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The Physics of Extra-Terrestrial Civilizations fwded by DGW.

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  • Darren-George: Walker
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    Message 1 of 1 , Oct 6, 2003
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      > The Physics of Extra-Terrestrial Civilizations
      > How advanced could they possibly be?
      > By Michio Kaku
      > http://www.mkaku.org/articles/physics_of_alien_civs.shtml
      >
      >
      > The late Carl Sagan once asked this question, "What does it mean for a
      > civilization to be a million years old? We have had radio telescopes and
      > spaceships for a few decades; our technical civilization is a few hundred
      > years old... an advanced civilization millions of years old is as much
      > beyond us as we are beyond a bush baby or a macaque."
      >
      > Although any conjecture about such advanced civilizations is a matter of
      > sheer speculation, one can still use the laws of physics to place upper
      and
      > lower limits on these civilizations. In particular, now that the laws of
      > quantum field theory, general relativity, thermodynamics, etc. are fairly
      > well-established, physics can impose broad physical bounds which constrain
      > the parameters of these civilizations.
      >
      > This question is no longer a matter of idle speculation. Soon, humanity
      may
      > face an existential shock as the current list of a dozen Jupiter-sized
      > extra-solar planets swells to hundreds of earth-sized planets, almost
      > identical twins of our celestial homeland. This may usher in a new era in
      > our relationship with the universe: we will never see the night sky in the
      > same way ever again, realizing that scientists may eventually compile an
      > encyclopedia identifying the precise co-ordinates of perhaps hundreds of
      > earth-like planets.
      >
      > Today, every few weeks brings news of a new Jupiter-sized extra-solar
      planet
      > being discovered, the latest being about 15 light years away orbiting
      around
      > the star Gliese 876. The most spectacular of these findings was
      photographed
      > by the Hubble Space Telescope, which captured breathtaking photos of a
      > planet 450 light years away being sling-shot into space by a double-star
      > system.
      >
      > But the best is yet to come. Early in the next decade, scientists will
      > launch a new kind of telescope, the interferome try space telescope, which
      > uses the interference of light beams to enhance the resolving power of
      > telescopes.
      >
      > For example, the Space Interferometry Mission (SIM), to be launched early
      in
      > the next decade, consists of multiple telescopes placed along a 30 foot
      > structure. With an unprecedented resolution approaching the physical
      limits
      > of optics, the SIM is so sensitive that it almost defies belief: orbiting
      > the earth, it can detect the motion of a lantern being waved by an
      astronaut
      > on Mars!
      >
      > The SIM, in turn, will pave the way for the Terrestrial Planet Finder, to
      be
      > launched late in the next decade, which should identify even more
      earth-like
      > planets. It will scan the brightest 1,000 stars within 50 light years of
      the
      > earth and will focus on the 50 to 100 brightest planetary systems.
      >
      > All this, in turn, will stimulate an active effort to determine if any of
      > them harbor life, perhaps some with civilizations more advanced than ours.
      >
      > Although it is impossible to predict the precise features of such advanced
      > civilizations, their broad outlines can be analyzed using the laws of
      > physics. No matter how many millions of years separate us from them, they
      > still must obey the iron laws of physics, which are now advanced enough to
      > explain everything from sub-atomic particles to the large-scale structure
      of
      > the universe, through a staggering 43 orders of magnitude.
      >
      >
      > Physics of Type I, II, and III Civilizations
      >
      > Specifically, we can rank civilizations by their energy consumption, using
      > the following principles:
      >
      > 1) The laws of thermodynamics. Even an advanced civilization is bound by
      the
      > laws of thermodynamics, especially the Second Law, and can hence be ranked
      > by the energy at their disposal.
      >
      > 2) The laws of stable matter. Baryonic matter (e.g. based on protons and
      > neutrons) tends to clump into three large groupings: planets, stars and
      > galaxies. (This is a well-defined by product of stellar and galactic
      > evolution, thermonuclear fusion, etc.) Thus, their energy will also be
      based
      > on three distinct types, and this places upper limits on their rate of
      > energy consumption.
      >
      > 3) The laws of planetary evolution. Any advanced civilization must grow in
      > energy consumption faster than the frequency of life-threatening
      > catastrophes (e.g. meteor impacts, ice ages, supernovas, etc.). If they
      grow
      > any slower, they are doomed to extinction. This places mathematical lower
      > limits on the rate of growth of these civilizations.
      >
      > In a seminal paper published in 1964 in the Journal of Soviet Astronomy,
      > Russian astrophysicist Nicolai Kardashev theorized that advanced
      > civilizations must therefore be grouped according to three types: Type I,
      > II, and III, which have mastered planetary, stellar and galactic forms of
      > energy, respectively. He calculated that the energy consumption of these
      > three types of civilization would be separated by a factor of many
      billions.
      > But how long will it take to reach Type II and III status?
      >
      >
      > Shorter than most realize.
      >
      > Berkeley astronomer Don Goldsmith reminds us that the earth receives about
      > one billionth of the suns energy, and that humans utilize about one
      > millionth of that. So we consume about one million billionth of the suns
      > total energy. At present, our entire planetary energy production is about
      10
      > billion billion ergs per second. But our energy growth is rising
      > exponentially, and hence we can calculate how long it will take to rise to
      > Type II or III status.
      >
      > Goldsmith says, "Look how far we have come in energy uses once we figured
      > out how to manipulate energy, how to get fossil fuels really going, and
      how
      > to create electrical power from hydropower, and so forth; we've come up in
      > energy uses in a remarkable amount in just a couple of centuries compared
      to
      > billions of years our planet has been here ... and this same sort of thing
      > may apply to other civilizations."
      >
      > Physicist Freeman Dyson of the Institute for Advanced Study estimates
      that,
      > within 200 years or so, we should attain Type I status. In fact, growing
      at
      > a modest rate of 1% per year, Kardashev estimated that it would take only
      > 3,200 years to reach Type II status, and 5,800 years to reach Type III
      > status.
      >
      >
      > Living in a Type I,II, or III civilization
      >
      > For example, a Type I civilization is a truly planetary one, which has
      > mastered most forms of planetary energy. Their energy output may be on the
      > order of thousands to millions of times our current planetary output. Mark
      > Twain once said, "Everyone complains about the weather, but no one does
      > anything about it." This may change with a Type I civilization, which has
      > enough energy to modify the weather. They also have enough energy to alter
      > the course of earthquakes, volcanoes, and build cities on their oceans.
      >
      > Currently, our energy output qualifies us for Type 0 status. We derive our
      > energy not from harnessing global forces, but by burning dead plants (e.g.
      > oil and coal). But already, we can see the seeds of a Type I civilization.
      > We see the beginning of a planetary language (English), a planetary
      > communication system (the Internet), a planetary economy (the forging of
      the
      > European Union), and even the beginnings of a planetary culture (via mass
      > media, TV, rock music, and Hollywood films).
      >
      > By definition, an advanced civilization must grow faster than the
      frequency
      > of life-threatening catastrophes. Since large meteor and comet impacts
      take
      > place once every few thousand years, a Type I civilization must master
      space
      > travel to deflect space debris within that time frame, which should not be
      > much of a problem. Ice ages may take place on a time scale of tens of
      > thousands of years, so a Type I civilization must learn to modify the
      > weather within that time frame.
      >
      > Artificial and internal catastrophes must also be negotiated. But the
      > problem of global pollution is only a mortal threat for a Type 0
      > civilization; a Type I civilization has lived for several millennia as a
      > planetary civilization, necessarily achieving ecological planetary
      balance.
      > Internal problems like wars do pose a serious recurring threat, but they
      > have thousands of years in which to solve racial, national, and sectarian
      > conflicts.
      >
      > Eventually, after several thousand years, a Type I civilization will
      exhaust
      > the power of a planet, and will derive their energy by consuming the
      entire
      > output of their suns energy, or roughly a billion trillion trillion ergs
      per
      > second.
      >
      > With their energy output comparable to that of a small star, they should
      be
      > visible from space. Dyson has proposed that a Type II civilization may
      even
      > build a gigantic sphere around their star to more efficiently utilize its
      > total energy output. Even if they try to conceal their existence, they
      must,
      > by the Second Law of Thermodynamics, emit waste heat. From outer space,
      > their planet may glow like a Christmas tree ornament. Dyson has even
      > proposed looking specifically for infrared emissions (rather than radio
      and
      > TV) to identify these Type II civilizations.
      >
      > Perhaps the only serious threat to a Type II civilization would be a
      nearby
      > supernova explosion, whose sudden eruption could scorch their planet in a
      > withering blast of X-rays, killing all life forms. Thus, perhaps the most
      > interesting civilization is a Type III civilization, for it is truly
      > immortal. They have exhausted the power of a single star, and have reached
      > for other star systems. No natural catastrophe known to science is capable
      > of destroying a Type III civilization.
      >
      > Faced with a neighboring supernova, it would have several alternatives,
      such
      > as altering the evolution of dying red giant star which is about to
      explode,
      > or leaving this particular star system and terraforming a nearby planetary
      > system.
      >
      > However, there are roadblocks to an emerging Type III civilization.
      > Eventually, it bumps up against another iron law of physics, the theory of
      > relativity. Dyson estimates that this may delay the transition to a Type
      III
      > civilization by perhaps millions of years.
      >
      > But even with the light barrier, there are a number of ways of expanding
      at
      > near-light velocities. For example, the ultimate measure of a rockets
      > capability is measured by something called "specific impulse" (defined as
      > the product of the thrust and the duration, measured in units of seconds).
      > Chemical rockets can attain specific impulses of several hundred to
      several
      > thousand seconds. Ion engines can attain specific impulses of tens of
      > thousands of seconds. But to attain near-light speed velocity, one has to
      > achieve specific impulse of about 30 million seconds, which is far beyond
      > our current capability, but not that of a Type III civilization. A variety
      > of propulsion systems would be available for sub-light speed probes (such
      as
      > ram-jet fusion engines, photonic engines, etc.)
      >
      >
      > How to Explore the Galaxy
      >
      > Because distances between stars are so vast, and the number of unsuitable,
      > lifeless solar systems so large, a Type III civilization would be faced
      with
      > the next question: what is the mathematically most efficient way of
      > exploring the hundreds of billions of stars in the galaxy?
      >
      > In science fiction, the search for inhabitable worlds has been
      immortalized
      > on TV by heroic captains boldly commanding a lone star ship, or as the
      > murderous Borg, a Type III civilization which absorbs lower Type II
      > civilization (such as the Federation). However, the most mathematically
      > efficient method to explore space is far less glamorous: to send fleets of
      > "Von Neumann probes" throughout the galaxy (named after John Von Neumann,
      > who established the mathematical laws of self-replicating systems).
      >
      > A Von Neumann probe is a robot designed to reach distant star systems and
      > create factories which will reproduce copies themselves by the thousands.
      A
      > dead moon rather than a planet makes the ideal destination for Von Neumann
      > probes, since they can easily land and take off from these moons, and also
      > because these moons have no erosion. These probes would live off the land,
      > using naturally occurring deposits of iron, nickel, etc. to create the raw
      > ingredients to build a robot factory. They would create thousands of
      copies
      > of themselves, which would then scatter and search for other star systems.
      >
      > Similar to a virus colonizing a body many times its size, eventually there
      > would be a sphere of trillions of Von Neumann probes expanding in all
      > directions, increasing at a fraction of the speed of light. In this
      fashion,
      > even a galaxy 100,000 light years across may be completely analyzed
      within,
      > say, a half million years.
      >
      > If a Von Neumann probe only finds evidence of primitive life (such as an
      > unstable, savage Type 0 civilization) they might simply lie dormant on the
      > moon, silently waiting for the Type 0 civilization to evolve into a stable
      > Type I civilization. After waiting quietly for several millennia, they may
      > be activated when the emerging Type I civilization is advanced enough to
      set
      > up a lunar colony. Physicist Paul Davies of the University of Adelaide has
      > even raised the possibility of a Von Neumann probe resting on our own
      moon,
      > left over from a previous visitation in our system aeons ago.
      >
      > (If this sounds a bit familiar, that's because it was the basis of the
      film,
      > 2001. Originally, Stanley Kubrick began the film with a series of
      scientists
      > explaining how probes like these would be the most efficient method of
      > exploring outer space. Unfortunately, at the last minute, Kubrick cut the
      > opening segment from his film, and these monoliths became almost mystical
      > entities)
      >
      >
      > New Developments
      >
      > Since Kardashev gave the original ranking of civilizations, there have
      been
      > many scientific developments which refine and extend his original
      analysis,
      > such as recent developments in nanotechnology, biotechnology, quantum
      > physics, etc.
      >
      > For example, nanotechnology may facilitate the development of Von Neumann
      > probes. As physicist Richard Feynman observed in his seminal essay,
      "There's
      > Plenty of Room at the Bottom," there is nothing in the laws of physics
      which
      > prevents building armies of molecular-sized machines. At present,
      scientists
      > have already built atomic-sized curiosities, such as an atomic abacus with
      > Buckyballs and an atomic guitar with strings about 100 atoms across.
      >
      > Paul Davies speculates that a space-faring civilization could use
      > nanotechnology to build miniature probes to explore the galaxy, perhaps no
      > bigger than your palm. Davies says, "The tiny probes I'm talking about
      will
      > be so inconspicuous that it's no surprise that we haven't come across one.
      > It's not the sort of thing that you're going to trip over in your back
      yard.
      > So if that is the way technology develops, namely, smaller, faster,
      cheaper
      > and if other civilizations have gone this route, then we could be
      surrounded
      > by surveillance devices."
      >
      > Furthermore, the development of biotechnology has opened entirely new
      > possibilities. These probes may act as life-forms, reproducing their
      genetic
      > information, mutating and evolving at each stage of reproduction to
      enhance
      > their capabilities, and may have artificial intelligence to accelerate
      their
      > search.
      >
      > Also, information theory modifies the original Kardashev analysis. The
      > current SETI project only scans a few frequencies of radio and TV
      emissions
      > sent by a Type 0 civilization, but perhaps not an advanced civilization.
      > Because of the enormous static found in deep space, broadcasting on a
      single
      > frequency presents a serious source of error. Instead of putting all your
      > eggs in one basket, a more efficient system is to break up the message and
      > smear it out over all frequencies (e.g. via Fourier like transform) and
      then
      > reassemble the signal only at the other end. In this way, even if certain
      > frequencies are disrupted by static, enough of the message will survive to
      > accurately reassemble the message via error correction routines. However,
      > any Type 0 civilization listening in on the message on one frequency band
      > would only hear nonsense. In other words, our galaxy could be teeming with
      > messages from various Type II and III civilizations, but our Type 0 radio
      > telescopes would only hear gibberish.
      >
      > Lastly, there is also the possibility that a Type II or Type III
      > civilization might be able to reach the fabled Planck energy with their
      > machines (10^19 billion electron volts). This is energy is a quadrillion
      > times larger than our most powerful atom smasher. This energy, as
      fantastic
      > as it may seem, is (by definition) within the range of a Type II or III
      > civilization.
      >
      > The Planck energy only occurs at the center of black holes and the instant
      > of the Big Bang. But with recent advances in quantum gravity and
      superstring
      > theory, there is renewed interest among physicists about energies so vast
      > that quantum effects rip apart the fabric of space and time. Although it
      is
      > by no means certain that quantum physics allows for stable wormholes, this
      > raises the remote possibility that a sufficiently advanced civilizations
      may
      > be able to move via holes in space, like Alice's Looking Glass. And if
      these
      > civilizations can successfully navigate through stable wormholes, then
      > attaining a specific impulse of a million seconds is no longer a problem.
      > They merely take a short-cut through the galaxy. This would greatly cut
      down
      > the transition between a Type II and Type III civilization.
      >
      > Second, the ability to tear holes in space and time may come in handy one
      > day. Astronomers, analyzing light from distant supernovas, have concluded
      > recently that the universe may be accelerating, rather than slowing down.
      If
      > this is true, there may be an anti-gravity force (perhaps Einstein's
      > cosmological constant) which is counteracting the gravitational attraction
      > of distant galaxies. But this also means that the universe might expand
      > forever in a Big Chill, until temperatures approach near-absolute zero.
      > Several papers have recently laid out what such a dismal universe may look
      > like. It will be a pitiful sight: any civilization which survives will be
      > desperately huddled next to the dying embers of fading neutron stars and
      > black holes. All intelligent life must die when the universe dies.
      >
      > Contemplating the death of the sun, the philosopher Bertrand Russel once
      > wrote perhaps the most depressing paragraph in the English language:
      "...All
      > the labors of the ages, all the devotion, all the inspiration, all the
      > noonday brightness of human genius, are destined to extinction in the vast
      > death of the solar system, and the whole temple of Mans achievement must
      > inevitably be buried beneath the debris of a universe in ruins..."
      >
      > Today, we realize that sufficiently powerful rockets may spare us from the
      > death of our sun 5 billion years from now, when the oceans will boil and
      the
      > mountains will melt. But how do we escape the death of the universe
      itself?
      >
      > Astronomer John Barrows of the University of Sussex writes, "Suppose that
      we
      > extend the classification upwards. Members of these hypothetical
      > civilizations of Type IV, V, VI, ... and so on, would be able to
      manipulate
      > the structures in the universe on larger and larger scales, encompassing
      > groups of galaxies, clusters, and superclusters of galaxies."
      Civilizations
      > beyond Type III may have enough energy to escape our dying universe via
      > holes in space.
      >
      > Lastly, physicist Alan Guth of MIT, one of the originators of the
      > inflationary universe theory, has even computed the energy necessary to
      > create a baby universe in the laboratory (the temperature is 1,000
      trillion
      > degrees, which is within the range of these hypothetical civilizations).
      >
      > Of course, until someone actually makes contact with an advanced
      > civilization, all of this amounts to speculation tempered with the laws of
      > physics, no more than a useful guide in our search for extra-terrestrial
      > intelligence. But one day, many of us will gaze at the encyclopedia
      > containing the coordinates of perhaps hundreds of earth-like planets in
      our
      > sector of the galaxy. Then we will wonder, as Sagan did, what a
      civilization
      > a millions years ahead of ours will look like...
      >
      >
      >
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