Thursday, January 29, 2015

A job search from 88 years ago

I have just found this letter among a pile of old pictures, and decided to post it. It was written by my grandfather's brother, Teodor, who had just finished law-school and was looking for jobs. This was almost 90 years ago when Teodor was 25. Below is a rough translation of some of it.

The letter
"Beloved Brother,

On January 29th, 1927 I saw all my hard work from highschool and university bear fruit as I took my solemn oath in front of the highest court in Bucharest (curtea de Apel). I felt humbled and grateful to an extent that is impossible to describe in words. My soul was full, and in that solemn day, it seemed that all my blood went to my head and I was prepared to go straight to work and work hard as a lawyer. I felt such happiness! I will forever be grateful to God, and to my beloved parents for their work and sacrifices, which made this noble and exalted mission in life possible.

When I wanted to leave the room in which I have taken the oath, I noticed with profound sadness that my silk scarf was missing. I received it as a gift, and it had felt so very pleasant to wear. The solemnity of the day did not permit that I dwell on this loss for long or attempt a recovery.

In 1927
Now that I had the diploma in hand, I started searching for a place to enter life as a lawyer. It does not surprise me that all my efforts so far have been in vain. In Bucharest, I have been talking to many deputies and legislators. Everything I do turns out to be useless.

I have then been persuaded to travel to Timisoara. Overall, I have met many disagreeable individuals who are very limited in their views of life and of the world, and yet hold positions of power and call each other "doctor". This title is beautiful, but you see something is missing. A title hides ignorance just as well as complicated words hide the lack substance. I searched endlessly as I entered the offices of these insects for some place for myself. It was impossible!

[... He tries obtaining the help of G., whom his father had supported through school, and this fails as well. After studying economics, G. had opened a bank that was guaranteed by my great-grandfather, and by many other people in their village. The bank failed a few years later, and the villagers (including my great-grandfather who died soon after) lost most of what they owned around 1929. Later G. recovered and built a hotel in Bucharest...]

Soon uncle G. started criticizing us. He told me that my brothers and I want too much from life, and that we should have started working sooner and at a lower level instead of going to university. He judged me as if he had raised me or paid in any way for my education when I have seen with my own eyes that neither was the case.

G. has many acquaintances on which he can count on only as long as he has money. Afterwards, they no longer remember him. Even now that he appears to have lost everything, he will likely recover through other unclean schemes. However, I do not believe he will be succeeding in the long term. Even though he first reached his position on my father's money, and we loved him and believed in him, he disparages us, and has never tried to help us in earnest. His attitude will not change with circumstances.

It is hard to write a translation that does justice to the original prose. When I read his letter, I feel some of his personality coming through. When I read my translation, I feel my personality in some of the same words much more than I feel his. While he appears excited about starting life on his own and prepared to work hard,  he also comes across as an idealistic college graduate with a sense of humor who is frustrated by his job search, and by the political situation. He tries to be a force of good in the world, but he is still very young, and quick to judge and condemn. My favorite part of the letter is where he refers to the lawyers/attorney from the various offices where he applies for jobs as insects. I relate to the struggle and sometimes to the feeling that everything is meaningless/useless. I suppose that part is timeless.

The background story

The family around 1920.
My grandfather had four bothers and two sisters. Teodor was the second of four boys. They lived in a small village called Semlacul Mare (close to the border with Serbia) that produced corn and grapes. It must have been very difficult for my great-grandparents to raise four boys so close in age, and send them all to school. There was a strong bond between the four brothers that must have been almost palpable. It therefore seemed natural for them help each other, and to get into mischief together.

A picture of Teodor at about 13 is below. It must have been taken in 1914 - close to the beginning of the first world war. He looks uncertain and afraid. It was not common to have to sit for photographs.

Like most of the family, he had big green eyes and brown hair. My grandfather, Mihai, and my great aunt all had the same eye color, and his eyes are likely to have been the same shade of green. He was also funny, mischievous, and charismatic with a beautiful smile - the kind that lights up the whole face and can temporarily stop hearts from beating.
8th grade

When Teodor left home to go to highschool, he pretended to be Romanian nobility in order to be treated more  respectfully by the host family, and allowed to sleep late. Unexpectedly, his father came to see how he was doing. The mistress of the house where he was paying for room and board told him "Sir, please, do not disturb. The baron is asleep", and it was noon. Apparently, once Teodor heard his father call his name, he was awake and dressed in no time, and his stint playing a baron's first son was over.

Quoted conversation between my great-Grandfather and his eldest son, who was of a quieter nature than Teodor, and also ended up being a lawyer:

Father: "Why can you not be more full of life ... more like Teodor?"
Son: "But, father, Teodor upsets you."
Father: "He upsets me, but I like it!".

Later, my great aunt (who was 13 years younger than him, and became a mathematician) was known to tell him:

"Teodor, please, talk to me and pay attention to me when we are together in public. People do not know that you are my brother, and pity me when they see you keep looking longingly after every pretty woman that passes by. They think, poor girl, she is not beautiful or interesting enough to hold his attention."

He came to her highschool graduation exam, which was a public event. She remembered him exiting the room grasping for air and waving his hat like a fan. She had been a very shy child, and he suddenly felt the need get out of the room when his shy little sister started speaking. They were all so very proud that she passed.

Back of the photo records his birth and death
Last photo
Teodor did find a job as a lawyer in Ploiesti, where Romania's biggest petrol refinery was located. He was assigned to represent the state, which was the highest honor for a lawyer. His best friend and colleague was Salvador Bradeanu, one of the best professors of law from that era, who was certainly not limited in his thoughts or in his understanding of the world. They had both studied law in Paris and remained life-long friends.

This is a short love letter he wrote:

"My wandering, unhappy soul cannot find rest
unless it lies close to your breast,
beloved woman.

To you I surrender my love life forever.
Teodor. 24 December 1933."

He had sent this poem on the back of a picture of himself to his wife on Christmas-eve.  It was eventually returned to us.  In Romania, it was common for women to carry photos of their loved ones close to their breast up to the mid 1990s. When I was in middle school, I had a classmate who used to carry pictures of Michael Jackson close to her heart. Of course, we were silly school children, while he wrote this to a woman close to my current age, and it seemed that he had really loved her. However, ideally, at 36 he should not have been so alone - he should have had a wife and children and found some means for happiness outside work. But then it is foolish to judge so many years later while not knowing him or the circumstances.

I do not know whether the love letter was written before or after he divorced his wife.  Teodor had married a widow, and after marriage they lived in the same house as her former father in law, who had significant political power. Soon, he found out that his wife was having an affair with her ex-father-in-law, and divorced. The divorce was quick since he was a lawyer, and they had no common property or children. But even though they had separated, he continued to care for her and sometimes met her in secret. My grandmother, who had met the lady and the father-in-law and had been very impressed by his automatic-electric gate, which was remotely controlled, believed she was likely forced by circumstances to have the affair. Teodor also came to regret being impulsive and divorcing, and later did not blame her for the affair.

He was murdered in 1937 - ten years after obtaining his degree in law. After finding out that Teodor was dead, his ex-wife seemed devastated and asked his brothers "why did you not tell me?". They did not involve her in the investigation that followed, and eventually gave up the search for justice after being told that they will all die if they continued. The last person to see him alive had been his best friend, Bradeanu, to whom he confessed that he thought he would be killed that night. Bradeanu offered to go home with him, but Teodor told him to think of his wife and child, and to go home to them instead. Later Bradeanu would recount Teodor's last day to my mother, who was a resident doctor in Bucharest.

Teodor had obeyed his solemn oath up to the end and refused to be bribed into losing a trial for which he had the legal proof to win. He was educated to always be fair, to put his country and his work first, and to prefer death to dishonor. It was a period when many bright individuals died for being too brave or too fair or just being at the wrong place in the wrong time. Through death he was spared of witnessing the many tragedies that followed. He was, however, missed by his brothers and sisters for as long as they lived.

Tuesday, January 20, 2015

Stellar Collapse in Semi-classical Gravity

Core-collapse simulation image (Philipp Mösta)

Supernova explosion (artist: Mehau Kulyk)
In the simplest stellar collapse model of classical General Relativity developed by Oppenheimer & Snyder 1939, the collapsing star is idealized as a uniform ball of dust that contracts under the pull of gravity. The dust particles that make up the star are assumed to be classical and thus infinitely small, infinitely light, and interact only gravitationally with other matter. This approximation is not perfect since infinitesimally small particles would be infinitely large in size, and could never be localized within the stellar horizon.  

The inclusion of quantum effects is unavoidable both when determining whether a black hole will form and when understanding the final stages of the stellar collapse. When we include quantum effects (arXiv:1501.04250, submitted to Physical Review D),  some of the assumptions above are lifted. A particle on the surface of the star is no longer localized, but is instead represented by its wavefunction. Every particle now has a finite probability of escaping the gravitational pull of the star. This allows for the possibility that some configurations will not collapse to black holes, but will instead disperse or even form stable new configurations. The smaller the mass of the constituent particles, the more significant the quantum mechanical effects become.

Classical paths with all initial velocities
To simulate the stellar collapse using a path integral formulation, we have to integrate over all possible paths towards and away from the center of the star. This includes classical paths with all initial velocities. In the special case of the dust ball collapse these paths can be computed analytically.  We first derive analytic solutions to all classical paths (space-like, time-like, and light-like) in Schwarzschild (Table I and II in arXiv:1501.04250) and Kruskal coordinates (see Table V and VI).

The evolution of the wavefunction
In Schwarzschild coordinates, we can only study the collapse outside r=2M. The motion of the particle on the surface of the star is analogous to the vertical motion of a ball moving under gravity, which can go from an initial point to a final point directly or reach its highest and then come down or escape. Each of these paths is unique taking a different amount of time to complete.

In Kruskal coordinates,  we can model the behavior of a particle on the surface of the collapsing star up to the physical singularity at r=0.  We find that classical time-like paths are unique. A path between an initial and final point can be either direct or indirect (turns back in space). Thus some particles that initially move away from the star can return and contribute to the collapse. Space-like paths can turn back in time, but cannot turn back in space. They are also no longer unique when the final point lies inside r=2M. Classically, no information can exit the black hole. However, by integrating around the classical paths one might be able to extract information from inside the horizon. We only compute the paths in the Kruskal case, and leave the computation of the wavefunction and full exploration of the quantum collapse to future work.

The minisuperspace approximation
Models that apply quantization procedures to general relativity operate in superspace, where a 4-geometry space is represented as a trajectory within space-like 3-geometries. A minisuperspace is a symmetry reduced space where these trajectories are limited to a finite number of parameters describing the constant t slices. We assume that the radius is the only spatial degree of freedom that is not frozen. Such restrictive approximations make the problem tractable analytically. Most physicists reading this have likely worked in minisuperspace unknowingly.

The wavefunction of a particle on the surface of the collapsing star

WKB & Schrödinger comparison
t=5 M, multiple masses
The initial wavefunction is taken to be a Gaussian centered far away from r=2M.  In Schwarzschild coordinates, we then compute closed form solutions to the propagator in the WKB approximation where an expansion is performed around the classical paths and in the Schrödinger approximation, and compare the resulting wavefunctions. We find that the two solutions converge towards each other at intermediate times. They are out of step at early and late times with the Schrödinger solution being more exact at early times, and the WKB approximation being more accurate at late times. For lower particle mass, the star resists collapse longer and the probability that it disperses increases. Further work is needed (including the addition of higher order corrections to the Schrödinger solution) to determine the mass limit at which stellar configurations no longer collapse.
M=0, dotted (WKB), solid (Schrödinger)

In the limit when the mass of the star is zero, the WKB approximation converges to the Schrödinger solution at all times. This checks that the WKB approximation is accurate. The Wheeler-DeWitt equation converges to Schrödinger equation in this limit making the Schrödinger solution the exact solution of the free particle problem (Redmount and Suen 1992). Note that Redmount and Suen did not find a good agreement between their WKB approximation and the exact Schrödinger solution due to numerical issues.
Black holes, black stars or boson stars?
The dust ball collapse is a testbed for relativistic corrections to the Schrödinger equation. Recent work by Dvali and Gomez argue that black holes are a collection of Bose-Einstein condensates. Quantum effects are very important in this situation, and could add potentially new semi-classical corrections that can be investigated.

Other authors argue that there are no black holes and that nature has black stars or boson stars instead. Neither have an event horizon. 

Classical boson stars are formed from dark matter particles that are spin zero bosons and Bose-condense creating a macroscopic quantum object that depending on the particle size can either fit in your pocket or be the size of a galaxy. Since no spin zero particles have been discovered other than the perhaps the Higgs boson, it is difficult to predict which theory is correct. Supermassive boson stars could lie in the centers of galaxies. Upcoming instruments sensitive to light may detect supermassive boson stars through lensing (e.g., see Boson stars as Gravitational lenses and Method for detecting a boson star at Sgr A* through gravitational lensing). In the future, it may also be possible to detect gravitational waves from a pair of co-orbiting boson stars. Additionally, detectors beyond LISA may see gravitational waves from perturbed supermassive boson stars, which would have quasinormal modes that damp slower than if the object had been a black hole.

Macroscopic dark matter particles?
Feeding on dark matter?
Dark matter particles come close to the attributes of classical dust. If somehow black holes can feed on dark matter particles,  the paucity of super-massive black holes immediately above a certain mass M could be linked to the presence of an ultra-light particle halos that black holes heavier than M can feed on. Black holes lighter than M would be unable to capture such dark matter particles in the same way mini black holes produced at the LHC cannot be grown on atomic matter and pose no danger to the Earth. As soon as a black hole reaches mass M, it starts feeding on dark matter and grows rapidly, perhaps swallowing the entire halo. It is important to note that unlike virialized dust halos or stars, the super-fluid dark matter particles would have negligible momentum and thus accrete easily.

Why should we care about black holes?
Supermassive black hole. Artist conception.
In order to understand the universe, we have to understand black holes. They are the most permanent objects in our universe. All life revolves around them. Every galaxy has a black hole at its center. In the early universe, black holes acted as the seeds around which material collected, and eventually galaxies as complex as our own formed.  Black holes are also believed to be the only objects that will be left in the very far future as our universe continues to expand growing cold and empty. They do evaporate, but the evaporation of black holes that are stellar mass or higher happens on timescales longer than the age of the universe and thus is not observable. To truly understand black holes we have to understand their quantum nature, which is not only important in understanding the final stages of stellar collapse, but also in understanding whether they will form at all. The lighter the constituent particles, the more important the quantum mechanical effects become.

This post is based on arXiv:1501.04250, which is work done in collaboration with Prof. Jayashree Balakrishna (Harris Stowe State U.) and Dr. Christine Corbett-Moran (Caltech), and has been submitted to Physical Review D.

This is the first article I have written where all the authors are women. It is also coincidentally my most technical article to date. Note that my co-authors and I do not discriminate and believe in equal rights for everyone. Our collaboration just happens to be 100% female this time.

Tuesday, January 13, 2015

Should clothes define us?

My answer to this question is a strong "No!". I like to wear pretty clothes, but I think that I am the one with the personality and not my shirt or skirt.

When I was growing up, my shirts did not have slogans on them. They generally had one color and were made of cotton. Sometimes they did have flowers or lines drawn on them or some other equally non-defining drawing.  However, as small children, my brother and I did receive compliments of the kind "you are smart like your father, and handsome/pretty like your mother".  Our natural response to this was "No! no! I am smart like my mother". We did not care about looking pretty/beautiful/handsome at the time.

My mom & Mihai
My mom and dad
While both my parents are very intelligent and were good looking, my mother had always been the practical one. And, no, not in terms of fixing things around the house (my father did that and he was very much the man in the house), but in the overall picture my mom was the one who hired people and got things done.    She had been not only exceedingly smart and very beautiful, but also generous and with a talent in interacting with people of all ages. She was an outstanding doctor (my father was a doctor, too, but in the military; my mom was a gynecologist). She had the ability to fix people from all walks of life with very few resources. Whenever we had visits from neighbors, family, friends or strangers, they would all tell her their health problems, and unless they had lung cancer or something equally terminal, she managed to help them get well. She also loved us very much and has always supported us unconditionally.

 Most women I know are both strong and talented. However, our culture does define men and women differently and this is reflected in the writing on the clothes in the stores and in the popular Hollywood movies. Yes, we are different, and we want the men in our lives to be kind to us, but we are neither stupid nor incompetent, and do not like to be insulted and treated as such. This latter fact should not be difficult to understand, and yet when I mention I graduated from Cornell, most people assume I cheated in some way. They make statements of the form "I know many men who are way smarter than you, and did not achieve half of the things you did" and assume that people do me favors. Such beliefs seem to be ingrained at a fundamental level and cannot be uprooted at 20+ or 30+ years of age.
Men's T-shirt

Label: "Women's geek shirt"
I started writing this post after reading an article about sexist clothes and their impact on young children and particularly on girls, which said that the paucity of women in science is related to how we dress girls. It is hard to disagree.

 A simple google on "rocket scientist shirt" shows the two images I included here and a few others. All are very ugly. The one for women here has the crazy old man scientist stereotype and the label "women's geek shirt", which implies that women who are interested in rockets and wear this shirt are geeks.  The one for men is worse, and so I will simply abstain from comments on that.  It cannot be so hard to design some shirts that promote learning, and are decent looking.

Mihai and me at the beach. Hint: I am standing.
Personally, I still prefer clothes that are simple and beautiful without silly statements on them. I am raising boys at the moment, and I would not buy them shirts with "Be a hero", "Training to be Batman", etc. I don't want them to be someone else. I want them to be happy being themselves on all days other than perhaps Halloween.

Conclusion: In principle, clothes should either (1) hold messages that encourage children towards learning something (e.g., math, science, music, art) and increase self-esteem & creativity,  (2) contain some message that is generally positive or (3) simply be cute with no message at all. I generally vote for (3) in the clothes I buy, but that is a personal preference. Anything that is sexist or demeaning should just not be manufactured, and especially not for children who have no say in what they wear.

Note: Thanks to Ruth for pointing out that math & science are not the only subjects that are important ...  I tend to forget that.

Sunday, January 4, 2015

Belated end of year summary

2014 was beautiful and hard in its own way.  It was a good year.  See pictures below. David is in second grade. He has been going to a new school. The move has been quite stressful, but he is starting to like it now. Edward is 4 and not yet allowed to go to kindergarten because he was born after July 31st, and the law in Switzerland is quite strict in that respect. I also live close to work now, which is quite convenient, and close to the veterinary hospital, which has been fun. We have watched the autopsy of a sheep, and how they put all its organs in bags with liquid nitrogen. Cows that come here are often very thin and have IV lines with fluids. We've seen the ambulance for animals and were disappointed that it does not make loud sounds.

Edward and David are both growing and I learn about as many things from them as they learn from me. 
The sheep
David and a goat
Me: “Why do I have to ask you and David so many times before you do something I ask?”
Edward: “Because you don’t always understand us.”
Me: "Just like you do not understand me...but you have to try a little harder. I will try, too".

Just now:
Me: “Are you going to continue to have temper tantrums?”
Edward: “I am not sure yet. You will have to see.”

They often stand up for each other and do most things together. When David was not allowed to board the plane to Israel because his passport was valid for another five months instead of six, Edward chose to stay home, too. I am proud of how reasonable both of them were. 
In Fallanden

Above the parliament in Neuchatel
We have been walking through parks, meadows and forests, and when on vacation on beaches. The children have had extended conversations with swans, ducks, goats, frogs and tad poles. In and around Zurich we have visited various museums, gardens, the zoo and parks with family and friends whom we hope will come again. We’ve watched baby turtles hatch in Greece, seen the Swiss parliament meeting room in Neuchatel (it’s in a castle), and grown quite attached to three sheep in Romania, and to a little dog. 

Presenting our work

in the conference room
Mihai and I have discussed volcanoes, general relativity & atomic clocks at the ICNFP conference under a picture of Jesus and the Orthodox patriarch. The meeting was organised with the help of the Orthodox Academy. 

I finished my first set of job applications for professor positions.  I’ve applied to about 20 positions world-wide.  I have done the first set of seminars and interviews in Israel over the Christmas period. There should be more in 2015.

Tree climbing in the park
With a swan and duck close by
On a cliff
Overall, I am extremely thankful for my family and for the rest of the people and things in my life. My mother told me that she is efficient in everything she does because in her life she has had a lot of practice in controlling her own feelings and emotions, and that in order to take charge of difficult situation one has to first control their own fears and then have the common sense to take the steps that solve the problem. As a doctor of humans she has had plenty of practice with difficult situations where lives were in balance. As a doctor of stars, planets and clocks, it is still often hard to take decisions. It’s also hard to move, and hard to never be certain where I will be next. The search for jobs in previously unknown countries has its own challenges, and I sometimes want to drop everything and run somewhere far away, but I will stick to what I do a bit longer and see what comes out. After all new experiences lead to personal growth. 
On roller-blades
Learning how to fly a hellicopter
Edward at the Petting Zoo

Kite flying

Baby frogs

Changing tires with uncle Mihai

Xmas tree with handmade decorations


Trying to get carnivorous plants to close

Our former house in Fallanden

Thursday, January 1, 2015

Living in Ashkelon

Ashkelon is a little city in Israel just off the Mediterranean coast where we had rented an apartment. It lies some 10 km from the Gaza border. It is cheap to park your yacht there and so, people who own yachts stop in Ashkelon, and then spend their time traveling through Israel.

Mihai being cold
The giraffe cannot keep its head up
In the direction of the Gaza border, there are two towers that look like nuclear power plants, but they are actually coal based with a cooling system that uses sea water.

Ashkelon has ruins from the neolithic period, which contain the remains from many fire-places but only one wall. This we took to mean that the weather was always so nice that people did not need to build houses back then.

Since buried objects last so long in Israel, we were tempted to bury something to test how we find it on return. We decided against it since it is an area where people sometimes worry about bombs, and we did not want to look suspect by burying random jars into the ground. Burying stuff at night made me think of Tom Sawyer & Huck with warts carrying a dead cat - only they were not 30+ years old in the story. There is also Bridget Jones' diaries, but there she has a Mr. Darcy-extremely capable and good looking guy - to get her out of trouble, and we had had enough trouble already.

Beyond offices of interesting people, I saw Israel's various highways and parking lots. The highways were well built. The country felt like California with Deutsche-Bahn trains. All trains in Israel were made in Germany - they even had the same color as in Germany and the architecture of the train stations was similar as well. 

Ashkelon parking lot
Some of the parking lots had interesting topology. One was below sea level and had water in it. Another had similar uneven ground, and was on a hill. It was fun to see how people drive their cars and park with a lot less care than in other parts of the world. My theory is that because the army is mandatory in Israel for both men and women, they get used to driving tanks and flying planes. So, when they have a personal car, they drive it the same way as they drove their tanks. 

There are plenty of stray cats in Israel, and some stray dogs. Along the corridors of the Weizmann Institute there is an array of happy looking cats. I was glad for their company. Some of the cats must have been female and un-spayed and so the female line was not that poorly represented after all.  I was told that people let them come in because the cats are fast enough to catch vipers and other poisonous snakes without being poisoned. Cats are not immune to the venom. Slowing them down by feeding them dry cat food, which retains water and makes them fat, or by tying a bell around their necks like in the US or Western Europe could be cat-lethal in Israel if this story is true. I was glad I did not see any poisonous snakes in my office or any where else I stepped for that matter.