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Girelli and Livine strike again 
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#1
Jun2404, 11:21 PM

Astronomy
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PF Gold
P: 23,270

this time they teamed up with Daniele Oriti
Girelli and Livine's earlier paper was november of last year "Quantizing speeds with the cosmological constant" grqc/0311032 it was a neat paper and we had a thread in this forum about it the new paper just came out today Girelli, Livine, Oriti "Deformed Special Relativity as an effective flat limit of quantum gravity" http://arxiv.org/grqc/0406100 I think it is seminalthe paper will start research 2004 is turning out to be a good year for quantum gravity 


#2
Jun2704, 05:26 PM

P: 915

It's interesting how taking into account a nonzero cosmological cosntant has led the authors to the concept of Doubly deformed special relativity



#3
Jun2904, 12:02 AM

Astronomy
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PF Gold
P: 23,270

The reference is to unpublished work they also connect their work to Moffat's "Modified Gravitational Theory as an Alternative to Dark Energy and Dark Matter" http://arxiv.org/astroph/0403266 "The problem of explaining the acceleration of the expansion of the universe and the observational and theoretical difficulties associated with dark matter and dark energy are discussed. The possibility that Einstein gravity does not correctly describe the largescale structure of the universe is considered and an alternative gravity theory is proposed as a possible resolution to the problems." girelli and livine summarize this connection with Smolin/KowalskiGlikman on the one hand and Moffat's ideas on the other in the brief conclusion paragraph on page 17. It got me to read Moffat. 


#4
Jun2904, 03:19 AM

P: 258

Girelli and Livine strike again
Of course not to be confused with the other 'Moffat', also at perimiter institute:http://arxiv.org/PS_cache/hepth/pdf/0406/0406202.pdf



#5
Jun2904, 10:23 AM

Astronomy
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PF Gold
P: 23,270

(they say americans often do not detect brit sense of humor so I may be missing something in my literalmindedness) and BTW thanks for mentioning this paper by Stephon Alexander (Stanford SLAC) and John Moffat and somebody named Manasse Mbonye at Rochester I.T. http://arxiv.org/hepth/0406202 23 Jun 2004 The Gravitational Instability of the Vacuum: Insight into the Cosmological Constant Problem this paper we are looking at by Livine/Girelli is suggesting to look at the CC as arising from a quantum fluctuation producing just a bit of curvature to small to ordinarily detectI will look at 0406202, maybe it is related 


#6
Jun3004, 12:42 AM

P: 915

Though I believed that Doubly Special Relativity and Deformed Special Relativity were different things, today I learned that they are the same thing. Sometimes is confusing to have two different names for the same concept
So Doubly deformed special relativity= 2*2 Special relativity= Fourfold Special Relativity? 


#7
Jun3004, 09:44 AM

Astronomy
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PF Gold
P: 23,270

special relativitymakes one quantity invariant under transformation, a speed, the speed of light DSRmakes two quantities invariant, a speed and a length TSR (alternatively DDSR)makes three quantities invariant these are new things and it is hard to establish new unambiguous terminology and we are in a period of slightly chaotic language about them. the term TSR is from Smolin and Jerzy KowalskiGlikman who are working together on what they call "Triply Special Relativity" that seems like a reasonable terminology to me because it makes 3 things invariantthree quantities look the same to all observers: the speed of light, the Planck length, and the length scale of the cosmological constant.  Meteor you remember John Baez report about the marseille conference in Mayhe talked not only about Simplicial Gravity (dynamical triangulation) paper of Renate Lollhe also talked about Lee Smolin's interest in MOND. then it seemed on SPR that only Thomas Larsson had the alertness to notice the Loll paper and everybody on SPR wanted to talk about MONDso there was this huge noisy conversation about it with everybody giving an opinion the appeal of MOND is that it gives an alternative way to explain the effects of dark matter and dark energy (you may understand better than I, please correct me if I am missing the point) now it seems like TSR (or DDSR) gives a way to get the effect of MOND, maybe, so it could explain observational data without postulating dark energyand maybe using less dark matter too. maybe some dark matter is real stuff actually there and some is just a mond or TSR effect. so I can understand Smolin interest, if he and Jerzy KG are working on something that acts like MOND but has (unlike MOND) an elegant basis that addresses other questions in a less ad hoc way. 


#8
Jun3004, 10:07 AM

P: 915

the dynamical reality of this movement. I think if the general trend to such relevances of theoretical developement can stream along side it, current perspectives being now engaged, " here I woud reintroduce LIGO experiment and Glast, along your current discussion to help orientate how current experiments might be able to valid current perspective in one form or another wtih new model perceptions . It was important to me to show how such model currently shown here by smolin question might have been spoken too, in the uses of measure, two clocks and to identify the original point where this model could expand on. I hope this is making sense. 


#9
Jun3004, 10:31 AM

Astronomy
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PF Gold
P: 23,270

apologies to D. Oriti.
I should have called this thread "Girelli Livine and Oriti strike again!" 


#10
Jul104, 02:18 AM

Astronomy
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PF Gold
P: 23,270

the corresponding paper by Lee Smolin and Jerzy KowalskiGlikman is now posted
TRIPLY SPECIAL RELATIVITY http://arxiv.org/hepth/406276 Abstract "We describe an extension of special relativity characterized by three invariant scales, the speed of light, c, a mass, κ and a length R. This is defined by a nonlinear extension of the Poincare algerbra, A, which we describe here. For R>oo , A becomes the Snyder presentation of the κPoincare algebra, while for κ > oo it becomes the phase space algebra of a particle in deSitter spacetime. We conjecture that the algebra is relevant for the low energy behavior of quantum gravity, with κ taken to be the Planck mass, for the case of a nonzero cosmogical constant Λ =R^{2}. We study the modifications of particle motion which follow if the algebra is taken to define the Poisson structure of the phase space of a relativistic particle." 


#11
Jul104, 02:44 AM

Astronomy
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PF Gold
P: 23,270

Interestingly, Smolin and JerzyKG cite seven or eight papers by Ambjorn and Loll"dynamical triangulation" papers
several lines of research seem to converge here or get interconnected some way it happens in the first paragraph of page 3 where Smolin and KG say their motivation for Triply Special Rel. they say it is already clear that we have to make the planck scale an invariant scale, like c is the speed scale and it is invariant but, they say, it is getting increasingly more obvious that we have to make the cosmological constant scale invariant too then they cite 7 or 8 papers by Ambjorn and Loll et al, because when you do dynamical triangulations the cosm const Lambda plays an important role, something Loll pointed out in her "discrete history" tutorial IIRC. Lambda has to be non zero positive and it has to be controlledit has physical meaning in terms of the simplicial model of the 4D universe It sounds to me as if a concordat is being prepared between Simplex Gravity and TripleRelativity Smolin and KG are saying that their motivation for TSR is that it is not just enough that c be the same for all observers and the planck mass be the same, but look the cosm. const is so basic to modeling the universe that it has to be the same for all observers too! so tripledip, triple treat, triple threat. Sounds great to me! Livine and Oriti and Girelli made it look mathematically nice. Now this next paper of Smolin and KG makes it seem reasonable, necessary and experimentally testable. they also cite Milgrom, McGaugh, Sandersa half dozen or so MONDish papersanother part of the motivation for Triply Special. amazing how all this is getting brought together now 


#12
Jul2604, 08:04 PM

Astronomy
Sci Advisor
PF Gold
P: 23,270

just out
a new Girelli Livine paper http://arxiv.org/grqc/0407098 some more on the SoccerBall problem 


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