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Stephen Hawking: Why Isn't the Milky Way "Crawling With Self-Designing Mechanical or Biological Life?"


In his famous lecture on Life in the Universe, Stephen Hawking asks: "What are the chances that we will encounter some alien form of life, as we explore the galaxy?"

If the argument about the time scale for the appearance of life on Earth is correct, Hawking says "there ought to be many other stars, whose planets have life on them. Some of these stellar systems could have formed 5 billion years before the Earth. So why is the galaxy not crawling with self-designing mechanical or biological life forms?"

Why hasn't the Earth been visited, and even colonized? Hawking asks. "I discount suggestions that UFO's contain beings from outer space. I think any visits by aliens, would be much more obvious, and probably also, much more unpleasant."

Hawking continues: "What is the explanation of why we have not been visited? One possibility is that the argument, about the appearance of life on Earth, is wrong. Maybe the probability of life spontaneously appearing is so low, that Earth is the only planet in the galaxy, or in the observable universe, in which it happened. Another possibility is that there was a reasonable probability of forming self reproducing systems, like cells, but that most of these forms of life did not evolve intelligence."

We are used to thinking of intelligent life, as an inevitable consequence of evolution, Hawking emphasized,  but it is more likely that evolution is a random process, with intelligence as only one of a large number of possible outcomes.

Intelligence, Hawking believes contrary to our human-centric existece, may not have any long-term survival value. In comparison the microbial world, will live on, even if all other life on Earth is wiped out by our actions. Hawking's main insight is that intelligence was an unlikely development for life on Earth, from the chronology of evolution:  "It took a very long time, two and a half billion years, to go from single cells to multi-cell beings, which are a necessary precursor to intelligence. This is a good fraction of the total time available, before the Sun blows up. So it would be consistent with the hypothesis, that the probability for life to develop intelligence, is low. In this case, we might expect to find many other life forms in the galaxy, but we are unlikely to find intelligent life."

6a00d8341bf7f753ef011570b065d4970c-320wi Another possibility is that there is a reasonable probability for life to form, and to evolve to intelligent beings, but at some point in their technological  development "the system becomes unstable, and the intelligent life destroys itself. This would be a very pessimistic conclusion. I very much hope it isn't true."

Hawkling prefers another possibility: that there are other forms of intelligent life out there, but that we have been overlooked. If we should pick up signals from alien civilizations, Hawking warns,"we should have be wary of answering back, until we have evolved" a bit further. Meeting a more advanced civilization, at our present stage,' Hawking says "might be a bit like the original inhabitants of America meeting Columbus. I don't think they were better off for it."

Posted by Casey Kazan.

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This is the third in a three-part series on Stephen Hawking's views on life in the universe:

Stephen Hawking: "Humans Have Entered a New Stage of Evolution"
Stephen Hawking: "Asteroid Impacts Biggest Threat to Intelligent Life in the Galaxy"

Related Galaxy posts:

The METI Controversy (Revisited) : Should Detection by an Exo Civilization Be Viewed as a Threat?

The 10,000 Year Explosion: Has Human Civilization Turbo Charged Evolution?
Homo Sapiens -The "Time Travelers" -A Galaxy Classic
“Hyper-Speed” Evolution Discovered
Bringing Ancient Human Viruses Back to Life: A Jurassic Park or Salvation?

Immense Journey



you'd have to be stupid/steven hawking to believe there isn't intelligent life other than our own in the universe.

"you'd have to be stupid/steven hawking to believe there isn't intelligent life other than our own in the universe."

Uh... Nowhere does it say Steven Hawking "believes" we are the only intelligent life in the universe. He states it is one possibility. Belief is a strong word. You should learn to read better before posting such comments.

"you'd have to be stupid/steven hawking to believe there isn't intelligent life other than our own in the universe."

Let's work on the support showing adequate intelligent life here, first, yeah?

... maybe truely intelligent life doesn't act the way humans do?

"For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much - the wheel, New York, wars and so on - whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man - for precisely the same reasons." -
The Hitchhiker's Guide to the Galaxy

I think you only have to watch a wildlife documentary and see the spectacular variety of life on Earth (often in environments so hostile we'd previously thought nothing could live) to conclude that where ever life of some form is possible, it may be inevitable.

I favour the hypothesis that the universe is probably teaming with life and that our surveys so far are barely a drop in the ocean.

Another though occurs too. I don't subscribe to the idea of little green men in flying saucers. The idea that a super-advanced species would travel the gulf of space only to steal cows (or crash their ship) is pretty laughable.

... but I wonder could we even perceive the existence of a more advanced form of life? A species thousands, millions even billions of years more advanced than us would be so different. Would we be like ants trying to comprehend the human world?

Very similar ideas to those that I put forward in my two-part discussion on the possibility of alien life.

I think life is out there and is flourishing all over the universe. But intelligent life is (as Hawking says) a much more difficult proposition...

So what about the intelligent communications and scripted messages pressed into the fields at Milk Hill near Avebury and Alton Barnes in southern England this summer?
There appear to be some forms of intelligent language or code in the energy imprints bent in the living plants, but can anyone read them?
Please take a look with an open mind and consider that the "impossible" might possibly be happening right in Stephen's backyard.
Images and information found at:
-- and many other sites.
Help! Are these pleasant messages or warnings?
Who can read them and what might they say?

Ezikiel discribes a visit of alians in the bible, 'and they ascended to heavon on a pillar of fire' reminds me of the space shuttle.

I consider it as if we're sperm trying to perceive what life as a human being would be like. From our perspective as human beings, we can't even imagine what a more advanced intelligence would be like, just as the sperm couldn't possibly imagine what a human is like. Until we, as a race make that journey to the next step of existence we're just sitting in a universal ballsack.

It would be cool if we're the first to colonize the galaxy. I'd rather be Columbus myself... given the choice.

The guy who wrote this article is comma-happy.

There is another possibility, one that Hawking didn't mention...

That the universe is teeming with life, that it there millions, even billions of intelligent and technological civilisations in the Galaxy... and the reason none of them has visit here, or even contacted us, is because Earth, and humans, are basically rather boring. That we are nothing at all special in comparison.

Not very flattering to our ego though...

comma comma down doo bee doo bee down .............. :)

Just the sheer numbers make it very likely that other life exists not only in the universe or our galaxy but somewhere in our inter-stellar neighborhood. As a matter of fact microbial life probably exists in our solar system. Even though we admitted the earth revolves around the sun some time ago human still have a very earth-centered point of view when it comes to looking at the universe which is rather silly given the size of it.

"Why hasn't the Earth been visited, and even colonized? Hawking asks."

That seems to preclude the idea that we may be the colonizers.

Just a few observations/ideas:

Stephen Hawking says: "I discount suggestions that UFO's contain beings from outer space. I think any visits by aliens, would be much more obvious, and probably also, much more unpleasant."

He has set up a VERY narrow lens through which to explain/interpret his thesis. There are many other possibilities (some of which we may not even imagine from our perspective). If aliens are are already here or at least visit what makes him think they would be much more obvious or unpleasant?

First let's assume they haven't always been here; for they could have played a much larger role in our historical/evolutionary development than we realize. If they only visit, they obviously would have technology to remain hidden beyond our wildest imaginations. There could also be more than one race visiting/interacting here on Earth. In that case, they would likely have a treaty excluding direct official contact. Also, if their interest is primarily scientific, it is likely that they would attempt to minimize their impact/influence on what they are studying. In short, there are many, many possibilities.

He also seems to lean toward the assumption that alien visitors will be hostile towards us. Again, this is a strong assumption that alters all further hypotheses. He may be right, and there is some anecdotal evidence to support this. But again, reality may be much more complicated--especially if there are more than one race involved.

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Someone left God out of the equation.

it's just amazing...
i'm speechless

Whoever wrote this article needs to learn the appropriate placement of commas. For example, the following sentence:

"I think any visits by aliens, would be much more obvious, and probably also, much more unpleasant."

should read:

"I think any visits by aliens would be much more obvious, and probably also much more unpleasant."

We don't have much evidence, and so far that evidence is limited to one planet, so we are basically guessing. The comment that we might be in the condition of ants with regard to humans makes sense, though.

From the little bit of evidence we do have, there appear to be at least three "intelligent" species on this planet, and there is rapidly burgeoning evidence that problem-solving intelligence is widespread among at least endothermal species, so the thesis that "intelligence" is a rare result of evolution seems unlikely.

I'd suggest that evolution tends to increasing complexity in a logarithmic progression--which would account for the fact that the progression from unicellular to multicellular life took so long--one would expect succeeding stages to be shorter and shorter--and that complexity rather naturally tends to what we describe as intelligence.

I, think, that, photo, of, Hawking, was, 'shopped

“Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.” — Calvin & Hobbes

The aliens that make the crop circles must be very small or very low in the power department , as we in B.C. have never witnessed a tree circle. This could be used to calibrate their probable size ,lol .On the subject of God . If one can believe in the invisible man in the sky. Whom knows and see's all . Then why not little crop circling green men . We have just as much evidence for either .

Stephen Hawking is obviously much smarter than I am, so I hesitate to question his logic. However, there are a couple of things that I think he is over looking. First off, timing is everything. The Universe is roughly 13 billion years old. The Earth is about 5 billion. Our ability to understand the Universe is only a few hundred years old at most (you can argue that we still don't really understand it).

Who is to say that very advanced civilization did not exist a million years ago and has, for some reason, died out or is no longer looking outside its home planet for some reason.

Second, you can not escape the fact that the distance between stars in the galaxy/universe is very large. Intelligent life usually requires a great deal of resources to stay alive. Therefore, it is quite possible that it is very difficult for intelligent beings to travel the distances needed to visit other stars (at least not very often). It could be that intelligent life is fairly common, but the ability to visit other planets with intelligent life is very uncommon.

Given how pervasive life is on Earth, I find it inconceivable that it is not equally pervasive. It may be that intelligent life is uncommon, but I find that hard to believe as well since there are many species on Earth that are capable of more evolved thought.

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