The Reference Frame - Latest Comments

Re: The Reference Frame: President is right to veto Martin Putna's professorship

SteveBrooklineMA — Sat, 18 May 2013 11:31:54 -0000

Reminds me of Larry Summers vs Cornel West.

Re: The Reference Frame: Ways to discover matrix string theory

Dilaton — Sat, 18 May 2013 10:26:54 -0000

Dear Lumo,

I will blame the missing proof-reading for everything I dont understand (joking) ... :-P ;-) :-D

(I always scroll through longer articles first to roughly see, what is in them ...)

Re: The Reference Frame: President is right to veto Martin Putna's professorship

Shannon — Sat, 18 May 2013 10:26:04 -0000

And another thing: the EU is now forcing us to extend our Child Benefit to immigrants children born abroad. At the same time a 15% cut down on Child Benefit will take place, indirectly imposed by the EU too... duh.

Re: The Reference Frame: President is right to veto Martin Putna's professorship

Luboš Motl — Sat, 18 May 2013 09:35:55 -0000

Right. It's sort of surprising that our political institutions still don't look like this. Maybe it's because the perception from the Internet isn't representative of the population. If it were representative, almost all people with any influence would match this template, too.

Re: The Reference Frame: President is right to veto Martin Putna's professorship

Shannon — Sat, 18 May 2013 08:50:32 -0000

France has a government full of these Putna's. Today they've legalised gay marriage, they have removed the word "race" -as in ethnies- (in all dictionaries and in the Constitution), journalists use systematically the word "incivility" instead of beating up or damages on property... We musn't name anything that is against politically correctness for the EU.

Re: The Reference Frame: President is right to veto Martin Putna's professorship

George Christodoulides — Sat, 18 May 2013 07:55:57 -0000

nice post.

Re: The Reference Frame: William Happer on CNBC

Eugene S — Sat, 18 May 2013 06:32:33 -0000

Hi Luke, it's not the job of TV interviewers to ask the "smartest" question, they ask questions that would be posed by the "man on the street" if he were in the studio. They did a good job of that.

By the way, CNBC is cable NBC, not the NBC broadcast over the airwaves for free. CNBC has always been business-oriented.

Re: The Reference Frame: Richard Dawid: String Theory and the Scientific Method

Dmitry — Fri, 17 May 2013 23:13:52 -0000

I just had a minute to think of the
"Pi" concept. That “Pi”, which is used in almost any physical
formulae, and probably in all the most fundamental ones. Understanding that I
managed to establish about Pi was so strange, that I started checking
Wikipedia. And found there what I already expected to be found: "Pi IS NOT
PHYSICAL". Ha-ha for me, but how YOU guys tackle you problems, which
supposed to be purely physical, with something that IS NOT physical??? Isn’t
that obvious that the entire concept of “Pi” described in Wikipedia breaks down
at Plank scale? And also breaks down at (large) scales, which have a number of
different concepts of LARGE, capable of breaking Pi down? What’s going on with
you guys, how could you rely on “Pi”, dealing with a matter, which in such an
obvious way DEMANDS from you something more fundamental than Pi, that would fit
apparently THE SAME formulae, but in a PHYSICAL way?? No wonder you’ve spent
like 50 years already and “still trying”! Of course, you could keep on relying
on “no alternative”, but believe it or not, this is a good way to “keep on
trying” another 100 years

It’s very likely even from simply
healthy point of view that “string theory” found the right direction for its
approach. But if 50 years of trying aren’t enough for you, obviously you have
to re-think your approach, and start re-thinking FROM THE MOST BASIC LEVEL! Cancel
“make physics with no physics”! Question “Pi”, question “numbers”, question
calculus and algebra. Make them “physical”. Apparently THEN you’ll get back on
the right track and start DOING PHYSICS RELYING ON PHYSICS.

It’s a shame for Neil Degrasse Tyson to
be incapable of speaking with Brian Greene on appropriate for physicist – and also
for simply educated public - level. BUT EVEN A CARPENTER WOULD CHANGE HIS OWN WOODEN
FLOOR INTO LINOLEUM, IF 50 YEARS WOULDN’T BE ENOUGH TO MAINTAIN GOOD WOODEN
FLOOR. A CARPENTER PROBABLY WOULDN’T NEED 50 YEARS FOR THAT; A COUPLE OF YEARS MUST
BE LONG ENOUGH TO TURN INTO “LINOLEUMER”, WHATEVER.

So, maybe it’ll be useful for you to
think about yourself as of “a simple carpenter”: not as of some kind of “what I’m
saying has no alternative”-like man. Useful for both: you, and for the entire
science. Read literally – progress of the mankind, since exactly science is
responsible for the last thing. Hence only the smartest of all of us must do
science. Do it responsibly!

Re: The Reference Frame: William Happer on CNBC

Luke Lea — Fri, 17 May 2013 21:50:05 -0000

Having listened to the video I was most impressed by the way the IQ of the tv commentators seems to be going down. Or maybe they were just not professionals.

Re: The Reference Frame: William Happer on CNBC

Robert Rehbock — Fri, 17 May 2013 16:23:53 -0000

Your remark reminds me of a decision in a real legal case I am familiar with. The court allowed the physicist to testify about why physics applied to accident shards as a hand went through a pane of glass allowed him to say what relative motions they had at moment of impact but denied him to testify as to why the pattern of blood spray also established this. Apparently the court was not convinced that a physicist could know the behavior of blood spraying from an artery.
Fortunately the court did not require the physician to qualify his expertise in gardening before accepting the same evidence from a physician who said that the spray would behave like coming from a garden hose sprayer.

Re: The Reference Frame: William Happer on CNBC

George Christodoulides — Fri, 17 May 2013 15:39:41 -0000

nice explanation.

Re: The Reference Frame: William Happer on CNBC

anna v — Fri, 17 May 2013 14:15:29 -0000

You must not be aware that real green houses , the ones that grow tomatoes and strawberries buy bottles of CO2 to raise it in the green house up to 1000ppm, for productivity reasons. CO2 is plant food. http://www.omafra.gov.on.ca/en... "Rates of carbon dioxide supplementation are dependent
on the crop response and economics. Flower and vegetable growers may take
somewhat different approaches. In general, carbon dioxide supplementation
of 1,000 ppm during the day when vents are closed is recommended."

If you made the effort to read up on the effect of CO2 on climate you would understand that the sensitivity is grossly exaggerated by the proponents of anthropogenic warming.

Re: The Reference Frame: William Happer on CNBC

Gene Day — Fri, 17 May 2013 13:31:22 -0000

Mephisto,
You’ve got to be kidding.
Here in Northern California we are getting ever increasing amounts of fruits and vegetables from Canada because they are better and cheaper than our local ones and even those coming up from Mexico, which is a big supplier.
Canada is very cold compared to Mexico and labor in Canada is many times more costly than in Mexico. Canada competes effectively precisely because of greenhouse agriculture, which allows more than 1000 PPM of CO2 to be maintained.
You can argue that greenhouses help keep the crops warm, which is true, but without the huge benefit of CO2, those costly greenhouses would not be affordable.
It is pure idiocy to deny the agricultural benefits of CO2. Satellite studies also show that the whole earth is greening and this is, without doubt, due to the increase in CO2.
And I challenge you to provide the slightest evidence of harmful weather changes due to earth’s increased CO2.

Re: The Reference Frame: William Happer on CNBC

Luboš Motl — Fri, 17 May 2013 13:23:19 -0000

Dear Mephisto,

Will Happer is a physicist. It means that he has a working knowledge of the entire Universe and everything it contains. Working knowledge of the important things in the Universe, I mean. ;-)

http://www.youtube.com/watch?v...

More importantly, he doesn't need that knowledge here because what you're asking here is easily solved with elementary basic-school biology and physics, anyway. Physics and biology are being used by intelligent people instead of the crystal balls that people like you seem to prefer.

The greenhouse effect only shifts the temperature uniformly over the globe (that's why it's also discussed as "global warming"), perhaps with some dependence on the latitude and land/ocean, but doesn't make any short-distance changes simply because the CO2 concentration is nearly uniform or becomes uniform quickly.

At any rate, the shift of the temperature due to an extra 120 ppm has been less than 1 deg C almost everywhere. This makes of order 1% or less impact on the growth rate of plants. On the other hand, the CO2 increase has been about 30% which makes about 15% impact on the growth rate of plants. So regardless of the detailed numerical constants, it is absolutely obvious that the direct impact of CO2 on plants as a plant food is more than one order of magnitude more important than any - hypothetical - indirect impact through the effect of CO2 on the temperature.

Cheers
LM

Re: The Reference Frame: William Happer on CNBC

Mephisto — Fri, 17 May 2013 13:09:27 -0000

"1,000 ppm of CO2 would be beneficial for the productivity of agriculture"
---
how can he be so sure? Has he some crystal ball? What if 1000ppm would heat the surface through greenhouse effect and after that change global weather patterns (local changes in precipitation patterns, wind patterns, desertification etc).
I do not know what would happen and I am largely neutral on climate change debates. I am just questioning his certainty. As a physicist, he probably doesnt know much about climate or ecology anyway

Re: The Reference Frame: String theory = Bayesian inference?

anony — Fri, 17 May 2013 10:35:10 -0000

Having read more, here are some additional thoughts. As far as the anthropomorphism, we could do without it, but the idea the d=2 is fundamental in various contexts I don't think is an odd idea. I think the point is that under perturbations in 2-d one is able to adjust their initial inference where as in higher dimensions one is unable to do so. This I think is closely related to the existence to general analytic solutions in 2-d vs no general analytic solution in 3-d (nee 3-body problem). 2-d also comes into play in boosted spacetimes, so it isn't hard to imagine ordinary spacetime as always having agents in a 2-d grid. I don't know if we say that 2-d is universally fundamental, since the paper claims that the so defined 2-d agent space can map to a parameter space which would seem to be more fundamental.

The paper states:

" for each point of Σagent, we get an agent with a corresponding statistical model"

Which seems to suggest that for any point in a boosted spacetime, there exists a M-dimensional statistical model, which can be updated in a smooth way such that all other points agree with the update. This in my mind begins to speak to holography.

From a more "human systems" perspective, I can not help but think of how when we look at the world, we still can build a two dimensional picture in our mind. Any change we encounter can be smoothly incorporated in that image of the world we see. Philosophically its a nice analogy.

As far as some of the statistical comments, when comparing models of several different types (linear, non linear) one makes the comparison by converting the data and predictions to a standard unitized space and comparing the Residual Sums of Squares. The model with the smallest RSS is the better model. I haven't read the previous papers, so I am not fully aware of the specific calculation of posterior probability, but it would seem to be related to the closeness of measured values to actual values (and actual values are only well defined in classical mechanics). The possibility of different agents having different measured values is then a real consideration, so the ability to update inferences seems to be important.

As far as the 2-d being a weakly coupled limit to string theory, I think the map to parameter space is key. The parameter space seems to be more "real" then the agent space, the fact that there is a map between the spaces seems important since one could argue that there is some map from some set of value in parameter space that agents in a 2-d grid will always agree to. The importance of the agents then is that they are the ones taking measurements and building models.

These are just some initial thoughts, hopefully they are congruent.

http://en.wikipedia.org/wiki/R...

Re: The Reference Frame: String theory = Bayesian inference?

T H Ray — Fri, 17 May 2013 09:38:01 -0000

Lubos,

I would think that to the extent string theory is a theory of nonlocal hidden variables, Heckman is correct. It's interesting to me that you would imply that string theory without a general proof may be irrational -- after all, the mathematical proofs that support string theory are what make it a coherent (therefore rational) scientific theory and not just a set of speculative propositions; every aspect of the theory corresponds to (albeit retrodictively) real physical phenomena.

However it is applied, though, Bayesian inference is a slippery slope. It requires a degree of personal belief that some definite probability on the interval [0,1] exists independent of Bernoulli trials. Hence, it is open to the same criticism most often leveled at string theory itself -- lack of specific novel predictions supported by repeated results of experimental tests.
Tom

Re: The Reference Frame: String theory = Bayesian inference?

Luboš Motl — Fri, 17 May 2013 08:04:04 -0000

Very interesting thoughts by Jonathan. My difficulty probably boils down to the fact that I have no deep feelings for things like "stable statistical inference" - isn't the whole thing just a way to visualize points on a world sheets as "people" and giving the quantities in the sigma model fancy anthropomorphic names?

Moreover, if one derives that the world sheet with d=2 is fundamental, it's sort of strange because since the mid 1990s, I/we have viewed the world sheet and their d=2 as an artifact of the weakly coupled limit in string theory.

Re: The Reference Frame: Valtr Komárek: 1930-2013

Casper — Fri, 17 May 2013 06:53:01 -0000

Brought up as anti-Semite then discovering that you are Jew, thats a bummer. Socialist discovering that you prefer capitalist economy, its okay. A beard that shows he is schizophrenic with additional bipolar disorder. Dr. Klaus was right to give him highest Czechian awards.

Re: The Reference Frame: String theory = Bayesian inference?

Luke Lea — Fri, 17 May 2013 06:38:16 -0000

Could it be tautological?

Re: The Reference Frame: String theory = Bayesian inference?

anony — Fri, 17 May 2013 06:36:22 -0000

I want to highlight this paragraph:

"In other words, stable statistical inference selects out two dimensions for the grid of agents. The limiting case where the overall dependence on the number of agents drops out translates to the condition of conformal invariance in the sigma model. As is well known the condition of conformal invariance leads directly to the Einstein field equations for classical gravity. Quantum fluctuations around the background metric arise from fluctuations in the inferred probability distribution. As far as we are aware, this is the first derivation of classical gravity from the condition of stable statistical inference."

My first impression is that this is something that Gauss must of understood intuitively when he developed his least squares approach. The point is that regardless of overall dimensionality, there is always a one dimensional distance that can be defined between any actual value and its inferred value. The Pythagorean theorem is only well defined with root 2, (a la Fermat's Last Theorem). Relativity is based on the extension of Pythagorean theorem to n dimensions (e.g. the collection of two dimensional manifolds).

The following is from the article about least squares:

"Least squares corresponds to the maximum likelihood criterion if the experimental errors have a normal distribution and can also be derived as a method of moments estimator."

The convolution of error distributions must eventually approach the Gaussian distribution per the Central Limit Theorem, so least squares is a very natural approach to inference for systems with large numbers of observers.

I think the paper is worth understanding since while at some level it is apparently intuitive, it does begin to link several different thoughts and concepts (assuming correctness). It does speak to the naturalness of string theory as a limit of predictive modeling, which it should be since linear structures should be possible as limits to inference whenever dimensions are greater than zero.

Is the paper revolutionary? I think unfortunately that despite its keen insight, it might fall victim to the times we are in. We know that some of the things that would have been viewed as revolutionary even just 30 years ago are no longer seen as such, what is more important is assuming correctness, it opens a direct path between physics and statistics, where in the past statistics have been viewed as tool for studying physical relationships and not so much as a integral part of nature. It also reinforces the idea that our mental image of the natural world is the result of sensory based computation (using the term loosely) and our common mental images are natural results of our common genetics leading to common processing of information...e.g. we should expect to view the world the same since we will naturally agree upon the same interpretation of the data sourced from whatever manifold we live in and the general means by which we collect and process data is generally the same since we all share common ancestry.

Excepting any potential flaws in the derivation, a good paper.

http://en.wikipedia.org/wiki/L...

Re: The Reference Frame: Valtr Komárek: 1930-2013

George Christodoulides — Fri, 17 May 2013 06:28:13 -0000

"we go into territory uncharted in human history. after 400 ppm who knows what will happen?" hahahaha

Re: The Reference Frame: String theory = Bayesian inference?

Luboš Motl — Fri, 17 May 2013 05:51:40 -0000

I understand it in the same way now...

Conformal sigma-models are an interesting subclass because they're mapped to "stable inference schemes".

Re: The Reference Frame: String theory = Bayesian inference?

Phil Jones — Fri, 17 May 2013 05:49:20 -0000

Have I got this right: You liberally sprinkle this collection of "agents" around, each one using local(?) observations to construct a statistical model (just fitting some distribution parameters ) then in the limit that this collection of agents becomes continuous, the posterior prob. distribution is given by a path integral of a sigma model action. This suggests that, at least in information geometry terms, the sigma model is somehow fundamental - these agents could be making observations and buidling models of *any* old crap?

Re: The Reference Frame: Richard Dawid: String Theory and the Scientific Method

Colin Wood — Fri, 17 May 2013 05:32:12 -0000

8 TeV nada zip, cue Johnny Mathis, Yes - It's over