Origin Definition and 651 Threads

I learn that we can expand the electric potential in an infinite series of rho and cos(n*phi) when solving the Laplace equation in polar coordinates. The problem I want to consider is the expansion for the potential due to a 2D line dipole (two infinitely-long line charge separated by a small...

The great basic question of science: Membrane compartment or non-membrane phase compartment (biophase) is a physical basis for origin of life? Matveev V.V. 2016. Comparison of fundamental physical properties of the model cells (protocells) and the living cells reveals the need in...

Novel idea on the origin of life based on a system self organizing to dissipate energy as efficiently as possible: http://www.businessinsider.com/physicist-has-a-groundbreaking-idea-about-why-life-exists-2016-1?amp

Hi guys, I have a very very simple and naive question, which I hope I shouldn't be ashamed to ask, but I would like to clarify an issue in my mind. We hear everywhere that the value of the ew vacuum is v ~ 246GeV, fixed by the Fermi Constant G_F, v = (\sqrt(2)*G_F)^(-1/2). Now this is also the...

In 2008, astronomers discovered that a multi-million-solar-mass cloud named Smith's Cloud would hit the Milky Way's disk in about 27 million years. Now new Hubble observations have identified the mysterious cloud's likely origin. Link: New Scientist

Why is rotational equilibrium condition independent of origin about which torques are taken?

For a circle with radius R centered at R along the X-axis so that the edge of the circle touches the origin, what is the length of a line drawn between the origin and an edge of the circle in terms of the angle between that line and the X-axis? This isn't a homework problem, just something I'm...

So, I've heard from several people that Origin is used as a spreadsheet alternative in the scientific community. It seems to be a proprietary software (baah) and I couldn't find anything about a native linux solution so I ask: Do you use Origin in Linux? If so, how do you do it? Wine? VM?

As I understand it a coordinate origin is just chosen for convenience. So how can we state the Earth revolves around the sun when you could make coordinate origin at any point in the universe??

Homework Statement Acceleration of a particle that begins at rest at the origin is given by a(t)=3ti+4tj, where a is in m/s^2 and t is in seconds. The particle's distance from the origin at time t=2s is what? Homework Equations You need to find velocity then distance The Attempt at a Solution...

So, it always (at least in the books that I have read or scanned) that the Einstein-Hilbert action $$S=\int{\sqrt{g}d^4xR}$$ is directly posed without an explanation of its origin. My question is how did it occur to Hilbert or Einstein to write down this specific form of action?

Homework Statement Solve the poisson eq. on R with a source in x=0. The Attempt at a Solution I haven't done this kind of thing in years, so I'm a bit rusty, but I think that this is requested: \Delta \phi = - \rho \delta(x) (Edit: no wait, I need an integral here). It doesn't seem to be...

On reading this thread: https://www.physicsforums.com/threads/Newtons-law-of-gravitation.835627/ I started to wonder (not for the first time) when (and where?) the term "subject" became common, for the variable on the left side of an equation or formula? I'm pretty sure nobody talked about...

Homework Statement a) and b) are no problem. I need help to solve c) and d) Homework Equations c) Delta dirac function Gauss' law d) Gauss' law ## \int_V {\rho \, d\tau} = Q_{enclosed} ## The Attempt at a Solution By taking laplace on the potential I get: ## \rho(\mathbf{r}) =...

In Griffiths, it seems that the conceptual introduction of the magnetic vector potential to electrodynamics was justified based on the fact that the divergence of a curl is zero; so we can define a magnetic field as the curl of another vector A and still maintain consistency with Maxwell's...

Homework Statement Find the distance between the origin and the line tangent to ##x^\frac{2}{3}+y^{\frac{2}{3}}=a^{\frac{2}{3}}## at the point P(x,y) Homework Equations [/B] Distance= ##\frac{\left |a_{0}+b_{0}+c \right |}{\sqrt{a^{2}+b^{2}}}## The Attempt at a Solution To begin I find...

Homework Statement In this note , I was told that either vector OD , OC , AD and AC can be used as the distance between the Force and OA axis ... why ? To produce moment , the distance r must be originate from the origin of force ( point C ) , am i right ? So , IMO, only r AC can be used...

Homework Statement When an object is submerged or floats in a fluid, the.. Pressure on bottom surface > Pressure on top surface So the resultant force is acting upwards. Why the difference in pressure? Must both, the top and bottom surfaces, have the same area of contact with the fluid? Since...

There's a new paper by Barbour on Arvix, "Entropy and the Typicality of Universes". It's not about an oscillatory model, but, per remarks that include note 18 on its p.10, it puts the transition from an expanding to a contracting phase, characteristic of such models, into the spacetime center...

I know gravity is a conservative force field and can be treated as such for all intents and purposes, but I was just thinking that in order to show that a vector field is conservative that vector field must be defined everywhere (gravitational force field is not defined at r=0). I was thinking...

Homework Statement A boat is sailing starting from x = 200m. When interpreting x(position) vs. t(time) graph for this boat with math models x = -20t + 200(t<=10), Is it right to say "The boat is approaching to the origin" ? (When t <= 10) Homework Equations x = -20t + 200(t<=10) The...

Hi, I'm trying to write the current density for such circular loop in spherical coordinates. For a circular loop of radius a that lies in the XY plane at the origin, the current density it's simply: \mathbf{J}= \frac{I}{2\pi\sin\theta}\delta(\theta-\frac{\pi}{2})\frac{\delta(r-a)}{a}\hat{\phi}...

are there any books on the origin of life.. AstroNeil

Homework Statement determine whether the graph of the function has symmetry about the x-axis, the y-axis or the origin. Check work by graphing: x^(2/3) + y^(2/3) = 1 Homework EquationsThe Attempt at a Solution [ x^(2/3) + y^(2/3) = 1 ] ^(3/2) y = -x+1 Its a straight line with y-intercept at...

So I have been looking around throughout the physics forum and other sources and still can't seem to find a good general explanation of how Life, and energy are related. First let me propose some definitions to help further our discussion and clarify what i mean. Life, in the way it concerns us...

I just watched a popular science program entitled Super Massive Black holes that proposed the idea that galaxies were formed long ago from hydrogen gas clouds whose centers collapsed to become super massive black holes that then generated star formation and ultimately the formation of galaxies...

Homework Statement An important result in the theory of antennas, is that if a current passes through the ZZ axis, the magnetic field far from the origin can be expressed in spherical coordinates, using only one componente of the magnetic vector potential. Prove that: Homework Equations The...

what is the origin of the number of bound (N z /2 ) in the calculating of average in ensemble in Mean Field for the Ising model?

Homework Statement Find the potential of the point in the origin in regard to referring point at infinity if there's charged line laying on x-axis as shown in the picture. Homework EquationsThe Attempt at a Solution I know two ways to find a potential: V=∫dV and V=∫E*dl using first...

Homework Statement A positive charge Q is fixed to the origin. A negative charge with magnitude 9Q is fixed along the positive x-axis a distance d to the right of the origin. Determine a point where a small positive test charge q will experience zero electrical force from the two charges, or...

Homework Statement Hello, I just started my summer class "Applied Linear Algebra I" Last math class of my under-grad and its been 1 year since I've last taken Calc3, so I'm trying my best to get back into the groove...anyways. Our first topic we are discussing in class is vectors. [1] This...

from mpl_toolkits.mplot3d import Axes3D import matplotlib import numpy as np from matplotlib import cm from matplotlib import pyplot as plt import numpy as np import matplotlib.pylab as plt import math import random from scipy import integrate step = 0.1 maxval = 1.0 fig = plt.figure() ax =...

Homework Statement I have to find a electric field vector and a potential of the point in the origin of the x0y coordinate system (0,0) due to a longitudinal charge placed on a half circle as shown in the picture, with radius a. Homework Equations Coulombs law. The Attempt at a Solution...

I understand that the interaction with the Higgs field (Higgs Bosons) confers mass to elementary particles such as the electron. Does that mean that interaction with an electromagnetic field (photons) confers charge to electrons? If not, what is the origin of charge? Also, how is it that the...

Homework Statement a point particle is located in the position r=i+2j m . A gravitation (vertical) force of 1.5N acts on the particle. The torque about the origin is... Homework Equations thau = r X F = rFsin(theta) The Attempt at a Solution it's 0 right? magnitude r = sqrt(1^2+2^2)m...

Homework Statement Negative charge -Q is distributed uniformly around a quarter-circle of radius a that lies in the first quadrant, with the center of curvature at the origin. Find the x- and y-components of the net electric field at the origin. Homework Equations V = ∫kdQ/r Eradial = -dV/dr...

Homework Statement A +20nC point charge is placed on the x-axis at x = 2.0 m, and a -25 nC point charge is placed on the y-axis at y= -3.0 m. What is the angle that the direction of the electric field at the origin makes with the x-axis. (a) 209 (deg) (b) 61 (deg) (c) 29 (deg) (d) 241(deg) (e)...

Dear All,I understand that one of the most popular theories concerning the origin of the solar system begins with cloud of gas and dust (called a nebula), assumed to be the remnants of a supernova; in order to explain elements such as iron and above.That this nebula begins to flatten into a...

Hello, I'm was going through the simple harmonic oscillator, just as a recap, and I stumbled upon something which is causing me wonder. I'm solving the SHO with a shifted origin, and so I have the differential equation F=-k(x-x_0) \ddot{x}=-\frac{k}{m}x+\frac{kx_0}{m} Now, I get that I can...

I have seen in many places, for example here, the statement that the proton consists of valence quarks and sea quarks. I am somewhat confused as to where this picture comes from. The sea quarks are virtual quark-antiquark pairs. I have encountered virtual particles only in the context of...

Almost always in xy plane we take that origin is ##(0,0)##. Is it possible to take that origin is in the point ##(1,1)##, or some other point?

Hello. Standard Model is based on the lagrangian of the dirac equation where some gauge group are applied. But, i am asking me, why a field is used before it was created. Properties of particle come from the application of Noether Théorem and then a quantization. I imagine the same process for...

At the superconductor-superconductor point contact regime, two Andreev bound states carries supercurrent through the S-weak links-S interface. According to literature, current can be simply expressd Eq1) I_S=(1/Phi_0)*dE_A/d Phi here I_S : supercurrent, Phi_0 = flux quantum, E_A : Andreev bound...

I'm a maker of concert-tuned transverse ocarinas, which are a kind of Helmholtz resonator, however that does not tell the whole story as they are driven with an air-reed. This set up seems to differ from what is defined by the Helmholtz resonator equation in that it does not have a single...

A vast ring of dust may explain the star-generating nebula’s birth. Full story (including a color image of the new dust ring, which is 330 light-years across): Scientific American.

Dear users, I deal with following problem. I've got a data of Intenzity of chemiluminezcence as a function of temperature. The data should be fitted by following equation: I found that in origin one can fit also data with integral function, with fittin parameters P, A, i, E. The beta and...

According to my book, if we write the equation of a plane as: ##ax + by + cz = d## And two planes have values of ##d## with the same sign, they are on the same side of the origin. If they have values of ##d## with different signs, they are on opposite sides of the origin. I'm confused as to...

Is an eternal and dynamic universe the only sensible universe? I mean clearly creation ex nihilo is absurd, so either reality is inherently absurd or its eternal, mechanical, and logical with no clear "beginning".

I am having a personal discussion with somebody elsewhere (not on Physics Forums) and we are stuck at the moment because of a disagreement that I narrowed down to the question whether, in the context of SR, two observers in different reference frames can choose the origin of their coordinate...

Hello! I am not sure if this is the correct place for this but here is a go. I'm currently applying to graduate schools and I know that I am interested in theoretical particle physics and condensed matter theory. In electricity and magnetism we were told that charge is an axiom and it's not...