|Jun24-04, 11:21 PM||#1|
Girelli and Livine strike again
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"
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"
I think it is seminal---the paper will start research
2004 is turning out to be a good year for quantum gravity
|Jun27-04, 05:26 PM||#2|
It's interesting how taking into account a nonzero cosmological cosntant has led the authors to the concept of Doubly deformed special relativity
|Jun29-04, 12:02 AM||#3|
The reference is to unpublished work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"
"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 large-scale 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.
|Jun29-04, 03:19 AM||#4|
Girelli and Livine strike again
Of course not to be confused with the other 'Moffat', also at perimiter institute:http://arxiv.org/PS_cache/hep-th/pdf/0406/0406202.pdf
|Jun29-04, 10:23 AM||#5|
(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.
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 detect---I will look at 0406202, maybe it is related
|Jun30-04, 12:42 AM||#6|
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?
|Jun30-04, 09:44 AM||#7|
special relativity------makes one quantity invariant under transformation, a speed, the speed of light
DSR------makes 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 Kowalski-Glikman who are working together on what they call "Triply Special Relativity"
that seems like a reasonable terminology to me because it makes 3 things invariant----three 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 May----he talked not only about Simplicial Gravity (dynamical triangulation) paper of Renate Loll----he 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 MOND---so 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 energy----and 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 K-G 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.
|Jun30-04, 10:07 AM||#8|
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 re-introduce 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.
|Jun30-04, 10:31 AM||#9|
apologies to D. Oriti.
I should have called this thread "Girelli Livine and Oriti strike again!"
|Jul1-04, 02:18 AM||#10|
the corresponding paper by Lee Smolin and Jerzy Kowalski-Glikman is now posted
TRIPLY SPECIAL RELATIVITY
"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 non-linear extension of the Poincare algerbra, A, which we describe here.
For R->oo , A becomes the Snyder presentation of the κ-Poincare 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."
|Jul1-04, 02:44 AM||#11|
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 controlled---it 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 Triple-Relativity
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 triple-dip, 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, Sanders---a half dozen or so MONDish papers---another part of the motivation for Triply Special.
amazing how all this is getting brought together now
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