Modern and Theoretical Physics

As we all know there is a correspondence between the tensor rank of a field representation, and the spin of the associated particle - so for example, a spin-½ is represented by a spinor field, a spin-0 by a scalar field, a spin-1 by a vector field, and so on. This seems to just be taken for granted in all of the texts I have seen, but is never really explained. So my question is, what is the deeper reason for this correspondence ? Is there a mathematical reason for it, specifically in terms of group theory and/or differential geometry ? Any ideas, anyone ?

So I have recently ( 2-3 weeks ago ) begun teaching myself QFT in earnest. Truth be told, it is hard going - while the basic concepts are straightforward and easy enough to understand, the finer details are most definitely not. The trouble I am having is that a lot of texts seem to focus much on the mathematical details ( for obvious reasons ), at the expense of the bigger picture. I am currently struggling through the Weinberg-Salam part of the SM, and I pretty much had to piece together the bigger picture from all the maths involved in it. I wonder if someone here can confirm whether or not my understanding is correct : So the basic idea is that we have a Lagrangian…

Is there any property or function of a photon that would make them inconsistent with being dipoles? Acting as force carriers, propagating at the speed of light, having 0 mass,...?

I was just reading this article: LHC sees hint of boson heavier than Higgs and while browsing stumbled on this article shortly afterwards: Recent study predicts that Higgs particles are much heavier than earlier observation . What's the likelihood that the possible particle is just a second Higgs? How does this effect the standard model. If it's not another Higgs, and is confirmed to exist, what are possible theoretical candidates which could account for the particle. If it's something completely new, what could it be and how could it effect our current models?

Let me preface this by saying I'm not a physicist, or physics student. Now that we have that out of the way, I've been playing a game called Elite Dangerous and seeing a neutron star there reminded me that while I've looked up plenty on black holes, I'd never really looked into neutron stars very much. So I was looking up the composition of a neutron star, etc. and I read (on this website http://science.nationalgeographic.com/science/space/solar-system/neutron-stars/) thata neutron star's birth involves " A neutron star's almost incomprehensible density causes protons and electrons to combine into neutrons." Now, is this correct? How do protons and electrons combine i…

Hi, I love science, but I am not a professional, just a free thinker. I have this crazy theory in my head for years, and I don't know where to find somebody to disprove it (or acknowledge its plausibility) If you a reason to think it's absurd right away : please explain it to me ! Here it is : 1) Matter and antimatter would have a positive mass. 2) We are all wrong about the nature of Quantum physics : instead of being a strange generator of particules and antiparticules, void would be filled with a great quantity of matter and antimatter equally, constantly interacting. All sum of charges of those particules would be exactly equal to zero. They wouldn't…

Has anybody ever placed several double slit "cards" in parallel? I wonder what might happen if we lined up about six cards one behind the other, and made every card in the sequence a little larger as they fade back towards some termination plate. 1) Would the wave catch the edges of the larger cards and record several electron positions? If so this might prove that what we are actually seeing, in the original experiment, is not the electron that was fired but a clone produced from the wave. 2) What might happen if we put the polarizing film on the fourth or fifth card back? Is there any group doing different variations of this experiment? I'd like to…

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Hi, I was thinking about time being the 4th spatial dimension, thanks to a book I'm reading these days. Nothing special, till I tried to imagine this in the smallest possible scale. So, I drawn the classic space/time graph and marked two points on each axes: y and y+Planck lengh on the space axis x and x+Planck time on the time axis Now, looking at how the smallest 4 dimensional particle could be rapresentend in this graph, I figured out that it should have these attributes: lenght, width and height equal to the Planck lenght lenght in the 4th dimension ( or "duration" ) equal to the Planck time But, being time just another spatial dimension, i thought t…

Time Travel would very well break the laws of the Universe yes there are some thing for why it is possible but here is my reasoning for why it is Impossible Okay, lets say you have built a time machine in 1999 that time machine cannot come back in time past the year 1999 because the time machine did not exist yet, and is destroyed in the year 2012 so it cannot further than 2012 but still the time machine cannot even go into the future because the future has not happened yet. Then also when you travel in time saying it is even possible you' go back to 2003 and let's say you were in Rhode Island in 2003 but the time machine was in Ohio you would suddenly be in Rhode I…

This may be kind of an odd question, but provided that two hydrogen atoms are in a position where they are about to fuse, how long does this process actually take? As an extra question, how long would it take to fuse every atom in 1 gram of hydrogen, assuming you had conditions that allowed for this to happen?

What does the waveform of an electron in orbit look like ? And what if it is dislodged (made free) ? Please advise.

If you have two large gravitational masses some distance apart. Then another smaller mass passes through the middle of that distance is there any canceling out of force acting on the smaller mass? You can possibly toss out the word force, and substitute a relative term though I am not sure what that would be. Maybe something like intersecting space time curves, and the effect on the smaller mass.

Hello! I was reading up about strontium uses, and apparently one of its main characteristics is that it absorbs x-rays very well. Hence I started wondering: what is the mechanism of absorption (even if it is complex) generally? And why is Sr so good at it? Thank you, Daniel.

Here formulation of physical model of inductance: url deleted

dont judge just for fun ok so as light strikes on matter it exerts force on it which by even almost 0 amount of weight is increased so when a shadow is casted over it then that increase in weight is lost so you can say that the mass of a shadow is negative

Good afternoon, as you will read in the introduction of the attached document (via Dropbox), I have created a publication which is comprised of two equations which are derived and extrapolated from a book that I created in 2015/2016. The name of the book is: Probability, Quantum Mechanics, and Probability-Quanta. The latter consists of various thought experiments and postulates. In addition to the electronic copy in this e-mail, I will be sending your department a physical copy of the book (initial publication run of 200). I have included scans from the original book in an effort to demonstrate my work and in the hopes of having the experiments conducted. For your review…

As a friend on this forum suggests, I just want to " have the ability to read modern papers and perhaps make some contribution to the field with no monetary compensation". I graduated with bachelor of computer science, and with a master of finance after. However, I find my curiosity for the universe and life is not saturated with the job I am doing ( IT and finance stuff, which is simple compared to theoretical physics ). I want to understand the modern theoretical physics to understand this world. Says, for example, I am 26 now, will I be able to read and understand modern theoretical physics papers, through self-studying theoretical physics in my spa…

I read this paper and really don't understand a lot of it. But I did the impression that the gist of it was that photons polarize space in some preferred direction as they move through it. Am I on the right track or not? http://arxiv.org/pdf/quant-ph/0408017v1.pdf

Metamaterials (from the Greek word "meta-", μετά- meaning "to go beyond") are smart materials engineered to have properties that have not yet been found in nature. They are made from assemblies of multiple elements fashioned from composite materials such as metals or plastics. The materials are usually arranged in repeating patterns, at scales that are smaller than the wavelengths of the phenomena they influence. Metamaterials derive their properties not from the properties of the base materials, but from their newly designed structures. Their precise shape, geometry, size, orientation and arrangement gives them their smart properties capable to manipulate electromagnetic…

Regarding the Tokamak reactors they are using in Germany to create fusion, I had a couple questions. If fusion, in stars, is catalyzed by huge gravitational pressures within objects massive enough to create fusion, are they using magnetic fields to essentially contain that amount of pressure in the Tokamaks? Is this how the plasma is enabled to reach the temperatures it needs to become a plasma? They have to contain it, yes? And not only contain it, but contain it with the same amount of force that you would encounter within the gravitational pressures of stars? And they do this with magnetic fields in specific geometrical shapes? Does that at all describe what is ha…

The problem statement, all variables and given/known data (1) An ideal digital detector only suffers from quantum noise. If, after being exposed to 5 µGy the mean pixel value in the image is 100 and the standard deviation of the pixel values in the image is 5, calculate the SNR? The relationship between pixel value and detector dose is linear. (2) What is the effect on SNR of applying a linear gain of factor 4 to increase all pixel values Attempt at a solution As I understand SNR = 100/5 = 20 (but I am not certain; it could be 100/sqrt(10)) - clarification would be helpful Also I think gain has no effect on SNR (as it increases signal and noise by the same amount) b…

Hello, Considering that lasers can create significant radiation pressure, what are some applications you propose for utilizing the radiation pressure of electromagnetic waves? Also, what are your opinions on the Abraham-Minkowski controversy?

Can you have a hot ionized plasma trigger for a thermonuclear reaction, as opposed to the conventional fission reaction ?

Hi, Here you have a video about 3 minutes long that tries to explain the atomic nucleus. It consists of a sequence of pages,27 in total, each lasting ~5 seconds (so you have to pause each time) that describe the proton-neutron interaction, the proton-neutron distribution inside the nucleus, the He-4 nucleus, the core of a nucleus, the average binding energy trend, the relation between the ionization energy and the atomic nucleus, the alpha decay and the nuclear fission. url deleted