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Quantum Gravity Singularity Question?

I am not a expert in QG (Quantum Gravity) or GR (General Relativity) for that matter so please forgive if I make any small mistakes, its just a curious question but I know that a singularity is a ...
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Deriving the Lorentz factor

Recently, I learned how to derive E = mc^2. However, to do so, one must accept the relativistic mass equation. How does one derive this?
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The g-force of common objects hitting the floor

At my friend's work they have an accelerometer which measures the force with which certain objects hit the ground. He claims that from four feet high, cell phones hit a solid metal surface with a ...
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Is it possible to directly pump a laser using sunlight?

Typically in the old days one would use a flash tube to pump a ruby crystal. Is there any way, or any lasing material, that could use concentrated sunlight directly for either continuous or pulsed ...
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Final charges on Capacitors connected in a curcuit

Capacitor C1 is charged to a Potential Difference of 10V. It's capacitance is 2 microFarad. Capacitor C2 is charged to a Potential Difference of 15V. It's capacitance is 4 microFarad. Now the ...
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Value of Planck scale

I read several times that the Planck scale is the energy scale at which the effects of gravity are comparable to the effects of the other fundamental forces. How can I show that this actually happens ...
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This question is based on a previous question I asked, Q. [1] In this question, I proposed an example of a non-local Lagrangian (functional), I'm revisiting it here: $$\mathbb{L}=\frac{1}{2}\int^t_0 ... 0answers 31 views Water as heat source in a heat pump Consider we have water flowing in a pipe, which is working as a hot source for a heat pump. We are able to know the temperature of the water in both ends of the pipe, yet we don't have information ... 1answer 75 views Rindler and Minkowski space future/past infinity In my black holes course, we are looking at the Penrose diagram for 1+1 D Minkowski space. My notes don't specifically describe i^{\pm} (future/past timelike infinity) but do say all timelike curves ... 0answers 33 views Vertex of gauge boson interaction in an arbitrary gauge Let's have interaction between some gauge boson (for example, W boson) and some other field, for example, let assume \bar{u}\gamma_{\mu}(1 - \gamma_{5})d W^{\mu} + h.c.. Let's then use gauge ... 1answer 69 views Can an Atom be negatively as well as positively charged simultaneously? For example there are three atoms- atom A, atom B, atom C. Atom A has 3 electrons, atom B has 4 electrons and atom C has 2 electrons. If we bring together atom A and atom B, in this case atom A is ... 0answers 60 views What happens if the big bang occurs once again? according to string theory every universe is a large brane and big bang is a event which takes place when two branes collide with each other. if our universe brane collides with another brane there ... 0answers 29 views Accuracy of quantum mechanical algorithms Is it possible for a quantum mechanical algorithm to ensure when the wave function collapses that the right answer will be obtained 100% of the time? For this, I am excluding processes such as ... 0answers 36 views How to specify boundary conditions as function of curvature in dynamic elastic beam pde? In this article (already mentioned in this question) the dynamics of a planar elastic beam with "cantilever constrains" (one clamped end and one free end) is modeled. Using the Euler-Bernoulli Beam ... 2answers 290 views The equivalence between Heisenberg and Schroedinger pictures In quantum mechanics, the two pictures of Schroedinger and Heisenberg are taken as equivalent, where in the former wavefunctions are time variants and operators are not, and in the latter it is the ... 0answers 38 views SR: vector field and change of reference [closed] If U and V are vector fields, then the derivative of U along V is the vector field \nabla _V U with components$$\nabla _V U^a=V^b \frac{\partial U^a}{\partial x^b}.$$I would like to verify ... 1answer 60 views Combination of current sources Most books say that to connect sources in series, the current sources will be equal in magnitude. I really don't understand the meaning of this statement. What happens if you connect current sources ... 3answers 7k views Why doesn't light affect a compass? In our daily life a lot of photons of visible light, infrared and radio etc move around us. We know that light is an electromagnetic radiation. So why doesn't that electromagnetic radiation affect a ... 2answers 126 views Does a photon travel in all directions? For example i am standing and a beam of light is passing in front of me. I am able to see that beam of light so does it mean that photons are travelling in all directions other than the photons which ... 3answers 272 views What is actually a conservation law? Though in his lectures, Feynman didn't define conservation law, he did use it while explaining divergence theorem: [...] heat is conserved. That is, no heat is generated inside the material and ... 2answers 94 views Is the interference quantum mechanical superposition the same as entanglement? [duplicate] Are the interference of two wave functions an equivalent way of saying that they are entangled? 3answers 169 views Why are log scales so common? I am currently reading a very nice book on scales in physics. There is a discussion on the different physical scales which are based on the effect of the corresponding phenomena, the given examples ... 0answers 22 views Orthogonality preservation vs. preparing a state I'm trying to learn the fundamentals of quantum theory, lately mostly using the lectures by Prof. Susskind which Stanford University made available on Youtube. Here is one thing I have trouble ... 1answer 63 views Experimental determination of \Lambda_{QCD} I have a question about \Lambda_{QCD}, the energy scale at which there is a transition from the regime of perturbative QCD to quark confinement. How it is measured experimentally? 0answers 32 views Recursion relations and stability analysis I have a recursion relation in the form of the following two equations: X_{t+1} = X_t + V_{t+1} \\ V_{t+1} = wV_t + cy(g-X_t) I want to write these two equations into a matrix form so that I can ... 0answers 73 views Ernst potential from Kaluza-Klein reduction of axisymmetric space-time Following appendix A of "Ergoregions in Magnetised Black Hole Spacetimes" by G. W. Gibbons, A. H. Mujtaba and C. N. Pope, starting from the Lagrangian$$\mathcal{L} = \hat{R} - ...
In the following diagram: Point(c) is a going into the page and attached to the disc, Point(c) applies a torque($\tau$) to the disc, and it starts to rotate due to that torque. And if point(c) was ...