Is there life in the universe, and if so has it visited Earth?

[vivesdn]

If evolution work in the same way, intelligent life would have come to take resources from our planet, I guess.

 

[Ivan Seeking]

But then going by your way of thinking you may as well say that as theirs no evidence that super intelligent alien life forms haven't found a way to manipulate space then theirs no reason to disbelieve someone who tells you that aliens are walking our streets kidnapping and performing operations on us in their cloaked invisible spaceships.

Not true. We know that life exists. And we think that Earth and sol may be very ordinary, so we are led to consider that life may be fairly common. However, we don't know that ftl travel is technically possible, so it becomes a complete leap of faith to assume otherwise if lacking any direct evidence.

Theirs no harm in dreaming or wishing it to be true but sorry without ANY form of evidence in my opinion common sense should take over..

The evidence at this point lies in comparisons between what we know about Earth and life, and what we know about the rest of the galaxy. Since, due to our technical limitations, we have no definitive test for life elsewhere, we can have no direct evidence, but we hope to look at the atmospheres of distant planets for the chemistry of life as we know it. You are concluding that because we don't know how to, or because we are technically too limited to look, as yet, it ain't there. You are arguing the ostrich conjecture.

 

[ukmicky]

Not true. We know that life exists.

Yes ok i give you that one. Life does exists as you say, but fortuanatly for me we have only evidence for it on earth.

And we think that Earth and sol may be very ordinary so we are led to consider that life may be fairly common. .

You said it "we think" which is as good as a guess is it not

The evidence at this point lies in comparisons between what we know about Earth and life, and what we know about the rest of the galaxy.

What do we know about the rest of the galaxy in respect to life on other planets ,absolutely nothing.

Since, due to our technical limitations, we have no definitive test for life elsewhere, we can have no direct evidence, but we hope to look at the atmospheres of distant planets for the chemistry of life as we know it.

And even if in the future they were to look out their and find a planet that resembled the earth. All the sensible scientists will still only say something like ,"the possibility exists that their could be life on it" Because the only way to prove it would be to go their.

You are concluding that because we don't know how to, or because we are technically too limited to look, as yet, it ain't there.

yes ,because it might not be there and unless proof comes along that's the sensible way to go.

Ivan. what your basically saying is you believe in something that you have no proof exists. You use the Earth as your evidence for life beyond Earth but just because their is life on Earth doesn't mean it has to be elsewhere.

Some of the lifeforms on Earth maybe very hardy but life isn't something which happens very often without the aid of a another living organism.
Consider how old the Earth is and how many unrelated forms of life their are their on our little rock, and that should tell you how hard it is for life to appear from a bunch of chemicals and how unlikely life on other planets could be.

You are arguing the ostrich conjecture.

Ostrich ,dont you mean the Ravenous Bugblatter Beast of Traal. And before you say theirs no such thing i say prove it. :)

Anyway the ostrich is blindfolding its view of something it knows is their. We don't know life is out their, because as human beings we have evolved to not believe something is fact without seeing evidence for it first , and you can't use one example (the earth) as your evidence of life on other planets, to do that is very unscientific you know. :).

If this were a court of law you would lose because in my opinion your beliefs are based on assumptions,desire's and wishes ,im not saying theirs anything wrong with that as sometimes just like in the wizard of OZ wishes can come true ask Dorothy;) :)

 

[arildno]

There are many ways to substantiate a higher estimate of the probability of life existing elsewhere other than by traveling there.

First and foremost would be to answer:
Under what general chemical conditions will life with a high probability develop?
This is a question that is answerable without ever vising another planet; for example by careful (and loooong) lab experiments here on Earth.

Then, knowing that astronomers can glean pretty much info about chemical conditions elsewhere through their observations, comparisons could be made to make more solid estimates of the probability of life elsewhere.

A difficulty that may well arise, of course, is that the information gleaned by astronomers remains too scarce to distinguish between cases where the probility of life is low, and cases where the probability of life is high...

 

[vivesdn]

But the question is not if life exists on other places. The point is if intelligent life has developed a technology that allows space/time travelling, as no one would visit another planet to come back at home and see that 1000 years have passed and no one is there.
Or, at least has developed space ships to move the whole culture through space searching for new places to live.
Both possibilities are, I guess, several orders of magnitude lower than the simple existence of living beings.

 

[arildno]

The POLL is concerned with whether life has visited Earth, the thread headline combines two questions, whether life exists elsewhere in the universe, and the pol question.

 

[vivesdn]

In my opinion, life must be, is developing in parallel in other places. We are not as special as we want to think. But I'm convinced that if intelligent, able to travel to other planets, life exists, then we would know.

 

[SGT]

There is no evidence to rule out life on other planets. In fact, what we do know suggests that we are almost certainly not alone, so to leap to any conclusion is a leap of faith at best.

There is no evidence to rule out the existence of invisible pink unicorns. So, in your opinion, denying their existence is a leap of faith.

 

[Pythagorean]

There is no evidence to rule out the existence of invisible pink unicorns. So, in your opinion, denying their existence is a leap of faith.

this does actually bring up a point I've wondered about.

The argument for other lifeforms is similar to that of parellell universes, that it's a matter of statistics that atoms will come together in the right way under the right conditions to form life just like it did on Earth.

With that logic, wouldn't it be just as easy to say the existence of pink unicorns has a high probability of occurring at least somewhere in the universe?

I don't know. It's pink, and it's a unicorn. It's an emotional argument because it's designed to disgust most males (ewww, pink unicorns! I don't believe in those, I'm not gay!).

It's also an emotional argument in that it's a ridiculous postulation "Pink Unicorns? Now that's tacky!" So you're trying to attach that ridiculousness to the idea of life in the universe.

Now, I can't really judge whether or not there is other life in the universe, because I don't understand the statitistics (and I haven't studied cosmology or astronomy in depth)
but I'll tell you what: I have more respect for someone researching the possibilities of other life than someone searching for the possibility of pink unicorns, so they're really not even comparable.

Pink Unicorns would probably only help out those rich people that buy tigers, then can't handle them when they grow up and leave another cat stranded in the US, costing tax payer dollars in the form of wild animal shelters, so even if it was a credible assumption to start with, it's a worthless pursuit.

Other life forms, on the other hand, could contribute to our technological, scientific, and societal understanding, so it doesn't matter how much evidence we have. That's the whole point of research, to discover.

Also, the idea that we're alone in the universe can be likened to us thinking we're the center of th universe. Make sure the assumption comes from a logical place and not an emotional, self-important one.

I don't care about ET's, it's not my area. I don't criticize or support the research and that's because it's a shot-in-the-dark (both financially and productivity-wise), but skeptics aren't supposed to discourage people from researching and asking new questions. They're supposed to discourage deceit and misunderstanding.

 

[Ivan Seeking]

There is no evidence to rule out the existence of invisible pink unicorns. So, in your opinion, denying their existence is a leap of faith.

We don't and can't know if life is out there and that's a simple fact. To "believe" that life does or does not exist beyond Earth is a faith statement. That is also a simple fact. Of course, this excludes those who claim direct observations of ET. Ironically, they [allegedly] are the only ones allowed [near] logical certitude.

There is also reason to believe that life may be common; that is also a fact. I am not aware to any reason to believe that pink unicorns might exist.

 

[SGT]

this does actually bring up a point I've wondered about.

The argument for other lifeforms is similar to that of parellell universes, that it's a matter of statistics that atoms will come together in the right way under the right conditions to form life just like it did on Earth.

With that logic, wouldn't it be just as easy to say the existence of pink unicorns has a high probability of occurring at least somewhere in the universe?

I don't know. It's pink, and it's a unicorn. It's an emotional argument because it's designed to disgust most males (ewww, pink unicorns! I don't believe in those, I'm not gay!).

It's also an emotional argument in that it's a ridiculous postulation "Pink Unicorns? Now that's tacky!" So you're trying to attach that ridiculousness to the idea of life in the universe.

Now, I can't really judge whether or not there is other life in the universe, because I don't understand the statitistics (and I haven't studied cosmology or astronomy in depth)
but I'll tell you what: I have more respect for someone researching the possibilities of other life than someone searching for the possibility of pink unicorns, so they're really not even comparable.

Pink Unicorns would probably only help out those rich people that buy tigers, then can't handle them when they grow up and leave another cat stranded in the US, costing tax payer dollars in the form of wild animal shelters, so even if it was a credible assumption to start with, it's a worthless pursuit.

Other life forms, on the other hand, could contribute to our technological, scientific, and societal understanding, so it doesn't matter how much evidence we have. That's the whole point of research, to discover.

Also, the idea that we're alone in the universe can be likened to us thinking we're the center of th universe. Make sure the assumption comes from a logical place and not an emotional, self-important one.

I don't care about ET's, it's not my area. I don't criticize or support the research and that's because it's a shot-in-the-dark (both financially and productivity-wise), but skeptics aren't supposed to discourage people from researching and asking new questions. They're supposed to discourage deceit and misunderstanding.

I did not use the IPU to ridicule the idea of extraterrestrial life. I only used it to show that it is impossible to prove an universal negative. We can´t prove that extraterrestrial inteligence or invisible pink unicorns don´t exist, but this does not prove the contrary hypothesis that they do exist.
Of course the likelyhood of extraterrestrial life and of IPUs is not the same. We know that intelligent life exists on Earth, we know that the building blocks of life exist elsewhere in the Galaxy, so it is likely that life has arisen in other planets. Since we have never seen a unicorn pink or any other color, the likelihood of their existence is lower.
BTW, there is nothing gay in the IPU. Everybody knows She is a female.

 

[SGT]

We don't and can't know if life is out there and that's a simple fact. To "believe" that life does or does not exist beyond Earth is a faith statement. That is also a simple fact. Of course, this excludes those who claim direct observations of ET. Ironically, they [allegedly] are the only ones allowed [near] logical certitude.

There is also reason to believe that life may be common; that is also a fact. I am not aware to any reason to believe that pink unicorns might exist.

See my answer to Pythagorean, above.

 

[Ivan Seeking]

I did not use the IPU to ridicule the idea of extraterrestrial life. I only used it to show that it is impossible to prove an universal negative. We can´t prove that extraterrestrial inteligence or invisible pink unicorns don´t exist, but this does not prove the contrary hypothesis that they do exist.

And no one said anything about proof of life.

We can't yet even look for ETs. If we look and find many worlds where life could exist but doesn't, then we might begin to argue for a rare earth. But until we can begin to look for life elsewhere to some reasonable limit, we are not arguing for proof of a negative, we are arguing that we can't and don't know. To "believe" for or against is a faith statement. This is not just my opinion. It is a fact.

 

[Pythagorean]

Of course the likelyhood of extraterrestrial life and of IPUs is not the same. We know that intelligent life exists on Earth, we know that the building blocks of life exist elsewhere in the Galaxy, so it is likely that life has arisen in other planets. Since we have never seen a unicorn pink or any other color, the likelihood of their existence is lower.

it's not just about the likelihood of the idea, it's about the usefulness of it. I don't pursue proof of alien life because I don't have the balls and I'm not a risk-taker. It's a fun and interesting topic, but I wouldn't let it interfere with my professional life. If things change, and proof was produced, it could become part of my professional life, but either way I wouldn't discourage the research.

The UPI on the other hand, is completely useless and impractical to me.

 

[DaveC426913]

If things change, and proof was produced, it could become part of my professional life

Yep. There're those who like to be in on the ground floor - big risk, huge gain. And there're those like yourself, who prefer blue chip stock.

Jodie Foster in The movie Contact, was of the former type. And she got to be the pilot.

 

[SGT]

it's not just about the likelihood of the idea, it's about the usefulness of it. I don't pursue proof of alien life because I don't have the balls and I'm not a risk-taker. It's a fun and interesting topic, but I wouldn't let it interfere with my professional life. If things change, and proof was produced, it could become part of my professional life, but either way I wouldn't discourage the research.

The UPI on the other hand, is completely useless and impractical to me.

This is of course your opinion and I respect it. People much more knowledgeable than you and I, including the late Carl Sagan, are searching for evidence of extraterrestrial intelligence (with no results until now).
As for the IPU, she is very useful for Her worshippers: http://www.geocities.com/ipu_temple/

 

[Pythagorean]

Yep. There're those who like to be in on the ground floor - big risk, huge gain. And there're those like yourself, who prefer blue chip stock.

Jodie Foster in The movie Contact, was of the former type. And she got to be the pilot.

I wouldn't say I "prefer bluechip stock". I like to be on the ground floor; I still expect to have ideas of my own, in my field, that no one has ever thought of before, and that may even be counterintuitive, take time for the public (and maybe even the rest of my field) to chew, revolutionize science, etc, etc. I would hope that's what I'll be doing, that's why I'm training as a scientist, to discover things!

nor do I "prefer bluechip stock" when it comes to ETs. It's just a fact that if proof was produced, it would have a good chance of becoming part of my professional life (as a side-affect).

 

[Chronos]

The expense of 'visiting' extrasolar planets is prohibitive by science as we know it - and surely extravagant by any science we don't know. Probes, however, seem highly plausible. I sincerely doubt, however, the 'aliens' would give a rats ass if they crashed on earth. What would we do - retaliate?

 

[Ivan Seeking]

The expense of 'visiting' extrasolar planets is prohibitive by science as we know it - and surely extravagant by any science we don't know. Probes, however, seem highly plausible. I sincerely doubt, however, the 'aliens' would give a rats ass if they crashed on earth. What would we do - retaliate?

It would not be extravagant by science that we do not know.

But as for alien probes [and not the kind commonly reported]

Inscribed matter as an energy-efficient means of communication with an extraterrestrial civilization

...The results suggest that our initial contact with extraterrestrial civilizations may be more likely to occur through physical artefacts—essentially messages in a bottle—than via electromagnetic communication.[continued]

http://www.nature.com/nature/journal/v431/n7004/abs/nature02884.html

 

[Ivan Seeking]

Interstellar Espionage: While We're Watching Mars, Could Someone be Watching Us?
Jan. 22, 2004
by Seth Shostak - Senior Astronomer

Have aliens sent mechanical emissaries to our solar system -- robotic probes on a snoopy mission to reconnoiter Earth?

Its certainly an intriguing idea: sophisticated spy satellites from light-years away monitoring our planet, watching the slow evolution of life, and reporting back to their alien masters. Such a scenario has frequently appeared in the SETI literature, and Allen Tough, at the University of Toronto, has urged that we take the idea seriously enough to make a search for these alien "bugs." [continued]

http://www.seti.org/site/apps/nl/content2.asp?c=ktJ2J9MMIsE&b=194993&ct=220901

 

[Ivan Seeking]

Earth-like planet found
https://www.physicsforums.com/showthread.php?t=167340

 

[StuMyers]

Neat. Streching the definition of "Earth-like" a bit, but nifty.

When they look at the star wobbling, I'd guess that they assume rather than calculate that the orbiting planet in question is a single planet, and not some dual trojan thing?

 

[Schrodinger's Dog]

I'm going to bump this thread, because it's got a lot of scope and because I want to read that article in the newspaper about the "Earth like" planet and that link on that thread doesn't work.

No wait, the second link works, sok, anyway worth bumping anyway, some quite interesting developments.

And the Drake equation is possible given the criteria and confirms there must be intelligent life: maybe in the galaxy, but definitely in the universe by the laws of probability.

The Drake equation doesn't confirm anything. The inputs are guesses.
1) We don't know the likelihood of life arising, although it doesn't seem unlikely at all.

Given assumption x then y.

We did this pages ago, it's meant to be a hypothetical question, like the Drake equation, that was the point

 

[Jimmy Snyder]

Even though I married an alien, legally of course, I voted against them. However, just to be fair, I applied the Drake equation to my own situation. Here's what I came up with:

N* = the number of stars in my house: None, but don't tell my kids that.

fp = fraction of stars with planets around them: 100%. Everything revolves around the kids.

ne = number of planets per star ecologically able to sustain life: None so far, but according to me, a fetus isn't viable until it graduates medical school. Looks bad just now, but they say the darkest hour is just before dawn.

fl = fraction of those planets where life actually evolves: 100%. Near as I can make out, the next species after Homo Erectus will be Homo Reclinus.

fi = the fraction of fl that evolves intelligent life: 0%. Let's not go there.

fc = the fraction of fi that communicates: 0%. So wack it's bogus, Reet?

fL = the fraction of the planet's life during which the communicating civilizations survives: 100%. I have my doubts, but my mother assures me that she has seen a generation overcome even worse odds.

My conclusion is that no alien could have survived the harsh environment here.

 

[Schrodinger's Dog]

Hehe very good.

Don't say "without an intelligent designer" will you.

I cite the fact that life with or without intelligence but with, some sort of wisdom or sapience - although hell knows where it's gotten too in our history - and an ability to communicate although somewhat remedially and often with double speak has evolved: assuming that such an occurrence is at least possible by a priori information- is there likely to be at least something vaguely intelligent in the Universe, because as already noted there is bugger all sign of it down here

R - represents the number of stars in the Milky Way Galaxy R = 100000000000(100 billion) Currently in existence.
Fp - Fraction (percentage) of those stars with planets Fp = .05 %
Ne -Number of "Earth's" per planetary system Ne =.001
Fl - Fraction (percentage) of those planets where life develops Fl =.3 %
Fi - Fraction (percentage) of sites with intelligent life Fi =.2 %
Fc - Fraction (percentage) of planets where technology develops Fc = .01 %
L - "Lifetime" of communicating civilizations (years) L = 10,000,000
R * Fp * Ne * Fl * Fi * Fc * L = N
N - Number of communicative civilizations=300

My best guess although fairly conservative is 300 planets with intelligent life and communicating, that means sparsity of communicating life, but not no chance of us or them meeting alien life.

 

[Ivan Seeking]

Astronomers have found the largest negatively charged molecule so far seen in interstellar space. The discovery, of an organic compound, suggests that the chemical building blocks of life may be more common in the Universe than had been previously thought. [continued]

http://www.nature.com/news/2007/070723/full/070723-5.html

 

[rocomath]

maybe we're the most advanced civilization in the universe and it's up to us to visit our worlds :-]

but we sure have a long way to go till that happens.

 

[Quatl]

Let's hope when they do visit us they don't do what humans would do when visiting other civilizations. Kill them all. Or else we certainly would know if they visited us!

Don't be so pessimistic about your own species ... I think we'd at least attempt to enslave them first

 

[Schrodinger's Dog]

That's what we did on Earth, find a backward culture and rape it for all it's worth, you'd hope in space we we're sending intellectuals, not greedy idiots backed by self righteousness? Still it's a concern our track record is awful.

That's why I hope we aren't the smartest race out there, because we is dum and unwise. And if organic compounds are more common place as Ivan's link suggests, well let's just hope...

I like to think if you can conquer the vast gap between worlds, you didn't just do it to supplant other cultures with your own. But to be frank it's eminently possible that that's what drove an alien race to find new worlds in the first place; just as we did with greed and a need to out resource our neighbours.

 

[Ivan Seeking]

'It might be life Jim...', physicists discover inorganic dust with life-like qualities

https://www.physicsforums.com/showthread.php?p=1398096#post1398096

 

[Ivan Seeking]

Comet probes reveal evidence of origin of life, scientists claim

...The Cardiff team suggests that radioactive elements can keep water in liquid form in comet interiors for millions of years, making them potentially ideal “incubators” for early life. They also point out that the billions of comets in our solar system and across the galaxy contain far more clay than the early Earth did. The researchers calculate the odds of life starting on Earth rather than inside a comet at one trillion trillion (10 to the power of 24) to one against. [continued]

http://www.physorg.com/news106316780.html

 

[Ivan Seeking]

The theory that comets seeded life on Earth gained support Thursday, with a team of scientists experimentally proving that the raw materials for life hitchiking aboard a space rock could survive the trip to our planet.

...In Blank's experiments, not only did a good fraction of the amino acids survive the simulated comet collision, but many evolved into chains of two, three and four amino acids, so-called peptides. Peptides with longer chains are called polypeptides, while even longer ones are called proteins.

"We saw variations in the ratios of peptides produced depending on the conditions of temperature, pressure and duration of the impact. This is the beginning of a new field of science," Blank said.[continued]

http://www.space.com/scienceastronomy/solarsystem/comet_life_010405.html

 

[muralic]

our tecnology should be more developed,in order to find et's. what if they are thousand years ahead of us.what if they are more intelligent then we are.they would have well developed tecnologies than what we have now.there are no places for speculations here.lets wait and see what happens

 

[DaveC426913]

there are no places for speculations here.

Seems to me this is the quintessential topic for speculation.

 

[Capuchin]

do you think the intelligent life has visited Earth?

Yes. It evolved here. (what?)