QM randomness...

Discussion in 'Physics & Math' started by Seattle, Jun 2, 2017.

  1. Geon Registered Member


    Well, we've confirmed this effect now, so despite what you might hear, it does happen and can happen.

    The evolution of a wave function is affected - the Zeno effect is a phenomenon when a system is measured in intervals smaller than the half life of the system.
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  3. Geon Registered Member

    No, we measure the effects of decay, we don't watch an atom to see the radiation it gives off.
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  5. iceaura Valued Senior Member

    No, you can't.
    For starters: you cannot measure continuously, in theory.
    The Zeno effect is a change in a probability distribution - which becomes {zero/one} only in the limit.

    When you have adjusted to that, you can consider what is involved - theoretically, mind - in producing and maintaining distinguishable quantum states of an unstable atom while measuring that atom.
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  7. Geon Registered Member

    What's your objection? Exactly?

    Are you just being a tr0ll? Who said anything about measuring continuously... You are arguing either for the sake of arguing, or you have only read up on it now and trying to find semantic arguments to make it look like you know what you are talking about.

    You argued with me over my statement that by measuring a system, an atom can be indefinitely capable of becoming stable. I specified this required a measurement of the system before it has reached its half life, so what exactly are you arguing for?
  8. iceaura Valued Senior Member

    You did. You claimed the Zeno Effect means we could, in theory, create an "infinitely stable" atom of any kind by measuring it (post 276).

    I pointed out that you can't - that theory does not allow that. That was from memory.

    You referred me to the "zeno effect", which you regarded as support for your claim.

    I checked my memory, in case I had forgotten or mistaken something - no, as recalled that would involve measuring continuously, "in the limit". (That limit is zero, because the probability of decay is proportional to the square of the linearly decreasing time interval, but the probability of decay is not zero for any non-zero interval of time).

    You can't measure continuously, in theory. That is not the only theoretical impossibility you overlooked in making that claim, but it was immediate.

    The more relevant point, that the analysis producing the recognition of such an effect depends on assuming random behavior of the unstable atom, and is invalid under cause/effect presumptions - the entire calculation is of a probability distribution - is worth attending as well.
    Last edited: Sep 4, 2017
  9. Geon Registered Member


    No I just didn't specify that part. You did... and then after that, making it out it is some kind of mistake. I was quite aware that it is periodic measurements. But I am explaining subjects that really don't require that kind of depth, when people are struggling already with terminology.

    Good for you, yes, if this has made you feel good mentioning this, that's great.
  10. iceaura Valued Senior Member

    Then you were aware that it does not support your claim?
    Your claim was false, see. Nothing is going to support it.
    Making false claims and incorrect assertions is not recommended, when explaining things to people. It is even less recommended when attempting to argue toward a conclusion.

    And if your goal is clarity, irrelevant muddles like this
    seem oddly frequent. Now we are talking about half lives, for some reason? Another probability distribution, of course, but we have plenty of those.
    Last edited: Sep 4, 2017
  11. Geon Registered Member

    Well actually, no, if you mean my statement about an atom remaining infinitely stable in theory... well yes it is true actually.

    You actually have no idea what you are talking about do you? You can continue making those measurements indefinitely, what part of that do you not understand? You can completely freeze the evolution of the atom for as long you want so long as you are willing to make the measurement at the right time.

    This is why physicists tend to call the phenomenon

    ''a watched pot never boils.''

    So try again.
  12. Geon Registered Member


    ... What false claims? You're ranting about rubbish. I have made no false claims over the phenomenon... it appears though, you do not fully understand it.
  13. iceaura Valued Senior Member

    In every measurable non-zero interval of time, an unstable atom has a non-zero probability of decay, in theory. True or false?

    If true:
    You can't measure frequently enough to prevent its decay with probability 1. Not even in theory.
    You can't measure precisely enough and quickly enough to avoid leaving measurable intervals of time in which the atom is unmeasured. Not even in theory.

    And if you could, you would still have done nothing except alter a probability distribution. You needed causality, remember?

    edit in: Here's how people explain this situation without making false claims: http://news.cornell.edu/stories/2015/10/zeno-effect-verified-atoms-wont-move-while-you-watch
    Last edited: Sep 4, 2017
  14. Geon Registered Member

    I'm not getting into the rest of the nonsense, this is a straightforward question:

    True. In fact, each time you measure the particle, you measure it from its initial state. Do it frequently, the atom will never change from its initial state. It has to be fast enough, so that you make a measurement before it reaches its half life, otherwise, it may result in an increase of decay from radiation called the anti-zeno effect.

    Wiki sums this up concisely:

    ''the Zeno effect can be defined as a class of phenomena in which some transition is suppressed by an interaction — one that allows the interpretation of the resulting state in the terms transition did not yet happen and transition has already occurred, or The proposition that the evolution of a quantum system is halted if the state of the system is continuously measured by a macroscopic device to check whether the system is still in its initial state.[32]''
  15. Geon Registered Member

  16. iceaura Valued Senior Member

    Read the damn articles, will you? You have, at some time, taken a basic, introductory class in single variable calculus?
    They are taking a limit. You know how that works?

    The probability of decay does not go all the way to zero. The probability of finding the particle in its original state never reaches one. That is because the interval of time between any two measurements never goes to zero, and the number of measurements over any span of time is bounded below as well as countably finite. That is because of factors encapsulated in established theory, which prevent - in theory - continuous physical measurement of physical reality.

    To clarify the statement that has apparently confused you: "A continuously watched pot never boils".

    Briefly: in modern established theory, as well as in what we know of the world not what we don't, there is no such thing as a continuously watched pot. It's a theoretical impossibility, and its nonexistence has been demonstrated in many real world situations.

    Furthermore, declaring this to be "nonsense" hardly addresses your problem:
    You don't have a cause, or even a candidate, regardless of the probability distribution you have established. And the conflicts between your intuitive notion of "cause" and what you would need to explain Bell violations and the like remain unaddressed.
    Last edited: Sep 5, 2017
  17. Geon Registered Member


    Don't try and lecture me. Go read, why do you think physicists say, the atom will, and the key words here is

    never boil

    Do you understand what the adverb ''never'' means? And yeah, don't lecture me on the math. I actually understand it. I understand why it halts the evolution of the wave function. I understand why the measurements need to be taken before the half life of the particle and I also understand why this can be done ad infinitum for as long as we want. The only limit is when you stop doing the measurements.

    Up until that point, you will freeze an atom from radiating its energy. And listen very carefully when I read this out to you:

    ''But what happens if we repeatedly measure the state of the system or, to be more precise, if we measure its energy by applying H0 ? What happens if we continually watch the pot ? In classical physics this would make no difference, of course. An observation may be made without disturbing the system. But not so in quantum mechanics. It turns out that if we measure the system s energy state often enough, then its state will never change: a watched quantum pot never boils.''

  18. iceaura Valued Senior Member

    Yes. It's a figure of speech, however, not a rigorous description of the situation. The rigorous analysis and discussion in your articles describes approaching a limit.
    Including this:
    If you "continually" watched the pot, it would never boil.
    Remember when you posted this?:
    Now that you have read your link carefully, your link and your posting, you know the answer: Your sources, your links, your posts. Everyone who has analyzed or reported on the Zeno effect talks about taking the limit as the measurement interval goes to zero.

    Now, attend: you can't measure "continually", and the problem is theoretical - not just practical. Theoretically, it's impossible. Theory says you would have to violate established laws of nature and so forth to do that. There is a lower bound on the measurement interval, and it's not zero. And so the pot will boil, sooner or later, theoretically. Theory says the atom cannot be made "infinitely stable" by measuring it, because that would require "continual" measurement.

    So this statement:
    is a false statement.

    Is this now clear?

    Can we now move to the more significant matter: so what?

    You are barking up the wrong tree. No alteration of the probability distribution is going to magically hand you causality. Even the theoretically unachievable probability of one - an infinitely stable atom - leaves all of the problems with hypothetical causes untouched. You still have the Bell violations, the necessity of discarding things like standard logic or Relativity Theory or the notion that causes precede effects, and so forth.
    Last edited: Sep 6, 2017
  19. Geon Registered Member


    No actually, that's the fool in you. If you think physicists use ''figures of speech'' erroneously like this and carelessly like this, then you surprise me.

    No, I've had enough of you. You're not even listening to me.

    In fact... you're not just not listening to me, you are avoiding any actual scientific material drifted your way. You are nothing but a time-waster.

    Also, I say ad infinitum, but it depends on how you perform the measurements so that decay probability doesn't increase. But I did explain this before as well. Just so that people understand what is happening here, the very act of measurement disturbs the energy levels of an atom in such a way that the disturbance shifts the energy levels so that there are fewer electromagnetic modes at the appropriate energy, which in turn produces the Zeno effect. The probability of decay hasn't disappeared totally, there is still a chance that more modes at the appropriate energy, leading to the anti-Zeno effect. I say ad infinitum, only with exception of the second zeno effect.
    Last edited by a moderator: Sep 6, 2017
  20. Kittamaru Ashes to ashes, dust to dust. Adieu, Sciforums. Valued Senior Member

    Reiku's latest sockpuppet has been dismissed. Carry on.

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