Published, Not Perished!

I just published my first paper as lead-author! Today I thought I'd give you an idea of what the process was like, and what the paper is actually about.

Choosing a Journal
There are many physics journals out there, each covering different divisions of the field. Our first submission was to Classical and Quantum Gravity, which specializes in general relativity. They rejected us outright (more on that in a moment), and so we had to find another home for the paper. Our next choice was Physical Review D, a subset of the 125 year old Physical Review journal. D covers particles, fields, gravitation, and cosmology. There's an associated journal called Physical Review Letters for short, breakthrough papers – This is where the first detection paper was published. All these journals are under the management of the American Physical Society. When I went to one of their meetings last year, I performed some shameless pandering, which appears to have paid off:

Review Process
When a paper is submitted to a scientific journal, it gets distributed to one or more referees. These are fellow scientists who are in related fields, hence "peer review". The referee's job is to read the paper, give suggestions for improvement to the authors, and recommend to the journal whether it should be considered for publication.

As I mentioned above, our first submission was with Classical and Quantum Gravity, which send it on to two referees. After several weeks, I got an anxiety-inducing email saying that the two reviewers had not agreed in their decision on the paper, so it had been sent on to a third. The trouble was, we didn't know what the disagreement was over: It may have been that one thought it was ready for immediate publication, while the other had modifications to be made first. As it turned out, one wanted to reject it outright, while the other wanted significant changes. The third also dismissed it, and the paper was rejected.

Because the referees write reports instead of simply giving a yes/no/maybe answer, we were able to see the problem: They didn't see any innovation in what we had done, and thought it was more suited to a technical note. That led us to rewrite the paper to put greater emphasis on the concepts we were demonstrating, rather than the technical implementation.

After rewriting, we submitted to Physical Review D. The referees there still thought it needed rewriting, but were willing to consider it if we satisfied their requests. After several back-and-forths, the paper was accepted!

Copy Editing
At this point, the paper was passed off to the copy editing department, which did final checks and formatting. Every reference we used needed to be connected to a known object, so there were several they requested more details for, so they could be properly matched.

Preprint
Typically, academic journals require paid subscriptions to access papers. Most universities will have an account they share with their students and faculty, but for anyone else the paper may be impossible to access. That's where preprints come in – These are earlier forms of papers that may or may not appear in journals that are offered for free online. In physics, we have the arXiv (pronounced "archive" – the X is the Greek chi). After our earlier submissions, we posted a version of the paper there, but since PRD allows the accepted copy to be shared as well, that will go online Monday.

Content
But what's this paper actually about? I talked about aspects of it before while writing my thesis. The idea is this: When we make an observation of a gravitational wave, we want to know when that was emitted from its source, so we can line up our observations and figure out what the source is doing. That's a little harder than it sounds though, since we're making our observations here on Earth, which moves through space. That movement is more complicated than you might think.

The paper is about approximating the timing calculation so that we can compute it more efficiently. The maximum allowable error we chose was 42 microseconds, which translates into an error in position of about 12.5 km, or 8 miles! To get the Earth's position that accurately, you can't just use an ellipse – There are all sorts of little wobbles from the Moon, Jupiter, and Saturn.

To account for those wobbles, we imagined looking at a small patch of sky, like the ones we use in our searches, and getting the exact emission time at the center of the patch. Then we asked, "What's the difference in emission time between any point in the patch, and the center?" By using the difference in time, we were able to get an efficient model that stayed within our error limits.

It was an interesting experience to take a paper through the review and publication process, and I can't thank enough my co-authors Keith Riles and Vladimir Dergachev for their help reaching this milestone. I look forward to many more successful publications!

MeteoRing

Shortly after I mentioned my girlfriend Marika, I'm delighted to announce we got engaged!  A few days later, we went shopping for my ring, which arrived earlier this week.  The metal used in the ring comes from a meteorite that hit the Earth during prehistoric times, and scattered over 8,000 square miles in the region of Africa that gives the meteorite its name: Gibeon, Namibia.

The unique design on the surface of the ring is called a Widmanstätten pattern, and is evidence of its extraterrestrial origins.  The pattern forms when a mixture of nickel and iron cool over a long period of time, on the order of 10 million years.  Such slow cooling isn't possible on Earth, where the rest of the planet can serve as a heat-sink.

The name "Widmanstätten" comes from Count Alois von Beckh Widmanstätten in 1808, but the first published study was actually from G. Thomson in 1804.  There's quite a story behind why he was not acknowledged (from Wikipedia):

Civil wars and political instability in southern Italy made it difficult for Thomson to maintain contact with his colleagues in England. This was demonstrated in his loss of important correspondence when its carrier was murdered. As a result, in 1804, his findings were only published in French in the Bibliothèque Britannique. At the beginning of 1806, Napoleon invaded the Kingdom of Naples and Thomson was forced to flee to Sicily and in November of that year, he died in Palermo at the age of 46.

It seems like a perfect choice for an astrophysicist, and a wonderful start to the next chapter of our relationship.  Thanks Marika!

I Can RELATE!

After an exceptionally long break, I'm back again!  It turned out the combination of coursework and cancer recovery were too much to handle on their own, let alone continuing with this blog.  I took a break from my program for a year and a half to work for a private company, then came back and finished up classes and exams.  I'm now doing full-time research with my advisor Keith Riles, studying gravitational waves using LIGO.  This summer, I participated in a seminar called RELATE – Researchers Expanding Lay-Audience Teaching and Engagement.  The program culminated in recording a short video summarizing our research, which I decided would be a great way to bring back this blog.  Take a look:

As always, questions are welcome!  I'm hoping to be back here about once a week; in the years I've been away, I've kept a list of potential topics, but I can always use more suggestions.

Happy Anniversary

I've been too busy with my first semester of graduate school to post anything here, but I wanted to take a moment to recognize the one year anniversary of my cancer diagnosis.  You can see from the picture that my hair is coming in nicely, though I have some thin spots on the sides of my head where the proton beam entered.  It was a rough first semester, dealing with the fatigue that commonly follows radiation treatment, but I made it through.  My last grade arrived this morning, showing that I just squeaked by the acceptable GPA.  I'm optimistic that I'll be back to my old self within a few months.  Once again, I'd like to thank everyone who helped me through this, but most of all, my parents.  They have provided undying love and support during this difficult time, and it brings a tear to my eye every time I consider it.

Light Rail

I have returned from my trip; big thanks to everyone who hosted me, and showed me a wonderful time.  I have a couple post ideas kicking around from my travels, but I thought I'd take a minute to give a quick primer on the special relativity issues I mentioned last time.

Special relativity rests on the idea that the speed of light is constant.  This may not seem like such a significant statement, but you have to consider that it means the speed is always constant.  Normally if you were chasing after something, all you need to do is go faster than it, and eventually you'd catch up.  However, if you tried that with light, no matter how fast you went, its speed would always appear to be the same amount faster than you.  This leads to some interesting effects.

Imagine we construct a clock that uses light as its timekeeper – it contains a hollow tube with a beam of light that travels down it, bouncing off each end; each bounce is a tick.  It might look something like this:

 

Now suppose we strap this clock to a rocket, and watch as it flies by.  It would look something like this:

 

The light is still going at the same speed, but it has to travel a greater distance, so the tick that we measured earlier has been made longer by the movement.  This is the relativistic effect known as time dilation.  Most other interesting effects follow from similar thought experiments.

One of the important restrictions of special relativity is that it only applies in an inertial frame, that is, a perspective which is moving at a constant velocity.  Technically, it doesn't quite apply to the situation I talked about last time, since my train had to accelerate up to speed, then slow down again, but we can adapt it as long as we're careful.

While on the train, clocks outside will appear to be running slower than my own, but since I accelerate before and after such observations, they are potentially invalid.  However, someone outside looking at my clock would be correct in noting that it appears slower than theirs.  Since the person outside stays still during my entire trip, their observations must be correct.  If the train takes a time t according to the stationary person, then they will see a time t/γ pass on my clock.  Plugging in the numbers from last time gives the 95 picosecond difference I mentioned.

Walkabout

(Another old t-shirt design.  Credit goes to my dear friend Jen Trinh for the wonderful Einstein drawing.)

Tomorrow I'm heading off for a trip around the East to visit friends and family before I disappear into Michigan for grad school.  I probably won't be posting anything here for about a week, but the long train ride ahead of me got me thinking about the possibility of high-speed travel to other solar-systems.  I wondered about the relativistic effects of my own travel – my train ride shouldn't actually feel like 6 hours, since I'll be moving.

In special relativity, traveling at a velocity v causes time to slow by a factor of

The faster Amtrak trains average about 63 mph, giving γ = 1 + 4.4 x 10^(-15).  That means that while my trip may last 6 hours, it will feel 95 picoseconds shorter than that.  What a timesaver!

The Deed is Done

Today was the last day of my proton radiation therapy.  This marks the end of my cancer treatment, though I still have a few check-ups and a lifetime of periodic MRIs ahead of me.  I couldn't have made it this far without the incredible support of all my friends and family, but there are a few people that I think deserve special recognition and thanks:

• My optometrist, Brian Wadman, who first noticed my swollen optic nerve and sent me for the MRI that revealed my tumor.
• My neurosurgeon, Ziv Williams, who evidently heeded my warning that my brain is about all I have going for me.
• My oncologist, David Ebb, who planned my treatment and kept a watchful eye over me throughout the ordeal.
• My nurse, Patti Scott, who would smile and laugh with me as she drew tube after tube of blood samples from my chest-port.
• My radiation oncologist, Shannon MacDonald, who was a match for my geekiness as she explained the inner workings of the MGH cyclotron.
• My mother Sally, who kept at work during this difficult time, providing the top-notch health insurance that allowed me to be treated.
• Most of all, my father Steve, who has been my roommate, nurse, chef, personal trainer, secretary, biographer, chauffeur, and friend during the worst 7 months of my life so far.

12 Stories High, Made of Radiation

Tomorrow, Steve and I start our daily trips into Boston for my proton therapy treatment.  The doctors have warned me that it can leave me pretty fatigued, so I'm not sure yet if I'll be up for doing more posts.  I have one almost finished about the shower in our new condo, but it's run into some complications I haven't worked out yet.

I'm going to try to stay active here over the next 6 weeks of the treatment, but I make no promises.  In any case, thanks again to everyone who's been reading.  Feel free to leave suggestions/questions for future posts in the comments.

Wonder

Just a quick post to point out one of the Swarthmore commencement weekend speeches I really enjoyed: Scott Gilbert's remarks at Last Collection.  I feel that his description of wonder is really what this blog is all about.

Works in Progress

Sorry for the long silence; I've been working on a couple different posts, and both have run into problems.  I'm going to be heading off to Swarthmore this weekend for Senior Week and Commencement, so I'm not sure if I'll have a chance to finish anything, but I thought I'd tell you a bit about what I've been thinking about, in case you want to express an opinion about which I should finish first.

Remote Controls - I was watching some TV a couple days ago, and it got me thinking about the way remotes work.  The questions that came to mind were: How many times can the beam bounce off the walls, and still produce a usable signal?  How long does a single command last?  How much could the signal spread out, and still be usable?  I started doing the calculations, but I ran into problems trying to sort out the weird units involved.  (Lumens per steradian?  Seriously?)

Weather Interpolation - Steve runs an electronic weather station in Ashfield that uploads its data to a site called Weather Underground.  I thought it would be interesting to try taking various data from the site (such as temperature) and interpolating between nearby stations to determine the approximate weather in places that didn't have a station.  I've been trying to automate the process with a Perl script, but it's been too long since I did any programming aside from Matlab's insane scripting language, so I'm having some trouble.

Let me know in the comments if one these piques your interest, or feel free to suggest your own idea.

Triumphant Return

I was released from the hospital yesterday afternoon, and, while I am still a bit nauseous, it's nice to be officially done with chemo.  While I was away, a few of you wrote in questions, either by email or comments, and I thought I'd take a moment to answer them.

Chris asked about this post, "How about getting your equations from the Lagrangian approach?"
Yes, that is a much better idea, and I may do it that way when I come back to this one.  I completely forgot about Lagrange, so thanks for the reminder (and shameful apologies to Matt Mewes if he's reading).  For those who don't know, the Lagrangian approach is an alternative to Newton's methods that is completely equivalent, but often is easier to work out in cases like this, where there are no dissipative forces, like friction.

Jim asked about this post, "Shouldn't velocity enter into the Crr term, thus changing the differentiation? I can't believe you get the same rolling resistance at 20m/s as at 1... And secondly, doesn't part of the force go into changing the wheels' angular momentum?  Do you need a -I*omega term on the right side of that equation?"
Rolling resistance is a bit dodgy, since the whole thing's an approximation anyway, but you're right that using a version that accounts for velocity would have been more accurate.  As far as the angular momentum, I think I'm ok neglecting that in favor of the overall linear momentum.  If you wanted to get into the actual construction of the chairs, you might need to consider it, but assuming everyone has the same design, I think we can do without.

Bob asked about this post, "I read your blog about noise cancellation and was wondering if you could explain how noise cancellation headphones work – I’m assuming they only deal with the problem in two dimensions?  Would it be possible to have two French horns properly situated in relation to an observer so if they blew the same note you would hear nothing? Or do the harmonics make this impossible?"
The key to noise cancelling is that sound is a pressure wave – a series of pockets of high and low pressure.  All you need to do to cancel a sound is absorb the high points, and fill in the low points.  A perfect way to do this is by using the very sound you're trying to cancel, but shifting it slightly so that its low points line up with the original high points, and vice versa.  This becomes more difficult as the frequency increases, since even small misalignments can increase, rather than decrease, the noise.  The timing required can really only be done electronically, so your proposed situation would require robot horn players using identical instruments.

Keep the questions coming; I'll be trying to post often this week to keep my mind off feeling sick.

On Hiatus

I've been low on energy the past couple days, and tomorrow I'll be heading in for my last cycle of chemo, so don't expect new posts for the next week or so.  Feel free to send me suggestions for things to look into once I'm out, either in the comments or by email.  Thanks to everyone who's been reading so far; it makes me happy to see so much interest in science.

Introduction

Since I was very young, I've known I wanted to be a scientist, but it wasn't until high school that I figured out exactly what field was for me.  I took my first physics class in 11th grade, and I was deeply impressed by how it explained everyday events with simple equations.  I began to see everything in terms of physical laws, and that's what this blog is all about: Looking at how physics applies to things I see in my own life.

Of course, one of the other characteristics of physics is making simplifying approximations, so sometimes I may reduce a complex situation to a more manageable one.  If you object to a simplification, or think I've made a mistake, or just have a question about my methods, please let me know in the comments.  Like any good scientist, I welcome peer review.

I don't have a rigid posting schedule in mind; I'll really just be adding things as I think of them.  At the beginning, I'll probably be posting unusually frequently, since I have a backlog of ideas, but then things will probably slow down a bit.