Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
Jefimenko on Causality and Physical Laws
88 views
Skip to first unread message
Engr. Ravi
Mar 8, 2021, 5:54:41 AM3/8/21
to
"""
ONE OF THE MOST IMPORTANT TASKS OF PHYSICS is to establish causal relations between physical phenomena. No physical theory is complete unless it provides a clear statement and description of causal links involved in the phenomena encompassed by that theory. In establishing and describing causal relations it is important not to confuse equations which we call “basic laws" with “causal equations.” A “basic law" is an equation (or a system of equations) from which we can derive most (hopefully all) possible correlations between the various quantities involved in a particular group of phenomena subject to the "basic law." A “causal equation,” on the other hand, is an equation that unambiguously relates a quantity representing an effect to one or more quantities representing the cause of this effect. Clearly, a “basic law" need not constitute a causal relation, and an equation depicting a causal relation may not necessarily be among the “basic laws" in the above sense.
Causal relations between phenomena are governed by the principle of causality. According to this principle, all present phenomena are exclusively determined by past events. Therefore equations depicting causal relations between physical phenomena must, in general, be equations where a present-time quantity (the effect) relates to one or more quantities (causes) that existed at some previous time. An exception to this rule are equations constituting causal relations by definition; for example, if force is defined as the cause of acceleration, then the equation F = ma, where F is the force and a is the acceleration, is a causal equation by definition.
In general, then, according to the principle of causality, an equation between two or more quantities simultaneous in time but separated in space cannot represent a causal relation between these quantities. In fact, even an equation between quantities simultaneous in time and not separated in space cannot represent a causal relation between these quantities because, according to this principle, the cause must precede its effect. Therefore the only kind of equations representing causal relations between physical quantities, other than equations representing cause and effect by definition, must be equations involving "retarded" (previous time) quantities.
"""
And we have Doubtin' Tom saying that causality is of no concern to "real" physicists!
ONE OF THE MOST IMPORTANT TASKS OF PHYSICS is to establish causal relations between physical phenomena. No physical theory is complete unless it provides a clear statement and description of causal links involved in the phenomena encompassed by that theory. In establishing and describing causal relations it is important not to confuse equations which we call “basic laws" with “causal equations.” A “basic law" is an equation (or a system of equations) from which we can derive most (hopefully all) possible correlations between the various quantities involved in a particular group of phenomena subject to the "basic law." A “causal equation,” on the other hand, is an equation that unambiguously relates a quantity representing an effect to one or more quantities representing the cause of this effect. Clearly, a “basic law" need not constitute a causal relation, and an equation depicting a causal relation may not necessarily be among the “basic laws" in the above sense.
Causal relations between phenomena are governed by the principle of causality. According to this principle, all present phenomena are exclusively determined by past events. Therefore equations depicting causal relations between physical phenomena must, in general, be equations where a present-time quantity (the effect) relates to one or more quantities (causes) that existed at some previous time. An exception to this rule are equations constituting causal relations by definition; for example, if force is defined as the cause of acceleration, then the equation F = ma, where F is the force and a is the acceleration, is a causal equation by definition.
In general, then, according to the principle of causality, an equation between two or more quantities simultaneous in time but separated in space cannot represent a causal relation between these quantities. In fact, even an equation between quantities simultaneous in time and not separated in space cannot represent a causal relation between these quantities because, according to this principle, the cause must precede its effect. Therefore the only kind of equations representing causal relations between physical quantities, other than equations representing cause and effect by definition, must be equations involving "retarded" (previous time) quantities.
"""
And we have Doubtin' Tom saying that causality is of no concern to "real" physicists!
Helmut Wabnig
Mar 8, 2021, 7:32:27 AM3/8/21
to
what then?
w.
Maciej Wozniak
Mar 8, 2021, 7:49:19 AM3/8/21
to
physicist in general; he writes what (according to him) should
be instead what is.
> There is a cause and no effect,
> what then?
You're too stupid to notice it's a quoting. Right?
Still, poor halfbrain, I can answer instead both of them.
https://dictionary.cambridge.org/dictionary/english/cause
if it has no effect it's not any cause.
Tom Roberts
Mar 8, 2021, 12:35:08 PM3/8/21
to
On 3/8/21 4:54 AM, Engr. Ravi wrote:
> """ ONE OF THE MOST IMPORTANT TASKS OF PHYSICS is to establish causal
> relations between physical phenomena.
That is the archaic hope of physicists of the mid-19th century and
> """ ONE OF THE MOST IMPORTANT TASKS OF PHYSICS is to establish causal
> relations between physical phenomena.
earlier. Such hopes have been completely dashed by discoveries in the
late-19th century and later -- many physical phenomena simply do not
operate causally.
Example: emission of light from an incandescent light bulb. At the macro
level, sure: the electric current can be said to "cause" the emission of
light [#]. But at the atomic level, there is no such "causality" at all
-- the emission of photons is an inherently stochastic process.
[#] But there is an infinite chain of such "causes",
and it is not possible to choose any particular one
as "THE cause". In this case that extends back to the
electric generator, to the mining of materials used
to construct the generator and the light bulb, to the
production of elements in supernovae billions of
years ago, to....
Writers like Ravi, apparently Jefimenko, and many others around
here, are fooled by apparent causal behavior at human scales, completely
ignoring the non-causal behavior of quantum phenomena at atomic scales
(and below).
Remember that all things at human scales are comprised
of atoms.
> No physical theory is complete unless it provides a clear statement
> and description of causal links involved in the phenomena encompassed
> by that theory.
To demonstrate that to yourself, you should attempt to describe such a
"complete" Newtonian mechanics. Be sure to use "THE cause", and avoid
any sort of infinite regress.
> [...] A “causal equation,” on the other hand, is an equation that
> unambiguously relates a quantity representing an effect to one or
> more quantities representing the cause of this effect.
How could that possibly work???? -- an equation is a statement of
> more quantities representing the cause of this effect.
mathematical equality between two quantities. In physics, that generally
expresses a 100% correlation.
Repeat the mantra: correlation is not causation.
QUESTION: on a pool table the cue ball is moving and the 8 ball is at
rest; the cue ball hits the 8 ball and subsequently both balls move in
different directions. What "causal equation" applies?
ATAICT there is no such thing as a "causal equation". Please demonstrate
one. Be sure to use "THE cause", and avoid any sort of infinite regress.
> Causal relations between phenomena are governed by the principle of
> causality. According to this principle, all present phenomena are
> exclusively determined by past events.
electrodynamics, and General Relativity, the equations of motion can be
solved when given sufficient boundary (initial) conditions. While not
the "causal equation" fantasized above, that does describe the
subsequent behavior of the system.
That simply does not apply to quantum mechanics or QFT. For them, the
most that is possible is a statistical description of possible
subsequent behaviors. Quantum phenomena are NOT "exclusively determined
by past events" -- THEY ARE STOCHASTIC.
> [... further elaboration of such nonsense]
You, and presumably Jefimenko, need to learn modern physics -- you're a
century or more out of date. You're just using empty, undefined phrases
like "causality" and "causal equation" to fool yourselves.
Tom Roberts
Werner Macadams - DPhil
Mar 8, 2021, 6:24:51 PM3/8/21
to
Tom Roberts wrote:
> On 3/8/21 4:54 AM, Engr. Ravi wrote:
>> """ ONE OF THE MOST IMPORTANT TASKS OF PHYSICS is to establish causal
>> relations between physical phenomena.
>
> On 3/8/21 4:54 AM, Engr. Ravi wrote:
>> """ ONE OF THE MOST IMPORTANT TASKS OF PHYSICS is to establish causal
>> relations between physical phenomena.
>
> Example: emission of light from an incandescent light bulb. At the macro
> level, sure: the electric current can be said to "cause" the emission of
> light [#]. But at the atomic level, there is no such "causality" at all
> -- the emission of photons is an inherently stochastic process.
> [#] But there is an infinite chain of such "causes", and it is not
> possible to choose any particular one as "THE cause". In this case that
> extends back to the electric generator, to the mining of materials used
> to construct the generator and the light bulb, to the production of
> elements in supernovae billions of years ago, to....
yOU confuse *cause_effect* directional relationship with inherited
> level, sure: the electric current can be said to "cause" the emission of
> light [#]. But at the atomic level, there is no such "causality" at all
> -- the emission of photons is an inherently stochastic process.
> [#] But there is an infinite chain of such "causes", and it is not
> possible to choose any particular one as "THE cause". In this case that
> extends back to the electric generator, to the mining of materials used
> to construct the generator and the light bulb, to the production of
> elements in supernovae billions of years ago, to....
*causation*. Different things.
Werner Macadams - DPhil
Mar 8, 2021, 6:26:27 PM3/8/21
to
Engr. Ravi
Mar 10, 2021, 6:01:21 AM3/10/21
to
On Monday, March 8, 2021 at 11:05:08 PM UTC+5:30, tjrob137 wrote:
> On 3/8/21 4:54 AM, Engr. Ravi wrote:
> > No physical theory is complete unless it provides a clear statement
> > and description of causal links involved in the phenomena encompassed
> > by that theory.
> Hmmm. No physical theory to date has ever done such a thing.
>
> On 3/8/21 4:54 AM, Engr. Ravi wrote:
> > No physical theory is complete unless it provides a clear statement
> > and description of causal links involved in the phenomena encompassed
> > by that theory.
> Hmmm. No physical theory to date has ever done such a thing.
>
> > [...] A “causal equation,” on the other hand, is an equation that
> > unambiguously relates a quantity representing an effect to one or
> > more quantities representing the cause of this effect.
> How could that possibly work????
>
> AFAICT there is no such thing as a "causal equation". Please demonstrate
> > unambiguously relates a quantity representing an effect to one or
> > more quantities representing the cause of this effect.
> How could that possibly work????
>
> one. Be sure to use "THE cause", and avoid any sort of infinite regress.
The quote in the OP is from Jefimenko's book: "Causality, Electromagnetic Induction and Gravitation".
One of the main themes of the book is to recast Maxwell's equations in a form that meets the causality criterion, viz., the Jefimenko equations:
https://en.wikipedia.org/wiki/Jefimenko's_equations
So, there you have a demonstration of a causal law.
> an equation is a statement of mathematical equality between two quantities. In physics, that generally expresses a 100% correlation.
> Repeat the mantra: correlation is not causation.
The notion that "a changing E CAUSES a changing B and vice-versa" is at the root of the justification of the ABSURD idea that c can be constant for ALL inertial frames.
Unlike Doubtin' Tom, who thinks Jefimenko's contribution is "further nonsense", both Griffith and Jackson acknowledge that Jefimenko's equations are a useful contribution to electrodynamics.
Tom Roberts
Mar 12, 2021, 6:25:47 PM3/12/21
to
On 3/10/21 5:01 AM, Engr. Ravi wrote:
> On Monday, March 8, 2021 at 11:05:08 PM UTC+5:30, tjrob137 wrote:
>> AFAICT there is no such thing as a "causal equation". Please
>> demonstrate one. Be sure to use "THE cause", and avoid any sort of
>> infinite regress.
>
> The quote in the OP is from Jefimenko's book: "Causality,
> Electromagnetic Induction and Gravitation".
> One of the main themes of the book is to recast Maxwell's equations
> in a form that meets the causality criterion, viz., the Jefimenko
> equations: https://en.wikipedia.org/wiki/Jefimenko's_equations
Those equations, too, merely show 100% correlation, not any sort of
> On Monday, March 8, 2021 at 11:05:08 PM UTC+5:30, tjrob137 wrote:
>> AFAICT there is no such thing as a "causal equation". Please
>> demonstrate one. Be sure to use "THE cause", and avoid any sort of
>> infinite regress.
>
> The quote in the OP is from Jefimenko's book: "Causality,
> Electromagnetic Induction and Gravitation".
> One of the main themes of the book is to recast Maxwell's equations
> in a form that meets the causality criterion, viz., the Jefimenko
> equations: https://en.wikipedia.org/wiki/Jefimenko's_equations
"causation". Indeed the mathematical "=" is completely unable to show
"causation", one needs an entirely new notation [#].
[#] That same character has been co-opted in many
computer programming languages to mean assignment.
In a rather loose sense that is closer to "causation"
than the mathematical meaning of equality.
Moreover, those equations completely ignore what "causes" the point
charge(s) to follow the given trajectory. That NECESSARILY includes the
selfsame E and B fields the equations purport to show are "caused" by
the moving charge(s). Those equations are USELESS by themselves, because
charged particles are affected by the E and B fields of those equations
-- you need a complete, self-consistent approach. That is quite
difficult, and goes far beyond those equations; the challenge is to find
an approximation technique that will fit within your computing resources
(I have done so for a limited set of particle beams).
In GR, classical electrodynamics, and Newtonian mechanics, given
sufficient boundary and initial conditions one can calculate the
evolution of the system for all subsequent times [%]. That is as close
as anyone has ever come to defining "causation", but is really
determinism, not "causation".
[%] Note these are all CLASSICAL theories. No
quantum theory can do anything like this at all.
> So, there you have a demonstration of a causal law.
what that would entail.
I can see how Jefimenko fooled himself: as pointed out in the Wikipedia
article, in these equations the LHS is evaluated at time t, while the
RHS is evaluated at the 'retarded' time t-|r-r'|/c; earlier values are
regarded as "causing" the later values. But he completely forgot that
this is the Green's function for Maxwell's equations, which are
invariant under time reversal -- these equations are equally valid for
the 'advanced' time t+|r-r'|/s, in which case one would say that the E
and B fields "caused" the charges.
> [... further nonsense omitted]
Bottom line: All the above is irrelevant for fundamental theories of
physics, because it is ignoring the quantum nature of the world we
inhabit, which makes it completely and utterly useless.
Tom Roberts
Brodie Wiser
Mar 12, 2021, 8:54:04 PM3/12/21
to
Tom Roberts wrote:
>> Electromagnetic Induction and Gravitation".
>> One of the main themes of the book is to recast Maxwell's equations in
>> a form that meets the causality criterion, viz., the Jefimenko
>> equations: https://en.wikipedia.org/wiki/Jefimenko's_equations
>
> Those equations, too, merely show 100% correlation, not any sort of
> "causation". Indeed the mathematical "=" is completely unable to show
> "causation", one needs an entirely new notation [#].
that's way in physics one uses <expectations>.
>> Electromagnetic Induction and Gravitation".
>> One of the main themes of the book is to recast Maxwell's equations in
>> a form that meets the causality criterion, viz., the Jefimenko
>> equations: https://en.wikipedia.org/wiki/Jefimenko's_equations
>
> Those equations, too, merely show 100% correlation, not any sort of
> "causation". Indeed the mathematical "=" is completely unable to show
> "causation", one needs an entirely new notation [#].
larry harson
Apr 6, 2021, 8:10:30 PM4/6/21
to
Edkah Bearden
Apr 7, 2021, 9:57:52 AM4/7/21
to
larry harson wrote:
> You can express the evolution of the fields entirely in terms of the
> retarded positions and velocities of the source charges; but not in
> terms of the advanced positions and velocities generally, where the
> radiation field has to be added in to maintain time reversibility. You
> can't reverse radiation by reversing the trajectories of the charges.
>
>> > [... further nonsense omitted]
Could rapid development of China’s digital currency threaten US' global
> You can express the evolution of the fields entirely in terms of the
> retarded positions and velocities of the source charges; but not in
> terms of the advanced positions and velocities generally, where the
> radiation field has to be added in to maintain time reversibility. You
> can't reverse radiation by reversing the trajectories of the charges.
>
>> > [... further nonsense omitted]
dominance? RT’s Boom Bust digs in, lol.
This is what happens, when big tech, as TI, wont give free chips samples
to people anymore. China is already decades ahead capitalist us. That's
why you got the corona. Is this so difficult for you to undrestand?
They call me names, give me a break. It's obvious, a liar has to have a
good memory, but there are no memories regarding the fake moon landing.
0 new messages