Quizzes & Puzzles5 mins ago
Now You See Me, Now You Don't - Huh???
14 Answers
I fear I'm using the minds of AB before picking up a book again, but from my limited exposure to literature and documentaries of Quantum Mechanics Uncertainty Principle, I have hit a philosophical conundrum...
It has been proven that electrons fired from a gun at a wall through a divider with two slits in it, can create both a particle like pattern on the wall (i.e. two long impact sites which correspond the the gaps in the divider,) and also multiple long impact sites which form as a result of a wave passing through the divider, amplifying and cancelling out compatible and conflicting wave peaks and troughs.
The electrons exert this wave-like behaviour when "not being observed"... Does this mean when in the dark (therefore no photons hitting it and returning to our eyes, or does it mean (what I hope it doesn't) that regardless of the conditions, by a life-form observing it, it snaps back into being a particle again?
Is it really only when an observer looks at it, or would the wave return to a particle if the experiment were lit but not observed?? Help!?
IHI
It has been proven that electrons fired from a gun at a wall through a divider with two slits in it, can create both a particle like pattern on the wall (i.e. two long impact sites which correspond the the gaps in the divider,) and also multiple long impact sites which form as a result of a wave passing through the divider, amplifying and cancelling out compatible and conflicting wave peaks and troughs.
The electrons exert this wave-like behaviour when "not being observed"... Does this mean when in the dark (therefore no photons hitting it and returning to our eyes, or does it mean (what I hope it doesn't) that regardless of the conditions, by a life-form observing it, it snaps back into being a particle again?
Is it really only when an observer looks at it, or would the wave return to a particle if the experiment were lit but not observed?? Help!?
IHI
Answers
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I've never been too shocked by Quantum Mechanics, which in view of that quote by the great Bohr has also had me worried why I don't! The way I've always thought of it, and I don't know how true this is or not, is that the particle-
00:53 Thu 28th Feb 2013
They "are" neither one thing nor the other. For certain experiments, the wave mathematics correctly predicts the result. For certain others, the particle mathematics works. Whether the electrons actually are one of those things, or the other, or are something else with the ability to behave as either, is an unanswerable question at present.
No it doesn't mean in the dark, it means as long as you have not done something to detect which path the electron takes.
The thing is that our minds are limited and can think of an electron as either / or. Either it is a particle and we can cope with that idea and visualise it, or it is a wave and again we can cope with that idea and visualise it. But reality is not so kind. They are different viewpoints of the same thing and when we check for one state we find that, and when we check for the other we again find the state we look for. Particle / wave, seems to be the same thing.
The thing is that our minds are limited and can think of an electron as either / or. Either it is a particle and we can cope with that idea and visualise it, or it is a wave and again we can cope with that idea and visualise it. But reality is not so kind. They are different viewpoints of the same thing and when we check for one state we find that, and when we check for the other we again find the state we look for. Particle / wave, seems to be the same thing.
good explanation of the slit exp here:
http://
http://
I'm having to do a lot of bloody reading of research and conceptual theories just to keep up with your great minds AB!! Absolutely loving it though! :)
@Teddio - As I officially educated myself to the Anthropic Principle only a few days ago due to another thread I have, I can only imagine that the enigma I creates in this scenario is that all subatomic particles (e.g. electrons) would, without equipment to detect it, remain in a wave like state (I'm guessing here) and therefore without Human intervention, all matter at the subatomic level should behave like waves...? Interesting combination of the two principles.
I first got stumped by electrons all those years ago in school physics where I, as you, were taught the oddity that arises when you attempt to measure them. You can measure their speed, but not it's position but if you measure it's location, you can't tell how fast it's going... And for an electron (being the size that it is) whizzing around say a Hydrogen nucleus so fast that it forms a shell that makes it bounce off other atoms (as was taught to me) seems a stretch of the imagination. Does the Uncertainty Principle therefore allow me to think of the electron behaving as a wave, radiating around the nucleus, that forms an atom's barrier but equally at the same time (if located e.g. by another subatomic particle) has the properties of particle allowing it to be exchanged with other atoms or knocked out it's orbit? This makes more sense to me because a wave can be everywhere but a particle can't (or shouldn't)
@Teddio - As I officially educated myself to the Anthropic Principle only a few days ago due to another thread I have, I can only imagine that the enigma I creates in this scenario is that all subatomic particles (e.g. electrons) would, without equipment to detect it, remain in a wave like state (I'm guessing here) and therefore without Human intervention, all matter at the subatomic level should behave like waves...? Interesting combination of the two principles.
I first got stumped by electrons all those years ago in school physics where I, as you, were taught the oddity that arises when you attempt to measure them. You can measure their speed, but not it's position but if you measure it's location, you can't tell how fast it's going... And for an electron (being the size that it is) whizzing around say a Hydrogen nucleus so fast that it forms a shell that makes it bounce off other atoms (as was taught to me) seems a stretch of the imagination. Does the Uncertainty Principle therefore allow me to think of the electron behaving as a wave, radiating around the nucleus, that forms an atom's barrier but equally at the same time (if located e.g. by another subatomic particle) has the properties of particle allowing it to be exchanged with other atoms or knocked out it's orbit? This makes more sense to me because a wave can be everywhere but a particle can't (or shouldn't)
With our current understanding, it is both a particle and a wave.
There has been no physical law postulated that makes this impossible or even highly improbable, so until there is we just have to accept that the properties of some particles have at least a duality in their behaviour. We may yet discover more dimensions to the way that matter behaves.
There has been no physical law postulated that makes this impossible or even highly improbable, so until there is we just have to accept that the properties of some particles have at least a duality in their behaviour. We may yet discover more dimensions to the way that matter behaves.
I've never been too shocked by Quantum Mechanics, which in view of that quote by the great Bohr has also had me worried why I don't!
The way I've always thought of it, and I don't know how true this is or not, is that the particle-like nature of an electron was only ever an approximation. A thumping good one, that works very well in most cases, but an approximation nonetheless. But when you start probing the electron at scales comparable to its "de Broglie wavelength (which is Planck's constant divided by the momentum)", you have to stop using the particle approximation and start inputting the wave-like behaviour. Hence all the weird double-slit effects.
One problem with this approach is that it's probably a bit too mathematical. But then, hey, every theory of physics, which is ultimately expressed using maths, has some crazy stuff coming out of it if you start trying to turn that maths into Physics. The problem simply is that words are totally inadequate to describe what is going on at a quantum level. So while I wouldn't say "Don't try", certainly you have to be aware of the limits of words to describe this.
Anyway, rather than assume that the electron is a particle with wavelike properties or a wave with particle-like properties and somehow jumping between the two, it might be easier to think of it as always a wave, but that in some cases the wave-like behaviour is ignorable. Rather like how you can treat an atom as just a single entity, but as you probe deeper you have to take the nucleus and electrons separately -- and then of course deeper still the nucleus splits into protons and neutrons, which in turn are made of quarks and gluons, and in turn maybe these are made from strings... but all of this fine structure can just be ignored when you perform experiments that just aren't sensitive to that for whatever reason.
Anyway, that's the jim360 interpretation. It might be complete bilge, I hope it isn't. Might not even be original but it is at least independently thought of (I think!). And it has the advantage of avoiding some of that particle -> wave jump and back. It never stopped being a wave. You just stopped caring.
The way I've always thought of it, and I don't know how true this is or not, is that the particle-like nature of an electron was only ever an approximation. A thumping good one, that works very well in most cases, but an approximation nonetheless. But when you start probing the electron at scales comparable to its "de Broglie wavelength (which is Planck's constant divided by the momentum)", you have to stop using the particle approximation and start inputting the wave-like behaviour. Hence all the weird double-slit effects.
One problem with this approach is that it's probably a bit too mathematical. But then, hey, every theory of physics, which is ultimately expressed using maths, has some crazy stuff coming out of it if you start trying to turn that maths into Physics. The problem simply is that words are totally inadequate to describe what is going on at a quantum level. So while I wouldn't say "Don't try", certainly you have to be aware of the limits of words to describe this.
Anyway, rather than assume that the electron is a particle with wavelike properties or a wave with particle-like properties and somehow jumping between the two, it might be easier to think of it as always a wave, but that in some cases the wave-like behaviour is ignorable. Rather like how you can treat an atom as just a single entity, but as you probe deeper you have to take the nucleus and electrons separately -- and then of course deeper still the nucleus splits into protons and neutrons, which in turn are made of quarks and gluons, and in turn maybe these are made from strings... but all of this fine structure can just be ignored when you perform experiments that just aren't sensitive to that for whatever reason.
Anyway, that's the jim360 interpretation. It might be complete bilge, I hope it isn't. Might not even be original but it is at least independently thought of (I think!). And it has the advantage of avoiding some of that particle -> wave jump and back. It never stopped being a wave. You just stopped caring.
Seemed good to my non-expert eyes Jim. Only thinkg that trips me up is the idea of it it being easier to think of it as always a wave. Give it a single slit to fire through and it appears to mock that viewpoint, not sufficiently spreading itself out having got through. Reality is weird, seems to be able to do everything any time it decides to.
Well that's OK because waves exhibit the same behaviour when passing through a wide slit. The rule is broadly speaking that waves "notice" that they have passed through a slit only if the slit width is similar to the wavelength. So fire an electron through a single (large) slit and it will behave "as a particle" because the wave effects wont be significant.
I'm not sure how "real" the wave is, so that to say that an electron is a wave might actually be dangerous. So a slight revision might be to say that the electron "behaves" as a wave always but you just sometimes don't need to care about that.
I'm not sure how "real" the wave is, so that to say that an electron is a wave might actually be dangerous. So a slight revision might be to say that the electron "behaves" as a wave always but you just sometimes don't need to care about that.
Ah now this *is* a very very good question.
Essentially you're asking what qualifies as an observer in the sense of quantum mechanics.
The wavefunction collapses when the results are measured, that is the result is distinguishable - it does not have to be observed by a real concious observer
This question was answered on this website more eloquently than I have here!
Essentially you're asking what qualifies as an observer in the sense of quantum mechanics.
The wavefunction collapses when the results are measured, that is the result is distinguishable - it does not have to be observed by a real concious observer
This question was answered on this website more eloquently than I have here!
You definitely need more science and not Jane Austen either
The dual nature doesnt mean a switch from one to the other (same mistake made in org chem and canonical forms - which dont whizz from one to the other). Sometimes the wave nature is good at explaining things - like the double slit expt and sometime the particle - to explain why the kids toy of vanes in a glass bottle whizz around
de Broglie thought it was a wave with a particle like a surfer in the middle, which is kinda where you are at, but it clearly (1925) wasnt.
Anyway have you read John Barrow's Infinity ?
A bit about it there
The dual nature doesnt mean a switch from one to the other (same mistake made in org chem and canonical forms - which dont whizz from one to the other). Sometimes the wave nature is good at explaining things - like the double slit expt and sometime the particle - to explain why the kids toy of vanes in a glass bottle whizz around
de Broglie thought it was a wave with a particle like a surfer in the middle, which is kinda where you are at, but it clearly (1925) wasnt.
Anyway have you read John Barrow's Infinity ?
A bit about it there
OH THAT Niels Bohr quote....
I thought you meant the one that said I am interested in those statements and their converses which are true at the same time.
which is almost what we have here
blows a hole in mathematical logic which he clearly hadnt done
as it means you can prove anything - anything at all (weak inconsistency condition)
I thought you meant the one that said I am interested in those statements and their converses which are true at the same time.
which is almost what we have here
blows a hole in mathematical logic which he clearly hadnt done
as it means you can prove anything - anything at all (weak inconsistency condition)
Problems arise when you begin to think of photons as things in and of themselves rather then interactions between things, interactions that in the interim are non-local and non-temporal. Cause & effect do not exist independently but are rather inter-determinent.
Here's another way of 'looking' at it - http://
Here's another way of 'looking' at it - http://
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