There are 450 billion galaxies in the visible universe (give or take a few hundred million).
That’s a huge number, much bigger than merely saying it would lead you to suppose. So try this…
If every one of the estimated 450 billion universes were represented by a frozen pea, then there would be enough of them to fill up the old “Boston Garden” from the parquet to the rafters (or so says an Astrophysicist named Bruce Gregory) and I believe that Carl Sagen stated that the very average sized Milky Way Galaxy has about 400 billion stars residing within it! Can anyone faced with these numbers really honestly say that they believe the Earth is the only planet with intelligent life living on it in this extremely, extremely vast universe that we reside in?
In addition to these crazy numbers you also need to add the number of planets revolving around all of these stars in all of these galaxies. The number is not known but the only one that we can accurately count has at least 9 of them here so I think it would be safe to factor in and at the very least double the amount of stars to get an extremely conservative number of the planets.
This by it’s self doesn’t prove a thing and that’s absolutely true. But what type of evidence to you point to in order to refute the possibility that intelligent life can be found throughout the endless universe. There are a lot of people that actually believe that we really are alone and they all seem to have come to this conclusion on blind faith alone. I just need to hear a single intelligent thought that supports the contrary.
Please enlighten me!!
Nothing to add to the contrary, but I think it stems from simple ego. People want to feel special, powerful, knowledgeable, and in control. The prospect of millions of worlds with intelligent life is too frightening for most. For the others, It’s a matter of pig-headed stubbourness. It’s like bigfoot or other unknown or fringe science. “Well, we haven’t seen one yet so it can’t POSSIBLY exist.” :rolleyes: I’m all for proof before belief for the little things like bigfoot, but the numbers are stacked in the odds of aliens. Personally, I hope I get to see some before I die.
It seems like a mathematical certainty that life would evolve on other planets. In fact, it would would almost require supernatural intervention for ther not to be other life in the universe.
Don’t count on seeing it anytime soon, though. The vastness of space and the probable sparseness of life would make it difficult, if not imposible, for these life forms to find each other. It would take hundreds or thousands of years to travel from one inhabited system to another even at the speed of light.
I think it’s a virtual certainty that life has arisen in many, many places in the universe.
But the important question is whether or not life elsewhere has progressed to the level of civilization and self-awareness and the technology required to make itself known across light years.
There are huge numbers of stars, but if you start elminating candidates the number starts to get dramatically smaller. First, the galaxy has to be just a certain age. A star must be the right distance from the galactic center. A star has to have formed a planetary system. In that system, a planet has to be in just the right position. The star must be of a certain type and size. The planet has to be a certain type. There’s evidence that you need to have a Jupiter-size planet to sweep up debris or the planet will be continuallly pummelled. Also, a chance enounter with another object almost its size caused it to become not-quite a binary planet, which kept the Earth with just the right tilt.
Over the aeons, this planet must have avoided major impacts with other objects for a period of billions of years while life evolved. We still don’t have a good sense of how likely that was.
Then there are any number of possible flukes that happened as life began to evolve.
And think of it this way: if intelligent life is inevitable, than at some time during the creation of the universe intelligent life had to spring up on one planet first. And those people would be asking exactly these questions. So it might well be us.
I don’t know. I really believe that if here, than why not there, I am almost certain that within the next 75 years they will find proof that life once existed on Mars. If water is just so abundant on our plant and that it seems to be one of the most important precursors to the development of life that surely Mars with all of the apparent evidence for free flowing liquid water it’s almost a given. Well, bacterial life at the very least. With all of the possible places that there are out there I am positive that there must be (just in the law of averages) that there are many planets that closely resemble the factors we have here. Entropy works against all organized systems and they may all have exhausted their resources and went extinct already or perhaps the amino acids are just now starting to be mixed at another location but there has to be someone else out there thinking the same things that we are. It may ironically sound like a bit of blind faith on my part but the odds are defiantly in my favor. I think!!!
Your estimate of 450 billion galaxies is a little small. This map of the universe estimates 100 billion large galaxies like the Milky Way and 10 trillion dwarf galaxies.
Of course, your thesis that life must exist elsewhere in the universe is difficult to refute. However, for this galaxy, we may indeed be alone.
For even the simplest life to develop, the “interesting” atoms from more than one generation of stars is required (ie. new elements produced in star core, then supernova scatters them, then new star including these elements produces further new elements, another BOOM! and so on). It is unlikely that there are too many other third generation stars like our sun in terms of a proportion of those visible, and so life might not have been all that likely until a billion years ago or so.
Plus, SETI tells us that nobody within 5 light years (see map) is using a TV or radio, nobody within 50 light years (map) is using military radar, and nobody in this galaxy ever swept the skies with a gamma beam continuously for (at most) the last 100 millennia just to see if anyone sent anything back.
While I have no quarrel with your hypothesis, I do wonder about Carl Sagan’s estimate of the mass of the universe, just before the Big Bang, which was “…the size of your thumbnail,” he said.
Later, others upped it to “…the size of your fist.”
We’re gonna get trillions of galaxies with googols of stars, etc., from a fistful of pre-Bang shit?
Linear travel is for dweebs, no one travels like that any more in the modern universe. Inter-dimensional travel is where it’s at, according to superstring theory.
I feel obliged to point out that we didn’t have the capability of doing any of that just a couple of hundred years ago, and within a thousand years we will likely no longer be doing any of that any more (either because we’ve moved on to better technology or we’ve managed to remove ourselves from the food chain). That makes this a pretty small window to be looking through.
I’ll freely confess to not knowing what this involves (or even is), so I’m not sure whether it’s a process that’s easy/feasible (IE, is it something that someone’s going to actually do).
The mass of the universe (or at least the energy density, which is the thing that cosmologists care about) is a constant. What our friend Carl was talking about was the SIZE of the universe. That’s a physical size only. Everything that we observe today at one time was in that “fist”. This is not up for debate: it’s an observed fact.
Yes. We are. That’s the way things work. Think of it this way: we have a tremendously large density in the early universe which means that things are colliding and existing on top of each other with a crazy amount of energy. Atoms, light, protons/neutrons/electrons, etc. do not exist as you see them today. Instead they are in equilibrium with each other. That means that, for example, electrons and positrons find each other quite often and annihilate to form light particles (photons) that decay to form electrons and positrons which annihilate ad infinitum.
As the universe expands, it gets harder and harder for things to stay in equilibrium because it turns out that a) light locally appears to lose energy as you expand the box it sits in and b) things just can’t find each other and interact anymore. It turns out that light losing energy means that you leave this phase of equilibrium and you are left with the relatively lumpy universe we see today repleat with neutral atoms and structure (things like you and I) which are ridiculously overdense (compared to the rest of the universe) simply because they gravity causes them to collapse and other processes allow them to cool. The variety of stuff we see today still has the thumbprint, however, of this initial “fistful”. In particular, we see the Cosmic Microwave Background that gives us a signature of what the universe looked like when all the electrons found nuclei and no longer were in equilibrium with the photons that were running around. These photons keep the signature of what the universe looked like back then, and we have gotten instruments that have allowed us to read this signature and determine that, yes, our friend Carl is basically right on this subject.
It’s not just the distance, and discovery of plausible interstellar travel, it’s the time. We aren’t just looking for evidence that intelligent life has evolved on other planets, we’re looking (or hoping) for it to have developed concurrently in time with our own civilization.
I think the best answer to the OP remains:
THERE IS AS YET INSUFFICIENT DATA FOR A MEANIGFUL ANSWER.
Hopefully, the two Mars rovers will soon provide evidence of life existing on another planet other than Earth. All signs point to nothing much more than fossilised bacteria, but it would still rank as one of the most significant scientific discoveries in human history. I think it’s wonderful that this work of NASA’s is being shared so freely with the rest of the world, and IMHO, serves as a model of how we’re going to progress in space in the future.
The existence of oxygen and carbon on a planet in another solar system has also been recently verified (no link, sorry). With the nascent ability to explore far-away planetary systems improving rapidly, the number of potential ‘life sites’ for study is only going to increase.
The really exciting thing about these two, and related projects is that we are for the first time attempting to study life outside the one ‘laboratory’ that we have any experience of: our own planet. I am optimistic that our future discoveries within the lifetime of most present Dopers will answer some key questions about how likely life is to develop, and to what extent it may flourish.
Whilst this isn’t the IMHO forum, I’ll answer the question posed with, “No. I’m sure that intelligent life exists somewhere else – either right now, in evolutionary ‘prototype’, or in fossil records.
An easy way to explain why there is only a single intelligence in the universe is to invoke the anthropic principle. Put simply, if we assume the likelyhood of life forming is much lower than the number of stars in the universe (say 1 in 10^100), then the chances are that there is no other life in the universe. However, there must be at least ONE intelligent life in the universe otherwise there wouldn’t be anyone wondering why space is so empty. Thus, it’s quite possible that we may indeed be alone.
Yes, it’s mine. Nobody can have it. Well, except catastrophists that already think the way I do.
Yes, life is everywhere. Obviously life has been living all over the universe for billions of years. The vent creatures and chemol… germs that eat chemicals have proven that life ain’t a wuss.
OK, so, why aren’t we a member of the Federation of Planets yet?
Um, disasters, radiation, plagues, supernovae… The universe is wonderful at creating life, to balance how wonderful it is at exterminating it.
