Why is there only life on Planet Earth?

Question

Of all the planets in the universe,why is there only life on earth?

Answer 1

Say's who?

Answer 2

The question is phrased so naively that I'm tempted to infer you were told by your local priest since alien life might contradict bibical text which is of course 'inerrant'. If you've pondered it and wondered if the question makes sense - it doesnt.

The may well be other life elsewhere in this solar system. There could be anywhere from thousands to hundreds of millions of other life supporting planets in this galaxy alone - and this galaxy is only one of over a hundred billion. I think it very, very, VERY unlikely that we are all there is.

If it makes you feel better I'm sure 7 billion light years away there is a small blue squid like creature asking its three parents why the planet Vierdon Prime is the only planet with life in the universe.

Answer 3

How do you know this? It certainly hasn't been proven. It's nearly certain, IMHO, that there is microbial life on Mars and Europa. If you were asking about sentient life the issues are a little different.

So far we've seen no verifiable evidence of other sentient species. That said, I believe with some certainty that somewhere in our galaxy at some past, present, or future time, a sentient species did/does/will exist.

Why haven't we heard from them?

Perhaps they are not technologically advanced enough to be heard. They may be mastering stone knives right now, or experiencing their own Rennaisance.

Perhaps they are here right now. Any species sufficiently advanced to travel interstellar distances would be able to hide or masquerade with ease. That Boeing 737 that just flew by may be a surveillance craft.

Perhaps they are so far away they will never notice us and vice versa.

Perhaps they existed a million years ago and died out.

Perhaps they will exist a million years from now.

It is really impossible to know for sure.

The Drake Equation suggests that there is sentient life out there. The Fermi Paradox casts doubt. Play around with the calculation form at the second link and see what you think.

Answer 4

Nobody knows that for sure......but life is there on earth because it is the only known planet that provides all the basics. All other known planets are more or less hostile and short on at least one or more of those basics. Perhaps in the future we will able to find a world, beyond the solar system, that might be similar to earth.

Answer 5

We found Pluto that we thought was made of ice but it was made of volcanos and other materials, Mars is very cold and is closer too earth than we once thought but no life is on Mars, then we found this Super Earth in are solar system called I think G20321 a Super Earth and they think one side of the Super Earth has the past and the present and the other side has the present and the past know body knows what it would be like as it is about 1000 light years away and we thinking the other day NASA might send a Robot too this Super Earth too find out what it is made off, they think if any life forms on this Super Earth would be much weirder than this planet that we live on called Earth.

Answer 6

I’ll take that bet, Fiona S. When answering a question like this you have to assess just how fantastically unlikely it is that life ever arose on any planet anywhere, including ours. First, the planet has to be exactly the right distance from the sun – it has to be in the star’s biosphere. Too close, and it’s too hot for liquid water, too far away, and it’s too cold. Of course, that only counts if the planet has an atmosphere. Our moon is inside the sun’s biosphere but cannot support liquid water because without an atmosphere the surface is either too hot or too cold to allow standing water to stand for very long. As well as an atmosphere you need a magnetic field around the planet, so the composition of the planet is essential. Nickel/iron core, or forget it. No magnetic field and the sun with scour the surface clean of any speck of life before it can think of replicating. You need an ozone layer, too, while we are about it – ultraviolet light is an excellent disinfectant and kills all kinds of primordial life. The solar system itself has to pitch in, too. Further out – at exactly the right distance from the sun – you need a nice big gas giant or two. Jupiter is the vacuum cleaner of the system, and without it Earth and all the other inner planets would be constantly bombarded with space debris. If Comet Shoemaker-Levy hadn’t hit Jupiter, it would have hit Earth. Not a single bacterium would have survived the impact. Once all of the big stuff is in place, the process of starting life from inorganic molecules can begin. We need phosphorus, nitrogen, oxygen, sulphur, carbon and hydrogen in exactly the right proportions dissolved in water in exactly the same place at exactly the right temperature. Now we need an electrical current to start the ball rolling and Eveready batteries were pretty thin on the ground in 4,500,000,000 B.C. Lightning will do, as long as you’ve got the kind of atmosphere where you actually get lightning. And it strikes in exactly the right spot. At exactly the right time. This MIGHT create amino acids from the primordial soup, and they are the beginning of the beginning of the start of the beginning of life. As molecules go they are pretty robust but they are very susceptible to damage by radiation so it would be handy if our planet wasn’t radioactive at all. Oh, and the atmosphere and all the standing water has a pretty neutral Ph. And there’s that old pesky problem of temperature again. See the problem? Everything, every single element that turns a floating mudball into a blue and green planet bustling with life has be in exactly the right place at exactly the right time for the next step to take place, and that has to happen for about five or six million different processes one after the other in precisely the right order and ... I’m wearing meself out here.

The practical upshot is it might well be that there are 50 thousand trillion planets in the Universe and the chances of life arising on one of them is 1 in 50 thousand trillion. It might be 2 in 50 thousand trillion which means there might really be Klangons out there. Nanoo fcuking nanoo, yourself. But – excepting the possibility of us one day finding mummified amoeba in the soil of Mars – we will never, ever know. The chances of life arising on a planet are, as I have said, vanishingly small. The chances of it arising on two planets within interplanetary commuting distance are nil in 50 thousand trillion. We will never even hear from another civilisation, let alone visit one. We will never even be aware of their existence, nor they of ours.

Answer 7

Earth is the only planet where life has been found by us. That hardly means that there are no other planets anywhere in the universe that don't also have life.

Answer 8

How do you know there is life only on Earth? Have you travelled to all the trillions of planets in the Universe? Jesus, how arrogant can you get?

Answer 9

In my opinion, I believe that life really should exist on another planet somewhere. I mean the odds that we are on the only planet holding life in the possibly untold trillions of planets located in the universe seems a bit unlikely

Answer 10

Hey, that's a bit of a naive question. We don't know whether there's life on other planets or not, which does not imply that there isn't.

Space exploration is still very much in it's infancy. Statistically, the chances of us being alone are very, very small. Remember, we don't even know how many planets or suns are within our own solar system - so there could even be life that's closer to us than we think.

Answer 11

Ah, lots of planets have water, it's a very common substance, however imn out solar system it's mostly ice. life as we know it needs floating water. Mars might have had this, but it looks like the climate on Mars took a wrong turn a few billion years ago. THere might still be life there in the form on single cell organisms, but we need to be able to drill down the ground to find out. Europa is also a candidate for life asn it seems that it has floating water under it's cover of ice (2 - 3 km deep!).

There might be live in other solar system, but its very hard for us to see, so far we can only find huge planets around other stars, not planets like ours, but in a few years we should be able to see them and then we might be able to see if they contain oxugen and or methane, which can be an indication that life is present, however to be sure we must go there, which we unfortunatelly wont be able to do in a very long time