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What do quantum theorists see when they look at a brick? Date: 1999/02/01
What do you quantum field theorists see when you look at a solid piece of matter such as a brick or the plastic case of your computer?
Let me suggest why I am interested. The "machinery" of quantum mechanics and quantum field theory is one of the pinnacles of human thought and to it and to those who understand it I bow in respect .
As I understand it any experiment we might choose to preform theory will give us the probabilities of all possible outcomes. Now when I stare at a piece of matter I get this feeling that matter does its stuff (or some of its stuff) in 3 space dimensions and one time dimension (even if there are other dimensions a la string theory). It seems there must be an interpretation of quantum mechanics and quantum field theory that allows us a picture of "stuff" in 3 space dimensions that says given this "picture" that it is only natural that matter be described using the mathematics of quantum field theory.
Two sources gave me inspiration for such a picture. Penrose's work with past and future light cones and the following paper:
"The Transactional Interpretation of quantum mechanics" by John G. Cramer in Reviews of Modern Physics, Vol. 58, No.3, July 1986, pages 647-687. Quoting from the abstract:
"The interpretational problems of quantum mechanics are considered. The way in which the standard Copenhagen interpretation of quantum mechanics deals with these problems is reviewed. A new interpretation of the formalism of quantum mechanics, the Transactional Interpretation, is presented. The basic element of this interpretation is the transaction describing a quantum event as an exchange of advanced and retarded waves, as implied by the work of Wheeler and Feynman, Dirac, and others. The transactional interpretation is explicitly nonlocal and thereby consistent with recent tests of the Bell inequality, yet is relativistically invariant and fully causal..."
John Cramer also has a web page which covers the Transactional Interpretation of Quantum Mechanics. This should get you there:
Link to Cramer's Transactional Interpretation. In particular consider this graphic (click here).
I would like to think that the emitter and absorber in the above graphic do not really send waves in both directions in time but that each particle of matter is in some sense "connected" with every other particle of matter and that the advanced and retarded waves of Cramer's work can be reinterpreted as each particle constantly absorbing and emitting "stuff". The stuff that a particle absorbs comes from the stuff each of the other10^80 particles emits and the stuff that a particle emits will, because of the "connections", eventually be reabsorbed by some of the other 10^80 particles.
So picture each particle in the universe is connected pair-wise to every other particle in the universe. Picture disturbances of these connections as bose particles. If true in some sense, we are all connected to each other! I move and in doing so a disturbance spreads outward to each and everyone of you. Wait, I sense Feynman just rolled over in his grave, %^)
If the picture has any hope of being right spinors must some how pop out of it, is that possible? %^[
phi-wt+d = 0 in another frame? Date: 1999/01/21
The function phi-wt+d = 0 is my tinker-toy spin. Phi is the cylindrical coordinate, w is omega the angular frequency, t is time, and d is a real constant. I would like to determine how this function transforms into another relativistic frame. If you see any major errors in what follows please point them out.
I was interested in how a spinning bicycle wheel would appear (bad word choice, I should used "be measured") to someone rushing past it. Consider those points phi, rho, and t such that phi-wt+d = 0 with d taking on the values;
and constrain the radial coordinate rho so that 0 < rho < R
Such points form a "bicycle wheel" of 30 spokes that rotates with angular frequency w. Consider how the points that make up one such spoke transform for someone rushing past these points with speed v in the +y direction. We have;
but phi = arctan(y/x) so arctan(y/x) - wt+d=0
now let t --> g(t'+vy'/c^2), y --> g(y'+vt'), x --> x' and we have;
Clearly not the implicit function of a straight line?
I rush past your gyroscope, what do I measure? Date: 1999/02/01
Let S_1 be the vector which represents the spin angular momentum of your spinning gyroscope. I rush past your gyro at .9 c and I measure the spin angular momentum of your gyro and I call it S_1'. You give the gyro a new arbitrary orientation but keep the magnitude of the spin angular momentum the same, S_i/|S_i| = constant.. Again I rush past your gyro at .9 c and measure the spin angular momentum of your gyro and call it S_2'. This process is repeated N times, where N is a large number. Assume I always rush past you from the same direction.
After this is done you get out Mathematica and make two 3D plots of the two sets of spin vectors, the set you measure and the set I measure. The plot of your set of spin vectors will be pointing in roughly all directions but the plot of my set of spin vectors will tend to point in two opposite directions?
How does classical spin transform relativistically? Date: 1999/02/03
If a spinning gyroscope went past real fast I must measure the same magnitude for the spin angular momentum as a person in the rest frame of the gyro, yes?
But I would measure and say that the gyro's spin was more aligned with the direction in which it went past then the person in the gyro's rest frame, yes?
If the gyro went by at .99999c I would measure the spin to be aligned (or antialigned) with it direction of motion, yes?
This seems like it should be a simple calculation?
Scalar fields in fractal dimensions? Date: 1999/02/03
Can anyone think of any interesting effects that might occur with scalar fields in fractal dimensions?
Could one have a scalar field such that at each small region of the field the dimensionality of the field was a variable?
Can a system go from say effectively 3 dimensions smoothly to one of effectively 2 dimensions and then smoothly to one of 1 dimension?
I was thinking of a point disturbance in S^N and how if N is odd the point disturbance must start out as a wave with no afterglow but that eventually interesting "things" might happen as S^N is not flat?
Thanks for pointing me in the right direction!
Velocity, density, ect. : air : molecules :: spinor field :?:? Date: 1999/02/08
Consider a compressible fluid such as air. Assume we can neglect viscosity. We might quantify such a fluid at some small region with a set of numbers. Three numbers would give the components of the velocity vector of the air at that small region and two more numbers would give the density and temperature of the air in that same small region.
Now suppose we have continuous functions of position and time that give the velocity, density, and temperature of air in some large region of interest. If we evaluate these functions at a "point" we must be clear that these functions only make sense if the "point" is in fact a region that is macroscopically small but large in the sense that the region contains many molecules.
So we have continuous vector and scalar fields that describe the state of air which on a large scale can be thought of as a continuous compressible substance when in fact air is made up of numerous particles.
In a similar manner can one envision a multitude of discrete "things" (points, lines, or surfaces ect with extra properties as needed to solve the problem) such that a very small region (say 10^-60 m^3) would contain many of these "things" so that for all practical purposes one would have a continuous field made up of discrete things that sit in spacetime that would be properly described by a spinor field?
Can anyone think of something that might work?
Link to thread of next article. Re: Hottest Part of Candle Flame. Date: 1999/02/11
From: mbobrowsky@stsci.edu << Many sources state (without referencing an authoritative source) that the blue part of a candle flame is the hottest part. Does anyone know of a reliable reference for that? You can't compare it to stars, where the blue ones are the hottest, because the candle flame is not a blackbody. I'd like to find a good description of the different parts of the flame, giving the chemical reaction, temperature, etc. Suggestions? >>
You got some good replies. Damn I like usenet!
I got out a candle and some thin (.18mm) copper wire, lit the candle, and probed around the flame with the wire. The candle flame was about 1.5X.25 inches in size. The wire would get hot enough so that it glowed orange in the hotter parts of the flame and would easily melt while in the hottest parts. Granted my method is not that scientific it still is instructive.
Conclusion, the hottest part of the flame seems to be half way up and right outside the yellow part of the flame, in the part of the flame where no visible light is given off!
Re: Hottest Part of Candle Flame. Date: 1999/02/17
From: "Bill J, Edinburgh" <maestro@cix.co.uk>
<< Again, I advocate an experiment before hypothesizing. Don't say you can't afford a diffraction grating. Use a CD covered with paper with a radial slit in it. >> Me too, so ...
Get the cord from an old appliance or any electrical wire that is not solid wire but is made of many smaller wires (.18mm diameter works good for a candle flame of 1.5x.25 inches). Strip insulation from end of cord thus exposing the copper wires. Take one wire and wrap around a pin in the form of a helix (the helix shape gives a longer conduction path, reduces error). Light candle and probe flame with helix and note the places (only the hottest) where the wire melts.
Theory is all fine an dandy but is sometimes wrong, though results of experiments can also be interpreted wrong.
Of course, I highly doubt that UFOs exist in reality. Date: 1999/02/18
From: Jonathan A Goff <jongoff@et.byu.edu> << ... Of course, I highly doubt that UFOs exist in reality. ... >> How far away would you say the nearest intelligent life form is, in light years (excluding our solar system) ?
Do you exclude the possibility that life forms far more intelligent than humans exist (far more as in ant:human::human:superior alien life forms).
Do you exclude the possibility that technology far in advance than our own might exist?
Just curious what educated people think about "distant" life.
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