ueb:

I don't deny that QM may tell something of non-existence in
statistical models.

Statistical models are usually attempts to give those things existence
and then ignore them as buried under the statistics.

But I mean something different. -
Take the popular example of the Four (meanwhile five ?)
fundamental "forces". How do you measure or observe at all
the "strong" and the "weak force"?

It's really very straight-forward. The strong force is easily observed
the same way that electromagnetic forces are observed. You scatter two
nuclei and plot the angular distribution. If you scatter protons off
of protons, you have two contributions to the scattering, the coulomb
interaction and the nuclear force. One already knows how to compute the
coulomb interaction, so you can subtract the contribution due to coulomb
scattering from the angular distribution. This turns out to be pretty
much irrelevant at all but extremely low energy where the two protons
never get very close to each other (like a couple MeV). One can check
this strategy by doing n-p scattering and n-n scattering where there
is no coulomb potential and see if the numbers are the same. As it
turns out, the coulomb force is so insignificant that n-n scattering
and p-p scattering differ less than than that caused by the spin
dependence in n-p scattering. After all, the only two nucleon system
that forms a bound state is n-p. n-n is unbound.

The weak interaction is harder to study because the force is
very short range, but the standard way to study it via nuclear
beta decay. One can first produce an unstable nucleus and then
look at the decay times, gamma rays, endpoint energies and
branching ratios to different daughter states and compare that
with calculated values. You get agreement as good as parts in 10^6
or better if the nucleus is not too complex.

In any case, the existence of those interactions is not an artifact
of quantum mechanics. If you didn't have quantum mechanics as the
mechanics used to explain it, you'd still have to use something.

Bilge wrote:
ueb:
Bernardz:
Oh its [QM] certainly useful and works in many situations.

Bilge:
Name a situation in which it doesn't work.

I'm afraid that you deliberately overtax him. -
I recall a guy named Popper who told that a theory must be falsifiable.
According to that, quantum mechanics is no theory at all. Because it
has been designed according to special observations, and uses lots
of unseen quantities. It may be a makeshift, which is legitimate
for the real success in the semiconductor industry.
In order to understand the world, GR might be on the right track.
Even the direct unification of GR with EM lets see particle numbers.

On the contrary, what quantum mechanics says about things which are
unobservable, is that they don't exist. I have no idea how you arrived
at the opposite conclusion, given the fact that a commutator like
[p,x] = -i\hbar explicitly tells you that exact values of p and x
don't exist simultaneously.

I don't deny that QM may tell something of non-existence in
statistical models. But I mean something different. -
Take the popular example of the Four (meanwhile five ?)
fundamental "forces". How do you measure or observe at all
the "strong" and the "weak force"? I defend myself against the
imagination that any strange "force" is needed to hold together the
protons in a nucleus. I'd rather think that the model is false.
However, numerical simulations according to the Einstein-Maxwell
equations reveal nuclei (under them the single proton, and the free
electron too) as discrete solutions of these tensor equations.
One does not need such imaginations then.
Don't wrongly understand me: It is not my goal to run quantum
mechanics down. It may be a really useful tool. But it may not
obstruct the view to alternatives (which could be better for
the future).

Ulrich

Bilge wrote:
ueb:
...
But I mean something different. -
Take the popular example of the Four (meanwhile five ?)
fundamental "forces". How do you measure or observe at all
the "strong" and the "weak force"?

It's really very straight-forward. The strong force is easily observed
the same way that electromagnetic forces are observed. You scatter two
nuclei and plot the angular distribution. If you scatter protons off
of protons, you have two contributions to the scattering, the coulomb
interaction and the nuclear force. One already knows how to compute the
coulomb interaction, so you can subtract the contribution due to coulomb
scattering from the angular distribution. This turns out to be pretty
much irrelevant at all but extremely low energy where the two protons
never get very close to each other (like a couple MeV). One can check
this strategy by doing n-p scattering and n-n scattering where there
is no coulomb potential and see if the numbers are the same. As it
turns out, the coulomb force is so insignificant that n-n scattering
and p-p scattering differ less than than that caused by the spin
dependence in n-p scattering. After all, the only two nucleon system
that forms a bound state is n-p. n-n is unbound.

The weak interaction is harder to study because the force is
very short range, but the standard way to study it via nuclear
beta decay. One can first produce an unstable nucleus and then
look at the decay times, gamma rays, endpoint energies and
branching ratios to different daughter states and compare that
with calculated values. You get agreement as good as parts in 10^6
or better if the nucleus is not too complex.

Thanks for the careful explanation.

In any case, the existence of those interactions is not an artifact
of quantum mechanics. If you didn't have quantum mechanics as the
mechanics used to explain it, you'd still have to use something.

So ? ;-)
May I nevertheless remark that the interpretation of these scattering
experiments is tied to even these special models ? I find it very bold
to claim the existence of new fundamental interactions from the
scattering behaviour of nuclei or particles. In which, also the
Coloumb force is not relevant, though this macroscopically exists,
unlike strong or weak interactions.
I would accept such interactions, if not were the fully geometric
model that does simply not need them, and exclusively deals with
*directly* observable quantities (which do not take certain special
models for granted). For that reason, I indeed take those interactions
as an artifact of quantum mechanics.

Ulrich

ueb:
Bilge wrote:

In any case, the existence of those interactions is not an artifact
of quantum mechanics. If you didn't have quantum mechanics as the
mechanics used to explain it, you'd still have to use something.

So ? ;-)
May I nevertheless remark that the interpretation of these scattering
experiments is tied to even these special models ?

You may remark that, but there is nothing special about scattering
that depends upon those models. Scattering starts with a simple
assumption that the outgoing flux is related to the ingoing flux
through some function called a scattering cross-section. In particular,
for an ingoing flux of particles, n particles/unit area, the number
of outgoing particles scattered into a solid angle, d\Omega, is given by,

Number scattered = (incident particles/unit area) x cross section

From that, you can either find a potential function by brute force
that gives you that cross section or make an astute guess. For example,
if you choose a 1/r potential, you get ordinary coulomb scattering.
You can't reproduce nuclear scattering with a 1/r potential. Generally,
nuclear forces are complex enough that the potentials are determined
phenomenologically, so that any model dependence is rather generic.
One basically treats the nucleus like one would treat light scattering
from a sphere. Then, one can build in things which are rather familiar
from E&M, like skin depth, opacity, etc., so that you have a
potential with real and imaginary parts in terms of some parameters,

U = V f(r,r_v, a_v) + iW f(r, r_s, a_s)

where r is the radius, r_v is a constant determined by fitting which
is related to nuclear volume, r_s is is a constant that corresponds
to the thickness of the nuclear surface (i.e., analogous to skin
depth) and a_v and and a_s are called the volume and surface diffuseness.
The imaginary term iW allows for absorption. So basically, this
model makes few assumptions that couldn't be applied to anything.

The general form of f(r, r_i, a_i) that provides the best fits
are typically some variety of woods-saxon shape like,

f(r, r_i, a_i) = 1/[1 + \exp((r - r_i)/a_i)]

[There are occasionally additional terms included to account for
spin-orbit forces, which migh incluyde both real and imaginary
parts to account for scattering which could transfer angular
momentum]

One then writes a computer program to take scattering data and
obtain a best fit for the parameters.

If the scattering were consistent with electrical forces, the
potential one obtained would give constants V and W that were
consistent with the strength of the electric charge. But it
doesn't. Also, the parameters that one gets indicates the
nuclear force saturates. That is, the force is finite range and
becomes constant at a short distance inside the nuclear surface.

None of this is really model dependent, since the model itself
comes from fitting parameters. One then _deduces_ the properties
from the fitted parameters.

Quantum mechanics main purpose here is that it enables one to
treat the particle flux in terms of a wave equation and green's
functions. Usually, one can refine the fitting technique somewhat
using a procedure called the Distorted Wave Born Approximation,
(DWBA), but that really has no impact on the general result that
nuclear forces are not electromagnetic.

I find it very bold
to claim the existence of new fundamental interactions from the
scattering behaviour of nuclei or particles. In which, also the
Coloumb force is not relevant, though this macroscopically exists,
unlike strong or weak interactions.

There is a reason for that. If you have a potential with a finite range,
it has no effect once you get very far away. The finite range is a
direct consequence of the mass of the particles mediating the force.
In the case of the strong interaction, the mass of the pion was
deduced by knowing the range of the force. The range of the force was
determined from scattering data using even simpler techniques than
given above. Basically, all that was done was to find the scattering
length for low energy scattering, which is somewhat like looking
at the diffraction of light from a disk.

I would accept such interactions, if not were the fully geometric
model that does simply not need them, and exclusively deals with
*directly* observable quantities (which do not take certain special
models for granted). For that reason, I indeed take those interactions
as an artifact of quantum mechanics.

It's no more an ``artifact'' than determining crystal structure
by electron crystallography.

To Bilge:
First, thanks for the explanations re scattering.
At a first glance, that you told could very well support even the
geometric model. Because the potential components follow the 1/r
potential only in the far field, and reach abruptly a geometrical
limit at a radius of nearly 10^{-15}m. This geometrical limit
happens at the 10^{40}fold amount of the far field at this radius
(in metrics, in which electromagnetism goes quadratically into
metrics).
I'll still more careful read your answer, but that needs time.
You can also reach me under info at bruchholz minus acoustics dot de .

Ulrich

Bilge wrote:
ueb:
Bilge wrote:

In any case, the existence of those interactions is not an artifact
of quantum mechanics. If you didn't have quantum mechanics as the
mechanics used to explain it, you'd still have to use something.

So ? ;-)
May I nevertheless remark that the interpretation of these scattering
experiments is tied to even these special models ?

You may remark that, but there is nothing special about scattering
that depends upon those models.

I think too, and your following explanations demonstrate it.
For that reason, I spoke of interpretation, and meant the interpretation
that concludes special interactions. But there is an interpretation
without building block models that does not need special interactions.

Scattering starts with a simple
assumption that the outgoing flux is related to the ingoing flux
through some function called a scattering cross-section. In particular,
for an ingoing flux of particles, n particles/unit area, the number
of outgoing particles scattered into a solid angle, d\Omega, is given by,

Number scattered = (incident particles/unit area) x cross section

From that, you can either find a potential function by brute force
that gives you that cross section or make an astute guess. For example,
if you choose a 1/r potential, you get ordinary coulomb scattering.
You can't reproduce nuclear scattering with a 1/r potential.

Even. My simulations demonstrate that very impressively. The potential
quantities take on 10^{20}fold amounts and go into metrics with
10^{40}fold amounts of the linear values at an radius of nearly
10^{-15}m .

Generally,
nuclear forces are complex enough that the potentials are determined
phenomenologically, so that any model dependence is rather generic.
One basically treats the nucleus like one would treat light scattering
from a sphere. Then, one can build in things which are rather familiar
from E&M, like skin depth, opacity, etc., so that you have a
potential with real and imaginary parts in terms of some parameters,

U = V f(r,r_v, a_v) + iW f(r, r_s, a_s)

where r is the radius, r_v is a constant determined by fitting which
is related to nuclear volume, r_s is is a constant that corresponds
to the thickness of the nuclear surface (i.e., analogous to skin
depth) and a_v and and a_s are called the volume and surface diffuseness.
The imaginary term iW allows for absorption. So basically, this
model makes few assumptions that couldn't be applied to anything.

The general form of f(r, r_i, a_i) that provides the best fits
are typically some variety of woods-saxon shape like,

f(r, r_i, a_i) = 1/[1 + \exp((r - r_i)/a_i)]

[There are occasionally additional terms included to account for
spin-orbit forces, which migh incluyde both real and imaginary
parts to account for scattering which could transfer angular
momentum]

You have slipped from reality to an image. :-)
I know such image well from electrical engineering. But engineers
always distinguish between reality and image. Do physicists do that
too ? (Are you aware that nature does not know complex quantities ?)
- Remember your sentence ``One basically treats the nucleus like
one would treat light scattering from a sphere.'' That is a *very*
special model, and I find it really bold to take it for granted.

One then writes a computer program to take scattering data and
obtain a best fit for the parameters.

If the scattering were consistent with electrical forces, the
potential one obtained would give constants V and W that were
consistent with the strength of the electric charge. But it
doesn't.

Even. But the scattering seems very consistent with the results
from my simulations. Particles, nuclei, even atoms are discrete
solutions of the Einstein-Maxwell equations there. With the got
proportions, they cannot behave like a charged sphere, but the
scattering seems to support even the got proportions. Such
discrete solutions do _not_ consist of any building blocks.
For that reason, I'm very distrustful about the existence of
quarks.

Also, the parameters that one gets indicates the
nuclear force saturates. That is, the force is finite range and
becomes constant at a short distance inside the nuclear surface.

Do you not see that the concluded behaviour of the "nuclear force"
is extremely tied to the quite special model named by you ?
How is the state of the "nuclear surface"? (I know it - it is
a geometrical limit. Within it is nothing, not even time.)
Each imagination, what may be "inside", is irrelevant.)

None of this is really model dependent, since the model itself
comes from fitting parameters. One then _deduces_ the properties
from the fitted parameters.

Yes, indeed. Though do you not take already a model as you told, and
refine it with the fitted parameters ? No matter as it may really be,
is such method not pretty dubious ?

Quantum mechanics main purpose here is that it enables one to
treat the particle flux in terms of a wave equation and green's
functions.

The purpose sanctifies the means. What do you need above terms for ?
The wave equation and Green's functions are linear, and that does not
hold in the subatomic range.

Usually, one can refine the fitting technique somewhat
using a procedure called the Distorted Wave Born Approximation,
(DWBA), but that really has no impact on the general result that
nuclear forces are not electromagnetic.

Surely. This remark demonstrates that the "force" term is really
tied to the building block models. This term is simply not relevant
in the geometric model.

I find it very bold
to claim the existence of new fundamental interactions from the
scattering behaviour of nuclei or particles. In which, also the
Coloumb force is not relevant, though this macroscopically exists,
unlike strong or weak interactions.

There is a reason for that. If you have a potential with a finite range,
it has no effect once you get very far away. The finite range is a
direct consequence of the mass of the particles mediating the force.
In the case of the strong interaction, the mass of the pion was
deduced by knowing the range of the force. The range of the force was
determined from scattering data using even simpler techniques than
given above. Basically, all that was done was to find the scattering
length for low energy scattering, which is somewhat like looking
at the diffraction of light from a disk.

I would accept such interactions, if not were the fully geometric
model that does simply not need them, and exclusively deals with
*directly* observable quantities (which do not take certain special
models for granted). For that reason, I indeed take those interactions
as an artifact of quantum mechanics.

It's no more an ``artifact'' than determining crystal structure
by electron crystallography.

I may summarizingly state that the scattering data indicate proportion
and course of the potential quantities, and nothing else. That looks
consistent with the discrete solutions of the Einstein-Maxwell equations,
i.e. supports the geometric model (that *without* additional dimensions).

Ulrich