The "Multi or Rare" Earth Debate: Are We the Sole Intelligent Life in the Milky Way?

The "Rare Earth" hypothesis is the idea that life is a staggeringly unlikely event, and that the reason we haven't seen hide nor hair (nor scale nor weird gel-layer) of aliens is that there aren't any.  It's had some time in the spotlight, it makes us sound very important, and it's wrong.

The Rare Earth argument ignores a number of essential factors, the first being how staggeringly huge the numbers involved are.  Even the Milky Way has 200 to 400 billion stars, and it's only one of a hundred billion galaxies in the observable universe, and there have been billions of years for things to happen.  Countering "it's really unlikely" with "but there are lots of things!" might sound weak, but it's the Rare Earthers who are taking the burden of proof - claiming that nothing happens anywhere else ever.  The more places there are, the worse their argument gets.

Geologist Peter Ward and astrobiologist Donald Brownlee, both of the University of Washington have outlined a short list of conditions needed: Right distance from a star; habitat for complex life; liquid water near surface; far enough to avoid tidal lock; right mass of star with long enough lifetime and not too much ultraviolet; stable planetary orbits; right planet mass to maintain atmosphere and ocean with a solid molten core and enough heat for plate tectonics; a Jupiter-like neighbor to clear out comets and asteroids; plate tectonics to build up land mass, enhance bio-diversity, and enable a magnetic field; not too much, nor too little ocean; a large moon at the right distance to stabilize tilt; a small Mars-like neighbor as possible source to seed Earth-like planet; maintenance of adequate temperature, composition and pressure for plants and animals; a galaxy with enough heavy elements, not too small, ellipitcal or irregular; right position the galaxy; few giant impacts like had 65 million years ago; enough carbon for life, but not enough for runaway greenhouse effect; evolution of oxygen and photosynthesis; and, of course, biological evolution.

Claims that there aren't many suitable planets over all these stars are like hiding in a closet and claiming there's no such thing as coffee tables - we're now detecting planets at an ever-increasing rate, because now we have technology actually capable of detecting planets.  Almost as soon as we try any new planet-detecting technique it detects a whole bunch of the things.  We're even edging into the ability to find Earth-size planets, and what do you know?  There they are!  And some even have water!

The second slip-up is ignoring the suitability of the laws of physics to life - or rather, the suitability of our form of life to the laws of physics. The idea of someone sitting in pre-existence limbo and tuning the weak nuclear force in order to create bald monkeys is patently ridiculous, as is the idea that only a tiny range of values could give rise to any repeating pattern - our pattern, DNA, is just the one that happened to work for the collection of constants we call reality.

Once life is possible in a universe, expecting it to occur in one place only is like leaving a loaf of bread and expecting exactly one slice to go moldy.  Life just happens here - thermodynamic math has shown that amino acids simply will be built anywhere their components can be found.  Since those components are on the periodic table, the literal "this is what happens in this universe" list, they're going to be all over.  Assuming aliens don't come up with another pattern anyway (increasing the odds again).

Claiming that we're the only life in existence is a combination of ignorance and self-importance that should have a livejournal, not a scientific journal.  The important work is getting ourselves out there and seeing who and/or what we can find.

The "Rare Earth" Delusion

Posted by Luke McKinney.

Related Galaxy posts:

MIT Asks: How Would Extraterrestrial Astronomers Study Earth?
"The Great Silence" -A Galaxy Insight
Harvard-Smithsonian Scientists Zero In On Key Sign of Habitable Worlds
Cruising the Goldilocks Zone -The Search for Super Earths
Dead Zones in the Search for Extraterrestrial Life
GAIA -Mapping the Family Tree of the Milky Way
The "Hubble Effect" -A Galaxy Insight
James Cameron & Arthur C Clarke on 2001 A Space Odyssey
Eyes on the Cosmos -European Space Agency's Hawk 1 & Hubble's Successor
New Phoenix Mission Technology to Search for Life
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 Extraterrestrial  Life
The Biological Universe -A New Copernican Revolution 
Jupiter's Europa & the Search for Extraterrestrial Life
Earth's Twin Habitable?

Comments

[Jon]

Another terrible article by Luke. You always present a one sided argument and always throw insults at any views opposing yours.

"Claiming that we're the only life in existence is a combination of ignorance, self-importance and depression that should have a livejournal, not a scientific journal. "

Is that really necessary? Especially because you missed the main point of the Rare Earth argument which is even though there are vast numbers it's possible that life or intelligent life exists for such a short time span that it is very unlikely for 2 intelligent entities to coexist at the same time and or near each other.

I really like this web site but, every single article you post is full of insults, terrible attempts at sarcastic analogies, and misinformed information.

Please stop writing for the DG, you are ruining it.

[MARK PORTER]

I would love to think that there are many planets with intelligent life out there. Maybe there are, "BUT" when you consider in order to have an earthlike planet all these events need to happen.
1. In goldilocks zone
2. planet of similar size
3. moon (what are the odds of having a mars sized body, strike the earth at the exactly perfect angle to cause the impact to throw enough material out into space and that material coalesced into our moon.
4. protective giant planets (that absorbed many earth killer rocks over the billions of yrs necessary for evolution.
5. a Sun/star just the right size & age for this solar system.
6. the cooling of earth and the formation of it molten core to allow for evolution.
If you add up all the odds for each of the above events to happen at just the right time over a 5+/- billion yrs period. What are the total odds of it realistically happen again.
Just off the top of my head 3.5 trillion to 1!!!! :)
But, I really do hope I'm wrong!!
Mark

[woody]

If you consider how short life one earth has been and will be, let alone the ridiculously short span of human life, how likely is it that life on other planets will coincide with ours so that we can eventually detect each other?

[Travis O. D.]

unfortunately I dont mean to ruin your strong beliefs...

but its time to lay down facts whether or not you accept them, whether or not you can come to terms with them, and whether or not your even smart/aware enough to comprehend this revelation.

The are over 55+ species of advanced beings similar to humans,
and in our solar system especially WE ARE "NOT" the most advanced...

to smack u in the face with a fresh breath of reality other races and beings exist on other multiple dimension which are LAYERED precisely over eachother......

the most advanced beings of OUR solar system, are the HATHORS... which are depicted and sculptured in EGYPT...
they stand to 14 to 16ft tall and function through the 4th dimension... on Venus.

there are sooo many races and species to be learning about or shall i say "REMEMBERING" sounds more precise.

Nefilim, Sirians, Greys... it goes on and on...

HUMANS YOU HAVE NOOOOO CLUE, PLEASE WAKE UP FROM YOUR SLEEP...

WE"VE BEEN HERE FOR 200,000 YEARS AND HAVE ABSOLUTELY NOOOOOO CLUE AS A MAJORITY....

those that do such as I will keep pushin and pushing until the day comes there is no need for me to do such a strenuous straining action.

until then, I shall persist... and awaken all from withing there haerts and beyond...

[Nevermind]

I thought the Galaxy attracted readers with at least a partially-working brain. Looks like this is clearly not true. I actually love your humorous/ironic/sarcastic comments about hypothesis that don't hold themselves together, in fact, it's one of the reasons I love the DG articles.

But I didn't come here to comment that. I just wanted to say that the title is wrong on this one. It's truly another "A Galaxy Classic".

[Casey Kazan]

Okay...we're taking Luke off red meat and putting him on a strict soy and veggie diet! Pls know that Luke is a both a brilliant if provocative physicist with one of the world's great universities.

Casey Kazan -Editor, The Daily Galaxy

[Ivar Nielsen]

Are we at all intelligent in the NATURAL meaning of this word?

Natural Philosopher Ivar Nielsen - www.native-science.net

[Mark]

No signals. No habitable Earthlike planets anywhere nearby. No visitation in history or pre-history.

Despite the nearly infinite vastness of space. Despite the near infinite number of planets that must exist in our galaxy alone. There is no evidence that we are NOT alone.

As far as we KNOW right this second, we are utterly alone. And it is irrelevant if we aren't. Because they'll never reach our planet. And we'll never reach their planet.

So, it's incumbent upon us to somehow manage our species long enough to prevent total planetary meltdown so that we can enjoy our long slide into the future.

[Jonathan Ainsley Bain]

Consider that life took 4 billion years to reach space exploration. The next 1 billion years are going to take us to the stars.

1 billion years from now, we are likely to be able to move a planet into the goldilocks zone. Place a moon in the correct orbit. Engineer the correct elements on the surface. Introduce life. Foster it.

1 billion years from now, we will have colonised millions of stars.
Now as the first of these beings start exploring space, they are all going to say 'but its so unlikely, surely WE are the first and only beings.'

The odds of that life-form being correct in that statement are worse than 1 billion to 1.

[Basuto9]

WOW! Now this is why I read The Daily Galaxy, to learn new things. I didn't even KNOW about the HATHORS, or living in the fourth dimension on Venus. I am aware of the Sirians, of course (who isn't, duh!) but the Nefilim, who knew? Thanks, Travis (for the fun comment - it was in fun, wasn't it?).

[Greg F.]

The Rare Earth Hypothesis simply says that planets as hospitable to complex life as our own are scattered all over the universe but at great distance from each other and whatever intelligent life may evolve on them is probably not going to be in the same time frame.

To go on a rant disparaging a measured guess by the very people who look for other planets and alien life with barely any point to it while ignoring the complex science behind it is downright lazy.

I highly suggest that the author actually study the science involved before making grand proclamations.

[Rajnish Roy]

There is no doubt Luke McKinney has done a great job. It not just unfair but unwise to castigte him. Similarly Casey Kazan has been doing admirable service. My thanks to them.

Rajnish Roy
http://rewiringthebrain.net/

[Rajnish Roy]

There is no doubt Luke McKinney has done a great job. It is not just unfair but unwise to castigte him. Similarly Casey Kazan has been doing admirable service. My thanks to them.
Rajnish Roy
http://rewiringthebrain.net/

[pikestaffpikestaffestaff]

I am sure that Eziekial [some chap in the Bible] wrote about a visit he had from alians, when they left, they ascended to heaven on 'pillars of fire'???
I also believe a seventeenth century French monk also wrote about a visit he had from 'alians"???

[claudio]

I tend to disagree with the comments posted by Jon .
The article might look like 'somewhat biased' by the Luke's personal opinion about this 'difficult and interesting subject'....however the simple fact that the question is posed ....AGAIN and AGAIN ....in this review-magazine....is an indicator that the subject and the associated question : 'are we alone ?? ' is far from being considered stupid or resolved.

NO WE ARE NOT ALONE...even in this periphery galaxy of the 'Local Group' ..in turn part of the 'Virgo Cluster' ...which is part of the so called 'Supercluster of galaxies'.

However the space-time web may have an influence on us being able to talk with 'others of similar nature' (i.e. intelligent kinds).....

Also the very naive ways of detecing comms around us (PLS refer to SETI program) does NOT help much...however that is what we are presently able....in technology terms.

Regards to the other friendly & intelligent species....of this galaxy.

[BoT]

Until life elsewhere is discovered, we have nothing to use to assign it a probability of occurrence except assumptions. One can *say* that given a certain set of circumstances--presence of water, natural tendency for amino acids to form, etc etc--life is ineluctably produced. You assume we are now aware of all the necessary ingredients to make life happen. And you may be right. But you may be wrong; that is the nature, after all, of *assumptions*.

Unfortunately, *as far as we know* life has only happened once.

The galaxy may be lousy with life. In that case, your 'loaf' analogy could have merit. On the other hand, here's another analogy: the rise of life might be as likely as billiard balls returning to their original racked position after a break. We just don't know yet, given the evidence.

So enjoy yourself, believe what you want, but don't *kid* yourself into thinking you know what the probabilities are here.

[por-stair]

Again Carl Sagan would post-humously say YES. If they are beings as intelligent as we are- I'm not sure if we would be fit subject matter.

[j becker]

This is it get over it. There is no one else out there. I'm sorry that your fragile egos can't take it.

[bitirim]

thank you

sohbet siteleri sohbet sitesi sohbet odaları sohbet kanalları sohbet seviyeli sohbet