David Waller

Final thoughts

The Quantum Diarists were asked to come up with a "best of" list from the last year of blogging. I've decided that my favourite three blogs were

• Trip to SNO,
• Stay-at-home physicist, and
• No, I don't study snow.

These were my favourites because I feel they do the best job of giving a flavour of what it's like to be a young physicist. My hope is that these blogs have provided an interesting little window into my life. It has been a lot of fun to blog during 2005: the World Year of Physics. I hope it's clear from my blogs that I feel that I am extremely fortunate to spend my days doing something I love and to get paid for it too!

Writing these blogs has been really enjoyable since I love to tell people about what I do. I love to tell them about physics. Granted, not everyone in the world wants to know about physics (data from cocktail parties strongly supports this hypothesis), but if you have come to this blog, I assume you are interested!

I hope those who have read the blog have enjoyed it and have learned a little at the same time.

Signing off, David.

Unwritten blogs

Many, many, many times I have sat in a bus, train, car, etc. in the last year and thought about ideas for blogs. I have averaged about 3 ideas per day. Unfortunately, I have managed to write only about 3 blogs per month (this is a guess - might be 2, might be 4). There are never enough hours in each day. This month has been pretty typical in that regard. As a result, I thought that one of my last blogs for Quantum Diaries should be about blogs I wished I had written. Naturally, this list is pretty biased towards recent ideas (actually, they all come from the last month or so).

Blogs I never wrote but wished I had:

1. Trip to UBC in Vancouver for SNO meeting three weeks ago. Had a really good time. Meeting on SNO's neutral current detectors was excellent! Kudos to the organizers and participants. I love Vancouver - one of my favourite cities in the world.
2. Canadian general election on Jan 23, 2006. I'm not really excited by any of my local candidates. That's not unusual, but it is sad. Come to think of it, none of the major parties or their leaders are overly appealing either. Sad, sad, sad.
3. My first Christmas holiday away from Edmonton (my home town). It was really relaxing to be in Ottawa with just my wife, daughter and mom. I was also nice to have our first Christmas tree. I'm not Christian, but neither are Christmas trees!
4. The most recent remake of King Kong was a very exciting movie. Go see it if you like pure escapism.
5. Post-doctoral researchers at Carleton University don't get to use the athletics facilities without paying out of their own pockets. Embarrasing. I emailed the new university president about it a couple of months ago. It was news to him - hopefully this ridiculous rule is changed. Virtually every other University employee is given free access. This makes post-docs feel like second-class members of the University community. When this crazy rule was created, maybe someone in the adminstration decided that post-docs should be spending more time in the lab and less time in the gym.
6. The SNO post-doc collaborator with whom I do most of my work has just been offered a nice job at a different university. That means he'll be leaving SNO in the very near future. This is bad for SNO since he's made a very big contribution and does lots and lots of work on the software side of things. He's pretty much irreplacable at this point.
7. The Carleton-SNO group has hired a new post-doc. He started just a month ago but has been making good progress. This is good since he's supposed to take over some of my responsibilities (so that I can have more time to do physics analysis!).

I'm sure there are dozens of other ideas I could write down, but I am running out of time (as usual)! I need to check how far apart my wife's contractions are now...

Labour begins

This should be quite an end to the year. My wife has just announced that she has gone into labour (at 90% confidence level for all you physics/stats aficionados out there). The odds are that we will have our second child before 2006 starts.

I should have been more prepared than I currently am... The due date for our child was January 6, 2006. I was told that the one standard deviation uncertainty on a predicted due date is 6 days. Since I use statistics on a day-to-day basis, I knew this meant that there was a 2% chance that the baby could have been born before Christmas Day. Also there was a 16% chance that the baby could be born in 2005.

Despite these non-negligible probabilities, I managed to convince myself that there was "no chance" that the baby would be born before New Year's Eve. Who was I fooling? Myself, obviously. (This is a clear case of Bayesian inference being totally unreliable. ;) )

I suddenly feel very pressed for time. My wife's contractions are about 10 minutes apart so while the birth is not going to happen in the next hour, there is a good chance it will happen in the happen 12 hours.

Now that the possibility has sunk in that I might have only 12 hours left of being a parent of only one child, I think I had better get some sleep right away. It might be my last decent sleep for many months! Sleep?!?! Who am I kidding? Myself. Again.

Trip to Philadelphia

I travelled to Philadelphia a couple of weeks ago to visit with SNO collaborators at the University of Pennsylvania. It was a very quick trip: one night and two full work days. However, it was very productive. I was meeting with two other members of SNO's Hep Neutrino working group who work at Penn. We are nearing the end of our search for rare Hep neutrinos from the Sun (see old post on April 2 for more details on these elusive neutrinos).

The goal of our meeting was to wrap up some loose ends and convince each other that we have done a thorough job on the analysis. I think we were successful on both counts. We tied up all but a very few loose ends, and everyone was happy with each other's work at the end of the two days. We hope to have a paper for internal SNO review early in the New Year. Soon after that, we can submit the paper to a journal.

As I mentioned in an earlier blog, we are also planning to search for neutrinos from ancient supernovae. We don't yet know the results of either of these searches. Only once we are 100% satisfied with every last detail of how we do the analysis will we look at the data. At that point we will arrive at our result very quickly since we won't be changing any details of our analysis.

Those will be nail-biting times when we finally look at the data! If we see a signal for Hep neutrinos or the Diffuse Supernova Neutrino Background, it will be an exciting and unexpected discovery. Even if we don't see anything, we will set the most stringent limits to date on these rare neutrinos.

I had sincerely hoped we would have a final result before the World Year of Physics and this blog are over. Alas, the desire to get a speedy result must defer to the need to get the right result. If we do discover something, maybe you'll read about it elsewhere...

Concert month (revised Dec 19)

November was an usually good month for concerts in Ottawa. I went to three, but could have happily gone to several more.

Concert #1: Kid's Show

The first concert we saw was definitely the most fun. It was our 19 month old's first concert and lucky for her, it was given by her favourite kid's singer: Connie Kaldor. If you have kids and they like music, I strongly recommend her CDs. The lyrics are great and the music is catchy - it's definitely a cut above most kid's music. Zoe has both "A Duck in New York City" and "A Poodle in Paris".

The best part of the show was watching Zoe's reaction to it. She went absolutely bananas dancing. At first it looked like she couldn't believe that the music she knows and loves was coming from a person on a stage instead of a stereo system, but once she got over that she really let loose.  She didn't stop dancing for over 45 minutes. It was exhausting (but hilarious) just watching her. After her favourite song ended, and the applause stopped, she yelled out "Again! Again! Again!" at the top of her lungs so that all the audience could here her. The crowd loved that. There is no-one as uninhibited or joyful as a child. It's sad that we lose that lack of self-consciousness so soon in life: the 7 year-olds in the row in front of us were embarrassed by Zoe's zeal. Sad.   

Concert #2: Sarah Slean

  Sarah Slean is a great Canadian singer/songwriter/musician. Like most female Canadian singers, her name is Sarah (think Sarah Maclachlan, Sarah Harmer, etc.)...

...After more than two weeks, I will try to finish this post (for the third time!). Things have been very busy lately...

...Anyhow, Sarah Slean was fantastic. I try to avoid strong words like "fantastic" since they are usually gross exaggerations. This time however, the moniker is appropriate. Ms. Slean was is sparkling form. Her voice was near perfect and her piano playing was even better than her voice. She played in a nice old church in downtown Ottawa for about 300 blessed souls. Her lyrics are far from virtuous so she made many jokes about being struck down by lightning while playing in such a venue. To make a long story short: if she comes to your town, go see her!

Concert #3: U2 and Arcade Fire

  This concert was the icing on the cake - a perfect way to end a super month of music.  I have been a fan of U2 for over 20 years now. That's a long time. I had never seen them before so I figure I was due.

I was actually even more excited to see the opening act: Arcade Fire. They are from Montreal and they are great. Maybe they will be the next U2... Last year, my Montreal-based-budding-rock-musician cousin gave me their first and only CD for Christmas. I hadn't heard of them at the time but she told me they would be famous. They are now! I love their CD so I was over the moon when I heard they would be opening for U2. I had had the U2 tickets for almost six months before I found out Arcade Fire were the opening act.

Sadly, my dream concert became a nightmare thanks to a travel delay and the most disastrous parking lot known to humanity: the Corel Centre parking lot. Our departure to the concert was delayed by 1/2 hour thanks to our daughter, Zoe, sustaining a split lip right before we were about to leave her at my mother's house.  Rowdy Raffi music, bouncy couches, sharp speaker corners and 19 month-olds are a volatile mixture.

Despite heavy traffic, we managed to get to the Corel Centre at 7:30 when the concert was supposed to start. However, we had not counted on it taking over one hour to park our car. That's right, from the time we were 20 metres from the first lot to the time we parked was over 60 minutes. Whoever designed the parking lot and roads there should be shot.

As a result, I saw a grand total of 30 seconds of the Arcade Fire before they left the stage. Perhaps the most annoying part was that over half the seats were empty during their performance. All the #$#^&%#& people who were in front of me for parking went straight to the hotdog and beer stands and didn't even bother watching the opening act. I was very, very sad. Not a good start to an extremely overpriced evening of entertainment.

Thankfully, U2 surpassed my expectations with their performance. They were truly memorable. I worried they might seem tired and old. Instead they were fresh and captivating. Their old songs and their new songs all sounded good.

All in all it was still an enjoyable evening. Had I seen the Arcade Fire, it would have been a super evening. [sigh] Maybe next time they come to Ottawa I'll get to see them. As long it is not at the Corel Centre...

A tear jerker for nerds

Last night I watched the movie "Contact" on TV. It is the second time I have seen it, but I thoroughly enjoyed watching it again. Jodie Foster plays a radio-astronomer who is a member of SETI (Search for Extra-terrestrial Intelligence). Naturally, she gets lucky and discovers a message from an alien intelligence.

Despite the stereotype about science-geeks loving science-fiction, I usually don't care for science fiction. "Contact" is a stand-out exception though. The original story was written by Carl Sagan, who was a real-life astronomer. Having a real scientist write the story probably helped since it avoids the usual pitfalls of crap sci-fi by having the science part correct and minimal and by focussing on the human aspects of the story.

That said, my favourite part of the movie is when Jodie Foster's character first discovers the radio signals from outer space. She quickly realizes that the radio pulses represent numbers: 2, 3, 5, 7, 11, 13... As soon as her character said "2, 3, 5, 7...". I yelled out, "Primes! Prime numbers! They're prime numbers!!!" I got so excited I forgot for a moment I was watching a movie. My excitement quickly turned very emotional - I felt like crying.

Maybe it's my lack of sleep from being on graveyard shifts at SNO for the last week. Or maybe I'm just a big softie for dramatized scientific discoveries. As if that wasn't bad enough, another scene later in the movie had me tearing up again: Jodie Foster witnesses the early stages in the formation of a solar system. She is overcome by the beauty she sees and suggests that a poet would make a better space explorer than a scientist since a poet would be better at conveying the beauty of the Universe.

There are more "overt" dramatic moments (tragedy, romance) in the movie that I imagine are supposed to elicit emotional responses. Interestingly, they didn't do much for me. For me, they couldn't compete with the movie's portayal of the emotional power of scientific discovery. I guess that's pretty strong evidence that I am in the right line of work.

I have yet to make a big scientific discovery in my career. I hope I can have that good fortune in the future. Until then, I will be happy to live vicariously through the fictional discoveries of imaginary people.

Is a faster electron a heavier electron?

Here's a recent question from the Einstein's Big Idea blog. It's a question that frequently gets asked about E=mc^2...

Somu Selvaraj asks:
According to quantum theory of light,it contains the packets of quanta called photons.When electromagnetic waves like X-rays,gama rays,incident on the surface of certain metals the electrons on them absorbs that energy and are ejected and that electrons are called photo electrons. My question is 'if the electrons get the energy from the light whether the mass of the will increase or not? here the according to Einstein,
     E=mc2
if it absorbs that energy would the mass of the electron differs or not.

The answer is "yes" the electron's mass really does increase.  Let's pretend you are sitting in a lab watching the metal. After the electron absorbs the packet of electromagetic energy ( = photon), its total energy increases. Normally, we tend to talk about the electron as having had its kinetic energy (roughly, the energy of motion) increased by this absorption. Since the kinetic energy and therefore the total energy of the electron has increased, according to E = mc^2, the mass must also have increased.

Because the kinetic energy has increased, the velocity has also increased. In general, whenever an object increases its velocity, its "relativistic" mass increases. If it were to stop (lose all its kinetic energy) its mass would return to its minimum, called its rest mass.   The rest mass is always the same, but the mass is only equal to the rest mass if the object is resting!

For everyday objects like cars or bicycles, the velocities are much too slow for the effects of Einstein's theory of relativity (E=mc^2) to be noticeable, but for subatomic particles, it's not too hard to make them move fast enough for relativity to be very important. Particle physicists deal with relativistic particles everyday!

Accepting and rewarding Einstein

These two questions were posted a couple of days ago by one of our readers of the Einstein's Big Idea blog. I will take a stab at them!

Eduardo Avaria of Chile asks:

Was a part of Einstein's geniusness his obstination in "guesing" that he had the right and everybody else, even newton, and the entire physic scene was wrong (in his photon theory as an example)?

And as a secondary question, i want to know why the physicist comunity take so long to give cientists the recognitions they deserve. Why Einstein had to wait till 1921 to get the nobel prize he deserved since 1904? Or the photelectric effect was only a "touchable screen" to award him for his marvelous job?

I'll address the first question first. I wouldn't say that Einstein was "guessing" at his equations for relativity, etc. Despite his reputation as being "not very good at math", he was still quite decent at it by most people's standards! He used conceptual and mathematical reasoning to arrive at many of his big discoveries - including E = mc^2. He could back up his claims with solid mathematics.

It is important to stand by your work to make it stick, but he wouldn't have stood by his work with much conviction if it wasn't supported by solid reasoning and math.

Now I'll tackle your second question: why did it take 17 years for Einstein to get the Nobel Prize in Physics?  Seventeen years is actually not that long to wait to receive a Nobel Prize! Many scientists have had to wait much longer. And some couldn't wait long enough - they died before they had been rightfully honoured. Nobel Prizes are awarded only to the living, so it's often joked that you have to have a strong constitution to win a Nobel.

More importantly, new ideas take a little while to sink in with anyone - physicists included! Even Einstein's seeming simple and profound ideas took some time to sink in. We physicists are notoriously sceptical when it comes to new ideas and love shooting them down. If, after lots of shooting, a new idea espaces unscathed, then it is deemed worthy. That's one of the best features of science - new ideas must stand up to scrutiny - most seemingly great new ideas have holes poked in them and die, but a few survive and sometimes go on to change our perception of concepts as profound as time and space.

Radioactive salt in SNO

The picture on the left is a snap shot of the SNO event display from less than five minutes ago. The roughly circular cluster of orange dots are SNO light detectors that have "seen" light inside the detector all within 20 nanoseconds of each other. The event is probably caused by a radioactive decay of radioactive salt in SNO.

What the heck is radioactive salt doing in the detector you ask? We put it in a few days ago to help understand our detector's response to other sources of radioactive background and also to understand our response to neutrons. Sodium-24 is the radioactive isotope in the salt (NaCl = sodium chloride).

Fortunately, the half-life of sodium-24 is only 15 hours, so in a couple of weeks, there will be very little radioactivity left.  The sodium-24 decays by first emitting an electron (and an anti-neutrino which we don't see). This changes the sodium-24 nucleus into a magnesium-24 nucleus in an "excited state". Basically, the new nucleus is unstable so very quickly emits two gamma rays. One of these gamma rays can sometimes split one of SNO's heavy hydrogen nuclei (the "heavy" part of SNO's heavy water) into a neutron and a proton. This neutron then sticks or "captures" onto another heavy hydrogen nucleus. This in turn produces a high energy gamma ray which is visible in the SNO detector after it scatters an electron. The electron actually emits the light which is seen by the light detectors. 

Phew! That's not so straightforward is it. My apologies - I didn't want to lie to you about what really goes on inside SNO! Basically, for these radioactive salt calibration runs, we see the result of neutrons capturing on nuclei in the detector. Seeing lots of these events helps us to understand better how our detector works. Like a piano tuner tunes a piano to get just the right sound, we are tuning SNO to make it run as well as possible.

Car shopping

Since my last blog was about a new SUV, I will continue on the same theme and write about my recent car shopping experience. 

My wife, Pam, and I decided some time ago that we would get a new vehicle sometime before Christmas. This decision was based on the imminent arrival of our second child: due in early January! Our ever-reliable and virtuous Toyota Corolla is just too small for two baby seats, two adults and a dog.  So, we decided to get a bigger car.

From the moment we decided to get a bigger car, my wife and I agreed that a big SUV was out of the question for moral/political/social reasons. For aesthetic/psychological reasons I was also opposed to getting a mini-van. That left only one real option: a wagon.

These days wagons are cool - or at least I think they are cool. Unfortunately, not many car companies make wagons. They are too busy churning out ridiculously over-priced, and profitable, SUVs. Our wagon choices were quite limited. I was excited about the new Mazda 6 wagon (partially thanks to Tommaso's old posting about his Mazda 6 wagon). Pam liked the Subaru wagons: Forester and Legacy.

Early on, we decided we would buy a used car (2-5 years old) as cars lose ~50% of their value in the first few years. You pay a very high premium to own a new car. Our old Corolla was two years old when we bought it and it has been great for us.

My initial excitement about the Mazda 6 wagon faded when I realized how expensive they are. First, they are over $30,000 new, plus they came out only a year ago so used wagons are (a) virtually impossible to find, and (b) still expensive when you find one.  We test drove a Mazda anyway - it was great to drive (sadly). Fortunately, our next choice, a Subaru, looked much more promising. The Forester in particular gets decent mileage for a larger car (10 L/100 km in the city) and it is easy to find used ones for sale.

After much shopping, we found a very good deal on a 2000 Forester with very low kilometres. It is now ours, but we haven't picked it up from the dealer yet. My wife will get to do that later in the week. I will have to wait until I am back from Sudbury to take it for a spin.

There are only two downsides to the Forester. The first is that it is not the world's most beautiful car - I thought they were really ugly before I realized that the Forester would be a good choice for us. After this realization, I managed to convince myself that they are not nearly as ugly as I originally thought - honestly - no really - honestly! 

The second downside is that Subaru calls the Forester a "compact SUV". The acronym SUV makes me cringe - there's a lot of negative baggage attached to those three letters. The Forester really is a wagon though. The mileage is far better than real SUVs and it's not nearly as large or high off the ground; it's much more car-like. I'm convinced Subaru calls it an SUV just to try to sell more of them. I'm not fooled!

We should be set now. Just as long as there are no more babies... If that were to happen, maybe I could convince myself that I like mini-vans too. The mind is an amazing thing; it will do anything to minimize cognitive dissonance.