I agree with Margaret about how we should behave as responsible
scientists. However, I want to speak up in defence of all my
colleagues who have patiently spent a lot of time with Koenemann at
conferences in the past twenty years or so, listening to his
arguments, giving advice. Some were not convinced, others were; his
work is published in peer-reviewed journals and on the internet. This
is how science should be done.
For myself, I am still waiting for the definition of a physical
experiment which is unambigious, and a prediction of Koenemann about
the outcome of this experiment, with which he can show that his theory
is superior to existing ones. In his work I have not found such a
description.
A very similar challenge was posed to him in a discussion on this
topic in the mechanics community at http://imechanica.org/node/5321
Janos Urai
On 25 Mar 2011, at 22:43, Dr. Margaret C. Brewer-LaPorta wrote:
I don’t agree. While I am extremely dismayed with Falk’s comment on
“black Jewish homosexual child-raping ex-convict”…I am taking it in
the context in which it was delivered, one of extreme frustration with
a community of people who call themselves scientists. If indeed Falk
is accurate with his description of the treatment that he has received
at scientific meetings; where he has been told to keep quiet, or told
that his attendance was not welcome, or he has been yelled down from
the mike…then there is a disturbing problem within our community that
demands not only our attention, but immediate correction. His
negative comment is a direct expression of how he feels he has been
treated at the hands of people who are supposed to be his peers.
While his comment does nothing to engender respect for the position he
finds himself in, it does not make his position any less of a grave
concern.
As scientists we have an obligation greater than just the discussion
of hypotheses, theories and the experimentation that validates or
invalidates them…we have an obligation to protect the free expression
of ideas within our ranks, including ideas we do not agree with.
This e-mail thread is a forum for open communication, is it not? I
have been dismayed at the calls to shut down this thread because some
feel this is not the place for active discussion of unpopular,
misunderstood or unwelcome ideas. I am also extremely disturbed at
the thought that some may not want to know about the troubles Falk has
faced. It is exactly these kinds of encounters that we must hear
about. Denying the existence of the devil, only gives him more power
over you. I would much rather hear about such troubles in an open
forum of communication, instead of hearing about them the way most
folk usually do…as whispers in a crowded room combined with the
shaking of heads and tssking of tongues, as if the whispered events
are an uncontrollable evil. I have read plenty about the feelings of
those who don’t want to hear about Falk’s dilemma; however, I haven’t
seen one piece of advice for him on how he could positively deal with
the situation he is in. We must proactively combat such
unprofessional and unscientific treatment of our peers; otherwise we
are equally as culpable as the perpetrators themselves.
Respectfully,
Margaret Brewer-LaPorta, Ph.D.
Tectonic Stratigrapher/Senior Research Scientist
LaPorta and Associates, L.L.C.
Geological Consultants
<image001.jpg>
From: Tectonics & structural geology discussion list [mailto:[log in to unmask]
] On Behalf Of Douwe van Hinsbergen
Sent: Friday, March 25, 2011 5:08 PM
To: [log in to unmask]
Subject: Re: Combined replies
I agree.
On Fri, Mar 25, 2011 at 5:05 PM, Healy, David <[log in to unmask]>
wrote:
This is the limit for me:
The concatenation of 'black Jewish homosexual child-raping ex-convict'
is UTTERLEY offensive.
This thread must stop here. This is not the science I signed up for.
Cheers,
Dave
On 25 Mar 2011, at 19:06, "Falk H. Koenemann" <[log in to unmask]>
wrote:
Combined replies
First of all, I am very satisfied with this discussion. This is more
discussion than I have found in 20 years.
I reply to those emails which have to do with the theory. If I take my
time to reply – well, you want thoughtful answers, right?
Michele Cooke:
The spherical element example presented by Koenemann is the case of
pure shear with non-zero distortional work. While Koenemann contends
that the tensional work offsets the compressional work on the sphere,
the strains also need to be considered. The compressional stress
(negative) produces a contraction strain (negative). Mechanical work
is 0.5 * stress * strain so that in this zero volume loss example, the
tensile work and compressional work are equal and both positive
leading to a non zero physical work.
If contractional work is negative, extensional work must be positive.
If you do it under isotropic boundary conditions – a gas or a solid –
you shift in PV space to the left or right, so there must be two signs
for the work.
Your comment shows another flaw in the theory: the improper cause-
effect relation. In thermodynamics you have the material properties
(the EOS), the cause (Delta P), and the work equation then gives you
the effect – Delta V, and its sign comes from the cause, not from an
extra theory. In principle it should work the same way in anisotropic
loading, but that's not the case. Look into Malvern: there is one
chapter on stress, then you turn the page and find everything about
strain, but how you get from A to B is not at all clear. In effect –
this is Cauchy's legacy – you have two independent theories side-by-
side, which are then somehow glued together. Say, you know the sign of
stress in a particular direction – compressive – so you also know the
sign of the effect – shortening – and then you multiply them and
always end up positive. That can't be right.
The theories of stress and strain cannot relate to one another: Stress
is not a concept in Euclidean space whereas strain is. I think that a
proper theory of deformation does not need a strain theory.
Thermodynamics doesn't. My theory doesn't, but it gives you the
distortion nonetheless. – Besides, the strain concept has its own
weakness, strain is not a state function (cf. page 7).
To say that physical work hasn't found much attention in continuum
mechanics is overly provocative in my opinion.
I stand by my remark. I have read books on fracture mechanics. I am
not saying that these authors are sloppy, I just say that there are
too many non-sequiturs in the theory, your trouble with the sign of
work is a telling example. A phenomenological theory may work well in
practice even if it is theoretically ill-founded. The flat-earth
theory works perfectly at the scale of your office – even at much
larger scale, say your campus, but that still doesn't make it right.
-----------------------------------------
Ernie Rutter
‘Real’ solid and viscous materials have bonds but continuum
mechanics does not need to consider them.
Just so? That's not enough. Bonds are forces which interact with the
external forces. If bonds are not considered the equilibrium equation
is incomplete. It's that simple. Deformation work is work done upon
bond lengths. If you leave out bonds, what do you do work upon? In
thermodynamics the case is clear: if there are bonds, the internal
pressure (dU/dV)_T is quite high, that's the term the surrounding
interacts with. In a gas it is zero.
Of course, crystalline materials are anisotropic on account of how
bonds are arranged, but continuum mechanics does not need to be
concerned with that at all. Imagine a solid with a Poisson ratio of
0.5. It must deform elastically at constant volume. If it is loaded
axisymmetrically but with the orthogonal principal stresses zero, the
greatest principal stress will do work but in the radial direction the
expansion takes place against zero load, so no work is done. The
result is that the solid deforms at constant volume but overall
mechanical work is done (which you get back when the load is removed).
A more general material with Poisson ratio less than 0.5 undergoes
volume change but a non-isotropic deformation still does mechanical
work on it.
Not so. The material contracts if the boundary conditions permit it.
In this example you imply those of a wire in freespace, and then the
Poisson ratio may work, but it is phenomenological. If the same wire
is encased in some rigid material it cannot attenuate, no matter what
Poisson's ratio says.
My point here is that Poisson's ratio is a fudge factor that is
numerically not wrong under the boundary condition for which it was
meant – a wire in freespace. But if I see questions in the literature
what Poisson's ratio might be for the material in the lower mantle –
boy, the nearest free surface is 3000km away! Rather, a purely
phenomenological theory was developed for wires in freespace, at a
time when it was far too early to properly assess the physical problem
as such, and then it was transposed a little thoughtless to the
conditions of an infinitely extended continuum, and suddenly you have
terms in your theory which make sense only at the surface.
The cause of attenuation is not a material property called Poisson's
ratio, but the law of least work: if you stretch the wire and prevent
the attenuation, the work done is far higher because you get a volume
change. Therefore as you do work on the wire in X, the wire does work
upon the surrounding in Y and Z. You can even measure this saved work:
stretch the wire in X and let it attenuate, and then pull the lateral
surfaces out again until there is no change of length in Y and Z. I
think that a proper theory of deformation should predict the effect
described by Poisson's ratio, we do not need this fudge factor. – I
found that there are three independent sets of boundary conditions:
(1) the material properties, (2) the force configuration that acts
upon the thermodynamic system, (3) the spatial extent of the bonded
continuum that contains the system, i.e. the shape of the sample. If
the old theory started by considering wires in freespace, I think we
must go precisely the opposite way: consider a system in an infinite
bonded continuum, and then find out what happens if you reach a free
surface.
Falk’s assertion that ‘the stress tensor does not exist’ is unhelpful
and misleading. It is a concept that continues to serve us well in the
everyday world.
"Proof of existence" in mathematics means proof that a concept,
postulate or theorem is compatible with common logic. I have shown
that Cauchy's tensor is not in line with common logic. You say you
happen to like the concept. But that's not a mathematical or physical
argument. – Excuse me, Ernie, we have had this very point in a direct
conversation before. Whether an idea comes handy or looks good enough
for government work is not a criterium, or else we would still believe
in ether or phlogiston. I am doing my best to get us out of this
phenomenological mess. You seem to think "If I can measure it, it is
there". I think that you don't know what you are measuring. It is the
concepts that guide you, and all I am saying is that we need new
concepts. My claim that the Cauchy stress is incompatible with
standard physical logic (that it "does not exist") is unchallenged.
The truth is – and this applies to the great majority of my colleagues
– that you (plural) have probably never really heard about potential
theory because it is not taught in continuum mechanics classes. The
reason is simple: continuum mechanics is historically older, and
stands massively in contrast to it, it has ignored it. But potential
theory is right. If you are entirely insensitive to its rules, that
does not make the rules irrelevant, but it means that there is
something new to learn. I sincerely hope that I am not understood as
being arrogant now, I am deadly serious, and urging.
If Falk wants to argue that there is something wrong with continuum
mechanics, he must point it out with examples that make sense and
provide the experimental proof of his assertions, or indicate where
existing theory fails and leads to blatantly wrong results.
Simple shear provides a plethora of examples, not just in mylonites. I
make the claim that I have found the reason for turbulence in viscous
flow, S-C-fabric, joint orientation etc. It is my peer's job to look
at the results. – Since 1997 I have been to ca. 25 conferences. I
never get the mike, always a poster, and nobody comes to see it.
Asking others to come see my poster was the best way to make sure they
would not come. Exception: I had the mike at the TSG meeting in
Manchester 13 years ago which Ernie chaired; but then a jaded queen
remarked that what I do is not structural geology, and that was the
entire discussion. If there is no poster session it has already
happened that I was told by phone that my presence at the conference
is unwanted (in Germany). When I tried to say something in Liverpool
TSG 2009 when the discussion was opened for general topics, I was
yelled down by the session chairman (you know who). All this amounts
to a suffocating excommunication. The noise right now is the result.
Altogether, I have been shunned by my peers like a black Jewish
homosexual child-raping ex-convict who is out on parole, the contempt
is physically sensible. Notable exceptions are few, in particular
Ernie Rutter and Brian Evans who have always treated me with genuine
decency and not a trace of condescension. This is the right place to
express my thoroughly heartfelt gratitude, you don't know what an
exception you are.
I have plenty of testable predictions, what I need is an audience
willing to pay attention. I am grateful for the discussion here. And
whoever pays the ticket – I have a nice Powerpoint talk to offer.
Judge my work after you have seen it.
-----------------------------------
Kurt Stüwe
Theories are never RIGHT or WRONG. Theories are only CONSISTENT or
INCONSISTENT with observations and theories are only USEFUL or NOT
USEFUL. In order to be useful, a theory must explain observations in
nature in a simplified way so that the student of the problem feels he/
she understands something he/she has observed.
Sorry, theories can be terribly wrong if their mathematical-physical
structure is not in accordance with standard physics. Mixing up
Newtonian mechanics and thermodynamics is such a non-accordance. What
you say here is a free ticket to unlimited phenomenology, which is a
sure way into never-never-land.
Your father was a kind man. But statements such as the above are an
attempt to avoid theoretical discussion altogether.
------------------------------------
Mark Fisher
Thank you to Rob Twiss for reminding everyone that this debate with
Falk Koenemann has already taken place.
Rob Twiss hasn't said anything yet. He only said he is not going to
say anything, and that he once said something 10 years ago, which was
also just that he is not going to say anything. In fact he is not even
talking to me, only to everyone else. The truth is, Rob Twiss is in
trouble. There is something you cannot know: I was his student. I got
the basics from him in 1980-82. When I tentatively formulated my first
independent thoughts years later he instantly took refuge into
silence. Now, 22 years later, he finds to his dismay that the thing he
tried to quench is still at his door step. In the meantime he has
written two textbooks and grown into the senior authority in
theoretical matters in structural geology and feels that everyone is
waiting for him to say something – not me, I have given up on him, but
the rest of you. Let's see what happens.
Falk
.__________________________________________________________
| Dr. Falk H. Koenemann Aachen, Germany
| Email: [log in to unmask] Phone: *49-241-75885
| www.elastic-plastic.de
The University of Aberdeen is a charity registered in Scotland, No
SC013683.
--
http://www.geologist.nl
Douwe J.J. van Hinsbergen, PhD
Center for Advanced Study
Norwegian Academy of Science and Letters
Drammensveien 78
NO-0271 Oslo
Norway
Tel: +47 22122514
[log in to unmask]
and
Physics of Geological Processes (PGP)
University of Oslo
Sem Sælands vei 24
NO-0316 Oslo
Norway
Tel: +47 22856487
currently visiting at
Geophysical Laboratory
Carnegie Institution for Science
5251 Broad Branch Rd. NW
Washington DC 20015, USA
<Dr Margaret Brewer-LaPorta.vcf>
|
