Stephen Hawking Warns Against First Contact

[Perd Hapley]

Why else would you call the earth the center of the universe, if not for that? 

Did I? 

To quote Vernor Vinge (speaking through a very advanced fictional civilization),
Why would we assume that the Earth is somehow special -- given the very limited data we have to go on about exoplanets, and even less data on Earth-like exoplanets -- unless, of course, we've already made up our minds that we WANT Earth to be special, because our philosophy/religion says so?

Let's say I did falsely assume that Earth was "special."  This looks like pride to you?  Why?  What would I have to be proud about? 
 
Just for what it's worth, as a Christian, I don't think my religion says that earth is special.  So far as I know, there is no Christian doctrine or teaching about other planets or who might live there. 

[mellestad]

Did I?  

No one said you did.  You asked a question, I answered it.  "You" means "whomever is making the statement."

[mellestad]

Let's say I did falsely assume that Earth was "special."  This looks like pride to you?  Why?  What would I have to be proud about?  

Also, if you wouldn't mind, you might answer your own question by answering the question I asked above:  Why else would you call the earth the center of the universe, if not for that?

Edit:  When something is "special" that usually means there is some pride attached to that fact, at least in common usage. 

[tyme]

Just for what it's worth, as a Christian, I don't think my religion says that earth is special.  So far as I know, there is no Christian doctrine or teaching about other planets or who might live there.  

How about the fact that Jesus died (allegedly for our sins) on Earth and was (allegedly observed as being) allegedly resurrected on Earth.  That makes Earth pretty darned special, in my estimation, according to Christianity.

[Headless Thompson Gunner]

Riddle me this.  If it's so probable that life exists elsewhere, why have we not seen any evidence of it?  If foreign life is probable, then our rapidly increasing abilities to observe off-planet locations should turn up growing evidence of off-planet life.  On the other hand, if there is no other life out there, then our growing ability to observe off-planet would necessarily be met by continuing lack of evidence of foreign life.

So far the no-foreign-life scenario is the one that's proving out.

Back at the turn of the century (last century, 1900) it was whimsical to imagine that there were people living on the moon, Mars, and Venus.  At the time our lack of knowledge of these places enabled us to reasonably conjecture that life could exist on them.  Now that we've explored and observed these places in some detail, it no longer makes much sense to presume life exists there.

I wonder about the trend continuing.  Being able to observe our nearby planets has ruled out life there.  Soon we'll be able to make meaningful observations of planets in foreign solar systems.  If we continue to fail at turning up evidence of life even as our knowledge of remote places grows, our own little existence becomes increasingly lonely (or "special", if you prefer). 

Obviously this would change on a dime the moment we learn some new tidbit pointing to the existence of foreign life.  But the longer we go without uncovering anything, the less likely it becomes that anything exists.

[gunsmith]

There was a pretty good sci fi story I read once, about finding a civilization that was wiped out
by a supernova, and they left really good devices ( like movies I guess ) so that some star travelers could find them,  ( safe bet us humans because we see )  and it turned out the supernova was the event that led the three wise men to find baby Jesus. It really bummed out the main protagonist. Not me though, I figure they were asking for it. I cant remember the author. Probably Clarke or Niven

[zahc]

I don't think it matters if there is life 'out there', or what the probability is.

It doesn't matter because if it's 'out there' it's so far away that it's completely irrelevant. It's like the tree-falling-in-woods-with-nobody-around argument. Since (I feel) it couldn't possibly matter if there are populated exoplanets, then, I would rather ponder other things that do (or could) possibly matter.

[AJ Dual]

There was a pretty good sci fi story I read once, about finding a civilization that was wiped out
by a supernova, and they left really good devices ( like movies I guess ) so that some star travelers could find them,  ( safe bet us humans because we see )  and it turned out the supernova was the event that led the three wise men to find baby Jesus. It really bummed out the main protagonist. Not me though, I figure they were asking for it. I cant remember the author. Probably Clarke or Niven

Ah yes, the main character telling the story as a narration/diary sort of style was a Jesuit priest attached to the survey mission.

The civilization was was "perfect" as far as they could tell, no war, no hunger, no want, safety and justice/peace for all. And it created a rather deep crisis of faith for the poor priest.

Ah... here it is:


http://en.wikipedia.org/wiki/The_Star_%28short_story%29

Although instead of nihilist, it could just re-iterate the theme of salvation. One could argue that God sacrificed his "perfect" civilization that was without sin to bring about the sacrifice of himself/his son who was perfect and without sin... for the ones who needed it.

(shrug)

Kind of trite by today's SF standards, but pretty heavy/edgy for Arthur C. Clarke and the time when he wrote it.

[Perd Hapley]

How about the fact that Jesus died (allegedly for our sins) on Earth and was (allegedly observed as being) allegedly resurrected on Earth.  That makes Earth pretty darned special, in my estimation, according to Christianity.

That's one way of looking at it, but as I said, I don't know of any such teaching in Christianity, that Earth is special because Christ was killed and resurrected here.  Maybe some Christians believe that...

On the other hand, how do we go about comparing that with the way God has dealt with the supposed aliens?  Does He deal with them differently?  Does He treat them better or worse?  Is Earth only "special" because it was the one planet that chose to rebel?  (a la, C.S. Lewis)  Is it possible Christ was doing the same thing (gettin' killed and resurrected), at the same time, on forty-thousand other planets? 

[RocketMan]

are we sure there is intelligent life on THIS planet?

Yes, but I'm going home next Tuesday.

[BrokenPaw]

Riddle me this.  If it's so probable that life exists elsewhere, why have we not seen any evidence of it? 

For the same reason that, though it's pretty probable that a meteorite has hit the Earth today, even a very careful and thorough inspection of every single square millimeter of your front yard is unlikely to turn up any evidence of it.

[MechAg94]

That's one way of looking at it, but as I said, I don't know of any such teaching in Christianity, that Earth is special because Christ was killed and resurrected here.  Maybe some Christians believe that...

On the other hand, how do we go about comparing that with the way God has dealt with the supposed aliens?  Does He deal with them differently?  Does He treat them better or worse?  Is Earth only "special" because it was the one planet that chose to rebel?  (a la, C.S. Lewis)  Is it possible Christ was doing the same thing (gettin' killed and resurrected), at the same time, on forty-thousand other planets? 

I would say that Earth is special in the Bible since most of the Bible focuses on events taking place here.  I would also say that the Earth is pretty damn special to all humans since we all still live here and were created here.  Should we instead think Pluto or some other planet is special?  Why?

Beyond that, is the Earth special to the Universe?  I don't know and it doesn't really matter.  If 3 billion aliens lived on a planet in some other galaxy, would they care about Earth?  Do I care what they think?  No.

[Tallpine]

I don't think it matters if there is life 'out there', or what the probability is.

It doesn't matter because if it's 'out there' it's so far away that it's completely irrelevant. It's like the tree-falling-in-woods-with-nobody-around argument. Since (I feel) it couldn't possibly matter if there are populated exoplanets, then, I would rather ponder other things that do (or could) possibly matter.

Ah, that's what Professor Drummond said

[Headless Thompson Gunner]

For the same reason that, though it's pretty probable that a meteorite has hit the Earth today, even a very careful and thorough inspection of every single square millimeter of your front yard is unlikely to turn up any evidence of it.

Except you wouldn't be looking in your front yard, you'd be looking at the sky.  Even with the naked, and even without specifically searching it out, you're likely to notice evidence of meteorites standing in your front yard some day.  And that's without any powerful tools or a deliberate search.  Put some real effort into it and you'll see lots of evidence of meteorites.

[mellestad]

Except you wouldn't be looking in your front yard, you'd be looking at the sky.  Even with the naked, and even without specifically searching it out, you're likely to notice evidence of meteorites standing in your front yard some day.  And that's without any powerful tools or a deliberate search.  Put some real effort into it and you'll see lots of evidence of meteorites.

The point is scale.  Us looking, really, really hard for alien life is equivilent to using a garden trowel to check for space rocks in your back yard.

Honestly it is worse than that, because the scale of earth vs. universe is far greater than back yard vs. earth.  Even the best we can do, like SETI, probably only has a chace to detect signals if they originated in our immediate area.  At our best, we can only check for neighbors.

[MechAg94]

Not to mention the obvious as well, but aside from signals, we can't see anything small enough to tell us what exists out there with regard to life.  We can only see planets due to the way they affect the light from there suns. 

I think we have a long way to go before we answer questions like that.

[mellestad]

Not to mention the obvious as well, but aside from signals, we can't see anything small enough to tell us what exists out there with regard to life.  We can only see planets due to the way they affect the light from there suns. 

I think we have a long way to go before we answer questions like that.

Yup.  Although I think I remember an article that mentioned the Hubble actually 'saw' an exoplanet a while ago, after it got upgrade.

[Headless Thompson Gunner]

The point is scale.  Us looking, really, really hard for alien life is equivilent to using a garden trowel to check for space rocks in your back yard.

Honestly it is worse than that, because the scale of earth vs. universe is far greater than back yard vs. earth.  Even the best we can do, like SETI, probably only has a chace to detect signals if they originated in our immediate area.  At our best, we can only check for neighbors.

Scale is precisely the point.  It's a lot easier to believe in extraterrestrial life when you don't know anything about extraterrestrial areas.  As our sphere of observation grows, and as we further learn that no other life exists with in it, the probabilities diminish.  The scale of the lifelessness out there only grows as we learn more and more.

And SETI was actually something I had in mind.  SETI has been able to do a considerable amount of searching in our nearby time/space and have come up with a convincing zero in terms of technological life.  Obviously we haven't searched the entire universe yet, but our sphere of awareness is growing, and the scale of the emptiness grows along with it.

I guess I think that if foreign life was so very probable, that it would be similarly probable that we'd notice something about it.  If the universe is so infinite and other life is so probable, surely someone out there would have put up a cosmic neon sign saying "look at me", or stumbled across us by mistake, or simply revealed their presence through no overt action of their own.  We know this is not the case.

To reconcile the probability of foreign life with the growing evidence for no life requires that the probability not be arbitrarily high as some seem to assume, but rather it must be more of a Goldilocks situation: high enough to exist somewhere while not being so high that it led to life that we'd notice (or that would notice us).

[mellestad]

Scale is precisely the point.  It's a lot easier to believe in extraterrestrial life when you don't know anything about extraterrestrial areas.  As our sphere of observation grows, and as we further learn that no other life exists with in it, the probabilities diminish.  The scale of the lifelessness out there only grows as we learn more and more.

And SETI was actually something I had in mind.  SETI has been able to do a considerable amount of searching in our nearby time/space and have come up with a convincing zero in terms of technological life.  Obviously we haven't searched the entire universe yet, but our sphere of awareness is growing, and the scale of the emptiness grows along with it.

I guess I think that if foreign life was so very probable, that it would be similarly probable that we'd notice something about it.  If the universe is so infinite and other life is so probable, surely someone out there would have put up a cosmic neon sign saying "look at me", or stumbled across us by mistake, or simply revealed their presence through no overt action of their own.  We know this is not the case.

To reconcile the probability of foreign life with the growing evidence for no life requires that the probability not be arbitrarily high as some seem to assume, but rather it must be more of a Goldilocks situation: high enough to exist somewhere while not being so high that it led to life that we'd notice (or that would notice us).

What signal could a civilization put out that would reach across a galaxy, much less the universe?

I understand your point, but our sphere of observation is so tiny I don't see how that invalidates his original analogy.

Also, as mentioned earlier, the distances and expense involved in extrasolar (much less extragalactic) travel means there is no reason to assume alien life would ever leave their own system.

Space is so vast there is a good chance that meaningful interstellar travel is a practical impossibility.

[red headed stranger]

Sounds like HTG is talking about Fermi's Paradox:

http://en.wikipedia.org/wiki/Fermi_paradox

At this point I don't buy it, because we have observed so very little of the universe for it to be valid just yet. 

Moreover, in our study of our own planet, we have been finding more life than we previously thought possible, so it seems to me that we still haven't come to a reasonable conclusion as to what environment is conducive to life.  I think this is also due the fact that we haven't gather nearly enough info to make an informed decision. 

[AJ Dual]

Sounds like HTG is talking about Fermi's Paradox:

http://en.wikipedia.org/wiki/Fermi_paradox

At this point I don't buy it, because we have observed so very little of the universe for it to be valid just yet. 

Moreover, in our study of our own planet, we have been finding more life than we previously thought possible, so it seems to me that we still haven't come to a reasonable conclusion as to what environment is conducive to life.  I think this is also due the fact that we haven't gather nearly enough info to make an informed decision. 

Further complicating Fermi's Paradox, is Von Neuman self-replicating probe idea. A species need not explore the galaxy, but make just one probe that contains sufficient robotic machinery to construct 2 copies of itself from local resources in the next star system over, and send them off, and so on.

http://en.wikipedia.org/wiki/Self-replicating_spacecraft

Even at 10% of c, with reasonable turnaround times, acceleration/braking, such probes would fill the galaxy in a million years or so. So out of 400 billion stars in the history of the Milky Way, only ONE other race needed to do this, and our Solar System would have a probe in it, or evidence of it's mining activities in the asteroid belt... whatever.

So aside from the SETI "great silence", I think that at a minimum, sentient technological civilizations are both very rare, and perhaps the ones that survive grow beyond even the desire to create Von Neuman probes. (Yes, I'm a broken record, bringing in Technological Singularity again...)

[BrokenPaw]

I actually did the math, because I figured someone would call me out on the whole looking-in-your-yard-for-meteorites.  It turns out I was wrong.

To date, the most distant exoplanet discovered is ~6500 parsecs away.  If we use that number as the radius of a sphere we can say we've 'investigated' (which is being pretty generous), and we assume the universe is a sphere 15 billion light years across (again, a rough number for the sake of argument), then trying to draw conclusions about what life could be in the universe based upon what we have observed is, in terms of scale, the equivalent of trying to extrapolate what life might exist elsewhere on earth by examining a patch on your yard that is 2.23 square inches big.

So I was off by an order of magnitude or five.

[tyme]

A great but old analysis of Fermi's Paradox: http://hanson.gmu.edu/greatfilter.html

While there might be a great filter that limits our future capabilities, I think there are plenty of other explanations, so I'm not particularly worried.

A few reasons why life may exist but we haven't detected it:

- It's not very advanced.  Other civilizations at our level couldn't detect us without being very lucky or very close to us.

- The kind of engineering projects advanced civilizations engage in may look like natural phenomena.

- Even for an advanced civilization, in another galaxy and certainly in a galaxy beyond the local group, it would take a lot of energy and maybe logistics to set up omnidirectional communication... and that could just as easily attract unwanted attention from an equivalent or even more advanced competing civilization.

- Maybe they've discovered FTL communication and don't even bother with light or sublight comm anymore because the kind of civilizations who use those methods are uninteresting and very far from achieving technological parity: not interesting and not a threat.

- Advanced civilizations might use the communication media we do, but they may not want to talk to us, even though they're perfectly capable.

- Maybe we're a colony of theirs they seeded with bacterial life, possibly including teraforming, and are leaving us alone on purpose.

- Maybe we're in a pocket universe that some advanced civ designed as an experiment, and they leave everything pretty much pristine.  Note that this scenario would be impossible to distinguish at our current level of tech from any arbitrary religion.  However, such life would not be Gods; they would be subject to any physics constraints that exist in the parent universe.

- The idea that advanced civilizations desire explosive growth could be false.  Perhaps they find other ways to deal with their growing populations that don't include taking over their existing galaxy/universe; for instance, assuming it's possible, perhaps they would rather create pocket universes and inhabit those, leaving the parent universe nearly pristine.  Maybe they're happy with zero population growth so they don't need more real estate of any kind, and their energy harvesting method is not readily observable to us.  Maybe they have AIs, nanotech robots, etc. doing most of their physics research and exploration and chores for them; then they wouldn't need large populations for anything.

[GigaBuist]

I guess I think that if foreign life was so very probable, that it would be similarly probable that we'd notice something about it.  If the universe is so infinite and other life is so probable, surely someone out there would have put up a cosmic neon sign saying "look at me", or stumbled across us by mistake, or simply revealed their presence through no overt action of their own.  We know this is not the case.

Dude, it'd take 15 billion years for a signal to reach across the universe.  Humans have only been doing this "radio" stuff for about 70 years. We've only been looking for signals from outer space for maybe 30 years.  We're pretty new at this game.  Heck, humans are pretty new when you think about it.  We've been here for  about 200k years.  If we die out in the next 100k we're still just a blip on the radar compared to the life of the universe.

It's possible that an intelligent species 100 light years away rose up and managed to kill themselves while we were still scraping at dirt.  We'd never know about them though.  Anything they transmitted would have passed us by long before we learned to work with radio waves.

To us it seems like we're a pretty advanced species but we wasted a lot of time in getting here. It wasn't until about 6,000 years ago that we learned to cook food. After that things really started to pick up.  We got smarter through better nutrition and we created complex languages, religions, government, simple tools, etc.  Then the tools got more complex.  Engines, planes, and finally flight into space.

The cool thing is that we're getting faster and faster at developing new technology. It took us 194k years to figure out that we should cook food. 700 years ago it took a government backed effort to go from Europe to North America.  Today you can do it for a thousand bucks and at 450mph in a jet.  We went from flightless to breaking the sound barrier in a jet in 60-ish years.  And then we went and tossed people up to the moon.

What are things going to look like 700 years from now?  I'd wager they'll be a whole lot different.  North America will no longer be the "new world" -- it'll be Mars or the moon, or maybe something out in Alpha Centauri.  Or maybe we'll have colonies living in nuclear powered craft akin to a submarine of today, but light years away as humans raise generation after generation on space ship that's buggering along at 90% of light speed.

I believe other intelligent beings are out there but we haven't found them yet. If I'm wrong, well, that doesn't really matter.  Mankind will continue to explore space because it's what we do.  If I'm right we'll find it.  If I'm wrong we'll just have more technology at our disposal to keep us alive and spread ourselves around the galaxy a bit.

[roo_ster]

I am indifferent to the possibility of the existence of life elsewhere, but I find it odd that materialists reject the data collected so far and insist on convoluted schemes where the data collected is irrelevant.  Ockham's Razor need not apply.

Reminds me of young-earth creationsists.  The data says one thing, but their hope & faith requires an alternate explanation.  Every time new data is uncovered, the explanation must be modified until it occurs that what is required is an unfalsifiable explanation resting on some non-empirical basis.  For creationists, it is revelation of the word of God in the Bible.  For materialists it is the magic wand of time (& space, for this particular question).

An empiricist would craft his theory on existing data.  Today, the best data shows zero evidence of life off of Earth.  HTG nails it: the more we search, at greater ranges and with greater sensitivity, the more space we determine is lifeless beyond our planet.  If some data in the future shows evidence of life elsewhere, then craft a theory that best fits the data.

It ain't that hard, unless one is trying to make the facts fit one's preconceived notions.

A fine example is Ptolemy's geocentric cosmology.  We now know it to be a faulty model, but it was better than most until Copernicus came along 1300 years later.  He used the tools & data he had at hand and crafted a model of the universe that was very usable.  Later refinement allowed accurate prediction of the planets' location in the sky, despite is errors.  Compare that to other contemporary cosmologies that rejected contemporary data and substituted convoluted schemes.