Talk:Loop quantum gravity/Archive 1

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LQG and GLAST

so if GLAST does not observe variance with the speed of light, is LQG falsified?

on the other hand, if GLAST DOES observe such variance, will nobe prizes be handed out?

also what does it mean that LQG does not recover the classical limit? How is it that if you start with General relativity, quantize it, you are unable to recover General relativity?

Nice work

Miguel, nice work today. Thanks. -- Mcarling

Cosmology

The whole paragraph entitled "LQG and quantum cosmology" should be removed. It has nothing to do with LQG, or relativity, or quantum mechanics. These are theories about the physical universe and say nothing about "truth," and terms like "observer" and "measurement" when used in these theories are used in a very specialized and specific way.

People that do not have a full graps of the nature of theories about physics often make such extrapolations about other unrelated philosophical concepts, though the one that I have heard the most is the Uncertainty Principle means that there is no absolute truth; the thing about light cones implying there is no absolute truth is a new one on me. It is even a farther strech, since all light cones mean is that information can propgate through space at a limited speed.

I can assure you that this claim is not made by anyone who has a deep, mathematical understanding of these theories, and it is very misleading to those who do not have a basic understanding of relativity.

I do not want to be mean, but it is annoying to see people make such unjustafiable claims and mislead others.

Three Roads to Quantum Gravity is a cute little book, but it should not be the basis for this article. -- Miguel

• • I'm the dumb guy that made above four paragraphs. First of all, I did not make any changes to the article; I merely suggested them. Second of all, I did not know these were claims were taken from a book made by a theoretical physcist. Trust me, I know theoretical physcists (being a physics undergraduate, a mere undergraduate, mind you) and I do know about people making unreasonable claims about such things as "absolute truth" based on the uncertainty princple and aspects of relativity (e.g.- Ah, this must mean that all things are "relative!") that have been refuted by my professors. I do believe there is a place in physics for philosophy. (For example, the definition of a "measurement" in Quantum Mechanics is still a debated issue, and there are a lot of problems with time that are being consdiered in a phiolosophical manner.) Really, what I thought the statement was was another statement in the form "There is no truth because of x..." I misunderstood it. I sincerely apologize for jumping to conclusions on a matter WAY beyond my knowledge and retracted my comment, especially because it is overly contentious. (And I especially defer to Miguel and the other moderators on this page who have a very deep understanding of the nature of Physics.)

--DGB

I didn't say you're dumb, and I am not disagreeing with you, but I do think you were undiplomatic. Also, the article is originally based on a single person's reading of Three Roads... and it does contain some misinterpretations whicj should be corrected. Finally, I am not a moderator and you should all be bold in updating pages. -- Miguel

---

The set of four paragraph above this is one is rich. The third one in particular asserts that Lee Smolin, professor of theoretical physics and a leading researcher in both LQG and String Theory, doesn't have "a deep, mathematical understanding of these theories."

The anonymous author of the above thereby diminishes his or her own credibility. I am therefore tentatively reverting the other changes made by this person until citations in the literature are provided or Miguel confirms them. -- Mcarling

Gee, I have just been elevated to the rank of "expert" here. Well, like my fencing instructor says, an expert is someone who knows one more thing than you do. Anyway, here's my take on this (for what it's worth) -- Miguel

1. 1. measurement, observers, and other philosophical issues are not irrelevant to quantum gravity.
   2. Lee Smolin knows what he's saying, which doesn't mean that one of us paraphrasing from his popular works will know what we're saying.
   3. Hack away at the article, but don't be contentious. And if you choose to remove material from the article, put it in the talk page.

---

The article says LQG predicts variations in the speed of light with frequency, violating Lorentz invarience. Science magazine, 29 Aug 2003 says that this is true of other QG theories (which have now been disconfirmed on that basis), but not of LQG. Thus, the article seems wrong on this point.

---

Ahem. "Some of the players..."? Please put this article in proper form, with the external link at the end marked as such.

And, add some intro for those who don't know anything about string theory. The casual reader is not going to read through explanations of ten theories that s/he doesn't understand, before reading this. They're just going to read this, because this is the latest and greatest theory, right? Thanks.

Also it's nice to know that LQG avoids the philosophy of science problems by offering disprovable hypotheses. But does it rely on new math - ff so it still has the philosophy of mathematics problems of a very narrow base of proof checkers. And, are there two mathematical models that result in the same perceived physics? If so that opens up the same questions as in string theory re: reality of math in a world presumably 'built on' physics.

---

I made the form charges suggested by moving the list of players to the end and putting the links in list form. I disagree that string theory should be explained in the LQG page. String theory is an alternative approach and is referenced here for contrast and because it is likely to be of interest to those who are interested in LQG. I haven't read every paper in the field, but it seems that LQG has made use of math that was previously known in mathematics, but not in physics. I don't know of any math that was developed specifically for LQG.

---

LQG makes use of techniques that have been standard both in mathematics and physics for decades. It is based on a reformulation of classical general relativity (Ashtekar's "new variables" - also decades old in the mathematical literature) which makes the old idea that general relativity is a gauge theory of the Lorentz group work. All the tools of quantum gauge field theory that proved so successful in particle physics could then be used for quantum gravity.

LQG is a very conservative physical and mathematical theory in many respects, but it is also revolutionary in its implications for fundamental physics and the nature of space-time.

Integration theory on spaces of connections is somewhat new, but the tools are standard functional analysis, direct and inverse limits, and the tools of axiomatic/algebraic/constructive quantum field theory, which had been developed over several decades to make sense of the conceptual problems of quantum field theory.

Some of this stuff will make its way to the main page, I promise.

It is appropriate in a talk page to say that the fact that the theory is relatively successful without introducing extreme amounts of mathematical baggage or extraneous physical assumptions (like supersymmetry) makes it very attractive to people who are tired of string theory. -- Miguel

Theory may be the only thing loopy.

http://www.arxiv.org/abs/astro-ph/0308214

---

The paper above presents experimental evidence suggesting that theories of quantum gravity must not violate Lorentz invariance. It purports to refute those theories of quantum gravity which violate Lorentz invariance at high energies (on the order of 20 TeV). Is LQG Lorentz invariant? I know LQG is diffeomorphism invariant, but I'm not sure about Lorentz invariance. Anyone know? -- Mcarling

The paper also mentions constraints on "large extra dimensions", in case anyone thought String Theory is not affected (grin).

LQG has been used to make calculations suggesting Lorentz violation. Here are some references:

http://arxiv.org/abs/gr-qc/0205103

http://arxiv.org/abs/gr-qc/9909079

LQG is manifestly a gauge theory of the Lorentz group. However, the quantum spacetimes appearing in the theory might not be Lorentz invariant at the planck length. This is an open problem, and not everyone agrees that the two papers I quote are correct. On the other hand, this issue has motivated people to look again at the possibility that Lorentz invariance is not an exact property of out universe. See these papers for an overview of one possibility that people are exploring.

http://arXiv.org/find/gr-qc/1/ti:+AND+relativity+AND+doubly+special/0/1/0/all/0/1

Loop quantum gravity could be formulated by replacing the Lorentz group with a q-deformed "quantum group" (not a group, but a Hopf algebra). This is related to the cosmological constant. Presumably the low energy limit would still be Lorentz invariant, though.

-- Miguel

questions

2003.12.23 19:20 EST

Please forgive me if I breach protocols here. I just read the LQG article in SciAm and have some questions.

1. Is there any research into a relationship between MOND (the discrepancy between observation and prediction of Newtonian dynamics at very low accelerations in galactic disc rotation) and LQG?
2. Does LQG's strength essentially come from sidestepping the mathematical intractability issues of string theory by avoiding the assumption of continuity of spacetime?
3. Are gravitons needed in LQG, or is the gravitational field represented by the structure of spacetime itself?
   1. (From before I knew of LQG) Why are gravitons still expected/predicted if gravity is warped spacetime? And why aren't the other, stronger forces considered to warp spacetime as well? (Maybe they are warping the other dimentions of the 11 predicted by string theory?)

There is a theorem in QFT that states that any operator following certain conditions(such as locality) may be expressed in terms of creation and anilation operators(thus the field may be thought of as the exchange of virtual particles)

They do warp the other dimensions(see Kaluza-Klein theory).

1. What does LQG say about Bose-Einstein condensates, the double-slit experiment, and other quantum "weirdness"?

probably nothing; those are already explained by quantum mechanics

JeffBobFrank 20:59, 24 Apr 2004 (UTC)

And I'd like to make some comments. Most amazing to me is that one of the most mysterious and curious phenomena, gamma ray bursts, are one of the most promising tools for testing LQG. Like the carbon synthesis resonance was for some, this is, to me, almost too much of a coincidence to permit me to keep my atheism!

danw hooya27 at yahoo dot com

corrections

3/6/04

I removed a number of incorrect statements. LQG is not yet known to have the correct classical limit in 3+1 D. I shortened the section on the Kodama state. There were any number of incorrect statements in the comparison section, so I replaced it with something hopefully a bit less tendentious.

singular vs plural

I disagree with singularizing the links to twistors and ashtekar variables. Although one can indeed speak of a twistor, there is no such thing as a single Ashtekar variable. — Miguel 04:41, 2004 Apr 20 (UTC)

I don't know anything about Ashtekar variables, so will yield on that one. But twistor is already existing as a singular article, and it's Wikipedia standards to use singular article titles wherever possible, so I'd prefer to leave that one changed. Bryan 04:43, 20 Apr 2004 (UTC)

This is not about arguments of authority ;-)

Ashtekar variables are "a self-dual spin connection and a triad", which boils down to three real vectors and a complex 2x2 matrix at each spacetime point. The whole collection is referred to as "Ashtekar variables", so the singular denomination is clearly inappropriate. — Miguel 04:59, 2004 Apr 20 (UTC)

The Wikipedia policy is to use the singular form except where the usual noun form is a plural, e.g. scissors, pants and electronics. You have to use your judgement as to whether it should be plural in this case. Google returns 20 times as many results for the plural form. I don't know about ashtekar variables, but I'm quite sure there's nothing wrong with using the singular form of twistor. -- Tim Starling 05:17, Apr 20, 2004 (UTC)

Wilson loops and spin networks section

I don't like the Wilson Loops and Spin Networks section at all. Any suggestions for improvement? — Miguel 20:27, 2004 Apr 24 (UTC)

I think this article could really use some nice diagrams of the graphs and "spin foam" that this theory's all about, showing how time and space are quantized. The recent Scientific American article on loop quantum gravity seemed to have some very good diagrams, to my admittedly untrained eye; they gave me a somewhat intuitive grasp of the basics (which I hope is correct :). Bryan 20:54, 24 Apr 2004 (UTC)

You would hope that Lee Smolin would do a good job of explaining the intuitive interpretation.

I think I should go in and write Wilson Loop to begin with. After what I wrote in the history section, I think the current Wilson Loops and Spin Networks looks grossly inadequate. — Miguel 20:55, 2004 Apr 24 (UTC)

Wilson Loop is currently orphaned, and needs some knowledgable person to stitch it into the fabric of the wikipedia in the right place. -- Finlay McWalter | Talk 21:28, 24 Apr 2004 (UTC)

fixed. After some redirect fun, it's linked from Loop quantum gravity now. --

We need an administrator to move the page to Wilson loop and make Wilson Loop a redirect to Wilson loop (with the proper capitalization: my mistake). — Miguel 21:35, 2004 Apr 24 (UTC)

Will do. -- Finlay McWalter | Talk 21:37, 24 Apr 2004 (UTC)

Done. -- Finlay McWalter | Talk 21:41, 24 Apr 2004 (UTC)

Structure, diagram

As more sections are added to this article, it's becoming rather ungainly. Can I suggest grouping some of the related subsections into a larger one - I'm particularly suggesting grouping all the "LQG and XXX" into some section called something like "Implications of LQG for other physical theories" or somesuch). And while I realise I'm not going to get a photo, is there any chance of getting a diagram of something (I'm really thinking from a shallow aesthetic perspective). Thanks -- Finlay McWalter | Talk 23:55, 30 Apr 2004 (UTC)

How about this image? I'll ask my advisor for permission to upload it to Wikipedia. — Miguel 05:38, 2004 May 1 (UTC)

Sure (providing it's actually helpful). The Tuftian in me says "colour is good" but equally "only meaningful pictures are worthwhile. And I understand absolutely that scientific visualisation, even of stuff far more concrete than LQG, is hard. -- Finlay McWalter | Talk 19:06, 1 May 2004 (UTC)

What do you mean "provided it's actually helpful?". Like it or not, that is what a spin network _is_. — Miguel 14:49, 2004 May 2 (UTC)

I meant it to moderate my own request for a picture, to make it clear that I wasn't asking for any old picture that might just look nice. I'm in no position to judge whether a given picture or diagram is infact helpful. -- Finlay McWalter | Talk 15:36, 2 May 2004 (UTC)

The question is, helpful to whom. Given what you know and don't know about physics, geometry, and spin networks, what does the picture need to do to be helpful to you?

Check out Greg Egan's website. Do you find that helpful? Could you incorporate its content into the article?

— Miguel 22:19, 2004 May 2 (UTC)

Fotini

Anonymous user 64.63.220.180 basically pasted the content of Fotini Markopoulou-Kalamara into the mathematics section of the article. I am removing that. — Miguel 05:07, 2004 May 4 (UTC)

yeah i wanted to have something to say, but i added "more stuff to be added later"

Lubos Motl

hey miguel, if you read lubos motl's article here on wiki

He has a presence on the Internet, where he often participates in discussions and flame wars between loop quantum gravity and string theory

FLAME WARS

Look, I read s.p.r. sometimes and I used to read it regularly when Motl was around. He got in debates with people because s.p.r. is a haven for those who dislike string theory and he is very uncritucal about just how successful string theory is in terms of actual contact with experiment or even the standard cosmological model or the standard model of particle physics. But I would not characterize the exchanges a flame wars. People did not go around insulting each other, and s.p.r. is moderated. You just can't get involved ina flame war with a newsgroup moderator like the article used to claim. I prefer to just state the fact that vigorous discussion took place and that his dissatisfaction with s.p.r. led him to create s.p.strings. Also, he was genuinely interested in getting the facts straight. When Baez started advertising a connection between the Immirzi parameter (which string theorists were fond of as an embarrassment of LQG) and some observable physical quantity from General Relativity, Motl took it seriously and got a paper out of it.

There are too many anonymous users adding controversial statements to this article. — Miguel 21:01, 2004 May 10 (UTC)

actually miguel, "too many anonymous users" it's just one person, *me* mostly who made virtually all the new articles, and virtually all the subsections, but virtually everything i've written i can show there is support for it (i.e scientific american, 3 roads to quantum gravity, etc.). my name is Dan by the way :) i'm not registered though, and QG and Gospel of Thomas are the only topics i'm currently interested in.

by the way "Lumidek" i bet is Lubos Molt, b/c he's the only one who knows it's spelled Motl, and cares enough to re-spell Molt to Motl, and would know about the "heated debates" - that john baez is the moderator, about proving the imizi parameter, etc.

Amusingly, you are actually right about this, Google dixit. — Miguel 23:47, 2004 May 10 (UTC)

Don't be silly, anyone who reads s.p.r. knows his name is Motl, knows about the heated debates, and any wikipedian would care enough about the misspelling. — Miguel 23:25, 2004 May 10 (UTC)

Also, review the edit history: I was the one who mentioned that Baez is a moderator, and the bit about the Immirzi parameter. Just because I think that Motl has a big mouth doesn't mean that I agree with the way the polemic on s.p.r. was described. — Miguel 23:29, 2004 May 10 (UTC)

FLAME WARS VERSUS VIGOROUS DEBATE

"Just because I think that Motl has a big mouth" LOL - that's for sure!

When Lubos Molt aka "Lumidek" wrote HIS OWN BIOGRAPHY here on WIKI, he characterized the "vigorous debates" on sci.physics.research as "FLAME WARS", here on WIKI the "vigorous discussions" between Trovalds and Tannebaum has been characterized as "Flame Wars"

Care to denounce Lubos Motl as a vanity page on Wikipedia:Votes for deletion? I don't. Be warned that a VfD by an anonymous user would look suspicious of ulterior motives anyway ;-) — Miguel 14:51, 2004 May 25 (UTC)

http://en.wikipedia.org/wiki/Kernel_(computers)

"In the early 1990s, monolithic kernels were considered obsolete. The design of Linux as a monolithic kernel rather than a microkernel was the topic of a famous flame war between Linus Torvalds and Andrew Tanenbaum; a summary is available online. There is merit in both sides of the arguments presented in the Tanenbaum/Torvalds debate. "

Miguel, care to edit this page to change "flame wars" to "vigorous debates?" personally when i call something a "flame war" i also mean it as "vigorous debates"

A flame war is an acrimonious debate involving insult, provocation, and/or hostility. Certainly vigorous debate and flame war are not synonymous.

However, I retract my previous statement that you just can't get into a flame war with a newsgroup moderator. It seems that Lumidek's style as moderator of sci.physics.string includes using his moderator comments to flame people ;-)

—Miguel 14:51, 2004 May 25 (UTC)

hi miguel

it's me dan. i don't know how to register. i got a couple of points

1. lubos molt's bio seems impartial so i wouldn't vote it for deletion, although he did describe his own "debates" with john baez/steve carlip as "flame wars"
2. if you read trovald and tannebaum's debates, i would not describe them as "acrimonious" and "invovling insults and/or hostility", it was quite academic and intellectual between monolithic and microkernels, and computer scientists have studied the merits of both positions, but a lot of geeks fondly and AFFECTIONATELY describe these vigorous debates as "the flame wars of tannebaum and trovalds."
3. i've spoken to john baez, and uh calling lubos molt a big mouth is an understatement LOL. he defends string theory and attacks LQG with a religious passion.
4. there was a false post on sci.physics,sci.physics.research that was falsely attributed to John Baez. I cut and pasted it on lubos baby, sci.physics.strings, because i thought and honestly mistaken that it was by john baez, and he tore it apart. you could say he flamed john baez. when johh baez said the article wasn't his, lubos apologized, but every sentence he tried to pin the blame on me :(
5. if you read how he (lubos) "debunks" lqg, a reasonable person would have to characterize it as "acrimonious" "involving insults and/or hostility". among other things he stated on a post he wish LQG would just wither and die, and that it is an "anything goes" approach to physics.
6. recently lumidek aka lubos molt, edited this page. i've read so many of his posts on sci.physics.research and strings, and i've written many of the articles, that it's easy for me to spot his additions and emendations.

i suspect they suffer from NPOV. they are exactly the things he's posted on sci.physics.research.

his emendations and additions I've put in quotatation marks.

"and stringy papers outnumber loopy papers by a factor of roughly 50:1."

He conveniently forgets to point out that LQG is mostly stablished at the level of rigour of mathematical physics, as opposed to string theory, which is established at the level of rigour of physics. — Miguel 03:35, 2004 May 27 (UTC)

"Mathematically, the theory is modelled after Riemann's metric geometry, but the Lorentz group of spacetime symmetries (an essential ingredient of Einstein's own theory of special relativity) replaces the group of rotational symmetries of space."

I think I might have written or substantially expanded on that. — Miguel 03:35, 2004 May 27 (UTC)

"It is not clear whether an approximate Lorentz invariance can be recovered in LQG at long distances and whether LQG can explain the plethora of successful experimental tests of special theory of relativity."

Forgets to point out that LQG is manifestly a local gauge theory of the Lorentz group. — Miguel 03:35, 2004 May 27 (UTC)

"Despite the broken Lorentz invariance, LQG is formally background independent. The equations of LQG are not embedded or presuppose space and time (except for its topology that cannot be changed),"

This reflects a philosophical view that gravity is the very geometric fabric of space and time, and that a quantum theory of gravity must be a quantum theory of space and time "while all other particles and forces must be independent; LQG predicts that unification of forces can never occur."

LQG does not purport to be a theory of everything, just a theory of quantum gravity. The onus is on String theory, which does make such grandiose claims.

Unification has not been observed, and there are some indications that it migt not even be there (the original error bars on the renormalization group beta functions for the different forces have shrunk to the point where unification can no longer be expected from low-energy phenomenology). The quest for unification _is_ a philosophical prejudice. — Miguel 03:35, 2004 May 27 (UTC)

Additionally, the spectrum of radiation of particles emanating from the event horizon of a black hole has been calculated from LQG's theoretical framework and precisely predicted. "Unfortunately, this prediction strongly disagrees with Hawking's semiclassical calculation."

Modulo the immirzi parameter, which is the only free parameter of LQG, it matches it on average, and additionally predicts a fine structure to it, which is 1) experimentally testable; 2) potentially an improvement (to use a semiclassical calculation so far unconfirmed by experiment as a benchmark for an exact nonperturbative fully quantum calculation is a stretch, methinks). — Miguel 03:35, 2004 May 27 (UTC)

LQG in its current formulation predicts neither supersymmetry or additional spatial dimensions, "nor anything else about particle physics"

LQG does not purport to be a theory of particle physics. It does not require supersymmetry or extra dimensions, but can accommodate them. Lubos seems to fail to grasp that LQG is at its core not an alternative to strings but an alternative to "perturbative quantum field theory on a fixed background". — Miguel 03:35, 2004 May 27 (UTC)

"Unlike particle physics and string theory, a theory that follows the principles of natural science and whose assumptions can be studied critically, LQG insists on various assumptions that cannot be questioned."

-- dan

I should add these comments of mine to the article, but I don't have time! I have a dissertation to write and an academic year to end. — Miguel 03:35, 2004 May 27 (UTC)

Hi, dan!

Small world -- you're the dan that posted Sarfatti's stuff to s.p.s, which got Miguel looking here, causing him to point out Lubos Motl to me, and then when I look deeper into controversy surrounding User:Lumidek, here you are again! ^_^

If you want a username, the follow the link "Log in" at the top of the web page. You only need to pick a new user name -- the email stuff is entirely optional. You don't need a user name, but they're very convenient.

I agree with your characterisation of the Linus/Tannenbaum "flame war" -- see my edit to Kernel (computer science) (and my edit summary -- follow the "Page history" link to see this).

Most of Lubos's edits to this page seem OK, but I did change the one that I found to be egregious. You can do that too; edit wars are bad things, but most people go along with it when you edit their contributions. If not, then talk to Lumidek about it here (politely, of course ^_^).

-- Toby Bartels 01:14, 27 May 2004 (UTC)

Hi Toby!

LOL if miguel were to post his response to lubos/lumidek those response line by line LQG article would be much better! :P

if you read Joao Magueijo's, a Spanish physicist like miguel, book faster than light, a book lubos dismisses (flames?) both the content and the author, he said that both "camps" are liken to religious fundamentalists! lubos' attacks on LQG both on sci.physics.research and here and his advocacy of strings reminds me of how christian evangelicals "discredit" other religions and promote their own. of course, i've seen this sort of think in mac versus windows, amd versus intel, ati versus nvidia, CISC versus RISC, etc. but mostly in Christian fundamentalists/evangelicals.

Magueijo is Portuguese!!! A fair number of portuguese might want your head on a platter if they found out that you thought a prominent portuguese was from Spain ;-) — Miguel 06:51, 2004 May 27 (UTC)

anyone who critiques or questions string theory uh well here's lubos, ahem "vigorous debates" on amazon.com

Lubos says, "Let me start with science. Joao Magueijo's theory is unimpressive - in fact, let's admit that it is silly. The author has showed that he has no idea what relativity means....It is sad that the people like Joao Magueijo can get a job ("reader") in Europe...Unfortunately his knowledge of physics is poor and he has nothing real to contribute. In my opinion, he should not have earned a PhD in physical sciences. In fact, he is much more interested in his being visible than real science....the competition in the U.S.A. is simply much tighter, and arrogant crackpots similar to Joao Magueijo would have a very small chance to get a job in the States. Although one should also say that Joao Magueijo has made it to the New York Times. Well, the journalists like sensations and they're not always able to distinguish whether there is some real idea behind the sensation or not. Unimpressive"

Lubos' ability to embarrass himself by engaging in personal attacks never ceases to amaze me. — Miguel 06:51, 2004 May 27 (UTC)

Lubos, while moderator of strings, spoke of John Baez "criticism" of string theory (which was really by jack sarfarti) among other things as having "limited intelligence" and Sheldon Glashow mild criticism's of string theory as "slightly narrow-minded."

one reviewer of this book said "His theory could knock down two solid pillars of cosmology--inflation and relativity. Not only does his radical notion deserve a trial by fire, it also deserves a champion like Magueijo, who isn't afraid of the flames. --Therese Littleton"

as far as flame wars, language is a very flexible and evolving tool. perhaps the flame war wiki article should be edited as many use "flames" in a much broader sense. the term "never constructive" is too strong.

i recognize it must feel rather disappointing to invest one's life in the wrong theory and both LQG and string theory makes enormous academic demands on its researchers. personally after reading all of lubos, ahem "rigorous debates" i've been hoping that (a) supersymmetric particles are not discovered in 2007 at Europe's LHC, and (b) violations to Lorentz invariance is observed by GLAST also in 2007. of course, any combination of a and b could be falsified or verified. 2007 may be a watershed year for Quantum Gravity.

Focus on LQG

Let's stop discussing Lubos and start discussing LQG, shall we?

By the way, this talk page is now over 31 Kb. Time to archive?

— Miguel 06:57, 2004 May 27 (UTC)

hi miguel

"Magueijo is Portuguese!!! A fair number of portuguese might want your head on a platter if they found out that you thought a prominent portuguese was from Spain ;-) — Miguel 06:51, 2004 May 27 (UTC)"

it's great to see that quantum gravity hasn't removed your sense of humor LOL

"Let's stop discussing Lubos and start discussing LQG, shall we? "

of course.

i added several subsections, such as space atoms, time, kinematics, where to study LQG at the graduate or doctoral level, etc. i cut and pasted the section on wilson loops, which you removed, to the "space atoms" section, expanded the section on experiments to include both GLAST and LHC, added remarks by Brian Greene. i also offered an alternative explanation to the 1:50 ratio papers lubos cites.

personally though i wouldn't commit my post-bachelor graduate studies either to string theory or LQG, until experimental evidence comes in, esp. the evidence from 2007 to 2010, and then commit to whichever is most strongly supported by the experimental evidence.

Moved from article

I think most of the following content belongs more properly in quantum gravity. Also, time for me to work more on the spin network page. Wilson loop looks ok. — Miguel 08:14, 2004 May 28 (UTC)