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He doesn't use the word "splits". He says the experiment uses a :"crystal that absorbs an incoming photon and creates two new photons, each with 1/2 the energy of the original." That seems like a pretty good description to me.
originally posted by: Phantom423
I was watching the video "How the Quantum Eraser Rewrites Time" that someone else posted:
If you scroll to 4:30, he states that the BBO crystal splits a PHOTON into 2 new PHOTONS, each of 1/2 the energy of the original photon. Not sure this is correct.
Is it possible to split a proton into 2 equal parts?
It seems like your question is based on this word "splits" that he didn't say. He says that photon is absorbed by the crystal and two new photons emerge.(assuming you meant photon)
If he had said "split" I wouldn't fault him for that since it's common to dumb down the science a bit for presentations to the general public and say things that aren't quite right technically to get an idea across, and I suppose it depends on how you define "split" and what you mean by that term. Nature is an esteemed journal and they are using the term "split" to describe this process, but I think the descriptions in the delayed choice quantum eraser video and paper are more accurate and don't use that term.
Photons meet with three-way split
In the past, devices have been able to split a photon only into two. In the typical method used to achieve this, known as parametric down-conversion, a laser beam is shone into a special 'non-linear' crystal — crystals that exhibit unusual optical effects under intense laser light. Occasionally, a single photon from the beam converts into two photons, each with a portion of the original's energy and momentum.
Researchers have known that, in theory, it would be possible to split one of these new photons again in a 'cascaded down-conversion', making a total of three photons. But there has been a catch: the probability of one photon splitting is normally just one in a billion, making the probability of it happening twice in succession one in a billion billion. Experimentally, this has been too small to contemplate.
a reply to: Arbitrageur
The main point of the use of entangled pairs is to determine which slit without interfering?
Seems clever, except that entanglement messes it up because you still have to interfere with the twin so you get the same result as you do without using entanglement?
You lose the interference pattern even though you don't interfere with the photon which reaches the interference screen, because of pesky entanglement?
(question marks intended)
The main point of the use of entangled pairs is to determine which slit without interfering?
Seems clever, except that entanglement messes it up because you still have to interfere with the twin so you get the same result as you do without using entanglement?
You lose the interference pattern even though you don't interfere with the photon which reaches the interference screen, because of pesky entanglement?
(question marks intended)
edit on 11/25/2018 by Phage because: (no reason given)
a reply to: Arbitrageur
I agree with pretty much everything you, and Feynman, and the textbooks write concerning the electric dipole. Yes, the electric dipole is made up of two electric monopoles separated by a small distance, and since the electric monopole is the fundamental attribute in that case I would concur that the essence of the electric force does indeed fall off as 1/r^2. As such, if that were all there was to the story, a 1/r^2 force fall off could perhaps be a generalization of nature's laws, and perhaps gravity and electricity could be argued to be specific cases of a more general law. However, that is not all there is to the story, and my point is, to quote what I wrote above:
That is, my comment above is about the magnetic dipole, not the electric dipole. And it is there that the generalization from a discussion of gravity to all of nature's laws has difficulty in my view, since I don't believe there is any evidence at all for a magnetic monopole. That would make the magnetic dipole a fundamental attribute, and it does not lead to a force falling off as 1/r^2.
I agree with pretty much everything you, and Feynman, and the textbooks write concerning the electric dipole. Yes, the electric dipole is made up of two electric monopoles separated by a small distance, and since the electric monopole is the fundamental attribute in that case I would concur that the essence of the electric force does indeed fall off as 1/r^2. As such, if that were all there was to the story, a 1/r^2 force fall off could perhaps be a generalization of nature's laws, and perhaps gravity and electricity could be argued to be specific cases of a more general law. However, that is not all there is to the story, and my point is, to quote what I wrote above:
I pondered what Feynman is pondering, and then I came to realize that the magnetic dipole moment of the electron appears to be every bit as fundamental as its charge.
That is, my comment above is about the magnetic dipole, not the electric dipole. And it is there that the generalization from a discussion of gravity to all of nature's laws has difficulty in my view, since I don't believe there is any evidence at all for a magnetic monopole. That would make the magnetic dipole a fundamental attribute, and it does not lead to a force falling off as 1/r^2.
a reply to: Phage
In the delayed choice quantum eraser experiment, they are definitely interfering with the experiment when they manipulate the entangled partner, no question about that, but the timing is the interesting part of that experiment.
In a classical analogy lets say you fired two "entangled bullets" (there's no such thing but I'm just using this to help think about what is strange about the timing). Lets say one strikes screen A and the other strikes screen B at the same time. Aside from the mystery of how it can happen simultaneously, we could still try to visualize something like hidden variable linkages between the two things that allow manipulating one bullet to affect the outcome of the other bullet's impact on the screen.
Now let's say you fire entangled bullets at two screens spaced apart such that the first bullet strikes screen A 8 nanoseconds before the second bullet strikes screen B. It would seem unlikely that manipulating the bullet striking screen B changes what happened to the bullet that struck screen A 8 ns earlier, but that is analogous to what happens in the delayed choice quantum eraser experiment except with entangled photons instead of bullets.
Apparently the Copenhagen interpretation doesn't care about the 8 ns difference, but if you set that aside and try to come up with some "real" interpretation using hidden variables or something along those lines, it seems difficult to explain how actions in the present can apparently rewrite what happened in the past.
a reply to: delbertlarson
I don't know if there is such a thing as a magnetic monopole or not, but I agree there's no evidence for them, since we can't count pseudoparticles. However some theorists seem to like the idea of magnetic monopoles and if they ever are discovered then we couldn't cite magnetic dipoles as a special exception. We could also cite other electromagnetic relationships like current flowing through a wire obeying a 1/r relation ship instead of inverse square so maybe other exceptions exist too, but I still think of electromagnetism as fundamentally inverse square phenomenon even though I'm aware of numerous exceptions. I certainly wouldn't say it's fundamentally an inverse cube phenomenon, and I think even you will agree with that.
In the delayed choice quantum eraser experiment, they are definitely interfering with the experiment when they manipulate the entangled partner, no question about that, but the timing is the interesting part of that experiment.
In a classical analogy lets say you fired two "entangled bullets" (there's no such thing but I'm just using this to help think about what is strange about the timing). Lets say one strikes screen A and the other strikes screen B at the same time. Aside from the mystery of how it can happen simultaneously, we could still try to visualize something like hidden variable linkages between the two things that allow manipulating one bullet to affect the outcome of the other bullet's impact on the screen.
Now let's say you fire entangled bullets at two screens spaced apart such that the first bullet strikes screen A 8 nanoseconds before the second bullet strikes screen B. It would seem unlikely that manipulating the bullet striking screen B changes what happened to the bullet that struck screen A 8 ns earlier, but that is analogous to what happens in the delayed choice quantum eraser experiment except with entangled photons instead of bullets.
Apparently the Copenhagen interpretation doesn't care about the 8 ns difference, but if you set that aside and try to come up with some "real" interpretation using hidden variables or something along those lines, it seems difficult to explain how actions in the present can apparently rewrite what happened in the past.
a reply to: delbertlarson
I don't know if there is such a thing as a magnetic monopole or not, but I agree there's no evidence for them, since we can't count pseudoparticles. However some theorists seem to like the idea of magnetic monopoles and if they ever are discovered then we couldn't cite magnetic dipoles as a special exception. We could also cite other electromagnetic relationships like current flowing through a wire obeying a 1/r relation ship instead of inverse square so maybe other exceptions exist too, but I still think of electromagnetism as fundamentally inverse square phenomenon even though I'm aware of numerous exceptions. I certainly wouldn't say it's fundamentally an inverse cube phenomenon, and I think even you will agree with that.
edit on 20181125 by Arbitrageur because: clarification
a reply to: Arbitrageur
Nothing "real" about entanglement as far as I know (but I know little about quantum physics), but it does seem be there.
Have you seen the followup video? Regarding that "rewriting" and what it implies?
www.youtube.com...
Apparently the Copenhagen interpretation doesn't care about the 8 ns difference, but if you set that aside and try to come up with some "real" interpretation using hidden variables or something along those lines, it seems difficult to explain how actions in the present can apparently rewrite what happened in the past.
Nothing "real" about entanglement as far as I know (but I know little about quantum physics), but it does seem be there.
Have you seen the followup video? Regarding that "rewriting" and what it implies?
www.youtube.com...
edit on 11/25/2018 by Phage because: (no reason given)
I watched it. You can use your knowledge to get a free T-shirt!
originally posted by: Phage
I know little about quantum physics...
Have you seen the followup video? Regarding that "rewriting" and what it implies?
I like the way he says lets assume we can bounce photons between the earth and moon 8000 times. Have you seen the power of the laser they aim at the retroreflectors on the moon just to get a small number of photons back?
They fire something 200 quadrillion photons per laser pulse and if they are lucky get 1-3 back, and that's just on the first round trip! It's not looking good for the other 7999 round trips.
But if you can solve that and the other problems, I'm not sure if you can trust him to share his lottery winnings with you, better use it to win the lottery yourself.
a reply to: Arbitrageur
Too late. The winners were announced.
www.youtube.com...
You can use your knowledge to get a free T-shirt!
Too late. The winners were announced.
www.youtube.com...
a reply to: Arbitrageur
I don't get it. You're saying that 1 absorbed photon will create 2 photons. The 2 photons are now 1/2 the energy of the original photon. If that's the case, why don't these 2 photon, which are now following a path up or down, generate 2 photons when it hits the next beam splitter? Following the previous example, the 2 photons created at that point would have 1/4 the energy of the original, or parent photon? If the original photon isn't split and 2 new photons are created, why are the 2 new photons 1/2 the energy of the original?
He doesn't use the word "splits". He says the experiment uses a :"crystal that absorbs an incoming photon and creates two new photons, each with 1/2 the energy of the original." That seems like a pretty good description to me.
I don't get it. You're saying that 1 absorbed photon will create 2 photons. The 2 photons are now 1/2 the energy of the original photon. If that's the case, why don't these 2 photon, which are now following a path up or down, generate 2 photons when it hits the next beam splitter? Following the previous example, the 2 photons created at that point would have 1/4 the energy of the original, or parent photon? If the original photon isn't split and 2 new photons are created, why are the 2 new photons 1/2 the energy of the original?
edit on 25-11-2018 by Phantom423 because: (no reason given)
Unless you can figure out a way to re-write the past....
originally posted by: Phage
Too late. The winners were announced.
www.youtube.com...
It's not the beam splitter that absorbs the photon and emits two new photons with half the energy, it's the BBO crystal, in the blue box seen above, and again they are photons, not protons as the sketch says. This happens before any of the the beam splitters.
originally posted by: Phantom423
I don't get it. You're saying that 1 absorbed photon will create 2 photons. The 2 photons are now 1/2 the energy of the original photon. If that's the case, why don't these 2 photon, which are now following a path up or down, generate 2 photons when it hits the next beam splitter? Following the previous example, the 2 photons created at that point would have 1/4 the energy of the original, or parent photon? If the original photon isn't split and 2 new photons are created, why are the 2 new photons 1/2 the energy of the original?
The beam splitters, identified by the orange arrows in your sketch, send 50% of the photons through, and reflect the other 50%, but the energy levels aren't halved by the beam splitter, they all stay the same. Regular glass reflects something on the order of 4% of photons so the beam splitters have just enough reflective coating added to raise that reflection level to 50%.
I just watched the video and yes he carefully mentions electric force, not mentioning magnetism at all.
originally posted by: delbertlarson
At about the 45:30 point he returns to how gravity relates to other forces, and how gravity relates to other parts of nature, and then remarks that both gravity and the electric force fall off as 1/r^2. At 46:01 he mentions that perhaps gravity and electricity are aspects of the same thing, and discusses this for a few minutes. It is in the sections near 7:12, 37:04, 45:30, and 46:01 that my earlier point is made in this video. My comment now, as it was then, is that dipole forces do not fall off as 1/r^2.
Again as you said he mentioned electric force specifically, and didn't mention electromagnetism or magnetism specifically though I understand electricity and magnetism are sort of like two sides of the same coin and that's how you're making the connection you want to refute, but it seems to me Feyman was very careful to focus on electricity, possibly because he might even know exactly what your objection might be if he didn't.
Why do I return to this point about the dipole force? Because, back in my grad school days many years ago, I pondered what Feynman is pondering, and then I came to realize that the magnetic dipole moment of the electron appears to be every bit as fundamental as its charge. So I don't think we should try to generalize from gravity to all other forces. I suspect that my pondering back then might have been initiated by Feynman.
About the deeper meaning of inverse square, Feynman didn't mention this and I don't know why, but it's always seemed to me to be a simple geometrical relationship. Take an incandescent light bulb for example emitting photons in all directions. Let's say at distance X from the bulb, there are 4 billion photons per square centimeter per second, and at distance 2x there are 1 billion photons per square centimeter per second. That's because at twice the distance they are spread over an area which is 2x2 as great or 4 times as great, essentially following the relationship of the surface area of a sphere to its radius.
It seems to me this would be the likely underlying geometry which might give electric charge and gravity the same inverse square law since let's say if gravitons exist, those force carriers would follow the same geometry of spreading out as the photons, as would the photon force carriers of a charged particle's electric field. So even if gravity and electricity have no other relationship, it at least seems possible that they both have inverse square because of similar geometry, which could also correspond to other phenomena which might exhibit similar geometry, like the distribution of photons coming from an incandescent bulb.
You read a lot more into that than I did, I just saw students walking into and out of the lecture hall. The bells are in a tower that's a prominent feature on the Cornell campus. Cornell is quite proud of them and chimesmasters even play concerts on the chimes. If you watch or download a video by Fabiola Gianotti about the LHC Atlas experiment, or any number of other videos at that Cornell link by other speakers, you'll see the tower with the chimes features on the top banner, so it's the chimes are not ascribing any religious significance to any particular speaker, they appear to just be part of the Cornell campus tradition.
I also wish to comment that the full video has several attributes I find disturbing. The intro has all the markings of worship. Church bells ringing as the buildings are shown, and then "worshipers" are seen heading in for a service, with the title of the talk superimposed on the video. Next, a fawning introduction by Provost Corson, with excerpts I recall from reading Feynman's autobiography. Then the talk. And then at the end, we see applause, followed by the church bells, accompanied by scenes of the worshipers leaving the service, and then the building against the sky. It's a bit much.
Here's the link to the video again.
My favorite part of the video is when two apparently contradictory but still true statements roll off his lips in rapid succession:
Because of our understanding of gravity, we know now why the earth is round, because everything gets pulled together, and we also know why the earth is not round, because it's spinning.
The reason that made me smile is Neil DeGrasse Tyson said something similar and some flat earther edited his comment to make a youtube video about Tyson saying the earth is not round, omitting the context where he also said it was round. I think Eros touched on this earlier but I think it gets into the idea that nature is complex, and that when you start digging into the many complex details of nature, then it no longer seems contradictory to say "the earth is round" and "the earth is not round" in the same breath. Only people who don't understand complexity would say it must be one or the other. It also raises the question physicists must deal with all the time, how do you define your terms? What does it mean for something to be round, and so on. It turns out that billiard balls have specifications for how much they are allowed to deviate from roundness and the earth can be compared to those same standards to determine if it's more or less round than a billiard ball, or at least the billiard ball specifications, since the billiard balls usually meet or exceed those by a fair margin.
So why did Neil DeGrasse Tyson say the earth was pear shaped?
This argument is used often by flat Earthers to claim that the scientific community is lying...In reality, Tyson was describing the fact that just as the earth is technically not a sphere, it is also not technically an oblate spheroid either.
edit on 20181126 by Arbitrageur because: clarification
After I slept on this idea and thought more about it, I'm not sure this is right that the magnetic dipole is as fundamental as charge. Maybe if there were magnetic monopoles it would be, but part of your argument is that there's no such thing as magnetic monopoles, and assuming you're right about that, then you can't have any kind of dipole without electric charge. The electron wouldn't have a magnetic dipole moment if it didn't have charge, would it? Maybe charge is what's really fundamental, if you're right that there are no magnetic monopoles, which could very well be the case.
originally posted by: delbertlarson
Why do I return to this point about the dipole force? Because, back in my grad school days many years ago, I pondered what Feynman is pondering, and then I came to realize that the magnetic dipole moment of the electron appears to be every bit as fundamental as its charge.
Charge seems more fundamental in this sense: you can have charge without a magnetic field, but can you have a magnetic field without charge, except maybe in a photon? The discovery of a magnetic monopole could change that, however I also tend to think there probably aren't any magnetic monopoles, quasiparticles aside.
edit on 20181126 by Arbitrageur because: clarification
a reply to: Arbitrageur
All you need for the magnetic dipole moment is a current. We know that particles have an angular momentum (spin) which is related to the magnetic moment. So I'd argue that the magnetic moment is the result of spin and charge and not a fundamental property.
All you need for the magnetic dipole moment is a current. We know that particles have an angular momentum (spin) which is related to the magnetic moment. So I'd argue that the magnetic moment is the result of spin and charge and not a fundamental property.
a reply to: Arbitrageur
Note - I am falling behind. (That darn day job.) What follows are comments from earlier. I will need to take more time for any response concerning the fundamental nature of the magnetic dipole. I've also been working on a quantum eraser response. It all takes time.
Thanks for the education. I did not know of the Cornell campus tradition. It adds some perspective to things for me.
Clearly, Feynman knew about the magnetic dipole. My point for three or four decades has been that it is unlikely that E&M and gravity are specific instances of the same underlying law of nature. If so, gravity would have a magnetic-like component in addition to its electric-like one, and moving gravitational objects should show that.
I do agree that 1/r^2 has a geometric origin, but I think it comes from something other than force-carrier emission. Indeed, if you look at my article on The Aether, you will see my earlier proposal of where the electric 1/r^2 comes from. In an incompressible aether, if you add a small sphere of aether to the ambient aether, the ambient aether will be pushed out radially. Each concentric spherical shell of pushed-out aether must have the same amount of aether as the source (a result of incompressibility). So we get Q = 4pi*r^2*dr*rho, where Q is the amount of aether in the small sphere, r the distance to an arbitrary surrounding shell (and hence 4pi*r^2 the surface area of the shell), rho the aether density, and dr the thickness of the shell. So dr, the distance each shell surface moves, falls off as 1/r^2. The electric field is proportional to the separation between the two types of aether, so if one type of aether is displaced in this way, and the other not, you get the observed electric field law. Simple as can be.
To derive the Lorentz Force Law, the incompressibility axiom will be changed in my upcoming work, but in a way that a similar argument to the above still applies. (In the new axiom, a charge will push out one type of aether and pull in the other.)
Of course, Einstein proposed a geometric origin for gravity (mass-energy curves space) which is considerably different than my simple ball-pushes-aether-radially-outward idea for the static electric field. And also of course, in the appropriate limit general relativity leads to the Newtonian limit (click here for a derivation ) which of course has a 1/r^2 force drop off. But Einstein's geometric origin for gravity is quite different than my geometric aetherial approach to deriving the electric field.
THE CONJECTURE
I believe that gravity might also come out of a geometric relationship from within an aetherial medium, but with a different underlying cause than the relative displacements between the two aether components that leads to the static electric field. As a pure conjecture, a guess might be that mass-energy pinches the aether to change the density of both types of aether. Such a pinch could also lead to a geometric 1/r^2 fall off of an attractive force, to first order. The key question is whether such a density change can lead to similar Riemannian geometry to that which Einstein obtained from a relativity principle. Do you know if it can?
Note - I am falling behind. (That darn day job.) What follows are comments from earlier. I will need to take more time for any response concerning the fundamental nature of the magnetic dipole. I've also been working on a quantum eraser response. It all takes time.
the chimes are not ascribing any religious significance to any particular speaker, they appear to just be part of the Cornell campus tradition.
Thanks for the education. I did not know of the Cornell campus tradition. It adds some perspective to things for me.
Again as you said he mentioned electric force specifically, and didn't mention electromagnetism or magnetism specifically though I understand electricity and magnetism are sort of like two sides of the same coin and that's how you're making the connection you want to refute, but it seems to me Feyman was very careful to focus on electricity, possibly because he might even know exactly what your objection might be if he didn't.
Clearly, Feynman knew about the magnetic dipole. My point for three or four decades has been that it is unlikely that E&M and gravity are specific instances of the same underlying law of nature. If so, gravity would have a magnetic-like component in addition to its electric-like one, and moving gravitational objects should show that.
About the deeper meaning of inverse square, Feynman didn't mention this and I don't know why, but it's always seemed to me to be a simple geometrical relationship. Take an incandescent light bulb for example emitting photons in all directions. Let's say at distance X from the bulb, there are 4 billion photons per square centimeter per second, and at distance 2x there are 1 billion photons per square centimeter per second. That's because at twice the distance they are spread over an area which is 2x2 as great or 4 times as great, essentially following the relationship of the surface area of a sphere to its radius.
It seems to me this would be the likely underlying geometry which might give electric charge and gravity the same inverse square law since let's say if gravitons exist, those force carriers would follow the same geometry of spreading out as the photons, as would the photon force carriers of a charged particle's electric field.
I do agree that 1/r^2 has a geometric origin, but I think it comes from something other than force-carrier emission. Indeed, if you look at my article on The Aether, you will see my earlier proposal of where the electric 1/r^2 comes from. In an incompressible aether, if you add a small sphere of aether to the ambient aether, the ambient aether will be pushed out radially. Each concentric spherical shell of pushed-out aether must have the same amount of aether as the source (a result of incompressibility). So we get Q = 4pi*r^2*dr*rho, where Q is the amount of aether in the small sphere, r the distance to an arbitrary surrounding shell (and hence 4pi*r^2 the surface area of the shell), rho the aether density, and dr the thickness of the shell. So dr, the distance each shell surface moves, falls off as 1/r^2. The electric field is proportional to the separation between the two types of aether, so if one type of aether is displaced in this way, and the other not, you get the observed electric field law. Simple as can be.
To derive the Lorentz Force Law, the incompressibility axiom will be changed in my upcoming work, but in a way that a similar argument to the above still applies. (In the new axiom, a charge will push out one type of aether and pull in the other.)
Of course, Einstein proposed a geometric origin for gravity (mass-energy curves space) which is considerably different than my simple ball-pushes-aether-radially-outward idea for the static electric field. And also of course, in the appropriate limit general relativity leads to the Newtonian limit (click here for a derivation ) which of course has a 1/r^2 force drop off. But Einstein's geometric origin for gravity is quite different than my geometric aetherial approach to deriving the electric field.
THE CONJECTURE
I believe that gravity might also come out of a geometric relationship from within an aetherial medium, but with a different underlying cause than the relative displacements between the two aether components that leads to the static electric field. As a pure conjecture, a guess might be that mass-energy pinches the aether to change the density of both types of aether. Such a pinch could also lead to a geometric 1/r^2 fall off of an attractive force, to first order. The key question is whether such a density change can lead to similar Riemannian geometry to that which Einstein obtained from a relativity principle. Do you know if it can?
a reply to: Arbitrageur
a reply to: moebius
The reason I thought back in graduate school that the electron's magnetic moment was fundamental was largely because of the g-factor of about 2. I recall that the straight-forward derivation resulted in a magnetic moment that is very close to half of what is actually seen, so it needed to be multiplied by the "g-factor". No one back then knew why there was that g-factor of 2. So I then came to the conclusion that it must be some fundamental aspect of nature, and in turn, the electron's magnetic moment was fundamental as well. Do you know of any advance in more recent years that describes where the factor of 2 comes from? (I recall that g-2 is explained by QED, but what about the 2 part of it?)
If we consider the magnetic moment to be fundamental, that plays into the issue of E&M being different than gravity. However, my comments about Einsteinian gravity being different geometrically than E&M, and gravity not having a "magnetic-like" counterpart, also lead me to believe that gravity and E&M are not two aspects of the same thing. And that is why I have thought for a long time that Feynman was heading in the wrong direction when he speculated that they were possibly two aspects of the same thing.
I'm not sure this is right that the magnetic dipole is as fundamental as charge.
a reply to: moebius
All you need for the magnetic dipole moment is a current. We know that particles have an angular momentum (spin) which is related to the magnetic moment. So I'd argue that the magnetic moment is the result of spin and charge and not a fundamental property.
The reason I thought back in graduate school that the electron's magnetic moment was fundamental was largely because of the g-factor of about 2. I recall that the straight-forward derivation resulted in a magnetic moment that is very close to half of what is actually seen, so it needed to be multiplied by the "g-factor". No one back then knew why there was that g-factor of 2. So I then came to the conclusion that it must be some fundamental aspect of nature, and in turn, the electron's magnetic moment was fundamental as well. Do you know of any advance in more recent years that describes where the factor of 2 comes from? (I recall that g-2 is explained by QED, but what about the 2 part of it?)
If we consider the magnetic moment to be fundamental, that plays into the issue of E&M being different than gravity. However, my comments about Einsteinian gravity being different geometrically than E&M, and gravity not having a "magnetic-like" counterpart, also lead me to believe that gravity and E&M are not two aspects of the same thing. And that is why I have thought for a long time that Feynman was heading in the wrong direction when he speculated that they were possibly two aspects of the same thing.
All I know about the hypothetical aether if such may exist is that it can't have the properties searched for in experiments by Michelson-Morley and others which found a null result. I tend to agree that those experiments don't rule out some other kind of aether with other properties as long as they don't contradict observation, but I can't say I've given as much thought to theorizing about a hypothetical aether as you have so I don't know the answer.
originally posted by: delbertlarson
As a pure conjecture, a guess might be that mass-energy pinches the aether to change the density of both types of aether. Such a pinch could also lead to a geometric 1/r^2 fall off of an attractive force, to first order. The key question is whether such a density change can lead to similar Riemannian geometry to that which Einstein obtained from a relativity principle. Do you know if it can?
This paper claims to have the answer to where that factor of 2 comes from, but I don't know if it's right.
originally posted by: delbertlarson
The reason I thought back in graduate school that the electron's magnetic moment was fundamental was largely because of the g-factor of about 2. I recall that the straight-forward derivation resulted in a magnetic moment that is very close to half of what is actually seen, so it needed to be multiplied by the "g-factor". No one back then knew why there was that g-factor of 2. So I then came to the conclusion that it must be some fundamental aspect of nature, and in turn, the electron's magnetic moment was fundamental as well. Do you know of any advance in more recent years that describes where the factor of 2 comes from? (I recall that g-2 is explained by QED, but what about the 2 part of it?)
The Real Reason Why the Electron’s Bare g-Factor Is 2 Times Classical
By examining the electromagnetic wave nature of the electron, it is possible to show a simple reason why its bare g-factor must be 2, without resorting to superluminal velocities or dismissing it as mystically intrinsic. A simple charged electromagnetic wave loop (CEWL) model of the electron that maintains the same electromagnetic wave nature as the high-energy photons from which electron-positron pairs form, will have exactly half of its energy in the form of magnetic energy who’s field lines are perpendicular to the direction of the charge rotation, which leads to the conclusion that only half of the electron’s electromagnetic mass is rotational mass, from which it is easy to calculate a bare g-factor of 2 using Feynman’s equation for the electron’s g-factor.
Feynman was always very clear to say that nobody has ever shown the relation between gravity electric fields, other than a similar inverse square relationship, but he's certainly not the only one to think of the possibility of a theory of everything which would relate all known forces in a single theory, which is sort of an unsolved holy grail in physics. I don't know how he thought about this but at the very least I think he was just trying to get his students to think about possibilities, not to draw any conclusions when he was emphatic that evidence for such unification was lacking. A popular idea now seems to be that a theory of everything might relate them at high energies as shown here but this is, I'm not sure whether to call it hypothetical or speculative, but it's certainly unconfirmed since these energies are beyond experimental reach.
If we consider the magnetic moment to be fundamental, that plays into the issue of E&M being different than gravity. However, my comments about Einsteinian gravity being different geometrically than E&M, and gravity not having a "magnetic-like" counterpart, also lead me to believe that gravity and E&M are not two aspects of the same thing. And that is why I have thought for a long time that Feynman was heading in the wrong direction when he speculated that they were possibly two aspects of the same thing.
hyperphysics.phy-astr.gsu.edu...
Even if true it seems like a rather distant connection of you have to go back to the Planck time at the beginning of the universe to show a relationship. The electromagnetic and weak forces unifying into the electroweak force at lower energies has been confirmed, and I'm not really sure of the status of unifying the electroweak and strong forces (grand unification) except that confidence about that seems to be lower than for the electroweak unification
Back to the Solar observatory where you thought people working there might talk about what really happened (they haven't as far as I know), so far this is the only hypothesis I've seen which speculates about possible reasons why they may not be talking. It seems plausible, though that doesn't mean it's right. Some things are confirmed fact though, like the quote I pulled from the article, which I think could be a big clue, as does the author of this article.
www.thedrive.com...
The National Solar Observatory's site enjoys a wide and largely unobstructed view of both the U.S. Air Force's Holloman Air Force Base and the U.S. Army's White Sands Missile Range, both of which regularly host a very wide array of U.S. military research and development programs.
edit on 20181129 by Arbitrageur because: clarification
a reply to: Arbitrageur
Some comments on the quantum eraser paper from 1999. There are pictures of the apparatus above on this thread, so please refer to them.
1) From Reference - arxiv.org... in the abstract:
The event may not actually be "after", as discussed below.
2) From Reference - arxiv.org... first paragraph:
No. Momentum is both magnitude and direction. If we precisely learn the position of a photon by passing a laser beam through a narrow slit, some momenta (those that are more central) are more likely than others (those of larger angle). Now some of this critique revolves around what we define as "precise", but I wish to mention this issue.
3) From Reference - arxiv.org... page 1, right column, near the top:
A better description, I would submit, is that all atoms within the illumination of both slits have a probability of being excited by the laser pulse. Some of the laser light gets absorbed by the wall containing the two slits. The remaining light gives a probability of excitation to every atom that the light hits. The probability distribution manifests as a wave function of the excitation.
4) From reference - arxiv.org... page 1, right column, near the top:
And from reference - arxiv.org... page 2, left column, about 3/5ths down:
Rather than "either" I believe the paper should say "either or both". If emission occurs from only A or B, there will be no interference, since the BBO crystal is beyond the slits. To get interference, both A and B must contribute to the wave function.
5) From reference - arxiv.org... page 1, much of the right column:
The discussion says that the photons will have a 50% chance of going through various mirrors. More correctly, I believe, the situation is that 50% of each photon goes in each direction through each mirror. Prior to collapse, the wave function will exist in all paths simultaneously. Once the collapse occurs, the photon will localize to the point of collapse.
6) From reference - arxiv.org... page 2, left column, near the top:
It is unclear to me how the “joint detection” works. If the count rate is low enough, then it is easy to see. Perhaps that is the case.
7) From reference - arxiv.org... page2, left column, near bottom:
D4 does not appear in Figure 2. Further there are results for D1, D2 and D3 given, but not D4. Now there is no particular reason that you'd need a D4, so at first I thought perhaps there was none. The apparatus could have worked just fine without one, just as shown in Figure 2, but the results may have been changed. Or perhaps there was a D4, but it just isn't shown in Figure 2. Later in the paper D4 is referred to several times. Also, the results appear to me to be consistent with a D4. So I came to the conclusion that there is a D4, and it just isn't shown in Figure 2.
8) From reference - arxiv.org... page2, right column, near top:
One issue for whether or not the erasure is delayed is the response time of the detectors, true. But the length of the photons is also involved. I will return to this issue in the analysis which comes next.
9) A realist, physical, analysis of the 1999 Quantum Eraser paper.
As for what is happening, I believe that the critical issues are these: 1)How long is the photon? and 2) Must the entire photon pass before a collapse occurs? While the signal photon will record first, it is still possible that the leading edge of the idler photon is already at its detectors prior to the time the tail of the signal photon finishes its interaction at D0. As long as the full collapse only occurs after the entire quanta has arrived, this criteria would enable the overall wave function to interact with all five detectors and the results can be understood.
So how long is a photon? In the first result of a google search we see that I.V.Drozdov and A.A.Stahlhofen argue that it is one-half of a wavelength long. I.V.Drozdov and A.A.Stahlhofen assign delta-E * tau = h/2, and define delta-E as the energy of the photon to arrive at their result. However, another approach is to assign delta-E as the uncertainty in the energy, or energy spread, and not the full energy, leading to a much longer photon. And the uncertainty in the energy relates to the line width when there are many photons acting together, like in the Argon laser illuminating the 1999 Quantum Eraser. Further, the line width corresponds to the coherence length.
As long as the length of the photon is determined by its coherence length, and the entire photon must arrive at the detector before an event is recorded, then the 1999 Quantum Eraser experimental results can be understood via instantaneous collapse of the extended wave function.
Note that the above theoretical footing suggests an experiment wherein the difference between the idler and signal flight paths is greater than the coherence length, as in that case no effect between the idler and signal should be observed. (Although that may already be expected, after all, we would then be beyond a point where there is coherence.)
Some comments on the quantum eraser paper from 1999. There are pictures of the apparatus above on this thread, so please refer to them.
1) From Reference - arxiv.org... in the abstract:
The which-path or both-path information of a quantum can be erased or marked by its entangled twin even after the registration of the quantum.
The event may not actually be "after", as discussed below.
2) From Reference - arxiv.org... first paragraph:
We say that the quantum observables “position” and “momentum” are “complementary” because the precise knowledge of the position (momentum) implies that all possible outcomes of measuring the momentum (position) are equally probable.
No. Momentum is both magnitude and direction. If we precisely learn the position of a photon by passing a laser beam through a narrow slit, some momenta (those that are more central) are more likely than others (those of larger angle). Now some of this critique revolves around what we define as "precise", but I wish to mention this issue.
3) From Reference - arxiv.org... page 1, right column, near the top:
Two atoms labeled by A and B are excited by a laser pulse.
A better description, I would submit, is that all atoms within the illumination of both slits have a probability of being excited by the laser pulse. Some of the laser light gets absorbed by the wall containing the two slits. The remaining light gives a probability of excitation to every atom that the light hits. The probability distribution manifests as a wave function of the excitation.
4) From reference - arxiv.org... page 1, right column, near the top:
Two atoms labeled by A and B are excited by a laser pulse. A pair of entangled photons, photon 1 and photon 2, is then emitted from either atom A or atom B by atomic cascade decay.
And from reference - arxiv.org... page 2, left column, about 3/5ths down:
A pair of 702.2nm orthogonally polarized signal-idler photon is generated either from A or B region.
Rather than "either" I believe the paper should say "either or both". If emission occurs from only A or B, there will be no interference, since the BBO crystal is beyond the slits. To get interference, both A and B must contribute to the wave function.
5) From reference - arxiv.org... page 1, much of the right column:
The discussion says that the photons will have a 50% chance of going through various mirrors. More correctly, I believe, the situation is that 50% of each photon goes in each direction through each mirror. Prior to collapse, the wave function will exist in all paths simultaneously. Once the collapse occurs, the photon will localize to the point of collapse.
6) From reference - arxiv.org... page 2, left column, near the top:
It is easy to see these “joint detection” events must have resulted from the same photon pair.
It is unclear to me how the “joint detection” works. If the count rate is low enough, then it is easy to see. Perhaps that is the case.
7) From reference - arxiv.org... page2, left column, near bottom:
The triggering of detectors D3 and D4 provide which-path information of the idle
D4 does not appear in Figure 2. Further there are results for D1, D2 and D3 given, but not D4. Now there is no particular reason that you'd need a D4, so at first I thought perhaps there was none. The apparatus could have worked just fine without one, just as shown in Figure 2, but the results may have been changed. Or perhaps there was a D4, but it just isn't shown in Figure 2. Later in the paper D4 is referred to several times. Also, the results appear to me to be consistent with a D4. So I came to the conclusion that there is a D4, and it just isn't shown in Figure 2.
8) From reference - arxiv.org... page2, right column, near top:
Compared to the 1ns response time of the detectors, 2.5 m delay is good enough for a “delayed erasure”.
One issue for whether or not the erasure is delayed is the response time of the detectors, true. But the length of the photons is also involved. I will return to this issue in the analysis which comes next.
9) A realist, physical, analysis of the 1999 Quantum Eraser paper.
As for what is happening, I believe that the critical issues are these: 1)How long is the photon? and 2) Must the entire photon pass before a collapse occurs? While the signal photon will record first, it is still possible that the leading edge of the idler photon is already at its detectors prior to the time the tail of the signal photon finishes its interaction at D0. As long as the full collapse only occurs after the entire quanta has arrived, this criteria would enable the overall wave function to interact with all five detectors and the results can be understood.
So how long is a photon? In the first result of a google search we see that I.V.Drozdov and A.A.Stahlhofen argue that it is one-half of a wavelength long. I.V.Drozdov and A.A.Stahlhofen assign delta-E * tau = h/2, and define delta-E as the energy of the photon to arrive at their result. However, another approach is to assign delta-E as the uncertainty in the energy, or energy spread, and not the full energy, leading to a much longer photon. And the uncertainty in the energy relates to the line width when there are many photons acting together, like in the Argon laser illuminating the 1999 Quantum Eraser. Further, the line width corresponds to the coherence length.
As long as the length of the photon is determined by its coherence length, and the entire photon must arrive at the detector before an event is recorded, then the 1999 Quantum Eraser experimental results can be understood via instantaneous collapse of the extended wave function.
Note that the above theoretical footing suggests an experiment wherein the difference between the idler and signal flight paths is greater than the coherence length, as in that case no effect between the idler and signal should be observed. (Although that may already be expected, after all, we would then be beyond a point where there is coherence.)
edit on 1-12-2018 by delbertlarson because: clarification
edit on 1-12-2018 by delbertlarson because: addjtjk a]][[[
I understand why the experiment may be confusing to some people, but I don't understand how you can not understand the clear explanation in the paper discussing an experiment proposed in 1982, represented in figure 1, and the actual experiment performed in 1999 represented in figure 2, which does not refer to "atoms" like the proposed experiment. Just read the caption of figure 2 which refers to "two regions A and B" (as you yourself note below) so you're picking nits with things they didn't even say about their experiment.
originally posted by: delbertlarson
3) From Reference - arxiv.org... page 1, right column, near the top:
Two atoms labeled by A and B are excited by a laser pulse.
A better description, I would submit, is that all atoms within the illumination of both slits have a probability of being excited by the laser pulse. Some of the laser light gets absorbed by the wall containing the two slits. The remaining light gives a probability of excitation to every atom that the light hits. The probability distribution manifests as a wave function of the excitation.
You don't appear to have understand these simple descriptions of the figures:
4) From reference - arxiv.org... page 1, right column, near the top:
Two atoms labeled by A and B are excited by a laser pulse. A pair of entangled photons, photon 1 and photon 2, is then emitted from either atom A or atom B by atomic cascade decay.
And from reference - arxiv.org... page 2, left column, about 3/5ths down:
A pair of 702.2nm orthogonally polarized signal-idler photon is generated either from A or B region.
Rather than "either" I believe the paper should say "either or both". If emission occurs from only A or B, there will be no interference, since the BBO crystal is beyond the slits. To get interference, both A and B must contribute to the wave function.
"FIG. 1. A proposed quantum eraser experiment...."
"FIG. 2. Schematic of the experimental setup...."
Those captions seem crystal clear that figure 1 is a reference to the proposed experiment, and figure 2 relates to the actual experiment performed in 1999, and if you don't understand this simple concept that the performed experiment may have slight differences from the "thought experiment" proposed 17 years earlier, I don't see how you're going to understand the complexities of the experiment which are more technical and more difficult to grasp. I'm not sure I can explain the experiment better than the paper, probably not, but if you collect all the signal photons and look for an interference pattern, there isn't one. This was explained in the follow up video Phage posted above, did you watch that? The quantum eraser segment starts at 4 minutes in the video; maybe watching that will help, maybe not. Phage also posted the a link to the previous video which asked the question answered here:
www.abovetopsecret.com...
That screenshot is from 5 minutes 12 seconds in the video, with the red dots on the screen showing there is no visible interference pattern.
The first post on page 379 answers a question about the experiment and references a typical SPDC rate in the quoted article as "the probability of one photon splitting is normally just one in a billion, making the probability of it happening twice in succession one in a billion billion. Experimentally, this has been too small to contemplate." So that should have given you some idea of how frequently the SPDC process occurs if you had been reading the thread and following posts about the experiment.
6) From reference - arxiv.org... page 2, left column, near the top:
It is unclear to me how the “joint detection” works. If the count rate is low enough, then it is easy to see. Perhaps that is the case.
Again it seems it's not just the complexities of the experiment you don't follow, it's the simple first sentence of the captions for the two figures. I really don't understand why you find those confusing.
7) From reference - arxiv.org... page2, left column, near bottom:
The triggering of detectors D3 and D4 provide which-path information of the idle
D4 does not appear in Figure 2. Further there are results for D1, D2 and D3 given, but not D4. Now there is no particular reason that you'd need a D4, so at first I thought perhaps there was none. The apparatus could have worked just fine without one, just as shown in Figure 2, but the results may have been changed. Or perhaps there was a D4, but it just isn't shown in Figure 2. Later in the paper D4 is referred to several times. Also, the results appear to me to be consistent with a D4. So I came to the conclusion that there is a D4, and it just isn't shown in Figure 2.
I don't think this line of questioning will bear any fruit but you are of course free to pursue it if you can ever figure out the experiment but I think you still don't understand it, when you say the authors of the paper don't understand their own experiment when they say "A pair of 702.2nm orthogonally polarized signal-idler photon is generated either from A or B region." You suggest they are wrong about that because that wouldn't result in an interference pattern. I suggest they are right and it's you that don't understand their experiment, since they don't get an interference pattern collecting all the photons (see the video screenshot), they have to extract it using the coincidence circuit.
8) From reference - arxiv.org... page2, right column, near top:
One issue for whether or not the erasure is delayed is the response time of the detectors, true. But the length of the photons is also involved. I will return to this issue in the analysis which comes next.
9) A realist, physical, analysis of the 1999 Quantum Eraser paper.
As for what is happening, I believe that the critical issues are these: 1)How long is the photon? and 2) Must the entire photon pass before a collapse occurs?
The reason I don't think pursuing photon length will be a fruitful exercise is that quantum theory says you can move the apparatus further apart and the result will persist, so no matter how long you calculate the photon to be (did you calculate a photon length? What did you come up with?), just make the experiment longer; it should not change the result except that instead of an 8ns delay there will be some longer delay and I know of no theoretical limit to how large that can be, though obviously there are practical experimental limits.
edit on 2018125 by Arbitrageur because: clarification
a reply to: Arbitrageur
Last time your criticism of my post had some merit, although I will likely comment on that soon. This time though I believe your criticism was way off. I studied the paper for quite some time and it was of course very clear to me that Figure 1 was from a 1982 proposal and Figure 2 represented the 1999 experiment. It is also clear that within the paper itself the description of Figure 1 begins on page 1, right hand side, starting with the paragraph "One proposed quantum eraser" and going through to the end of that paragraph which ends on page 2. And then, at the start of the next paragraph "We wish to report" the paper begins to report on the actual experiment. Something in what I wrote must have led you to believe I didn't understand these rather basic and obvious facts; I have no idea what caused you to be so far off in your conclusion, and without knowing I can't really respond effectively.
I have prepared over 200 reviews on fundamental physics papers, and what I presented in my previous post was what I would have done for an initial review. I always try to assist the authors to improve the clarity of their works, and that was the reason for many of the above points. Nitpicking can be a good thing during a review, as it improves the quality of the work. About half of authors (those who wished to improve their work) really liked my efforts and would thank me; others were less welcoming of criticism. On occasions, authors would point out why my comments were wrong, and that too is part of the process. Normally though, when I was wrong, additional clarity was helpful in the paper itself, and that too improved the paper.
In addition to serving as review comments, the previous post illustrates my thinking on this matter.
As a guess as to why you were so off on my understanding, one possibility is that you are missing my main point, which is this: Even though the detector D0 only shows an interference pattern if the coincidence is used to decrypt it, it is still true that to even get that interference one must have some portion of the wave function that emanates from two coupled sources - i.e., the wave function must leave both and A and B, at least for some of the events. This is true both for the theorized Fig 1 and for the experimental Fig 2. It can't be that the photon leaves just A or B, it must leave A and/or B. That is the key assertion I am making.
The paper uses the earlier 1982 theory as a simpler introduction into the 1999 experiment, and so its description should certainly also be fair game for review comments. And in both the 1982 and 1999 discussions, the authors neglect to mention that an important case is when the wave function emanates from both regions.
After you referred me back to the post at the top of page 379 I now see how the coincidence works, thank you. (It was what I surmised - a low enough count rate, but I didn't see that mentioned in the paper either.) The reason I missed the quote at the top of page 379 was that the discussion there was about splitting of a photon, and I didn't see the relevance in delving into that subtopic, as that is not a very accurate description of what really happens (in my opinion) so I just skimmed through that discussion.
The other issue is that at the 1:04 point of this video that you point me to it says that the real experiment didn't use D4 (which the video calls detector B). On that issue, can we trust the video? The paragraph in the actual paper discussing Fig 2 (which starts with "We wish to report") mentions D4 several times, and in such a way that it leads me to conclude there was indeed a D4. So shouldn't we trust the actual publication on this point? On the other hand, Fig 2 of the actual publication shows no D4. My guess is it was left off of the figure to avoid clutter, although nowhere in the paper do I see it mentioned that they did this. (If you look at Fig. 2 you can see that the lines leading to where D4 would be would cross over the lines leading to D0, and cross over the identification of f, so clarity is improved by leaving it out of the diagram, even if it was there.) Now perhaps there was no D4, and the video author got that information from the authors, but in that case the paragraph which starts with "We wish to report" is misleading with respect to D4. Or perhaps the video author just used the figure to infer there was no D4. Do you know if there was a D4? In any event, as I said in my prior post, there is no particular reason that you'd need a D4, it is just something that should have been clearer in the paper. As it stands, the paper is quite confusing on this point.
I don't know how long the photons were in the experiment. I saw no indication of the line width of the exciting Argon laser, or if anything was done to affect the line width. As you likely know, sometimes coherence length can be kilometers, other times much less. The main point is that I think I can see how the results could be obtained via an instantaneous collapse of a wave function that exists throughout the apparatus provided that the photons are long enough. On the other hand, I am still working through my thoughts about what would happen if the length difference exceeds the coherence length. This is an interesting question.
Last time your criticism of my post had some merit, although I will likely comment on that soon. This time though I believe your criticism was way off. I studied the paper for quite some time and it was of course very clear to me that Figure 1 was from a 1982 proposal and Figure 2 represented the 1999 experiment. It is also clear that within the paper itself the description of Figure 1 begins on page 1, right hand side, starting with the paragraph "One proposed quantum eraser" and going through to the end of that paragraph which ends on page 2. And then, at the start of the next paragraph "We wish to report" the paper begins to report on the actual experiment. Something in what I wrote must have led you to believe I didn't understand these rather basic and obvious facts; I have no idea what caused you to be so far off in your conclusion, and without knowing I can't really respond effectively.
I have prepared over 200 reviews on fundamental physics papers, and what I presented in my previous post was what I would have done for an initial review. I always try to assist the authors to improve the clarity of their works, and that was the reason for many of the above points. Nitpicking can be a good thing during a review, as it improves the quality of the work. About half of authors (those who wished to improve their work) really liked my efforts and would thank me; others were less welcoming of criticism. On occasions, authors would point out why my comments were wrong, and that too is part of the process. Normally though, when I was wrong, additional clarity was helpful in the paper itself, and that too improved the paper.
In addition to serving as review comments, the previous post illustrates my thinking on this matter.
As a guess as to why you were so off on my understanding, one possibility is that you are missing my main point, which is this: Even though the detector D0 only shows an interference pattern if the coincidence is used to decrypt it, it is still true that to even get that interference one must have some portion of the wave function that emanates from two coupled sources - i.e., the wave function must leave both and A and B, at least for some of the events. This is true both for the theorized Fig 1 and for the experimental Fig 2. It can't be that the photon leaves just A or B, it must leave A and/or B. That is the key assertion I am making.
The paper uses the earlier 1982 theory as a simpler introduction into the 1999 experiment, and so its description should certainly also be fair game for review comments. And in both the 1982 and 1999 discussions, the authors neglect to mention that an important case is when the wave function emanates from both regions.
After you referred me back to the post at the top of page 379 I now see how the coincidence works, thank you. (It was what I surmised - a low enough count rate, but I didn't see that mentioned in the paper either.) The reason I missed the quote at the top of page 379 was that the discussion there was about splitting of a photon, and I didn't see the relevance in delving into that subtopic, as that is not a very accurate description of what really happens (in my opinion) so I just skimmed through that discussion.
The other issue is that at the 1:04 point of this video that you point me to it says that the real experiment didn't use D4 (which the video calls detector B). On that issue, can we trust the video? The paragraph in the actual paper discussing Fig 2 (which starts with "We wish to report") mentions D4 several times, and in such a way that it leads me to conclude there was indeed a D4. So shouldn't we trust the actual publication on this point? On the other hand, Fig 2 of the actual publication shows no D4. My guess is it was left off of the figure to avoid clutter, although nowhere in the paper do I see it mentioned that they did this. (If you look at Fig. 2 you can see that the lines leading to where D4 would be would cross over the lines leading to D0, and cross over the identification of f, so clarity is improved by leaving it out of the diagram, even if it was there.) Now perhaps there was no D4, and the video author got that information from the authors, but in that case the paragraph which starts with "We wish to report" is misleading with respect to D4. Or perhaps the video author just used the figure to infer there was no D4. Do you know if there was a D4? In any event, as I said in my prior post, there is no particular reason that you'd need a D4, it is just something that should have been clearer in the paper. As it stands, the paper is quite confusing on this point.
I don't know how long the photons were in the experiment. I saw no indication of the line width of the exciting Argon laser, or if anything was done to affect the line width. As you likely know, sometimes coherence length can be kilometers, other times much less. The main point is that I think I can see how the results could be obtained via an instantaneous collapse of a wave function that exists throughout the apparatus provided that the photons are long enough. On the other hand, I am still working through my thoughts about what would happen if the length difference exceeds the coherence length. This is an interesting question.
a reply to: Arbitrageur
This post is to catch up on a few things.
We've now discussed why I viewed Feynman's comment differently than you did on that gravity video. I hope you now understand and respect my point of view, even if you still disagree with it. I will now touch base on why I missed your link.
The reason I reflexively went to Wikipedia before I dove into the published paper is that I have developed quite a low opinion of published papers. I remember being at SLAC in a small group when my major professor (the Nobel-nominated David Cline) used as a defense that something appeared in a peer-reviewed journal. I recall it was Richard Taylor (a few years before his Nobel award) who immediately shot back with something like "I don't care about that; 90% of peer reviewed papers are wrong." At that time I was a newly-minted adjunct professor at UCLA and I laughed, but I was surprised at the comment. I wasn't doubting its veracity, I was just surprised to hear someone actually blurt it out. Since then I've come even more to believe it is accurate. I now believe that most published papers aren't even read.
At least Wikipedia gets read by many, and corrections often occur. So I often go there. Now I know Wikipedia gets a lot wrong too. For one thing, they delete my works. But at least there is a real effort there to constantly improve. In the published record you just get whatever can pass through two reviewers, or maybe just one reviewer. And I suspect that often things get through just based on the reputation of the author.
How bad are things right now? Here is one reference. The situation is well known as a reproducibility crisis. Physics still has a better reputation than most fields, but it has a problem too. Everyone writes; few read.
Another plug for Wikipedia is that it is easier to dig deeper. Papers are often rather cryptic, and leave a lot out. References are there, but you can't often just click them. You can easily follow deeper into Wikipedia by clicking on the embedded links, and I did see the link to the second Wikipedia article about the experiment you preferred I comment on. But the second article was less simple, so I focused on the first one in my first response.
So that is why I headed out the way I did. In this case, things were different though. The paper you referenced and which I have now studied and responded to, was submitted to PRL and is quite famous - it has been read by many! Also, as you pointed out, that paper brings in the aspect of timing. The timing took me some time to figure out. So it is good you refocused me back to the PRL.
But notice that from my comments above that I see several things that the paper leaves unclear. The issue of D4 is one of them. In PRL especially many things of importance are left out due to the page limitation.
But whether PRL, other "less esteemed" publications, or Wikipedia, I like what you said to someone, I forgot who, that we should all just use our brains. We should figure things out for ourselves. Relying on anything else is fraught with peril. Just because it is peer-reviewed is not reason to think it is correct. The paper I referred to in my above post on the length of the photon, and the one you refer to on the origin for the factor of 2 in the electron magnetic moment, are both likely wrong in my opinion.
As long as rods shrink and clocks retard as they move through the aether, then Michelson-Morley and similar experiments are explained. This was Lorentz's theory, and his equations are identical to those of Einstein's special relativity. What I am asking you is whether you know if Riemannian geometry has been applied to substances of varying density. That might lead to a different foundation for general relativity's equations. I believe the principle of relativity is not correct physically; but the equations may be correct or close to correct.
On the grand unified theories, and convergence of forces - I always thought that electro-weak unification was simply the fact that once you get to above the mass of the weak bosons, then the mass effect of those particles pales in comparison to the energy, and hence the exchange of a photon or the exchange of a weak boson begins to look similar. I never saw any deep cosmological significance in that. I am of course aware that a unified theory of everything has been a goal of many physicists for almost a century now. But my take is that this is simply something that some people would like nature to be; nature may have other ideas.
I read the article you linked to, and one that was linked within the article. A semi-plausible explanation was given that authorities were concerned that "a suspect" might harm people, so to make them safe they shut down the observatory and a small post office. But as the article and you state, such precautions don't usually involve Black Hawk helicopters, FBI investigations, and keeping things quiet. The other theory, that there was some espionage going on does seem more likely.
Several posts ago you mentioned I should make some friends at CERN and have them take a look at The ABC Preon Model. My hope is that some of them read this thread, or perhaps EROSA433 might be able to pass word along.
I think I am now once again current on this thread. By the way - the aether model is ever closer to a consistent derivation of both Maxwell's equations and the Lorentz force equation. I believe it is mostly in the clean-up phase now, but during clean-up some nasty surprises sometimes turn up.
This post is to catch up on a few things.
We've now discussed why I viewed Feynman's comment differently than you did on that gravity video. I hope you now understand and respect my point of view, even if you still disagree with it. I will now touch base on why I missed your link.
The reason I reflexively went to Wikipedia before I dove into the published paper is that I have developed quite a low opinion of published papers. I remember being at SLAC in a small group when my major professor (the Nobel-nominated David Cline) used as a defense that something appeared in a peer-reviewed journal. I recall it was Richard Taylor (a few years before his Nobel award) who immediately shot back with something like "I don't care about that; 90% of peer reviewed papers are wrong." At that time I was a newly-minted adjunct professor at UCLA and I laughed, but I was surprised at the comment. I wasn't doubting its veracity, I was just surprised to hear someone actually blurt it out. Since then I've come even more to believe it is accurate. I now believe that most published papers aren't even read.
At least Wikipedia gets read by many, and corrections often occur. So I often go there. Now I know Wikipedia gets a lot wrong too. For one thing, they delete my works. But at least there is a real effort there to constantly improve. In the published record you just get whatever can pass through two reviewers, or maybe just one reviewer. And I suspect that often things get through just based on the reputation of the author.
How bad are things right now? Here is one reference. The situation is well known as a reproducibility crisis. Physics still has a better reputation than most fields, but it has a problem too. Everyone writes; few read.
Another plug for Wikipedia is that it is easier to dig deeper. Papers are often rather cryptic, and leave a lot out. References are there, but you can't often just click them. You can easily follow deeper into Wikipedia by clicking on the embedded links, and I did see the link to the second Wikipedia article about the experiment you preferred I comment on. But the second article was less simple, so I focused on the first one in my first response.
So that is why I headed out the way I did. In this case, things were different though. The paper you referenced and which I have now studied and responded to, was submitted to PRL and is quite famous - it has been read by many! Also, as you pointed out, that paper brings in the aspect of timing. The timing took me some time to figure out. So it is good you refocused me back to the PRL.
But notice that from my comments above that I see several things that the paper leaves unclear. The issue of D4 is one of them. In PRL especially many things of importance are left out due to the page limitation.
But whether PRL, other "less esteemed" publications, or Wikipedia, I like what you said to someone, I forgot who, that we should all just use our brains. We should figure things out for ourselves. Relying on anything else is fraught with peril. Just because it is peer-reviewed is not reason to think it is correct. The paper I referred to in my above post on the length of the photon, and the one you refer to on the origin for the factor of 2 in the electron magnetic moment, are both likely wrong in my opinion.
All I know about the hypothetical aether if such may exist is that it can't have the properties searched for in experiments by Michelson-Morley and others which found a null result.
As long as rods shrink and clocks retard as they move through the aether, then Michelson-Morley and similar experiments are explained. This was Lorentz's theory, and his equations are identical to those of Einstein's special relativity. What I am asking you is whether you know if Riemannian geometry has been applied to substances of varying density. That might lead to a different foundation for general relativity's equations. I believe the principle of relativity is not correct physically; but the equations may be correct or close to correct.
A popular idea now seems to be that a theory of everything might relate them at high energies
On the grand unified theories, and convergence of forces - I always thought that electro-weak unification was simply the fact that once you get to above the mass of the weak bosons, then the mass effect of those particles pales in comparison to the energy, and hence the exchange of a photon or the exchange of a weak boson begins to look similar. I never saw any deep cosmological significance in that. I am of course aware that a unified theory of everything has been a goal of many physicists for almost a century now. But my take is that this is simply something that some people would like nature to be; nature may have other ideas.
Back to the Solar observatory where you thought people working there might talk about what really happened (they haven't as far as I know), so far this is the only hypothesis I've seen which speculates about possible reasons why they may not be talking. It seems plausible, though that doesn't mean it's right. Some things are confirmed fact though, like the quote I pulled from the article, which I think could be a big clue, as does the author of this article.
I read the article you linked to, and one that was linked within the article. A semi-plausible explanation was given that authorities were concerned that "a suspect" might harm people, so to make them safe they shut down the observatory and a small post office. But as the article and you state, such precautions don't usually involve Black Hawk helicopters, FBI investigations, and keeping things quiet. The other theory, that there was some espionage going on does seem more likely.
Several posts ago you mentioned I should make some friends at CERN and have them take a look at The ABC Preon Model. My hope is that some of them read this thread, or perhaps EROSA433 might be able to pass word along.
I think I am now once again current on this thread. By the way - the aether model is ever closer to a consistent derivation of both Maxwell's equations and the Lorentz force equation. I believe it is mostly in the clean-up phase now, but during clean-up some nasty surprises sometimes turn up.
a reply to: delbertlarson
If you accept that the SPDC conversion process is a very rare event, and that interference patters were recorded in the experiment, I don't see how you can still think it's happening at A and B. I believe the authors of the papers in both cases are right that the conversion happens at either A or B just as the papers say.
If a photon is "split" by SPDC in region A, that in no way prevents wave functions from still passing through slit B, so you can still get interference patterns, therefore I see no contradiction between what the authors of the papers say and the experimental results, like you apparently do. I suppose we'll have to agree to disagree.
The reason I didn't think you understood the two different references to the proposal in 1982 and the actual experiment in 1999 is because you were taking the time to criticize the way the 1982 thought experiment was being summarized, and those criticisms didn't really seem to apply to the actual experiment. In fact my understanding is that in 1982 when this was proposed, the 1982 technology wasn't quite what was needed for the experiment which may be why it wasn't performed until 1999, though I don't know all the details on the limitations. But if the technology wasn't there yet in 1982, I expect there were numerous differences in the details of the 1999 experiment compared to the 1982 proposal, even if it was conceptually the same or similar.
If you accept that the SPDC conversion process is a very rare event, and that interference patters were recorded in the experiment, I don't see how you can still think it's happening at A and B. I believe the authors of the papers in both cases are right that the conversion happens at either A or B just as the papers say.
If a photon is "split" by SPDC in region A, that in no way prevents wave functions from still passing through slit B, so you can still get interference patterns, therefore I see no contradiction between what the authors of the papers say and the experimental results, like you apparently do. I suppose we'll have to agree to disagree.
The reason I didn't think you understood the two different references to the proposal in 1982 and the actual experiment in 1999 is because you were taking the time to criticize the way the 1982 thought experiment was being summarized, and those criticisms didn't really seem to apply to the actual experiment. In fact my understanding is that in 1982 when this was proposed, the 1982 technology wasn't quite what was needed for the experiment which may be why it wasn't performed until 1999, though I don't know all the details on the limitations. But if the technology wasn't there yet in 1982, I expect there were numerous differences in the details of the 1999 experiment compared to the 1982 proposal, even if it was conceptually the same or similar.
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