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Billions of Habitable Planets...but where are the aliens?

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MyGodItsFullofStars Since: Feb, 2011
#1: Mar 28th 2012 at 8:24:08 PM

So a recent survey suggests that there could be close to at least 1 habitable planet per red dwarf in our galaxy - which if true means that there are billions of potentially habitable worlds within our galaxy.

So, where are all the aliens? Surely if there are billions of planets out there, it stands to reason that there are millions of intelligent species, and therefore at least a few thousand species that are more advanced than us. Which begs the question: why haven't we bumped into one of them yet?

My guess: Humans are the most advanced species in the galaxy technologically. Now hear me out, because that comes across as somewhat arrogant, but I think it makes some sense. Most of the stars out there that are older than our sun (and therefore would harbor older, more advanced civilizations) are too close to the center of the galaxy and thus are bathed in too much cosmic radiation for life to evolve. And most of the younger stars, the ones out by the rim, are too young for intelligent life to have evolved, or worse, lack heavy elements, which would prevent the rise of metalworking and likely be a big stumbling block for a technological society to develop.

The Sun, and thus Earth, are in that perfect "sweet spot": not too close to the center of the galaxy to get cooked, not too far out on the rim to lack the building blocks of technological society. We can also safely say that it is likely that there are no technological civilizations within a 50 light year radius of the sun, because we haven't picked up their radio chatter. Now you could argue that they don't use radio, but even if that were true you'd think that if an alien civilization was that advanced they would leave other signs of their presence - dyson spheres, or self-replicating interstellar probes, or something else we would have noticed. But all we have found so far is silence.

How do you explain this silence? Well, using occam's razor, the simplest explanation is that no one near us is using radio, because no one near us understands radio. Somehow humans won the lottery and evolved technological civilization ahead of the game (for all we know, every other nearby planet is still stuck in its awkward teenage "dinosaur" phase). Give us a few thousand more years, and we will be the advanced interstellar invaders coming to take over your neighborhood, muwhahahah!

Well, at least it would be kind of cool if in a few hundred years we do pick up a radio signal - an alien version of the first television broadcast, perhaps. I think it would be fun to watch another civilization take those first babysteps, you know?

MarkVonLewis Since: Jun, 2010
#2: Mar 28th 2012 at 8:26:16 PM

I think most of em in are New Jersey, actually.

MajorTom Since: Dec, 2009
#3: Mar 28th 2012 at 8:26:58 PM

Wasn't there an article that said basically we wouldn't ever hear alien messages by radio even if they came from Proxima Centauri? What with the Square-Cube Law applying to radio waves too meaning they degrade out to unreadable static in roughly just under 2 light years.

I think that's mentioned in the Aliens Steal Cable page.

Zyxzy Embrace the mindscrew from Salem, OR Since: Jan, 2001
Embrace the mindscrew
#4: Mar 28th 2012 at 8:27:03 PM

The entire point of Fermi's Paradox.

We have not been searching too long in the scheme of things, really.

What's the frequency Kenneth?|In case of war.
Accela Since: Feb, 2010 Relationship Status: I know
#5: Mar 28th 2012 at 8:28:02 PM

If there are aliens and they know about is, I hope they have the good sense to stay away until we get our planet sorted out.

Running into another intelligent form of life would be...chaotic for us. And I don't think we're really prepared for it yet.

TenTailsBeast The Ultimate Lifeform from The Culture Since: Feb, 2012
#6: Mar 28th 2012 at 8:41:09 PM

Well maybe abiogenesis is just really unlikely. Or it could be that complex multicellular life is really unlikely. Or it could be that species smart enough to create civilization are really unlikely. Or most scarily, perhaps almost all civilizations self-destruct. The most benign possibility would seem to be that advanced civilizations are common but focus on optimization instead of expansion (like in Accelerando).

I vowed, and so did you: Beyond this wall- we would make it through.
RTaco Since: Jul, 2009
#7: Mar 28th 2012 at 8:47:40 PM

If there really are billions of planets with life, the chances that Earth is the most technologically advanced is, well, one in billions. tongue

Astrosimi Astronomically Awesome from God's Waiting Room Since: Mar, 2010 Relationship Status: LA Woman, you're my woman
Astronomically Awesome
#8: Mar 28th 2012 at 8:57:46 PM

Yeah, it's most likely that the sort of tech that's required for efficient and plausible interstellar travel is so advanced even the oldest of theoretical civilizations have only recently or have yet to discover it. Or maybe it's not, but with billions of planets, why would they come here first? evil grin

edited 28th Mar '12 8:58:06 PM by Astrosimi

MajorTom Since: Dec, 2009
#9: Mar 28th 2012 at 9:00:00 PM

wild mass guess We've already been visited by aliens. Roswell was First Contact.wild mass guess

edited 28th Mar '12 9:01:31 PM by MajorTom

TenTailsBeast The Ultimate Lifeform from The Culture Since: Feb, 2012
#10: Mar 28th 2012 at 9:04:43 PM

Nah, galaxy colonization is pretty easy.

"It has been theorized that a self-replicating starship utilizing relatively conventional theoretical methods of interstellar travel (i.e., no exotic faster-than-light propulsion such as "warp drive", and speeds limited to an "average cruising speed" of 0.1c.) could spread throughout a galaxy the size of the Milky Way in as little as half a million years."

[1]

I vowed, and so did you: Beyond this wall- we would make it through.
RainbowMatt Prettiest Pony :3 from the cave of unspeakable naughtiness Since: Oct, 2011 Relationship Status: And they all lived happily ever after <3
Prettiest Pony :3
#11: Mar 28th 2012 at 9:04:56 PM

You have to keep in mind Earths location in reference to the galaxy as a whole. We are towards the end of one of the spiral arms. We are basically in the boonies. It does not surprise me we have not been contacted.

Devypu's~ Big Pony :3
Grimview Catalytic from British Columbia Since: Mar, 2012
Catalytic
#12: Mar 28th 2012 at 9:15:01 PM

Simplest possible explanation:

The laws of physics (and, in particular, General Relativity) assume and predict that, no matter where you are in the universe, the physics of the universe are the same.

If it took 14 or so billion years for life on Earth to develop to humanity's current technological level, what possible physical reason could there be for conditions anywhere else in the universe to allow life to reach a similar technological level at any faster rate?

At best, other species are around our level, plus or minus a couple thousand years of development.

A few thousand years, maybe, but that is nowhere near long enough for significant spreading into an interstellar empire in a universe with a speed limit and relativistic speed considerations limiting space travel. (Which we live in)

In other words, we haven't seen aliens because based on all known laws of physics, life as we know it could not possibly have evolved and advanced in civilisation and technology to our present level - much less beyond it - any more than perhaps a few thousand years before us. Many other lifeforms may in fact be a few thousand years behind us.

We haven't met them yet because we aren't able to go and find them ourselves, so based on the age of the universe and laws of physics, there is no logical reason aside extreme proximity (such as another sentient race existing in the Alpha Centauri system, for example) that we would encounter another intelligent race in the universe until we are equally capable (or approaching equal capability) to find them as they are to find us.

"Lock up your girlfriends, lock up your wives, Grim's on the loose so run for your lives." - Pyrite
Jimmmyman10 cannot into space from polan Since: Mar, 2011 Relationship Status: Armed with the Power of Love
AikoHeiwa I AM NOT A TREE from Aikoland Since: Feb, 2011
I AM NOT A TREE
#14: Mar 28th 2012 at 9:20:15 PM

wild mass guessThere are no aliens. Humanity isn't even real. We're just a game of The Sims 42wild mass guess

NO TREE FOR ME (ALSO LOVES HER BOYFRIEND)
Zyxzy Embrace the mindscrew from Salem, OR Since: Jan, 2001
Embrace the mindscrew
#15: Mar 28th 2012 at 9:23:03 PM

Though, that assumes other species or biospheres must develop along similar lines. We only have one example.

What's the frequency Kenneth?|In case of war.
TenTailsBeast The Ultimate Lifeform from The Culture Since: Feb, 2012
#16: Mar 28th 2012 at 9:24:31 PM

And all other solar systems formed within a few hundred thousand years of our own? Seriously?

edited 28th Mar '12 9:24:58 PM by TenTailsBeast

I vowed, and so did you: Beyond this wall- we would make it through.
Grimview Catalytic from British Columbia Since: Mar, 2012
Catalytic
#17: Mar 28th 2012 at 9:35:44 PM

... The evolution of the universe is pretty well plotted out, guys.

The highest mass stars came first.

As they were high mass, they burned out, blew up, and became supernovae.

Said supernovae condensed into new stars, locally, creating the many billions of stars we now see.

Planets then began to form from leftover matter around those stars.

The Earth is about 4.5 billion years old.

The universe is about 14 billion years old. I can't remember if it's "a little above" or "a little under" that figure, but it's roughly 14 billion years old.

As a consequence of this, if we are looking for other lifeforms we would recognise as lifeforms - ie, those that evolved in the "Goldilocks Zone" of their star, on a planet within a few orders of magnitude of Earth mass, with a stable atmosphere, and liquid water - we have a pretty exact timeline to follow. Plus or minus a million years on a geologic timescale has some significance, yes, but given the actual planetary masses and chemical compositions, an extra hundred million years may be necessary to create conditions similar to Earth's.

And why are we limiting searches to places similar to Earth?

Simple: Current theories and predictions suggest there are as many as a hundred billion (and at least a billion) Earth-like planets in the Milky Way. As we know life can form on these planets, they are the best candidates for investigation.

Before anyone suggests we look for non-carbon based life, I'll paraphrase Neil deGrasse Tyson:

We, as humans, are largely made up of Water. Water is made up of Hydrogen and Oxygen - the FIRST and EIGHTH most abundant elements in the universe. Much of the rest of our bodies is composed of Carbon - the SIXTH most abundant element in the universe.

Chemically speaking, humanity is nothing special.

Cosmically speaking, Earth is nothing special, nor is our sun, Sol.

The most likely formula for life is simple elements (first few rows of the periodic table), in the Goldilocks Zone (roughly 1 Astronomical Unit from the planet's sun), on a planet with abundant water and stable climates.

As the age of the universe is known, and the stellar life cycle is reasonably well understood, as well as planetary formation... we can predict a great number of the things associated with the likelihood of intelligent life elsewhere. All of it points to no one being too far ahead of or behind ourselves.

"Lock up your girlfriends, lock up your wives, Grim's on the loose so run for your lives." - Pyrite
Zyxzy Embrace the mindscrew from Salem, OR Since: Jan, 2001
Embrace the mindscrew
#18: Mar 28th 2012 at 9:39:33 PM

But it is entirely possible for their to be lifeforms from non-similar processes.

You ever read Evolving the Alien?

What's the frequency Kenneth?|In case of war.
ElRigo I'm freezing! Send help! from Baja Since: Nov, 2010 Relationship Status: Awaiting my mail-order bride
I'm freezing! Send help!
#19: Mar 28th 2012 at 9:40:59 PM

Maybe we are the aliens?

TenTailsBeast The Ultimate Lifeform from The Culture Since: Feb, 2012
#20: Mar 28th 2012 at 9:41:36 PM

Yes, yes. Could state the reason why other civilization have to be in extremely exact lockstep with our own? Without saying "from what we know", actually state the reason. And as I pointed out earlier, as little as a half a million years can make a massive difference.

edited 28th Mar '12 9:44:48 PM by TenTailsBeast

I vowed, and so did you: Beyond this wall- we would make it through.
Grimview Catalytic from British Columbia Since: Mar, 2012
Catalytic
#21: Mar 28th 2012 at 9:45:21 PM

It is possible, but it is much less likely.

Our chemistry is based on some of the simplest elements in the universe, and the most abundant.

We are beginning to find more and more planets in the same zones around their suns that we are around ours.

More and more of them with liquid water, and similar masses to the Earth.

I'm not claiming we'll meet humanoid lifeforms. But I am saying that, based on simple logic, anything else we meet in the universe is looking increasingly likely to be of similar chemical and physical bases, and to have evolved on planets with similar conditions.

Mars is barren, though there are hints that life may have started and failed there, though nowhere near confirmed. Gas giants are uninhabitable. Mercury would boil anything to touch its surface (or freeze it, on the night side). Venus' atmosphere would tear anything organic apart. Pluto is too cold, as are the other exoplanets.

The conditions of the universe all point toward Earth-like planets being the best candidates for life to evolve.

"Lock up your girlfriends, lock up your wives, Grim's on the loose so run for your lives." - Pyrite
djmaca Secret Character from Philippines Since: Apr, 2010
Secret Character
#22: Mar 28th 2012 at 9:48:39 PM

[up]My guess is that there are aliens. And they have the tech for space travel. But like us, progress isn't going as good as people, and alien fans, want it.

...a little brother should belong to his older sister, right? - Orimura Chifuyu
Grimview Catalytic from British Columbia Since: Mar, 2012
Catalytic
#23: Mar 28th 2012 at 9:51:25 PM

@Ten Tails:

Physics is the same everywhere in the universe.

If you have a planet that is, say, half Earth's mass, in order to develop Earth-like conditions, you may get lucky and have it take a few million years less; you may get unlucky and have it take a hundred million years more. (or vice versa) The accretion period of the planet's crust will be shorter, almost definitely, but that does not mean surface conditions will be suitable for evolution any earlier than they were on Earth.

But if you have less mass, you have less resources, due to lower elemental composition in the planet. You have less likelihood of high-mass elements like uranium and heavy metals, which are currently vital to various scientific research into getting us further into space.

If you have higher mass, you have a longer accretion period for the planet to solidify to having a crust - period. That is unavoidable. Conditions from there may advance faster or slower, but bear in mind that for the first two or so billion years of Earth's existence the crust was still mostly molten rock. If you have a higher mass planet, you will have more high-mass elements and more resources, yes. But you also delay the onset of organic life's ability to begin evolving, due to the longer accretion period.

Stellar and planetary evolution are the primary factors pointing to the simple fact that it is entirely logical lifeforms in the universe are all within, at most a hundred or two hundred thousand years of each other. This is excluding the likelihoods of extinction events, like the one that destroyed the dinosaurs, being able to wipe out "civilised" societies.

"Lock up your girlfriends, lock up your wives, Grim's on the loose so run for your lives." - Pyrite
HungryJoe Gristknife from Under the Tree Since: Dec, 2009
Gristknife
#24: Mar 28th 2012 at 9:51:26 PM

Seeing some Antrhopic Principle in here.

There are stars billions of years older than our sun. They could've had life supporting planets well before we did that evolved more advanced civilizations.

My personal and completely un-backed theory is that most intelligent life, since the majority of all life, evolves in the seas. An aquatic species wouldn't be likely to use tons of EM Radiation,since it has such limited use in their natural environment.

Charlie Tunoku is a lover and a fighter.
djmaca Secret Character from Philippines Since: Apr, 2010
Secret Character
#25: Mar 28th 2012 at 9:54:09 PM

Hyperdolphins?

...a little brother should belong to his older sister, right? - Orimura Chifuyu

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