- #141
Kevin_Axion
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Awesome! That's probably my dream job, something involving High Energy Physics.
PAllen said:I skimmed a lot of this thread, could hardly read it all. I'm surprised I didn't see anyone noting the following positions which have been raised in other forum threads.
...
In short, there are more minimalist approaches to make progress using current conundrums and unexplained results...
And I see shifting emphasis happening naturally. 'Radical' approaches other than M theory and LQG are being done as well as a growing number of papers on more limited approaches, as above...
Lt_Dax said:Scientists believe in things, but they believe in things based on evidence (and they try to do this even in the fluffy early beginnings of a theory, otherwise there's no justification to call it a theory. Even hypotheses have experimental origin). Religious people believe in things based in faith.
I've seen a couple of threads of yours here, not sure I've seen these specifically. I was using the work 'minimal' in a generic sense, interesting that it might have a more specific sense similar to what I was getting at.marcus said:Hi PAllen,
Its possible some of the "other forum threads" relating to minimalist proposals were ones I started. Are you familiar with what could be called "no-frills" proposals of the following two sets of authors?
Hermann Nicolai and Kris Meissner
Shaposhnikov and friends
That's really interesting, especially if they tackle gravity. Do they have dark matter candidate and any approach for dark energy? (I will look over these references, but can't right away; by look at, I mean understand what I can from the abstract and general logic; I can't follow details of such papers). I am particularly interested in the idea of explaining the major evidence beyond SM with a theory that may not be 'ultimate' but is less of a leap than M-theory. In effect, suppose something like M-theory is the ultimate theory at the Planck scale, yet given the enormous difficulties of completing its formulation let alone understanding how to use it, it could be really worthwhile to pursue more partial theories that make progress on currently known conundrums.marcus said:Nicolai presented his idea at the July 2009 XXV Max Born conference. It was LHC testable, predicted no new energy scales between EW and the Planck scale, required just one new field. No low energy SUSY. No extra dimensions etc. Gravity was not included in the talk, as I recall, but they have described a way to include it elsewhere. The slides are here:
http://www.ift.uni.wroc.pl/~planckscale/lectures/1-Monday/3-Nicolai.pdf
The 40 minute video of Nicolai's talk is here:
http://www.ift.uni.wroc.pl/~planckscale/movie/
The first 5 minutes provides an "executive summary" so you can get the gist without going the whole 40 minutes.
He referred to Shaposhnikov's work, and Shaposhnikov has also cited the Nicolai Meissner papers. Some points of similarity.
marcus said:I've reported on these minimalist initiatives in other threads. So I am curious if these are some of what you were thinking. I haven't paid much attention to Effective Field Theory (EFT) à la John F Donoghue and several others, because I've been interested especially in Nicolai Meissner ideas. There is something more to it---the attempt is to extend the Standard Model, with very little extra, all the way to Planck scale and get something moreover that the LHC could falsify.
Their first paper was written in 2006 and has been followed up by a handful of others, indeed they just posted a new one in October 2010.
Here's the 2006 paper:
http://arXiv.org/abs/hep-th/0612165
A good way to dig up minimalist papers might be to look down the list of the 40 papers that cited it:
http://www.slac.stanford.edu/spires/find/hep?c=PHLTA,B648,312
I've highlighted some bits of your post that interested me especially.
a) The need for quantum gravity at all should be considered subject
experimental verification. Maybe some form of QFT in curved
space is a valid model.
On the other hand, this thread is so devoid of any meaningful content, that it would be best served in its own thread.
Lt_Dax said:A person pursuing a TOE is effectively claiming that the essential features of nature are known, and we just need to develop the correct mathematical apparatus
Fra said:So unificiation is not expected because nature has to be this or that way, but rather because whatever nature is, all information about it must be the result of a scientific process. So the learning process "unifies" all knowledge.
... So I think the feature that no observer CAN know everything, is even the key to unification. Unification by undecidability. Whenever diversity isn't distinguishable, there is unification, not by enlightment but by ignorance.
marcus said:The idea is to do only what is absolutely necessary to achieve the incremental goal of a nonperturbative backgroundless quantum geometry. In other words don't go haring off after a TOE
friend said:... I suspect you will not find those answers without explaining everything else in the process. I think it will take a TOE to explain QG. For if you explain where spacetime comes from to begin with, then you'll probably discover where particles come from that move in that spacetime.
...
marcus said:Friend! You sound as if the game, for you, is to find ultimate answers to the most basic questions!
Ultimately you might well be right that to finally understand the intimate dialogue between matter and geometry one will have to express them as both rooted in a common mathematical ground. As different aspects of the same thing.
marcus said:I want to see how Pallen would separate some issues out. He suggests that QG might not be needed because gravitons might in effect have no universal or fundamental existence---might just be an artificial construct that is perhaps useful for some purposes.
I agree with downplaying the graviton's significance---it doesn't come up much in nonperturbative QG. But that does not remove the need for QG, as I see it. One still wants a quantum spacetime geometry--a concrete mathematical representation of dynamic geometry--in order to do early-universe cosmology.
I guess my bias is kind of gradualist/incrementalist. The spacetime geometry of classical GR fails in the early universe. I want to see some improvements on GR tested. A TOE seems like a red herring, an impractical distracting goal.
I'm afraid of boring you with my list of phenomenologists. I find it exciting that they have taken the bit in their teeth. I just saw that Tsujikawa is on board. He has a paper in prep that says Loop cosmology is falsifiable* by available means: as I understand it, by the next CMB mission after Planck. Planck is now taking data.
We are talking about a bunch of phenomenologists who are not Loop people, and CMB polarization missions with provisional names like "B-pol" and "CMBpol".
Having Shinji Tsujikawa's participation is important, as I see it. In case someone is unfamiliar with him here is his home page at U Tokyo:
http://www.rs.kagu.tus.ac.jp/shinji/Tsujikawae.html
Key people, in my view, are Aurelien Barrau, Julien Grain, Wen Zhao, and Shinji Tsujikawa---together with the people who have co-authored with them on this topic.
*Broadly, not just one particular model or version.
On the other hand, I definitely think string theory is still worth pursuing in the mix. Getting 4 forces without assuming them is not boring to me, it remains one of the high points of my following physics.
Lt_Dax said:@PAllen
I know you don't have the time to respond, just wanted to say I found your post very interesting. I'd like to pick up on the above point if I may. It's a plausible sounding view and I totally agree that models are worth studying because we can learn useful mathematical things from them (AdS/CFT is particularly interesting), but to me the inherent problem is, again, the assumption that we know what the new TOE "needs to do". There could be 7 forces, not 4. Where does that leave us then?
Such a drastic alteration would probably call for an equally drastic revision of what the fundamentals of the model are in order to "predict" the new reality. I find it to be totally suspicious, because that process of revising our view of what we need to predict from first principles could go on forever. There is a better way (and in my view the only real way) to find out new physics; i.e. experiment. Cosmological observations are the way to go, I would think, in the near term future, unless someone figures out how to build an accelerator the size of the universe.
Maybe.Lt_Dax said:I think we agree more than you might think.
I fully agree - inference is evolving (~piecewise) - but if people have taken this seriously, then why doesn't our current theories reflect this inference structure? To me this is significative of lack of some deep insight. (that's not to say that people should have understood 100 years ago what we understand now, I'm just saying that MAYBE time is soon ripe for such insight, although it's still absent)Lt_Dax said:but it is and always has been a piecewise process, not a one shot approach, and above all, an evidence based approach.
Lt_Dax said:If the 'let's try to develop a complete TOE' approach was a worthy method, it would have worked for Einstein. He failed because he had incomplete knowledge. Who are we to claim that things are different now?
marcus said:...
You ask what would happen if String moved to the math department. That might be very interesting! Then it would be competing for jobs, for citations, for seminar attendance, for the hard to define "prestige" that math people confer on each other...
...Actually some string physicists have moved over into the Math Department ... Urs Schreiber ... Now he is in the Hamburg University math dept...
atyy said:
atyy said:Does pure mathematics exist?
Lt_Dax said:...the Lucasian chair has real meaning to these fellows as a mathematical accolade, but it doesn't mean that physics and mathematics are the same subject...