Gravity never zero

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Ivan, Dec 18, 2011.

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  1. AlexG Like nailing Jello to a tree Valued Senior Member

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    This is often heard from those who don't know and believe that therefore no one does.
     
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  3. OnlyMe Valued Senior Member

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    The first part I understand, and it requires no comment. The part in red I completely fail to understand what if anything you were trying to say. Maybe I am just tired...

    As far as the statement you were responding to... Whether you are talking particle physics or cosmology and astronomy, we discover new things all the time that require us to rethink what we thought just last year. It should not be hard to accept that how we understand things to be, does change with time and new discoveries.
     
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  5. Robittybob1 Banned Banned

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    As I understand it now the Uncertainty Principle relies on a formula that tends to a minimum. If there was a time it was ever was brought to the minimum, both the momentum and the position of a particle would have been defined with the maximum possible precision.
     
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  7. origin Trump is the best argument against a democracy. Valued Senior Member

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    Huh?
     
  8. Robittybob1 Banned Banned

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    From Wikipedia on WUP;
    To have it a the minimum limit "one half of the reduced Planck constant ħ" the "particle would have been defined with the maximum possible precision".

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  9. OnlyMe Valued Senior Member

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    This is the theoretical definition, of the limits. There is no question that the underlying theory is one of our most successful predictive theories. Keeping that in mind outside of the mathematical model, we do not currently have technology capable of measurements on the predicted scale — Planck lengths.

    I have not been trying to say that the theory is wrong. What I continue to try and point out is that, some of how we "see" the world is an artifact of the quantifiable nature of our senses and measuring devices. All of which fall far short of the mathematically predicted scale(s) involved.

    While the uncertainty principle and Planck scale limits are logical conclusions, they remain beyond our current ability to confirm with certainty. We can conduct no experiment that can separate the process of measurement and observation from the uncertainty...
     
  10. Syne Sine qua non Valued Senior Member

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    That's a philosophical opinion, not a scientifically valid fact.
     
  11. OnlyMe Valued Senior Member

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    How do you measure 1 Planck length?

    And yes, this is a philosophical point. But the theory cannot be distinguished from philosophy at those scales. You may wish to call it scientific theory, but without the means to actually measure — the theory becomes no more than the basis of philosophical conclusions, logically derived from a mathematical model that defines the world at a scale that cannot be measured.

    It is really only since theoretical physics has become almost indistinguishable from the mathematical models it relies on, that its philosophical roots have been shunned. There is nothing wrong with this as long as the limits of those models are not lost.

    Back to the uncertainty principle, WiKi becomes confused on questions like this, largely as a result of the fact that the question is answered by people who do not all share the same frame of reference. The answer you get depends on who you ask. The reason this can stand is that no one knows with certainty, what the one and only answer is. At least within the context of current technology.

    As far as I know there is no scientifically proven fact available on this issue. Again, the answer lies in experiments in which we cannot separate the uncertainty of measurement and observation, from the conclusions Until we can, we cannot know with certainty where the uncertainty originates.
     
  12. Syne Sine qua non Valued Senior Member

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    Who are you talking to here? What does the Plank length have to do with ANYTHING I said? Are you just doing some leg work for a future straw man?

    There's a consensus based solely on the actual physical consequences, with no room for philosophical doubts.
     
  13. Robittybob1 Banned Banned

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    Define a "straw man" please?

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  14. OnlyMe Valued Senior Member

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    The referrenced to the Planck length was directed at Robittbob's Wiki reference on the issue.

    In your own post your last quote referrs to the act of measurement affecting the certainty or uncertainty. Yes, the theory says this is a fundamental aspect of wave particle duality, but that cannot be experimentally confirmed unless the uncertainty introduced by the act of measurement can be eliminated.

    Consensus only establishes what is currently accepted. It does not establish any conclusion as fact. Consensus shifts with experimental discovery, confirmation and/or and verification.

    This really is nothing that deserves debate. How the subject is viewed and answered is largely an artifact of from where one approaches the question.
     
  15. OnlyMe Valued Senior Member

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    He was implying that I was misrepresenting his position. I just did not separate your post from the general discussion.
     
  16. OnlyMe Valued Senior Member

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    By the way hyperphysics FAQ links are not always the best source of up to date information, though they do provide a good calculator source for a number of issues. The last calculator in this Hyperphysics link is a calculator for "Relativistic mass", which is misleading and and would not meet the test of general scientific consensus. It is an old and outdated concept.
     
  17. Robittybob1 Banned Banned

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    That equation I quoted was using the term (1/2) Reduced Planck's Constant. (Reduced Planck's Constant is from Planck's Constant/2*Pi().
    Plank's constant is not a Planck Length.

    Reduced Planck constant ħ = h/2π
    where h is Planck constant = 1.054571726(47)×10−34 J s
    So it does seem numerically like a small amount

    And the minimum Uncertainty is half of that again.
     
  18. OnlyMe Valued Senior Member

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    Your WiKi quote was,

    As soon as you equate the reduced Planck's constant with position and momentum or another aspect of a particle it becomes a unit of measure. Be that time, length.., etc.

    I just generalized that to length. The point is that whatever measurement is involved it lies in the realm of theory and well beyond our current technology to experimentally measure and confirm.

    And again I am not suggesting the theory is wrong. My only purpose was to emphasize the fact that there is a difference between that portion of our theories which have been experimentally confirmed and those which have not.
     
  19. Syne Sine qua non Valued Senior Member

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    The measurement doesn't affect the uncertainty relation at all. The attempt to simultaneously measure two such related properties merely demonstrates the physical fact. The measurement has no affect one whether or not there is an uncertainty relation, as that relation is only uncertain under SIMULTANEOUS MEASUREMENT.

    So it can't be confirmed unless it is disproven? Nonsense.

    No, you simply don't understand the physical evidence, i.e. facts.

    BTW:

    I never said anything about the Plank constant. You and OnlyMe really need to keep track of who you're talking to.
     
  20. Robittybob1 Banned Banned

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    @Syne - If you never mentioned the Planck's Constant, it is obvious who my comments were directed to.
    Now do you agree that if you measured both the position and momentum of the particle the best you could do would be to have the uncertainty down to the minimum ħ/2?

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  21. hansda Valued Senior Member

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    I think Uncertainty is a phenomena which depends upon the observer or the observation rather than the object .

    For example take the case of a coin . When the coin is tossed , the coin will follow its own mechanics and dynamics and fall on either head or tail . If this mechanics or dynamics of coin is known , it can be predicted well whether the coin will fall head or tail .


    Alternately without applying the dynamics of coin , an observer can predict qualitatively applying the uncertainty principle , whether the coin will fall head or tail .
     
  22. OnlyMe Valued Senior Member

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    It would seem that your objection emphasizes my point, that the uncertainty is due to the measurement. We cannot measure one thing without affecting or even losing the ability to measure the other.

    I don't think you really understand what I was saying. I have no idea just what you are referring to being disproven.

    It cannot be argued that there is no uncertainty in the act of measurement, at the scales involved. It cannot even be augured that when we make any measurement, other aspects of a particle's character are changed or even become unmeasurable. Part of that may be due to the limitation that we cannot simultaneously measure multiple aspects of the particle..., like location and momentum.., but at least a portion is also due to the inherent uncertainty in the measurement itself.

    Unless I completely misunderstanding what you are talking about, you make no sense in the above response. Everything, in high energy particle physics, winds up being a matter of interpretation based on the theoretical model, within which the data is interpreted. Most of the information we have is from particle accelerators and the collection of a great deal of information from many many particle interactions. There are very few situations where individual particles are measured.

    Consensus of opinion is just that a consensus of opinion. An agreement by a majority. Even then it must be kept in mind that what is being agreed upon is how something should be interpreted.., a majority opinion. Once something is proven, it no longer requires a consensus view.

    The link above demonstrates only that there remains some debate on the issue. It does not represent the consensus view. The subject has been discussed several times before on these forums and is not worth another long debate here. Your above link cited three references two are not readily available online without subscription. However, a search on those titles turns up the following rebuttal.

    A quote from, On the Abuse and Use of Relativistic Mass,
    Having found that a consistent theory of special relativity that is based upon proper relativistic quantities and relativistic mass can not be formulated, one is left to wonder why it is still considered with such passion. If it can not be considered as a primary concept of the theory, all that is left is to consider it as a heuristic. This is troublesome for it introduces a view that is at odds with the formal theory.

    Keep in mind that while there are certainly individual discussions and/or debates within any thread, there is also the general thread discussion. My posts here have been directed toward that general discussion.
     
  23. Syne Sine qua non Valued Senior Member

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    The uncertainty is not caused by the measurement, it is caused by the physical facts of how each property must be measured.

    ...To measure space coordinates and instants of time, rigid measuring rods and clocks are required. On the other hand, to measure momenta and energies, devices are necessary with movable parts to absorb the impact of the test object and to indicate the size of its momentum. Paying regard to the fact that quantum mechanics is competent for dealing with the interaction of object and apparatus, it is seen that no arrangement is possible that will fulfill both requirements simultaneously... -Max Born​

    You said that the uncertainty principle couldn't be confirmed unless it could be eliminated. That is just ridiculous on the face of it, as you cannot confirm a thing by doing away with it.

    "Unmeasurable"? How is it "unmeasurable"? Are you saying that somehow otherwise reliable measuring devices magically become unable to give a reading? Or is it much more logical to say that they continue to operate normally, but only give a reading accounting for all measurements being made?

    It's a well-known physical fact that "when we make any measurement, other aspects of a particle's character are changed". The only uncertainty in the measurement itself is in your understanding.

    You completely misunderstand. Physical facts are not subject to interpretation, even if the model used to explain those observations is. The data is the observed physical facts. These are not malleable by a model.

    You obviously don't understand how science is done.

    Relativistic mass is only relativistic energy/c², and there is no controversy over the use of relativistic energy. As long as you actually understand it, the pedagogical issue is moot. Quite aside from all this only being a red herring meant to impugn a valid reference.
     
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