RE: Sol-like system discovered...SETI new directions?

From: Paul Grant (shade999@optonline.net)
Date: Mon Jul 14 2003 - 10:17:59 MDT

  • Next message: Kevin Freels: "Re: The End of Hypocrisy? (was: Why Does Self-Discovery Require a Journey?)"

    On Sat, Jul 12, 2003 at 08:26:35PM -0400, ABlainey@aol.com wrote:
    > In a message dated 12/07/2003 11:12:16 GMT Daylight Time,
    > asa@nada.kth.se
    > writes:
    >
    > > For a static field in such a "slow gravity" universe nothing would
    > > change. But imagine sending out Voyager towards Jupiter. At first it

    > > experiences the weak tug towards the place where Jupiter was a long
    > > time ago, and is accelerated that way. As it approaches the region
    > > where Jupiter is, the acceleration will change direction and move
    > > towards the current position, and as Voyager continues beyond it
    > > will shift back towards an old position.
    > >

    Actually it just occurred to me; from a biological pov,
    given how important gravity is to every day use,
    we'ld all be equipped with significantly better gravity
    detectors :) Kind of like "use the force" stuff.

    Amusing.
     
    > I can see that. Wouldn't the gravitational force also be weaker than
    > expected if the voyager past the planet on its sun orbital trailing
    > end ? A kind of gravital doppler shift.

    I think in general we're probably confusing things; as someone more
    versed than I pointed out, gravity can either be static [ignoring
    motion]
    or dynamic (even in our current universe); what you're doing when you
    make
    the propogation speed slower than the speed of light is arbitrarily
    converting all cases of "static" gravity into dynamic cases [at least
    relative to the light data]...

    So, you have a planet which used to be considered static gravity
    [constant
    gravity emittor], which means effectively that at any point in space
    that it occupied it emitted a summative field. When it vacates a
    position, the
    area of space "springs back' to its original configuration + the
    trailing end
    of the planet...[anyone know what the resiliancy of space with respect
    to gravity (SEPerate from the propogation speed of gravity) is btw?]

    Now lets place an observer in front and behind of the planet relative to
    its motion; the observer in front will see in an increase in gravity
    (depending
    on the propogation speed); the frequency shift (doppler effect)
    observed,
    would be a "speed up" of the gravity field changes [the equivalent of
    jerk].
    Suddenly gravity would start increasing, and the rate at which it
    increases
    [remembering that gravity in and of itself is acceleration], would be
    accelerating.
    When he would see this sudden acceleration of gravity (no doubt
    unpleasant),
    would be a ratio of the speed he was going versus the speed of
    propogation.
    This would be the equivalent of the sonic boom.

    The observer in the back of the planet would at some point, see the
    correct vacancy in terms of gravity... but it would take him some time
    to see the vacancy for what it was (a shift in gravitational energies);
    the reason being that the speed of the propogation would determine
    when the final energies (relative to the motion) would be updated.
    He would be seeing the equivalent of a gravitational "flicker";
    2 sources of information (the universe, and this planet), would be vying
    to update his respective environment... with the final result being
    that of the universe winning, with relatively more time in between
    for its frames...

    Now thats with interleaving within a time frame; but try normalizing
    back to a single frame, and what you end up getting is intense
    periods of supergravity in front of the moving gravity "wave"
    and slow update in the trailing field (where you feel the effects
    of gravity where there's no clear source for that gravity, relative
    to how our notion of the universe works)

    > > Even worse, Jupiter is actually moving "supersonically" in this
    > > setting!
    > > If Voyager is approaching from straight ahead of the planet it will
    not
    > > experience any gravitational field since Jupiter is moving faster
    than
    > > the information about where it is is spreading through the gravity
    > > field. So on one side of Jupiter you would actually be weightless!

    <<cut>> on one side you could be *potentially* weightless, until the
    gravity waves reach up and snag you. and then you would probably
    be severely heavy, and if off-axis from the direction of motion,
    probably sheared in half (or quarters or whatever :P).

    > > On
    > > the other side all the information is present and you get normal
    > > gravity. And you get a discontinous bow shock where you go from no
    > > gravity to a mix of several accelerations pointing towards many
    former
    > > positions (likely just causing an inward accleration into the shock
    > > cone).

    perhaps :) I'm considering the simple case of a planet moving
    with observers directly in line with its motion....

    <snip>

    you: Hmm, interesting. An observer on the planet surface would, if
    gravity
    behaved like it does here, observe the same gravity all around the
    surface regardless of where it was moving. An external observer would
    not see the same.

    me:

    it all depends on:
    the speed of propogation,
    the distance from the source,
    the decay of the gravitational attraction per meter,
    the resiliancy of space (refraction period similar to a neuron),
    and of course, the vector of motion relative to the observer's position.

    if you really want to have some fun, consider the planet not as a point
    source, but as a series of point sources...then look at it from the
    observers point of view....(six gagillion gravitional shockwaves
    all happening simoultaneously underneath said person).

    I daresay given the eddy currents involved in front, you would never
    really get a planet in the first place; at least not one that's stable.

    you:
    My model is based on having gravity disturbances move
    relative to a fixed spacetime *at a constant speed relative to this
    frame*.
    There cannot be a fast or slow gravity wave in my model, all gravity
    waves
    move at the speed g. Just like light in relativity and sound in still
    air. If we allow gravity waves of different speeds then things get
    *really* messy and interesting. I guess a fast moving planet would have
    a field that moved fast to a receiver, while a slowly moving planet
    would have a slowly expanding field. I think we need extra assumptions
    here, and the whole thing starts to look like the theory of nonlinear
    waves. Very interesting, but confusing.

    omard-out



    This archive was generated by hypermail 2.1.5 : Mon Jul 14 2003 - 10:26:51 MDT