(B) Fermi - Where is Everybody?
Enrico Fermi (1901 - 1954)
This was written by Tim Urban 21 May 2014, from
here (along with plenty more good stuff) ==>
And here we have a Jan 2016 update ==>
and, equally amazing, we have this ==>
It turns out that roughly 68% of the universe is dark
energy. Dark matter makes up about 27%. The rest -
everything on Earth, everything ever observed with all of
our instruments, all normal matter - adds up to less than 5%
of the universe.
See more at ==>
Everyone feels
something when they’re in a really good starry place
on a really good starry night and they look up and
see this stunning picture (right)
Some people stick with the traditional,
feeling struck by the epic beauty or blown away by
the insane scale of the universe. Personally, I go
for the old “existential meltdown followed by acting
weird for the next half hour.” But everyone feels
something.
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Physicist Enrico Fermi felt something too - ”Where
is everybody?”
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A really starry sky seems vast—but all we’re
looking at is our very local neighborhood. On the
very best nights, we can see up to about 2,500 stars
(roughly one hundred-millionth of the stars in our
galaxy), and almost all of them are less than 1,000
light years away from us (or 1% of the diameter of
the Milky Way). So what we’re really looking at is
this (left image)
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When confronted with the topic of stars and galaxies, a
question that tantalizes most humans is, “Is there other
intelligent life out there?” Let’s put some numbers to it -
As many stars as there are in our galaxy (100 – 400
billion), there are roughly an equal number of galaxies in
the observable universe—so for every star in the colossal
Milky Way, there’s a whole galaxy out there. All together,
that comes out to the typically quoted range of between 1022
and 1024 total stars, which means that for every grain of
sand on Earth, there are 10,000 stars out there.
The science world isn’t in total agreement about what
percentage of those stars are “sun-like” (similar in size,
temperature, and luminosity)—opinions typically range from
5% to 20%. Going with the most conservative side of that
(5%), and the lower end for the number of total stars
(1022), gives us 500 quintillion, or 500 billion billion
sun-like stars.
There’s also a debate over what percentage of those
sun-like stars might be orbited by an Earth-like planet (one
with similar temperature conditions that could have liquid
water and potentially support life similar to that on
Earth). Some say it’s as high as 50%, but let’s go with the
more conservative 22% that came out of a recent PNAS study.
That suggests that there’s a potentially-habitable
Earth-like planet orbiting at least 1% of the total stars in
the universe—a total of 100 billion billion Earth-like
planets.
So there are (at least) 100
Earth-like planets for every grain of sand in the world.
Think about that next time you’re on the beach.
Moving forward, we have no choice but to get completely
speculative. Let’s imagine that after billions of years in
existence, 1% of Earth-like planets develop life (if that’s
true, every grain of sand would represent one planet with
life on it). And imagine that on 1% of those planets, the
life advances to an intelligent level like it did here on
Earth. That would mean there were 10 quadrillion, or 10
million billion intelligent civilizations in the observable
universe.
Moving back to just our galaxy, and doing the same math on
the lowest estimate for stars in the Milky Way (100
billion), we’d estimate that there are 1 billion Earth-like
planets and 100,000 intelligent civilizations in our
galaxy.[1]
SETI (Search for Extraterrestrial Intelligence) is an
organization dedicated to listening for signals from other
intelligent life. If we’re right that there are 100,000 or
more intelligent civilizations in our galaxy, and even a
fraction of them are sending out radio waves or laser beams
or other modes of attempting to contact others, shouldn’t
SETI’s satellite array pick up all kinds of signals?
But it hasn’t. Not one.
Ever. So, ”Where is
everybody?”
It gets stranger. Our sun is relatively
young in the lifespan of the universe. There are
far older stars with far older Earth-like planets,
which should in theory mean civilizations far more
advanced than our own. As an example, let’s
compare our 4.54 billion-year-old Earth to a
hypothetical 8 billion-year-old Planet X.
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If Planet X has a similar story to Earth, let’s
look at where their civilization would be today,
using the orange time-span as a reference to show
how huge the green time-span is - (left image)
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The technology and knowledge of a
civilization only 1,000 years ahead of us could be
as shocking to us as our world would be to a
medieval person. A civilization 1 million years
ahead of us might be as incomprehensible to us as
human culture is to chimpanzees. And Planet XDyson
Sphere is 3.4 billion years ahead of us…
There’s something called The Kardashev Scale,
which helps us group intelligent civilizations
into three broad categories by the amount of
energy they use:
A Type I Civilization has the ability to use all
of the energy from their sun that falls on their
planet. We’re not quite a Type I Civilization, but
we’re close (Carl Sagan created a formula for this
scale which puts us at a Type 0.7 Civilization).
A Type II Civilization can harness all of the
energy of their host star. Our feeble Type I
brains can hardly imagine how someone would do
this, but we’ve tried our best, imagining things
like a Dyson Sphere.
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A Type III Civilization blows the other two
away, accessing power comparable to that emitted
of all of the suns of their galaxy, or for us, the
entire Milky Way galaxy.
If this level of advancement sounds hard to
believe, remember Planet X above and their 3.4
billion years of further development. If a
civilization on Planet X were similar to ours and
were able to survive all the way to Type III
level, the natural thought is that they’d probably
have mastered inter-stellar travel by now,
possibly even colonizing the entire galaxy.
One hypothesis as to how galactic colonization
could happen is by creating machinery that can
travel to other planets, spend 500 years or so
self-replicating using the raw materials on their
new planet, and then send two replicas off to do
the same thing. Even without traveling anywhere
near the speed of light, this process would
colonize the whole galaxy in 3.75 million years, a
relative blink of an eye when talking in the scale
of billions of years: (left image)
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Continuing to speculate, if 1% of intelligent
life survives long enough to become a potentially
galaxy-colonizing Type III Civilization, our
calculations above suggest that there should be at
least 1,000 Type III Civilizations in our galaxy
alone — and given the power of such a
civilization, their presence would likely be
pretty noticeable. And yet, we see nothing, hear
nothing, and we’re visited by no one.
So where is everybody?
We have no answer to the Fermi Paradox — the
best we can do is “possible explanations.” And if
you ask ten different scientists what their hunch
is about the correct one, you’ll get ten different
answers. You know when you hear about humans of
the past debating whether the Earth was round or
if the sun revolved around the Earth or thinking
that lightning happened because of Zeus, and they
seem so primitive and in the dark? That’s about
where we are with this topic.
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In taking a look at some of the most-discussed
possible explanations for the Fermi Paradox, let’s
divide them into two broad categories—those
explanations which assume that there’s no sign of
Type II and Type III Civilizations because there
are none of them out there, and those which assume
they’re out there and we’re not seeing or hearing
anything for other reasons:
Explanation Group 1: There are no signs of higher
(Type II and III) civilizations because there are
no higher civilizations in existence.
Those who subscribe to Group 1 explanations point
to something called the non-exclusivity problem,
which rebuffs any theory that says, “There are
higher civilizations, but none of them have made
any kind of contact with us because they all
_____.” Group 1 people look at the math, which
says there should be so many thousands (or
millions) of higher civilizations, that at least
one of them would be an exception to the rule.
Even if a theory held for 99.99% of higher
civilizations, the other .01% would behave
differently and we’d become aware of their
existence.
Therefore, say Group 1 explanations, it must be
that there are no super-advanced civilizations.
And since the math suggests that there are
thousands of them just in our own galaxy,
something else must be going on.
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This something else is called The Great Filter.
The Great Filter theory says that at some point from
pre-life to Type III intelligence, there’s a wall that all
or nearly all attempts at life hit. There’s some stage in
that long evolutionary process that is extremely unlikely
or impossible for life to get beyond. That stage is The
Great Filter.
If this theory is true, the big question
is, Where in the timeline does the Great Filter
occur?
It turns out that when it comes to the fate of
humankind, this question is very important.
Depending on where The Great Filter occurs, we’re
left with three possible realities:
We’re rare, we’re
first, or we’re fucked.
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1. We’re Rare (The Great Filter is Behind Us)
One hope we have is that The Great Filter is behind
us—we managed to surpass it, which would mean it’s
extremely rare for life to make it to our level of
intelligence. The diagram below shows only two species
making it past, and we’re one of them.
The GREAT FILTER is
BEHIND US
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This scenario would explain why there are no
Type III Civilizations…but it would also mean that
we could be one of the few exceptions now that
we’ve made it this far.
It would mean we have hope. On the surface, this
sounds a bit like people 500 years ago suggesting
that the Earth is the center of the universe - it
implies that we’re special.
However, something scientists call “observation
selection effect” suggests that anyone who is
pondering their own rarity is inherently part of
an intelligent life “success story” -
and whether they’re actually rare or quite common,
the thoughts they ponder and conclusions they draw
will be identical. This forces us to admit that
being special is at least a possibility.
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And if we are special, when
exactly did we become special—i.e. which step did we
surpass that almost everyone else gets stuck on?
One possibility: The Great Filter could be at the very
beginning—it might be incredibly unusual for life to begin
at all. This is a candidate because it took about a
billion years of Earth’s existence to finally happen, and
because we have tried extensively to replicate that event
in labs and have never been able to do it. If this is
indeed The Great Filter, it would mean that not only is
there no intelligent life out there, there may be no other
life at all.
Another possibility: The Great Filter could be the jump
from the simple prokaryote cell to the complex eukaryote
cell. After prokaryotes came into being, they remained
that way for almost two billion years before making the
evolutionary jump to being complex and having a nucleus.
If this is The Great Filter, it would mean the universe is
teeming with simple prokaryote cells and almost nothing
beyond that.
There are a number of other possibilities—some even think
the most recent leap we’ve made to our current
intelligence is a Great Filter candidate. While the leap
from semi-intelligent life (chimps) to intelligent life
(humans) doesn’t at first seem like a miraculous step,
Steven Pinker rejects the idea of an inevitable “climb
upward” of evolution: “Since evolution does not strive for
a goal but just happens, it uses the adaptation most
useful for a given ecological niche, and the fact that, on
Earth, this led to technological intelligence only once so
far may suggest that this outcome of natural selection is
rare and hence by no means a certain development of the
evolution of a tree of life.”
Most leaps do not qualify as Great Filter candidates. Any
possible Great Filter must be one-in-a-billion type thing
where one or more total freak occurrences need to happen
to provide a crazy exception—for that reason, something
like the jump from single-cell to multi-cellular life is
ruled out, because it has occurred as many as 46 times, in
isolated incidents, just on this planet alone. For the
same reason, if we were to find a fossilized eukaryote
cell on Mars, it would rule the above “simple-to-complex
cell” leap out as a possible Great Filter (as well as
anything before that point on the evolutionary
chain)—because if it happened on both Earth and Mars, it’s
almost definitely not a one-in-a-billion freak occurrence.
If we are indeed rare, it could be because of a fluky
biological event, but it also could be attributed to what
is called the Rare Earth Hypothesis, which suggests that
though there may be many Earth-like planets, the
particular conditions on Earth—whether related to the
specifics of this solar system, its relationship with the
moon (a moon that large is unusual for such a small planet
and contributes to our particular weather and ocean
conditions), or something about the planet itself—are
exceptionally friendly to life.
2. We’re the First - Are we the First?
For Group 1 Thinkers, if the Great Filter is not behind
us, the one hope we have is that conditions in the
universe are just recently, for the first time since the
Big Bang, reaching a place that would allow intelligent
life to develop. In that case, we and many other species
may be on our way to super-intelligence, and it simply
hasn’t happened yet. We happen to be here at the right
time to become one of the first super-intelligent
civilizations.
One example of a phenomenon that could make this
realistic is the prevalence of gamma-ray bursts,
insanely huge explosions that we’ve observed in
distant galaxies. In the same way that it took the
early Earth a few hundred million years before the
asteroids and volcanoes died down and life became
possible, it could be that the first chunk of the
universe’s existence was full of cataclysmic
events like gamma-ray bursts that would incinerate
everything nearby from time to time and prevent
any life from developing past a certain stage.
Now, perhaps, we’re in the midst of an
astrobiological phase transition and this is the
first time any life has been able to evolve for
this long, uninterrupted.
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3. We’re Fucked (The Great Filter is Ahead of Us)
If we’re neither rare nor early, Group 1 thinkers
conclude that The Great Filter must be in our future. This
would suggest that life regularly evolves to where we are,
but that something prevents life from going much further
and reaching high intelligence in almost all cases—and
we’re unlikely to be an exception.
The GREAT FILTER is
AHEAD of US
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One possible future is a regularly-occurring
cataclysmic natural event, like the
above-mentioned gamma-ray bursts, except they’re
unfortunately not done yet and it’s just a matter
of time before all life on Earth is suddenly wiped
out by one. Another candidate is the possible
inevitability that nearly all intelligent
civilizations end up destroying themselves once a
certain level of technology is reached.
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This is why Oxford University philosopher Nick Bostrom
says that “no news is good news.” The discovery of even
simple life on Mars would be devastating, because it would
cut out a number of potential Great Filters behind us. And
if we were to find fossilized complex life on Mars,
Bostrom says “it would be by far the worst news ever
printed on a newspaper cover,” because it would mean The
Great Filter is almost definitely ahead of us—ultimately
dooming the species. Bostrom believes that when it comes
to The Fermi Paradox, “the silence of the night sky is
golden.”
Explanation Group 2: Type II
and III intelligent civilizations are out there—and there
are logical reasons why we might not have heard from them.
Group 2 explanations
get rid of any notion that we’re rare or special or the
first at anything—on the contrary, they believe in the
Mediocrity Principle, whose starting point is that there
is nothing unusual or rare about our galaxy, solar system,
planet, or level of intelligence, until evidence proves
otherwise. They’re also much less quick to assume that the
lack of evidence of higher intelligence beings is evidence
of their nonexistence—emphasizing the fact that our search
for signals stretches only about 100 light years away from
us (0.1% across the galaxy) and suggesting a number of
possible explanations. Here are 10:
Possibility 1)
Super-intelligent life could very well have already
visited Earth, but before we were here. In the scheme of
things, sentient humans have only been around for about
50,000 years, a little blip of time. If contact happened
before then, it might have made some ducks flip out and
run into the water and that’s it. Further, recorded
history only goes back 5,500 years—a group of ancient
hunter-gatherer tribes may have experienced some crazy
alien shit, but they had no good way to tell anyone in the
future about it.
Possibility 2)
The galaxy has been colonized, but we just live in some
desolate rural area of the galaxy. The Americas may have
been colonized by Europeans long before anyone in a small
Inuit tribe in far northern Canada realized it had
happened. There could be an urbanization component to the
interstellar dwellings of higher species, in which all the
neighboring solar systems in a certain area are colonized
and in communication, and it would be impractical and
purposeless for anyone to deal with coming all the way out
to the random part of the spiral where we live.
Possibility 3)
The entire concept of physical colonization is a
hilariously backward concept to a more advanced species.
Remember the picture of the Type II Civilization above
with the sphere around their star? With all that energy,
they might have created a perfect environment for
themselves that satisfies their every need. They might
have crazy-advanced ways of reducing their need for
resources and zero interest in leaving their happy utopia
to explore the cold, empty, undeveloped universe.
An even more advanced civilization might view the entire
physical world as a horribly primitive place, having long
ago conquered their own biology and uploaded their brains
to a virtual reality, eternal-life paradise. Living in the
physical world of biology, mortality, wants, and needs
might seem to them the way we view primitive ocean species
living in the frigid, dark sea. FYI, thinking about
another life form having bested mortality makes me
incredibly jealous and upset. We need more Afterlife
research.
Possibility 4)
There are scary predator civilizations out there, and
most intelligent life knows better than to broadcast any
outgoing signals and advertise their location. This is an
unpleasant concept and would help explain the lack of any
signals being received by the SETI satellites. It also
means that we might be the super naive newbies who are
being unbelievably stupid and risky by ever broadcasting
outward signals. There’s a debate going on currently about
whether we should engage in METI (Messaging to
Extraterrestrial Intelligence—the reverse of SETI) or not,
and most people say we should not. Stephen Hawking warns,
“If aliens visit us, the outcome would be much as when
Columbus landed in America, which didn’t turn out well for
the Native Americans.” Even Carl Sagan (a general believer
that any civilization advanced enough for interstellar
travel would be altruistic, not hostile) called the
practice of METI “deeply unwise and immature,” and
recommended that “the newest children in a strange and
uncertain cosmos should listen quietly for a long time,
patiently learning about the universe and comparing notes,
before shouting into an unknown jungle that we do not
understand.” Scary.[2]
Possibility 5)
There’s only one instance of higher-intelligent life—a
“superpredator” civilization (like humans are here on
Earth)—who is far more advanced than everyone else and
keeps it that way by exterminating any intelligent
civilization once they get past a certain level. This
would suck. The way it might work is that it’s an
inefficient use of resources to exterminate all emerging
intelligences, maybe because most die out on their own.
But past a certain point, the super beings make their
move—because to them, an emerging intelligent species
becomes like a virus as it starts to grow and spread. This
theory suggests that whoever was the first in the galaxy
to reach intelligence won, and now no one else has a
chance. This would explain the lack of activity out there
because it would keep the number of super-intelligent
civilizations to just one.
Possibility 6)
There’s plenty of activity and noise out there, but our
technology is too primitive and we’re listening for the
wrong things. Like walking into a modern-day office
building, turning on a walkie-talkie, and when you hear no
activity (which of course you wouldn’t hear because
everyone’s texting, not using walkie-talkies), determining
that the building must be empty. Or maybe, as Carl Sagan
has pointed out, it could be that our minds work
exponentially faster or slower than another form of
intelligence out there—e.g. it takes them 12 years to say
“Hello,” and when we hear that communication, it just
sounds like white noise to us.
Possibility 7)
We are receiving contact from other intelligent life,
but the government is hiding it. This is an idiotic
theory, but I had to mention it because it’s talked about
so much.
Possibility 8)
Higher civilizations are aware of us and observing us
(AKA the “Zoo Hypothesis”). As far as we know,
super-intelligent civilizations exist in a
tightly-regulated galaxy, and our Earth is treated like
part of a vast and protected national park, with a strict
“Look but don’t touch” rule for planets like ours. We
wouldn’t notice them, because if a far smarter species
wanted to observe us, it would know how to easily do so
without us realizing it. Maybe there’s a rule similar to
the Star Trek's Prime Directive which prohibits
super-intelligent beings from making any open contact with
lesser species like us or revealing themselves in any way,
until the lesser species has reached a certain level of
intelligence.
Possibility 9)
Higher civilizations are here, all around us. But we’re
too primitive to perceive them. Michio Kaku sums it up
like this:
Let's say we have an ant hill in the middle of the forest.
And right next to the ant hill, they’re building a
ten-lane super-highway. And the question is “Would the
ants be able to understand what a ten-lane super-highway
is? Would the ants be able to understand the technology
and the intentions of the beings building the highway next
to them?
So it’s not that we can’t
pick up the signals from Planet X using our technology,
it’s that we can’t even comprehend what the beings from
Planet X are or what they’re trying to do. It’s so beyond
us that even if they really wanted to enlighten us, it
would be like trying to teach ants about the internet.
Along those lines, this may also be an answer to “Well if
there are so many fancy Type III Civilizations, why
haven’t they contacted us yet?” To answer that, let’s ask
ourselves — when Pizarro made his way into Peru, did he
stop for a while at an anthill to try to communicate? Was
he magnanimous, trying to help the ants in the anthill?
Did he become hostile and slow his original mission down
in order to smash the anthill apart? Or was the anthill of
complete and utter and eternal irrelevance to Pizarro?
That might be our situation here.
Possibility 10)
We’re completely wrong about our reality. There are a
lot of ways we could just be totally off with everything
we think. The universe might appear one way and be
something else entirely, like a hologram. Or maybe we’re
the aliens and we were planted here as an experiment or as
a form of fertilizer. There’s even a chance that we’re all
part of a computer simulation by some researcher from
another world, and other forms of life simply weren’t
programmed into the simulation.
As we continue along with our possibly-futile search for
extraterrestrial intelligence, I’m not really sure what
I’m rooting for. Frankly, learning either that we’re
officially alone in the universe or that we’re officially
joined by others would be creepy, which is a theme with
all of the surreal story-lines listed above—whatever the
truth actually is, it’s mind-blowing.
Beyond its shocking science fiction component, The Fermi
Paradox also leaves me with a deep humbling. Not just the
normal “Oh yeah, I’m microscopic and my existence lasts
for three seconds” humbling that the universe always
triggers. The Fermi Paradox brings out a sharper, more
personal humbling, one that can only happen after spending
hours of research hearing your species’ most renowned
scientists present insane theories, change their minds
again and again, and wildly contradict each other —
reminding us that future generations will look at us the
same way we see the ancient people who were sure that the
stars were the underside of the dome of heaven, and
they’ll think “Wow they really had no idea what was going
on.”
Compounding all of this is the blow to our species’
self-esteem that comes with all of this talk about Type II
and III Civilizations. Here on Earth, we’re the king of
our little castle, proud ruler of the huge group of
imbeciles who share the planet with us. And in this bubble
with no competition and no one to judge us, it’s rare that
we’re ever confronted with the concept of being a
dramatically inferior species to anyone. But after
spending a lot of time with Type II and III Civilizations
over the past week, our power and pride are seeming soft
and self-deluding.
That said, given that my normal outlook is that humanity
is a lonely orphan on a tiny rock in the middle of a
desolate universe, the humbling fact that we’re probably
not as smart as we think we are, and the possibility that
a lot of what we’re sure about might be wrong, sounds
wonderful. It opens the door just a crack that maybe, just
maybe, there might be more to the story than we realize.
And here we have a Jan 2016 update ==>
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Enrico Fermi (1901 - 1954)
Enrico Fermi was an Italian–American
physicist and the creator of the world's first
nuclear reactor, the Chicago Pile-1. He has been
called the "architect of the nuclear age" and
the "architect of the atomic bomb". He was one
of very few physicists to excel in both
theoretical physics and experimental physics.
Fermi held several patents related to the use of
nuclear power, and was awarded the 1938 Nobel
Prize in Physics for his work on induced
radioactivity by neutron bombardment and for the
discovery of trans-uranium elements. He made
significant contributions to the development of
statistical mechanics, quantum theory, and
nuclear and particle physics. And much more.
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