Laws Definition and 1000 Threads

$$\partial^\beta F_{\beta\alpha} +\partial^\beta A_\mu A^\mu \delta^\alpha_\sigma \delta^\rho_\beta+\mu^2 A_\alpha = 2A_\mu (\partial_\rho A^\rho) +\frac {4\pi}{c}J_\alpha$$

The euler lagrange equation I am using is: $$\frac {\partial^\beta \partial L}{\partial(\partial^\beta A^\alpha) }= \frac {\partial L} {\partial A^\alpha}$$ Now the proca lagrangian i am using is $$L= -\frac {1}{16\pi} F_{\alpha\beta} F^{\alpha\beta} + \frac {\mu^2} {8\pi} A_\alpha A^\alpha -...

How does general relativity shows the conservation of energy. Because I was reading and listening to something today that touched on this subject. It almost seems as though if you scale GR to larger sizes it stops working and turns into an incomplete law of nature like Newton's laws of gravitation.

1. Keplers third law (and the asumption that M1+M2 ~ M1) gives that M_Mars = 4*Pi^2*a^3/(G*T^2) With numerical values inserted Mmars = 4*3.14^2*(9400*1000+3396.97*1000)^3/((6.67*10^-11*(7*60*60+39*60)^2) 2. Phobos needs 7h39 minutes to complete a circle, this gives a speed of...

dP = F dt dE = F dr or if we introduce ds = (dt, dr) (dP, dE) = F ds And both dP and dE are constant in closed system. Some questions: - How does its implies on definition of Force? - Is there some clever geometrical interpretation of Force? - Why P and E seems almost interchengable?

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Hello All We have Newton's Laws of Motion, which have been superseded by Einstein's Theory of General Relativity. Who determines what's a Theory and what's a Law? best regards ... Stef

The Canadian physicist, Lee Smolin proposed in the 90's that laws of nature may evolve and change over time. He begun proposing that only the constants of nature would evolve, while the most fundamental laws would remain the same, but recently he has change a little bit his ideas and has...

Hawking and Hartle proposed a well-known model which postulated a sum over all possible histories considering all compact euclidean metrics to explain the origin of the universe (this is called the No Boundary model). I was wondering whether there is any model or theory (related to cosmology)...

When you pump a bicycle tire before riding up a mountain, the tires may explode. I think it is because of Boyle's law, where since the external pressure decreases, the volume of the tire is supposed to increase and it explodes. The solution says that as the air in the tire expands on heating...

Some physicists (like John A Wheeler, Holger B Nielsen or Ilya Prigogine) have proposed that all the laws of physics (including the most fundamental ones) emerged from a primordial chaos (for example, in the case of Wheeler, he proposed that laws of physics emerged from an initial random and...

Hi, there is no other topics in my adventure in Feynman Lectures that makes me so loss in thoughts (https://www.feynmanlectures.caltech.edu/I_44.html). I seem to understand every sentence. But the whole thing is completely unintelligible. Let me start by asking one fundamental question. I am...

Please I require solutions to this question about Newton's laws thank you

Are there any models, theories or physicists who propose that the fundamental laws of nature come from the initial conditions? Are there any physicists who propose that the most fundamental laws of physics emerged from initial conditions at the origin of the universe? And according to this view...

Hi everyone, I have a question about Maxwell's laws. According to Maxwell the magnetic flux of a magnetic field through a close surface is 0. But his third law says the circuitation of an electric field depends from magnetic flux variation. I can't understand how this can be possible since...

Using the Newton's laws my result was h/hypotenuse and using the energy equations my result was h/D. My results are right ? And if so, how i justify the hypotenuse = D . Sorry for the bad english, the homework was poorly translated.

I have defined 5 currents but I can't seem to solve it. I1+1=I2 (left) I5+1=I4 (right) I2+I4=I3 upper node By KVL I have determined that I2 and I4 are equal, but I cannot determine the specific current across each resistor. Thank you for your valuable help.

For this one circuit, I've applied Kirchhoff's laws as following: $$\left\{\begin{matrix} V-6\Omega I_{6}-24V-2\Omega I_{2}=0\\ 24V-6\Omega I_{6}-12V-24V=0\\ I_{2}+I_{6}=6A \end{matrix}\right.$$ but the values I get for ##I## and ##V## aren't correct... what's wrong?

So, I started by writing down conditions imposed by Kirchhoff's laws, coming up with a system of 3 equations with the 3 unknown currents: $$ \left\{\begin{matrix} 9V-8\Omega I_{8}+6V-4\Omega I_{4}=0 \\ 6V-4\Omega I_{4}+3V-2\Omega I_{2}=0\\ I_{2}+I_{8}=I_{4} \end{matrix}\right.$$ But...

I wasn't taught how to do it at A-Level in-detail, because there are no questions that expect you to use them in a circuit problem. They only need you to know what the first and second laws are in words (i.e. conservation of charge and energy). I tried looking it up on YT, but it's confusing...

In some models of the beginning of the universe, like for example in chaotic inflation, space would stop expanding in some points, creating Hubble volumes that could experience different spontaneous symmetry breaking, which would result in different properties, such as different physical...

The main problem is the verse of the 2 currents ## i1 ## and ## i2 ## . I think they both go clockwise, so in the node A we should have ##i1+i2=20A##. Now let's apply the second law (going clockwise). So ##ΔV1-R1*i3 - R2*i4 + ΔV2=0##, where ##i3## and ##i4## are the currents which pass through...

Physicist Geoffrey Chew proposed the concept of bootstrap (related to S-matrix theory) where he denied that fundamental laws of nature existed at all, as it is indicated in a writing in his memory written by one of his collaborators ([https://www.fritjofcapra.net/in-memoriam-geoffrey-chew/])...

Interested in thoughts... Did the laws of the universe exist before inflation phase of the 'big bang' allowing the 'big bang' to evolve, or did the laws evolve later...

I'd like to get a better insight into which aspects of Newton's laws are definitional and which are falsifiable. And moreover, of the definitional aspects, why these are good definitions. Netwon's laws can be phrased as follows (from Wikipedia): First law: In an inertial frame of reference, an...

If it were supposed that time were a 4th non-spatial dimension how would it influence the gravitational movement ? The problem I have when trying to solve this invented problem is that Newtonian physics works in coordinates and that there are a lot of ways to find 4d 3+1 hyperbolic-spherical...

I need help to understand this problem taken from Mechanical Vibrations by S. Rao I know that the equations of motion could be obtained in various ways, for example using the Lagrangian, but, at the moment, I am interested in understanding the method he used. In particular, if I'm not...

I'd like to get some feedback on the following argument. Gallilean mechanics, with the Gallilean transformation laws, is a perfectly consistent theory. Special relativity, with the Lorentz transformation laws, is another perfectly consistent theory. The question is - can we have some physical...

This questions was brought to my attention by Kazu Okayasu. According to probability theory the probabilities of mutually exclusive events add upp. As an example we can distribute 2 balls in two boxes with two compartments each. So there's a box on the left with a lower and an upper compartment...

So formulating them was easy, just set ##C:=D\cup E## in (1) and set ##C:=D\cap E## in (2) to see the pattern, if ##\mathfrak{B}## is a non-empty collection of sets, the generalized laws are $$A-\bigcup_{B\in\mathfrak{B}} B = \bigcap_{B\in\mathfrak{B}}(A-B)\quad (3)$$...

A quantity ##p## can be expressed as the product of a dimensionless number, ##\lambda_p##, and a unit, ##u_X##:$$p = \lambda_p u_X$$When we write the equation of a physical law, do the symbols represent the physical quantities ##p## or their dimensionless coefficients ##\lambda_p##? That is to...

If you break the laws of physics, do you go to jail?

Here is my question that I have been trying to do Had tried to attempt it and got there as my answers? Not particularly sure if I had done part b) right from the simultaneous equation I had to solve to get the current values Appreciate for any help! Thanks

Momentum ##\vec{p}## before collision is momentum of proton of the energy ##E=76.4\mbox{GeV}##. Law of conservation of energy is E+mc^2=E_1+E_2+...+E_n mc^2=0.94\mbox{GeV} We could generate only even number of particles after collision because of law of conservation of electric charge. Also...

Block A is accelerating at a= 49.6/0.5 m/s (99.2m/s) Block B force is F= 3kg * 99.2 = 297.6N but I'm not sure where to go from here?

Hello, I have problem with this task, I must solve the triangel if i know a:b=2:3, c=15 cm, alfa:beta=1:2.Can you help me please?If you know it write me way how you solve it Thank so much.

Hey everyone! Had an attempt at this circuit question, but wanted to check if I got the set up right in order to find the current in the 3rd wire? Here is what I have done Thanks!

the attached files are a diagram of the circuit. also I believe I figured out how to proof equation (7) but I'm lost on how to proof (8)

Equivalent capacitance before and after remains the same. Now the 10F capacitor (which was initially connected in parallel with 20F) would have 30 C charge. Hence an additional 20C must have been supplied to it. The only path which may supply the charge is through battery. However this leads...

Hi. As far as I know, during the unitary evolution of quantum states, conservation laws are respected. Obviously this can't be true for the measurement process, if we only look at the system and exclude the observer. Now the simple explanation I've heard about this is that in quantum mechanics...

Is there any version of string theory or cosmological inflation that allows the most fundamental laws and constants change between universes? String Theory and Cosmological Inflation are two theories or models that allow multiple universes to exist. Laws and constants of physics could change...

I was just thinking about this earlier and couldn't come up with a good enough resolution. I'm guessing it's a matter of convention more than anything. If we have ##x^{2} = a##, taking the principle root of both sides gives ##\sqrt{x^{2}} = \sqrt{a} \implies |x| = \sqrt{a}##. Yet evidently if...

Hi, I found this question/s online and I was wondering if somebody was able to explain the answer given, specifically the first bit that says R1/(R1+R2) = R4/(R3+R4) (is this something to do with an equivalent resistor to replace the two in series on each side? But why are R1 and R4 the...

A cabin is accelerating with acceleration a .To apply Newtons laws inside it ,we need to include an accleration -a. Now if this cabin is rotating about a point in a plane,can we apply Newtons laws in it? How?

Hello to all. Second post here so I apologise if I post to the wrong place with wrong altitude etc We have a schematic of a problem like here: https://www.physicsforums.com/threads/conducting-rod-is-free-to-move-over-a-loop-under-influence-of-b-field.750763/ The conducting rod ab shown in the...

Hello everyone, I have to write a paper about entropy and how it relates to the laws of thermodynamics, energy, and work. I have taken a deductive approach starting from the zero-th law to the second law of thermodynamics as follows. Entropy is the disorder of a system (Class Video, 2019)...

Hi All I will state the issue succinctly. This is a I level thread so I will suppose people know Newtons Laws. Newtons first law follows from the second which is a definition of force. So it has no actual testable physical content. The third law is equivalent to conservation of momentum...

What is the author meaning by that, I literally just read in section 5.1, that the depending on the energy loss of the electrons that make up the substance, this energy will be released as photons. Since this is particular for each atom, it explained how we can tell which element is wich. So if...

Here is my attempt at setting up the equation: I set up the equation to find the acceleration of the box: F-Ffr= m*a after finding the acceleration, I can use the acceleration and plug it in the formula v^2=(v0)^2+2*a(x-x0), which will get me the value of (x-x0)The solution sheet says that F...