Aliens - Are they out there? Have they visited us? And related questions

[Violet]

I am not assuming we are the first. But it is a different kind of narcissism to assume we or our planet warrants any special attention, or that any who came before us would be motivated in such a way that they would visit us.

Earth is reasonably suited to most of the life I am aware of, and earth has many resources, not to mention that our race is suitable for a number of forms of manual labor, with enough intellectual capacity to perform such reasonably complex tasks as language and science. I'd say we make good cheap slave labour, and there's 7 billion of us, and we have little difficulty breeding more. That we haven't yet been carted off by slave traders, and also haven't been exterminated for our resources and/or planet, admittedly makes me feel more safe in regards to the galaxy.

---

I heard an interview with an archaeologist who said he hears the arguments like that for Atlanteans and says "where is their garbage then?" That we just don't see anything in the archaeological record that can't be identified with one particular known historical group. If the aliens were here, either it was way before humans were around, or they were the neatest bastards to walk the face of the earth.

Strange that i interpreted that to mean that the aliens were all gay >_>

[Welsh cake]

That's 60,000,000,000,000,000,000,000 Planets

Even if 1/10 are in the goldilocks zone.

That's 6,000,000,000,000,000,000,000 planets in the goldilocks zone.

If only 1% of those have the conditions necessary for life

That's 60,000,000,000,000,000,000 planets where abiogenesis can happen

What estimates would you hazard that said planet not only existed within the goldilocks zone but also had a Jupiter-like gas-giant planet neighbour that acted like a "cosmic vacuum" preventing the majority of impacts from meteorites and stray comets obliterating the celestial body?

Not to mention calculating the instances where life can arise from non-life and evolve to a sentient race that forms a cooperative society that survives long enough from internal and external factors (wars, disease, mass extinction events and so on) to prosper and become so ridiculously technologically advanced they've developed a means of detecting Earth-like planets that can support life and construct the means to achieve faster than light space travel to get there?

While still possible, I have to admit the odds (if they can ever be worked out) aren't simply minute, they're infinitesimal.

[theVOID]

I wouldn't bother accounting for it, there would be no data to consider in making estimates.

[Anomalocaris]

@welsh cake
It appears Jupiter like planets are very common in planetary systems. Very large Jovian planets are to be found in majority of the planetary system we know of. So I think the odds of a planetary system having large planets to sweep up debris from primodia disk and deflect later comets is high.

Also, I think you unnecessarily narrow the range of planets that might harbor life. There is no reason to suppose, for example, that large Jovian planets with long lasting internal heat sources can not support life in it's own atmosphere without being in the goldilock zone. Also there is no reason to suppose a Jovian system might not harbor life on it's moons, with energy provided by tidal flexing of the moons resulting from gravitational interaction between different moons in the same system, such as we find on Io and Europa. We have no idea what is the ratio of worlds that could support life with energy sources other than it's sun to the worlds that is in goldilock zones around the sun. It may well be that majority of life sustaining environments are not in the goldilock zone.

As to the chances of intelligent life evolving and not destroying itself. At this point we have a sample of only 1. We don't know how long it takes to detect earth from the average distance any civilizations are separated from each other in the universe. We don't know how long it takes for a typical civilization to get around to visiting enough planets to have a high chance of visiting earth should that civilization evolve at a specific distance from earth. It seems unwarranted to extrapolate from such slim collection of data a position so far from neutrality as "infinitesimal". Also, exactly how much is infinitesimal? Is it larger than 1 when multiplied by 6e18?

[lilyannerose]

'Saerules' pid='110393' dateline='1292585117']
That we haven't yet been carted off by slave traders, and also haven't been exterminated for our resources and/or planet, admittedly makes me feel more safe in regards to the galaxy.

Wasn't it Sitchin who claims that he translated some tablets and that we, The Adama, are nothing more than the product of some tweaked DNA in order to produce a race of slave labor for some lazy celestial overlords? I have to admit that it's more fun than being the product of some inferior deity who created us for nothing other than to have something to kneel and bow to their celestial radiance. (Has anybody else ever seen those alleged tablets of Sitchin?) IOW, We are The Cylons!

While I don't know if ETs have ever landed or would land I'm going to stay in the gray of the idea, but who is to say that ETs would not be interested in something other than humans in terms of an interest in this planet? Just as I won't inflate our "importance" neither will I inflate the old depreciate humanity in terms of holding interest for other possible life. To support one thought over the other makes no sense as we have no concept of how other species would think, what their priorities would be, nor what their needs would be.

Frankly, I like the "wondering" of it all aspect!

[thesummerqueen]

While I don't know if ETs have ever landed or would land I'm going to stay in the gray of the idea, but who is to say that ETs would not be interested in something other than humans in terms of an interest in this planet? Just as I won't inflate our "importance" neither will I inflate the old depreciate humanity in terms of holding interest for other possible life. To support one thought over the other makes no sense as we have no concept of how other species would think, what their priorities would be, nor what their needs would be.

Frankly, I like the "wondering" of it all aspect!

There was another interview on Amateur Scientist Podcast with an astronomer, I think, who was discussing where we were in terms of space travel and other races who would be capable of it...basically we're like ants if you compare them to us. Maybe some would be interested in studying an inferior life form, but most would probably just ignore us as a minor pest. I'll have to find that one.

[Anomalocaris]

I am not assuming we are the first. But it is a different kind of narcissism to assume we or our planet warrants any special attention, or that any who came before us would be motivated in such a way that they would visit us.

Earth is reasonably suited to most of the life I am aware of, and earth has many resources, not to mention that our race is suitable for a number of forms of manual labor, with enough intellectual capacity to perform such reasonably complex tasks as language and science. I'd say we make good cheap slave labour, and there's 7 billion of us, and we have little difficulty breeding more. That we haven't yet been carted off by slave traders, and also haven't been exterminated for our resources and/or planet, admittedly makes me feel more safe in regards to the galaxy.

---

I heard an interview with an archaeologist who said he hears the arguments like that for Atlanteans and says "where is their garbage then?" That we just don't see anything in the archaeological record that can't be identified with one particular known historical group. If the aliens were here, either it was way before humans were around, or they were the neatest bastards to walk the face of the earth.

Strange that i interpreted that to mean that the aliens were all gay >_>

Earth is suited to most life you know simply because those life for which earth is not suited would either be extinct or never evolved. Aliens probably never had anything to do with the earths, so no need to suppose we or our planet suit them. While being slaves to aliens might be titillating to us, it may not be titillating to them, we eat a lot, shit a lot, talk a lot, need lots of water and air to stop from dropping dead and making a stinking mess . We can barely carry our own body weight, we lie around doing nothing like sacks of potatos for a third of each day, we can't crawl up walls, we can't breath water, we not good at thinking straight, we are fractious. If their body plan isn't like ours, which it almost certainly isn't, then they can't even use us for sex in a pinch, gay or straight. So We are generally not good for anything, and smart aliens with space travel technology can do better with gadgets.

[lilyannerose]

Aliens are life you are unaware of, so no need to suppose we or our planet suit them. While being slaves to aliens might be titillating to us, it may not be titillating to them, we eat a lot, shit a lot, talk a lot, need lots of water and air to stop from dropping dead and making a stinking mess . We can barely carry our own body, we lie around doing nothing like sacks of potatos for a third of each day. we not good at thinking straight, we are fractious.

When the Anunnaki return as Nibiru returns in 2012 they'll have the remote control and will switch on all of our junk DNA! They'll switch off our self loathing fail safe DNA (after all if left to our devices we might think we actually run the joint and do things like punch big holes in the ocean floor and kill parts of their oceans), our I need to serve my master DNA will be switched on, thereby freeing us from our constant and exhaustive search for the answer to the meaning of our lives.

[Welsh cake]

It appears Jupiter like planets are very common in planetary systems. Very large Jovian planets are to be found in majority of the planetary system we know of. So I think the odds of a planetary system having large planets to sweep up debris from primodia disk and deflect later comets is high.

That much is apparent from looking at systems such as 55 Cancri, but that's not the point I was making. The point was, where there are also terrestrial planets in addition to gas giant whose mass acts like a gravity well that offers some means of protection from the onslaught of celestial bodies with rogue orbits, now currently only four planetary systems including Cancri and our Solar System are known to consist of at least five planets.

Also, I think you unnecessarily narrow the range of planets that might harbor life. There is no reason to suppose, for example, that large Jovian planets with long lasting internal heat sources can not support life in it's own atmosphere without being in the goldilock zone.

That's because we don't know if such life-forms can actually exist, asserting anything else at this point is pure speculation. I've heard all sorts of pseudo-science-fiction hypotheses that life may thrive inside stars! I can't really dismiss it as 'utter nonsense', as tempting as that is, since its plausible the cosmos may harbour extraterrestrial life in ways and forms which we've not yet observed or anticipated, but until we do discover them, we've no reason to believe otherwise. What we do know to a fairly high degree of certainty is that life can come from non-life on terrestrial planets such as Earth. The whole goal of proposed projects such as the Terrestrial Planet Finder is to try and find extrasolar planets like Earth that are more likely to harbour alien life-forms, than say a black hole, or a hypergiant star without a planetary system even, or a runaway planet and so on and so on.

As to the chances of intelligent life evolving and not destroying itself. At this point we have a sample of only 1.

I think you'll agree we've very nearly destroyed ourselves quite a few times (and still might do so in the near-future when overpopulation takes hold and our resources start to run out); bearing in mind internal threats such as war and conflict were being used as just an example.

We don't know how long it takes to detect earth from the average distance any civilizations are separated from each other in the universe. We don't know how long it takes for a typical civilization to get around to visiting enough planets to have a high chance of visiting earth should that civilization evolve at a specific distance from earth.

Given the current age of the universe, our existence as a species and current progress at space exploration, the answer is obvious, they would have to evolve and develop the interstellar travel technology at an exponential rate than our own.

It seems unwarranted to extrapolate from such slim collection of data a position so far from neutrality as "infinitesimal". Also, exactly how much is infinitesimal? Is it larger than 1 when multiplied by 6e18?

It was used as an expression, you'll appreciate that I did not state it was "impossible", nevertheless the odds, like you and me being born from an unbroken chain of life going back millions of years and having this discussion over a telecommunications network developed in the space of a century, are also incalculably small.

[Anomalocaris]

That much is apparent from looking at systems such as 55 Cancri, but that's not the point I was making. The point was, where there are also terrestrial planets in addition to gas giant whose mass acts like a gravity well that offers some means of protection from the onslaught of celestial bodies with rogue orbits, now currently only four planetary systems including Cancri and our Solar System are known to consist of at least five planets..

Most of our planetary discoveries have been made by finding cyclic doppler shifts in star light. It can be deduced even a priori that a major sampling biase in favor of finding solar system dissimilar in configuration to our own would result from the choice of method:

1. Planets close to its star are easier to detect because of faster and stronger doppler cycles they induce in the light from their star as observed from earth.
2. Big Planets are easier to detect because of faster and stronger doppler cycles they induce in the light from their star as observed from earth.
3. Therefore most of the planetary system we have detected contained big planets orbiting very closer to their primary stars.

So it is not surprising that even if planetary systems with configuration similar to our own is common, they would not be common in the result of our initial search for extra-solar planets.

That's because we don't know if such life-forms can actually exist, asserting anything else at this point is pure speculation. I've heard all sorts of pseudo-science-fiction hypotheses that life may thrive inside stars! I can't really dismiss it as 'utter nonsense', as tempting as that is, since its plausible the cosmos may harbour extraterrestrial life in ways and forms which we've not yet observed or anticipated, but until we do discover them, we've no reason to believe otherwise. What we do know to a fairly high degree of certainty is that life can come from non-life on terrestrial planets such as Earth. The whole goal of proposed projects such as the Terrestrial Planet Finder is to try and find extrasolar planets like Earth that are more likely to harbour alien life-forms, than say a black hole, or a hypergiant star without a planetary system even, or a runaway planet and so on and so on...

We don't need black holes or inside of stars. Even life evolved on earth will likely be able to tolerate conditions outside the goldilock zone. For example, the subsurface ocean of Europa probably contain all that is necessary to replicate conditions near hydrothermal vents on earth's ocean floor, where life on earth likely first originated on earth. In our own solar system, there are probably many more moons outside the goldilock zone that could either support life currently found earth than there are planets in the goldilock zone. One could debate whether life arising there or planted there has good chance of evolving towards high complexity, but I am unwilling to venture a strong opinion on that.

I think you'll agree we've very nearly destroyed ourselves quite a few times (and still might do so in the near-future when overpopulation takes hold and our resources start to run out); bearing in mind internal threats such as war and conflict were being used as just an example....

No, I don't agree. Human can cause massive depopulation, civilizational regression, and loss of learning and science. We've not come close to pulling ourselves up by the roots or had our roots pulled out by femine, over population, etc. I also think we are unlikely to be able to actually either completely exterminate ourselves or arrange things for survivors so that no advanced civilization will be reborn in the geologically relative near future. Genetic studies suggests ancesters of native Americans who came to America numbered no more than a few hundred. Yet in 10,000 years they populated 2 continents and developed cultural sophistication perhaps only a millenium or two behind the old world. I think it will take a very large natural catastrophic event like an asteroid collision coinciding with a period of very deep civilizational decline to bring about human extinction.

Given the current age of the universe, our existence as a species and current progress at space exploration, the answer is obvious, they would have to evolve and develop the interstellar travel technology at an exponential rate than our own. .

A reasonable view, but not the only one.