Re: OT: One More Time ... Prof. Alan Guth at Stanford Monday Night

From: Christopher Hays (hays-sf@No-Spam)
Date: Wed Jan 29 2003 - 12:07:22 MST

  • Next message: Mark Wagner: "Re: ATM question..."

    Hammerstein lifted it from Shakespeare:

    "Nothing will come of nothing."

    [Shakespeare, "King Lear," Act 1, Scene 1 (1608)]

    Christopher

    Jane E. Smith wrote:

    >Bob,
    >
    >Wonderful sysnopsis! Thanks for taking the time to rewrite it.
    >
    >Looks like they were wrong afterall:
    >
    > "Nothing comes from nothing, nothing ever could..."
    >
    > Rodgers and Hammerstein, 1965
    > "Sound of Music"
    >
    >Jane Smith
    >
    >
    >
    >At 12:13 AM 1/29/2003 -0800, you wrote:
    >
    >
    >>Monday night's lecture was a fun one, with Dr. Alan Guth (MIT) speaking
    >>on "Cosmic Inflation and the Accelerating Universe." For those of you
    >>not aware of just who he is, Prof. Guth is the father of inflation
    >>theory, which currently provides the best explanation for the
    >>development and state of our universe. There were a number of TAC'os
    >>attending the lecture, and I sat with a few of the PAS folk, to include
    >>Ken Lum, Bud Wittlin and Alan Adler. The lecture was designed for the
    >>physics layperson, i.e., no math! Well, virtually none.
    >>
    >>To highlight the *initial* part of Monday's lecture (inflation), Prof.
    >>Guth first described what lead to the development of his inflation
    >>theory: Big Bang issues associated with "omega" and a "flat" universe.
    >>The universe now appears to be extremely flat, meaning that the mass,
    >>gravity and velocity properties of the universe are balanced between an
    >>open and a closed universe. Omega describes the ratio between the
    >>density of matter in the universe and the theoretical density needed to
    >>make the universe perfectly flat. If omega is greater than 1, we end up
    >>with a closed universe and a Big Crunch coming. If omega is less than
    >>one, then we have an open universe that goes on expanding forever. In a
    >>flat universe - just in case you wondered - the universe continues to
    >>expand without limit, but with the rate of expansion getting closer and
    >>closer to zero as time goes on. Anyway, for the universe to be as flat
    >>as it currently is, Prof. Guth stated the value of omega just one-second
    >>after the Big Bang would have had to be 1 ... to an accuracy of 15
    >>decimal places, an extremely "finely tuned" number, as he described it.
    >>Well, this is what got Prof. Guth thinking and moving ... with his
    >>inflation theory eventually resolving the problem. With inflation, the
    >>universe didn't need to be fine-tuned from the beginning, but would
    >>instead "drive" omega toward 1 all by itself, resulting in a flat
    >>universe. By the way, Prof. Guth reminded everyone that Big Bang
    >>"theory" just describes the aftermath of the Big Bang, but not what the
    >>Big Bang was or how it developed ... or why the universe appears to be
    >>so "uniform." Inflation, however, addresses all of this.
    >>
    >>To start, Prof. Guth noted that Quantum theory holds that a vacuum is
    >>subject to quantum uncertainties, so particles materialize into and
    >>vanish out of vacuums ... albeit very quickly. At extremely high energy
    >>levels, theories predict that a form of matter can be created that is
    >>gravitationally repulsive rather than attractive. This matter, which
    >>would have erupted from the primordial vacuum, is called a false vacuum.
    >>When an incredibly small "patch" of this matter formed, no larger than a
    >>billionth of the size of a proton, the false vacuum's unimaginably
    >>strong repulsive gravitational field would have expanded explosively.
    >>The expansion would be exponential, with the region's diameter doubling
    >>every 10^-37 seconds. After a hundred of these doublings - Prof. Guth
    >>said there might have even been more - the "billionth-of-a-proton" sized
    >>region would have grown to the size of a marble. For comparison
    >>purposes, this increase is equivalent to a pea growing to the size of
    >>the Milky Way ... in a tiny fraction of a second! As the region
    >>expanded, its density also remained constant, no "thinning out" at all,
    >>so the total amount of mass in the region increased by an unbelievable
    >>amount. Although the increase in mass seems like a violation of energy
    >>conservation, a "loophole" - the energy of a gravity field itself is
    >>negative, which cancels the positive energy of the matter - keeps the
    >>total energy constant. The expansion of the region also seems to
    >>violate "Einstein's cosmic speed limit," but Prof. Guth noted that even
    >>though the region grew at faster-than-light speed, "no particle within
    >>the region would ever win a race with a beam of light." Inflation ends
    >>because the false vacuum is fundamentally unstable, and decays like
    >>radioactive material - in exponential fashion - characterized by a
    >>half-life. The material decays into ordinary gravitational-attractive
    >>material, where the particles scatter off each other, quickly reaching
    >>thermal equilibrium, which creates that "primordial soup" we all
    >>associated with the Big Bang.
    >>
    >>So it looks like the universe was created by a random quantum
    >>fluctuation out of nothing. The item I found most interesting was the
    >>notion that if you add up all the matter (positive) and gravity
    >>(negative) in the universe, they appear to precisely balance one another
    >>... or cancel each other out, as it were. As Prof. Guth described it,
    >>matter plus gravity equals zero. So the universe can be created from
    >>nothing ... because the universe *IS* nothing!
    >>
    >>Okay, so for those of you who were there, e.g., David Kingsley, Jeff
    >>Crilly and James Turley - or those of you already in the know, e.g.,
    >>Leonard, Da Weasel and ZZ - did I get this stuff from Prof. Guth
    >>correct? <grin> If not, speak up!
    >>
    >>Obviously there was a lot more to all this - the second half of the
    >>lecture went into acceleration, which fits in perfectly with inflation -
    >>but at least this gives you the flavor of it all. Prof. Guth was also
    >>very approachable, and after the lecture I asked him a couple of
    >>questions about the polarization of the cosmic microwave background,
    >>which he answered and expanded upon. Stanford's own Andrei Linde, an
    >>incredible cosmologist in his own right, finally came over to rescue
    >>Prof. Guth from people like me. <grin> Linde pointed out that both he
    >>and Prof. Guth theorized that the decay of the false vacuum did not
    >>happen all at once either. They both believe that while some regions
    >>decay into universes, other regions keep expanding and creating other
    >>universes. And if that weren't enough, they also believe that
    >>"residual" false vacuum from the creation of all these universes creates
    >>still more of 'em. As noted by Linde - and I was writing this down as
    >>fast as I could, so I hope I have it right - he described this as "the
    >>eternally existing self-reproducing inflationary universe." Pretty
    >>cool, huh!
    >>
    >>Anyway, a great time had by all.
    >>
    >>(If you missed the lecture, and still want to see it, have James Turley
    >>construct a Gott Time Machine for you ... uh, one that won't collapse on
    >>itself. <grin>)
    >>
    >>...Bob...
    >>Bob Czerwinski
    >>
    >>
    >>
    >>
    >
    >
    >



    The Astronomy Connection -- Mailing List Archives