November 17, 2006

Dark Energy

From The New York Times - astronomers pursue dark matter, all the way back to nine billion years ago:

The data suggest that in fact, dark energy has changed little, if at all, over the course of cosmic history. Though hardly conclusive, that finding lends more support to what has become the conventional theory, that the source of cosmic antigravity is the cosmological constant, a sort of fudge factor that Einstein inserted into his cosmological equations in 1917 to represent a cosmic repulsion embedded in space.

Although Einstein later abandoned the cosmological constant, calling it a blunder, it would not go away. It is the one theorized form of dark energy that does not change with time.

Einstein invented his constant to explain why the universe does not collapse. After he abandoned it, the theory was resuscitated by quantum mechanics, which showed that empty space should be bubbling with staggering amounts of repulsive energy. The possibility that it really exists in the tiny amounts measured by the astronomers has flummoxed physicists and string theorists.

Because it is a property of empty space, the overall force of Einstein’s constant grows in proportion as the universe expands, until it overwhelms everything.

So far, he said, the results are consistent with the cosmological constant, but other answers are also possible. The possibility that it is the cosmological constant is a mixed blessing. Physicists concede that they do not understand it.

Dr. Carroll of Caltech said, “Dark energy makes us nervous.”

Hmmm, me too, now that you mention it. Thanks for that guys.

[Hell, didn't we have enough to worry about with the obesity crisis? - ed]

7 comments:

  1. "A new camera could extend observations to 11 billion or 12 billion years back."

    I say lets call the whole thing off.

    Look to the future not the past!

    Imagine the millions of dollars that could be channelled into much more altruist ventures that would benefit peoples lives.

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  2. Ah, you're a brave woman Kath.

    Not concerned about the universe collapsing.

    Not concerned about dark matter moving in and taking over the universe.

    But, yeah, okay, you're right.

    Let's leave it for the great-great-great
    great-great-great-great-great-great
    great-great-great-great-great-great
    great-great-great-great-great-great
    great-great-great-great-great-great
    great-great-great-great-great-great
    great-great-great-great-great-great
    great-great-great-great-great-great
    great-great-great-great-great-great
    great-great-great-great-great-great
    grandchildren to worry about. Besides, we have to leave them a few exciting things to do.

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  3. Kathy8:24 AM

    psssst... Hey Caz!
    Harry's Back....

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  4. Maybe they should drop the name 'Cold Dark Matter'. It's a very depressing sort of nomenclature. Earth itself is classified as 'Cold Dark Matter', and that's only true some of the time, after all.

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  5. Let's call it "Happy Huggie Matter"!

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  6. I'm not sure that we should indulge Timmy's need to feel that the universe revolves around his whimsies Drunka.

    Well, we could, but we won't.

    "Happy Huggie Matter" - that already exists, here on earth, doesn't it? "Warm Huggie Matter", in fact, which may also be happy matter, depending on how you look at it, in the form of babies disposable nappies.

    See Tim, dark matter - the stuff out there - is always dark matter - it has singularly distinguished itself as deserving of the nomenclature! What, you want a perky name for dark matter!?

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  7. Pentcho Valev7:38 PM

    THE STRANGEST DILEMMA IN PHYSICS

    Cosmological concepts like dark energy etc. are all based on frequency shift data and therefore the equations

    c = Lf ; c' = L'f'

    where c is speed of light, L is wavelength and f is frequency, are crucial. If c'=c=300000km/s we have

    c = L'f' /1/

    If the speed of light is variable and, as Einstein showed in 1911, obeys the equation c'=c(1+V/c^2), where V is the gravitational potential, /1/ is wrong and we have, instead,

    L' = L ; c' = Lf' /2/

    Clearly /1/ and /2/ are incompatible and here the strangeness begins. Physicists usually assume that /1/ is true but rarely say /2/ is wrong. Sometimes they give praise to Einstein's 1911 equation c'=c(1+V/c^2) and therefore implicitly assume that /2/ is true and /1/ is wrong. Yet physicists would never openly discuss the implications of /2/: they suspect that this particular discussion has something to do with a prophecy of Einstein's:

    "If the speed of light is the least bit affected by the speed of the light source, then my whole theory of relativity and theory of gravity is false."

    Pentcho Valev
    pvalev@yahoo.com

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