There's nothing wrong with an appeal to authority when those you appeal to are, in fact, authorities on the subject in question. In this case, quantum physicists doing quantum physics. If another physicist comes along with another paper which gives me adequate cause to doubt the results of this experiment, I shall do so.
so you could never guarantee that it's the same neutron you're measuring.
Sure you can - just use one neutron. I thought the problem was that, while you can measure the neutron and know instantly what your partner will have measured, this doesn't allow communication. It's like two people listening to the same radio broadcast. They both have the same information (and can know [well, assume with a high degree of confidence, technically] that they both have it) but there's no way to use this knowledge to pass information between each other.
Knowing if a particle's wavefunction has been collapsed by a measurement would be useful, but I gather that's not possible either.
Furthermore, versions of the experiment that include particle detectors at the slits find that each photon of light passes through one slit (as would a classical particle), but not through both slits (as would a wave).
That doesn't mean that in versions without particle detectors the photons don't go through both slits.
Any photons which are detected are forced to have gone through one slit or the other. If the detectors are 100% efficient, all the photons will be absorbed so there'll be no interference pattern to detect. If the detectors aren't 100% efficient (or not present) any undetected photons will go on to produce the interference pattern - meaning they must have gone through both slits (since the experiment produces the same result when photons are emitted one at a time).
The experiment might have been interesting if the scientists had shot single neutrons instead of stream of multiple neutrons.
It still is interesting, because (as I understand it) they detected the presence of neutrons only in one arm and their spins only in the other.
Because, quoting the article [...] [t]hey find evidence of presence of neutrons in one arm (obviously, since they are in both arms)
Reading through the paper - which, admittedly, is mostly beyond me - suggests that while they were able to measure the particle's spin in path I and location in path II, they weren't able to measure the spin in path II and the location in path I. So the neutrons aren't "in" both arms.
From the paper:
We observe that an absorber in path I does not change the measurement outcome, while a magnetic field does. In contrast to that the absorber has an effect in path II, while the magnetic field has none. The neutrons behave as if particle and magnetic property are spatially separated while travelling through the interferometer.
There's also an earlier bit which says:
This [the use of absorbers in the paths] already tells us that the neutrons' population in the interferometer is obviously higher in path II than it is in path I.
-----
The result is so blatantly obvious.
Isn't it likely that the reason it seems so blatantly obvious is that you haven't understood what they claim to have achieve?
In that case the article is utter crap for not mentioning it.
There's only so far a science article written for the interested layman (and quite possibly by an interested layman) can go in explaining what has actually been done. Asking questions when an article has left you nonplussed is laudable, but to more or less denounce the experiment based on said article when you don't have the requisite knowledge* to fully understand the paper seems churlish.
*You might be Brian Cox for all I know, but I hope you won't take offence when I assume you to be just another interested layman like myself.
Personally i dont even understand why those guys are thinking they are measuring the properties of the same neutron.
(Most insightful part of comment highlighted.) Because they're scientists with more knowledge of physics than you or me?
I don't understand why you'd automatically assume they haven't measured the same neutron. When someone with more physics degrees than me makes a new claim about physics, I tend to default to the understanding that I'm not entirely qualified to go jabbering on the internet that they've probably just got it wrong - certainly without giving any reason beyond "I don't get it so it can't be right."
Perhaps they have got it wrong; time will tell. I think it's safe to assume that at the very least they remembered to rule out the obvious alternative explanations before publishing.
Officer Laura Martin was not fired but promoted this year. Here she is, standing bravely alongside Dallas Police Chief David Brown. But do you see fear behind her eyes?
I was pretty clear on all accounts, try to reread it again.
You may believe you were, but you were not. Simply suggesting I "reread it again" when you could instead answer some of my simple direct questions is being disingenuous.
you believe Wiki is a source of truth for Logic
Don't tell me what I believe (you shouldn't state as anything as fact without evidence). I used Wikipedia because it was a handy source for a reasonably decent defintion or r.a.a. that I thought anyone reading this discussion could understand without too much trouble. I've understood and used r.a.a. as a logical tool since about five years before Wikipedia came into existence. I could also point you at the Internet Encyclopedia of Philosophy's page on r.a.a., or The Free Dictionary's.
reductio ad absurdum, (Latin: “reduction to absurdity”), in logic, a form of refutation showing contradictory or absurd consequences following upon premises as a matter of logical necessity.
In common speech the term reductio ad absurdum refers to anything pushed to absurd extremes.
There's your definition at the end. In common speech. Not formal logic; common speech. It's like when people misuse "begging the question." It has nothing do with logic. This is exactly the sense in which you used it. It can't be anything else because I wasn't making any kind of logical conclusion when you used it. You thought I'd said something absurd and you grasped for a clever-sounding latin phrase that you - wrongly - thought was appropriate.
I can't find anything to support your view of r.a.a as a logical fallacy. Can you provide anything?
As stated, read a text book on Logic (my text books are well over 500 pages each) and actually attempt to "learn" the subjects. Or don't and continue believing that an opinionated summary makes you intelligent.
Am I supposed to be impressed that you have big text books? It's not "subjects"; it's a single term under discussion. I don't need to read a dozen books to understand what reductio ad absurdum is, because I've understood it perfectly since I was taught how it could be used to prove that the square root or 2 is irrational nearly 20 years ago. How can the application of a logical fallacy prove a mathematical truth?
You didn't get your version from The Big Bang Theory, did you? They appear to have made the same mistake.
Very common today that people believe that simply looking at a Wiki or Google result gives them knowledge, and it does anything but present "knowledge".
As opposed to reading an interview with someone who worked on a quantum computer, and extrapolating from what at this point I can only categorise as an anecdote (an anecdote of an anecdote, in fact) that "we can change quantum events by thinking about them" and stating the same as a fact, despite having no evidence in support of that view?
Not quite as bad as diving into a discussion on the holographic principle and declaring it to be poppycock without even taking the time to find out what the holographic principle is, but still...
Slashdot Mirror
They haven't even ever quantum entangled something as large as a neutron.
From Wikipedia (although I'm not exactly sure what "has been demonstrated with" means):
...has been demonstrated experimentally with photons, electrons, molecules the size of buckyballs
There's nothing wrong with an appeal to authority when those you appeal to are, in fact, authorities on the subject in question. In this case, quantum physicists doing quantum physics. If another physicist comes along with another paper which gives me adequate cause to doubt the results of this experiment, I shall do so.
so you could never guarantee that it's the same neutron you're measuring.
Sure you can - just use one neutron. I thought the problem was that, while you can measure the neutron and know instantly what your partner will have measured, this doesn't allow communication. It's like two people listening to the same radio broadcast. They both have the same information (and can know [well, assume with a high degree of confidence, technically] that they both have it) but there's no way to use this knowledge to pass information between each other.
Knowing if a particle's wavefunction has been collapsed by a measurement would be useful, but I gather that's not possible either.
Incorrect, quoting wikipedia:
Furthermore, versions of the experiment that include particle detectors at the slits find that each photon of light passes through one slit (as would a classical particle), but not through both slits (as would a wave).
That doesn't mean that in versions without particle detectors the photons don't go through both slits.
Any photons which are detected are forced to have gone through one slit or the other. If the detectors are 100% efficient, all the photons will be absorbed so there'll be no interference pattern to detect. If the detectors aren't 100% efficient (or not present) any undetected photons will go on to produce the interference pattern - meaning they must have gone through both slits (since the experiment produces the same result when photons are emitted one at a time).
The experiment might have been interesting if the scientists had shot single neutrons instead of stream of multiple neutrons.
It still is interesting, because (as I understand it) they detected the presence of neutrons only in one arm and their spins only in the other.
Because, quoting the article [...] [t]hey find evidence of presence of neutrons in one arm (obviously, since they are in both arms)
Reading through the paper - which, admittedly, is mostly beyond me - suggests that while they were able to measure the particle's spin in path I and location in path II, they weren't able to measure the spin in path II and the location in path I. So the neutrons aren't "in" both arms.
From the paper:
We observe that an absorber in path I does not change the measurement outcome, while a magnetic field does. In contrast to that the absorber has an effect in path II, while the magnetic field has none. The neutrons behave as if particle and magnetic property are spatially separated while travelling through the interferometer.
There's also an earlier bit which says:
This [the use of absorbers in the paths] already tells us that the neutrons' population in the interferometer is obviously higher in path II than it is in path I.
-----
The result is so blatantly obvious.
Isn't it likely that the reason it seems so blatantly obvious is that you haven't understood what they claim to have achieve?
In that case the article is utter crap for not mentioning it.
There's only so far a science article written for the interested layman (and quite possibly by an interested layman) can go in explaining what has actually been done. Asking questions when an article has left you nonplussed is laudable, but to more or less denounce the experiment based on said article when you don't have the requisite knowledge* to fully understand the paper seems churlish.
*You might be Brian Cox for all I know, but I hope you won't take offence when I assume you to be just another interested layman like myself.
Oh yes, and also:
The GP's question is valid and insightful, that's why it got moderated as such.
[...]
Appeal to authority is not good enough.
;)
He was asking...
That's kind of my point - he wasn't asking a question. He made a statement in what reads like a disingenuous tone ("i dont even understand why...")
I'm going to toss this out there but I expect the answer to be "no."
[...]
So am I wrong here
N... yes. Probably. But I don't know why, sorry.
This might help. Or it might not. It's late.
Personally i dont even understand why those guys are thinking they are measuring the properties of the same neutron.
(Most insightful part of comment highlighted.) Because they're scientists with more knowledge of physics than you or me?
I don't understand why you'd automatically assume they haven't measured the same neutron. When someone with more physics degrees than me makes a new claim about physics, I tend to default to the understanding that I'm not entirely qualified to go jabbering on the internet that they've probably just got it wrong - certainly without giving any reason beyond "I don't get it so it can't be right."
Perhaps they have got it wrong; time will tell. I think it's safe to assume that at the very least they remembered to rule out the obvious alternative explanations before publishing.
Do you circle a lot of people who will spam you?
That's not that game where everyone... never mind.
bigass truck.
http://xkcd.com/37/
The Pirate Bay co-founder Warg...
Is his name just "Warg," or this just a badly written summary?
Thank you
Thank you kindly.
I find the slow researcher withdrawal more than a little disconcerting.
All depends what you're researching and who with.
Many creatures today have coloring that makes no sense from a survival point of view but make perfect sense for getting laid
...therefore making (somewhat circular) sense from a survival point of view.
And for creating these Doctor Who titles.
Plus JC is on-board
I thought Jesus was my co-pilot. Two-timing bitch...
That explains why he failed to diagnose that guy with chronic truth-telling syndrome.
Like that'll ever happen. You post here all the damn time.
Officer Laura Martin was not fired but promoted this year. Here she is, standing bravely alongside Dallas Police Chief David Brown. But do you see fear behind her eyes?
No, no I don't.
you will find each and every single one of them love money.
How I know ? I am a Chinese.
All British people think that's a bit of a generalisation.
I was pretty clear on all accounts, try to reread it again.
You may believe you were, but you were not. Simply suggesting I "reread it again" when you could instead answer some of my simple direct questions is being disingenuous.
you believe Wiki is a source of truth for Logic
Don't tell me what I believe (you shouldn't state as anything as fact without evidence). I used Wikipedia because it was a handy source for a reasonably decent defintion or r.a.a. that I thought anyone reading this discussion could understand without too much trouble. I've understood and used r.a.a. as a logical tool since about five years before Wikipedia came into existence. I could also point you at the Internet Encyclopedia of Philosophy's page on r.a.a., or The Free Dictionary's.
Or here's a good one - Encyclopedia Britannica:
reductio ad absurdum, (Latin: “reduction to absurdity”), in logic, a form of refutation showing contradictory or absurd consequences following upon premises as a matter of logical necessity.
In common speech the term reductio ad absurdum refers to anything pushed to absurd extremes.
There's your definition at the end. In common speech. Not formal logic; common speech. It's like when people misuse "begging the question." It has nothing do with logic. This is exactly the sense in which you used it. It can't be anything else because I wasn't making any kind of logical conclusion when you used it. You thought I'd said something absurd and you grasped for a clever-sounding latin phrase that you - wrongly - thought was appropriate.
I can't find anything to support your view of r.a.a as a logical fallacy. Can you provide anything?
As stated, read a text book on Logic (my text books are well over 500 pages each) and actually attempt to "learn" the subjects. Or don't and continue believing that an opinionated summary makes you intelligent.
Am I supposed to be impressed that you have big text books? It's not "subjects"; it's a single term under discussion. I don't need to read a dozen books to understand what reductio ad absurdum is, because I've understood it perfectly since I was taught how it could be used to prove that the square root or 2 is irrational nearly 20 years ago. How can the application of a logical fallacy prove a mathematical truth?
You didn't get your version from The Big Bang Theory, did you? They appear to have made the same mistake.
Very common today that people believe that simply looking at a Wiki or Google result gives them knowledge, and it does anything but present "knowledge".
As opposed to reading an interview with someone who worked on a quantum computer, and extrapolating from what at this point I can only categorise as an anecdote (an anecdote of an anecdote, in fact) that "we can change quantum events by thinking about them" and stating the same as a fact, despite having no evidence in support of that view?
Not quite as bad as diving into a discussion on the holographic principle and declaring it to be poppycock without even taking the time to find out what the holographic principle is, but still...
You should totally click on this link. Your mom thought it was cool.
Warning: I heard you like warnings, so I put a warning on your warning so you can... uh... be warned of the warning.
Burma Shave.