Origin Definition and 651 Threads

If we had a literal two body system (point masses M and m), with one orbiting the other according to Newton's Law of gravitation, would there be orbital precession? Or would they map out the same ellipse each time?

Scientists suggest that there was nothing before the Big Bang. Nothing. Seems to me, the fact that the whole universe came from nothing makes no sense. I know that there isn't an answer yet but I would like to hear what others might think about this issue

What is the origin of friction on the atomic (sub-atomic) scale?

In the diagram let the magnitude of the vector BC and OA are 'x'. I am confused with this part. Vectorially we don't say that the vector BC is ##-x##, because ##-x## is represented by OA. Then how do we represent BC? It's said a the position of a vector doesn't matter, I mean one can shift it...

The brains at the Perimeter Institute recently published a paper describing how our 3 dimensional universe could possibly exist as the event horizon of a 4 dimensional black hole in a 4 dimensional universe as the event horizons of black holes have one less dimension than the black hole itself...

Homework Statement Find the torque at point (1,5,2), first with respect to the origin and then with respect to the y-axis. F=2i-3j+k Homework Equations T=r x F The Attempt at a Solution Torigin= 11i+3j-13k ; Tyaxis=6i+3j-3k here I defined a new vector r'=1i+2k What I don't...

Dear all, This definition/property was given as a remark in my lecture notes. And I have attempted to prove it (I have attached the picture of proof). Can you please tell me if I am correct or wrong (& possibly where am I wrong?) Thanks in advance.

Homework Statement An alpha particle (the nucleus of a helium atom) is at rest at the origin of a Cartesian coordinate system. A proton is moving with a velocity of v towards the alpha particle in the xˆ direction. If the proton is initially far enough away to have no potential energy, how...

http://physicsworld.com/cws/article/news/2014/sep/02/big-bang-ruled-out-as-origin-of-lithium-6 The hystory of BB nucleosynthesis is quite busy, Gamow et al. started postulating that all elements were originated in the BB nucleosynthesis process in the late 40s early 50s, it soon became quite...

http://arxiv.org/abs/1409.2510 Twistor Origin of the Superstring Nathan Berkovits (ICTP-SAIFR/IFT-UNESP, Sao Paulo) (Submitted on 8 Sep 2014) After introducing a d=10 pure spinor λα, the Virasoro constraint ∂xm∂xm=0 can be replaced by the twistor-like constraint ∂xm(γmλ)α=0. Quantizing this...

Homework Statement Given the function f(x_1,x_2) = (x_1 - x_2^2)(x_1 - px_2^2) where p is a constant parameter, for what value of p will the origin (0,0) be a singular point of this function? Homework Equations The Attempt at a Solution I thought that singular meant...

So I have been reading about the nature of gravity, and I have become a little confused as to how gravity is produced. In some videos and books, they state that it is the mass of an object that generates gravity. However, others say that it's not so much as mass, but the density of energy/mass...

If you have a momentum integral over the product of propagators of the form \frac{1}{k_o^2-E_k^2+i\epsilon} , why are there divergences associated with setting m=0? Factoring you get: \frac{1}{k_o^2-E_k^2+i\epsilon}=\frac{1}{(k_o-E_k+i\epsilon) (k_o+E_k-i\epsilon)} . This expression has...

Homework Statement The formula is w(object)/F(buoy) = [density(object) * V * g] / [density (fluid) * V * g] = [density(object)] / [density(fluid)] This is way I thought they did it: w(object) = F(buoy) w(object) / F(buoy) = 1 --- Vsub/V = density(object) / density(fluid)...

I've been reviewing the timeline of the big bang... http://en.wikipedia.org/wiki/Chronology_of_the_universe http://en.wikipedia.org/wiki/Graphical_timeline_of_the_Big_Bang ...and wasn't able to find an answer to a question I have. That question is, is there any evidence that the...

Homework Statement At time t=0, a block is released from point O on the slope shown in the figure. The block accelerates down the slope, overcoming sliding friction. a.) Choose axes 0xy as shown, and solve the equation ##\Sigma F = m a## into its x and y components. Hence find the block's...

According to the Poincare recurrence theorem - certain systems will, after a sufficiently long but finite time, return to a state very close to the initial state. and according to wikipedia - a quantum fluctuation or vacuum fluctuation is the temporary change in the amount of energy in a...

In chapter 2.2 of Feynman's book on QFT, he states that the probability amplitude of a particle going from a to b is the sum of contributions from all paths, and that each path contributes the same amplitude, but with a different phase. My question is, why does Feynman state that this is the...

As we know Biot-Savart law follows right-hand rule, like this: ...so the question is why right-hand rule, why not left? I suppose it must have something to do with electron's magnetic dipole moment or "spin", as that's the only source of asymmetry I am aware of in this scenario. It...

Homework Statement Hello all. I'm currently attempting to prove the central limit theorem using a simple case of two uniformly distributed random variables. Aside from being able to solve it using convolutions, I also wish to solve it by using the Dirac Delta function. That aside, the integral...

Hi - wondering if you can help me find a solution of: \nabla^{2}u-\frac{u}{\lambda^{2}}=a\delta(r) for spherical symmetry in 3D with the condition that \lim_{r\rightarrow \infty}u=0. It can be rewritten in spherical coordinates as \frac{1}{r^{2}}\frac{\partial}{\partial...

Why did Verlinde in his paper suggest that information is a central concept in the emergence of gravity? I mean why information and not something else?

1.)Two charges are fixed in location: charge q1= +8e is located at the origin and charge q2= -2e is located on the x-axis at x=L. At what point can a proton be placed so that it has net zero force acting on it? 2.)F=kq1q2/r^2 3.)I tried to do F=0 K = 8.988 X 10^9 (constant) q1 = (8...

Homework Statement Calculate the charge and electric field at the origin of non-uniform line of charge on the x-axis from -10cm to 10 cm on the x-axis. Where linear charge density is given by 2x^4 Homework Equations dq=lambda dx de=(k dq)/r^2 E=integral of (Kdq)/r^2 = k integral of (lambda...

Given an ideal rocket in a friction-free, gravity-free environment: A precise amount of energy E is applied to accelerating a rocket. An external observer at the origin (rocket velocity=0) watches the rocket accelerate to a final velocity V. As expected, the origin observer finds that V...

Homework Statement Imagine a particle tracing a counter-clockwise circular path on a flat table with a certain speed. The particle is tied with a massless string of length R to a point P at the center of the circular path. Will the particle rotate about P forever at constant speed in the...

Does the tension force in elastic springs and strings arise inevitably as a consequence of Newton's third law? Or is it due to the electrostatic forces within the material itself? Or are both of these explanations basically the same thing?

Homework Statement a 20 kg sphere is at the origin and a 10 kg sphere is at (x,y) = (20,0). at what point or points could you place a small mass such that the net gravitational force on it due to the spheres is zero? Homework Equations g=GM/r^2 The Attempt at a Solution Can not...

Find the curve coordinates of the point nearest to P in the curve 2y2 = 5(x+1) P(0,0) Book answer (-1,0) ok (x-0)2+ (y-0)2 = D D = (x)2+ (y)2 and (y)2 = -x2 Now -x2 = 5/2(x+1) But derivating I don't get the answer or ansa

Homework Statement Say that P is a point on the surface xyz=8. Is it true or false that you can always find another point Q on the surface such that Q is further away from the origin than P is? Homework Equations ∇f(x,y,z)=λ∇g(x,y,z) where ∇g=0 The Attempt at a Solution Let...

Is there any explanation about the nature of electric charge? Everyon currently knows that an electric charge has ability to generate force and an electromagnetic field. Also, it has attractive and repulsive reactions to other charged particles. Finally, it is known that electric charges obey...

Hi I am working on a robot that has a spinning 3D laser scanner. It rotates about two axis and collects data. In one axis it has full 3D rotation and in another axis it has limit rotation. Now the read world points collect by this laser scanner is not unifomaly distributed but if...

Homework Statement A charge + q is fixed at each of the two points (±a,0,0). Show that the potential V at a point (x,y,z) near to the origin may be expressed as V = [q/4∏*ε*a] [[2+(2x2-y2-z2)/a2] where x, y and z are small compared with a. Homework Equations V(x) = q/4∏i*ε*r ...

Had this question on a test today, Find the shortest distance from the origin to the surface xyz2=2 I figured out by intuition that the shortest line between the origin to the surface will also be normal to the surface. I haven't done much of these functions in 3 variables, I read somewhere...

I'm doing a little research on quarks on stumbled upon the baryon number. Wikipedia says that the notion predates the quark model. I have no clue why particle physicists were motivated to introduce it before flavour quantum numbers came to the scene. So... What's the (historical) origin of...

Hi, so i have a fairly good understanding of most of the concepts relating to inertia. but my question is what is the force felt by the observer while accelerating. for example the force gravity can be described as space bending into shapes around the body of mass, the other can be described as...

Could you please help me by suggesting some books that tell the story of how "stuff" ( I mean the stuff we discuss in physics ) such as origin of matter from a universe with nothing but energy, origins of wave, gravity, electromagnetic forces etc in the course of the evolution of cosmos after...

The problem asks to find the standard matrix for the composition of these two linear operations on R2. - A reflection about the line y=x, followed by a rotation counterclockwise of 60o. This is how I proceeded. y=x $\begin{bmatrix}0&1\\1&0 \end{bmatrix}$ counter clockwise 60degs...

Here is the question: I have posted a link there to this thread so the OP can see my work.

Origin of the term "chair" in academia? When I was very young, I wondered why professors (heads of departments) were said to have a "chair" in such-and-such subject. I thought of the story about King Louis XIV of France who was said to have a chair in (their equivalent of) the cabinet room...

What is Schwinger terms that related with commutator of currents and what is the origin?Why the infinities appear when we consider the product of operators of fields at the same spacetime point?

Homework Statement Spherical Ball centered at origin uniform ##\rho## with a radius a. Find E along x-axis. Homework Equations ##E = \frac{\rho}{4\pi\epsilon_0}\int\int\int\frac{r^2*sin\theta}{r_\rho^2} d\phi d\theta dr## The Attempt at a Solution Evaluate E spherically along the...

Suppose we have some object with angular momenta \mathbf{L}_1 about rotation center O_1 and we have another object with angular momentum \mathbf{L}^\prime_2 about rotation center O_2. O_2 has some velocity \mathbf{v}_2 relative to O_1. Then we wonder what is the angular momentum of the second...

Gauge Principle is successful in strong electroweak force modeling in the the form U(1), SU(2), SU(3) and in GR but it fails in SU(5) or attempted gauge symmetry between leptons and quarks, it fails in Supersymmetry, fails in Supergravity, and even fails in String Theory. Don't we even know...

Find the rate of change of the distance between the origin and a moving point on the graph of $$y=\sin{x} \text{ if } \frac{dx}{dt}=\frac{2 \text{cm}}{\text {sec}}$$

My book has a discussion of how the Bragg model can explain the origin of energy band gaps in solid. I have attached the relevant part of this discussion. I would very much like if someone could help me understand what it's basically trying to say. Facts: 1) In the free electron model, the...

Homework Statement A charge Q is placed at the center of the origin on the attached document. What is the force on this charge? Homework Equations Coulomb's Law: F= kqQ/d2 ^ r The Attempt at a Solution See attached document for figure. I'm...

Ok, there are a couple of other threads about this, but they don't seem to answer my question. If I take the double derivative of 1/r, I'll get 2/r^3, but if I take the laplacian, I get something different. Why? Namely: \frac{d}{dr}\frac{d}{dr}(\frac{1}{r}) = \frac{d}{dr}...

Homework Statement Calculating the horizontal component of an electric field at the origin of a semi circle. The image link is: http://imgur.com/SXYs4Rp The Attempt at a Solution I've tried using the formula k∏(Q)/r (8.98755*10^9)∏(-7.85*10^-6) / .113 = -1.961 * 10^6. Can anyone see...

The line L passes through the origin and is parallel to the vector 2i + 3j. Write down a vector equation for L. $$r=(0,0)+s(2,3)$$ my question pending this is correct, could this be written as: $$L=s(2,3)$$:confused: