Slinkey

Yes, I understand how interference is created. If you recall my thought experiment called for the entangled particles to be sent to separate double slit experiments one of which has a detector on one of the slits to see which slit the particle went through, and the other does not. As I understand it in the DS experiment, if we let a particle pass through the apparatus undetected we reveal its wave behaviour and an interference pattern will build up on the screen. If we detect which slit the particle went through then we don't get an interference pattern. This implies that we have destroyed the wave property of the particle. Agreed? So, if we have a pair of entangled particles, which as I understand it is described by a single wave function, then if we collapse the wave function by detecting which slit the particle passed through in the DS experiment with the detector, will that make the other entangled particle behave like a particle or will it behave like a wave when it passes through its DS experiment without a detector (experiment 2)?

I don't recall saying that it did. I am under the impression that when we measure some property of a particle we collapse its wavefunction. This explains why we don't get interference in the double slit experiment when we look to see which slit it went through. We've asked it to be a particle so we can see where it went, and the wave function collapses. Is this not correct? So if the wave function is describing an entangled state, when it collapses doesn't its collapse result in two particles?

I was under the impression that entangled particles are described by the same wave equation. I always took this to mean that the wave equation describes both particles and that if one particle collapses the wave equation then the collapse happens for the other particle as well. Thus in experiment 2 where we have the detected particle collapsing the wave equation first it will destroy the wave nature of the other particle. But as you have asked if these states are entangled it's made me think I have misunderstood something basic about entanglement.

Apologies if this has been asked before but as this thought experiment doesn't have a title that I'd know of it's hard to search for it to see if it has been asked. We have a pair of entangled particles. They fly apart toward a different experiment each. Particle A is flying towards the classic double slit experiment which reveals the wave nature of light and the classic interference pattern. Particle B is flying towards another double slit experiment but this one has a detector on one of the slits so we can see which slit the particle went through. There are three ways we can perform this experiment. 1. Particle A reaches its experiment first and we get interference. What happens with particle B? Do we get interference or no interference? Would particle A affect how particle B behaves in its experiment? 2. Particle B reaches its experiment first and we get no interference. What happens with particle A? Do we get interference or no interference? Would particle B affect how particle A behaves in its experiment? 3. They reach their respective experiment simultaneously. What happens? Thoughts?

Thanks for the link. Interesting to read the remarks.

Well, looking back on this thread I'm sad to see it fell into bickering. Apologies for my part in that bickering. I got a little frustrated at not getting my point across, and felt I was not being understood. I'd like to reignite this thread in a more congenial manner. We have fundamental disagreement on the existence of black holes, and looking above I could've used a different way of explaining myself to make my point clearer. First though I would like to hear thoughts on this article which made me come back to this thread. http://www.natureworldnews.com/articles/9187/20140925/are-black-holes-mathematically-impossible.htm

Tell it to get lost.

Err, no. It's precisely because of the different reference frames that this argument comes about and even the part you quoted states it. In the reference frame outside the EH an infinite amount of time must pass before we see anyone cross the EH. The other reference frame - falling in - crosses the EH and is obliterated. As the BH evaporates in less than infinite time then the person outside will never see anyone cross the EH. You can argue all you like about the person claimed to be falling in but it can never be observed from outside the EH as Susskind clearly states. Now we have two different histories. 1) we never see anyone cross the EH and the BH evaporates before they can for any observer outside the EH and they survive. 2) someone falls in and is obliterated. Your assumed flippancy of my reply is simply irrelevant. You just don't want to address what is staring you in the face. There's two histories and they cannot be mixed in any way. You can't both fall in and be crushed to death and someone never observe you fall in before the BH evaporates and survive. It seems that you want to ignore reference frames rather than me not understand them. It's the very fact that there are differing reference frames that this paradox is there. There is no known.... is our knowledge complete? No, it isn't. Thus this is an assumption. It's not selective quoting because you, being of a scientific mind, should know that the case is not proven. No, really? /sarcasm. The point I'm making, which you have skillfully evaded, is that a BH of that mass is far smaller than that radius. ie. it could conceivably still be an object that is not a BH because it can conceivably be larger than the required Schwarzchild radius. A BH is not a BH until it reaches that radius. As we have no direct evidence that the object is a Schwarzchild radius then this is an assumption. So what? Concensus does not make fact. Ok, I agree that my description of this is poor. It should be more correctly described as a particle-antiparticle pair being created at the EH with one escaping to infinity and the other not escaping. The energy that was used to create the pair would need to come from the BH in order for it to evaporate in this way. "If you ever did". Nice ad hominem. I've read it. Deal with it. I have no idea. Does that mean I am wrong? No.

I always read the entire reply and choose what I see as the relevant statements. No, that's incorrect. According to Hawking the mass loss of the BH is due to negative energy crossing the EH. If positive energy crosses then it gains weight. In fact I can think of a way round this. The EH does not have a precise location. If it did it would defy Heisenberg Uncertainty. If a virtual particle-antiparticle pair is created within that region then one could appear beneath the horizon and the other above it. If the positive particle is above the horizon then the BH loses mass due to the negative particle forming below it. Thus it can still evaporate. Point of fact is physicists say that you will never see anything cross the EH due to the infinite time dilation, yet they also accept HR. So, their scenario is the one that says the BH will evaporate before anything crosses the EH. So in a way you have pointed out the flaw in their logic as well. In fact the more I think about it, it doesn't matter if photons (or massless particles) do cross the EH. Anything falling towards it cannot cross the EH as it takes an infinite amount of time to do so for any observer above the EH, and the BH exists for a finite time. All this would do is make me change my argument slightly and the main point still remains. Negative energy/mass.

If you are asking do I have an alternative theory, then no I don't, but I do have a question about the article. It states "In fact, recent observations[15] indicate that the radius is no more than 6.25 light-hours, about the diameter of Uranus' orbit." I worked out the Schwarzchild radius for 4.1 million solar masses and it came out 12,109,072,691.52m, or 40.39 light seconds (feel free to check that), so if the mass is not confined within that radius it isn't a BH. Agreed? 6.25 light hours is substantially larger than 40.39 light seconds. So, you tell me. Are you sure there's a BH there? Anywhere outside the EH. I thought that would be obvious. Edit: Didn't answering the "how" bit. I'm looking through a McDonalds straw because it's fun. Feel free to answer my question from post 129.

You accept Hawking radiation, yes? You have already stated that you will never see Alice cross the EH due to the infinite time dilation. BHs evaporate due to HR. As you will never see Alice cross the EH, when the BH has evaporated, where is Alice? I'll have to re-listen to the audio book and find the part.

Hawking radiation. He says it quite early on. I have the audio book so don't have a page number.

Chris, I'm inclined to think they don't exist at all.

The event of falling toward the EH is outside the EH and is in principle observable by anyone outside the EH. And you also accept that BHs evaporate, yes? So if you never see Alice cross the EH and the BH evaporates then on which side of the EH was/is Alice? It's not a fact. It's a conjecture that has never been evidenced except by math that is known to be incomplete. I suggest you read Leonard Susskind's "The Black Hole War" because he disagrees with you. In fact the only way he can reconcile it is by invoking "black hole complementarity" in the same vein as particle-wave complementarity. Actually this is still hotly debated. So what you're arguing is that the wavelength of a photon can be longer than the photon itself? So we have a wavelength of 1 meter and you are saying the photon would not actually be 1 meter long? Please explain that one to me. An infinite wavelength would have a non-zero frequency. Period.

A zero frequency does not equal an infinite wavelength. Zero frequency equals zero energy and zero wavelength. So nothing passes the EH. As a photon moves toward an EH it's wavelength tends towards infinity. No, at infinite wavelength you have an undefined but non-zero frequency. At zero frequency you simply have nothing. Tunneling occurs when barriers get so small that their own wave properties come into play and aren't barriers in the classical sense. At quantum dimensions "barriers" is not a meaningful term. This is all moot anyway because you don't see photons unless they hit your retina or equipment and this whole discussion is based upon an entirely ambiguous point which I really should've known better than to discuss. So you want to argue that the size of a photon has nothing to do with its wavelength? You want to think of a photon as a point particle that has a wavelength that is longer than a point? As we are talking about an unmeasured photon it is in a super-position. ie. it is completely uncertain and its size could be anything from planck scales up to infinity. We can't say anything about a photon until we measure it and we measure it by its energy content from which we can infer its wavelength and frequency. ie. when it hits a detector and deposits its energy we can work out its frequency and wavelength from how much energy it registers (or with the eye by what colour you "see"). You may now wonder how a photon can deposit its energy all in one go when it has a "length" which would seem to imply that the energy would take time - proportional to its wavelength - to deposit all its energy, and the longer the wavelength the longer it takes to deposit its energy. Well, a "photon" exists at every point from where it was emitted to where it lands, but "once it lands" the wave-function collapses to that point in no time at all. Thus you could argue that a photon is as big as the distance between where it was emitted to where it is absorbed. Its wavelength could then be described as the distance between these two points divided by a whole number. No. That wasn't my point. No, it's not. It's actually where you are failing because you are still failing to understand that you will never see anyone reach the EH if you are outside the EH. It will take an infinite amount of time for them to reach the EH from any observer outside the EH. ie. never. No, that's an assumption that you have no evidence for and the point under discussion. Consider this: I measure the mass of a BH and find it is 5 solar masses. I take Hawking's equations and work out that the BH will exist for 8.268976e+85 seconds. I then dive towards the BH. As I fall toward the BH I look back to where I came from and see that as I get closer to the BH the Universe is speeding up relative to me. At some point before I reach the EH - where time dilation is infinite - the dilation will be so great that 8.268976e+85 seconds will pass in a tiny fraction of a second as measured by me and the BH will have had enough time to evaporate. So when did I cross the EH? I'm sure you agree that 8.268976e+85 seconds is a lot less than infinite, no? I'm well aware that clocks in the same reference frame tick at the same rate. I think rather it is you that is not understanding what I am saying.