If the universe is infinite...?

Question

...then how can anybody logically and rationally declare that we know that there is no other 'life' in the universe except us?

Scarily enough, I've heard plenty of well educate people state this as if it is fact. I just don't understand how anyone can sensibly reach that conclusion. I'm not a highly logical person myself, but it doesn't take much to recognise sheer blindness.

TechnoRat60 - I wasn't referring to experts in the field, and I never said otherwise! I was talking about the view held by a lot of people I have met, heard, or read about. (Hence I used the word 'anyone', as opposed to 'scientists').

Joanne M - see above. :-)

gradjasan: yes, you are wrong in your assumption of what I meant, although I can see why you interpreted it that way. What I meant by 'scarily' is this: I find it bizarre that well educated and sensible people refuse to entertain the possibility that we are not the only beings in existence.

Infinite or not, the universe is more vast and complex than we can fathom. That's what I'm saying.

Answer 1

I think the prevailing theory is that the universe is 'finite, but unbound' - i.e. there a finite amount of matter and spacetime, but no boundaries.

This makes sense because matter bends space, and a large-but-finite universe would fold space in over itself, forming a four-dimensional bubble. If you travelled in any one direction you would never reach an edge, but in theory you'd eventually arrive back in your departure area.

But don't try this at home, because the full size of the universe is larger than the visible boundary - the point at which objects are receding from us at light speed. You'd never reach that boundary travelling at less than light-speed, and there *is* no higher speed than that.

There's another school of thought that considers the possibility that the universe is truly infinite and reaches to infinity in all directions. This brings up interesting possibilities: even with the enormous number of particles in the universe, there is a finite number of quantum states that they can exist in. Eventually they have to repeat. It's quite possible in this circumstance that duplicate universes - with small variations - may actually exist in normal space, without having to bring in alternate dimensions or the Many Worlds hypothesis. If this is true, then almost any physically stable arrangement is possible: a universe that is identical to this one, but where you speak Greek, for instance.

Whichever model is most accurate, the idea that life is confined to Earth seems ridiculous: we know that carbon chemistry spontaneously self-assembles into the kind of chemicals our bodies are made of. There's no reason why this should not be the case in any galaxy. Nor is carbon biochemistry the only possible basis for life. Even though the Earth is a bit special - liquid water; a large stabilising moon; Jupiter around to sweep up most planet-killer asteroids - it won't be unique.

The Drake Equation (q.v.) attempts to set a figure for the number of technological civilisations in our galaxy alone. One result, using best-guess values, is around seven. If this is exactly correct - and it probably isn't - the others could easily be so far away that we will never contact them. Gets lonely out here.

CD

Answer 2

Maybe. WMAP experiments show that the geometry of the universe (not the universe itself....) is flat. Which would indicate that it is infinite. However, there is a very small margin of error in these measurements. So it's possible that the universe is just really, ridiculously, immensely huge rather than fully "infinite". Infinite gravity? No, of course there wouldn't be. What is that even supposed to mean? For one thing gravity acts over very long distances. But it is BY FAR the weakest of all the known forces. It's effects also fall off rather rapidly with distance. Infinite light? Well, no. Light also spreads out over distance. But there would be no way for light from stars to have filled every corner of the universe unless stars had existed for eternity. And we know that the universe is only 13.7ish billion years old. Plus space is expanding. Over really huge distances the cumulative expansion adds up to the point that very distant objects are receding from each other faster than the speed of light. So even if the light did travel forever it would still never reach.

Answer 3

You cant logically or rationally say there is no possibility of life else where.

The universe is not infinate but an entity that is bound by space and time and is expanding. It started from the big bang and space has been expanding ever since.

There will no physical edge of a universe for which you travel out of the realm of space and time. This is because space is expanding faster than the speed of light and we are incapable of reaching that speed. If we did then time will stop. If we traveled faster then you will be able to travel back in time. But this is impossible using the special relativity theory found by einstein.

Light is the only thing which is not bound by space and time and so can exist outside this realm necessary for us to exist.

As for life else where the chances are remote but not impossible, maybe one day we will find some kind of life elsewhere.

Answer 4

I know. I have debated this topic with myself and others many times. Why would small little Earth be the only source of life? I mean there are 7 other planets besides Earth (now that poor pluto has been demoted >:( ) and Earth is one of the smallest planets. There is no logical explanation on why no other life forms exist in the vastness of the univerese besides the small population of humans and animals on Earth. I mean I am not saying aliens are among us, but I mean it is not that impossible to think. Aliens don't have to be little green creatures with big black eyes, they are just any thing that is livign that we are not farmialr with. Heck, there might be like inivisable creatures and thats why we don't know they exist, we don't nesesarly know the conditions. The thing that upsets me the most is when they say that other life cannot exist because of the hottness or coldness or absense of oxygen. That is bull! Maybe other life have assimilated and adapted to their different environment because they don't need oxygen. There are so many other elements and other things we havent discovered. And to think even more, we are only one small galaxy in the whole universe!!! Something else has to exist!!! The small earth in the small milky way cannot be the only life in my opinion. Another galaxy is probably thinking the same thing as us! Funny to think about!

Answer 5

I may be wrong, but the way that your question is worded suggests that you believe there absolutely must be other life besides that on Earth. While I do agree with you that it cannot be ruled out, I don't agree with you that it is a statistical certainty (assuming you do believe that).

Many who try to say that it doesn't exist anywhere else go with the odds on this actually. We'll start with those who believe in the creation theory (since it is logical to assume that life more or less starts the same way no matter where; if we were created then any alien would be too, if we evolved then more than likely they did as well).

If we were created more than likely God chose not to create any more life after us. At first look because God seems to like to create (there are literally billions of different life forms on this planet alone), it would seem life would have been created throughout the universe. But we must remember that early on humans screwed up and disobeyed God. This created a question in which all must see whether we would do better with God as our leader or just leading ourselves. But God already knew the answer, and that we would be growing through a seriously painful mess for having tried to lead ourselves. Not wanting any more of His creations to suffer than already were here, He would probably have held off making any other life until after this question is answered and good is restored (and Satan--or any variation of evil that you believe in-- is destroyed). So more than likely no other life there save what's on Earth.

If we evolved, it is more likely than in the creation theory that life exists on other planets. However, one must realize the sheer odds against life having occurred even once. All the necessary chemicals and elements and molecules and so on had to present and in the right amounts. They had to be near each other and ready to bond. The temperature had to be high enough to induce a reaction between all those things without being too hot to cook to lifeform that first emerges after that reaction. Then everything that lifeform needs to survive (air--whatever that lifeform breathes, be it oxygen or nitrogen or any other breath--food, shelter, etc.) And that lifeform must be formed in such a way so that it can reproduce, and it has to be asexually at least the first time because there is no other lifeform to mix with.

Then the lifeform has to have the extreme luck that the universe more or less leaves it alone as it first starts to grow and multiply. No comets slamming into the planet, no lava reaching it during planet formation/cooling; there is a lot going against the little guy. That it happened once (assuming evolution to be true) and that the first lifeform survived long enough to create a second lifeform and so on and so forth is amazingly unlikely; to believe it happened more than that once is extreme of anyone.

The truth is that while it is possible there are other lifeforms in the universe the odds are very, very strongly against it happening. So they can in fact logically say no other life in the universe and probably be correct. But there is always a chance with so many planets (trillions really) and the possibility of a God that loves to create more life; so it wouldn't be illogical to say life can exist somewhere else.

Answer 6

The universe is not infinite - it's demonstrably expanding, so how can it be?

People who say definitively that there either is or isn't life elsewhere in the universe are narrow minded fools.

Fact is, we have absolutely no idea at present whether there is or not - we don't even have any clues pointing towards either possibility.

Personally, I would be staggered to learn that we were the only life form anywhere - such an incredible waste of space. But who knows?

Answer 7

I see this question over and over again. please could you locate who it was who has this recently(in the past ten years) please? Apart from the church?Please bear in mind that science is a constantly growing evolving subject, one discovery throws years of what is considered 'fact' into chaos. ALL scientists know for a fact that not only is life (by life I would like to stress it could be as simple as a one or two cell organism, not that likely to be humoids)on another planet quite likely, it is almost a certainty. But ever finding it? Not in our lifetime that's for sure. As for the universe being infinate, this is not correct either, the truth is we have no idea how big it is, except that it's still expanding, and we have no idea how long for, or what will happen when it stops. One thoeroy (that was later withdrawn by this world famous scientist) is that it will then contract again, part of the theory toyed with the idea that this retraction would cause the fourth dimension (time) to reverse, meaning that technically it would expand and retract and etc etc for all time, (which would be until the next time it reversed itself)
This is an intensely huge and fancinating subject, put big bang into a search engine and start there.
Hard to explain in a garbled posted answer, but that's how it is.

Answer 8

I think they're not sure now that it is infinite. There may be outer limits, but it's reckoned to contain, more stars with their planets, then there are grains of sand, on all the beaches of the whole world. That's quite a lot really, as good as infinite. There must be other intelligent beings on some other planets. I believe we have not discovered all here yet.

Answer 9

The Universe may or may not be infinite, but the part we can see and interact with is finite and will always be finite. It is so huge, however, that for the purposes of this argument it might as well be infinite---there are almost certainly more than a trillion trillion planets within our event horizon.

Answer 10

The universe is finite.
Although there is no proof there are aliens else where in the universe it is absurd to think we are the only ones.
There must be millions or billions of planets like earth and the circumstances that lead to us must be played out,eventually on any or all of them.
DNA is a language that specifies living things and though they probably don't look like us they could look like anything you could imagine