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what happens when you shoot 2 lasers at the same spot?

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  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-21 19:29
    > out of the quantum uncertainty

    " Last call for alcohol ! "

    Even ignoring the beam splitters effect in causing correlations doesn't help. Hiesenburg's principle is certainly uncertain as we don't have *any* momentum or position. And we're not talking about probability amplitudes because there are no amplitudes to base the probabilities on! As I mentioned, it seems like a trick question - it really is. Phil's wagging the dog by asking, "So where does it go when the beams cancel?"

    We cannot assume that the beams cancel. This is the old "observable" problem in a different guise.

    I'd suggest for the next thought experiment Phil provides, we read a bit more carefully - otherwise, he's gonna be sitting at the bar again, laughing in his hat ;-P

    - H

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  • Carl HayesCarl Hayes Posts: 841
    edited 2009-07-24 21:04
    John R. said...
    If a tree falls in the forest and nobody hears it, does it still make a crash?
    This is a common logical trap.· When some people discuss it, they fool themselves into believing that they are questioning what happens in the forest.

    They are not questioning what happens in the forest.· All are in agreement -- a tree falls, and it causes vibrations.· There is not the slightest difference of opinion on this.

    What they are talking about is the definition of the word "crash".· The real question is simply, "Shall we agree that the word crash denotes these sudden vibrations in the forest, or shall we agree, instead, that we will use the word crash only when the vibrations are heard?"

    That seems a nit-picking distinction -- but it isn't.· Many people spend their whole lives in arguments that they think are discussions of physical reality, when really they're only talking about the definitions of words.

    Thiat's a waste of time and effort, because of the basic distinction:· physical reality exists independent of human opinion and human language, while the meanings of words depend only on agreement among their users.· Failure to understand this makes rational thought and discussion impossible.

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    · -- Carl, nn5i@arrl.net

    Post Edited (Carl Hayes) : 7/24/2009 9:10:15 PM GMT
  • mctriviamctrivia Posts: 3,772
    edited 2009-07-24 21:07
    But quantum mechanics says things are only definit when observed

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  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-07-24 23:23
    Carl, VERY well put. I've had some lengthy arguements with guys at school. Many of these guys think they are some sort of noble and great thinkers, when in reality they are arguing a play on words. You summed that up well.
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-24 23:53
    Carl> What they are talking about is the definition of the word "crash".

    Almost - that language "definitions" are the ultimate boundary of a problem was a fallacious argument Wittgenstein presented. It was essentially based on another erroneous idea *essentially* held by Hilbert and Russell: that the world could (eventually) be explained by symbolic manipulation alone. A stake was driven through the heart of those views held by the "logical positivists" by Kurt G
  • mctriviamctrivia Posts: 3,772
    edited 2009-07-25 02:01
    Well it will be observed
    The vibration from it hitting the earth can be measured world wide if we had machines sensitive enough and weren't doing anything else

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  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-25 22:34
    Indeed - and we measure things to help us understand *why and how* - not to answer "what shall we call it?"

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  • Carl HayesCarl Hayes Posts: 841
    edited 2009-07-26 03:10
    CounterRotatingProps said...
    Carl> What they are talking about is the definition of the word "crash".

    Almost - that language "definitions" are the ultimate boundary of a problem was a fallacious argument Wittgenstein presented. It was essentially based on another erroneous idea *essentially* held by Hilbert and Russell: that the world could (eventually) be explained by symbolic manipulation alone. A stake was driven through the heart of those views held by the "logical positivists" by Kurt G
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-26 15:44
    >... contrasting views of Logical Positivism.
    >Indeed, as I understand Logical Positivism, the example of Schr
  • Carl HayesCarl Hayes Posts: 841
    edited 2009-07-27 17:40
    CounterRotatingProps said...
    >... contrasting views of Logical Positivism.
    >Indeed, as I understand Logical Positivism, the example of Schr
  • chaosgkchaosgk Posts: 322
    edited 2009-07-27 18:16
    You simply need to understand "there is no spoon"


    Anyhow, I have a question getting out of the forest and back to the lasers.·
    What would happen if you had a perfect sphere with a mirrored surface on the inside and you find some way to get a laser light into it continuously without losing anything.· Assuming the inside of the ball is a perfect mirror that has no loss, will the ball store the laser energy? Say you use something big like a 50 watt laser and it does store the energy, what happens if the sphere is shattered?
  • mctriviamctrivia Posts: 3,772
    edited 2009-07-27 18:24
    Definetly theory since a mirror can not be both perfectly reflective and let light in.

    If putting light in pointed at center the light will bounce back and forth in a line. As you kept putting more energy in the ball would start to get hevier and if not broken eventually start a black whole.

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  • chaosgkchaosgk Posts: 322
    edited 2009-07-27 18:50
    Has it actually been proven that light does have mass and therefore weight? If light does not have mass, the ball would not get heavier, but the energy is never being released. Assuming the ball is storing all of the energy and is eventually broken say years down the road after getting mega or even giga watts pumped into it, would it be an explosion, something along the lines of a nuclear bomb without the fallout? If the energy could be stored and released in a controlled fashion, I think it would make one hell of a good battery. Unlimited storage with zero weight?

    Also since it is a mirrored ball, it shouldn't be reflected in a perfect line, it will go out of focus as soon as it hits the surface and most likely never be in focus again.

    Post Edited (chaosgk) : 7/27/2009 6:56:10 PM GMT
  • mctriviamctrivia Posts: 3,772
    edited 2009-07-27 18:56
    Yes that is what e=mcc means

    Energy and mass can change forms

    For example if you excelerate a particle to almost the speed of light you can keep pumping energy into it to try to make it go faster but more and more energy will convert to mass the closer you get. With the excelerators we have made we have been able to see this effect.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    propmod_us and propmod_1x1 are in stock. Only $30. PCB available for $5

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  • chaosgkchaosgk Posts: 322
    edited 2009-07-27 19:28
    Ok, so going off that, it would still take a massive amount of light energy to even begin to have any noticeable effect on the weight of the ball so it should still make a very efficient battery, still to be answered, what happens to all of that energy when the ball is smashed?
  • mctriviamctrivia Posts: 3,772
    edited 2009-07-27 20:01
    Well first as I said it is imposible to make perfect 1 way mirror

    As for what happens that depends partially on the size but you would likely. See 2 powerful beams leaving either end

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    propmod_us and propmod_1x1 are in stock. Only $30. PCB available for $5

    Want to make projects and have Gadget Gangster sell them for you? propmod-us_ps_sd and propmod-1x1 are now available for use in your Gadget Gangster Projects.

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  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-27 20:29
    Carl Hayes said...
    CounterRotatingProps said...
    >... contrasting views of Logical Positivism.
    >Indeed, as I understand Logical Positivism, the example of Schr
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-07-27 20:59
    It sounds to me as if logical positivism has a strong anthropocentric aspect to it. To accept this is to deny the cat any status at all as its own observer. Well, okay, let's build another box big enough for a human along with the box the cat is in. The human has a stethoscope and knows at any moment in time whether the cat is alive or dead but has no way to communicate this to the world outside his own box. Does this alter the cat's state in any way? Is it still a superposition? Or does the presence of a human — albeit incommunicado — observer in the box automatically cause the superposition to collapse?

    It seems to me that requiring a human observer sets ourselves on a rather high pedestal. But absent that requirement, what does it really mean to "observe"? And is a so-called "superposition" merely an expression of our ignorance and lack of observation, or is it a fundamental property of the system?

    -Phil
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-27 21:12
    Nicely put, Phil.

    It's pretty well known and accepted that the Copenhagen Interpretation of Q.M. presents this as a fundamental property of the system. Otherwise, why would Einstein and Schroedinger have been have been so annoyed by it? [noparse]:)[/noparse]) If it weren't, they'd have written it off, instead of exchanging mail over it for years.

    For the last 20 years, my favorite way of asking essentially the same thing as you've presented :

    What would happen if we replaced Schroedinger's cat with Schroedinger's brother?



    Here's an interesting site covering what many physicists have had to say:

    http://www.spaceandmotion.com/Physics-Niels-Bohr.htm

    [noparse]/noparse]EDIT: there's a glitch in that site, seems you've got to drill down into one bio first. Bohr has some fun stuff to say [noparse]:)[/noparse

    " The more success the quantum physics has, the sillier it looks ... God does not play dice with the cosmos."· - Albert Einstein

    " Einstein, don't tell God what to do ... It is wrong to think that the task of physics is to find out how Nature is. Physics concerns what we say about Nature.·" - Niels Bohr

    " Niels Bohr brainwashed a whole generation of physicists into believing that the problem (of the interpretation of quantum mechanics) had been solved fifty years ago. "· - Murry Gell-Mann (The man with "three brains each smarter than yours")

    - H

    (My cat, btw, is nick named "Schroedinger" [noparse]:)[/noparse])

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    Post Edited (CounterRotatingProps) : 7/27/2009 9:28:57 PM GMT
  • Carl HayesCarl Hayes Posts: 841
    edited 2009-07-27 22:18
    CounterRotatingProps said...

    (My cat, btw, is nicknamed "Schroedinger" [noparse]:)[/noparse])
    An acquaintance -- she and her husband are experts on fractals, and actually somehow make their living from fractals -- has a daughter named Julia.· She swears that her husband wanted, if the kid turned out to be a boy, to name him Mandelbrot.· She and I agree this would have been a disaster for the little guy.

    Phil, I disagree on the anthropocentricity of Logical Positivism.· As I understand it [noparse][[/noparse]that's not a trivial reservation], LP says that certain questions are meaningless not because they aren't resolved by observation, but rather because they can't be resolved by observation, not even in principle.· That is, if physical reality turns out the same whether a proposition is true or false, then that proposition says nothing about physical reality -- and any proposition that says nothing about physical reality truly says nothing about anything, has no meaning, because physical reality is the only thing that·can be examined.· This position has nothing to do with human beings, because cats -- even Schrödingers Katze can't resolve them by observation either, and neither can Kzinti or Martians.· So it ain't anthropocentric.

    It is, however, as you have now convinced me, a little different from that cat.· The cat is dead-or-alive-or-both-or-neither depending upon whether it actually is observed, rather than upon whether it can be observed; so you have changed my view a little.· Don't let it give you a big head.· turn.gif

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    · -- Carl, nn5i@arrl.net
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-07-27 22:36
    Carl,

    I rather suspect, then, that logical positivists have a heap of trouble with string theory! But that does bring up an interesting point: if a model of the universe requires the reliance on hidden (i.e. non-observable) dimensions to provide a complete explanation of the things we can observe, is that enough to discredit it from an LP point of view?

    -Phil
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-07-27 23:06
    I guess I've got a real problem with the whole notion of "observing". What does the term really mean? "To observe" presumes an "observer". But what qualifies as an observer? How smart does an observer have to be? Can a mole rat or a nematode be an observer? How about a virus or a non-lifeform? What change of state does it take to qualify as an "observation"? Carried to its logical conclusion, one might have to accept either that everything is observed all the time, or else nothing is.

    -Phil
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-27 23:18
    > Carried to its logical conclusion, one might have to accept either that everything is observed all the time, or else nothing is.

    Very good - and therein lies the Gordian's Knot of the Copenhagen View - the "observable" problem mentioned earlier.

    > What change of state does it take to qualify as an "observation"?

    All you have to be is a humble photon. [noparse]:)[/noparse])

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  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-07-27 23:22
    I think an observer is simply any sort of information outlet in a system. If information leaves a closed system, then something was "observed". An observer doesn't need a pair of eyes to see the event. It only needs to be informed some how.
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-27 23:39
    But you need a pair of eyes to *understand* the event, via the photon(s) which bring the event to your eyes. HOWEVER, that very same photon(s) AFFECTS the original system, and *changes* the state.

    So how do you know what *really happened* ? [noparse]:)[/noparse])

    [noparse][[/noparse]EDIT - there is no such thing as a closed system! Neither in Q.M. nor in relativistic physics. All you can do is limit and approximate. Every theory ever done was _bounded_. Then experiments show there·is something more - and the approximations have to get more precise and the boundaries have to be expanded.]

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    Post Edited (CounterRotatingProps) : 7/27/2009 11:44:45 PM GMT
  • Carl HayesCarl Hayes Posts: 841
    edited 2009-07-28 00:03
    Phil Pilgrim (PhiPi) said...
    Carl,

    I rather suspect, then, that logical positivists have a heap of trouble with string theory! But that does bring up an interesting point: if a model of the universe requires the reliance on hidden (i.e. non-observable) dimensions to provide a complete explanation of the things we can observe, is that enough to discredit it from an LP point of view?

    -Phil
    Depends on what is meant by "discredit".· LP doesn't discredit anything.· What it does do is say, for example, that·if·physical reality is the same whether string theory is true or not, then string theory doesn't say anything about physical reality.· Since physical reality is the only subject of string theory, if it doesn't say anything about physical reality, then it doesn't say anything at all.

    So, if string theory's truth or falsity doesn't affect anything in physical reality, then string theory, though it may be elegant and beautiful, has no (physical) meaning.· To me this seems to be the case.· When someone can make a testable (falsifiable) prediction from string theory, then it will have actual meaning.

    LP is mostly a way to avoid fruitless intellectual wheel-spinning.· Another example is described in Ambrose Bierce's Devil's Dictionary:
    Zenith, n. The point in the heavens directly overhead to a standing man or a growing cabbage. A man in bed or a cabbage in the pot is not considered as having a zenith, though from this view of the matter there was once a considerable dissent among the learned, some holding that the posture of the body was immaterial. These were called Horizontalists, their opponents, Verticalists. The Horizontalist heresy was finally extinguished by Xanobus, the philosopher-king of Abara, a zealous Verticalist. Entering an assembly of philosophers who were debating the matter, he cast a severed human head at the feet of his opponents and asked them to determine its zenith, explaining that its body was hanging by the heels outside. Observing that it was the head of their leader, the Horizontalists hastened to profess themselves converted to whatever opinion the Crown might be pleased to hold, and Horizontalism took its place among fides defuncti.

    Many of our controversies, and almost all religious ones, are of this kind -- string theory included.



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    · -- Carl, nn5i@arrl.net
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-28 00:13
    Perhaps we've reached the Zenith of the discussion? :-P

    er, no wait, that'd be:

    %-(|x|=0<

    RE: a child named Mandelbrot.

    Yikes! Well, guess that's better than Frank Zappa's naming his daughter "Moon Unit" [noparse]:)[/noparse])

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  • Ole Man EarlOle Man Earl Posts: 262
    edited 2009-08-07 03:29
    You guys been looking at my 3D laser projection holographic TV (digital of course)?
    Ole Man Earl
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-08-07 04:33
    Ole Man Earl said...
    You guys been looking at my 3D laser projection holographic TV (digital of course)?
    Is it a Zenith?

    -Phil
  • Ole Man EarlOle Man Earl Posts: 262
    edited 2009-08-08 03:20
    No, the tag on the back says %-(|x|=0<
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