water ocean, covered by ice, just like we have in our solar system: Europa, or Enceladus.

Europa/Enceladus style liquid oceans are not heated by the sun, but rather through gravitational flexing as they orbit a bigger planet.

So that gravitational based heat source would continue, even if Jupiter was wandering aimlessly through the galaxy. Life would still have a warm place to live.

And then one day, millions or billions of years in the future, that rogue version of Jupiter could plow it's way through another solar system by pure chance.

As it plowed through, asteroids from that other solar system could get disturbed and impact the liquid ocean moon Europa, ejecting lots of water and "bacteria" (assuming Europa has life). That bacteria could then seed planets and moons in that other solar system.

At the same time, if that other solar system had life, then some of it's "bacteria" could likewise get deposited.

Same thing with an Earth sized rogue planet.

If Earth was suddenly thrust out of our solar system, into deep space, life would still survive, probably for many (many) billions of years, as Earth wandered aimlessly in deep cold between the stars.

For example, bacteria has been found 6 to 7 miles underground on Earth. So that bacteria would likely survive and continue along its ultra slow path of evolution.

Earths oceans would become frozen solid... but even then there would probably be a considerable amount of bacterial life that would still survive in the frozen ice... very slow moving, slow life cycle bacteria.

And then one day, if that frozen Earth plowed through another solar system, meteors from that solar system would impact the frozen oceans, and throw Earth water with Earth bacteria into the region of that new solar system.

That Earth bacteria could then "seed" planets in that new solar system...

And of course Earth could pick up samples of "alien bacteria" as well...

[Bob Greenwade]

First, kudos to whomever formatted this article; we actually get to see real superscripts, and not just straight four-digit numbers (going beyond even using the carat symbol). This has been an issue on this site for a while, and it's a very welcome sight.

On the other hand, the article's topic does kind of wander from the main topic of life on rogue planets over to a discussion of the Fermi paradox, about the possibility of us being the only sentient [sic] life in the universe.

Thought it's only four paragraphs long, I find the stuff about life on rogue planets quite thought-provoking. The article could have stood at just those four paragraphs, and been absolutely fine.

VW's expansion of the thought is particularly interesting, and brings more ideas to my mind than I really have the time and energy for right now.

Then the question, "Are we the lone sentient life in the universe?" That's a complete non-sequitur; that and everything that follows would be worthwhile in another article, if there was anything new to add (or if it was put into a "Classic" or other special kind of category). Had it been a separate article, I'd share some thoughts on what's said here, but those thoughts have nothing to do with life on rogue planets so I'll let it wait.

[resonanz]

As with B.Greenwade, the superscripts are much appreciated. But, there is disagreement re, to me, the logical follow-thru introductions of the Fermi Paradox and ponderings on Life in the Universe. Seems that the search for Life is perhaps the main driving factor in our space programs today, maybe always?

[Kennedy]

I believe the answer is in the article. If there are indeed a few thousand roaming planets per star, then we're are they going? They would be drawn towards the gravity of a nearby star whist on their paths. 
If other stars are like ours with a kuiper belt & Oort cloud, then the passing of a planet sized body - even if it just went close by - would be a major disruption to any stability. The inner planets would be bombarded by thousands of comets and asteroids. 250 million years ago we ourselves had the late bombardment and no one knows why. 
Life could be very wide spread on planets though out the universe, but like dinosaurs, it gets wiped out before it can develop. Maybe we have just been lucky so far. Maybe there are even a few more civilizations out there, but they are separated by such vast distances that we may never even know that they are there..
The universe is using planets as its weed wacker.

[Ky]

"..and that they make up most of the so-called “missing mass” of galaxies."

I wanted the article to explore this claim in further depth. Are they saying that Dark Matter could actually be rogue planets?

[Mark D]

Typical of this blog and not a bad thing... is that this is a stimulating mind-game... one combining missing-mass-of-Milky Way issues with life-bearing exosolar planets and sentient, evolved being in billion year old civilizations. Quite a hotch-potch of stuff.

Prof' Hawking, I am told, in answer to the last, might have suggested that asteroid-strilke, so common in the solar system might just as likely disrupt the periodicty of any evolutionary process on any other planet with ecosystems and biodiversity. Our last and most devastating strike perhaps 70 million years ago... was only one of many potentially life ending events. Perhaps it is impossible to imagine the conditions under which a civilization could evolve for even 100,000 years much less a million or billion.

[Matthew]

That would assume that all solar system have asteroid belts or rogue debris floating threw them. That is a pretty stupid assumption considering we haven't even been able to explore our own solar system in detail, let alone our galaxy. We need to stop making assumptions about the nature of the universe and let it teach us what is real and what is just theory.

[Mark D]

So Matthew, do you feel this way about the extraordinarily strange assumptions that underly this article about 'rogue' planets somehow also being able to support life.

I think Hawking's surmise is no less sensible than the earliest assumptions that led us to finally look for and prove that exosolar planets actually do exist and in great number.

[Matthew]

We'll i personally think that simple forms of life (microbial) are probably abundant throughout the universe. So no i don't think the assumption that it may even survive on a rogue planet is too far reaching given the evidence that microbial life can form and survive in pretty much any environment, including asteroids and comets. I guess i wouldn't call his theory stupid after thinking about it more, that man has more intelligence in his toe jam than i have altogether. I just have a problem with using only our own solar system's history as a cosmic barometer for any theories really. I think the universe is full of so many variables and possibilities that to even put forth a theory towards questions that big, are bound to be proven wrong.

[Matthew]

After all complex life has been wiped out on this planet at least once before, and yet it survived and evolved anyways into us and all the creatures of Earth. It really is a question to big to answer.

[mike]

Huge question yes but without a theory how can you begin to find answers it is through forming theories then testing these theories that we may gain greater understanding whether the theory holds true or is debunked it is still teaching us something and moving us toward our next theory and more understanding