Explain Definition and 1000 Threads

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Hi all, I understand what the integral does - it calculates the area under a curve and can easily see how it could be used to calculate an area of land. What I do not understand is really the physical meaning when it comes to the real world. Here are some examples: 1. A set of data...

I truly am not sure. I assume it is that because everything has inertia, an a tendency to remain in a constant state of motion, when the clothes are quickly spun around they cannot remain in a constant state of motion (of either rest or constant velocity), but the water is "pushed"/spun out of...

When we observe distant time dilation effects, usually indicated by redshift, there are three possible explanations: 1) The speed of light, is slower there and then; 2) Space, is contracted for light there and then; 3) The frequency, of specific light is slower there and then. However, it is...

Deur Gravitational self-interaction Doesn't Explain Galaxy Rotation Curves this paper A. N. Lasenby, M. P. Hobson, W. E. V. Barker, "Gravitomagnetism and galaxy rotation curves: a cautionary tale" arXiv:2303.06115 (March 10, 2023). Directly comments on Deur's theory of self-interaction...

Can you please explain why is there work done by F2(on photo of textbook explanation of Bernoully equation (photo below)). I can understand that W2 is caused by F2 which is gravitational force(screenshot photo from YT). But for the explanation in textbook pipe is straight, no height...

//program showing an advantage of using arrays public class Arr3 { public static void main(String []args) { System.out.println("There are 31 days in the month of Jan"); System.out.println("There are 27 days in the month of Feb"); System.out.println("There...

What is the main reason for a free field staying free according to Haag's theorem?

Hi! Isn't gravity just a smaller object moving toward the lower energy state created by a larger object (time slows down the closer you are to a massive object)? Why do we need a force carrying particle for gravity?

Can someone help me understand the answer to this differential? I have the following expression where Now what I can understand the differential of what will be the following?

My assumption is that knowing potential can lead to knowing the position, but I don't know how this can be.

Hi all, I'm trying to derive fuel temperature coefficient in a TRIGA reactor using a monte carlo code. When i do that, if i assume a radial temperature profile along the core, i obtain smaller value (-7pcm/K) than the one achieved with uniform temperature (-9pcm/K). More in detail: in my case...

The Pinnocchio Illusion is where you touch your nose whilst blindfolded and apply vibrations to your bicep, and this tricks your mind into thinking your finger is moving and therefore that your nose is growing. I would like to learn more about this very specific phenomena, namely the ability to...

I've wanted to check the accuracy of my Blood Pressure Monitor (BPM) (an automated Omron unit), and finally found this old (2016) thread on another site (linked below). Prior to this, I only found the less helpful 'compare the reading to your Doctor's office' (BP varies with every reading, not...

How does electrical potential and electric fields change from dipole to parallel dipoles? What does this math demonstrate? What does the equations mean?

It has been below freezing for 3 weeks, 12°F at night and in mid 20s during the day. Yard and garden are frozen 2" deep hard as cement everywhere except 3 row in the garden covered with 1/2" of pine needles. Soil under pine needle is not frozen I can push my finger into the soil 3" deep. How...

As I understand, the main theoretical virtue of Guth's inflation hypothesis is that it explains a bunch of otherwise hard-to-account-for phenomena under the standard big bang model without inflation: the Horizon Problem, the Flatness problem, the Monopole problem, and also the problem of how...

First, here is a riddle: Why did the tortoise cross the road? Because an under-pass was available. An adventurer and desert explorer visited and tried to explain the workings of the solar powered towers at Ivanpah, in the Mojave Desert in California. The person is not any kind of scientist nor...

Here is the code that I am talking about-: n=int(input("Enter a number")) for num in range(2,n+1): for i in range(2,num): if(num%i==0): break else: print(num,end="") If I give n=5 output should be 2,3,5. Here is my dry run. Everything is fine except for 2...

Hi Pfs. I think that QM can explain the classical things explained by classical physics. Using mean values and so on. We know that in a constant magnetic field an electron will rotate on a circle (at the macroscopic scale approximation) I have the answer for the Larmor precession but how to...

"B0 is a static magnetic field (produced by a superconducting magnet) that initially causes the protons in the body to align with the field and precess at the larmor frequency along the z axis . From a mathematical perspective this precession around the B0 axis occurs due to the time evolution...

I have a magnet that will lift only 1 lb of steel with an electric lift. If I discharge a big capacitor into a 1000 turn coil with the magnet in the center of the coil it super charges the magnet it will lift 200 lbs for about 4 seconds. The magnet has a half life of about 4 second for about...

So I have a friend who thinks I'm arguing whenever I state my opinion and explain my opinion. For example, he said he was ugly and I was telling him that he's not ugly and that people are beautiful in their own ways, he disagreed, so then I also pointed out some of his features that are really...

The following figure shows observed distance modulus (µ) vs. redshift (z) data (references of data sources are available): How well do cosmological models, such as ΛCDM and models based on non-expanding universe, explain these observed data? For explanation of terms, please see, Type Ia...

I know it says Universe is eternal, how does that work with gravity? If all the stars and galaxies had infinite time to attract each other why are they still apart? I guess this is a naïve question because no one talks about it but I can't figure it out. Thank you for answers!

Magnetic fields as an alternative explanation for the rotation curves of spiral galaxies ABSTRACT THE flat rotation curves of spiral galaxies are usually regarded as the most convincing evidence for dark matter. The assumption that gravity alone is responsible for the motion of gas beyond the...

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Please explain in simple words, the meaning of the Schrodinger wave equation in the quantum mechanics model of atom. $$\frac{\partial^{2} \psi}{\partial x^{2}}+\frac{\partial^{2} \psi}{\partial y^{2}}+\frac{\partial^{2} \psi}{\partial z^{2}}+\frac{8 \pi^{2} m}{h^{2}}(E-U) \psi=0$$

Check this link: How to override the copy/deep-copy operations for a Python object? Can anyone explain, in layman's terms, what is going on in this source code? from copy import copy, deepcopy class MyClass(object): def __init__(self): print('init') self.v = 10...

A new pre-print makes a sensible and convincing, in my view, argument that phenomena attributed to dark matter are not exclusively or predominantly explained by primordial black holes formed at less than the mass of a star shortly after the Big Bang, by means other than stellar collapse. This...

If individual atoms are indistinguishable from one another, then how can you tell if atom A will experience radioactive decay before identical atom B? ISTM there would have to be some underlying structure beyond electrons and quarks and unique to each atom / particle to be able to do this...

I enjoy explaining spacetime curvature to people with a rank-beginner understanding of GR. But someone asked about that favorite concept in pop-sci, spaghettification. I'm having a hard time with it. If you fell into a black hole, there's no reference frame within which you could describe...

i think solution with récurrence for n=1 then 1=2¨¨^0(2x0 +1) true suppose that n=2¨^p(2q+1) is true shows that n+1=2^p( 2q +1)? n+1=2¨^p(2q+1) +1 ⇒ ??

If f'(x) were a simpler function like f'(x) = cos(x) I would say f(x) = sin(x) + C and then evaluate C by knowing that 2 = sin(1) + C and then C would equal 2-sin(1) the f(x) = sin(x) + 2 - sin(1), f(0) = sin(0) + 2 - sin(1) = 0 + 2 -.841 = 1.58 However the more complicated problem has f'(x) -...

I found some parts of Vol II, Chapter 25 basically unreadable, because I can't figure out his notation. AFAICT he's using a (+,-,-,-) metric, but these equations don't really make any sense: The first one is fine, and so is the second so long as we switch out ##a_{\mu} b_{\mu}## for ##a_{\mu}...

Let's assume a plane wave going in the x-direction. Going by Huygens' principle, each point on the wavefront should act like a source. If that's the case, wouldn't plane wavefront become spherical like shown below? I am so confused

I have a feeling that they will reach the water surface in the same time. How do I explain this in physics?

I run into something strange when I step through debug. This is the program to add names one by one, and each name entered, it will sort and put in ascending order into vector DirV[]. I cannot explain why the if statement in line 51 doesn't work. First name I enter is just 'r', I just put a...

At least according to Tim Anderson Ph.D who wrote the paper in Physics Review. https://news.knowledia.com/US/en/articles/a-5th-dimension-may-explain-quantum-theory-the-infinite-universe-medium-6f1d6fd371e068a07f357b9babe9ab2eec06d034 What do you make of this? "The paper simply presents...

I guess the crux of the question is, where are we more likely to encounter new physics? The standard model already explains almost every experimental result, but not EVERY result. But what are some of the most important results that are either incompatible with the standard model or just...

I wanted to filter out reflections from glass. So I bought a camera with a "circular polarizing filter." It filters out polarized light, adjustable for orientation. The result confuses some cameras, so it also has a second stage which induces circular polarization. The results were...

As far as I understand it general relativity does not explain the origin of the inertial mass ##m_i## in Newton's law of motion ##\vec{F}=m_i\ d\vec{v}/dt## but rather it simply applies the concept to curved spacetime. For example if we have a particle with inertial mass ##m_i## and charge...

Can someone explain a flop transition to me in laymen terms? And what consequences does it have on the universe? Thanks

I just watched season one of Tales from the Loop. It has the mood of Interstellar on the Earth where people live quiet lives of desperation. There’s an underground physics lab nicknamed the Loop where the impossible becomes possible. There’s the people whose lives are affected in strange ways...

Hello guys! I was trying to understand (without involving too much QM) how does reflection works, and why metals reflect almost 100% of visible light while glass does not, and also why when we increase the frequency, metals become transparent. I know that when any single photon reaches a body...

In Feynman's lectures, he explained the ##TE_{10}## mode of waveguide by considering a line source in the middle of waveguide as below: since the adjacent sources are all out-of-phase, which means to have interference, the adjacent optical path would be about half of wavelength as below: where...

Hello! I am planning on applying to physics PhD programs in the fall. My first two years of undergrad I averaged Bs in my lower division classes. Last two years I got a majority of As and A-s in my upper division courses. Those first two years I had some extremely personal extenuating...

Hi. In an Elitzur–Vaidman bomb tester, will the guiding wave be different in a situation with a live bomb compared to one with only a dud? And if yes, how does the bomb interact with the guiding wave? Because usually it is described as a pointlike device that only explodes when hit by the...

This question stems from one of the recent homework threads. I'm familiar with the derivation given here regarding mass accretion and ejection, where the general idea is to define a system around body and all of the incoming/leaving mass so that we can once again apply NII to the whole thing. I...

If a singularity exists in the center of a black hole, could quantum physics, instead of relativity , explain it?