Quantum Theory

In quantum eraser experiments, getting information about one entangled photon decides if the second photon behaves classically or quantum (interfere). Optical lengths for these photons chooses time order of these events, so we can delay the "decision" to happen after what it decides about. But in "standard version" of such delayed choice quantum erasure this decision is made randomly by physics. I've just found much stronger version - in which we can control this decision affecting earlier events. Here is a decade old Phys. Rev. A paper about its successful realization and here is simple explanation: We produce two entangled photons - first spin up, second spin dow…

Gauge bosons which I think are the particles that carry force are suppose to be time-dependent in relativity, (since in relativity that's what those forces are, even if they "propagate" at the speed of light), but in the standard model they travel physical distance over time, but there seems to be two conflicts with this: As you approach the speed of light, there should be fewer particles that are able to exchange going in the direction that an object near the speed of light is going, which means near the speed of light, atoms should more or less fall apart. And then, with black holes, the event horizon is currently modeled to be a boundary where time stops flowing f…

If I have two particles and I separate them by many light years, one on Earth and one near a black hole, since their states would be instantly determined by any measurement via their inherent mathematics, wouldn't I instantaneously break the entanglement even in far different time dilations to any frame of reference (granted that I am not considered the actual light that would need to travel to a measuring device)?

So you can't escape a black hole using energy, so why not just teleport out? If a particle's probability extend's infinitely, then theoretically a particle could cross the event horizon while it's probability still occupies spacial coordinates outside of the event horizon and teleport outside the event horizon before getting sucked in again.

According to my understanding, the more...atoms you have, the strong something like a magnet is, or at least the stronger the range it has. If I have two magnets made of the same material, one will have a greater range than the other. Is this because there are in fact force individual carrier particles which act upon wave mechanics and therefore combine to make more powerful ranges? Because if you look at simple sine mechanics, when you add two of the same sine wave together, the result is basically the same thing except which twice the amplitude...

Is there a physical meaning for where the turning points intersect with the sign change of the second derivative of a wave function? I ask because there's this picture and I think I saw something talking about it somewhere, but I don't completely understand what the point is.

Is my understanding correct than somehow single charged particles such as an electron have two varying magnetic poles? How does this happen? I think I was trying to figure out why magnetic monopoles are impossible, and I found out something about particles themselves having poles, so that even if you have something of pure electrons, it still somehow has two poles.

It seems like the more I look at complex physical systems, the more they have the same patterns I find in fractals. I can't remember what it's called, but when using sine waves in parametric equations there is sort of a "time" that the function takes in order to return to a previous state and overlap itself, or maybe it's simply called completing a cycle, and this same type of phenomena of repeating occurs in both fractals and wave mechanics, so I was wondering if there was some complex way fractals could be used to describe quantum mechanics and how it evolves to things on the macroscopic level.

In metallic bonds, there just seems to be some kind of general random field electrons occupy and hold a metal together, but are there specific energy states in metallic bonds or is it just a mesh? And are electrons entangled in metallic bonds?

I did a search, but could not find anything on this specific problem, so apologies if this has already been answered. I just received my marked QM assignment (got a distinction, thought I'd slip that in ). In one of the essay style questions, I deliberately added a bugbear to prompt tutor feedback. However, it was not particularly satisfactory, and no different to what I have already read. Supposing I made a measurement of position on a system, that caused collapse of the wave function to a given eigenstate. If I make a measurement immediately after the collapse, (i.e there is no time evolution due to the Schrodinger equation) I should obtain the same value, sa…

I've been reading about the subject and stumbled upon the quantum many-worlds theory. Is there any observable or mathematical backing for a 'new universe' sprouting from every possibility?

While reading about electric current,i got the information that electrons flow from negative terminal of a battery to positive terminal.it has been mentioned in the book that electrons jump from atom to atom with a very slow speed called drift.we know that metals have a tendency of losing electrons.Then why and how would atoms of metallic wire gain electrons from the negative terminal of battery?And one more question arises that if they drift slowly then why is electricity so fast?

I'm currently reading Stephen Hawking's book "A Briefer History of Time" and I was a little confused by the suggestion that the uncertainty principle undermines determinism, as stated in this sentence from the book: As explained in the book, the uncertainty principle states that the more accurately the position of a particle is measured, the less accurate the measurement will be of the particle's velocity. Therefore, the "initial conditions" of the system can never be accurately known in order to determine the past or future state of the universe. This much is easy to understand, but it seems that the uncertainty principle really only undermines our ability t…

By comparison to position, and momentum (proportional to the derivative of position); and the parallel to time, and energy (as the time derivative); is there a "time operator" [math]\hat{t} \equiv t \times[/math], having eigenstates [math]|t_0\rangle = \delta(t-t_0)[/math] ? If particles must be normalized w.r.t. space, s.t. [math]\int d^3x \Psi(x) = 1[/math]; then why aren't wave-functions normalized, w.r.t. time, s.t. [math]\int dt \Psi = 1[/math] ? Vaguely, to tie in to relativity, would seemingly require combining time & position, into "quantum events" (t,x).

I understand, that "while decoherence typically happens very swiftly, it is not quite instantaneous" (dickau); and, that "decoherence" and wave-function "collapse" occur, in chemical reactions: If so, then the "contractive collapse", of the quantum 'particle' "field" -- cp. "Erwin Schrodinger thought that the quantum state of a particle -- in the form of its wave-function -- was a real field, as a classical electro-magnetic field is real" (mermin) -- occurs "quickly" but not "instantly" ??

Hi, I had been looking all over the internet for this equation that describes everything except gravity. I finally found it but it is on a shirt! :S Anyway, please could I know: The name of the equation What it means And it put in layman terms Any other information you have on it would be great. I'm new to it and it interests me so i would really like to know more about it. Thank you. Edit: Forgot the bloody link! Stupid me. XD http://www.zazzle.co...614641326468730 Edit 2: I think it is called the Higgs Field. But I'm not sure.

Sometimes things are really obvious and you just don't notice them. Here's what I was thinking. If you have electron gun A firing electrons at slits A and B and you will get a difraction pattern. However, If you have one E-gun A firing at slit A and another E-gun B firing at slit B and there is a wall between slit A and B (on the E-gun side) you will not get a difraction pattern. My assumption had always been that electron A inteferes with electron B but this is not the case, electron A inteferes with electron A. (<that's the obvious bit) This is true when on electron is fired at a time and when 'n' electrons are fired they all interfere with themselv…

we all, even Einstein say that space time is a fabric in which its curvature due to the mass is the gravity. Ya, I know that, but in reality, is this 'fabric system' possible? Because the real space is 3 dimensional and how could be space along with the time be a fabric of 2 dimesions?

Ok, I'm going to take a leap and see if this works... Degenerate matter, very dense, much like boss-einstein condensates, but are the atoms in degenerate matter entangled?

If you graph the actual oscillation of a sub-atomic particle, it oscillates between positive crests of probability and negative ones, but where is it oscillating into when at the present time it is oscillating at negative probability? Is it oscillating in some other dimension? Or do you use the absolute value?

I am just asking what are the main property/style of the Strong Force? Can anyone advise?

I'm not talking about fractals, I'm talking about using only 2.3 coordinates to describe something.

Suppose you fire a photon from some ideal source to a target point on a flat surface 1 m away. Suppose that the smallest distance from the target that you can theoretically hit, with probability P, is epsilon. Is P < 1 for any finite epsilon? Is there a remote chance of missing a target no matter how big it is? Is epsilon related to the Planck length? Is it related to the photon's wavelength? If the target were moved to say 10^100 m away, would epsilon be scaled by a factor of 10^100?

I've looked over this one a few times and I'm still not quite sure what to make of it. Reading over the various blurbs on the topic I can say that I am familiar with most of the components in their individual form but I don't understand what Bra Ket is trying to do to put it all together. I was just wondering if someone could give me an immediately obvious example of application and somehow relate it to the more pertinent matters of QM? Looking over the Wiki again, am I simply missing the point that it is an inner product? I mean an inner product is nothing for me to run away from, but Bra Ket has been something I've always felt kind of queezy looking at. And I ke…

I must say I am the least aware of who Brian Cox is and I believe the only reason I know the name is because of #SFN--I lead a sheltered life apparently, and am illiterate (I simply don't read magazines or newsprints.) At any rate this was one time I had passed on the reading of a post from Swanson as I tend to avoid anything that relates to this sort of material, especially when it involves concepts that are much beyond me. I took a second look, and the comments made me watch the video; I mean hey 'Prof. Cox' took the moment to address, the least I can do is watch the video. Useless facts aside and having had no intention with the above . . . . I think the idea i…