# Amr Morsi

Senior Members

272

1. ## Gravitational-wave Singularity

It is not a must to have a star collapse in order to produce gravitational waves. They can also be produced from 2 masses rotating around each others. In general, gravitational waves are produced from any accelerating mass....... very similar to electromagnetic waves. It is also to be noted that when a star collapse into a black hole, this doesn't imply a transformation to energy, but it is contraction of mass over space. By the way, simple spherically-symmetric contraction of stars or expansion doesn't emit gravit. waves, as stated by Einstein.
2. ## question

The R.H.S. of Eq. 2 is only a function in y, the rest are constants. So, differentiate it with respect to y, and then substitute a time with y=0 and another time with y=1/2. You will get 2 relations for the constants a'o and a'1/2 and thus get both in terms of ao. The same can be done with eq. 3. Merged post follows: Consecutive posts mergedI think you will have to integrate Eq.1 and T00 with respect to y in order to get rid of the delta function present in T00. Integrate it from -epsilon to +epsilon and thus some term in G00 will vanish and then substitute with the constants-relations you obtained previously. Merged post follows: Consecutive posts mergedIf Eq. 2 is NOT differentiable at y=0, try to integrate the equation following it(containing a''), it is the origin of Eq. 2...... It will be easy to evaluate.
3. ## Wave Functions are extended in time, too ??

If the potential is not a function of time (i.e. function of space only), then schrodinger equation will be solved by separation of variables, and the time function will be only a phase function (exp(-iE*t/hbar)). However, if the potential is function of time, then the solution will be more complicated and the maximum of the probability density function will be moving with time through space; which gives the analogy to motion in classical physics.
4. ## delta dirac propieties

For the former equation you wrote, integrate both sides and make the boundary conditions -Pi and phi. You will get 1+k*phi=T, i.e. phi=(T-1)/k. Merged post follows: Consecutive posts mergedSorry for this error. Make the boudary conditions phi and pi+epsilon. And, you will get 1+k*(pi - phi)=T.
5. ## What causes "Wave Function Collapse" ?

When you use a potential function in time (such as step up or step down) the schrodinger equation may give you a collapsed wave function or a generated one. But, in general, Schrodinger Equation gives stationary states when the potential energy (V) is not function in time, and the solution is obtained by SOV Method.
6. ## Maxwell's equations: meaning, derivation and applicability

1. The curl of the static gravitational field will not change with the velocity nor acceleration of the affected body but with those of the source mass, i.e. it will be dynamic gravitational field. This can be solved using General Relativity. 2. B® is solved in the attached file for the example you give, just put acceleration equal to zero. Exact B® is given and then approximation is made. Time retardation effects mean the properties of the charge at the time the radiations reach a position P...... It is not an approximation. - With respect to radiation; the electron gets accelerated from the external field, and some energy goes to the kinetic energy of the electron (and change in the direction of the velocity) and a small portion goes to the field radiation. - According to uniformly moving charges frame of reference, the magnetic field will be zero, as the charges will be considered motionless, only there will be electric field. Gauss's law for magnetism is an associated law (since the right hand side is zero), it helps in adding to the other laws that the magnetis flux lines are continuous.
7. ## Maxwell's equations: meaning, derivation and applicability

1. The curl of a static gravitational field is zero 2. To solve the example, thanks to refer to the attached file. chap14.pdf
8. ## electric attraction

But don't forget that ions do contain shells of negative electrons. And that is the reason they remain separated by a certain distance.
9. ## What does the energy of light depend on? Amplitude of the wave or frequency?

It may be helpful here ......... the power of light passing through unit area (with its direction) is equal to E x H; where E is the electric field intensity and H is the magnetic field intensity.
10. ## Maxwell's equations: meaning, derivation and applicability

Ambros........ it is important here to mention a Mathematical Theorem which states that any field vector is totally determined if its curl and divergence are both known. That's why we have 4 Maxwell's Equations; 2 for the Electric Field and another 2 for the Magnetic field ....... although the R.H.S.s of these equations are functions of the electric and magnetic fields themselves. The main problem is in solving these differential equations, and in some times they get solved by perturbation theory. In order to get rid of the curl, you get the curl of both sides of the equation and curl of the curl of a field vector gives the grad of the div of the vector minus the laplacian of that vector. By that I think I explained the 2 problems you are confused with; 1. Maxwell's equations are contradicting or not sufficient, 2. How to solve them?.
11. ## SR composition of velocities question

The resultant velocity vector has three components; x,y,z. Suppose that the relative motion of the frames is in the x-direction. Then; the x-component will be got from the transformation relations, and the y,z-components are same as in the original frame multiplied by a simple factor due to time dilation effects.
12. ## is light a probability wave?

We must not get confused between the particle wave of photons and the wave nature of light. The existance probability of photons gets applied on the emission of photons by the light source (charge or current), after that the photons are well distributed according to the emission probability density, and the electric and magnetic fields are defined.
13. ## photons

Energy, direction and phase can all be determined from the Quantum Electrodynamics Theory. It is to be noted that the direction is a probablistic one; i.e. under a great number of emissions the probability gets determined. ......... as far as I think.
14. ## Is the speed of light really constant?

When light moves in a matter, its overall velocity changes (i.e. including absorption of light by the atoms and emitting it), but its velocity from atom to atom is still the normal speed of light..... Just not to get confused.
15. ## Uncertainty and Time

Hi All, This is a widely spread wrong fact about Quantum Mechaincs since long ago. There do is a time operator. And, as already been mentioned in this thread; the hamiltonian itself is a time operator. It is only because idea adopters sometimes get so sticked to their idea and they get away facts conflicting with their ones. Thanks.
16. ## interpretations for QM

I think logic is all the time true, but true logic. When we speak about physics then we must compare with known (or trusted) facts and logics that have to do with physics. The main thing that is not accepted by some scientists in Copenhagen's Interpretation is that it cannot determine the result of one experiment (with knowing the initial conditions of the experiment). It is only speaking about probabilities without any certainty (WHICH INCLUDES HUP) in any result.
17. ## Hawking's Theory of Everything.

Hello All, Hawking's Theory of Everything, is only a frame work for the expected theories in thie field. For instance, he was confirming his ideas by the applying of units preservations ans same famous equations. He didn't introduce any equation. But, he proposed an expected some-what reasonable answers to questions in the modern science. But, protesters are much more than acceptors for his theory.
18. ## EM Polarizations

Hi Buddies, Have anyone any idea about the ranges of factors in which electromagnetic polarizations, in waveguides, have a considerable effect in propagation of EM waves; material and designal ones? I am just doing a research in that issue to help in advance. Thanks.
19. ## Electromagnetic Engineering

Electromagnetic Books, I am just asking here, what is the most book used now in Electromagnetics and Wave Guides. Is there any book that treats special waveguides from QFT, or even semi-QFT point of view? Thanks for support, in advance.

Hi all, What about programming? These days they are very rare that works in programming! I even failed to get any successful connection through the internet to buy a VB.Net Compiler. Does anyone know why?
21. ## Cosomological Constant

Hi All, Some news are being transmitted now, that the cosomological constant, these time in the Universe, is passing through an abrupt change in value. Have anyone have any idea about that? Thanks in advance.
22. ## interpretations for QM

Regards, What is now mainly adopted with science and scientists is the Compenhagen Interpretations (Born Interpretations). The matter of relation between reality and observation, although being a vital issue, is not the main difference between various trends. It is the meaning of the wave function, mainly the squared modulus of the wave function. A serious trend now in the field of science, is adopting another interpretation, as previously mentioned in that thread. It is related to probability meaning of QM, and QFT. Not a few facts supports the new interpretation, which coincides with Schrodinger's Proposition: That it is the average effect of not-precisely known fundamental facts. You can refer to Schrodinger's Papers about that. I am just introducing a fact. Thanks for accepting it friendly.
23. ## Muscles and Physiology

Hi All, I was just wondering: Are Tendons' connections to the end of bones can endure these heavy loads that we carry? Or, that connections are through the length of the bones! Any help? Thanks in advance.
24. ## About interpretations and logic...

Hi Sir, With respect to the twin paradox, it can totally be accounted for by the Special Relativity, even though acceleration is involved (can be included in SR, as opposite to many people may think). Science now has settled down to that the traveller (accelerating and decelerating) is the younger. But, I can say with confidence, other serious deeper researches say that they will be equal in age, after accounting correctly for acceleration in SR. A simple check, look to the other twin from the versus-frame-of-reference. What is the situation? It is totally the opposite. Buddy, Time Transfer is only accounted for in GR, WHERE MASSES ARE AFFECTING THE SPACE-TIME CURVATURE. May be I pointed it out. But, I studied it and Experimentally.
25. ## Where Does Space End? It Must End Somewhere!

Hi All, I am wondering if Space is to end somewhere, then what will be after that "somewhere"?
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