Quantum Theory

For the Elitzur–Vaidman experiment, I need to check that I have the right idea about the interferometer, and the process of splitting photons, but one step at a time. My understanding of the interferometer is that it has two paths (1 & 2) from the emitter (E) to the detectors (d1 & d2), that identify the path(s) taken by the photon, and that there must be another detector (D) that registers the resulting interference pattern after recombination. It would be wise to check this first, as, if my impression is wrong, it might influence my need for further questions. Happy New Year to everyone.

I saw this recent PBS Infinite Series YouTube video entitled "A Breakthrough in Higher Dimensional Spheres." It's host describes and discusses various techniques for visualizing spheres in multidimensional spaces which, being a novice, I found very informative. Among several examples, the video's host described how a 3D sphere might appear as it passes through 2D space and how a 4D sphere might appear as it passes through 3D space. Her description recalled to me observations reported as a common quantum occurrence where virtual particles pop in and out of existence. I now understand that those observations involve more than just something materializing from nothing bu…

Just trying to clarify my understanding of some concepts regarding inner products and spaces. So the inner product in Dirac notation has been defined in my book as: [math]\langle a|b\rangle = \sum_i a_i^*b_i[/math] Does this definition include the complex conjugate, [math]a_i^*[/math], just so that the property [math] \langle a|a\rangle = \sum_i |a_i|^2[/math] is satisfied? i.e. is that property a defining feature or the corollary of some other defining feature? Also, is an inner product space then just the space spanned by the two vectors that form the inner product? For instance the inner product of cubic polynomials has been defined in my …

I find it difficult to follow the analysis on experiments that investigate quantum entanglement, there seems to be something fundamental about quantum entanglement that I am missing. Perhaps if I step through a simple example, it will show up what it is that I am misunderstanding. Say a source of entangled photon pairs are used in an experiment, such that the photons pass through two vertically orientated polarizing filters, positioned either side of the photon source, with one filter slightly further away from the source than the other. For the sake of simplicity, it is assumed that the polarizing filters are perfect - that any photons that make it through are po…

I have just come across the overlap rule used to calculate the probability of finding any particular energy eigenvalue, but little about it was explained. Is an overlap integral the same as a convolution of two functions?

https://www2.physics.ox.ac.uk/research/ultrafast-quantum-optics-and-optical-metrology/attoscience-and-strong-field-physics/attos-0

At first I would like to ask if i understand this topic. ref: http://www.scienceforums.net/topic/87347-why-hidden-variables-dont-work/ https://youtu.be/ZuvK-od647c So Bell's Theorem essentially claims to disprove the existence of hidden local variables in entangled photons/electrons; and it concludes that action-at-a-distance is present (or superdeterminism, global variables). Per experiment, by "repeating the procedure over and over" (4:38) and considering the expected unequal distribution of frequencies (6:31) as if there were hidden variables (Bell's inequalities) or "hidden plans" (5:00), and comparing them to the actual recorded distribution of results …

I don’t know the math behind time, but I feel that time is something that is always changing. So to try to come up with the math that makes it work with all the others I feel is the lack of understanding. I want to look at it as if it was sound. Sound when it goes out and comes back gets weaker every time until a new sound is added. So can time change the same way as sound. If this is the case the more you are always from an object in time the less it effects time. The same as sound gets weaker as it moves as does gravity. So if you wanted to bend time would not you only have to mass the effects that objects have on other objects. To me time is like a river if you place…

Quantum theory is the theoretical basis of modern physics that explains the nature and behavior of matter and energy on the atomic and subatomic level. Lets discuss virtual photons and how they are exchanged by electrons. Virtual particles are an accepted particle in physics. Exactly what are virtual particles?

Everywhere I turn "superposition" has its hand in making things weird.

Frank Wilczek, a Nobel Prize-winning physicist at the Massachusetts Institute of Technology : " Richard Feynman looked tired when he wandered into my office. It was the end of a long, exhausting day in Santa Barbara, sometime around 1982. I described to Feynman what I thought were exciting if speculative new ideas such as fractional spin and anyons. Feynman was unimpressed, saying: “Wilczek, you should work on something real.” Looking to break the awkward silence that followed, I asked Feynman the most disturbing question in physics, then as now: “Why doesn’t empty space weigh anything?” " https://www.quantamagazine.org/20160705-feynman-diagrams-nat…

Can it also be said that the measured photon is disassociated with wave phenomena? Or could the wave be morphing, on demand, in a way that doesn't cause double slit photon interference?

I understood some of the words http://www.nature.com/articles/ncomms11027

Before you laugh this off, how could you possibly know for sure gravity doesn't effect interference at the atomic scale? Shouldn't this have been the first test they did on ISS?

Too ridiculous? Well, so is quantum weirdness to begin with.

http://phys.org/news/2016-09-schroedinger-cat-molecules-exquisitely-movies.html

So i just learnt that momentum is equal to plank's constant over wavelength,[math] p= \frac{h}{\lambda} [/math], and that this applies to photons. So if photons have momentum why is it said they do not have mass? Has this got something to do with relativistic mass and if so is there any way of understanding it without general relativity (i might be able to cope with special relativity). Cheers.

What precisely is an observer, in the way they are referred to in Quantum Physics? After agreeing on a definition, can we try to answer this question by listing things that: Almost definitely observers, Maybe observers, Almost definitely not observers. We can start with the definition from wiki, a quote from Werner Heisenberg, Physics and Philosophy, p. 137 "Of course the introduction of the observer must not be misunderstood to imply that some kind of subjective features are to be brought into the description of nature. The observer has, rather, only the function of registering decisions, i.e., processes in space and time, and it does not matter wheth…

I have heard alot about the different dimensions, I understand 1D, 2D, 3D, but 4D and 5D are a little confusing to me. Time is supposedly a dimension because you CAN travel through it given the right conditions(I.e gravity anomaly) But the 5th dimension is completely out of my understanding. I have read that there are 10 dimensions (http://www.universetoday.com/48619/a-universe-of-10-dimensions/) but I think that may be just a little bit leaning towards a theory rather then fact. If someone can explain what the dimensions are and how they work that would be nice. Thanks! P.S. I know I am going to take some heat about the gravity anomaly but if I do take heat for it …

I've been reading up on some QM lately and one of the things that gets my mind tied in knots is the how the measurement of an electron affects it's path in the double-slit experiment. Isn't our own observation with our own eyes, which uses light in the environment, a form of measurement? If some detector placed within the experiment affects the path of the electron, then how does our own measurements with our own senses, which can be thought of being detectors, affect the path of the electron? We use reflected light as a source of information about the world. Does this light in the environment interact with the electrons in any way? If our own observation with our eye…

This is a question from my friend. We were having a debate about it in school. My friend was giving a speech about it. He said that a vacuum can be stretched. I countered it by telling him that there is basically no matter to be stretched, so how can it strectch. I also added that a vauum can spread. For example, if a vacuum was put in a syringe, you can pull the plunger part of it and the vacuum will spread. Can anyone shine some light on this?

So we know light is supposedly simultaneously photons and waves. Have any experiments been attempted to line up the chunks of photons to the peaks in it's wave function?

Atoms do not touch eachother and electrons repel each other therefore what we feel when we touch something is the feeling of repulsion between electrons.. Do you agree with it?

My skepticism is probably just because of ignorance, but.... Regarding the double slit experiment when observing particles before the slit: Since the observation of a particle before going into a slit is an interaction between the detector and the particle, could the change be just a result of the interaction, not really the observation, itself? In other words, could the reduction of the wave be just a physical result of the detector's interaction? What process do they use to detect the particle in mid-flight, anyways?

Theoretically, if we could know more about a particles wave ..could we create a particle by only replicating it's wave?