Could we harness the power of a black hole? - Fabio Pacucci
-
0:08 - 0:13Imagine a distant future when humans
reach beyond our pale blue dot, -
0:13 - 0:17forge cities on planets
thousands of light-years away, -
0:17 - 0:22and maintain a galactic web
of trade and transport. -
0:22 - 0:25What would it take for our civilization
to make that leap? -
0:25 - 0:28There are many things to consider—
how would we communicate? -
0:28 - 0:31What might a galactic government
look like? -
0:31 - 0:34And one of the most fundamental
of all: -
0:34 - 0:38where would we get enough energy
to power that civilization— -
0:38 - 0:44its industry, its terraforming operations,
and its starships? -
0:44 - 0:48An astronomer named Nikolai Kardashev
proposed a scale -
0:48 - 0:52to quantify an evolving civilization’s
increasing energy needs. -
0:52 - 0:56In the first evolutionary stage,
which we’re currently in, -
0:56 - 1:00planet-based fuel sources
like fossil fuels, -
1:00 - 1:02solar panels and nuclear power plants
-
1:02 - 1:07are probably enough to settle other
planets inside our own solar system, -
1:07 - 1:10but not much beyond that.
-
1:10 - 1:13For a civilization on the third
and final stage, -
1:13 - 1:18expansion on a galactic scale
would require about 100 billion times -
1:18 - 1:26more energy than the full 385 yotta joules
our sun releases every second. -
1:26 - 1:29Barring a breakthrough in exotic physics,
-
1:29 - 1:32there’s only one energy source
that could suffice: -
1:32 - 1:35a supermassive black hole.
-
1:35 - 1:39It’s counterintuitive to think
of black holes as energy sources, -
1:39 - 1:44but that’s exactly what they are,
thanks to their accretion disks: -
1:44 - 1:50circular, flat structures formed
by matter falling into the event horizon. -
1:50 - 1:53Because of conservation
of angular momentum, -
1:53 - 1:57particles there don’t just plummet
straight into the black hole. -
1:57 - 2:00Instead, they slowly spiral.
-
2:00 - 2:04Due to the intense gravitational field
of the black hole, -
2:04 - 2:07these particles convert their potential
energy to kinetic energy -
2:07 - 2:10as they inch closer to the event horizon.
-
2:10 - 2:13Particle interactions allow
for this kinetic energy -
2:13 - 2:15to be radiated out into space
-
2:15 - 2:19at an astonishing matter-to-energy
efficiency: -
2:19 - 2:266% for non-rotating black holes,
and up to 32% for rotating ones. -
2:26 - 2:30This drastically outshines
nuclear fission, -
2:30 - 2:33currently the most efficient
widely available mechanism -
2:33 - 2:35to extract energy from mass.
-
2:35 - 2:42Fission converts just 0.08%
of a Uranium atom into energy. -
2:42 - 2:46The key to harnessing this power
may lie in a structure -
2:46 - 2:52devised by physicist Freeman Dyson,
known as the Dyson sphere. -
2:52 - 2:57In the 1960s, Dyson proposed
that an advanced planetary civilization -
2:57 - 3:01could engineer an artificial sphere
around their main star, -
3:01 - 3:06capturing all of its radiated energy
to satisfy their needs. -
3:06 - 3:09A similar, though vastly
more complicated design -
3:09 - 3:13could theoretically be applied
to black holes. -
3:13 - 3:17In order to produce energy,
black holes need to be continuously fed— -
3:17 - 3:21so we wouldn’t want to fully cover
it with a sphere. -
3:21 - 3:24Even if we did, the plasma jets
that shoot from the poles -
3:24 - 3:26of many supermassive black holes
-
3:26 - 3:30would blow any structure
in their way to smithereens. -
3:30 - 3:34So instead, we might design
a sort of Dyson ring, -
3:34 - 3:37made of massive,
remotely controlled collectors. -
3:37 - 3:40They’d swarm in an orbit
around a black hole, -
3:40 - 3:44perhaps on the plane
of its accretion disk, but farther out. -
3:44 - 3:47These devices could use
mirror-like panels -
3:47 - 3:50to transmit the collected energy
to a powerplant, -
3:50 - 3:53or a battery for storage.
-
3:53 - 3:58We’d need to ensure that these collectors
are built at just the right radius: -
3:58 - 4:01too close and they’d melt
from the radiated energy. -
4:01 - 4:06Too far, and they’d only collect
a tiny fraction of the available energy -
4:06 - 4:09and might be disrupted by stars orbiting
the black hole. -
4:09 - 4:14We would likely need several Earths
worth of highly reflective material -
4:14 - 4:17like hematite to construct
the full system— -
4:17 - 4:23plus a few more dismantled planets
to make a legion of construction robots. -
4:23 - 4:27Once built, the Dyson ring
would be a technological masterpiece, -
4:27 - 4:32powering a civilization spread
across every arm of a galaxy. -
4:32 - 4:35This all may seem like wild speculation.
-
4:35 - 4:38But even now,
in our current energy crisis, -
4:38 - 4:42we’re confronted
by the limited resources of our planet. -
4:42 - 4:46New ways of sustainable energy
production will always be needed, -
4:46 - 4:49especially as humanity works
towards the survival -
4:49 - 4:52and technological progress of our species.
-
4:52 - 4:55Perhaps there’s already a civilization
out there -
4:55 - 4:58that has conquered
these astronomical giants. -
4:58 - 5:00We may even be able to tell
-
5:00 - 5:04by seeing the light
from their black hole periodically dim -
5:04 - 5:08as pieces of the Dyson ring pass
between us and them. -
5:08 - 5:13Or maybe these superstructures are fated
to remain in the realm of theory. -
5:13 - 5:17Only time— and our scientific ingenuity—
will tell.
- Title:
- Could we harness the power of a black hole? - Fabio Pacucci
- Speaker:
- Fabio Pacucci
- Description:
-
View full lesson: https://ed.ted.com/lessons/could-we-harness-the-power-of-a-black-hole-fabio-pacucci
Imagine a distant future when humans reach beyond Earth, forge cities on planets thousands of light-years away, and maintain a galactic web of trade and transport. What would it take to make that leap? And where would we get enough energy to power that civilization? Fabio Pacucci explores the possibility of harnessing energy from a black hole to power a galactic civilization.
Lesson by Fabio Pacucci, directed by TOTEM Studio.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 05:19
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