ueb wrote:

If I understand the moderator properly, this would mean, one
introduces additional terms to curl A in order to get the
(non-existing !) magnetic monopoles.
As old-fashioned I am, I'd think that a theory, which forbids
non-existing things, be a proper theory, and a theory, which
predicts non-existing things, should be given up.

If a theory predicts that such and such an entity does not exist, all
that it means is that the existence of such and such an entity is
inconsistent with the postulates of the theory. In that case the
nonexistence is a property of the theory, and not the world.

No theory can positively say that in reality an entity cannot exist,
unless that entity was paradoxically defined. The only thing we can be
sure is right is the principle forbidding inconsistency.

Bob Kolker

ueb wrote:
What do you actually want to say ? What would you prefer if nature
is not as nice to show us a certain entity -
a theory, whose postulates are inconsistent with the entity, or
a theory, whose postulates are consistent with even that entity ?
(In which the first is consistent with a lot of entities which
nature kindly shows us.)

I mean to say, that if a theory predicts the non-existence of an entity,
this does not preclude the possibility that the theory is wrong and that
the entity in question may yet be discovered (by means outside the
theory).

On the other hand if a theory predicts the existence of an entity we
should be happy if we discovered that entity. But keep in mind that
absence of evidence is not necessarily evidence of absence.

Here is a specific example. If our theories tell us that a magnetic
monopole does not exist that is a restriction arising from the theory
itself. The theory cannot live with magnetic monopoles. If, perchance, a
magnetic monopole if every discovered, it is time to discard that theory.

What really exists or does not exist is a property of nature not of our
theories. Nature is what it is and if nature could care (which she cant)
she does not give a damn what our theories are or even if we theorize.
Nature is not bound by man made rules. Man made rules should be bound by
nature.

Bob Kolker

Robert J. Kolker wrote:


ueb wrote:

If I understand the moderator properly, this would mean, one
introduces additional terms to curl A in order to get the
(non-existing !) magnetic monopoles.
As old-fashioned I am, I'd think that a theory, which forbids
non-existing things, be a proper theory, and a theory, which
predicts non-existing things, should be given up.

If a theory predicts that such and such an entity does not exist, all
that it means is that the existence of such and such an entity is
inconsistent with the postulates of the theory. In that case the
nonexistence is a property of the theory, and not the world.

I must be a lot more old-fashioned than I thought up to now !
I took existence respectively non-existence always as a proporty
of the world. This hopelessly obsolete method made me see known
particle numbers in tensor equations from GR + EM.

No theory can positively say that in reality an entity cannot exist,
unless that entity was paradoxically defined. The only thing we can be
sure is right is the principle forbidding inconsistency.

Bob Kolker

What do you actually want to say ? What would you prefer if nature
is not as nice to show us a certain entity -
a theory, whose postulates are inconsistent with the entity, or
a theory, whose postulates are consistent with even that entity ?
(In which the first is consistent with a lot of entities which
nature kindly shows us.)

Ulrich Bruchholz

Robert J. Kolker wrote:


ueb wrote:
What do you actually want to say ? What would you prefer if nature
is not as nice to show us a certain entity -
a theory, whose postulates are inconsistent with the entity, or
a theory, whose postulates are consistent with even that entity ?
(In which the first is consistent with a lot of entities which
nature kindly shows us.)

I mean to say, that if a theory predicts the non-existence of an entity,
this does not preclude the possibility that the theory is wrong and that
the entity in question may yet be discovered (by means outside the
theory).

On the other hand if a theory predicts the existence of an entity we
should be happy if we discovered that entity. But keep in mind that
absence of evidence is not necessarily evidence of absence.

Here is a specific example. If our theories tell us that a magnetic
monopole does not exist that is a restriction arising from the theory
itself. The theory cannot live with magnetic monopoles. If, perchance, a
magnetic monopole if every discovered, it is time to discard that theory.

What really exists or does not exist is a property of nature not of our
theories. Nature is what it is and if nature could care (which she cant)
she does not give a damn what our theories are or even if we theorize.
Nature is not bound by man made rules. Man made rules should be bound by
nature.

Bob Kolker

Ok. (In which I remember an opposite statement, but that may be my
minor skills of the English language.)
In order to keep your words:
The critical point is apparently the *false* claim that the postulates
of GR (and continuum theories at all) be inconsistent with the
quantum phenomena. Einstein knew it better.
I wonder what is so hard to understand here ? Each child knows that
the integration constants of wave (and related) equations take on
discrete values. And the quantities of particles are the first
integration constants of the (source-free) Einstein-Maxwell
equations ! (The magnetic monopole is not under them.
People must say goodbye to the matter sources like _distributed_
masses and charges. These and _only these_ are inconsistent with
the quantum phenomena, and cause lots of difficulties also in
GR itself ! Paying attention to this very elementary, GR and
electrodynamics are unified to a general geometric theory of
fields, without any inconsistency up to now.
The point of my criticism is, that people, instead of taking notice
of the facts (i.e. results of numerical simulations according to
above mentioned equations), insist on the false claim (which
Einstein has not shared), and ignore all that could refute the
false claim. Not enough, they defame the originator of evidence
as crank, and prevent other from taking notice of facts or
evidence.

Ulrich Bruchholz