Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: rocking_1987 on 30/07/2012 14:46:18
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HI,
I am really troubled with this QM. As per QM the particle will have tanglement effect which means if something happens with the particle on the earth than its counter part particle will do exactly the opposite.
Qm itself suggest that particles do not want to act in a perticular manner and they want to act as per their wish than how come they follows this tanglement effect all the time? WHy cant they do the same at their own same? Why they would make the effect as an eternal truth all the time?
Even if it is right. What happened to counterparts of the earth particles, which have been destroyed in an atomic bomb? Now whom do they follow?
black hole is created right after the supernova. If you look at the properties than the particles taking part in both events are doing exctly the opposite.
I mean in the supernova particles just get separated violantly and in the black hole they did exactly the opposite and they get togethar violantly.
for that instance the tanglement can be right but when blackhole eat some star than where is the super nova sort of event in the universe? Do we have any observation that whenever any star is engulfed by the blackhole, there is a supernova somewhere else just after that?
someone please help me, this driving me crazy
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HI,
I am really troubled with this QM. As per QM the particle will have tanglement effect which means if something happens with the particle on the earth than its counter part particle will do exactly the opposite.
Entanglement does not really work like this - although I cannot be surprised that you have read that it does, the incorrect ideas are everywhere. There is no instant communication. Entanglement is amazing - but not like that, sorry.
Qm itself suggest that particles do not want to act in a perticular manner and they want to act as per their wish than how come they follows this tanglement effect all the time? WHy cant they do the same at their own same? Why they would make the effect as an eternal truth all the time?
Without the instant communication over distances section; if one of a pair of entangled particle is disturbed or interacted with then the entanglement can be broken. they are not welded together for eternity - in fact one measurement will destroy the entanglement.
Even if it is right. What happened to counterparts of the earth particles, which have been destroyed in an atomic bomb? Now whom do they follow?
not every particle has a partner - only very few, carefully prepared particles or photons are part of an entangled pair
black hole is created right after the supernova. If you look at the properties than the particles taking part in both events are doing exctly the opposite.
I mean in the supernova particles just get separated violantly and in the black hole they did exactly the opposite and they get togethar violantly.
yep the stuff that is blown off continues away, the rest falls back in and continues to fall, and continues to fall. you could think of it in terms of escape velocity - we have launched a few rockets that have the speed to get away from the earth for ever, everything else falls back to earth; in a supernova everything is more extreme. entanglement does not link the sections that blast away and the bits that fall back
for that instance the tanglement can be right but when blackhole eat some star than where is the super nova sort of event in the universe? Do we have any observation that whenever any star is engulfed by the blackhole, there is a supernova somewhere else just after that?
quantum entanglement is a super small scale thing - it is def not responsible for creating a blackhole whenever a nova goes off or vice versa. A supernova is not a consequence of a black hole swallowing a star somewhere else in the universe. A supernova occurs because the nuclear reactor that is a star has reached a strange point; the star is normally so hot that it holds itself in shape against its own gravity- but as it cools it starts to shrink, in some cases with disastrous consequences
someone please help me, this driving me crazy
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Hi,
Thanks a lot for your reply. I have some more questions. Sorry but i cant control my curiosity. As you said only photons and some others can involve in the entanglement. Why only them? What kind of property allow them to get into such a werid situation?
Is it possible that we would have misunderstood the normal property of the photons as an entanglement? I mean it does not matter if you choose photon from here on the earth or somewhere in the universe. They will act same in same kind of situation. If you are able to measure the effect of one photon early, it is not going to change the normal behaviour of the other photon. It should react in the same way regardless of the measurment time.
what kind of proof do we have that proves, whatever effect we are seeing on the photons is becasue of the entanglement only and there is no other factor or force is there which force the other photon to do exactly the opposite?
For example in a hot temprature the behaviour of the electron will be totally opposite than in the cold temprature.
Moreover, if you look into a car tire's rim for sometime you can see that it is moving right but at perticular speed the very same rim will make you feel like that its moving on the left and right side at the same time. Moreover we cannot tell by looking into a full speed fan and say wheather its moving clockwise or anticlockwise. I have no idea how could anyone tell that entanglemented photons or electrons are moving on its orbit in the opposite directions.
Is it possible that we are looking at the tire' rim effect and said that photons or whatever is in entanglement effect and when the vision becomes clear we are saying that entanglement is gone? Are we looking at the complete effect and giving enough time to complete it?
This is just my curiosity and I will be really thank full if you choose to reply me. Man this is exiciting!
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what kind of proof do we have that proves, whatever effect we are seeing on the photons is becasue of the entanglement only and there is no other factor or force is there which force the other photon to do exactly the opposite?
Entanglement doesn't say that particles do exactly the opposite of each other. Entanglement is basically that when we create a pair of particles, we make it so that the results of a measurement on them are correlated in some way. If I had a pair of quantum coins, for example, I could set it so that coin 1 and coin 2 are always either both heads or both tails. I could then send my quantum coins across the universe from each other, and if you measure quantum coin 1 to be heads, then you know what someone measuring quantum coin 2 will find. If you were to instead measure the position of quantum coin 1, you'd know nothing at all about the position of quantum coin 2. All you know about is the variable you set up to be "entangled."
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Hi,
Thanks a lot for your reply. I have some more questions. Sorry but i cant control my curiosity. As you said only photons and some others can involve in the entanglement. Why only them? What kind of property allow them to get into such a werid situation?
As an example - one way we can entangle photons is to shoot one particular wavelength photon into a special crystal and we end up with two photons being produced with twice the wavelength (half the energy) AND whose polarizations are entangled (SPDC (http://en.wikipedia.org/wiki/Spontaneous_parametric_down_conversion)). Its not simple - its a complicated deliberate process.
Is it possible that we would have misunderstood the normal property of the photons as an entanglement? I mean it does not matter if you choose photon from here on the earth or somewhere in the universe. They will act same in same kind of situation. If you are able to measure the effect of one photon early, it is not going to change the normal behaviour of the other photon. It should react in the same way regardless of the measurment time.
Yes - but in order to be science we need to be able to test the difference..
what kind of proof do we have that proves, whatever effect we are seeing on the photons is becasue of the entanglement only and there is no other factor or force is there which force the other photon to do exactly the opposite?
We we have built a working quantum computer - admittedly only 8 qubits, but it is a start and it relies upon entanglement (it managed to factor 15 into 5 & 3 - little acorns etc)
For example in a hot temprature the behaviour of the electron will be totally opposite than in the cold temprature.
Nope its just more extreme in the hot temperature - the same rules govern both.
Moreover, if you look into a car tire's rim for sometime you can see that it is moving right but at perticular speed the very same rim will make you feel like that its moving on the left and right side at the same time. Moreover we cannot tell by looking into a full speed fan and say wheather its moving clockwise or anticlockwise. I have no idea how could anyone tell that entanglemented photons or electrons are moving on its orbit in the opposite directions.
our prediction match experimental data - what more can we do?
Is it possible that we are looking at the tire' rim effect and said that photons or whatever is in entanglement effect and when the vision becomes clear we are saying that entanglement is gone? Are we looking at the complete effect and giving enough time to complete it?
This is just my curiosity and I will be really thank full if you choose to reply me. Man this is exiciting!
This is still cutting edge physics - but whilst there is still room for massive gains in knowledge, it doesnt mean the guys in the labs and at the blackboards are just guessing.
Enthusiasm and curiosity are two things that are indispensable in science! Keep asking questions and keep thinking hard about the answers.
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Yeah, JP :)
But the point with that entanglement is that it is the measurement that 'instantly' will 'force' them into opposite relations, no matter what distance there is. So taking the coins you don't know what side they are on before you measure them, and no matter what side you find one of them to be in, you now 'know' that the other side must be represented by the other coin. And that phreaks me head out :)
How the he* does that other coin 'know', when no observer could know before hand?
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Yoron - there is no 'knowledge' there is just constancy. I could give you a coin in a nice presentation box that was entangled with mine - if you then took the coin to Peru; when you opened the box and saw a head you would know instantly that I had a tail (or whatever depending on the method of entanglement). Its the guarantee we can make that if A is a then B must be a' - no matter how far separated.
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Yeah, JP :)
But the point with that entanglement is that it is the measurement that 'instantly' will 'force' them into opposite relations, no matter what distance there is. So taking the coins you don't know what side they are on before you measure them, and no matter what side you find one of them to be in, you now 'know' that the other side must be represented by the other coin. And that phreaks me head out :)
How the he* does that other coin 'know', when no observer could know before hand?
This might be nitpicking, but it's causing the original poster confusion: entanglement does not force things into opposite states. Entanglement means you set up the particles so that there is a correlation between measurements of some parameter. This correlation could be between opposite states, or it could require that particles be in the same state. It doesn't have to be a 100% correlation. It might be that if I measure heads, you measure tails 51% of the time rather than the 50% random chance would give.
Entanglement lost a lot of its "magic" for me when I learned that you need to set up the quantum state by putting these correlations into it when you build it. It is certainly still very very weird (and non-classical), but you force these particles to be correlated when you make them, then you send them far apart. Its no wonder that when you measure them, they're correlated.
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Entanglement lost a lot of its "magic" for me when I learned that you need to set up the quantum state by putting these correlations into it when you build it. It is certainly still very very weird (and non-classical), but you force these particles to be correlated when you make them, then you send them far apart. Its no wonder that when you measure them, they're correlated.
But even if the magic has gone, things like Delayed Choice Quantum Eraser must still blow your mind a tiny bit?
The measurement of the entangled photon there seems to have profound consequences for something that has already happened
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All seems pretty straightforward to me :)
Obviously, the entanglement has created a sort of super-particle. Even when you split it apart, it is still a super-particle. The particle exists outwith our understanding of the dimensions of spacetime because the particle has its own dimensions.
If the stringy guys are not taking a hard look at entanglement, they might be missing the biggest clue to support their idea.
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Yeah, JP :)
But the point with that entanglement is that it is the measurement that 'instantly' will 'force' them into opposite relations, no matter what distance there is. So taking the coins you don't know what side they are on before you measure them, and no matter what side you find one of them to be in, you now 'know' that the other side must be represented by the other coin. And that phreaks me head out :)
How the he* does that other coin 'know', when no observer could know before hand?
This might be nitpicking, but it's causing the original poster confusion: entanglement does not force things into opposite states. Entanglement means you set up the particles so that there is a correlation between measurements of some parameter. This correlation could be between opposite states, or it could require that particles be in the same state. It doesn't have to be a 100% correlation. It might be that if I measure heads, you measure tails 51% of the time rather than the 50% random chance would give.
Entanglement lost a lot of its "magic" for me when I learned that you need to set up the quantum state by putting these correlations into it when you build it. It is certainly still very very weird (and non-classical), but you force these particles to be correlated when you make them, then you send them far apart. Its no wonder that when you measure them, they're correlated.
Are you thinking that although we can't know the 'spin' of the coins we do know that they are opposite, and that take the 'magic' away? But how do the other coin 'know' that first spin? Are you telling me that we also know beforehand the 'spin' of the coin we measure? The only way I can see that those 'outcomes' of first measurement doesn't involve a potent 'magic' :) is that we presume that the experiment 'force' the first measurement into just one type of spin, up, or down, so to speak?
I certainly agree with you in questioning the apparatus, I keep wondering about that as I come back to this.
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Maybe you are thinking of other types of correlation? It's become very popular to find 'entanglements' in all things there are those day, it seems?
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All seems pretty straightforward to me :)
Obviously, the entanglement has created a sort of super-particle. Even when you split it apart, it is still a super-particle.
This is a good way to think of it, Geezer. In classical mechanics, we can always think of 2 particles as 2 separate particles that, if they interact, do so by forces. In QM, entangled particles are actually 1 quantum state. You can't separate them into 2 particles interacting via some force--somehow they are one "superparticle."
I suppose why I'm saying you can remove the "magic" is that if you start from QM and accept that things like entanglement are part of nature, what becomes interesting is how these effects vanish as you go to large-scale (classical) objects. A lot of confusion comes from starting with classical mechanics and trying to make sense of entanglement in terms of classical ideas--especially since it has no counterpart there.
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The point I'm wondering about is this. Assume you correlate something, two coins, weighting the one you will measure on so that it always give you a 'head'. Then there is a 'smoke and mirrors' sort of magic. But if I do the same thing, not 'weighting' the one I will measure on, and so unable to say what the spin will be? How does the other 'knows' what the opposite is? You can either assume that there is some underlying reality in where this constant spin correlation finds a explanation, or?
It's 'magic' :)
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Yor_on, it's because it's all one quantum state. That state is: both are heads with 50% probability + both are tails with 50% probability. There is no classical version of this to fall back on for intuition, unfortunately--you couldn't do this with real coins.
It seems magical, since any classical coins that could do this would be magical. In the quantum world, this is just how nature works.
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Yeah, the funny thing though, assuming that QM and 'classical physics' somehow differ, whatever one want to put into that, is that 'distance' doesn't seem to matter for this correlation. We are used to thinking of QM as 'magnifying' the very small, but in this case, using the idea of a 'super particle', that particle can be seen as arbitrarily 'big'. And I agree Geezer, that's the way I think of it too, as 'one particle'.
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It isn't strange that QM and classical mechanics differ. Classical mechanics can be arrived at by taking certain limits of quantum mechanics (as things get big and interact with a lot of their neighbors), so its no wonder that some of the features of QM don't hold as you take those limits. You can still see QM effects on big scales if you're careful, which is what happens over large distances with entanglement, or what happens in Bose-Einstein condensates, for example.
Again, most of the confusion about how QM and classical mechanics can both be right comes from assuming classical mechanics is an accurate model and wondering how weird QM effects fit into it. Instead, QM is the more fundamental model, and classical mechanics can be derived from QM, and as part of that derivation, you lose some of the QM effects such as entanglement.
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Yoron - there is no 'knowledge' there is just constancy. I could give you a coin in a nice presentation box that was entangled with mine - if you then took the coin to Peru; when you opened the box and saw a head you would know instantly that I had a tail (or whatever depending on the method of entanglement). Its the guarantee we can make that if A is a then B must be a' - no matter how far separated.
Hi, sir.
I have one more difficulty to absorb this. My understanding tells me that i would know the result of side of the coin in Peru, if I have the other side of that coin in my box in Canada.
The question is how do you know that perticular coin is entangled with my coin only and not reacting to other coins or just being itself?
I mean How do you know that your coin is entangled with mine coin? How can you tell that untill you measure it in the first place? If you know that your coin is entangled with mine than why would you send the coin to the peru? What difference it will make?
I mean when you read the first result like this, My coin showed the tail and your coin showed head side right? When you put the coin in the box and open it in the peru than what difference it makes? It was, is and will always be tail if your coin is showing the headside.
Once you changed the side of the coin again than my coin will not react to that and their so called entanglement will be gone just because of so called measurment we took on your coin.
The electrons are present in the huge quantity. When we are seeing such a result then how come we can say that we looked and measured the very same electron? I mean when you put a coin in a box and other 1000 people did the same thing alternately (i mean 500 people will have head and other will have tail). As you will have me as your partner so do the other 1000 people will have.
If you put the 1001 boxes at the same place and let their partners to open their boxes than how do i and other know that which box is mine or their?
Or if you keep open all the boxes than how come me and other will determine that which coin is their? I mean if i have head and other guy should have tail. How come do we know that which perticular coin is mine? Now, for more complexation lets guess that 300 boxes( 150 coins have tail and other 150 coins have head) coin were not entangled and just kept in the boxes.
How do i know that whatever i have selected is in entanglement and not one of the coins which were just kept there.
I am really sorry for my english but its not my first language. I am just trying to get as more knowledge as possible and not trying to annoy anyone. Thanks
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The coin example we've been using is just for discussing the principle. The idea that is 'spooky' here is the one that no matter what side/spin the first coin is found to have, the other will have the opposite side/spin. And the coin you measure on is in a so called 'superposition' before you measure it. It has a 50% possibility to be 'spin up' or 'spin down', and it can't be 'decided/known' before you measure it.
If you imagine that the equipment/circumstances defining the experiment decide this, then you (most probably) will be wrong, at least as it seems from what we know today. It has a even probability to come up 'head or tail' every time you flip the coin, meaning that you can do 'identical experiments', finding different 'sides' showing up, with the other 'coin' always being the opposite. And if it is so then the question becomes 'how can that be?'
http://www.sciencenews.org/view/feature/id/65060/title/Everyday_Entanglement
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And entanglement are about correlating properties, when it comes to light as photons you can do it by using a beam splitter, a non linear crystal or 'half way mirror'. When you 'split' that original 'photon' in the half way mirror half the 'light' bounce back, with the other half passing through. Together those newly split 'photons' represent the original 'photon' before it was split, and it is down converted naturally (energy) as it becomes split. But somehow they still are connected by their spin/polarization as shown in experiments, and as there is a even probability for the photon you measure on to be 'spin up' or 'spin down' there is no known way for us to decide which 'side' it will be/have until measured. But there are other ways to entangle than by spin/polarization, I'm pretty sure JP could tell us a lot more about it than this :)
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HI,
I thought a little bit and my mind come up with this new thing, Let say entanglement is right and we can somehow know the result of the other coin.
Now guess that you have two entangled triangles. Lets mark the sides as A, B and C. what will happen in that case? I mean even if you know the result of one triangle (lets say A) than how would you able to know that other triagle will have side B or C?
I have read the article cited by you. You may not have the answer of the question but its worth to ask. In the article it says that slightest disturbance can brake the entanglement. If is it true that what kind of disturbance proof method did scientist used to send one photon from one place to another place?
As far as I know there is no method in the science which does not have the interfearance or disturbances.How come scientists were able to transport the entangled photons from one place to another?
If they are able to send it without any disturbances than why cant they send the daylight from one place to another without loosing it?
I mean is it possible to entangled the daylight photons somehow and create the same property in the photons present at the nighttime? ( I do understand the quantity limits but can we create the same property of the single daylight photon in a night-time photon?)
Can we say that the light beam is entangled all the time (as any of them will show the very same or opposite property untill you choose to measure it by using different methods) but its entanglement is disturbed by the prisms or whatever we are using to create entanglement?
Is it possible that what we are seeing is just a little part of undisturbed photons?
The major question is why do we have to create the entanglement? Why can't we see it in any natural phenomena? If it is a natural phenomena than we should not have to create it on the molecule levels.
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All seems pretty straightforward to me :)
Obviously, the entanglement has created a sort of super-particle. Even when you split it apart, it is still a super-particle.
This is a good way to think of it, Geezer. In classical mechanics, we can always think of 2 particles as 2 separate particles that, if they interact, do so by forces. In QM, entangled particles are actually 1 quantum state. You can't separate them into 2 particles interacting via some force--somehow they are one "superparticle."
I suppose why I'm saying you can remove the "magic" is that if you start from QM and accept that things like entanglement are part of nature, what becomes interesting is how these effects vanish as you go to large-scale (classical) objects. A lot of confusion comes from starting with classical mechanics and trying to make sense of entanglement in terms of classical ideas--especially since it has no counterpart there.
I'm probably missing something here, but isn't this a very powerful argument to support the existence of other dimensions - as in String Theory? Are the famous double-slit photon experiments another indication?
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I'm missing something (not an unusual state for me to be in)--why would having two particles acting as one imply extra dimensions?
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Sorry , I did not understand what you are trying to tell? Can you please bit explain it?
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When you have set the properties in a entangled system (half way mirror) both photons are entangled. To proof that you have a entanglement is difficult as a 'photon' by itself only exist in its 'creation', created by interacting with/in matter, and in its annihilation, which then becomes your measurement. As for the 'interference' I guess it depends on what will happen to those 'photons' as they move their separate ways after being split. I'm not fully sure myself what they mean by that as a photon either is 'there' and so able to be measured, or 'not there' which then presumably means that it has annihilated on the way (interacting with something). It may be they look at it as a 'wave' there, and that the 'wave' then changed on the way as in the idea of quantum cryptography . You need to read up on the wave/particle duality of light to see that one. But here is a very nice example of a entanglement. http://phys.org/news/2011-05-matter-matter-entanglement-distance.html
A BEC is a ultracold gas of atoms where all 'atoms vibrate' the absolute same, becoming as one 'super atom'. By sending in a 'photon' you can change the way it resonance, and then by interacting again with it (the BEC) using a laser make it send out a new photon of the exact same resonance/properties as that first 'photon' that was sent in 'tuning' the BEC.
So entanglements exist. Another even weirder idea is that you don't need to entangle those photons, electrons, atoms whatever. You just need to 'force' something (a photon, atom, etc) at A to behave the exact same as at B and then you have a same 'state' for them. It's called quantum discord.
"The degree of entanglement is often used as a figure of merit for determining its usefulness for quantum technologies. Strongly entangled systems, however, are very sensitive to extrinsic influence and difficult to prepare and to control. A team of researchers headed by the physicists Caslav Brukner (theory) and Philip Walther (experiment) at the University of Vienna have been able to show that in order to achieve successful remote state preparation entanglement is not the only way forward. Under certain circumstances, non-entangled states can outperform their entangled counterparts for such tasks - as long as they have a significant amount of so-called "quantum discord". This novel and not yet fully understood measure of quantum correlations quantifies the disturbance of correlated particles when being measured.
In their experiments, the researchers used a variety of two-photon states with different polarization correlations. "By measuring the polarization state of a certain photon we prepare the state of the respective partner photon remotely", explains Philip Walther. "In the experiment we observe how the quality of our remotely prepared quantum state is affected by changes in the quantum discord." This work provides an important and significant step towards future quantum information processing schemes that would rely on less demanding resources." by a team of researchers headed by the physicists Caslav Brukner (theory) and Philip Walther (experiment) at the University of Vienna.