Re: An explanation for the increasing expansion

From: brodix (brodix_at_earthlink.net)
Date: 09/10/04

  • Next message: Cecil Moore: "Re: Aether is the empty space in which the Universe sits" 
    Date: 9 Sep 2004 20:33:43 -0700

    TomGee,
    > >
    > How does gravity cause space to collapse, and just what do you mean by
    > "collapse"?

     Einstein proposed the cosmological constant because according to his
    calculations, gravity would cause the entire universe to collapse to a
    point. A good example of this theory are black holes and the extent to
    which they effectively collapse three dimensional space.

      And what and how "is shedding...radiation."?

     Light, basically. As gravity contracts matter, it radiates the
    constituant energy..starlight.
    > >
    > When does space curve the other way? According to Einstein, massive
    > objects curve space as they move through it. Ostensibly, space
    > reverts to its original location after the mass passes. How would
    > radiation cause it to return to being "straight" instead of curved
    > after the object has passed?

     There is no straight space. There is expanding space and collapsing
    space. just like zero is not a number, but the state between positive
    and negative numbers. These two balance out so that the average is
    effectively flat.In the two dimensional description of gravity, mass
    depresses the ***. Where there is no mass, the *** isn't flat, but
    curves upward. As the actual distribution of mass is very dispersed,
    this is not a pronounced effect.

    > I must sign in and give too much information for me to join that site.

    Cosmology
    Things fall apart
    Feb 5th 2004
    >From The Economist print edition
    What if the dark energy and dark matter essential to modern
    explanations of the universe don't really exist?

    IT WAS beautiful, complex and wrong. In 150AD, Ptolemy of Alexandria
    published his theory of epicycles—the idea that the moon, the sun and
    the planets moved in circles which were moving in circles which were
    moving in circles around the Earth. This theory explained the motion
    of celestial objects to an astonishing degree of precision. It was,
    however, what computer programmers call a kludge: a dirty, inelegant
    solution. Some 1,500 years later, Johannes Kepler, a German
    astronomer, replaced the whole complex edifice with three simple laws.

    Some people think modern astronomy is based on a kludge similar to
    Ptolemy's. At the moment, the received wisdom is that the obvious
    stuff in the universe—stars, planets, gas clouds and so on—is actually
    only 4% of its total content. About another quarter is so-called cold,
    dark matter, which is made of different particles from the familiar
    sort of matter, and can interact with the latter only via gravity. The
    remaining 70% is even stranger. It is known as dark energy, and acts
    to push the universe apart. However, the existence of cold, dark
    matter and dark energy has to be inferred from their effects on the
    visible, familiar stuff. If something else is actually causing those
    effects, the whole theoretical edifice would come crashing down.

    Space

    Tom Shanks' paper is published in Monthly Notices of the Royal
    Astronomical Society. His research is based on data gathered from
    NASA's WMAP satellite. Sebastien Vauclair (in French) and colleagues
    published their findings in Astronomy and Astrophysics.

    According to a paper just published in the Monthly Notices of the
    Royal Astronomical Society by Tom Shanks and his colleagues at the
    University of Durham, in England, that might be about to happen. Many
    of the inferences about dark matter and dark energy come from detailed
    observations of the cosmic microwave background (CMB). This is
    radiation that pervades space, and is the earliest remnant of the Big
    Bang which is thought to have started it all. Small irregularities in
    the CMB have been used to deduce what the early universe looked like,
    and thus how much cold, dark matter and dark energy there is around.

    Dr Shanks thinks these irregularities may have been misinterpreted. He
    and his colleagues have been analysing data on the CMB that were
    collected by WMAP, a satellite launched in 2001 by NASA, America's
    space agency. They have compared these data with those from telescopic
    surveys of galaxy clusters, and have found correlations between the
    two which, they say, indicate that the clusters are adding to the
    energy of the CMB by a process called inverse Compton scattering, in
    which hot gas boosts the energy of the microwaves. That, they say,
    might be enough to explain the irregularities without resorting to
    ghostly dark matter and energy.

    Dr Shanks is not the only person questioning the status quo. In a pair
    of papers published in a December issue of Astronomy and Astrophysics,
    Sebastien Vauclair of the Astrophysics Laboratory of the
    Midi-Pyrénées, in Toulouse, and his colleagues also report the use of
    galaxy clusters to question the existence of dark energy. But their
    method uses the clusters in a completely different way from Dr Shanks,
    and thus opens a second flank against the conventional wisdom.

    Cosmological theory says that the relationship between the mass of a
    galaxy cluster and its age is a test of the value of the "density
    parameter" of the universe. The density parameter is, in turn, a
    measure of just how much normal matter, dark matter and dark energy
    there is. But because the mass of a cluster is difficult to measure
    directly, astronomers have to infer it from computer models which tell
    them how the temperature of the gas in a cluster depends on that
    cluster's mass.

    Even measuring the temperature of a cluster is difficult, though. What
    is easy to measure is its luminosity. And that should be enough, since
    luminosity and temperature are related. All you need to know are the
    details of the relationship, and by measuring luminosity you can
    backtrack to temperature and then to mass.

    That has been done for nearby clusters, but not for distant ones
    which, because of the time light has taken to travel from them to
    Earth, provide a snapshot of earlier times. So Dr Vauclair and his
    colleagues used XMM-Newton, a European X-ray-observation satellite
    that was launched in 1999, to measure the X-ray luminosities and the
    temperatures of eight distant clusters of galaxies. They then compared
    the results with those from closer (and therefore apparently older)
    clusters.

    The upshot was that the relationship between mass and age did not
    match the predictions of conventional theory. It did, however, match
    an alternative model with a much higher density of "ordinary" matter
    in it.

    That does not mean conventional theory is yet dead. The Newton
    observations are at the limits of accuracy, so a mistake could have
    crept in. Or it could be that astronomers have misunderstood how
    galaxy clusters evolve. Changing that understanding would be
    uncomfortable, but not nearly as uncomfortable as throwing out cold,
    dark matter and dark energy.

    On the other hand, a universe that requires three completely different
    sorts of stuff to explain its essence does have a whiff of epicycles
    about it. As Albert Einstein supposedly said, "Physics should be made
    as simple as possible, but not simpler." Put Dr Shanks's and Dr
    Vauclair's observations together, and one cannot help but wonder
    whether Ptolemy might soon have some company in the annals of
    convoluted, discarded theories.
    > >
    > Are you saying that the expansion of the universe creates additional
    > gravitation which impacts galaxies? If so, how?

     No! The universe doesn't expand, but space does. The result is
    pressure on gravitational systems.

    > >
    > So you think hydrogen and other elements condense out from space?

     Not "space". The radiation pervading it. As starlight is constantly
    adding to it and it is only stable to a very low level, just as the
    atmosphere can only hold so much moisture before raindrops form.
    > >
    > > > > C is the speed of light in a vacuum. As light passes through these
    > > > > fields,
    > >
    > What fields?
    > >
     The gravity fields of intermediate galaxies and other distributions
    of matter throughout space.

    > > > > it would be slowed somewhat, causing the waves to become
    > > > > shorter, thus blueshifted. For this effect to be reversed, the light
    > > > > would have to exceed C to reverse this slowing.
    > > > >
    > Do you mean for it to be reversed after the light passes the gravity
    > fields?
    > >
    The argument has been that any effect of the light entering the
    gravity field is reversed as it leaves the field.
    > >
    > Why wouldn't it be dark energy?

    Because the assumption has been that only the initial force of the
    singularity is what causes the expansion. It was assumed it should be
    slowing down. Instead it is apparently speeding up. As my point has
    been that the expansion is a factor of light, then it should be a
    constant. So I don't need to explain where it comes from, ie. I don't
    need the dark energy. I just need to explain why light from closer
    sources has a greater average redshift the light that has been
    traveling further.
    > >
    > Are you saying that space remains curved after a massive body passes
    > through it?

     This is actually a much more involved discussion as to the nature of
    what space is. ...But what i was saying is that light waves that have
    been blueshifted passing through gravity fields do not have the
    effect cancelled, ie. the effect of falling into these gravity wells
    isn't reversed by climbing back out of them.

    regards,

    brodix

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