Sunday, July 05, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

\({\rm SmB}_6\) seems more stringy than a plain topological insulator

Natalie Wolchover wrote an interesting Quanta Magazine article

Paradoxical Crystal Baffles Physicists
about a research direction in condensed matter physics that is important for many reasons – and the apparent links to AdS/CFT are among them. Suchitra Sebastian, a female Indian physicist, and 15 co-authors (Cambridge UK, Florida, New Mexico) just published some experimental findings in Science. She claims that the crystal of samarium hexaboride \({\rm SmB}_6\) – named after the six boring Greek Samaritans who discovered it ;-) – behaves in even stranger ways than previously believed.

This seemingly boring crystal has been known to behave as a topological insulator at low temperatures. The crystal structure is simple: create a cubic lattice out of samarium atoms. And in each cube (which may be associated with one samarium atom at the left lower front corner), place an octahedron with six boron atoms at the vertices.

Saturday, July 04, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

What is string theory? Ask Ashoke and Nima

If you have 94 spare minutes, you should watch this insightful and amusing panel discussion on "What is string theory", a public event that took place on Monday, at the end of the Strings 2015 annual conference in India.

Rajesh Gopakumar introduces the two main heroes, Milner Prize winners Ashoke Sen and Nima Arkani-Hamed.

In 863, Greek brothers made Slavs literate

Congratulations to the American readers – 50% of the TRF community. It's The Independence Day, July 4th. This day is followed by two Czech national holidays, July 5th and July 6th.

On July 6th, 1415, i.e. 600 years ago, top Czech Catholic priest, master at my Alma Mater (Charles University), and early church reformer Mister John Huss was burned at stake during the Council of Constance. The top European Catholic apparatchiks didn't like that he has loved the truth and articulately criticized them for their hypocrisy, excessive wealth, double standards during masses, and bureaucratization of the church.

Huss is also the author of the (early version of) Czech diacritical signs (as in "žluťoučký kůň šíleně úpěl ďábelské ódy" which means "a yellowish horse was terribly moaning devilish odes") which became the standard script in the Czech lands, Slovakia, and the Yugoslav nations. The judicial murder led to the Hussite Wars, an era in which the Hussites – terrorists who were his self-appointed followers – were establishing communist cities, plundering Europe, constructing "simply clever" new kind of weapons, and singing combat songs that made the Germans šit into their pants. Most Czechs are proud about the Hussite period that ended by the Hussites' 1434 defeat at the Battle of Lipany.

The Pope and the German president recently apologized for the judicial murder of this "heretic" and offered us 1/2 of the Vatican and all of East Germany as a modest compensation.

Friday, July 03, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

David Gross', Nobelists' painful AGW publicity stunt

Sixty years ago, on July 15th, 1955, Max Born, Werner Heisenberg, Hideki Yukawa, Otto Hahn, and 14 other Nobel prize winners signed the Mainau Declaration against the use of nuclear weapons. It was a decade after Hiroshima and Nagasaki and the fear made sense. The superpowers had accumulated lots of nukes and their destructive character had been observed.

These days, there is another meeting of the Nobel laureates at Lindau. Nobel prize winners including David Gross performed something that cynics in Deutsche Welle call "a stab at relevance" or "a publicity stunt": the 2015 Mainau Declaration on "climate change" (see the PDF file with the declaration).

Brian Schmidt, the 2011 Nobel prize winner in physics for his (and their) experimental discovery of the dark energy, became the spokesman for this publicity stunt. David et al., don't you feel a little bit painful? Or, more precisely, too painful?

Sir Nicholas Winton won't get his Peace Nobel Prize anymore

Sir Nicholas Winton died on July 1st at age of 106+ years (respiratory problems). He has been repeatedly nominated for the Peace Nobel Prize but the committee has repeatedly chosen someone else, often someone profoundly unworthy.

The British press has nicknamed him the "British Schindler", a German guy who saved about 1,200 Jews by employing them in his factory. Winton has saved 669 Czechoslovak children, mostly Jews, by organizing (one big train in) the so-called "Kindertransport".

Thursday, July 02, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Introduction to double field theory 1/2

Guest blog by Olaf Hohm of MIT

First of all I would like to thank Luboš for giving me the opportunity to write a guest blog on double field theory (previously mentioned here).

This is a subject that in some sense is rather old, almost as old as string theory, but that has seen a remarkable revival over the last five years or so and that, as a consequence, has reached a level of maturity comparable to that of many other sub-disciplines of string theory. In spite of this, double field theory is viewed by some as a somewhat esoteric theory in which unphysical higher-dimensional spacetimes are introduced in an ad-hoc manner for no reasons other than purely aesthetic ones and that, ultimately, does not give any results that might not as well be obtained with good old-fashioned supergravity. It is the purpose of this blog post to introduce double field theory (DFT) and to explain that, on the contrary, even in its most conservative form it allows us to attack problems several decades old that were beyond reach until recently.

The Hindu: an interview with Ed Witten

A big portion of the world's string theorists gathered in Bengalúru, India last week. The local newspapers have published a couple of stories – e.g. about Ashoke Sen etc. One fresh interview in The Hindu is titled

‘Supersymmetry may show up at the new run of LHC’
Šubašrý Desikan has talked to Edward Witten who was introduced as the "world's only physicist who has won the Fields Medal".

Much like in most interviews since 2006 or so, the first question was a deeply unoriginal one about the empirical character of string theory. Witten answered that physicists are interested in string theory because of its elegance and especially because it seems to be the only way to reconcile the two pillars of the 20th century physics, quantum mechanics and general relativity.

Wednesday, July 01, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Tsipras' surrender letter: the timing of a loser

To sell while you are crumbling is too late

Twelve hours ago, at midnight Prague Summer Time, Greece became the first country that defaulted to the IMF among the countries that were widely considered developed at the moment of the default. I have been 90% sure that this event was unavoidable at least since June 5th or so. People who claimed that the European politicians "wouldn't allow" something like that have been shown spectacularly wrong.

Some EU politicians may religiously worship the memes about the integrated Europe. But these politicians have neither the absolute power nor the bottomless wallet. They face many people – including important people – whose thinking is more realistic. Even more importantly, they face the laws of physics. The convergence of Greece towards the collision with the default was as guaranteed as the implications of the laws of gravity. People just won't pay €1.6 billion for free – and that was the only way how Tsipras and comrades wanted the money to be paid. A few cheesy clichés about Europe's unity won't make anyone throw €1.6 billion into a black hole that has been known to be black for 5 years or so.

Tuesday, June 30, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Memories, asymptotic symmetries, and soft theorems

Last Monday, the Strings 2015 annual conference started in Bengalúru, India. Now it's over. With three exceptions, the written documents used by the speakers are posted on the page with talk titles and videos. Unfortunately, most of the videos have still not been posted; the last released ones were added 4 days ago.

(Update July 1st: thank God, the videos are available.)

There have been numerous interesting talks at the conference. Some of them are nice reviews. In order to focus on talks with a truly new original content that is sufficiently conceptual to be appropriate for a semitechnical blog, let me pick Andy Strominger's talk (PDF), not only because Andy celebrates his 60th birthday in a month.

Monday, June 29, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Puerto Rico and Greece: a comparison of two defaults

Excessive pensions and similar expenses are always the main problem

The center-left populist government of Puerto Rico just announced that the islands (one big plus many small ones) won't be able to repay their $70+ billion public debt. These announcements just happen to come at the same time when Greece is expected to go bankrupt (tomorrow in the evening). It's tempting to compare these two economies.

I think that there are some huge differences as well as some amazingly accurate similarities – both of which are being heavily underestimated. Let us look at those.

First, just to be sure, Greece is a country in Southwestern Europe (in the Balkans), very close to Asia and Africa, and it's been considered the weakest link of the European Union and the Eurozone for many years. On the other hand, Puerto Rico is an island East from Cuba that has been governed by the U.S. federal government since the 1930s but it is not officially incorporated as a state. We may say that Puerto Rico is the weakest link of the U.S. – and the U.S. dollar zone.

To summarize, these two defaulting entities have totally analogous relationships to their larger umbrella territories or currency areas. I believe that many Americans who tell the Europeans that Europe "should" bail Greece out again totally fail to realize that their relationship with Puerto Rico is totally analogous. If it's right for Europe to bailout Greece again, the U.S. government should surely bailout Puerto Rico as well, shouldn't it? One could argue that Puerto Rico is politically "closer" to the government in D.C. than Greece's solidarity distance from Berlin, Helsinki, Bratislava, or even Brussels. Puerto Rico's main leader "is" Obama in some sense – but the Greeks' main leader is neither Merkel or Hollande nor Tusk or Juncker.

Sunday, June 28, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Gay marriage: constitutional revisionism is extremely dangerous

I have nothing against gays. My co-existence with gays has been very good and dozens of witnesses exist to confirm my extraordinary tolerance, to say the least. I think that there are biological reasons for gays' inclinations and these inclinations are compatible with their life or individual health.

A part of my understanding of the human freedom implies that people may insert their organs wherever they want – as long as they don't harm the freedom and dignity of others. And in a democratic system, voters or their elected representatives may ensure tax breaks for those who insert these organs at the right places. The desired frequency and locations may be specified in the illustrations embedded in the laws.

I won't think that they are wise if they do such things but nations surely have the right to establish their internal rules according to their tastes. In general, people in Czechia are extremely tolerant about these matters. Since 2006, we had "civil unions" for gays. But on the other hand, there exist virtually no "enthusiastic advocates" of homosexualism in my country, no "warriors" arguing that the unions have to be called "marriages". We may be just too mature or phlegmatic for such simple new forms of religion. Since the age of 10, Czechs generally know how babies are created etc.

But what I find unacceptable is the rewriting of the meaning of words and the meaning of laws and constitutions designed to achieve certain political goals.

Saturday, June 27, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Referendum about survival 5 days after death?

During the night, the world has learned about a shocker. It is the first one among the "unpleasant and unexpected Greek surprises" the world may face because it was incapable of forcing Greece into formal bankruptcy at a moment chosen by the creditors – not by Syriza.

A model of Greece's behavior in coming days or weeks

Alexis Tsipras scheduled a referendum about the creditors' proposals on July 5th. If the date were different, it could be interpreted as an effort of the cowards to get rid of their duties and their responsibility. With the referendum, they could say: It's the nation who screwed itself, isn't it?

However, the problem is that the referendum is supposed to take place on July 5th. Unless Syriza 100% surrenders in about 80 hours – and it's been suggested that the actual time that remains is shorter – Greece will be in the IMF arrears since July 1st.

By the IMF rules (although not by the rules of the rating agencies), it will be in the state of bankruptcy. The European Central Bank will be forced to withdraw the support for all the Greek commercial banks. Those will collapse. The country will completely run out of hard cash. The circulation of the hard currencies will stop.

The country will be effectively out of the Eurozone whether or not the elimination will be formally announced by that time.

Friday, June 26, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Muslim world is unsafe for Western tourists

Three Islamist attacks took place today. Some injuries in a mosque Kuwait, a beheaded manager in a U.S. company in France; and 28 or more people shot at a beach in Tunisia.

Beheading looks scary but I am obviously much more shocked by the Tunisian beach. I/we have been to Tunisia twice, in Summers of 1997 and 2008. I think we were in Sousse – the place of the attack – in 1997. And it was certainly Tabarka in 2008.

Quantum computers won't end people's confusion about quantum mechanics

On his blog Štetl optimized, MIT complexity theorist Scott Aaronson announced an essay he wrote for PBS,

Can Quantum Computing Reveal the True Meaning of Quantum Mechanics?
It starts by sketching the description of Nature in terms of probability amplitudes before it switches to the "interpretations". He mentions three – many worlds, pilot wave theory, and quantum mechanics as discovered by its discoverers, in this very order. Bullšiters about "interpretations" never even agree how many interpretations they consider seriously. They only agree that the only correct one – which serious physicists have used from 1925 – isn't at the top. This negative attitude is the only glue that integrates that "community".

(By the way, "Štatl" is a local name for Czechia's 2nd largest city, Brno. The local dialect, "hantec", is a mixture of Czech, Gypsy, German, Yiddish languages and the local argots. "Štatl" is almost certainly a Yiddish contribution and the word is "the same" as the word in Aaronson's blog name.)

Aaronson's main point is that the most important consequence of having quantum computers – if and when they are built – wouldn't be practical ones (simulation or codebreaking). Instead, the top consequence would be that the quantum computer would be "the most dramatic demonstration imaginable that our world needs to be described by a gigantic amplitude wave". Well, I don't think so.

Wednesday, June 24, 2015 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Greece: complete surrender or full collapse

For two or three days, the world was fed by the news that a Greek proposal has impressed the creditors and the deal was around the corner. We heard those things once again.

Today in the morning, we learned that a part of the creditors rejects the proposal. Which part? It's no secret that the International Monetary Fund finds the proposal unacceptable. Tsipras and his comrades only want to increase the taxation – by adding and increasing various taxes attacking the rich and the corporations – but the IMF knows that this is no recipe for growth. If Greece has any chance to become a growing economy able to repay at least a part of its debt, the policies that are needed are exactly the opposite ones. Reduce the spending, reduce the taxation of those who create jobs, and increase the taxation for those who don't (especially the sales tax that is linked to and therefore discourages consumption).

Also, IMF still thinks that the Greek debt is too high (even after the haircuts) so the creditors should accept a new haircut. They don't want to and they have the holy right not to agree with such things, of course.

Confederate flag has at least the same right to fly as Quran

In Germany and Czechia, among other countries, the sale of the Nazi symbols (and the promotion of these ideas) is regulated by the law and nearly banned. The regime has done terrible things, including the murder of 6 million Jews in a plan that was meant to be the "final solution".

The ideology and the people behind the regime got to power by using the excessive tolerance of the democratic system, its toothlessness, and the ban was introduced as a common-sense preventive measure that arguably decreases the probability that a similarly bad evolution is repeated in the future.

The anthem is at least as good as the U.S. anthem.

Americans have often told me that the ban meant that we, the Central Europeans, don't have any respect for the freedom of expression. A ban like this would never take place in the U.S., I was often told, because it's up to the free Americans to choose what they believe. They are treated as the adults and so on.

Except that a much more innocent symbol, the flag of the Condederate States of America, is in the process of being banned in the U.S. The president claims that it only belongs to the museum. Hillary Clinton says that the symbol has no place in the U.S., not even in the museums. She says so despite the fact that she and her husband were rumored to have been closet fans of the Confederacy.

CMS cooling magnet glitch not serious, detector will run

Two weeks ago, Adam Falkowski propagated the following Twitter rumor:

LHC rumor: serious problems with the CMS magnet. Possibly, little to none useful data from CMS this year.
Fortunately, this proposition seems to be heavily exaggerated fearmongering at this point.