Sunday, November 23, 2014

The next best president?

Four US presidents at Mount Rushmore
After hearing our discussion on Obama's immigration reform, my nephew, David exclaimed "Obama must be a really good US president, but I am sure you would be a better one!".  Children really know how to compliment me.  However, David later took some part off the compliment by saying that Mihai and Andy will be even better presidents because they are smarter than me. He had thought of me first, though, which shows my importance as his hero. Of course, I am not a US citizen and thus not allowed to ever candidate. So, nobody will create a statue in the mountains for me. However, hearing such estimates is good for my self esteem - especially in the job application season when my self-esteem suffers dreadfully.

I, too, remember being 7 in 1989 when the question of electing a new president arose in Romania, and seriously thinking who in my family will be the better president after the revolution. I think both my parents came high in my estimates at the time. I don't remember how I placed my grandparents or great aunt, but I know my mom came first.

Obviously, when my parents were so awesome, I had no reason to seriously consider a stranger....well... at least not until we really had to vote. My grandparents were allowed to vote from home for the first free election after 1989. I still remember barely reaching the table to read the voting bulletin with my grandfather. He, my grandmother, and my great aunt were at the big table in the living room with the person gathering the votes, while Mihai and I were circling the table in our endeavor to help everyone and felt important and useful.  Unfortunately, they forgot to allow them to vote for the second round of the elections when it mattered more. I remember we waited and waited, and were really disappointed when nobody came. The votes were counted suspiciously, and I felt betrayed when Ion Iliescu, a former communist, won the elections that year. However, the borders opened and we had freedom of speech. There was an old man in a village that my mom drove through who was very sad and told us it was sin against God for a person who had been in charge of a concentration camp to be president (he remembered a young Iliescu in a fancy suit who came to his village to take the best and brightest young men to the Danube-Black Sea channel; most did not return.)  Iliescu won the presidency a few more times after that. I was a physics PhD student at Cornell when he finished his last presidential mandate in 2004. I voted for the first time in 2014 and this time it seemed that votes mattered. Romania has the first president who might reduce corruption, and build a more transparent bureaucratic system starting from the top.

Neither my parents nor I have an influence in politics, and I hope any children I raise will stay away from that field as well. It's too hard to be a politician and be honest, and loved by everyone. However, it's important to always keep enough strength to dream, and the dreams of children are the most beautiful of all.

Friday, November 21, 2014

Under the Feet of Giants

Other movies by Kip - When I was a student, I used to watch movies with Kip. They were made by my brother, and did not feature famous actors. Instead they recorded lectures on gravitational waves.  Kip was primary actor and executive producer, and Mihai, a Caltech graduate student at the time, was "the driving force behind" (see Kip's course description). These lectures are still being watched by people around the world.

Today web courses are not a novelty. However, in 2002 the internet was too slow for them, and the cameras used for recording seminars were of very low quality. Mihai wanted his movies to be good enough to be watched for many years to come. He convinced Kip that they needed closer to Hollywood-quality equipment than Caltech could provide. Since their outreach department did not have the grant money to help, Mihai bought the equipment, taught himself to use it, and burned the movies on DVDs, which took many, many nights and days. He was, of course, reimbursed from Kip's grant, and was paid a regular Caltech graduate student stipend. Kip himself spent significant time organizing the course, giving the lectures, and inviting some of the experts in the field to be guest lecturers.  In addition, Yanbei (another graduate student who is now professor at Caltech and leads the TAPIR group) and Mihai had regular teaching assistant duties. Mihai also had his Caltech qualifier exams that year, and took classes himself.

I am three years younger than my brother, and we had always been close. In 2002, I was an undergraduate at the University of Illinois working in Ed Seidel's group. Every time I visited Mihai, he would take me to Kip's group meetings, and I would sometimes help him burn DVDs at night. Once I finished my undergraduate studies, I was admitted to both Caltech and Cornell, and to other universities as well. I chose Cornell.  I knew Kip reasonably well by this time from my Caltech visits, and I also sometimes saw him at meetings. He came to the first talk I ever gave, helped me answer my first set of questions, and was, in general, kind to me. We even stayed at the same hotel, and took a taxi together to my first American Physical Society meeting.

Once the gravitational wave web-course by Kip, Mihai and Yanbei, was finished, Mihai personally took DVDs to the Albert Einstein Institute in Germany, and gave seminars about it throughout Europe. We were also invited to Louisiana State University, where we watched and discussed the lectures with a group of students that included Ravi Kopparapu, a brilliant physicist and friend. I later organized gravitational-wave lecture watching at Cornell.

So, what is the connection with Interstellar? The movies Mihai made might have given Kip the idea/confidence to start Interstellar.

The day he met with Steven Spielberg to discuss the acceptance of the script (wrote by Linda Obst and Kip), Kip took an overnight flight to Cornell and told us about his meeting the King of Hollywood.  This was about ten years ago. After briefly discussing with a long line of people who wanted his advice, Kip went to the back of the room to talk to me about my brother's potential graduation from Caltech. My Cornell professors waited in the front of the room, and were very impressed that Kip had found so much to talk about with a mere graduate student.

The rest of the story
By 2006, Mihai was a 5th year graduate student, who was trying to obtain his PhD degree. He had written an article with Kip in Physical Review D, and had done other work as well. I'll never forget my discussion with Kip that day after the script of Interstellar was accepted by Hollywood. Kip told me that he could not possibly let my brother graduate because the article they wrote together amounted to only 5% of a PhD thesis. The other work he could not evaluate because it was not in his field. Mihai had an argument with Kip over the importance of string theory vs. that of gravitational waves. He had stopped working for Kip and instead did some work at the interface between string theory and gravitation. He was the only student ever who had been sole author and has won an award from the Gravity Research Foundation. However, Kip thought that while famous people like Stephen Hawking wrote articles for the Gravity Research Foundation competition and won, the award was not prestigious enough and thus they did not matter. This was unlike awards from the American Astrophysical Society. Since my brother's petition was official, this evaluation was later done in writing as well. As I walked Kip back to his hotel, we concluded on a more personal level where I explained how much my parents, and especially my father, want Mihai to graduate. After all he had already spent 5 years of his life working towards this degree. Kip said he understood the pressure having had two children himself, but that he had to accept the fact that one of his own sons did not graduate from highschool. We parted friends.

I suppose it's true that sometimes parents (and siblings) just have to accept their children's failings. I, of course, agree that Mihai should have never argued with Kip in the first place. However, I can never consider my brother a failure simply because he is not one. He will never be a failure in my eyes, whatever the world thinks. I also pledge to always try to stand by any children I raise, but hope they will not attract as much trouble as my brother always has, and that they will always stand by each other.

Epilogue: Coincidentally, the ending of the Interstellar movie is along the lines of my brother's thoughts. It states that the equations we know now are not enough to understand the world, and makes extra dimensions and string theory play and important role. The original ending was supposed to involve the Laser Interferometer Space Antenna (LISA) mission, which would have been a less speculative way to find the worm-whole.

Mihai did graduate with a Caltech PhD in June 2007. His Caltech visa did not extend to the last year. For international students, this is can be problematic if they exit and want to re-enter the country. So, he obtained a job at the Mitchell Madison Group (MMG), a global consulting firm. This involved working around the clock to restructure major companies in a failing economy. He was promoted to work with the highest ranking partners and paid at about $2 000/day (before taxes). In addition to this, he had found out that emeritus professors can also sign his PhD thesis, and went and talked to every retired professor alive from the area. Each discussion was interesting and yet difficult in its own way. Eventually, he gave a seminar that convinced Barry Barish to be on his committee and sign his PhD.  For this he continued research work with Yanbei Chen that involved optimizing mirrors for advanced gravitational wave detectors. He took a number of transatlantic flights to work with Yanbei. He also married. David was born in February 2007. To be with his wife when David was born, he took paternity leave, and that forfeited his consulting job, but it allowed him to finish his PhD. Before his PhD defense, he was told he will fail if he defends. He chose to defend anyway. He presented his work well, and passed.

Many students who have done less are allowed to graduate because being humble is often valued more than being talented. At the time, it seemed so unfair. Since then I have seen this happen time and time again with many talented people who quit science because they had little or no support from the scientific community. Every time it happens with a person I know well and think highly of, I feel so powerless. We assume loses that we cannot afford, and yet we do it again and again - not caring about the future.

Mihai's salary stipend
After he graduated, Mihai did a one year postdoc with Yanbei, his co-author on the movies and friend. He was paid for the winter months at full salary, and then the AEI continued paying him with 300 Euro/month for the rest of the 2008 year. Mihai slept in a car he bought for 300 Euro. To help prepare Yanbei for his upcoming Caltech professorship, Mihai suggested they organize a journal club where they discuss and try to understand the most recent articles in the field. Since they were both Caltech PhDs, they were well matched and could understand scientific work often only after discussing with each other. They also published their work on optimizing the mirrors of Fabry Perot cavities in Physical Review D, which has been well received by the community. After that one year,  Mihai joined the faculty at the University of Mississippi. He taught Mathematical Methods for PhD students while he was still the youngest in the class and was voted by his students to be the best teacher in the physics department. He was in Mississippi for two years, retained an affiliation with Olemiss to date, and also received a similar position at the Universitatea de Vest from Timisoara.

Mihai has always believed in people and, generally, notices only their good side.  He even claims to have enjoyed sleeping in the car. His marriage broke up about a year later. I have never agreed with the type of sacrifices he made for other people and for his quest of immortality. I try to be a force of good in the world, but never at such expense for my health or my family.

This post states facts as I remember them happen. It is not meant to offend in any way. I have admired and respected Kip Thorne all my life. I still do. So do many, many other people. He is my academic grandfather, and the academic father of some of the best scientists in the world. I also think very highly of Yanbei who leads the TAPIR group at Caltech, and is an outstanding professor in his own right. I consider him to be a friend as does my brother.

Mihai's note on String Theory: Beyond their contribution to science, a lot of String Theorists end up working in the financial and consulting world. The availability of cheap string theory brain for companies like Goldman Sachs, MMG or McKinsey give the US the competitive edge to stay afloat despite its massive debt.

Tuesday, November 18, 2014

Voting in Romania

Voting section
I went to Romania to vote.  I actually wanted to support one of the candidates this time! Thanks to Wizz air (15 Euro/flight up to the last minute) it was easier to fly to Timisoara than to figure out how to vote abroad. Coincidentally, we ended up voting in the physics office of the school that our address was assigned to. There were 3 voting booths, a few people, and no waiting line. I was also impressed that stores did not sell alcohol on Sunday (the voting day) because people were supposed to be clear minded.

So, who won? and what do I think of them? Klaus Johannis (Partidul National Liberal). He is a highschool teacher of physics turned politician, which can be taken as one more proof that physicists are smart and can do anything! His election should make the country more open and more connected to Western Europe. There are already a lot of investors from Italy, France, Switzerland and Germany, which lead most of the agricultural sector and most businesses in Romania.  Mr. Johannis is from the German minority of Romania and speaks Romanian with a slight German accent. I found it a bit funny to be listening to him talk. I could almost envision hearing him speak the German translation of his words.

His opponent had been the current prime minister, Mr. Victor Ponta - Partidul Social Democrat, i.e., the socialists/communists. Even though he is young, he is the typical representative of the current political class. Fortunately, this class no longer has strong roots in part due to the large number of foreign investors. So, I have never thought he would win the elections.  He did lie on his resume, and I found it interesting that he was still allowed to candidate. The argument that he did not plagiate because he hired somebody to write his PhD and did not copy himself was particularly funny. Of course, the official version is that he just misused citations for 75% precent of his thesis. Also, he took one course abroad, and then claimed to have a Masters. All this is reprehensible, but then Vladimir Putin also copied his thesis and so did many, many other corrupt leaders. Nobody calls them Dr. Copy-Paste because they are politically too strong to be picked on that way. Furthermore, Ponta is a bit older than me and almost became president and he must have some strength of personality just to be able to stand all the pressure. So, I do believe he does deserves some respect for that and not just media shaming.

Romania is the one country that makes me feel home whether I visit for a few days, a few weeks or a few hours. I still have faith in it. In the long term, I expect progress to continue, the business and agricultural sectors to thrive and property prices to grow. However, just like in the rest of the world, there will be times when things will get worse and times they will get better again. So, I try not to build unreasonable expectations. Had Ponta won, it would have been nothing out of the ordinary - just a continuation of the same corrupt regime, but now people have hope. I pray that they will not be too disappointed too soon.

Disclaimer: I do not own a TV, and I have not been listening to presidential debates. I did hear both Ponta and Johannis speak for about 10 minutes each after I voted. I suppose that means I am not a well informed person, but somehow the trash throwing that the politicians do never seemed worth my time or peace of mind.  

No Alcohol on voting day
Will I move back to Romania? It's unclear.  So far I have consistently tried to be in the country where I thought I could do the most science. I have spent so much time studying that I thought it a pity to not continue, but I am not sure what I will do in the long term.

I close by quoting my brother: "Life is beautiful when you wake up in the morning and for a few minutes you do not know what country you are in today, and when you do not yet know what country you will be in tomorrow". He lives this way. For my side, however, I have mostly been feeling uncertain and afraid instead of excited and looking forward to many next adventures.

Monday, November 3, 2014

Testing Alternative Theories of Gravity with Atomic Clocks

Modelling the Dark Side of the Universe
Most our instruments are built to detect light (e.g., stars, dust, galaxies), and so we still know very little about the dark sector, which comprises more than 95% of the universe and neither emits nor absorbs light. The simplest type possible type of dark matter particles are those represented by a spin zero scalar fields. Scalar fields can arise from not-yet understood physics such as compactified extra dimensions. The Higgs particle is believed to be the first fundamental scalar field ever detected. In cosmology, the initial rapid inflation of the universe is also best modelled by a scalar field called the inflaton, while the quintessence scalar field generates a form of dark energy that may account for the accelerated rate of expansion of the universe. It is reasonable to believe that similar to the visible sector, the dark sector is rich and contains particles of different kinds with various masses.

Alternative theories of gravity and PPN parameters
The solid line corresponds to 10-16 clock stability. 
Einstein's theory of gravity alone cannot account for dark matter or dark energy. Instead, a scalar field that may couple in different ways to different kinds of matter enters the theory of gravitation in addition to the metric tensor of general relativity. This field couples to matter and therefore violates General Relativity. The standard way to describe deviations from General Relativity in weak gravitational fields is via the Parametrized Post-Newtonian (PPN) formalism. The most commonly constrained PPN parameters are 𝛄 and β.

In Einstein's General Relativity 𝛄=β=1. When the scalar field is massless, the 𝛄 and β parameters are constant. The introduction of a mass term causes the 𝛄-parameter to become distance dependent. It is thus natural to expect that PPN parameters may depend on both the distance from and the composition of the mass they are tested around, e.g.,  their value measured around the Earth would be different than around the Sun. The strongest constraint on the 𝛄 PPN parameter comes from the Cassini spacecraft, which limits the size of the parameter around the Sun to 2.3 x 10-5 (1-sigma confidence level). Null results from planetary ephemerides place similar constraints on the  β parameter.

Testing Alternative theories of Gravity with Clocks in Space
Performing accurate timing experiments with satellites carrying state-of-the-art atomic clocks in Earth orbit can test alternative theories of gravity such as scalar-tensor theories. The Hydrogen Maser placed aboard the International Space Station as part of the Atomic Clock Ensemble in Space (ACES) mission is expected to reach  a frequency inaccuracy of 10-16.  

We calculate the gravitational redshift for an eccentric Earth orbit induced by varying PPN parameters and compare it to the one predicted by GR.  We find that a clock with the stability that should be achieved by the ACES mission placed in an elliptical orbit would constrain 𝛄 and β to the 10-6 level (see figure). We take an eccentric orbit with the same parameters as that proposed for the orbit of the originally proposed STE-QUEST satellite.  Choosing an  eccentric orbit makes the signal stronger since the relativistic effects are larger than for a circular orbit due to the higher velocity at perigee.

PPN parameters for general scalar-tensor theories
We compute the PPN parameters γ and β for general scalar-tensor theories in the Einstein frame, which we compare to the existing PPN formulation in the Jordan frame for alternative theories of gravity. Note that there are infinitely many possible frames, but these two frames are the ones that are typically chosen. In the Einstein frame, the Ricci scalar appears alone and the matter fields couple to a conformally related metric, while in the Jordan frame, the scalar field multiplies the Ricci scalar and any matter fields present couple directly to the frame metric. This computation is important for scalar-tensor theories that are expressed in the Einstein frame, such as chameleon and symmetron theories, which can incorporate hiding mechanisms that predict environment-dependent PPN parameters. 

Extended Point Source?
The PPN parameters are typically calculated for a space-time consisting of a point source surrounded by vacuum, which is not accurate for experiments performed around extended objects like the Sun. Instead, we add a parameter that measures how much the exterior gravitational field deviates from that of a point source with the same mass.  To check our assumptions, we recompute the Cassini constraint modelling the Sun as a homogenous sphere instead of a point source for massive Brans-Dicke theories, and find that the 𝛄-PPN  constraint becomes more stringent.

The article this post is based on was led by PhD student Andreas Schaerer.  The paper is published in Physical Review D. I have also written a conference proceeding that describes tests of gravity with space-based atomic clocks and atom interferometers.