NASA Discovers Life's Building Blocks 1st Delivered to Earth By Meteorites & Comets
The Daily Flash -Eco, Space, Tech (8/19)

"The Great Silence": Why Haven't Signs of Intelligent Extraterrestrial Life Been Discovered?

Double_helix_nebula_2_3_3 "The idea that we are the only intelligent creatures in a cosmos of a hundred billion galaxies is so preposterous that there are very few astronomers today who would take it seriously. It is safest to assume therefore, that they are out there and to consider the manner in which this may impinge upon human society."

Arthur C. Clarke, physicist and author of 2001: A Space Odyssey

The world-renowned physicist Lee Smolin author of Life of the Cosmos says that what we should look for to confirm the existence of intelligent life in the Milky Way is a message left for us some time in the last several hundred million years. 

Smolin suggests that one such message might have been left in the genetic code of some living creature in the language of nucleic acid bases in the DNA, confident that the ability of living creatures to replicate DNA would keep the message relatively uncontaminated for the time scales of this order. There is a great deal of DNA in most species that does not play any biological role and varies enormously from species to species without apparent cause. The existence of this DNA is one of the puzzles of molecular biology.

The unsolved question of the existence of extraterrestrial intelligence is one of the greatest  scientific challenges that currently confronts humanity.

The Fermi paradox is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilizations and the lack of evidence for or contact with such civilizations.

The 14-billion-year age of the universe and its 130 billion galaxies and a Milky Way Galaxy with some 400 billion stars suggest that if rocky planets like Earth orbiting around small yellow stars are typical, intelligent life should be common. Using NASA's Spitzer Space Telescope, a team of scientists found that at least 20 percent, and possibly the majority (as many as 60 percent) of stars similar to the sun are candidates for forming rocky planets. The Legacy Science Program set out to determine whether planetary systems like ours are common or rare in the Milky Way. What they found is that many, perhaps even most, of the sun-like stars in our galaxy could well harbor Earth-like planets.

Dn17084-1_300 The ideal stars to support planets suitable for life for tens of billions of years may be a smaller slower burning ‘orange dwarf’ with a longer lifetime than the Sun ― about 20-40 billion years. These stars,  called K stars, are stable stars with a habitable zone that remains in the same place for tens of billions of years. They are 10 times more numerous than Sun G-class stars, and may provide the best potential habitat for life in the long run.

Nobel laureate Enrico Fermi, discussing this observation with colleagues over lunch in 1950, asked, logically: "Where are they?" Why, if advanced extraterrestrial civilizations exist in our Milky Way galaxy, hasn't evidence such as probes, spacecraft, or radio transmissions been found?

As our technologies become ever more sophisticated and the search for extraterrestrial intelligence continues to fail, the "Great Silence" becomes louder than ever. The seemingly empty cosmos is screaming out to us that something is amiss. Or is it?

Using a computer simulation of our own galaxy, the Milky Way, Rasmus Bjork, a physicist at the Niels Bohr Institute in Copenhagen, proposed an answer to the Fermi Paradox. Bjork proposed that an alien civilization might build intergalactic probes and launch them on missions to search for life.

He found, however, that even if the alien ships could hurtle through space at a tenth of the speed of light, or 30,000km a second, - NASA's current Cassini mission to Saturn is gliding along at 32km a second - it would take 10 billion years, roughly half the age of the universe, to explore a mere four percent of the galaxy.

Like humans, alien civilizations could shorten the time to find extra-terrestrials by picking up television and radio broadcasts that might leak from colonized planets. "Even then," he reported in the New Scientist, "unless they can develop an exotic form of transport that gets them across the galaxy in two weeks it's still going to take millions of years to find us. There are so many stars in the galaxy that probably life could exist elsewhere, but will we ever get in contact with them? Not in our lifetime."

The problem of distance is compounded by the fact that timescales that provide a "window of opportunity" for detection or contact might be quite small. Advanced civilizations may periodically arise and fall throughout our galaxy as they do here, on Earth, but this may be such a rare event, relatively speaking, that the odds of two or more such civilizations existing at the same time are low.

In short, there may have been intelligent civilizations in the galaxy before the emergence of intelligence on Earth, and there may be intelligent civilizations after its extinction, but it is possible that human beings are the only intelligent civilization in existence "now." "Now"  assumes that an extraterrestrial intelligence is not able to travel to our vicinity at faster-than-light speeds, in order to detect an intelligence 1,000 light-years distant, that intelligence will need to have been active 1,000 years ago.

There is also a possibility that archaeological evidence of past civilizations may be detected through deep space observations — especially if they left behind large artifacts such as Dyson spheres.

Perhaps...but in our search for life and intelligence we have to keep in mind that the Milky Way Galaxy is two or three times the age of our Solar System, so there are going to be some societies out there that are millions of years, maybe more, beyond ours, which may have proceeded beyond biology—that have invented intelligent, self-replicating machines and it could be that what we first find is something that's artificially constructed if we have the ability to recognize it as such. It may very well be that our greatest discovery will be that the very nature of alien communication will prevent our being able to communicate with it.

Posted by Casey Kazan.

Recommended:

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

Is a Dark-Energy Fueled Spaceship Possible?

Related Galaxy posts:

James Cameron & Arthur C Clarke on 2001 A Space Odyssey
New Technologies & the Search for -A Galaxy Insight
Lonely Hearts of the Cosmos Revisited -NASA's Phoenix Probe & the Search for
Eyes on the Cosmos -European Space Agency's Hawk 1 & Hubble's Successor

New Phoenix Mission Technology to Search for Life
Cruising the Goldilocks Zone -The Search for "Super-Earths"
Adventures of a Planet Hunter
Non-Carbon Lifeforms -Why We May Overlook
The Milky Way Enigma -How Galactic Forces May Control Life on Earth

Astro-Engineering Artifacts as Evidence of
The Biological Universe -A New Copernican Revolution?
 
Jupiter's Europa & the Search for
Earth's Twin Habitable?
Search for Extraterrestrial Genomes

Comments

There are a few considerations in regarding this issue that hardly anyone ever mentions in articles like these. A 'higher intelligence' other than our selves with an advanced civilization may be impossible to detect for any number of reasons that our level of intelligence cannot comprehend. It may be 'hidden' from us for any reason that it is simply impossible for us to consider at this stage. Something more intelligent than us, it's actions and existence may be impossible to detect because we cannot understand their reasoning. They may be hidden because they want to be hidden! And if so, there is nothing we can do about that other than evolve.

Any advanced civilzation would have to reach a very high system of ethics to continue on, and any such high system of ethics would need to include the value of life. Consider what would our civilization look like just 5k years from now if it is able to continue? Wars will not exist if we do.

Currently we use 10% of our brains capacity, when the human race is finally using at least, say, 80% our brains capacity, we will be able to find out for ourselves about E.T. How long will that take? I've never heard of any research with a goal to accomplish that end, have you? So, a long, long time, I should like to say!!!;)

Dennis I fully agree with you! If we cannot yet communicate with our own neighbors how can we communicate with other species outside of earth... Great comment!

There is a "ring pass not" around us.
Humanity is not ready for contact.
Look around, stupid people everywhere.

The point with Fermi's Paradox is that, if there has been technologically advanced civilizations in our galaxy, then there should be some indications of their existence.

A civilization a little more advanced than ours could build self-replicating Von Neumann probes. Over the course of 60-100 million years these probes would have visited all of the galaxy. We should be knee-deep in in proof of alien civilizations. Instead there is a great emptiness.

Civilizations this advanced would leave a heat signature that even we should be able to detect. Even they could not defy the Second Law of Thermodynamics; we'd see the infrared radiation their civilization would output.

@Chris
We have heard your nasty comment on everything including the comments that are described as 'ridiculous' without you let us know any answer or your comment to the main point....you pop up and disappear after a stupid and RIDICOULUS statement.

As a man I do NOT want to contact you ....IF I were an alien I had ignored the guys like you for millennia.

We have seen no IR stars with the unique signature of a Type II Dyson Swarm, the interception of most of a star's light by millions of orbiting habitats. This is something we'll be starting to do in another thousand years, after which we'll take over the Milky Way in only a million years, resulting in a Type III civilization, with Dyson Swarms around every last star in our Galaxy. That this hasn't happened is a strong indication that nobody in the Galaxy has yet reached space, in spite of its being nine billion years older than the Earth. But it gets worse.

No galaxies near our age (only those within a few billion light years) show any indication of Type III, which should be able to take over an entire cluster of galaxies in a mere billion years, so why don't we see them? Fermi's paradox is Universe-wide.

Only if space-faring intelligent life is cosmically rare to a degree extreme beyond our wildest pessemism could we see not even one galaxy 'going dark', as a triumphant Type-III-to-be settles huge swaths of its interstellar space. We should expect to never find any signals or ancient traces, so rare we are.

I love articles like this, they all contain the same information..how the distances are so fast no one could travel here given that yet fail to even acknowledge aliens understanding of physics MAY BE COMPLETELY DIFFERENT THAN OURS. We cant honestly think after a few hundred years we know it all, we dont even know what Dark Matter is which threatens to re-write all that we think we know. Further more a civilization so much older than ours will most like be able to beat the speed of light and time itself (wormholes at least) to get here. So I really hold little interest for the proclamations of a know it all author or scientist who says they could never get here.

Stop thinking like an arrogant human.

UFO/What are UFO's? they are flying space ships that defye gravity and are able to travel faster than the speed of light.
They are not from out of space, they from this planet itself, but from another dimension, they are able to go back in time or to the future. I think the reason that they are here is, because they are worry about us. The way we treat this planet. There so much destruction, so many wars,pollution, earth warming, or cooling.
They are making sure we don't destroy this planet and upset their future.

How can we know that extra-terrestrial life hasn't been discovered? How do we know they didn't discover us millenia ago? If either of these things ever occurred, what leads us to believe that we would be officially informed?

We must always ask questions.

they are invisible-they are living 200 light years away from the earth.they can change the phase and density.they are supernatural where we can not imagine.just leave thinking and focus on your mind and body. you will see the universe just 1mm away from you.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Your Information

(Name is required. Email address will not be displayed with the comment.)