Life on Earth....an unrepeatable accident?

Question

I have often thought that Earth is so unique, it harbours the only life in the universe! Everything had to be JUST right for life to first take a hold.

A denser atmosphere --> No life (Venus)
Too hot --> no life (Mercury)
Too little atmosphere --> No life (mars)
to name only three amazing co-incidences that have to be met.

So, do you believe Earth is the only life harbouring place in the universe? Is the odds of this accident happening again less than the number of stars with planets?

So far, we have not even found solid evidence of even a single celled form of life in the few places we have managed to explore and received no convincing signals from space (except the 'wow' signal SETI found but that could be natural).

Some of you misunderstand my intention of this question, the way I have worded it is poor.

I dont intend to say that I beleive we are the only life in the universe, but that I have often thought if we are due to the extraordinary conditions required (well, that is the life that we know needs).

Answer 1

We know that there is life on Earth but we have not made a serious search for it elsewhere. It's illogical to say that because there is life on Earth therefore it must be common elsewhere based on a survey with a sample size of one.
Your feeling that life on earth is unique may well be right but we simply don't know and the question requires much more study before we can even begin to answer it. Of course finding life on Mars or somewhere else answers the question one way. But if we look and look and still find nothing the question has to remain open because there will always be places we haven't looked.

Answer 2

There are some indications that life could exist elsewhere in the universe.

Two of the most emminent examples are:
1) Viruses/ bacteria that arrive on earth from space on metiorides.
2) Recent study of the moon Titan in our own solar system shows that mud there is very similar in composition to the "primordial soup" believed to have been the condition on Earth from which life sprung. Although the atmosphere on Titan could not currently support life as we know it, a relatively small temperature chancge could make it possible, as certain areas of the planet would undergo a thawing of some of the dense ice cloud. Life on Earth can exist at the very bottom of the oceans, where the effects of the sun are negligible, where hot geysers spew sulfurus lavae and the Earth's crust is being continuously recyclyed. Discoveries of life forms here suggest that, contrary to previus assertions, certain light and heat requirements are not essential for any life form!

Consequently, it is highly likely that life forms do exist elsewhere in the universe at present. We must also consider that life may have existed previously or may yet evolve as the climate and conditions at various points in the universe alter with its continuous expansion and cooling and as stars and suns move through their own life cycles.

Yes, the conditions required to support a life form simmilar to our own are quite specific and limit the number of places this is possible, however, our exploration of the universe thus far has revealed that the universe is made up of pretty much the same elements as we experience here - so the permeations are finite in an infinite ammount of time and space. The odds are in favour of life occurring elsewhere at some time.

As to whether this is an accident or part of a carefully measured plan of a satient superbeing, the jury is still out.

Answer 3

The conditions for life to exist on a planet are pretty specific and pretty extraordinary.

The odds against a solar system possessing all of the proper ingredients for life to get a foothold (planet at the right range from the sun - not too hot, not too cold; presence of liquid water; magnetic field to shield life from cosmic radiation; large enough world to hold gaseous molecules like oxygen, but not so large that gravity crushes growing life; etc.) are, well... astronomical.

However, when you consider the size of the universe, even astronomical odds become a statistical sure thing. Even if only one out of TEN BILLION star systems has all of the ingredients to harbour the development of life, that still means there could well be at least 10 systems in this galaxy alone that have life.

And the Hubble telescope has found that there may be 125 billion galaxies in the universe. If the same odds hold true for those galaxies, that means there are more than a TRILLION star systems in the universe that fit all of those criteria.

That's assuming that the chances of a solar system possessing life are one in ten billion. It could very well be much, much lower. We won't know for sure until we get some more data about other star systems and how likely it is they will have planets in their biozone and if they have the right environments for life to develop.

So even if the conditions are extremely rare, with the number of stars in the universe it's virtually impossible that there isn't life somewhere out there.

Of course, that life could well be some kind of alien bacteria, or perhaps only as advanced as insects or green algae. Perhaps the chances of a life bearing world developing a sentient race is only one in a trillion. In which case even with the number of stars in the universe we could be the only sentient race. We just don't have enough data to make proper odds yet.

Answer 4

Actually, evidence of life has been found on other planets. And the conditions on earth are (were) just right for CARBON based life like us. But say if there were Silicone based life or Ammonia based life the conditions required for that particular form of life would probably be drastically different from our requirements.

Many scientists have stated that the one necessity for all life is water. That may not be the case. I believe that with the size of the universe and the high numbers of galaxies with their billions of stars and planets that other life does exist out in the universe. The odds of Earth being the only planet with life are extremely low.

As a final note, many scientists refuse to look for evidence of life in the more chaotic parts of our galaxy. The only fact I can offer is this. The bounds of physics, chemisty, and biology have barely been scratched and the possibilites are limitless. Who knows what is out there in the universe?

Answer 5

Can I suggest you read about the Drake Equation which deals with the various factors that affect whether life can emerge or not, and about the opposite point of view the Rate Earth Hypothesis (not the same thing as "rare earths" in the Periodic Table).which argues life in the universe may not be as frequent as we would like to think.

This equation was devised by Dr. Frank Drake (a professor at the University of California, Santa Cruz) in the 1960s in an attempt to estimate the number of extraterrestrial civilizations in our galaxy with which we might come in contact. The main purpose of the equation is to allow scientists to quantify the uncertainty of the factors which determine the number of extraterrestrial civilizations.

In recent years, the Rare Earth hypothesis, which posits that conditions for intelligent life are quite rare in the universe, has been seen as a possible refutation of the equation.

In planetary astronomy and astrobiology, the Rare Earth hypothesis asserts that the emergence of complex multicellular life (metazoa) on Earth required an extremely unlikely combination of astrophysical and geological events and circumstances. The Rare Earth hypothesis is explained in detail in the book Rare Earth: Why Complex Life Is Uncommon in the Universe, by Peter Ward, a geologist and paleontologist, and Donald Brownlee, an astronomer and astrobiologist.

I found this debate fascinating. I hope you do, too..

Answer 6

I'd say simple life is no rarity but complex, multi-cellular organisms are pretty rare, if not unique to Earth. The requirements for a planet capable of habouring life are quite strict, like you said about Mercury, Venus and Mars.

Earth is just right - the right orbit and right atmosphere and therefor right temperature, climate. It's highly improbable of life randomly forming elsewhere as it seems to have done in the perfect conditions here.

I think the whole Rare Earth theory is definately interesting and food for thought.

Answer 7

No. I believe there are zillions of Earth-like worlds out there, and that THIS one is NO ACCIDENT- but a natural outcome of a set combination of chemical, physical and biological reactions. The reality IS, the universe is of a size beyond our comprehension- so there's PLENTY of room for many multiples of everything (including different forms of life). Remember- our "time-line" on this planet, has been extremely short, & the Earth itself is really not that old- either. We could be as "ants on a rock" as far as some other intelligent forms of life would care to bother with us- and just as naieve. Moreover, I don't know if we'd recognize a "signal" from another world if it kicked us upside the head!- we're so clueless about what's going on in & around us. So I wouldn't be too hasty about declaring the "uniqueness" of life on Earth- if I were you. There just might be some life-form "listening in" from heaven knows where- who's having a good laugh, on us.

Answer 8

no one no ordinary practitioner or lay person can placed a cut back to life on any single different person. sometimes ordinary practitioner tell people life expectancy and that they shouldn't they are actually not god and in extra circumstances than no longer they are maximum constantly incorrect. it incredibly is a huge reason they are beginning as much as stray remote from asserting something to grim. no you would be able to truly say if he will breathe on his own. yet while he's no longer strategies lifeless then which would be one prayer replied. there isnt incredibly adequate information to even provide an opinion incredibly on that. i'm particular they are responsive to his lung ability and point of functionality and in the event that they are removing the ventilator then they could think of he has the flexibility to respire on his own. sometimes a annoying strategies injury would reason a postpone in sending messages via the bodies receptors muscular tissues joints etc that would desire to be affecting his abiltiy to respire thoroughly on my own without the help of the vent. that is been purely one week provide it some time and shop praying god paintings miracles daily and that i think that im so sorry for you and his relatives and that i actually wish each and every thing works out and all those in touch are restored to well-being very quickly superb regaurds

Answer 9

Don't make the mistake of judging everything by human standards.Just because WE can't do it does not mean it's impossible.
There are billions of stars and planets and the chances that Earth is the only one that has "intelligent "life are very slim.
Just because we have not made contact with other life forms does not mean they do not exist.There could be civilisations millions of years in advance of us.Just look how we have advanced in the last 100 years.
Maybe one day contact will be made.I would love to see it in my lifetime.

Answer 10

About the same chanches as winning Florida's lottery first prize.
Still that leaves a huge number of candidate planets in the universe.