WEBVTT

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Many generations have felt 
they've reached the pinnacle

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of technological advancement,

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yet look back 100 years,

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and the technologies 
we take for granted today

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would seem like impossible magic.

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So will there be a point

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where we reach an actual limit 
of technological progress?

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And if so, are we anywhere near
that limit now?

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Half a century ago,

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Russian astronomer Nikolai Kardashev
was asking similar questions

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when he came up with a way
to measure technological progress,

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even when we have no idea exactly
what it might look like.

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Anything we do in the future
will require energy,

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so Kardashev's scale
classifies potential civilizations,

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whether alien civilizations out there
in the universe or our own,

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into three levels based 
on energy consumption.

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The tiny amount of energy
we currently consume

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pales next to what we leave untapped.

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A Type I, or planetary civilization,

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can access all the energy resources
of its home planet.

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In our case, this is the 174,000
terawatts Earth receives from the Sun.

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We currently only harness 
about 15 terawatts of it,

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mostly by burning solar energy
stored in fossil fuels.

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To approach becoming 
a Type I civilization,

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we would need to capture solar energy
more directly and efficiently

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by covering the planet with solar panels.

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Based on the most optimistic models,

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we might get there 
within just four centuries.

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What would be next?

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Well, the Earth only gets a sliver
of the Sun's energy,

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while the rest of its 400 yottawatts
is wasted in dead space.

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But a Type II, or stellar civilization,

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would make the most 
of its home star's energy.

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Instead of installing solar panels
around a planet,

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a Type II civilization would install them
directly orbiting its star,

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forming a theoretical structure
called a Dyson sphere.

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And the third step?

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A Type III civilization would harness
all the energy of its home galaxy.

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But we can also think of progress
in the opposite way.

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How small can we go?

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To that end, British cosmologist
John Barrow

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classified civilizations by the size
of objects they control.

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That ranges from mechanical structures
at our own scale,

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to the building blocks of our own biology,

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down to unlocking atoms themselves.

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We've currently touched the atomic level,
though our control remains limited.

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But we potentially could 
go much smaller in the future.

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To get a sense of the extent 
to which that's true,

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the observable universe is 26 orders 
of magnitude larger than a human body.

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That means if you zoomed out
by a factor of ten 26 times,

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you'd be at the scale of the universe.

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But to reach the minimum length scale,
known as the Planck length,

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you would need to zoom in 35 times.

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As physicist Richard Feynman once said,
"There's plenty of room at the bottom."

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Instead of one or the other,

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it's likely that our civilization will
continue to develop

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along both Kardashev and Barrow scales.

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Precision on a smaller scale lets us
use energy more efficiently

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and unlocks new energy sources,
like nuclear fusion,

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or even antimatter.

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And this increased energy lets us
expand and build on a larger scale.

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A truly advanced civilization, then,

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would harness both stellar energy
and subatomic technologies.

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But these predictions weren't made
just for us humans.

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They double as a possible means

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of detecting intelligent life 
in the universe.

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If we find a Dyson sphere 
around a distant star,

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that's a pretty compelling sign of life.

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Or, what if, instead of a structure that
passively soaked up all the star's energy,

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like a plant,

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an alien civilization built one that 
actively sucked the energy out of the star

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like a hummingbird.

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Frighteningly enough, we've observed
super dense celestial bodies

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about the size of a planet

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that drain energy out 
of a much bigger star.

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It would be much too premature to conclude

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that this is evidence 
of life in the universe.

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There are also explanations 
for these observations

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that don't involve alien life forms.

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But that doesn't stop us 
from asking, "What if?"