Is this really true or it's just science fiction?

This is a discussion on Is this really true or it's just science fiction? within the A Brief History of Cprogramming.com forums, part of the Community Boards category; "Is "therefore our understanding of the situation is woefully inadequate" also not a viable conclusion - seems reasonable to me. ...

  1. #136
    The Earth is not flat. Clyde's Avatar
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    "Is "therefore our understanding of the situation is woefully inadequate" also not a viable conclusion - seems reasonable to me. "

    ..... Relativity predicted plenty of phenomenon before we had the means to test them: time dilation being one. We have predicted extra matter in the universe based on very simple observations, and whilst we currently cannot detect it, hopefully we will be able to in the near future.

    Having said that, its not unfeasable that there is an alternative explanation of why the universe is not expanding at its expected rate.

    Just because we don't know everything doesn't mean our understanding is "woefully inadequate".

    "Agree with that, I've been advocating an open minded position throughout the debate. "

    I am in full support of replaceing a theory with a better one, i just don't think the main body of relativity will ever be changed.

    "Naturally. The same can be said of anyone. People are either so expert in a field that they lose sight of the bigger picture, of have a broad enough overview to see the problems but not the details. "

    That is false, people who are professors of physics, know exactly the strengths and weakness's of the theories in their subject, they are the only ones who are in a position to evaluate them. There is no "bigger picture" that cosmologists are missing.

    "I would suggest that you think that's what they would produce, because that is what you think. I am prepared to accept that they may, or possibly a completely different self consistent model might emerge. "

    The above argument could be applied to the Earth's geometry, take a bunch of mathematically orientated people, don't tell them anything about the shape of the Earth. Then ask the to come up the Earth's geometry... I'd say they'd conclude the exact same thing we conclude now: The Earth is round.

    Now, if we don't consider what the problem actually is, then we could quite easily conclude that they might conclude something different

    I realise i'm not going to convince you, because i lack the knowledge to do so. If you cover relativity in DETAIL, you will convince yourself.

    "So we have two objects, stationary with respect to the space they occupy, but in two parts of space that are travelling above c relative to each other... "

    No we don't, because spacio-temporal geometry is not linear, the reason they aren't travelling faster than light relative to each other is because of time dilation.

    "I am not going to lose my doubts while there are so many fiddle factors added to make things look right"

    But there ARENT, I hear the same argument about evolution by people who don't know the theory well enough, they think there are all these problems that actually have already been solved by specialists in the field (i do better in evolution arguments because i know more about it).

    "I was at a seminar a year back where two groups were presenting their work and arguing for a ressurrection of the "cosmological constant". Fun thing was, their estimates of it's value had opposite signs!"

    Yup, the cosomological constant is making a comeback.

    "I'm not going to lose my doubts, and I suspect you are not going to accept them!"

    Guess only time will tell eh.
    Last edited by Clyde; 04-09-2002 at 08:30 AM.

  2. #137
    It's full of stars adrianxw's Avatar
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    In common experience, most people talk about gravity and electro/mag only. The two nuclear forces are a little esoteric.

    I suspect Clyde is refering to "4" to avoid potential confusion that may arise if he'd said something else. It would be unwise to assume that the average reader of a general forum like this would necessarily be aware of the reduction that occurs at higher energies.
    Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.

  3. #138
    The Earth is not flat. Clyde's Avatar
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    "Hasn't it now been reduced to just two? At least that is what I remember Stephen Hawking saying in "A Brief History of Time"."

    Really? Last i heard it was still gravitational, electro-magnetic, nuclear strong and nuclear weak.

    *Goes to check his copy of Brief history of Time*

  4. #139
    It's full of stars adrianxw's Avatar
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    >>> i just don't think the main body of relativity will ever be changed.

    I guessed!

    >>> But there ARENT,

    >>> Yup, the cosomological constant is making a comeback.



    >>> Guess only time will tell eh.

    Reckon so.
    Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.

  5. #140
    Funniest man in this seat minesweeper's Avatar
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    I just seem to remember him referring to two fundamental forces, it may have been in a different context though so i could be wrong.

    I seem to remember him possibly saying something about how it is possible to unify them all except gravity which couldn't be included/explained as it was only ever attractive and never repulsive. Though I'm not sure whether Nuclear strong is ever repulsive, you would know more than me, in which case maybe it was gravity and nuclear strong as one force and nuclear weak and elec/mag as the other.

  6. #141
    The Earth is not flat. Clyde's Avatar
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    ">>> But there ARENT,

    >>> Yup, the cosomological constant is making a comeback. "

    The cosomological constant doesn't really contradict relativity. It is merely represents another factor.

    "I seem to remember him possibly saying something about how it is possible to unify them all except gravity which couldn't be included/explained as it was only ever attractive and never repulsive"

    Ah well, gravity represents a substantial problem, because it seems to be completely different to the other three forces. String theory and other attempts at a GUT have had some success in unifying the three other forces.... but in each case the model has failed because gravity screwed it up.

    I'm fairly sure that the four forces are still considered separate, simply because in my lectures we still refer to them separately.

  7. #142
    Funniest man in this seat minesweeper's Avatar
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    Quite possibly, it may well have been a particular context that he was discussing at the time where it is valid to consider the other three forces as one or alike but of course as he says numerous time in the book, gravity is a special case which so far has greatly prohibited the production of a GUT.

  8. #143
    It's full of stars adrianxw's Avatar
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    >>>
    The cosomological constant doesn't really contradict relativity. It is merely represents another factor.
    <<<

    In the context of my previous message, I was simply suggesting the the cosmological constant is an example of a fiddle factor.

    >>>
    I'm fairly sure that the four forces are still considered separate, simply because in my lectures we still refer to them separately.
    <<<

    I don't think any serious researchers, (or damned insolent amateurs), would regard the unification of electro/mag and weak as doubtful. The prediction of the W+, W- and Z0 and the subsequent isolation of those particles by Rubia and Meer seems to bear it out.

    GUT is still out there. TOE is a pipe dream at this time.
    Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.

  9. #144
    The Earth is not flat. Clyde's Avatar
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    "I don't think any serious researchers, (or damned insolent amateurs), would regard the unification of electro/mag and weak as doubtful. The prediction of the W+, W- and Z0 and the subsequent isolation of those particles by Rubia and Meer seems to bear it out"

    I see, thanks for the correction.

  10. #145
    Ethereal Raccoon Procyon's Avatar
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    A couple misconceptions I'd like to clear up:


    Originally posted by Clyde (I think; it's been ambiguously quoted too many times to be sure)

    Dark matter is simple; can measure how fast the universe is expanding, and basically we can tell that the rate that its slowing down is much more than it should be given the observeable mass of the universe. Hence the conjecture that there is extra mass out there that we can't see accounting for the extra slow down: dark matter.
    This is not correct, you are mixing up two theories. Dark matter is postulated based on at least four primary lines of evidence: the rotation of spiral galaxies, the rotation of galaxy clusters, computer simulations of the condensation of supercluters from the early universe, and the properties of the cosmic microwave background radiation. It does a very good job of describing all of these phenomena, despite its seemingly ad-hoc nature. It has not yet been actually physically observed.

    What you are probably thinking of is the evidence used to justify the existence of the cosmological constant (which you also mentioned). Recent observations of supernovae suggest that the rate of expansion of the universe is speeding up, when gravitation due to matter in the universe should be causing it to slow down. So, Einstein's anti-gravity cosmological constant, and other forms of vacuum energy, have been proposed to explain this new result, which is probably the biggest discovery in cosmology - maybe even in all of astronomy - in decades.

    BTW, how do physicists feel about the faster than light problems associated with cosmologists inflation theory
    The fact that the expansion (inflation) of the early universe was throught to occur at "speeds" exceeding that of light does not refute relativity. Nothing is actually moving during this expansion; the geometry of spacetime is simply changing in such a way that objects are brought out of causal contact. Cosmic expansion has the same effect on the Doppler shift and many other properties as recessive velocity, but it's not really the same phenomenon.

  11. #146
    The Earth is not flat. Clyde's Avatar
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    You're right, i was confusing the two, thanks setting me straight.
    (I should stick to chemistry=))

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