# Relativistic elasticity

lalbatros
Hello,

I have seen more than often discussions about accelerated rods, or spinning disks in relativity.
It is clear that the definition of a rigid body in relativity makes problem.

I wonder if there are some books or papers giving a complete theory for relativistic elasticity.
I have seen here and there elements of hydrodynamics or ideal fluids models or collapsing star models.
For something closer to a rigid body, is there anything to read?
Or is it a dream? (°)

Michel

(°) May well be a dream. If the strain is low enough it is maybe possible to find a frame where relativistic effects disappear. If the strain is high, the material would break anyway and an ideal fluid model would be appropriate!

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nakurusil
Hello,

I have seen more than often discussions about accelerated rods, or spinning disks in relativity.
It is clear that the definition of a rigid body in relativity makes problem.

I wonder if there are some books or papers giving a complete theory for relativistic elasticity.
I have seen here and there elements of hydrodynamics or ideal fluids models or collapsing star models.
For something closer to a rigid body, is there anything to read?
Or is it a dream? (°)

Michel

(°) May well be a dream. If the strain is low enough it is maybe possible to find a frame where relativistic effects disappear. If the strain is high, the material would break anyway and an ideal fluid model would be appropriate!

Michel,

Here is a good, elementary start:

http://arxiv.org/abs/physics/0307019

Staff Emeritus
Michel,

Here is a good, elementary start:

http://arxiv.org/abs/physics/0307019

This was a preprint from 2003. Can you please find where this was published and make that citation?

Zz.

nakurusil
This was a preprint from 2003. Can you please find where this was published and make that citation?

Zz.

To my best knowledge it wasn't published, I think that it is too elementary, it is just a good starting point for the OP to become familiar with the issue.

Staff Emeritus
To my best knowledge it wasn't published, I think that it is too elementary, it is just a good starting point for the OP to become familiar with the issue.

Well, I disagree. I'm reading the abstract, and it appears that something like this would be publishable in journals such as AJP or EJP, especially considering the claims that the authors made. One just does not write a 9-page manuscript for one's own enjoyment.

Since it isn't published, I would be very hesitant to accept something like this. And considering the "turmoil" that we seem to be getting in this particular forum lately, I am almost inclined to make a special rule for SR/GR forum to only include links to published papers.

Zz.

nakurusil
Well, I disagree. I'm reading the abstract, and it appears that something like this would be publishable in journals such as AJP or EJP, especially considering the claims that the authors made. One just does not write a 9-page manuscript for one's own enjoyment.

Since it isn't published, I would be very hesitant to accept something like this. And considering the "turmoil" that we seem to be getting in this particular forum lately, I am almost inclined to make a special rule for SR/GR forum to only include links to published papers.

Zz.

AJP and EJP editors have come up with a rule of rejecting any relativity papers. It is very interesting. As you say, this paper would have found a good home in the previous years. It is not suitable for any other journals , being too elementary. Either way, I think your rule is good.

lalbatros
ZapperZ,

SR/GR forum to only include links to published papers

• I am an hobbyist
• my yearly budget for this hobby is a few books, a few paid papers and affiliation to AAPT
• the authors do not publish for their enjoyment but to get cited
• the path to Arxiv is the best citation possible: it brings us to the title, the names and affiliations and last but not least the full text
• I really don't care to know where I could pay for the same thing
• I will only exceptionally pay for a paper
• I see no point of paying 30$for an irrelevant "published paper", as I did quite sometimes in the past, I even paid for a totally wrong paper on disk capacitors last year ! • I will stop paying for "published" papers • the most important thing is that people here try to have a scientific discussion • the added value of official science publishers is infinitesimally small: the reviewers are from the scientific community and provide the real added value and are paid generally by public institutions, publishers just print or publish on the net (everybody can do that nearly for free) • most research in fundamental science has been paid by public money, why should the papers be paid by those who paid the taxes? Just to boost some careers? • I like wiki very much, but sometimes I need more I am very sorry to drift away from my original question, but this subject is really touchy for me: I really dislike unproductive businesses specially if they are obstacles for science. Michel Last edited: Staff Emeritus Science Advisor I believe that the issue is one of peer review. While peer review does not guarantee a correct paper, it helps considerably. There are a lot of good papers on arxiv, including many that have been or will be published in peer reviewed journals. There are also some that have significant problems and aren't really publishable. As far as gaining access to papers, if you can find a local university library, you can typically get articles for$.10 or maybe $.15 per page. If you are lucky, the university will let you download papers into a flash drive - I'm not sure how common this is but I know of one university that does this. This will totally eliminate cash costs (though there will still be some cost for ink, toner, and paper). Another option is getting papers at your local non-university library through interlibrary loan - also about$.10 per page for our library (but with a $2.00 minimum). Of course this can be inconvenient, esp. if one is busy with other things. I really don't know what to make of the paper being mentioned here - using google scholar, I can't find any mention of an English language publication. Staff Emeritus Science Advisor Education Advisor AJP and EJP editors have come up with a rule of rejecting any relativity papers. How do you know this? What if I can point out SR/GR papers in these journals? Zz. Staff Emeritus Science Advisor Education Advisor ZapperZ, Please consider a few things: • I am an hobbyist • my yearly budget for this hobby is a few books, a few paid papers and affiliation to AAPT • the authors do not publish for their enjoyment but to get cited • the path to Arxiv is the best citation possible: it brings us to the title, the names and affiliations and last but not least the full text • I really don't care to know where I could pay for the same thing • I will only exceptionally pay for a paper • I see no point of paying 30$ for an irrelevant "published paper", as I did quite sometimes in the past, I even paid for a totally wrong paper on disk capacitors last year !
• I will stop paying for "published" papers
• the most important thing is that people here try to have a scientific discussion
• the added value of official science publishers is infinitesimally small: the reviewers are from the scientific community and provide the real added value and are paid generally by public institutions, publishers just print or publish on the net (everybody can do that nearly for free)
• most research in fundamental science has been paid by public money, why should the papers be paid by those who paid the taxes? Just to boost some careers?
• I like wiki very much, but sometimes I need more

I am very sorry to drift away from my original question, but this subject is really touchy for me: I really dislike unproductive businesses specially if they are obstacles for science.

Michel

But you also have to consider the VALIDITY of your source! That should be your utmost concern, not getting "free, cheap information".

We already have had MANY discussion about peer-reviewed journals. In fact, as it is now, there is not a whole of excuses for not citing them because many of then can be had for free. IoP makes available ALL of their papers free for the first 30 days that paper appears online. APS are also beginning to make some papers available for free for those in which the authors pay for free access. Furthermore, many libraries and schools pay for site-wide access, so all you need is a computer terminal at these locations and you get all of the important journals.

So consider this as an advanced notice. If one cites a paper that isn't peer-reviewed, be forwarned that such a thing may not be allowed in here. There will be exceptions to this, such as talks or lecture notes done by prominent physicists. However, we will evaluate this on a case-by-case basis.

Zz.

lalbatros
ZapperZ,

I can only agree with that:
But you also have to consider the VALIDITY of your source!
But till now I did not find anything better!
I thought that Sedov would have a chapter on that, and I found nothing except the usual stuff of relativity. I thought Landau, ... same result. Nothing in MTW, nothing in Weinberg, nothing on "living reviews", ... nothing on wiki ...

I am not very sure about the paper suggested by nakurusil, but at first reading it gives me a useful direction, it does not look bad.

Now with this remark:
If one cites a paper that isn't peer-reviewed, be forwarned that such a thing may not be allowed in here.
I could accept the rule.
But this rule would be totally counter productive.
A discussion on a forum is not a peer-reviewed publication.
If some people writes down his idea, it would be ok on the forum. And this is not peer-reviewed anyway.
If the same guy finds exactly the same idea in a not reviewed paper, it would not be ok.
Why could we not consider an "non official" paper as an idea like any idea from people here?
But I understand that such a freedom also opens a door for some abuses.
Honestly, if you applied this rule strickly, I would preffer reading Weinberg and stop discussing here.

I had little activity on this forum since months. But in the past I did quite some work for a discussion here on fringe fields in capacitors. I even developped program and had exchanges outside the forum on this. You know what: the only reference that I used and that was totally wrong was a paid and peer-reviewed reference. For the rest, I simply used what I learned at school and could develop a boundary-element method in MATLAB to illustrate my points. But this was not peer-reviewed.

In a forum like here, one should also learn some freedom of thought.

Michel

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Staff Emeritus
But this rule would be totally counter productive.
A discussion on a forum is not a peer-reviewed publication.

A discussion isn't. But citing works to validate your discussion is. You seem to be confusing the two.

Would you rather someone cite a crackpot website to support his/her argument? Have you seen forums at allow such a thing? How "productive" do you think they are?

If you are basing your argument on something, then it should be based on established physics OR something that has been peer-reviewed. If not, it is against the Guidelines that you have agreed to. It is that simple.

Zz.

lalbatros
ZapperZ,

I don't agree:

... But citing works to validate your discussion is ...

A citation is not always intended to validate a point of view.
It can be intended to help people. This was the intention of nakurusil.

Crackpots, for me, are people who want to support their view in any way.
Crackpots can be right or wrong, but they don't follow logic and rule, they rely on force and weight.

I know very well crackpots. Just have a look at one of my discussions there:

http://forum.physorg.com/index.php?showtopic=7599&st=495 [Broken]

Therefore, I understand that you care to avoid such discussions here.
I have explained in physorg that they should moderate their site, and they don't want it unfortunately.
You can see from my answer that I try to bring some rationlity in these discussions, without hope.
You will also see that "official publication" (like those by CM Will) can be used by crackpost and turned upside down to support their view.

The point is not about using peer-reviewed papers. The point is about behaviour and honesty. Only moderate moderation can help.

I thank again nakurusil for the refrence, and I would be very much interrested by your review of this paper.

It is that simple.
For me it is not that simple.

Michel

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lalbatros
Just to share my luck, here is a refereed paper that should satisfy my wishes:

http://arxiv.org/PS_cache/gr-qc/pdf/0211/0211054.pdf" [Broken]

Michel

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Staff Emeritus
Here's my $.02. The paper being cited seems a bit shrill, and it is disturbing that I can't find any reference to it being published. On the other hand, when I gave it a 2 minute glance, there were not any glaring errors. But I haven't looked at it deeply, and I probably won't have the time. Note that it is generally not necessary to go to a library to find out if an arxiv paper has been published - google scholar will usually do a good job of finding the source if you give it the title. So you can distinguish between papers that have been published and papers that haven't. As far as evaluating the quality of a paper, I agree that it is not a simple task. Eliminating non-peer reviewed papers can avoid a lot of nonsense, but it will both eliminate some good papers, and let some bad ones through. But I will say that one should be much more on guard when one reads a paper that has not been published in a peer reviewed journal. The onus lies on the reader to evaluate the source. If the reader has enough expertise, he can evaluate the arguments for himself or herself. If the reader doesn't know much about the field, he has to rely on indirect methods like closely evaluating the source rather than directly evaluating the arguments. Staff Emeritus Science Advisor Education Advisor A citation is not always intended to validate a point of view. It can be intended to help people. This was the intention of nakurusil. But this is EVEN worse. Citing something that could be wrong in the hope to TEACH someone or clarify something is the worst thing you can do. I would say that under such circumstances, it is even MORE imperative that one use a verified source! Zz. Science Advisor Homework Helper Gold Member Maybe the rule should be that each URL is accompanied by an honest declaration by the poster indicating - the author and professional affiliation of the URL (e.g. Prof. N.E. One, Some University) - whether or not it is published in a peer-review journal, and if not... what is it? article for submission? lecture notes? slides from a talk? essay? video seminar? merely a website? - relation with the poster, if any (i.e., "poster is the author", poster is a collaborator, poster knows the author) - a statement by the poster on his/her familiarity with all or part of the work (i.e. "I've only looked at part II in detail") - disclosure of known disagreements with the mainstream - in other words, "why should we trust this resource?" (and you, the poster?) while it should always be up to the reader to beware and judge the references, maybe things like this might help (if done with honesty). my$0.02

Just to share my luck, here is a refereed paper that should satisfy my wishes:

http://arxiv.org/PS_cache/gr-qc/pdf/0211/0211054.pdf" [Broken]

If I'd read this thread earlier, that's exactly what I would have posted. It's quite good. Carter and Quintana's paper (the 2nd reference in the link) is also very useful.

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lalbatros
ZapperZ,

But this is EVEN worse. Citing something that could be wrong in the hope to TEACH someone or clarify something is the worst thing you can do.

It COULD be that in real life we may have to think and develop critical sense.
Real life, and nature have not been peer-reviewed.
Silence is no way to teach either.
Honest efforts in a discussion should be highly respected.

Michel

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Staff Emeritus
ZapperZ,

It COULD be that in real life we may have to think and develop critical sense.
Real life, and nature have not been peer-reviewed.
Silence is no way to teach either.
Honest efforts in a discussion should be highly respected.

Michel

.. and who gets to decide who is honest and who isn't?

Look, we have TRIED all this before, and we were innundated with all kinds of crackpottery. That is why we had to draw a clear line in the type of sources that can be used.

In the end, this is a judgment call, and all I'm saying is that if one uses unpublished work as a reference, be prepared to see it possibly being deleted.

Zz.

lalbatros
ZapperZ,

I just wanted you not throw the baby with the water of the bath.

The reference provided by nakurusil can be criticised without any doubt.
Nevertheless I found it mind opening.
The simple (but not rigourous) approach in this paper, a sort of energy balance, is worth reading.
Maybe even worth improving. And it could be compared with a more rigourous analysis too.
One should not forget that the Lagragian or action principle approach in theoretical physics has been refined from such simpler arguments. It is never bad to go back to the basics (my motto).

Honestly, over-simplification is sometimes a much better way to understanding than over-complication so common in "serious" peer-reviewed papers. No doubt that the sectarian language complexity is for something in today's low interrest for science. Complexity can be used to justify a salary sometimes ...

Michel

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