The Fermi Paradox ...life in the galaxy explained

[Jeff V]

Yeah, unless some civilization put out a high-powered beacon expressly for the purpose of being detected, it is doubtful we could distinguish signs from natural phenomena. But that would be incredibly stupid and reckless.

That's why we need to place a beacon in the Alpha Centauri system then watch and see what happens.

[noxiousdog]

The best example might be brown dwarfs. At only 250-600 degrees C, we can still see them.

I'm sorry, but that's a horrible example. A civilization doesn't output anywhere close to that amount of energy on a planet-scale basis. The extremely limited spots in which we do are so small as to be undetectable at these distances, and even if we could detect them we'd probably be unable to distinguish them from natural radioactive, volcanic or chemical activity.

I don't think you realize how little energy that is.

And you absolutely can tell the difference based on the wavelengths of of the energy. We're not talking about any civilzation. We're talking about one with the capacity for interstellar travel.

[TiLT]

The best example might be brown dwarfs. At only 250-600 degrees C, we can still see them.

I'm sorry, but that's a horrible example. A civilization doesn't output anywhere close to that amount of energy on a planet-scale basis. The extremely limited spots in which we do are so small as to be undetectable at these distances, and even if we could detect them we'd probably be unable to distinguish them from natural radioactive, volcanic or chemical activity.

I don't think you realize how little energy that is.

And you absolutely can tell the difference based on the wavelengths of of the energy. We're not talking about any civilzation. We're talking about one with the capacity for interstellar travel.

I realize that it's 250-600 degrees C. Humanity doesn't even output a fraction of that in all but extremely isolated machinery, and you're describing an entire planet with such energy output. What kind of energy are you talking about? It clearly can't be heat, so what is it? Radioactivity? Light? Radio waves? Something else?

Also, a civilization that advanced would theoretically also be advanced enough not to "leak" energy to the point where it would be that observable, even if they've colonized every little centimeter of their planet(s).

[Jaymann]

Yeah, unless some civilization put out a high-powered beacon expressly for the purpose of being detected, it is doubtful we could distinguish signs from natural phenomena. But that would be incredibly stupid and reckless.

That's why we need to place a beacon in the Alpha Centauri system then watch and see what happens.

Maybe all the intelligent civilizations have read Hawking and Sagan, and they are hiding from each other.

[GreenGoo]

Yeah, unless some civilization put out a high-powered beacon expressly for the purpose of being detected, it is doubtful we could distinguish signs from natural phenomena. But that would be incredibly stupid and reckless.

That's why we need to place a beacon in the Alpha Centauri system then watch and see what happens.

Imma hidin' in da bushes.

[noxiousdog]

I realize that it's 250-600 degrees C. Humanity doesn't even output a fraction of that in all but extremely isolated machinery, and you're describing an entire planet with such energy output.

Yes it does. Pretty consistently. Heat is very low energy. That's far less than is required to melt steel.

What kind of energy are you talking about? It clearly can't be heat, so what is it? Radioactivity? Light? Radio waves? Something else?

Energy. All of it. Heat, electricity, radio waves, etc. It's all energy it all has to go somewhere.

Also, a civilization that advanced would theoretically also be advanced enough not to "leak" energy to the point where it would be that observable, even if they've colonized every little centimeter of their planet(s).

Why? And how could they not radiate heat?

[Kraken]

How a species could become immortal I have no idea. Science? Evolution? Magic? I think a species that came into existence immortal would probably not have the same biological drives that shorter lived species. A species that becomes immortal might lose those drives.

There would be no evolution without death. Complex life won't arise without it. That's not to say that death can never be overcome, but if immortality appears spontaneously then that species stops changing, so it's counterproductive to complex life.

I don't disagree, but I think it's simply our imaginations failing us at this point, since our reality is so completely dominated by the concept of iterative evolution.

That said, what happens if evolution produces immortality? Or science (which some people would argue is just a part of evolution)? Do we keep pumping out kids? If the change is abrupt, maybe we do. If it's gradual, maybe we lose that drive.

The mating instinct is strong and children are the default consequence, so I can't see that changing very quickly. I wonder, though, if immortals would remain fertile for more than the customary few decades. I suppose it would depend on what happens to the trajectory of aging.

[Jeff V]

How a species could become immortal I have no idea. Science? Evolution? Magic? I think a species that came into existence immortal would probably not have the same biological drives that shorter lived species. A species that becomes immortal might lose those drives.

There would be no evolution without death. Complex life won't arise without it. That's not to say that death can never be overcome, but if immortality appears spontaneously then that species stops changing, so it's counterproductive to complex life.

I don't disagree, but I think it's simply our imaginations failing us at this point, since our reality is so completely dominated by the concept of iterative evolution.

That said, what happens if evolution produces immortality? Or science (which some people would argue is just a part of evolution)? Do we keep pumping out kids? If the change is abrupt, maybe we do. If it's gradual, maybe we lose that drive.

The mating instinct is strong and children are the default consequence, so I can't see that changing very quickly. I wonder, though, if immortals would remain fertile for more than the customary few decades. I suppose it would depend on what happens to the trajectory of aging.

Everyone knows that at about 200 years, your penis will just fall off.

Aging is a complex thing. Much of what kills us is the breakdown of cells from a lifetime of exposure to various toxins. But say we find a way to effectively cleanse the body and remove this particular hazard, greatly extending our lives. Would that effect the timing of hormonal changes that trigger things like menopause? If not, the female half of the race might remain a bunch of hot milfs...hot, sterile milfs. I would think that sort of immortality would just be a pitstop on the way to extinction.

[TiLT]

I realize that it's 250-600 degrees C. Humanity doesn't even output a fraction of that in all but extremely isolated machinery, and you're describing an entire planet with such energy output.

Yes it does. Pretty consistently. Heat is very low energy. That's far less than is required to melt steel.

What heat would this be? You keep talking about it, but you also keep failing to explain what you're talking about.

[msduncan]

The more I think about it, the more I'm leaning towards the great filter being behind us. It would explain the difficulty we are having in intercepting any signs of activity from alien races. Essentially there would be other civilizations out there (a bunch more) but due to the size of the Universe and the drastically reduced numbers of them (because of the great filter) they would be far flung and hearing them would be like looking for a needle in a haystack.

If the great filter were ahead of us and many many civilizations reach our level before hitting that brick wall -- we would hear them. Many of them would have developed to our level and hit the filter and blinked out a LONG time before us and thus their chatter would presumably have had time to drift through the cosmos to us.

[Nightwish]

One thing I don't understand is the idea that a civilization so advanced in science, which requires concerted civilized effort, that it can conquer the vast distances of space as well as the ability to generate unimaginable amounts of energy would bother to conquer or kill another sentient species. Space is huge!
It's great for sci-fi stories, but, if you think about it, colonies in Star Trek and similar series must be really, really, really small, there's just not enough people and interest in procreation to fill them.

As for FTL, apparently NASA is testing star-trek-like warp drive viability based on a new phenomenon so far attributed to negative energy which does not violate relativity, so who knows? It would be terribly depressing if there is no way to do it, at least.

The worst part of it all is that we will never know in our lifetimes.

[Daehawk]

Wouldn't the galaxies and stars ahead of us be older and therefore have more chance of having an aleins race....a more advanced one....or even dead ones? Those galaxies and stars behind us would be younger the further bac kwe go so they would have fewer or new civilizations unless there is some radically speedy one out there.

I remember on Voyager once they got stuck at a planet that on it time was moving really fast compared to the rest of the universe. So in a matter of days they advanced from tribal to space faring with tech better than Voyager had. In fact they saved Voyager hehehe.

[Kraken]

I don't know what you mean by "ahead of" and "behind." The oldest stars had low percentages of heavy elements. Their planets would be resource-poor and might lack the complexity necessary for life (if that's what you meant). Although astronomers have recently found ancient stars with richer-than-expected compositions that current theory can't explain, so you can't say that the universe was lifeless until it reached some critical age.

[noxiousdog]

I realize that it's 250-600 degrees C. Humanity doesn't even output a fraction of that in all but extremely isolated machinery, and you're describing an entire planet with such energy output.

Yes it does. Pretty consistently. Heat is very low energy. That's far less than is required to melt steel.

What heat would this be? You keep talking about it, but you also keep failing to explain what you're talking about.

Where do you think the heat generated by industry (electricity, cars, factories, etc) goes?

[Daehawk]

The universe is expanding. Those galaxies at the furthest edge of the universe ae older.....the ones going away from us. those coming towards us and 'behind' us are younger. Looking to the edge is like looking back in time.

[Jaymann]

The universe is expanding. Those galaxies at the furthest edge of the universe ae older.....the ones going away from us. those coming towards us and 'behind' us are younger. Looking to the edge is like looking back in time.

There are no galaxies coming towards us. All galaxies are expanding away from all other galaxies. To visualize this, think of spots on a balloon that is being blown up.

[gameoverman]

If it took two billion years for life to pop up on Earth, and we know the universe is about 13ish billion years old, that implies that stuff from 11 billion years old and younger would be where to start looking.

Also, I was just thinking, maybe the Great Filter is related to the lifetime of the planet's Sun. Using Earth as an example, maybe intelligent life on Earth(humans) has X amount of time to figure out how to leave the nest. If we are still stuck here when the Sun shines for the last time= Great Filter.

Various types of stars have different life spans, so some aliens might luck out and be able to survive, but others get the short end of the stick and are snuffed out even though they might have otherwise been the most advanced intelligences of all.

The ones who make it out might only advance far enough to hop from neighboring star to neighboring star, let's say 25 light years or less. So no one would colonize the entire galaxy due to lack of fast travel ability AND due to the need to keep moving. Imagine you have an RV and you spend your life traveling from camping spot to camping spot. Eventually you might have hit all 50 states but you are only ever in one location at any given time and no one would ever find any sign of you except in the location you are currently in.

[Daehawk]

The universe is expanding. Those galaxies at the furthest edge of the universe ae older.....the ones going away from us. those coming towards us and 'behind' us are younger. Looking to the edge is like looking back in time.

There are no galaxies coming towards us. All galaxies are expanding away from all other galaxies. To visualize this, think of spots on a balloon that is being blown up.

From all Ive read there are actually. They use the light waves to tell the difference...blue shift and red shift. I think its red away and blue towards.

[Turtle]

One thing I have to say is that the Fermi Paradox is a thought experiment made by someone in what, the 1950s?

It's not a mathematical equation, or based on some kind of physical constant.

And the ideas behind it are tainted by all sorts of wrong information and assumptions. The thought that why haven't we encountered alien life that could be millions of light years away is made trivial by our knowledge now of just how far it is, and that there may never be a way to travel faster than light.

That said, like this article, the most interesting thing about this is the thought processes behind it, but I still don't think it's a special idea at all.

[GreenGoo]

The universe is expanding. Those galaxies at the furthest edge of the universe ae older.....the ones going away from us. those coming towards us and 'behind' us are younger. Looking to the edge is like looking back in time.

There are no galaxies coming towards us. All galaxies are expanding away from all other galaxies. To visualize this, think of spots on a balloon that is being blown up.

From all Ive read there are actually. They use the light waves to tell the difference...blue shift and red shift. I think its red away and blue towards.

Yeah, I recently read that we can expect a galactic collision with the milky way in a few billion years.

Here it is:

The Andromeda–Milky Way collision is a galactic collision predicted to occur in about 4 billion years between the two largest galaxies in the Local Group—the Milky Way (which contains our Solar System and Earth) and the Andromeda Galaxy[1][2][3] although the stars involved are sufficiently far apart that it is improbable that any of them will individually collide.[4]

[GreenGoo]

One thing I have to say is that the Fermi Paradox is a thought experiment made by someone in what, the 1950s?

It's not a mathematical equation, or based on some kind of physical constant.

And the ideas behind it are tainted by all sorts of wrong information and assumptions. The thought that why haven't we encountered alien life that could be millions of light years away is made trivial by our knowledge now of just how far it is, and that there may never be a way to travel faster than light.

That said, like this article, the most interesting thing about this is the thought processes behind it, but I still don't think it's a special idea at all.

Not really. It's a very simple thought experiment based on probability, exponential growth, time and distance as well as (a fraction of) the speed of light, a physical constant. While our understanding of the universe is significantly greater than it was, nothing that we have learned impacts this experiment significantly enough to prove the premise wrong on its face.

The 50's weren't the dark ages. General Relativity was put forth as a theory in the early 1900's, with acceptance being around 1915. Special relativity showed up in 1907. The 50's were nearly half a century after that.

[edit: substitute 50's for 60's]

[The Meal]

The universe is expanding. Those galaxies at the furthest edge of the universe ae older.....the ones going away from us. those coming towards us and 'behind' us are younger. Looking to the edge is like looking back in time.

There's no edge to the expanding universe. Just the edge of what we're capable of seeing based on how light travels. No one point in the universe is farther from the center of the universe than any other.

The universe is expanding. Those galaxies at the furthest edge of the universe ae older.....the ones going away from us. those coming towards us and 'behind' us are younger. Looking to the edge is like looking back in time.

There are no galaxies coming towards us. All galaxies are expanding away from all other galaxies. To visualize this, think of spots on a balloon that is being blown up.

The Andromeda galaxy (which is right next door to the Milky Way) is approaching at a speed of about 68 miles per second and arrives in just under 4 billion years. AFAIK, that's the only approaching galaxy of note. We're neighborly enough that gravity is bringing them together at a faster rate than the cosmic expansion is pushing (pulling?) things apart.

There's a ton of bad information and really terrible guesses in this thread, but honestly I don't have the energy to go through things to make corrections (and only wanted to cherry pick a few here at the end). Cosmology is fun to think about in terms of thought experiments but there's a lot of stuff we know a whole lot better than some of you imagine. No offense intended, but I don't want to think that just because I corrected these last few items that means I'm giving a free pass to everything leading up to this point.

[GreenGoo]

There's a ton of bad information and really terrible guesses in this thread, but honestly I don't have the energy to go through things to make corrections (and only wanted to cherry pick a few here at the end). Cosmology is fun to think about in terms of thought experiments but there's a lot of stuff we know a whole lot better than some of you imagine. No offense intended, but I don't want to think that just because I corrected these last few items that means I'm giving a free pass to everything leading up to this point.

Maybe you can return after some rest?

I think in this thread particularly (versus a thread about how great Scarlet J is) it would be beneficial to correct any errors and try to keep opinion separate from currently understood facts. I'd gladly take a beat down if I said something inaccurate in a thread like this, although I don't think I went out on a limb much, this time.

[Turtle]

There's a lot of things we know now as fact that were not theories, but rather just hypothesized back in the 50s. That's important to note, I know full well that people and science knew a lot of things earlier than what most people believe. But Fermi's Paradox is just a fun excursion, not really worth the time that people put into it. It is, for all intents and purposes, played out, and a lot of what we know now invalidates core assumptions of Fermi's Paradox.

Even Fermi himself didn't take this idea too seriously. Much like how the idea of Schodinger's cat was never Schrodinger's idea of how the quantum world worked, but was Schrodinger trying to demonstrate how silly the idea was to think of quantum effects in the overly simplistic way people were, hence the use of a cat.

Also, the speed of light is a constant, but not in the way most people think.

[Kraken]

The universe is expanding. Those galaxies at the furthest edge of the universe ae older.....the ones going away from us. those coming towards us and 'behind' us are younger. Looking to the edge is like looking back in time.

There are no galaxies coming towards us. All galaxies are expanding away from all other galaxies. To visualize this, think of spots on a balloon that is being blown up.

Actually, galaxies merge all the time. Andromeda is moving toward the Milky Way and will collide in a few billion years. The Milky Way's satellite "clouds" are remnants of galaxies that it gobbled up. All of the local galaxies are moving toward a Great Attractor. Here's a map of our supercluster showing the motions of its component galaxies:



That doesn't mean that galaxies moving toward us are younger, though.

[Jaymann]

The universe is expanding. Those galaxies at the furthest edge of the universe ae older.....the ones going away from us. those coming towards us and 'behind' us are younger. Looking to the edge is like looking back in time.

There's no edge to the expanding universe. Just the edge of what we're capable of seeing based on how light travels. No one point in the universe is farther from the center of the universe than any other.

The universe is expanding. Those galaxies at the furthest edge of the universe ae older.....the ones going away from us. those coming towards us and 'behind' us are younger. Looking to the edge is like looking back in time.

There are no galaxies coming towards us. All galaxies are expanding away from all other galaxies. To visualize this, think of spots on a balloon that is being blown up.

The Andromeda galaxy (which is right next door to the Milky Way) is approaching at a speed of about 68 miles per second and arrives in just under 4 billion years. AFAIK, that's the only approaching galaxy of note. We're neighborly enough that gravity is bringing them together at a faster rate than the cosmic expansion is pushing (pulling?) things apart.

I stand corrected. However, what I said is essentially correct other than local fluctuations.

[TiLT]

I realize that it's 250-600 degrees C. Humanity doesn't even output a fraction of that in all but extremely isolated machinery, and you're describing an entire planet with such energy output.

Yes it does. Pretty consistently. Heat is very low energy. That's far less than is required to melt steel.

What heat would this be? You keep talking about it, but you also keep failing to explain what you're talking about.

Where do you think the heat generated by industry (electricity, cars, factories, etc) goes?

Wherever it goes, it's not creating planet-scale heat of 250+ degrees, which is what you keep comparing to.

[noxiousdog]

I realize that it's 250-600 degrees C. Humanity doesn't even output a fraction of that in all but extremely isolated machinery, and you're describing an entire planet with such energy output.

Yes it does. Pretty consistently. Heat is very low energy. That's far less than is required to melt steel.

What heat would this be? You keep talking about it, but you also keep failing to explain what you're talking about.

Where do you think the heat generated by industry (electricity, cars, factories, etc) goes?

Wherever it goes, it's not creating planet-scale heat of 250+ degrees, which is what you keep comparing to.

No, you're doing that comparison. I'm saying it's easily detectable with today's technology. Ergo, we can detect lower energies too which are within a magnitude of the power output of segments of humanity.

[TiLT]

No, you're doing that comparison. I'm saying it's easily detectable with today's technology. Ergo, we can detect lower energies too which are within a magnitude of the power output of segments of humanity.

And I'm saying it's not easily detectable with today's technology. Not even close. We're not even able to detect planets in other solar systems directly (hell, we're struggling detecting planets in our own system, leading to constant debates on whether or not there are more planets in its furthest reaches), and we sure as hell aren't able to detect the energy output of a city on a planet in another solar system. From my understanding of this concept, we observe orbital movement and bending of light around the astral bodies we are able to detect (namely stars) to estimate the location and size of planetary bodies.

You've got a very optimistic view of our current level of technology. As I said, we're essentially blind to other civilizations today.

[Daehawk]

Star wobble.

[Kraken]

No, you're doing that comparison. I'm saying it's easily detectable with today's technology. Ergo, we can detect lower energies too which are within a magnitude of the power output of segments of humanity.

And I'm saying it's not easily detectable with today's technology. Not even close. We're not even able to detect planets in other solar systems directly (hell, we're struggling detecting planets in our own system, leading to constant debates on whether or not there are more planets in its furthest reaches), and we sure as hell aren't able to detect the energy output of a city on a planet in another solar system. From my understanding of this concept, we observe orbital movement and bending of light around the astral bodies we are able to detect (namely stars) to estimate the location and size of planetary bodies.

You've got a very optimistic view of our current level of technology. As I said, we're essentially blind to other civilizations today.

TiLT is right on this one. A planet's artificial infrared emissions would be overwhelmed by reflected starlight, which is in turn washed out by the star's own infrared (heat) emissions.

We can take IR readings of our own planet from orbit because we know the planet's energy budget -- that is, how much sunlight it receives and reflects -- and because the earth isn't lost in the sun's glow. But mostly because we're close enough to take very precise readings.

We might be able to detect point-source radio and x-ray emissions from an extrasolar planet if it's close enough and its star is quiet enough and there aren't big gas clouds between us that absorb and re-emit radiation...but at best infrared lets us estimate a planet's overall temperature.

[Daehawk]

We should also be able to detect lasers if they are pointed just right.....right?

[Kraken]

Depends on their energy and wavelength. Lasers attenuate with distance and scatter if they hit dust, but if a beam were aimed directly at us with enough power we'd see it. They're great for point-to-point communication across a void and might replace radio for deep space missions. It's not something you'd be likely to stumble upon, though.

[Turtle]

Also, realize that you're firing a laser at something that will have moved in the many years it took the light to travel from one solar system to another.

Then, that laser is still just a tiny pinpoint of light in the cosmos that someone has to be watching for.

We barely just got up an always on sky watching satellite up in the last decade.

[Holman]

I think the Fermi question isn't really about civs that are ahead of us but still use conceivable tech like lasers--it's not hard to explain how the vastness of space and time make contact unlikely.

The real question is about civs whose technology is so inconceivably advanced that they make time and distance irrelevant. The universe is old enough that, if such tech is indeed possible, countless such civilizations should have existed by now. (After all, the AI articles also on Wait But Why argue that we--or our descendant artificial beings--will be there in a century.)

Where are those guys?

[Jaymann]

I think the Fermi question isn't really about civs that are ahead of us but still use conceivable tech like lasers--it's not hard to explain how the vastness of space and time make contact unlikely.

The real question is about civs whose technology is so inconceivably advanced that they make time and distance irrelevant. The universe is old enough that, if such tech is indeed possible, countless such civilizations should have existed by now. (After all, the AI articles also on Wait But Why argue that we--or our descendant artificial beings--will be there in a century.)

Where are those guys?

We can't see them through all the post-it notes.

[noxiousdog]

(After all, the AI articles also on Wait But Why argue that we--or our descendant artificial beings--will be there in a century.)

That is a great couple articles. It also makes me wonder if "God" is another civilizations AI.

[noxiousdog]

Just sayin'

"Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy's stars to power computers, space flight, communication, or something we can't yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths," Wright said. "This same basic physics causes your computer to radiate heat while it is turned on."

[El Guapo]

Yo momma's so fat that scientists mistook her for a Kardashev Type III supercivilization.

[Holman]

Just sayin'

"Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy's stars to power computers, space flight, communication, or something we can't yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths," Wright said. "This same basic physics causes your computer to radiate heat while it is turned on."

"Basic physics" don't run the warp drive, Wesley!