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Link to thread of next article. 2 black holes to 1 + radiation. Can the time reverse happen? Date: 1995/09/05
Two black holes collide and give off radiation, in principle can a black hole be subject to gravitational radiation and then become two black holes?
Link to thread of next article. QED ? Date: 1995/09/06
Is it true that if one describes an electron in QED one must in effect use a mass much larger then that of the electron for the term in the Lagrangian which describes the energy due to just the rest mass and kinetic energy of the electron, and only when an interaction term is added to the lagrangian and calculations done does the effect of an electron emitting and reabsorbing virtual photons cancel most of the very large input mass?
If this is true, can you give me a hand-waving argument as to why an electron emitting and reabsorbing virtual photons reduces its' mass? Is it as simple as a particle which emits something must then be less then it was before it emitted something and in this way spends some of its time being less then itself?
Link to thread of next article. String question. Big things from small strings? Date: 1995/09/06
Assume as de Broglie did that there is a fundamental frequency associated with an elementary particle given by mc^2=hv.
From the little I know of string theory, elementary particles are described as very little loops (10E-35 m) which trace out "tubes" in spacetime, and with some extra curled-up, undetected dimensions for magic (any good hand-waving arguments as to why six extra dimensions and not say seven in some theories?).
Now for my question, it may not make sense, in which case my apologies. How can one get relatively small frequencies (mc^2=hv --> v=mc^2/h=1.2E21/s here m is the mass of an electron) from the structure of string theory when the fundamental length of string theory together with the speed of light give you a much higher frequency (v=(approximately) (3E8 m/s)/10E-35 m=3E43). My only guess (what's yours) is that there are two or more very high but nearly equal fundamental frequencies that come from the string idea whose sum gives a much lower beat frequency =v=mc^2/h. (The bare mass of an electron is almost infinite? --> one large frequency, the correction to the bare mass is also almost infinite gives another large frequency?)
Link to thread of next article. "Energy" in Gravitational wave. 2nd try. Date: 1995/09/08
A plane electromagnetic traveling wave can be thought of as half the energy of the wave in the electric field and the other half in the magnetic field. Can such a division be made with a plane gravitational traveling wave? The reason for my question. A standing electromagnetic wave alternates between all electric field at one instant and at some latter instant all magnetic field. A plane gravitational standing wave will have at one instant maximum tidal fields and at some latter instant the tidal fields will be zero (think I'm right on this). While the tidal fields will be zero their change in time will be maximum. Is this some kind of field where energy is stored? I'd like to think of spacetime as elastic where energy can appear as potential energy of stretched elastic or as kinetic energy of elastic in motion. Am I far off?
Link to thread of next article. Given one, what physics question would you ask God? Date: 1995/10/13
In Dec 1989 Physics Today, page 9, David Gross wrote "...One of the best of the many Pauli jokes tells of Pauli's arriving in Heaven and being given, as befits a theoretical physicist, an appointment with God. When granted the customary free wish, he requests that God explain to him why the value of the fine-structure constant, alpha = e^2/(hbar*c), which measures the strength of the electric force, is 0.00729735 .... God goes to the blackboards and starts to write furiously. Pauli watches with pleasure but soon starts shaking his head violently...."
Latter in the article David Gross gives reasons that physicists nowadays might ask instead "why are there three generations of quarks and leptons" or "why does the cosmological constant vanish" or "why is space-time four dimensional"
In a neat little book by Feynman, The Strange Theory of Light and Matter, page 129, he writes "It [the fine-structure constant] has been a mystery ever since it was discovered more than fifty years ago, and all good theoretical physicists put this number up on their wall and worry about it."
"It's one of the greatest damn mysteries of physics: a magic number that comes to us with no understanding by man."
Somewhere Wheeler says we should find out "the reason for the quanta", though I'm not quite sure what he meant by that.
Somewhere Einstein says something like "for fifty years I have been brooding about what is a photon but still have not a clue". I would guess he would ask God something like "what" is a photon.
I would ask God if he knows where an electron will go once it scatters off a crystal, then I would ask Feynman what God told him about the fine-structure constant.
Easy to show how spin of boson field effects attraction vs. repulsion. Date: 1995/11/07
Gravitons are spin 2 and therefore(would like to show this) like charges(mass) attract each other. Photons are spin one and therefore(would like also to show) like charges repel. I have seen this in many places, that even spin bosons give rise to attractive forces between likes and odd spin bosons gives rise to repulsive forces between like charges. Any help in understanding this fact would be greatly appreciated.
While I have your attention, if the graviton corresponds to a 2nd rank tensor field would a spin n boson field correspond to a nth rank tensor field?
What would these higher rank fields be like roughly? Would massless spin n bosons still have only two polarization states?
If photons had a small mass then we go from two polarization states to three? Would we then have longitudinal photons?
Is the timelike photon still absent?
What would a classical E&M wave of longitudinal photons look like? The electric vector parallel to the propagation vector?
What would a classical E&M wave of timelike photons look like? Ripples of charge density which would violate charge conservation?
Feynman Lectures on Gravitation and the photon mass. Date: 1995/11/11
I must share an answer to a question I have had, the answer to which I came across in a new book "Feynman Lectures on Gravitation". Now that I see how easy the solution is I feel stupid for not solving the problem myself.
My question. Use the fact that earth's magnetic field extends out several earth radii to place a very small limit on the mass of a photon.
The answer is on pages 22 and 23 of Feynman's book. Feynman uses three examples to prove the mass of a photon is less then 10e-9, 10e-15, and 10e-20 electron masses.
Proof for 10e-9, given w=(k^2+m^2)^.5 the energy frequency relationship of a massive photon, then red light would be slower then blue light from eclipsing double stars, that is when one star blocked the light from the other the last blue and red photon headed for the earth would not reach the earth at the same time. We would see the star go from white to red. And when the star first appeared it would go from blue to white( for a white hot star).
Proof for 10e-15, the behavior of long wavelength photons are most effected by a small rest mass, and from the known sharpness of pulses of reflected radar waves the limit follows.
Proof for 10e-20, if the photon had a rest mass m, then fields would fall off as exp(-mr)/r, and given the earths magnetic field extends several earth radii the limit follows.
Barrow or buy the book!
Re: NATURE, 12 Oct, quasars are not black holes. Date: 1995/11/13
In article <48664v$pqj@dartvax.dartmouth.edu> Archimedes.Plutonium@dartmouth.edu (Archimedes Plutonium) writes:
Some cool stuff, deleted.
This raises a question? Instead of a billion solar mass black hole in a galaxy would not one billion, one solar mass black holes be more efficient at turning matter into energy? I guess the question is, is such a structure stable?
Re: Gravity wave propagation. Date: 1995/11/28
In article <49f0fc$140b@sat.ipp-garching.mpg.de> bds@ipp-garching.mpg.de (Bruce Scott TOK ) writes:
> Erik Max Francis (max@alcyone.darkside.com) wrote: > : bds@ipp-garching.mpg.de (Bruce Scott TOK ) writes: > > : > No. Light waves only do that in the averaged model in which the > : > continuous absorption and re-emission process is not being followed. If > : > you follow the micro-physics of matter (as we do in a plasma, usually), > : > then light travels at c also within matter (between interactions). > > : This I knew . . . but would the average speed of the gravitational > : wave be slowed due to interaction with matter? If it would, how would > : the amount of slowdown relate to the matter's physical properties? > : Would there be something like a kind of gravitational wave refraction > : index (although, I would suspect, considerably more complicated)? > > Actually, it is probably more fundamental than I indicated: you need a > polarization phenomenon to get the slowing down in EM (in which you also > get screening). This comes about due to charge separation
So the GR analog of charge separation is tidal distortion. The earth has a fundamental mode of vibration which can be excited by gravitational radiation. Let gravitational radiation scatter from the earth. If the driving frequency is smaller, or larger then the earth's natural frequency then the phase of the gravitational wave will not be in step with the radiation the earth reradiates. This is just the same effect as with E&M radiation interacting with charged matter?
Link to thread of next article. Do elementary particles have mass? Date: 1995/11/28
Vertern Vergon suggests light has mass because a photon can "turn" into an electron-positron pair (hope I have his argument right)?
Can this be turned around. I would like to think that in a rough way electrons and positrons and other particles with rest mass are in fact made up of stuff which moves at light speed, so there is no rest mass at the finest scales, everything is moving at light speed?
Re: Do elementary particles have mass? Date: 1995/11/30
In article <meeuwiss.17.004E5BA3@natlab.research.philips.com> meeuwiss@natlab.research.philips.com (Meeuwissen, M. GST) writes:
> In article <49itba$b4q@hearst.cac.psu.edu> ale2@psu.edu (ale2) writes: > >From: ale2@psu.edu (ale2) > >Subject: Re: Do elementary particles have mass? > >Date: 30 Nov 1995 00:19:54 GMT > > >> > >> So: No, photons don't have mass, at least NOT BECAUSE an electron-postitron > >> pair has mass. > >> > >> Elementary particles can have mass, > > > >At this point I was hoping for some semi-wild speculation as to what > >an electron "really" is. Why can't it be a "massless dog chasing its > >tail". > > Hmm, you mean: "Why can a massless particle not run in very small circles? > Then it still moves at light speed on a microscopic scale." > I cannot think of an argument quickly why this isn't a valid view. It does > however seem to be very unQM. Which force will keep it in orbit? How to > describe its inertia? > > I like to think of > electrons as nothing more as a charged and massed point-particle (on large > scales). Or as a wavefunction which describes all of its properties (like > position, velocity, charge, spin). That for me is "really" an electron. Why > searching a more classical, mechanical description of it? > > >Just trolling for some wild ideas that might be in the back of V.V.'s > >or Abian's or your head. > > Wild ideas I reserve for things I don't understand at all (and even then, it's > better to consult someone who does). By the way, I think the current, QM > description of an electron is wild enough already.
When someone figures out why electrons come in little packets of charge and mass will we say "oh, I should of thought of that, how simple" or will it be somewhat more complicated?
Since we have no idea at the present, string theory excluded, some semi-wild educated speculation might be in order.
Looking for a spark to ignite my flammable imagination (a bunch of wet newspaper(;
> > >Thanks. > > You're welcome, > Michiel
Re: Energy levels of 1D infinite square well with perturbation. Date: 1996/02/05
In article <4f0e7f$gct@hearst.cac.psu.edu> ale2@psu.edu (ale2) writes:
> Consider the two lowest energy wavefunctions of a particle in a > one-dimensional infinite square well of length L. They are proportional > to: > > F1 = sin(Pi*x/L) > F2 = sin(2*Pi*x/L) > > The above functions if squared will be symmetric about the point x=L/2. > > Now consider the change in the wavefunctions if there is a small > constant force in say the positive x direction. If I understand the > problem the new wavefunctions squared will no longer be symmetric about > the point x=L/2. The small constant force causes the particle to be > more likely to be found in the first (last) half of the square well if > the unperturbed wave function is anti-symmetric (symmetric). > > If I try to use a little classical reasoning (not right) one might > think that the constant force would tend to shift the "center" of > probability in the same direction for both the symmetric and > anti-symmetric states. > > Question, can someone give me a handwaving argument as to why the > "center" of probability shifts one way for symmetric states and another > way for anti-symmetric states? > > Thanks for any help, ale2@psu.edu
I got the following private reply which I pass along.
Begin quote:
I don't know if anyone tried to answer your question. I also don't know the level of your background. Here goes.
It's simply a matter that the postulates of quantum mechanics require wave functions of different levels to be orthogonal. (That is, the integral, over the 1D well, of the product of two wave functions must give zero.) If one level peaks to the left of center, you should be able to convince yourself with some sketches that the next level has to be distorted to the other side if the area underneath the product of the two is to be zero. If one level is "even", the next is "odd".
End quote.
From that big black GR book, Matter tells space how to .... Date: 1996/02/07
From page 5 of that big black GR book,
"Space acts on matter, telling it how to move. In turn, matter reacts back on space, telling it how to curve."
I would like to think that this is somewhat how one can think of say electrons. Matter is to an electron as spacetime is to something. An electron is some dynamical thing that reacts with or on something, this something in turn reacts back on any other electron in the neighborhood including the source. When we have a bunch of Bose particles in the ground state don't they all have the same phase, is this them reacting on something in some minimal way?
This is a half cooked idea, needs to simmer for a couple more months.
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