Fifth FQXi Essay Contest: It From Bit, or Bit From It?

March 26, 2013

The Fifth essay contest from the Foundational Questions Institute is now underway. The topic is about whether information is more fundamental than material objects. The subject is similar to the contest from two years ago but with a different slant. In fact one of the winning essays by Julian Barbour was called “Bit From It”. Perhaps he could resubmit the same one. The topic also matches the FQXi large grant awards for this year on the physics of information. Sadly I have already been told, unsurprisingly, that my grant application fell at the first hurdle but the essay contest provides an alternative (less lucrative) chance to write on this subject. Last year I did not get in the final but that really doesn’t matter. The important thing is to give your ideas an airing and discuss them with others, honestly.

In last year’s FQXi contest 50 essays were submitted by viXra authors. With the number of viXra authors increasing rapidly I hope that we will increase that figure this year. There has been a change in the rules to try to encourage more of FQXi’s own members to take part and improve the voting. Members will automatically get through to the final if they vote for 5 essays and leave comments. Last year there were about 15 FQXi member essays in the competition and if I am not mistaken only two failed to make the final, so it will not affect the placings much, but it should encourage the professional entrants to enter into the discussions and community rating which cannot be a bad thing.

For many of the independent authors who submit their work to viXra, getting feedback on their ideas is very hard. The FQXi contest is one way that can get people to comment, so get writing. We have until June to make our entries.

Please note that FQXi is not connected to viXra in any way.


Planck thoughts

March 22, 2013

It’s great to see the Planck cosmic background radiation data released, so what is it telling us about the universe? First off the sky map now looks like this

Planck_CMB_565x318

Planck is the third satellite sent into space to look at the CMB and you can see how the resolution has improved in this picture from Wikipedia

PIA16874-CobeWmapPlanckComparison-20130321

Like the LHC, Planck is a European experiment. It was launched back in 2009 on an Ariane 5 rocket along with the Herschel Space Observatory. The US through NASA also contributed though.

The Planck data has given us some new measurements of key cosmological parameters. The universe is made up of  69.2±1.0% dark energy, 25.8±0.4% dark matter, and 4.82±0.05% visible matter. The percentage of dark energy increases as the universe expands while the ratio of dark to visible matter stays constant, so these figures are valid only for the present. Contributions to the total energy of the universe also includes a small amount of electromagnetic radiation (including the CMB itself) and neutrinos. The proportion of these is small and decreases with time.

Using the new Planck data the age of the universe is now 13.82 ± 0.05 billion years old. WMAP gave an answer of 13.77 ± 0.06 billion years. In the usual spirit of bloggers combinations we bravely assume no correlation of errors to get a combined figure of 13.80 ± 0.04 billion years, so we now know the age of the universe to within about 40 million years, less than the time since the dinosaurs died out.

The most important plot that the Planck analysis produced is the multipole analysis of the background anisotropy shown in this graph

Planck_power_spectrum_565w

This is like a fourier analysis done on the surface of a sphere are it is believed that the spectrum comes from quantum fluctuations during the inflationary phase of the big bang. The points follow the predicted curve almost perfectly and certainly within the expected range of cosmic variance given by the grey bounds. A similar plot was produced before by WMAP but Planck has been able to extend it to higher frequencies because of its superior angular resolution.

However, there are some anomalies at the low-frequency end that the analysis team have said are in the range of 2.5 to 3 sigma significance depending on the estimator used. In a particle physics experiment this would not be much but there is no look elsewhere effect to speak of here, any these are not statistical errors that will get better with more data. This is essentially the final result. Is it something to get excited about?

To answer that it is important to understand a little of how the multipole analysis works. The first term in a multipole analysis is the monopole which is just the average value of the radiation. For the CMB this is determined by the temperature and is not shown in this plot. The next multipole is the dipole. This is determined by our motion relative to the local preferred reference frame of the CMB so it is specified by three numbers from the velocity vector. This motion is considered to be a local effect so it is also subtracted off the CMB analysis and not regarded as part of the anisotropy. The first component that does appear is the quadrupole and as can be seen from the first point on the plot. The quadrupole is determined by 5 numbers so it is shown as an everage and a standard deviation.  As you can see it is significantly lower than expected. This was known to be the case already after WMAP but it is good to see it confirmed. This contributes to the 3 sigma anomaly but on its own it is more like a one sigma effect, so nothing too dramatic.

In general there is a multipole for every whole number l starting with l=0 for the monpole, l=1 for the dipole, l=2 for the quadrupole. This number l is labelled along the x-axis of the plot. It does not stop there of course. We have an octupole for l=3, a hexadecapole for l=4, a  dotriacontapole for l=5, a tetrahexacontapole for l=6, a octacosahectapole for l=7 etc. It goes up to l=2500 in this plot. Sadly I can’t write the name for that point. Each multipole is described by 2l+1 numbers. If you are familiar with spin you will recognise this as the number of components that describe a particle of spin l, it’s the same thing.

If you look carefully at the low-l end of the plot you will notice that the even-numbered points are low while the odd-numbered ones are high. This is the case up to l=8. In fact above that point they start to merge a range of l values into each point on the graph so this effect could extend further for all I know. Looking back at the WMAP plot of the same thing it seems that they started merging the points from about l=3 so we never saw this before (but some people did bevause they wrote papers about it). It was hidden, yet it is highly significant and for the Planck data it is responsible for the 3 sigma effect. In fact if they used an estimator that looked at the difference between odd and even points the significance might be higher.

There is another anomaly called the cold spot in the constellation of Eridanus. This is not on the axis of evil but it is terribly far off. Planck has also verified this spot first seen in the WMAP survey which is 70 µK cooler than the average CMB temperature.

What does it all mean? No idea!


Abel Prize 2013 goes to Pierre Deligne, and Milner Prize to Alexandre Polyakov

March 20, 2013

PierreDeligne
The Abel prize in mathematics for 2013 has been awarded to Pierre Deligne for his work on algebraic geometry which has been applied to number theory and representation theory. This is research that is at the heart of some of the most exciting mathematics of our time with deep implications that could extend out from pure mathematics to physics.

Deligne is from Belgium and works at IAS Princeton.

I obviously can’t beat the commentary from Tim Gowers who once again spoke at the announcement about what the achievement means, so see his blog if you are interested in what it is all about.

Update: Also today the fundamental Physics Prize went to Polyakov, another worthy choice.

Update: Some bloggers such as Strassler and Woit seem uncertain this morning about whether Polyakov got the prize. He did. They played a strange trick on the audience watching the live webcast from CERN by running a 20 minute film just before the final award. They did not have broadcast rights for the film so they had to stop the webcast. After that the webcast resumed but you had to refresh your browser at the right moment to get it back. The final award to Polyakov was immediately after the film so many people would have missed it. I saw most of it and can confirm that Polyakov was the only one who finished the night with two balls (so to speak). To make matters worse there does not seem to have been a press announcement yet so it is not being reported in mainstream news, but that will surely change this morning. As bloggers we are grateful to Milner for this chance to be ahead of the MSM again.

I would have done a screen grab to get a picture of Polyakov but CERN have recently changed their copyright terms so that we cannot show images from CERN without satisfying certain conditions. This contrasts sharply with US government rules which ensure that any images or video taken from US research organisations are public domain without conditions.


Oh My God Particle!

March 19, 2013

It would be amiss of me not to jump into the debate about what Michio Kaku said on CBS about the Higgs boson. If you don’t know what I am talking about see the blogs of Sean Carroll, Matt Strassler, Peter Woit, Lubos Motl etc.

The initial case for the prosecution was that Kaku had said incorrectly that the Higgs Boson caused the big bang. If you listen more carefully to the details, he is saying that the Higgs boson could be part of a family of scalars that includes the inflaton responsible for inflation. This justifies that the Higgs boson put the bang into the big bang. It is perfectly true that this could be how it works and despite accusations to the contrary Kaku used the words “think” and “could” to indicate that this was a speculative hypothesis, not settled fact. If you missed those caveats it’s your fault not his.

He rightly stresses that physicists dont like the term God particle used by the reporters but he is not making a great deal out of it. The term sticks because people remember it and it tells them that the Higgs boson is considered important. I think it has been explained enough times that it was a joke and was not intended to be taken literally. If the public still don’t get that then there is no hope for their understanding. Ina any case Kaku is not the one guilty of promoting the usage in this interview.

Motl has covered this in the blog post and I agree with what he says. There is just one thing that I think is worth adding. Kaku says that the Higgs boson could be the trigger that sets the big bang off. This is the part that has led to so much criticism  In the original inflation theory the era of rapid expansion does not start right away when the universe is created. If that is the case then it might be true to say that the Higgs boson puts the bang into the big bang but it would not be right to say that it triggered the big bang. So what is he referring to? The answer I think is a genre of big bang theory in which there is a time before the big bang when it was in a steady meta-stable state. According to these theories our universe was triggered by a transition to another vacuum in which the inflaton is responsible for its rapid growth right from the first instant of the new phase. The theory of eternal inflation is one sub-variety of this type of cosmological hypothesis. Personally I do not favour such theories because they seem to be inspired by a philosophical desire to explain the universe in terms of temporal causality and as I discussed at length in my most recent FQXi essay, that is not my philosophy. Nevertheless it has become a popular class of theory with cosmologists. Ironically Sean Carroll who sparked off this attack on Kaku seems to be one of its biggest supporters.

Matt Strassler criticises Kaku above all for not making it clear which parts of what he was saying were speculative. I invite you to listen to what he said again (see the links to the video on the other blogs). He actually stresses very clearly that “we do not know how or why” the big bang started, but “we think” the Higgs boson may be a key piece of the answer. I don’t think he could have made it any clearer that these are just possibilities.

kAKUcbs

If you are concerned that Kaku seems to think that the Higgs boson is responsible for inflation then be aware that this might actually be the case. Sean Carroll denies that this can be the case and Matt Strassler says that it is unlikely. Motl explains exactly why it could be the case and I remember hearing about this in a webcast talk at Moriond on the same day as some of the new results were being aired. The theory requires an extra coupling between the Higgs boson and the curvature tensor and it has its problems, but then so does every other theory of inflation. The model does at least have the virtue of not requiring other unknown fields. When Strassler says that this version of inflation is “unlikely” he is expressing his own opinion. He claims in a comment that he does not express his own personal opinion without indicating as much, yet here he does exactly that.

Kaku is an eloquent speaker and he knows his subject. He is very careful with his words and knows the kind of angle on a physics story that will get the general public interested. Most people do not have the time to digest the kind of details that are explained at length on some of the blogs, yet Kaku can convey a feeling of our excitement that ordinary people can appreciate immediately. Yes, the basic known facts about the Higgs boson are interesting and exciting too but the more speculative ideas that people are working on are what really gets people to sit up and listen. If some physicists fear that people cannot distinguish between known and unknown facts when words like “could” and “think” are used then they are simply not giving people enough credit.

Science reporting needs to cover the full range of news from the latest experimental results to the wildest new theories being discussed by physicists. If it does not do so then it will not inspire new young scientists to take up research. People like Kaku may not please everyone but they are getting the message across. I am sure he will not be discouraged by boring physicists who simply don’t get it.


Higgs Spin (Is It really a Higgs then, finally?)

March 14, 2013

CERN have a new press release out today while latest results are being presented at the QCD part of the Moriond conference. There are further updates since last week including the long awaited CMS results for the diphoton decay channel. The diphoton rate relative to standard model is now 0.8 +- 0.3, much lower than before and a huge disappointment for hopes of beyond-standard-model physics.

MgamgamCMS

In the press release the CMS and ATLAS spokespeople are quoted as follows

The preliminary results with the full 2012 data set are magnificent and to me it is clear that we are dealing with a Higgs boson though we still have a long way to go to know what kind of Higgs boson it is.” said CMS spokesperson Joe Incandela.

“The beautiful new results represent a huge effort by many dedicated people. They point to the new particle having the spin-parity of a Higgs boson as in the Standard Model. We are now well started on the measurement programme in the Higgs sector,” said ATLAS spokesperson Dave Charlton.

So does this mean that they have officially conceded that it really is the Higgs boson and not some HHiggs-like imposter? The official line is now that “they find that the new particle is looking more and more like a Higgs boson, the particle linked to the mechanism that gives mass to elementary particles. It remains an open question, however, whether this is the Higgs boson of the Standard Model of particle physics, or possibly the lightest of several bosons predicted in some theories that go beyond the Standard Model.”

It’s a bit meally mouthed but nevertheless, most c0mmentators are interpreting this to mean that they have agreed that it is a Higgs boson of some sort.

The crux was the spin measurements which both teams agree disfavours spin 2 with positive parity at a 2 to 3 sigma level. The real Higgs boson has spin zero with positive parity and all other spin possibilities are directly ruled out by the fact that  it decays to two spin-one photons. Negative spin zero is not quite so strongly ruled out but this is not being billed as such an important observation.

particle propertty Can it be determined with LHC run 1 data? Does CERN think it is deterministic for a Higgs boson? current status
Decay modes YES YES WW,γγ,ZZ,ττ observed, bb,Zγ,μμ etc ongoing
Other Production modes NO NO gluon fusion OK, VBF, VH and ttH ongoing
no exotic decay modes NO NO preliminary results from ATLAS
Spin = 0 YES YES spin zero verified to about 2 or 3 sigma in each experiment
Parity = positive NO NO negative parity is disfavoured but not ruled out
W fusion NO NO nothing yet reported
Higgs self-coupling NO NO nothing yet reported

In summary, the things that CERN has decided are crucial for determining that this is a Higgs boson are thankfully exactly the things that can be determined from run 1 but there are plenty of other observations to keep them busy for run 2 and beyond.


CMS diphoton result approved

March 13, 2013

Todays LHCC meeting is currently being webcast and slides are going online here. Colin Bernet presenting the CMS update has confirmed that the crucial diphoton results have now been approved. He said they will be presented at Moriond today but the schedule suggests that it will be tomorrow. This part of the Moriond meeting is not being webcast so we will have to wait for slides to come online for the results.

 


Animated Higgs from ATLAS

March 7, 2013

ATLAS have provided some animated gifs showing the accumulation of Higgs events over time in the diphoton and four-lepton channels. Enjoy.

These dont seem to work in situ on the blog. You need to click on the images to get them to work.

Hgg-FloatingScale-Short2

4l-FixedScale-NoMuProf2

At what date do the Higgs bumps start to look real?

Youtube version:

https://www.youtube.com/watch?v=Ub1gcQW6rMc