< Return to Video

Could we harness the power of a black hole? - Fabio Pacucci

  • Not Synced
    Imagine a distant future when humans
    reach beyond our pale blue dot,
  • Not Synced
    forge cities on planets thousands of
    light-years away,
  • Not Synced
    and maintain a galactic web of trade
    and transport.
  • Not Synced
    What would it take for our civilization
    to make that leap?
  • Not Synced
    There are many things to consider—
    how would we communicate?
  • Not Synced
    What might a galactic government
    look like?
  • Not Synced
    And one of the most fundamental of
    all:
  • Not Synced
    where would we get enough energy
    to power that civilization—
  • Not Synced
    its industry, its terraforming
    operations, and its starships?
  • Not Synced
    An astronomer named Nikolai Kardashev
    proposed a scale
  • Not Synced
    to quantify an evolving civilization’s
    increasing energy needs.
  • Not Synced
    In the first evolutionary stage, which
    we’re currently in,
  • Not Synced
    planet-based fuel sources like fossil
    fuels,
  • Not Synced
    solar panels and nuclear power plants
  • Not Synced
    are probably enough to settle other
    planets inside our own solar system,
  • Not Synced
    but not much beyond that.
  • Not Synced
    For a civilization on the third and final
    stage, expansion on a galactic scale
  • Not Synced
    would require about 100 billion
    times more energy
  • Not Synced
    than the full 385 yotta joules our sun
    releases every second.
  • Not Synced
    Barring a breakthrough in exotic physics,
  • Not Synced
    there’s only one energy source that could
    suffice: a supermassive black hole.
  • Not Synced
    It’s counterintuitive to think of black
    holes as energy sources,
  • Not Synced
    but that’s exactly what they are,
    thanks to their accretion disks:
  • Not Synced
    circular, flat structures formed by matter
    falling into the event horizon.
  • Not Synced
    Because of conservation of angular
    momentum,
  • Not Synced
    particles there don’t just plummet
    straight into the black hole.
  • Not Synced
    Instead, they slowly spiral.
  • Not Synced
    Due to the intense gravitational field
    of the black hole,
  • Not Synced
    these particles convert their potential
    energy to kinetic energy
  • Not Synced
    as they inch closer to the event horizon.
  • Not Synced
    Particle interactions allow for this kinetic
    energy
  • Not Synced
    to be radiated out into space at an
    astonishing matter-to-energy efficiency:
  • Not Synced
    6% for non-rotating black holes, and
    up to 32% for rotating ones.
  • Not Synced
    This drastically outshines
    nuclear fission,
  • Not Synced
    currently the most efficient widely
    available mechanism
  • Not Synced
    to extract energy from mass.
  • Not Synced
    Fission converts just 0.08% of a
    Uranium atom into energy.
  • Not Synced
    The key to harnessing this power
    may lie in a structure
  • Not Synced
    devised by physicist Freeman Dyson,
    known as the Dyson sphere.
  • Not Synced
    In the 1960s, Dyson proposed that an
    advanced planetary civilization
  • Not Synced
    could engineer an artificial sphere
    around their main star,
  • Not Synced
    capturing all of its radiated energy to
    satisfy their needs.
  • Not Synced
    A similar, though vastly more complicated
    design
  • Not Synced
    could theoretically be applied to
    black holes.
  • Not Synced
    In order to produce energy, black holes
    need to be continuously fed –
  • Not Synced
    so we wouldn’t want to fully cover it
    with a sphere.
  • Not Synced
    Even if we did, the plasma jets that shoot
    from the poles
  • Not Synced
    of many supermassive black holes
  • Not Synced
    would blow any structure in
    their way to smithereens.
  • Not Synced
    So instead, we might design a sort of
    Dyson ring,
  • Not Synced
    made of massive, remotely
    controlled collectors.
  • Not Synced
    They’d swarm in an orbit around
    a black hole,
  • Not Synced
    perhaps on the plane of its
    accretion disk, but farther out.
  • Not Synced
    These devices could use mirror-like
    panels
  • Not Synced
    to transmit the collected energy
    to a powerplant,
  • Not Synced
    or a battery for storage.
  • Not Synced
    We’d need to ensure that these collectors
    are built at just the right radius:
  • Not Synced
    too close and they’d melt from
    the radiated energy.
  • Not Synced
    Too far, and they’d only collect a tiny
    fraction of the available energy
  • Not Synced
    and might be disrupted by stars orbiting
    the black hole.
  • Not Synced
    We would likely need several Earths
    worth of highly reflective material
  • Not Synced
    like hematite to construct
    the full system––
  • Not Synced
    plus a few more dismantled planets
    to make a legion of construction robots.
  • Not Synced
    Once built, the Dyson ring would be
    a technological masterpiece,
  • Not Synced
    powering a civilization spread
    across every arm of a galaxy.
  • Not Synced
    This all may seem like wild speculation.
  • Not Synced
    But even now, in our
    current energy crisis,
  • Not Synced
    we’re confronted by the limited
    resources of our planet.
  • Not Synced
    New ways of sustainable energy
    production will always be needed,
  • Not Synced
    especially as humanity works towards
    he survival
  • Not Synced
    and technological progress of our species.
  • Not Synced
    Perhaps there’s already a civilization
    out there
  • Not Synced
    that has conquered these
    astronomical giants.
  • Not Synced
    We may even be able to tell by seeing the
    light from their black hole periodically dim
  • Not Synced
    as pieces of the Dyson ring pass between
    us and them.
  • Not Synced
    Or maybe these superstructures are
    fated to remain in the realm of theory.
  • Not Synced
    Only time––and our scientific
    ingenuity––will tell.
Title:
Could we harness the power of a black hole? - Fabio Pacucci
Speaker:
Fabio Pacucci
Description:

more » « less
Video Language:
English
Team:
closed TED
Project:
TED-Ed
Duration:
05:19

English subtitles

Revisions Compare revisions