Letters from and to the editor of IJMPD
2009, November 22
Dear Professor Antoci,
I am not a general relativist. However, I found reading of your "The group
aspect in the physical interpretation of general relativity theory"
(Co-authored Dierck-Ekkehard Liebscher) thought provoking. I would like to
see your ideas expanded and made accessible to every PhD-level student of
physics. Would you, possibly with your collaborator(s), consider writing
such a paper for the December 2010 Special Issue of Int. J. Mod. Phys. D
Ideally, such a paper should be self contained. Or, any of the
assertion/results that are invoked must be readily accessible in a
publication at essentially the same level as your own paper. If this turns
out to be difficult, you may consider presenting an extended addendum in a
separate paper in a later issue of IJMPD.
If you agree and accept my invitation I would need from you a list of
suggested referees, and a thorough discussion of the concerns raised by
Malcolm A.H. MacCallum in Gen. Rel. Grav.38:1887-1899,2006.
You may have up to 50 pages of IJMPD. Your paper, if accepted for
publication, shall be printed under 'Invited Reviews and Papers'. The
deadline for the final draft to arrive my offices is 30 July 2010.
I hope you find this invitation of interest. I await your disposition.
Special Papers Editor, IJMPD
Senior Lecturer (Editor, IJMPD, MPLA, IJMPA)
Department of Physics and Astronomy
University of Canterbury, Private Bag 4800
Christchurch 8020, New Zealand
2009, November 25
Dear Dr. Dharam Vir Ahluwalia,
please, forgive me for not answering earlier to your very kind invitation.
My delay was not due to some hesitation, but to a short holiday in my
beloved Venice. As soon as I found your mail, I contacted Professor
Ekkehard Liebscher, who lives in Potsdam, and whose collaboration
in the studies of general relativity
was crucial in stating our early findings,
ten years ago, and in understanding later that
those early findings were not
just occasional remarks on a particular solution to the field
equations of general relativity. Our present understanding
has rather emerged as a
general viewpoint in the interpretation of that theory,
based on two early, seminal
works by Erich Kretschmann (1917) and by Emmy Noether (1918).
The manuscript now present in the Cornell Archive, entitled
``The group aspect in the physical interpretation of general relativity
theory'', that drew your attention at ``thought provoking'', was written by us
only under the invitation by an editor, Frank Columbus. As such,
that manuscript is now promised for publication as a chapter in a
book by Nova Publishers, hopefully in the first quarter of 2010.
Both Professor Liebscher and the present writer, however, are completely
aware that their work is not over,
and that further study of the papers by Kretschmann, Klein and Noether
in the years 1915-1918 is necessary to further develop the present
understanding. Therefore, we shall work further till the beginning of July 2010, in
order to comply both with the requirements needed to meet
the readership that you have in mind in your invitation,
and to obtain the accomplishment of our own theoretical goals.
In particular, I shall devote my efforts to such goals, meant as the
ones of a present-day theoretical
physicist that still draws his inspiration from the ideas that where
deeply debated during the
development of general relativity, and have inadvertently settled like
mere habits of mind in later times.
By the beginning of July 2010, a list of referees will be provided too.
It is not our intention, however, to enter
a personal discussion with Professor Malcolm A.H. MacCallum
about the concerns raised by him in Gen. Rel. Grav *38*, 1887-1899 (2006).
We refrain, like we did in the past, from
any sort of ad personam rebuttal. Otherwise, we risk to enter a sort of
eristic dialectic (see Schopenhauer's ``der Kunst, Recht zu behalten'')
on particular issues, while forgetting
to strengthen and to enlighten the general character of the group
of general relativity that we have adopted, from which the
interpretation of particular solutions
with a nontrivial Killing structure immediately stems in particular cases.
It is our opinion that, once the general viewpoint
by Kretschmann and by Noether
is understood and accepted by the reader, its consequences will be
accepted too like corollaries,
no matter how momentous and debatable
they may look to a reader not yet aware of
the above mentioned, general viewpoint.
We therefore aim at providing you with a deepened account of our former
group-theoretical inquiry by the beginning of July, as promised.
Many thanks again for your invitation.
All the best.
2009, November 26
Dear Professor Antoci,
Personally, I think scholarship has suffered under uncritical acceptance of
many of our theoretical foundations. This is even more true for relativity;
or, so at least it appears to me.
So, your work with Professor Liebscher carries a refreshing feeling and for
that reason your acceptance of my invitation is greatly appreciated.
I have also found that Schopenhauer's book that you mention has an English
translation. I hope to read it soon. Thanks for the reference, which in this
instance is highly relevant to me.
I look forward to receiving your manuscript for IJMPD, perhaps jointly with
With my best wishes,
2010, April 28
Dear Professor Ahluwalia,
please find enclosed the Latex file and the figures for
the paper entitled "Interpreting solutions with nontrivial Killing groups in
general relativity" by Dierck-Ekkehard Liebscher and by me.
The paper has been written by availing of the AMS style file,
but a version complying with the requirements of IJMPD
will be available if and when the paper will be accepted for publication.
We have tried to closely follow your suggestion, according to which
you would like to see our ideas expanded and made accessible to every
PhD-level student of physics. On the other side, it is our conviction
adhering to the ideas of Klein, Kretschmann and Noether a general
of both the special and the general theory or relativity emerges, that
expressed by the invariance properties of the metric against Lie
In our viewpoint, particular results, however interesting in themselves,
develop like corollaries from the adherence to the general interpretation.
By combining your pedagogic suggestion with our viewpoint, we limited
of particular examples, that was multifarious and review-article-like in
paper to just one simple, pedagogic example. We discuss here what
the choice of the vacuum manifold originally done by Karl Schwarzschild
in 1916 is
examined with due attention to its peculiar Killing group structure, and
pathologies and singular behaviours come out when the above mentioned
structure is overlooked in the choice of the manifold.
You have asked me to provide a list of referees. Please find
the four following names and e-mail addresses:
I am most grateful for your very kind invitation and stay,
2010, November 5
Dear Professors Antoci and Liebscher,
Below I attach a referee report for your kind consideration. Please revise
your manuscript following referee's suggestions and concerns and send it
back to me asap.
D. V. Ahluwalia
Special Papers Editor, IJMPD
Referee Report on "Interpreting Solutions with nontrivial Killing group in
general relativity" by S. Antoci and D-E Liebscher.
The present paper adds a good deal of
knowledge to the history of relativity theory and is worth being
published. Especially, literature which was originally in German language,
and is not always translated up to now, is cited. Unfortunately, a large
number of German words now appear in the text, and the non-German reader
might be frustrated to read "Mitschleppen" without translation, one could
at least say: it is the noun related to the verb "lug" in English, but
"luggage" would only roughly meet the German meaning of it.
Also, I would advise in this special case, that for all papers from
old journals the complete titles both in original and in english language
be given, as these papers are not easy to find in typical libraries.
However, I have a great problem with chapter 6: Already
M. MacCallum in GRG 38 (2006) 1887, see also gr-qc/0608033, wrote a paper
where he critizised Antoci and Liebscher, e.g. for using the word
"singularity" in a sense differently from its typical use in the field.
Even if this critizism may be a little bit too harsh, I think, they
should at least cite it, as it refers to the same topic as chapter 6
of the present paper. When they write (page 9, 10 lines from below):
"One cannot accept ... invariant quantity ...may diverge somewhere...",
then this is against usual interpretation. Example: 1/R, the inverse of
the scalar curvature, is obviously an invariant quantity and diverges
in empty spacetime; of course, regions of spacetime, where 1/R changes
from positive to negative values, do not have any special property.
This is just the same with the invariant parameter alpha in eq.(6.4).
So, the calculations seem correct, but the interpretation in this case
is simply wrong, even if Karl Schwarzschild in 1916 might have been
debated in this way, too.
Section 6 must either be completely deleted, or edited greatly to
completely remove the confusion.
2010, November 7
Dear Professor Ahluwalia,
thank you for your letter. We changed the article in each point
noted by the referee, i.e.
we dropped the interpretation "singularity" in section 6 with the
citation of MacCallum's paper exactly as the referee proposed,
we added the full titles of each cited paper and added for the
purely English reader translations of the titles which are not in English,
and we added an english explanation for german words in the text.
2010, November 9
Dear Professor Liebscher and Professor Antoci,
Thank you for your e-mail and for sending the revised draft. I have passed
through the manuscript through the referee, and sought additional advice. It
is the recommendation of my referees¹ that while reference to MacCallum should
be retained, Sections 6 and 7 distract from the main argument and, in fact,
hurts your main argument advanced in Sections 1-5. I agree with this
Would you, therefore, be so kind as to revise the manuscript accordingly. I
would very much like the revised draft to meet the approaching deadline to
close the December Special Issue of IJMPD. For this reason your prompt
attention would be most helpful.
D. V. Ahluwalia
Special Papers Editor, IJMPD
2010, November 16
Dear professor Ahluwalia,
thank you for your letter. We are happy to see that the referee now
has no more objective objections. His new claim that the sections 6 and 7
would distract from the main argument cannot be accepted. These sections are
-- in our view -- exemplifications of the main argument,
which happily enough exist in the
simple case of the Schwarzschild field.
We are aware of that the facts which we exhibit do not fit
the standard expectation. Of course, it is not necessary to
call these by words (like singularity) which have in General
Relativity a more specialised meaning than in everyday use.
Therefore we followed the request to drop the interpretion
by these notions. Words are hollow shells.
No referee objected the calculations, which are simple enough.
The diverging values of the acceleration in a very simple case exist,
and they are measureable in principle without any trick.
Sections 6 and 7 are corollaries to 1 by 5, and no distraction.
In his first statement the referee admitted just the same,
namely that the line of section 6 is like
the one Schwarzschild used.
Consequently, we will not change the text.
We are really sorry to be forced to put you in a worried position.
If you feel not to publish the present article
because one of the referees feels that
sections 6 and 7 distract from the main argument,
so just drop it.
With full acknowledgement of the troubles you take
1. The value of 1/R, which was cited by the referee as a quantity
similar to the acceleration in question, is of a truely different
type, because R is the measured quantity, not 1/R. If one could
get rid of diverging values just by only switching the attention
to the reciprocals as the referee proposes, that would help in
any place. However, 1/R nowhere couples to equations of motion,
while R does. Therefore it is the zeros of 1/R which matter
(i.e. which are measurable), not the zeros of R.
2. Whether one must, or has to, or should consider the horizon
to be a singularity or not depends on the personal point of view.
When one is happy about the possibility to continue analytically
across the horizons, the answer is clearly no.
We do not insist to preach our point of view,
that physical measurements (direct or indirect) should decide.
The numerical attempts to solve the evolution of binary black holes
decided already not to consider any interior.
That was, of course, the end of the story.