Tuesday, July 24, 2012

Detecting Gravitational Waves in Space?


The LISA Space-Craft. Credit: AEI/Milde Marketing/Exozet.
 Gravitational waves are extremely weak vibrations of the space-time. The fabric of space-time is very stiff. By the time they are close to Earth, the gravitational wave strain for some of the strongest sources is less than 10-20.   These waves travel through the universe at the speed of light and pass unaffected by obstacles. Some are believed to carry information from the beginning of the universe. This post is inspired by the LISA Symposium I attended in May 2012 in Paris. I have waited longer than I should have before writing. So, I cannot give too much detail. I will summarize what I remember from that symposium almost three months after the meeting. The talks are available online if you are looking for more details or for other aspects of the gravitational wave science that were presented and are not mentioned here.



What I learned in Paris
My brother, Mihai, and I
The US side: Since LISA was not selected to fly either in the US or in Europe, there was a call to re-examine the LISA concept from NASA with the aim to develop a concept for a cheaper mission. A series of potential space based gravitational wave detectors emerged. However, most were LISA-like, and all cost estimates were around one billion dollars. They showed it is so far not possible to make a cheaper gravitational wave mission in space.  It did emerge that perhaps there could be multiple LISA-type missions in the future launched by different countries.

The European side: 
Attendants of the Paris meeting. Proof that we were there.

 Even though eLISA/NGO was not selected as the next large European mission, its science was selected unanimously by ESA reviewers as the best among the three proposed large missions. The technology preparation for this mission is going forward with the LISA Pathfinder, which is half a billion Euros enterprise with a planned launch of 2014/2015. So, LISA is not 'dead'. It is going forward with the LISA Pathfinder.  If the Pathfinder is successful, it seems unavoidable that a LISA mission will fly afterwards. The waiting and the preparation process is extremely difficult for any mission. The first LISA-concept was proposed in the 1980s. The Pathfinder will be launched in 2015+ and the mission itself maybe in 2026+. I have only been to one LISA Symposium so far. The enthusiasm built is beautiful to watch, but I also felt some of the pain of the many people who have studied this mission for most of their lives and may not even live long enough to see it fly.

Most space missions take very long to plan and to be launched. This is natural. However, to me as a human it is very difficult to imagine the 2030s. How much of the technology developed now will still be useful then? In 2032 I will be 60.  I've turned 30 in September 2012. I cannot imagine myself being that old yet...perhaps I'll look like my mother, but how will the world around me look? will we have quantum computers by then? will that change our way of life entirely?

Other countries
China and India seemed interested to launch the satellite for free, i.e., in exchange for technology on building the launch vehicle. At this point it is unclear if a future LISA will fly from Russia, the US, China, or India. China has some LISA-type research going on. They plan a pathfinder that will fly in a low orbit to measure the geoid of the Earth. The geoid is called the true figure of the Earth - it the equipotential surface at sea level.  A LISA-type mission will not be in a low orbit and so their naming scheme is confusing. However, the European pathfinder contains an accelerometer that is several orders of magnitude more precise than the 'state of art' accelerometers used in geophysics and, if flown in a low orbit, could potentially measure the geoid. A more accurate geoid measurement will help us map Earth's sub-structure, i.e., find water, oil reservoirs, predict  Earthquakes, etc, and so flying such a satellite would be of high impact.

What about Earth-based detectors? Pulsar Timing?
Scientists have built several gravitational wave detectors on Earth: two LIGO detectors in the US and VIRGO in Italy. They were operational until last year, and they are currently being upgraded. We had an updates from the LIGO and VIRGO teams, and it seemed that the design sensitivity is expected to be reached later ~ 2018 and that they expect a few sources per year. Other detectors are being planned in India, Japan and Australia, but there was not much discussion about that.

Pulsars are also natural gravitational wave detectors. If a gravitational wave passes between a pulsar and the Earth, it will affect the timing between pulses. However, it is important to remember that Ground based, space based and pulsar timing gravitational wave detectors are all sensitive to different parts of the frequency spectrum, which makes these three different techniques complementary and not in competition with each other.

Why build a detector in space?
When a gravitational wave passes by a detector, it compresses and expands the space around the detector by very tiny amounts. On Earth, the compression and expansion measurements are contaminated by deep noise due to the activities going on around the detector, e.g., people cutting trees nearby, traffic, Earthquakes. This noise is very difficult to remove from the data, but scientists have made significant progress in that direction in previous LIGO and VIRGO runs.  However, no gravitational wave have been found to date. The data from the Earth-based detectors is not public in order to avoid false claims of detection and loss of credibility.

On the other hand, space is a quiet environment. However, building a detector in space is much more difficult than building one on Earth. It has to work perfectly from the beginning.  Once it has flown it is very expensive to impossible to fly up there to fix it or make adjustments. So, scientists chose to build the Earth-based detectors first. The hope in the gravitational wave community is that the space based gravitational wave detectors will be built and will fly in the next three decades. We expect to detect many gravitational waves with both Earth-based and space based detectors that will open new windows to the universe, and we hope to hear some of the many untold parts of its history.

Tuesday, July 10, 2012

Visiting Stockholm in the Kingdom of Sweden

The Golden Room in The City Hall
In the first week of July,  I went to the 13th Marcel Grossman meeting in Stockholm. I presented a short seminar on the "Physics of the Far Future" and I will have to submit a conference proceeding about it by February. Initially, I wanted to go alone, but in the end I decided to take the children and my mother. Of course, Mihai and Andy came to attend the meeting. So, everyone was there and we had a reasonably good time. Traveling is a nice way to learn new things, but somehow I always feel relieved and happy to be back home and for the next two years home is in Switzerland.

First impression of Stockholm 
The Blue Room
Stockholm in July is warm and very beautiful. The Kingdom of Sweden is a rocky country with many lakes, and trees, and lovely parks. The average height in Sweden in 1.82 meters for men. I am 1.78 meters and female and Sweden is the only country I have visited where I did not feel too tall. We visited the Skansen museum, the Stockholm's City Hall, the university where the meeting was, and some parks around the hotel. Skansen is a famous Swedish open air museum with a nice zoo and many traditional old houses, which give a glimpse of Sweden before electricity and industrialization.

The City Hall
The Nobel Prize ceremony is held in the Blue Room of the City Hall in December every year. This is where the reception for our conference was held as well. The room is not blue. The architect changed his mind when he saw the beautiful red brick walls of the Blue Hall and decided against painting them blue. After the reception, we visited the Golden Hall (see picture), which is another room in this beautiful building. The golden part of the name comes from the 18 million pieces of gold mosaic and glass covering its walls.  The mosaic figures on the walls looked like the painted walls in cathedrals to me. However, they do not have much to do with religion. They represent important events in Sweden and in the world.

Familiar with dynamite?
On our way to the meeting we were told that we have two minutes to pass on fairly long stretch of road before 'the blast'. We hurried and made it in the two minutes, and than we heard THE BOOM. There was a siren that was announcing the blast as well. It turns out that dynamite is used frequently in Sweden due to the rocky nature of the soil, and we just happened to be along when they had to blow up something. This placidity toward dynamite shocked me a little, which shows I am not of Swedish ancestry. It shocked Andy, too, and he is a quarter Swedish.
An old bike at the Skansen Museum
The Reindeer

The Big Cats and their litter
The snake - this fake animal is what the kids loved most


Sleeping upright?
I learned that beds were really short in the 18th century because people would sleep sitting up tied with some kind of leather belts; they did have some pillows to lean on.  Retrospectively, while it still is surprising, it makes some sense. The reason for this apparent self-imposed torture is that they were afraid of dying in their sleep. It is strange that I have never seen this type of sleeping in a movie yet; in fact I have never heard of humans sleeping in upright or sitting positions all the time and out of choice before this visit to the Skansen museum. It seems that due to the various diseases for which there was little medicine, it was easier to breathe sitting or standing than lying down, which is true if one's lungs are filled with fluid. My 0th order guess is that people must have felt more comfortable this way when they were sick, and that they were sick for so long that they became used to this sleeping position.

Conclusion: in the light of the habits of our ancestors, planes, buses and trains are a natural places to sleep. Oh... and one could say the same about lecture halls and meeting rooms, which explains a lot.

The Discovery of the Higgs announced on the 4th of July
Peter Higgs was invited to CERN after the discovery of the Higgs boson was officially announced. The Higgs boson gives mass to all other particles when it interacts with them, and is a crucial pillar of the Standard Model, which describes electromagnetic, weak and strong nuclear interactions among subatomic particles. Note that even though most people think only of Peter Higgs when they mention the Higgs boson and the Higgs mechanism, the seminal papers of 1964 that described how particles could acquire mass were written by six people: Robert Brout and Fran├žois Englert, Peter Higgs, and Gerald Guralnik, C. Richard Hagen, and Tom Kibble; Higgs was the only one who was the sole author on his paper and had the name that became associated with this new particle. These six scientists received the Sakurai Prize in 2010, and some of them will receive the Nobel prize in the next few years once it is confirmed that this particle is truly the Higgs boson. 

Some of the first seminars about the Higgs boson were at the Marcel Grossman meeting.  The mass of this new particle is about 125-127 GeV (133 times the mass of the proton). The two experiments at CERN: ATLAS and CMS reported slightly different masses with CMS announcing a mass of 125.3 ± 0.6 GeV and ATLAS a mass of ~ 126.5 GeV both with a 5 sigma significance. The corresponding percentage for 5 sigma is 99.9994, which means that pure statistical fluctuations will give a result in the 5-sigma range 0.0006 percent of the time. So, scientists are sure they have found a new particle, but there are still 10+ years of work ahead of the Large Hadron Colider at CERN. They will continue to study the Higgs and its channels of interactions over the next few years to understand which version of the Standard Model is true. A Higgs found with this mass does not rule out supersymmetry. The hope is that the Higgs is not part of a "vanilla Standard Model" and that exciting new physics is very near.

Monday, July 2, 2012

Two Weeks in Romania

This was my first visit to Romania in four years. It was fun to be back! I saw some of the places I had loved, spent some time with my father and spent more time with Edward and David. However, four years is a long time to be away ... too long.

Old Diary
I found my dairy from when I was 12 in my grandparents' house. It only has a few pages. I must have not liked writing too much at the time, but it is interesting to read now.  It has many "exact" facts. For some events I wrote the exact hour and minute, but I did not write the day, month or year. I also liked drama and so I wrote about a big storm and the 1989 revolution and not much about my every day life and thoughts, which I would have found interesting now. The facts trend can still be seen in my writing today. It's difficult to write about real people and feelings without offending and I still avoid writing that is too personal.

Excerpt from my 1994 diary
"It was 6:05 in the evening when Mihai reached the train station in Timisoara. Mother was waiting for him. In five more minutes a terrible storm started. It was suddenly pitch black. The wind started blowing so hard that the big trees on the streets were falling to the ground. Any birds caught in flight were thrown down and hit the asphalt. The rain was very heavy. Water reached 1.9 meters on some roads in less than an hour. Under the bridge on which the railway passes, the cars were completely under water. The submerged cars created an alley on which people could step.

Mother and Mihai reached home safely. The next morning mother had to go to the hospital for work. Mother is a doctor and so it is very important that she reaches the hospital. She had to swim part of the way or to jump from tree to tree just like Tarzan. Up to now, it was reported that three people were found drowned and 26 were injured and taken to the County Hospital. During the storm the town leaders left for safer places, but have returned since and the government is evaluating the loses.

I have concluded that it is most important to be healthy, and I am very thankful that mother and Mihai made it out of this storm safely. Grandfather passed away this year. His death was the saddest thing that has happened to me so far.  He must have asked God to let him watch over mother and Mihai during the storm, and continues to watch over all of us. However, I also think that the watching over family on Earth cannot be all he does and that he must very busy up there with things that we cannot understand."
Ruxandra (at 11-12 years of age)

Recovered "Work of Art" (nowadays everything can be called art)
The 'work of art' on the left is from that period. It is proof that I was terrible at drawing and I still am.  It is meant to show a young princess with a crown among flowers, green grass and trees. The blue balloon-like things must have been UFOs. My brother was fascinated by UFOs, extraterrestrial beings and the paranormal in that period, and would read tons of books in these areas. Such books seemed boring, arid and technical to me. The facts/stories presented, which were too poorly understood for the claims made, never seemed worth the effort of reading the books. Retrospectively, these topics are a natural inclination for a boy entering his teenage years with a vivid imagination and an interest in science. Mihai had read all of Jules Verne's books that were available to us (over a dozen) long before he entered high school. However, he was not interested in the more modern science fiction books like most of my current colleagues because they did not have much connection with reality. Instead he transitioned from Jules Verne to reading about UFOs and  paranormal in potentially real lives, and later on to real science.
How did it feel to be back?
In many ways it feels as if I had never left. When I visited before, I was in graduate school and my grandmother and great aunt had recently died. The house felt empty and full of shadows of a past with more people and more laughter in it.  In addition to feeling sad, I wanted badly to go back to a time when my life had less work and 'busyness' in it and was fuller of people I love and miss dearly, but I knew I could not go back and felt I could not go forward in the less busy direction - at least not yet.  To continue the busyness while at home, I helped former classmates and children of family friends with college and graduate school applications for US schools. However, there was still a strong feeling that while I was very busy, my life was very empty.

(Note that I am a physicist and I do know it is impossible to go back in time. Going back in time implies traveling faster than light and that violates the founding principle of Einstein's Theory of Relativity.)

Now, with the children here, it's all joyful again and it feels so right to be back. The children are happy to have a private back yard and other children of similar age with whom they can run around the block.  There are a bunch of stray cats whom we have been feeding over the past few weeks, and we have a tenant who has a very friendly dog and several friendly neighbors who love children and know how to behave around them. Edward saw chickens, rabbits, a goat, and a horse in addition to dogs and cats.  He enjoyed feeding our cats and playing with the various toys bought for David and his brother Danny, which are new to him and kept him occupied in the evenings or when it was too warm to be outside. I still spent some time helping a neighbor with her highschool graduation exam in Chemistry. She passed the exam, and helping her prepare for it took way less than helping someone prepare 20+ college applications.

My father
My father looks the same as I remember him. He is just a bit older with whiter hair and a whiter beard. He is less interested in life than he used to be, which could be a sign that life is slowly slipping away from him, but he still comes across as a very stubborn person with a strong personality.  He spends too much time watching TV. However, he is taking care of the garden, of Puppy, a former stray dog that my sister-in law brought home when David was younger, and he also partially manages a house we are renting. He does not seem to see or feel an imminent end to his life and I hope this means he still has at least a few more years to live. One thing that surprised me when I returned to Romania this time is how much Mihai behaves like my father did when I was little - in some of the pleasant and of the less pleasant ways. It's sometimes feels so much like going back in time that it is scary. I guess genetics is very important after all, and it is difficult to impossible to stray too much from one's roots. Somehow with all this travel and education obtained all over the world we move forward while being still tied to the past and to our family through parts of ourselves more than through other people and material things.

More of the past two weeks
Edward went swimming for the first time! He also got his first fancy haircut. It was really more of an adjustment; he was not too patient, but our hairdresser was able to cut the uneven parts off his hair; David, my mom and I also have new hairdos. I have short hair now, which fits the really hot weather.  Oh...and  I was told I still look 16 by our next door neighbor. It felt good to hear I don't look as if I am 100 - I am turning 30 in September. The compliment may be related to the fact that I have been wearing some my clothes from before I left home. Some still fit, but not all.

My mother, Tusa Tavi and me in 1983
On Sunday we visited the house in Lugoj where my grandparents had lived. It is a lovely Victorian home with high ceilings. The yard is overgrown with weeds at the moment. It used to be full of beautiful flowers that seemed to only get bigger and lovelier as the years passed (see picture below; my mom was about 6 years older than I am now).

The children had fun sitting on the porch, which is still cool even in really hot summer days, and Mihai changed some broken shingles in the attic.  The roof is leaking in one of the rooms. I hope we will be able to fix it before the fall comes. The house has been empty since my grandmother and great aunt passed away, and I still have a feeling of time stopped in place every time I go there. It is still full of old things that my grandparents had or that Mihai and I used as children.

How long have I been away and where is "home" now?
At the end of July I am entering the 12th year since I left Romania to go to college in the US. In all this time 'Planet Earth' has been my true home and the target of my various jobs/job applications. I live in Switzerland now, but I still feel home in Romania in so many ways that are difficult to explain and I am considering returning to Romania in the future.

My family lived in Timisoara from when I was 6 until I left home at 18. While growing up, my brother and I had spent all vacations with my grandparents in Lugoj, a small, quiet city about 60 kilometers from Timisoara.

Why the four year gap between my visits to Romania?
 Where was I in the past four years?  I was a postdoctoral scholar in the US at Pennsylvania State University from 2008 until October 2011 when I moved to Zurich. The Penn State astrophysics and physics programs and the scientists there are pretty amazing. I loved Penn State just as I had loved Cornell as a graduate student, and the University of Illinois in Urbana-Champaign as an undergraduate. I highly recommend all three schools.  In addition to the brilliant local faculty, we had many external speakers whom we were encouraged to meet and significant freedom to travel and work on projects of our choosing, which is partly why the topics of my research are so varied. The other reason for my all-over-the-place-research is my personality. I find it difficult to work on one project at a time.

After I moved to Zurich, it took some time to find a house, to get accommodated, etc and the 2011 year passed very quickly.

Why so difficult to travel from the US to Romania?
As a student I did not have problems, but the work visas are so much more painful to obtain and extend. On an H-1 visa somehow the number I entered the country on was used to pay me and exiting on an existent visa meant invalidating any future-already approved visas.   Oh...and I had to change visas every year and re-apply 6 months before changing it. My last H-1 visa required significant work on the part of my postdoc advisor and the secretaries to prove to US immigration that I was not qualified and could receive the minimum payment allowed by this visa. Nobody can do much to improve the situation at this point because immigration is so unpopular in the declining US economy.

My parents have visitor visas for the US. My father did come to visit me once in the fall of 2010 and my mom came twice over this four year period. However, my father has a heart condition and such long trips are very tiring for him. So, the distance itself is a problem and I am glad to be on the same continent now.

In Switzerland, there are work permits just like in the US, which need to be renewed every year for the first two years, and then I perhaps can receive a longer permit.  However, these forms have no connection to how many times I exit the country. So, I can go to professional meetings outside Switzerland and visit my father as well; and, of course, I can also travel for fun.

How was the trip from Zurich, Switzerland to Timisoara, Romania and back?
Long and tiring. There is no direct flight from Zurich to Timisoara. On the way there: Edward (1 year and 10 months at this point) and I took a train to Milano Centrale (about 5 hours total) through Bern. Then we took a bus from Milano Centrale to Bergamo. Afterwards I took a cab to the nearest hotel, and another cab to the airport the next morning, and then a flight to Timisoara at 7 a.m.  The way back was all in one day leaving Timisoara at 6:00 A.M., reaching Bergamo at 7 A.M., and then taking a bus and several trains and other buses. In general, there is a direct train from Milano to Zurich, but there was a rockfall and land slide on the way and a bus goes around that. Slow, regional trains have to be boarded afterwards. So, after leaving our house in Timisoara at 3:30 AM (we did not sleep at all that night), we reached Zurich at 4 PM. Going through all this with two small children was not fun.

We went to Romania again at the middle of August and left in September. My mother and I drove this time.  It took two days each way, and it was an equally long and tiring trip. The first day the children were OK, but the second day seemed just too much for them. Perhaps I will try taking the train next time.