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Post by Progenitor A on Mar 9, 2011 18:35:52 GMT 1
I can read, it's still [snip]! 2 or 2 billion, it's still nonsense, claiming that a watched atom doesn't decay. You're jolly unlikely to see ANY decays if you watch just two atoms of something with a long half-life, but that's just statistics, not some weird physical effect of watching stuff. You exhibit your typically anti-science stance where you mis-read what is written and then somehow you know, without needing any evidence at all That is why you continually make a fool of yourself and why there is an 'Idiot Science' thread Here we are once again : '2 or 2 billion, it's still nonsense, claiming that a watched atom doesn't decay. You're jolly unlikely to see ANY decays if you watch just two atoms You are so dogmatically [snip] that you do not even realise that you contradict yourself within 2 sentences, and this, even though you have previously ranted on (quite correctly as it happens)that if a photon is observed going through one of a pair of slits then the interference does not occur! You are no scientist my dear! radio4scienceboards.proboards.com/index.cgi?action=gotopost&board=talk&thread=657&post=8999
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Post by speakertoanimals on Mar 9, 2011 19:18:03 GMT 1
Decay is not the same as interference.
A photon in the two slit experiment IS in a superposition state, of passing through both slits, being both here and being there.
A nucleus that will decay is also in a state of superposition, of being both decayed and not decayed (as in schrodingers cat), not because you observe it, but because you don't! Hence watching an atom to see if it decays does nothing more than collapse the superposition, into either not decayed yet, or decayed, just as the associated cat is observed as being either alive or dead, and not in some weird superposition.
As for the radioactive nucleus, if I observed a year ago that it hasn't decayed, that means that if I go and observe it now, there will be a greater probability that the superposition which restablished itself after the last observation now collapses to give it as decayed, compared to if I had observed it as not decayed just a second ago. But this is accounted for by the normal superposition principle in quantum theory, and is just the half-life law in another form.
The comparison with the double slit (where observation at one slit destroys the interference pattern on the screen), is really no more odd than the fact that observing the atom as not having decayed at an earlier time changes the probability of observing that it HAS decayed at some later time, depending on when in the past the first observation occured.
So, if I know it hadn't decayed a year ago, the probability that it has decayed after I've waited another year to look again is going to give a greater probability of observing decay if I look now, because it had a whole year in which to possibly decay. (Note I say HAD decayed, not catching it in the process of decaying!). Whereas if when I checked a second ago, it hadn't decayed, its only had a second in which to possbly decay, as compared to a whole year.
Plus the totally obvious fact that if you have observed it as decayed at some earlier time, you can no longer expect to observe the same atom as NOT decayed at some later time.
The difference is that the observed states (decayed, not decayed) are the states in superposition, whereas in the double slit case, the superposed states (left slit, right slit) are different to the observed states (hits screen here, or there). Hence destroying the superposition by watching at a slit changes the outcome in the double slit, since BOTH left and right slit states contribute to each observed positional state. Whereas in the decay case, the observed and superposed states are the same.
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Post by Progenitor A on Mar 9, 2011 19:41:49 GMT 1
Decay is not the same as interference. A photon in the two slit experiment IS in a superposition state, of passing through both slits, being both here and being there. A nucleus that will decay is also in a state of superposition, of being both decayed and not decayed (as in schrodingers cat), not because you observe it, but because you don't! Hence watching an atom to see if it decays does nothing more than collapse the superposition, into either not decayed yet, or decayed, just as the associated cat is observed as being either alive or dead, and not in some weird superposition. As for the radioactive nucleus, if I observed a year ago that it hasn't decayed, that means that if I go and observe it now, there will be a greater probability that the superposition which restablished itself after the last observation now collapses to give it as decayed, compared to if I had observed it as not decayed just a second ago. But this is accounted for by the normal superposition principle in quantum theory, and is just the half-life law in another form. The comparison with the double slit (where observation at one slit destroys the interference pattern on the screen), is really no more odd than the fact that observing the atom as not having decayed at an earlier time changes the probability of observing that it HAS decayed at some later time, depending on when in the past the first observation occured. So, if I know it hadn't decayed a year ago, the probability that it has decayed after I've waited another year to look again is going to give a greater probability of observing decay if I look now, because it had a whole year in which to possibly decay. (Note I say HAD decayed, not catching it in the process of decaying!). Whereas if when I checked a second ago, it hadn't decayed, its only had a second in which to possbly decay, as compared to a whole year. Plus the totally obvious fact that if you have observed it as decayed at some earlier time, you can no longer expect to observe the same atom as NOT decayed at some later time. The difference is that the observed states (decayed, not decayed) are the states in superposition, whereas in the double slit case, the superposed states (left slit, right slit) are different to the observed states (hits screen here, or there). Hence destroying the superposition by watching at a slit changes the outcome in the double slit, since BOTH left and right slit states contribute to each observed positional state. Whereas in the decay case, the observed and superposed states are the same. You really are a scientific neophyte! The point is (and it is so obvious that it only has to be made to a child)that both phenomena are extremely unlikely and fly in the face of common sense Both are QM phenomena I assume the poster who informed us of that phenomenn has some evidence. Unlike you in your unthinking hidebound opposition
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Post by speakertoanimals on Mar 9, 2011 20:17:30 GMT 1
[snip]! That WASN'T the claim made which was that watched nuclei DON'T decay, not just that a few were unlikely to decay during any unreasonable period.
You're also wrong even on stats grounds, because with a half-life of 30 seconds or so, watching just two atoms, you'd have a damn good chance of seeing at least one decay if you watched for only 30 seconds, so not exactly extremely unlikely is it.......................
Nice to see that the finer points of the superpositions going on in decay and in interference totally passed you by (but then you've got no idea of even the basics of quantum theory, hence this silly recourse to totally incorrect supposed criticisms........).
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Post by Progenitor A on Mar 10, 2011 10:44:31 GMT 1
As for the radioactive nucleus, if I observed a year ago that it hasn't decayed, that means that if I go and observe it now, there will be a greater probability that the superposition which restablished itself after the last observation now collapses to give it as decayed, compared to if I had observed it as not decayed just a second ago. But this is accounted for by the normal superposition principle in quantum theory, and is just the half-life law in another form. So, if I know it hadn't decayed a year ago, the probability that it has decayed after I've waited another year to look again is going to give a greater probability of observing decay if I look now, because it had a whole year in which to possibly decay. Another prime piece of gobbldegook for the 'Idiot Science ' thread ;D ;D ;D ;D
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Post by abacus9900 on Mar 10, 2011 13:02:01 GMT 1
Why do I get the impression that the only reason STA posts here is to provide obscure explanations that most people find incomprehensible so as to be able to call people stupid and use the word 'b*ll*cks?'
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Post by petergriffin on Mar 10, 2011 14:32:23 GMT 1
STA, you may think that observing two atoms will still allow them to decay; however, I can assure you this is incorrect. I used the neon atoms as a reference to them had been made earlier. However, it would still stand which ever radioactive atom you use. This relates to the work done on Einstein-Bose condensate, where a very small number of atoms (only 10’s) are cooled to zero close to absolute zero and I mean very close within 1 part in a million close to absolute zero, these atoms are them watched with a laser. While they are being observed and temperature is raised the condensate will not boil, never, it does not. The same has been done for 10’s of atoms of radioactive elements, and while every atom is watched none of them ever decay. Your assumption that some will decay when not being watched is correct, but if you observe a radioactive atom, it will never decay, it cannot, it will not, never. If it did you would break the uncertainty principle, as you would know both position and momentum. See the Einstien-Podoskey-Rosen thought experiments which give similar situation and Bohr’s counter view. If you know better, publish the evidence and there is a good chance you’ll be off to Sweden to see the King and pick up your Nobel Prize.
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Post by principled on Mar 10, 2011 14:57:24 GMT 1
Very interesting post Peter. I'm travelling for the next day so would like to return to the thread in a couple of days. I still have a few questions to ask!!! P
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Post by speakertoanimals on Mar 10, 2011 15:38:32 GMT 1
No you wouldn't. You seem to be confusing the momentum of the observed atom (which may be unknown and unknowable), with the process of decay. I don't know WHY you think observing radioactive decay would violate the uncertainty principle. In fact, the finite lifetime of a radioactive nucleus gives (via the uncertainty principle), a finite width in energy, just as the lifetimes of excited electron states in an atom give rise to finite line widths for the observed photon spectrum. As regards the Bose-Einstein condensate, you seem to be confusing the collective atomic state of the atoms in the condensate, with the impossibility of nuclear transitions (decay). They are NOT the same, hence being in a BEC doesn't outlaw nuclear decay. The plots of velocity for the atoms in the BEc have nothing to do with the nuclear processes that may or may not occur............ I think you have just mixed up a whole load of things that are actually different. Indeed, rather than PREVENT decay, laser-trapping of short-lived radioactice nuclei such as sodium 21 has been done precisely BECAUSE it enables you to watch precisely the exact process of decay! A-Ha! A DIRECT refutation of this claim! Atomic physics experiments with trapped and cooled highly charged ions (2007) From the abstract: So, its been done, and uncertainty principle remains intact.... Perhaps you could provide a reference for your rather odd claim? I have seen papers which suggest a possible link between BEC and nuclear decay, but ONLY on the grounds of STIMULATING nuclear decay processes by the presence of a BEC: arxiv.org/PS_cache/atom-ph/pdf/9606/9606007v1.pdfAnd standard quantum theory. And certainly not the 'observed atoms don't decay' that you stated.
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Post by abacus9900 on Mar 10, 2011 18:40:42 GMT 1
"The process of radioactive decay is governed by the uncertainty principle, so that we can never say exactly when a particular nucleus is going to disintegrate and emit a particle. We can, however, give the probability that a nucleus will disintegrate in a given time interval. For a large number of nuclei we can predict what fraction will disintegrate during that interval. This fraction will be independent of the amount of isotope but will vary from isotope to isotope depending on its stability." chemed.chem.wisc.edu/chempaths/GenChem-Textbook/The-Rate-of-Radioactive-Decay-749.html
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Post by Progenitor A on Mar 10, 2011 20:53:30 GMT 1
STA, you may think that observing two atoms will still allow them to decay; however, I can assure you this is incorrect. I used the neon atoms as a reference to them had been made earlier. However, it would still stand which ever radioactive atom you use. This relates to the work done on Einstein-Bose condensate, where a very small number of atoms (only 10’s) are cooled to zero close to absolute zero and I mean very close within 1 part in a million close to absolute zero, these atoms are them watched with a laser. While they are being observed and temperature is raised the condensate will not boil, never, it does not. The same has been done for 10’s of atoms of radioactive elements, and while every atom is watched none of them ever decay. Your assumption that some will decay when not being watched is correct, but if you observe a radioactive atom, it will never decay, it cannot, it will not, never. If it did you would break the uncertainty principle, as you would know both position and momentum. See the Einstien-Podoskey-Rosen thought experiments which give similar situation and Bohr’s counter view. If you know better, publish the evidence and there is a good chance you’ll be off to Sweden to see the King and pick up your Nobel Prize. Can you supply references for this phenomenon Peter?
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Post by petergriffin on Mar 11, 2011 9:06:52 GMT 1
Naymissus & STA,
I have the references somewhere at home, I will dig them out over weekend.
I do recall it is only in respect of beta decay, this is why it is linked to uncertainty, as if you know when the electron (or positron) is emitted, and you know it mometum, you can then know both it position at mometum at point of emission.
I will dig out the stuff.
Have a good weekend.
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Post by speakertoanimals on Mar 11, 2011 16:25:08 GMT 1
I've come across some weird stuff as regards stimulated beta-decay (but unfortunatekly actual paper would not download, despite me having access via uni library).
I'mintrgued by this, and would be interested to know what it was that sparked the comment, but I can't find anything else myself. But I have discovered other interesting stuff in the process, so that is good!
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