# Bob_for_short

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344

## Posts posted by Bob_for_short

### Energy conservation problem

... these two scalar variables should interact.

That's my problem - to make them inetract. I do not know how.

### Temperatures at LHC collisons

Easily one trillion, closer to 4 trillion or about the temperature of a quark-gluon plasma. Not Planck length - that temperature would be >> 1026 K.

Do those quarks have time to have several collisions to thermalize? If yes, then this quark-gluon plasma is as a whole at rest and it should decay in all directions equally.

### Award for discovery of bare particles

As you know, positrons were predicted theoretically. They were necessary part of the theory and thus were supposed to exist.

Often they say that bare particles absorb infinities and this makes the theory work. Some say they are predicted by the theory.

I wonder whether somebody has ever been awarded for discovery of bare particles as such? Or this important discovery was left out?

### Energy conservation in Electrodynamics

Isn't that just the way it works? If the final charge velocity is not zero, then the initial wave train has less energy. It has done work and transferred momentum.

Yes, the incident wave-train can get weaker if it is accompanied with the radiated wave and the resulting wave amplitude (=> energy-momentum) becomes smaller. I just do not see it immediately.

### Energy conservation in Electrodynamics

EDIT: I can emit a half-period long wave from a radio-transmitter: $E(t)=E_0 sin(\Omega t), 0 < t < \pi/ \Omega$. Then the final charge velocity will be clearly different from zero:

$ma=F(t), v(t>\pi/ \Omega)=\int_{0}^{t}F(t')dt'=\frac{2qE_0}{m\Omega}$.

In addition, the charge itself radiates some new wave during acceleration period. The radiated energy is only a small fraction of $\frac{mv^2}{2}$. What can guarantee that the total energy remains the same?

### Energy conservation in Electrodynamics

No, it is not Compton. Just a regular electrodynamics problem.

How energy can change? Via destructive interference? How to show it?

### Energy conservation in Electrodynamics

Let us suppose that we have a known electromagnetic wave-train of finite size propagating in a certain direction. On its way there is a probe charge. This EMW is an external field for the charge. The EMW has a certain energy-momentum (integral over the space). After action on the probe charge the wave continues its way away. In the end we have the energy of the initial wave (displaced somewhere), the kinetic energy of the charge (hopefully it starts moving), and the energy of the radiated EMF. Thus the total energy is not conserved, is it?

### Unknown Physics of Particle Orbital Momentum

I submitted another note on unknown things in a well known domain; this time about the orbital momentum of particles in atoms. See http://www.science20.com/qed_reformulation_feasible/blog/unknown_physics_particle_orbital_momentum

First I made a conceptual error when put R=0, but later on I gave a detailed derivation to show where the error was admitted and why this was an error (see here).

### Explain Wave Function for a science starter

How to explain Wave function concepts to a High School student with bear knowledge of mathematics

It's easy. Any meaningful picture contains many points - pixels, if you like. So one point (pixel) is not sufficient to describe the picture of a complex thing. But we may construct this picture point by point, OK? Each point belongs to the whole picture but is insufficient to represent it. Now, the wave function squared is the whole picture and each separate, elementary quantum mechanical "measurement" is a pixel of the whole picture. The wave function does not collapse while measurement. On the contrary, each "elementary" measurement is the information bit retrieval, if you like, necessary for description of a complex thing.

### When Did Time Start?

According to the big bang theory time,matter and everything started in a split second but I don't understand something which is super heated ( something like 1 trillion trillion degrees Celsius ) and eventually it created a super blast which made the universe. I still don't understand how time could actually be 'created' because it's not like matter, because you can't get a hold of time,you can't grasp time.

I think that time wasn't actually created it was in existence before the big bang but that still doesn't answer the question,"How did time start?"

I am skeptic about big bang but time is very observable thing. It cannot be separated from matter. Ask experimentalist who monitor parameters. They use clocks. Time, if you like, is a periodic process with a sufficiently short period to label different stages of the observed transient to the required by you accuracy. Using time is using at least two different in "periods" physical processes: one is "slow" (a phenomenon being observed) and the other is "quick" (used as a clock).

### Fusing Particles and Wave function

We do not have many wave functions but one sole (total) that represents the occupation numbers of different states (particles). Particles are just excited states of this wave function. If there is no particle, the wave function is in it ground state.

On the other hand, the amplitudes of populations may be considered as "wave functions" of particular particles. It is these amplitudes that grow up and fade out in reactions. These amplitudes are responsible for probabilities of reactions. If a particular amplitude is equal to zero, it does not mean the total wave function is zero.

### Fusing Particles and Wave function

So if I have a proton and an electron, and they fuse to form a neutron, what happens to the prior wave functions? Is there some conservation of wave function law? Is there a mathematical process that shows how the wave function of two opposite charged particles change into one new wave function?

The prior wave functions fade out, the new one grows up. The easies way to see it is to consider the occupation numbers of different states. Occupation numbers change at a given total energy, momentum, angular momentum and maybe some other conserved quantities. Kind of balance equations.

### Photon creation

Isn't that a form of "De-excitation of an atomic or nuclear system?" This is interesting. I thought photons only formed through de-excitation of excited electrons at the atomic level. I didn't know that whole atoms/systems could generate radiation. It almost seems as if there is a friction-producing medium that the systems are moving in that causes them to lose momentum and radiate it out in the form of photons? Since "ether" has been rejected, could the medium be omnipresent EM field-force, or maybe gravitation? I don't know why I keep coming back to the question of a medium for light but at this point gravitational field-force seems like a candidate to me. Is there any reason why it can't/couldn't be the medium for light?

I do not think so. For example, a decaying "particle" is first entire and after a while it decomposes into pieces. No friction is necessary to describe it.

### Photon creation

De-excitation of an atomic or nuclear system, acceleration of a charge, matter/antimatter annihilation.

Or deceleration of rotational motion of a two-atomic molecule ;-)

### Spin

I find this subject interesting , yet at the heart of quantum theory. If anyone has any eureka feelings about " spin" at the quantum level please could you share them !

It represents spin as the energy flow of a wave packet of limited size around z-axis. However the spin does not depend on the packet size. Factually it is shown that a vector field has spin 1 and spinor field does 1/2. We knew this without wave packets.

### A Ring Around The Earth

And if instead of a ring you made a sphere?

Like clouds?

### A Ring Around The Earth

Okay this was just a random thought one day.. but think about this. If you were able to build a perfect ring around the earth, supported by beams, and then you took all the beams out at the same time. Would the ring float around the earth because of gravity? Or would it fall over, or spin around the earth??

Take a soccer ball and a rope and make a ring around the ball. Then add to the rope, say, 3 m extra and make a concentric ring around the ball. This longer ring will be at about 1 meter from the ball surface. In other words, the gap between the ball surface and the ring will be about 1 m.

Now make the same procedure with the Earth. The gap will be the same - about 1 m!

### There isn’t any experimental evidence to support special relativity!

There isn’t any experimental evidence to support special relativity!

Then you are unaware of the history of SR. It was a theoretical development by Lorentz, Poincaré, Einstein, Minkowski, etc., to describe the experimental data available at that moment. Read H. Poincaré who wrote articles and books, as well as gave presentations on this development and finally derived everything in his paper.

### question on transformer

If you connect the primary and the secondary circuits, you will obtain two primary (parallel or anti-parallel) circuits. Both need an external source of power supply to "operate".

If there is no an external source, the current in wires will decay due to Ohm resistance, radiative losses, and the heat released in the transformer core.

### Photon Polarization from Electro-dynamic Potential ?

...Look at one complete wavelength, starting from the left. There's an electromagnetic field variation here, but no charged particle present. ...

This is a graph of the electric force F(t) = q*E(t). Without a charge, there is no force to act on.

If you speak of the field E source, it is far away, an antenna, for example.

### Photon Polarization from Electro-dynamic Potential ?

Hi Widdekind, Bob. Can either of you explain the difference between A and V?

V is written upside down and does not have a "-" in the middle.

### Photon Polarization from Electro-dynamic Potential ?

Can you create a "scalar photon", w/o using an electro-dynamic potential (A), but only a time-varying electro-static potential (V) ?

Such a field exists indeed next to a vibrating dipole (along its axis) but this variable field does not propagate too far - it decays rapidly with the distance and is called a "near field". Anyway it's an axial (radial) electric field E = -grad(V).

### fields

I am not familiar with quasi-particles or microelectronics yet, so I do not know if you are accurately describing what I had in mind. would appreciate it if you elaborated your post.

Fields in any understanding are some entities that carry energy-momentum to be able to exchange it and be observable. Quasi-particles are described with specific quantum or classical fields. Each piece of matter has its own unique quasi-particles. In this sense their variety is enormous.

### fields

...But is it possible to synthesize a brand new field (even theoretically) not simply make a composition of existing attributes....

In solids there are quasi-particles with unique properties for different samples. They are studied and used in microelectronics.

### Monopole

Hm, that's an odd arrangement of charge. Getting the charge to switch from -kL to +kL at x=0 would be hard to do though. In any case, it is a mathematical construct and in reality your charges will be point sources rather than smooth....

True enough, but arbitrarily large charges arbitrarily close together is more mathematical than reality.

You are right, of course.

Let us return to the spherical magnet configuration. The radial magnetic field looks weird to me. Maybe one cannot get a complete cancellation of azimuthal fields inside and it will be something complex, with closed lines.

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