Quantum Gravity

[CanadaAotS]

About the Casual Sets... in a way isnt every single particle influencing every single other particle any way?

 

I would think so at least... and if that were true what would the point of it be? I'm probably just not getting it -_-' lol

[Martin]

About the Casual Sets... in a way isnt every single particle influencing every single other particle any way?

 

I'm not all that conversant with causal sets, I can provide links to half a dozen papers but would not want to get into explaining.

 

A causet is a 4D spacetime picture.

each point or "event" has something analogous to a forward lightcone of other events that it COULD influence----same as the set of spacetime points that LIGHT FROM IT COULD REACH

 

each point or event in the causal set also has something analogous to a BACKWARDS LIGHTCONE of all the events which could have 'sent it messages' or influenced it in some way

 

and then there are a lot of events which have no direct causal connection----things happening outside your past or future lightcones so to speak

 

but the causet is DISCRETE so it is like a cloud of dust particles in 4D and there are not really "cones" like there would be in continuous geometry

 

enough said! it is a rather offbeat approach to QG.

only if someone is especially interested in just that approach would I suggest some reading

 

major causalset authors are: Faye Dowker, Joe Henson, Rafael Sorkin

you can look up their papers on arxiv if you want.

[Martin]

periodically I check research output at Harvard abstracts using keywords

superstring, M-theory, brane, heterotic, AdS/CFT

for 6 years 2001-2006

 

we only know the number of publications up thru August 2006, so for now each year has to be restricted to Jan-August to make them comparable. the trend is downwards, from 868 articles published in Jan-Aug 2001 down to 619 published Jan-Aug 2006.

Another noteable trend is "globalization"---the papers by authors in NorthAmerica&Europe constitute a smaller fraction of the total output. That is to say that the NA&E-based portion of designated research is declining more rapidly than the total.

 

2001: http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PHY&qform=PHY&aut_logic=OR&author=&ned_query=YES&sim_query=YES&start_mon=&start_year=2001&end_mon=08&end_year=2001&ttl_logic=OR&title=&txt_logic=OR&text=heterotic+M-theory+brane+superstrings+AdS%2FCFT&nr_to_return=100&start_nr=1&jou_pick=ALL&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1

 

2002: http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PHY&qform=PHY&aut_logic=OR&author=&ned_query=YES&sim_query=YES&start_mon=&start_year=2002&end_mon=08&end_year=2002&ttl_logic=OR&title=&txt_logic=OR&text=heterotic+M-theory+brane+superstrings+AdS%2FCFT&nr_to_return=100&start_nr=1&jou_pick=ALL&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1

 

2003: http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PHY&qform=PHY&aut_logic=OR&author=&ned_query=YES&sim_query=YES&start_mon=&start_year=2003&end_mon=08&end_year=2003&ttl_logic=OR&title=&txt_logic=OR&text=heterotic+M-theory+brane+superstrings+AdS%2FCFT&nr_to_return=100&start_nr=1&jou_pick=ALL&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1

 

2004: http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PHY&qform=PHY&aut_logic=OR&author=&ned_query=YES&sim_query=YES&start_mon=&start_year=2004&end_mon=08&end_year=2004&ttl_logic=OR&title=&txt_logic=OR&text=heterotic+M-theory+brane+superstrings+AdS%2FCFT&nr_to_return=100&start_nr=1&jou_pick=ALL&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1

 

2005: http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PHY&qform=PHY&aut_logic=OR&author=&ned_query=YES&sim_query=YES&start_mon=&start_year=2005&end_mon=08&end_year=2005&ttl_logic=OR&title=&txt_logic=OR&text=heterotic+M-theory+brane+superstrings+AdS%2FCFT&nr_to_return=100&start_nr=1&jou_pick=ALL&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1

 

2006: http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PHY&qform=PHY&aut_logic=OR&author=&ned_query=YES&sim_query=YES&start_mon=&start_year=2006&end_mon=08&end_year=2006&ttl_logic=OR&title=&txt_logic=OR&text=heterotic+M-theory+brane+superstrings+AdS%2FCFT&nr_to_return=100&start_nr=1&jou_pick=ALL&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1

 

One should however note that what could be regarded as the REPLACEMENT research, namely non-string QG, is growing most rapidly in NA&E institutions, mainly Canada and Europe but also at one US university (Penn State) and at one university in Mexico.

[elas]

To the extent of my limited understanding, there is nothing that describes the origins of our world as powerfully as physical cosmology

 

At last someone who believes in the reality of the interpretation of observations. But why limit yourself to cosmology surely the key is to find the link between the large scale (cosmology) and the small scale (particle physics). Both Newton and Einstein thought the final solution (TOE) would be simple. Newton realized that experiments on the small scale would not be possible in his lifetime and gave up (actually he changed jobs). Einstein derived a formula that works but cannot be explained and died still wondering why an impossible speed (C squared) plays such an important part. Since the publication of Einstein’s work we have wandered in a wilderness of despair seeking ever more improbable mathematical solutions when our time would probably have been better spent on re-interpretation – the search for a solution found by the examination of observations.

 

Why are the same fractional differences found in cosmology and particle physics? What, if any is the connection between the vortices of cosmology and the vortex created when particles collide? What is the relationship between mass and radius that appears as a fringe subject in both sciences? If electrons are the shell particles of atoms, are gravitons the shell particles of a group of atoms? Or are two similar quarks the shell particles of a single different quark?

 

I happen to believe that creation comes about by the repetition of a few simple actions on ever larger scale, and that the similarities mentioned above are the key to understanding these actions, but as long as interpretation is compartmentalized there is no hope of overlapping theories being taken seriously.

[merlin wood]

Why believe there could be a successful unified account of general relativty and the quantum theory of the standard model if, even given the quantum theory, nobody understands quantum mechanics?

 

The assumption seems to be that if you could develop a theory of quantum gravity you could then explain what is at present inexplicable in quantum theory. But is there any real justication for this assumption?

 

Why shouldn't it be the case that the behaviour that is uniquely described of quantum objects, called wave, spin and entanglement, actually has nothing to do with any of the forces, with quantum field theory only giving the illusion that this could be so?

 

Why shouldn't the quantum behaviour have its own independently acting cause, like that called the quantum potential in Bohmian mechanics, and it is for this reason that no successful theory of quantum gravity has been or can be developed?

[fredrik]

There isn't much doubt IMO that eventually there will be unification. IMO when you look at it there are major flaws in the logical foundation first of all. I think the new theory will definitely also resolve some of the present QM issues at the same time.

 

Many physicists seem to think that physics should stay away from philosophical questions and instead end up viewing physics theories as a kind of "computational procedures", that either work or doesn't work, and the question of why they work and what it means is irrelevant and left to philosophers as less important. But this attitude also seems to reject the problem of how a model come into beeing, which in my view of things is one of the key points. It's not a step we can omit.

 

Sometimes when I read papers from certain physicists I have sensed and undertone that their philosophical strategy is to try to fit observations into already existing and well understood mathematical structures blindly, and then see if it can be fiddled to comply to data. Using as major guidance some kind of beauty of mathematics. That approach never complied with my thinking.

 

I think the key is not how to support or disprove a statement or theory, the key is howto systematically resolve an inconsistency, and here deviations is your friend.

 

My personal expectations from the future unification is a proper answer to at least the following issues.

 

1) The relation and dynamics with the observers nature and the system. Sometimes the current formulation contains an assymetry that contradicts the obvious fact that an interaction is symmetric and can be described in several ways.

 

2) A more first principles view of basic concepts, mass, energy and space.

 

3) What is the key mechanism behind time evolution? What about the arrow of time in relation to the apparent lack of arrow in microphysics?

 

I see plenty of clues and I'm optimistic. I'm currently working on some ideas that will address all the above points. I think that the laws of physics will come up as stochastic patterns constrained to give constraints. So far it looks promising but there are plenty of problems that I'm trying to digest. The current issue on my mind is to unify relation between "intertial mass" and "relative confidence". There is a deeper connection that I think will give new insight into GR. The dynamics or GR can probably be seen as a simple form of dynamical evolution of inconsistencies. The conncetion between a large mass and high confidence is obvious. But I am still wondering what the proper formalism is. I've started out by a clear intuitive feeling, and now I just need to translate that into a formalism that says the same thing.

 

This is close to some other entropy methods many are working on. I wish more was working on it because I haven't found that awfully many papers as compared to string papers for example.

 

/Fredrik

[abskebabs]

From my brief knowledge of both causal sets and LQG so far; I must say I am finding both very intriguing. But regardless of this, I think that there should be at least some kind of observational or experimental results that are motivations for investigations in theoretical physics. Does either approach or any approach in quantum gravity for that matter stem from such motivations?

 

Also I have a question for Martin. Why do you prefer LQG to causal sets?(sorry if that was a little blunt)

[Martin]

...

Also I have a question for Martin. Why do you prefer LQG to causal sets?(sorry if that was a little blunt)

 

I missed this question earlier. Forgot to check the thread. If you are still interested I will try to answer.

 

Actually it has been nearly a year---3/4 of a year anyway since I wrote some dismissive comment about Causal Sets approach and i have changed my perspective some since then.

 

I have seen several 2006-2007 Causal Sets papers that seemed interesting. I'm probably less biased now.

 

You asked WHY and probably that has a lot to do with limited time and the need to focus attention.

 

The four leading non-string QG approaches---in general terms---are Loop, Spinfoam, CDT, and Causal. OF THESE ONLY ONE (Loop) HAS BEEN ACTIVELY APPLIED TO COSMOLOGY---resulting in LQC, loop quantum cosmology.

 

LQC is almost as big and active now as its parent LQG. I think if somebody did the stats they would find LQC was the fastest growing area of all.

 

Loop and Spinfoam are closely allied---same people work on both. someday they might prove that the two approaches are mathematically equivalent, only with different formalism

 

I guess part of it is my bias is towards research action. I like to read significant new results. By new I mean in the past year or so. Or even better just last month! If you have that kind of mentality, then you probably don't like String (most of the big results are from the 1990s or earlier, plus a depressing result in 2003 by Kachru, Kallosh, Linde, Trivedi, not much since). And then in the NON-STRING department there are two good reasons to focus as I do on Loop/Spinfoam

 

1. Loop/Spinfoam together is the biggest chunk of the non-string action----less research is done in CDT and Causal.

 

2. Loop/Spinfoam has Loop Cosmology as an exciting applied field.

==============

 

People could say well shouldn't I be looking for the approach that has the most chance of RIGHT? why should I be such a thrill-seeking instant-gratification sportsfan spectator? Can't you be serious, Martin?

Well the fact is that nobody knows what approach is right. You have smart highly circumspect people working in all these areas. they are alert to where their work can go wrong, and where they see gaps they constantly push to fill them.

So how am I going to second-guess? Why shouldnt I just go where there is the most action to watch?

 

If you want, let me know and I will try to list Loop Spinfoam and Quantum Cosmology developments 2006-2007. try to give you some idea

[Martin]

much of the information is old and no longer of interest.

time to unstick this thread.

[solidspin]

hello,

 

Maybe I can try to unstick this thread? Maybe it needs a new thread? Anyway, several groups (Univ. of Minn., UMass Amherst - I am happy to post the links if needed) have coincidentally and perhaps serendipitously offered some pretty interesting information regarding this topic. Further, Grandinetti, et al. just published a great paper on superadiabicity of spin ensembles.

 

I'm finishing my PhD in chemical physics and I hit upon an idea - why not TEST LQG by finding the resonance frequency of the graviton, given an easy test mass (sphere, homogeneous material like boron nitride)? Kalnins, et al. (U of Minn.) and Holstein (UMass) have separately offered very reasonable math for a 4-space version of r x p (in other words, 4-space spin angular momentum) and a gamma of 2 for the graviton, respectively. Since GR provide for torsion-free curvature, that basically eliminates the possibility of getting odd off-diagonal matrix values or additional (rank-2+n) tensors following each tangent bundle.

 

The first Hamiltonian is, obviously, the test mass itself, as that provides the first perturbation. The second Hamiltonian is placing the test mass in an appropriate B field, to remove spin degeneracy. About 1.2T and as homogeneous as possible. Third would be (depending on, as Cartan brilliantly elucidated in the 50's) adiabatically sweeping the field based on the density of the object, not the mass, but using the reconstructed spin AM tensors created by the U of Minn. group.

 

I've got the magnet, the frequency synthesizers, access to a test mass (I have boron nitride powder and a press) and I can cobble together the spectrometer from parts to which I have access. I already know how I want to write the pulse sequence I want to write, but I REALLLLLLY need help in 2 spots: 1) how do I carefully rewrite the spin |2> density matrix to reflect the linear combinations of the coherences, which are going to be manifested in the off-diagonal terms and 2) how can I cleverly incorporate the phase cycling inherent to NMR in the pulse sequence to exploit the off-diagonal terms?

 

OK, where are the flaws?

[Martin]

A person that comes to mind who knows a lot about the LQG graviton is Simone Speziale.

He has been involved in working out the LQG graviton propagator.

Unfortunately I don't have his email address.

 

Since I really don't know the ideal person to write, I can only suggest you try someone at Perimeter institute, like e.g. Sundance Bilson-Thompson. If he likes the idea (regardless of possibe flaws) he might suggest the right person to contact. Here is a list of all the PI postdocs.

http://www.perimeterinstitute.ca/index.php?option=com_content&task=view&id=30&Itemid=72&e=Postdoctoral%20Researchers&cat_id=432&cat_table=3

 

There is also Olaf Dreyer at MIT. His research is mainly in LQG but he is in touch with condensed matter physicists like X.G. Wen who is also at MIT.

odreyer-at-mit-dot-edu

There may be other people it would be better to write about this. And of course I can't guarantee that anyone will respond. Personally I am not able to evaluate your experiment concept.

Edited January 6, 2009 by Martin

[solidspin]

Martin -

 

thx for the response - I will surely take your suggestions as to contact persons...but, even theoretically, do you think there's a shot? I know that looking at graviton spin as a perturbable object is kind of out-of-the-box, but I haven't been able to figure out any shortcomings - what do you think about the theoretical underpinnings (apart from the experimental part). If a particle or nucleus is spin-active, then you can write a Hamiltonian for it, particularly if you treat it as a density operator. Optics guys do it for the photon and if the gamma for the graviton really is 2, then the EM field to couple to its spin is clearly somewhere in the Ghz range - any thoughts?

[Martin]

..but, even theoretically, do you think there's a shot? ...

You need somebody besides me to react.

Olaf Dreyer is a young guy, no need to bashful.

You can write him tonight. If you want start off ASKING him about experiments.

Tell him you are an experimentalist and does he know of any approaches to laboratory testing of QG that are being explored.

Tell him you want to get into experimental QG if there is any viable approach.

Ask him who, if anybody, is doing this.

Ask him if there is any chance that such and such graviton resonance etc.

 

Olaf was just a postdoc at Perimeter a couple of years ago. Maybe he is still a postdoc. I don't know how he got connected at MIT. But MIT has a good experimental physics network, Olaf may be connected. He may know things.

Even though he is not by any stretch an experimentalist .

[solidspin]

well, martin -

 

I very much appreciate the suggestion...I'm going to get up the gumption to email him...I would just be floored if I could get a post-doc to pursue this...my advisor thinks I'm daft - she's British (D.phil, Oxford, etc.), but she can't see anything wrong w/ the NMR part and she understands the nature of the tensors b/t the 2 gravitons to achieve a resonance condition (they are purported to be bosons, after all!), as there is a useful pulse sequence we use all the time which is analogous (except the construction of the tensors is dramatically different, but same general formula structure). Awesome - thx again! I'll keep you posted?

[Martin]

I'll keep you posted?

Please do. What I'm afraid of is that he won't respond, of course.

I'd like to know if he writes back.

 

Your advisor, the Brit, is right in a conventional sense as I'm sure you know.

There is a sort of consensus that QG is out of range of lab experiments. So of course you must be daft. Good word. I like daft.

 

But occasionally daft people get onto something. I dimly recall somebody talking about QG and superconductivity. Chinese name. Was at UC Berkeley I think, but moved to the new UC Merced campus at retirement age. Daft perhaps, but possibly very smart. Lab experimentalist.

 

Olaf Dreyer might know who I'm thinking of and spontaneously come up with the name. If you want to play in this game you need to learn about other people who are venturing into it and what approaches they have tried.

 

HAH!!! I found the guy. Raymond Chiao

http://www.ucmerced.edu/faculty/facultybio.asp?facultyid=58

He's over 65 now and his idea may be no good, but look at these qualifications:

"Research Interests:

Raymond Chiao is a professor jointly in the UC Merced schools of Natural Sciences and Engineering. Previously, he was a professor for 38 years at UC Berkeley, where he earned international acclaim (including the Willis E. Lamb Medal and the Einstein Prize for Laser Science) studying nonlinear and quantum optics. At UC Merced, he will pursue a new line of groundbreaking research on gravitational radiation. Chiao received a Ph.D. in 1965 from M.I.T. and a B.S. in 1961 from Princeton University."

 

So my advice is to write Olaf Dreyer a young QG theorist postdoc with wide interests. But also to look up papers by Raymond Chiao on Arxiv or Spires and get acquainted with the bee he has in his bonnet. You know the expression to have a bee in one's bonnet?

Hmm here is a list of links to some of his papers:

http://faculty1.ucmerced.edu/rchiao/2.cfm?pm=113&lvl=3&menuid=117

Edited January 7, 2009 by Martin

[Norman Albers]

Superconductivity, yes indeed. http://www.scienceforums.net/forum/showthread.php?t=25048&page=3 , post#45. Where the radial SOL becomes imaginary there is not propagation. As radius approaches the GR angular momentum radius 'a' (a laboratory-scale dimension) the imaginary parts go to zero and one sees a small negative real speed of light. I interpret this as a superconducting state. In the GR theory [math]a=J/Mc [/math] and so this dimension, like its cousin the Compton wavelength, is inversely proportional to mass. Quantum mechanics shows that angular momentum J is, in all energy realms, quantized to some multiple of [math]\hbar/2[/math].

Edited January 8, 2009 by Norman Albers

[solidspin]

Martin -

 

well, it's funny but NOBODY has approached it from a spin perspective. Even the original GR observations (the eclipse in 1921) can assert that fundamental coupling occurs b/t the photon and the graviton so [p^hat,g^hat] = not 0, meaning some crude commutator b/t the photon and the graviton, right?

 

So, you're right about my advisor, of course. I will tell you that we are in the same lab here @ Stony Brook Univ. where MRI was discovered - we are in the same basement lab that Paul Lauterbur developed his "zeugmatography" which is what he originally called it - funny, right?

 

Fascinating that somebody on this side of the pond is getting into "gravitational radiation" - perhaps you know the really clever story about the JPL researchers who were building Gravity Probe B? Janet something was the lead PI's name...at any rate they needed to measure changes in the three spheres spinning in x,y,z to measure the changes according to GR, based on the curvature tensors, but the obviously couldn't make any marks on the surface. They chose Nb as a surface metal, exploiting the fact that it's spin active (|9/2>), but that @ 4K, Nb^0 superconducts and they saw a "blip" that they couldn't explain on their accelerometer (since the sphere was obviously spinning), but they were under deadline, so they put it aside.

 

Fast forward to 1999 w/ Tajmar and de Matos, two physicists who last I looked were still w/ the Euro. Space Agcy - they reproduced these exp'ts and determined that the "blip" was trillions of times greater than from normal radial acceleration of a spinning object (even superC). Personally, my guess would be that the electrons in Fock space are coupling to the local gravitons...

 

HOOOOOOOOLY cow!!! Thank you thank you!!! I just arXived Chiao!!! His paper for his superC test mass is 12GHz!!!!!!! HOOOLY cow this provided strong evidence to my concept!!!

 

I will definitely take your advice on Olaf Dreyer as well, but this rocks!!! Here's Chiao's paper: http://arxiv.org/abs/0710.1378

 

this is great!!! thank you thank you - he proved my point!!!! jeez this is fun!

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oh, and Norman (norman albers) and I have been fiendishly going on his stuff that he's been producing which dovetails quite well w/ what I've been saying - he's just looking at it from the null geodesic p.o.v., which bends my brain to no end - he is an awesome friend and colleague!

[Norman Albers]

Yeah boy, at best PHYSICS IS ROCK AND ROLL. Mama, don't let your babies grow up to do physics. They'll fill all the blackboards with quantum mechanic statistics.... Better lyrics. solidspin, it would be nice if you didn't have to scan all the way to 100 GHz with old equipment. Three millimeters is short stuff.

Edited January 9, 2009 by Norman Albers

[solidspin]

hey, norman!

 

so, as Elie Cartan elucidated in the 50's (I think) - GR is density dependent, not mass dependent. So, I'm going to be governed by the density of the object, and the B field I use. Just like we do in NMR, the B field determines the Larmor frequency of your equipment, but the quarks and the gamma determine the absolute frequency of the nucleus of interest and how difficult it's going to be to get a signal. For example, tungsten (183W) should be easy - it's |1/2> and pretty abundant isotopically, BUT it's sensitivity relative to proton is five orders of magnitude away from proton! Ugh!

[Norman Albers]

Thanks for the xplaining, solidspin. It sounds like the frequency response gets higher as you muster stronger B-fields, and also responses get stronger?

[scalbers]

Hello all,

 

Interesting discussion. Unsure if this is remotely related - here is an arXiv paper on measuring graviton spin resonance: http://arxiv.org/abs/hep-ph/0006114

[Norman Albers]

High energy stuff: 1,700 and 2,000 GEV are cited by theories with extra dimensions.

[solidspin]

Greetings, Gentlemen -

 

Steve, yes, it's quite relevant - this is what Holstein @ UMass-Amherst theorized, not citing the work you just posted - but thank you very much for it! Notice the decay? Also, this adds fuel to my proverbial fire, as I have cited above in both my assertions and the papers I've proffered.

 

Norman, definitely high-E, but I am skeptical of extra dimensions - remember that limit equation I came up with??? I'd bet a dollar that that's how the "extra" dimensions are actually handled - spassitude, baby! That limit equation offers a perfectly reasonable way, since the curve is piecewise-smooth, of either line-integralling it or linearly recombining it, no? See, for example, the Einstein-Cartan-sciama-Kibble theorem and their treatment of torsion in GR curvature - outstanding...

 

S

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Gentlemen -

 

Steve - the paper you referenced is EXCELLENT. While I fundamentally disagree w/ their String derivations (since 1. they're derivable from simple CE^4 rotation symmetry group and ii) they largely already exist from NMR theory; see: Conc. Mag. Res. 9 (1996) by Hoult, Bhakar (pp277-98), for example. Secondly, and it may simply be a typo, but they represent a transition as |2> -> |2>, which isn't physically possible. A resonance is a transition from |r> -> |s>; |r>-> |r> makes no sense; |r> -> |-r> is a DQ (double quantum) transition, which in NMR theory is classically "forbidden" and therefore has to be moderated by a SQ transition, which according to NMR theory, as applied here, cannot occur, as there's obviously no dipole-dipole transition here (i.e., |1/2> -> |-1/2>.

 

In their defense, however, they DO get the angles correct for theta (see Table 1)!!! They correspond PERFECTLY to the NMR standard 3cos^2theta - 1 = 0. Ironically, I think they missed the rest of the term, however, as the 2nd term in Table 1 is only part of the P4 term...maybe another typo?

[CPL.Luke]

what was it that Holstein theorized? I couldn't find what you were referencing in the thread.

 

I ask out of curiosity as I just finished up a years worth of coursework under him.

[solidspin]

hey, -

 

really? It's: PRD 74, 085002 (2006). Were you post-doc-ing under him??? He's the only author on the paper. Could you be more specific? What did you do? I'm prepping a research proposal for my advisor on this stuff...I just have this driving need to do this as quickly as possible - couldn't be the worst time, either - some idiot delivering N2(g) to our lab this am quenched our 400Mhz magnet this morning by walking right into the B field w/ the tanks. 80L of He(l) to He(g) in under 5 seconds - had the LN2 also boiled off, it could have killed him. It's a $50,000 error - my advisor is completely pissed. Had his helper been in between the tanks and the magnet, they would have crushed him - huge dent in the hull of the magnet - it's now a VERY expensive paper weight.