What I expect of my PhD students

Every graduate student needs to be aware of expectations.  Each adviser is unique and operates on different principles.  A small number view their students as a pair of hands to do the dirty work.  In the old days, some advisers expected their grad students to mow their lawn and do housework. A friend of mine from grad school had an old-school adviser who had him come to his place on the weekend for services.  However, most faculty members by that time had already moved into the modern era and this kind of despicable practice is no longer tolerated.

It is important that each student have an understanding of what they are getting into when they join a research group. Here I will explain what I expect.

My highest principle is thinking of a graduate student as a junior-colleague-to-be.  Even the best students start out incapable of doing real research.  They are clumsy in the lab and need lots of hard work to sharpen their analytical skills.  As such, my first criterion is that they be good students who like to learn.  That doesn't mean that they need to be straight-A students.  In fact, many A students make poor researchers because they lack creativity.

On the topic of classes, I believe that the more the better.  I encourage students who are in the middle of their research phase to take classes.  Ironically, the students themselves resist because they feel it interferes with research.  Even some of my colleagues prefer that their students not take courses that are not of direct help to the research at hand.  I strongly disagree with this premise. The process of learning new things sows new ideas.  I myself enjoy learning because these new nuggets of knowledge invariably get incorporated into my research, which leads to totally new and wonderful directions.

Principle 1.  Always keep learning from classes, reading the literature, and just thinking about crazy ideas.  If you feel yourself to be leaving your comfort zone, you are on the right track.  I expect my students to never stop learning and to be constantly pushing themselves.

An important part of being a PhD scientist is independence.  Grants, which support research activities, expect results.  Many advisers thus give their students a very short leash.  The end result is bad for the student's independence.  I prefer to give the student a specific assignment, and let her and him work on it for a year or so without giving them a detailed map of how to get there.  However, I do give lots of course corrections and teach them things they need to know along the way (or send them to the literature) if their struggles are based on missing information.

I once had a PhD student who complained that I seemed to be giving another student lots of attention while neglecting him.  I treat PhD and masters degrees differently.  The individual with a masters degree needs skills to survive in industry, while a PhD scientist is required to come up with new ideas and find ways to tackle a new problem.  Having said that, some of my best and independent students happened to be masters students who were quite capable of getting a PhD.

Principle 2. Learn to be self reliant early on in your research.  Read the literature and talk to others to gain the skills you need to do your work, but don't wait for someone to tell you what to do with those skills.  Constantly try new things in the lab or with paper and pencil to both sharpen your skills and generate new ideas.  You will make lots of mistakes along the way when not given step-by-step instructions, but making these mistakes and getting through them are the most important part of the experience.

I do not yell at my students, ever.  I may tell them when I am displeased with research performance, but if a student does not perform, (s)he will not get a degree.  Passing the Prelim and being in a research group is no guarantee of success.   I disagree with the idea espoused by the administration that we need to help the students along so that we increase our graduation rate.  Graduating a PhD without the proper skills and talents serves nobody.  A PhD degree is not a ticket to a good job.  It's the skills that the individual has mastered and the ability to think independently that makes him or her valuable to society.  A huge pool of unemployed physicists is not what we want to be generating.

It takes lots of hard work and perseverance to finish a PhD degree.  People often ask me how many hours they should work.  My answer is all the time.  If you are not excited by your work and don't enjoy thinking about physics beyond your area of expertise, then you're in the wrong field.  Academic jobs are tough to get, and real research jobs in industry are rare.  However, PhD physicists have lots of success in engineering jobs, which are more plentiful.  If you like to tinker, then engineering may be an excellent way to earn a good living while having fun.

A PhD degree should not only be a guarantee of skills, but of work effort and perseverance.

Principle 3.  Approach your research with a passion.  The benefit of enjoying your work, aside form the direct rush of endorphins, is that you will put in the time required to do a good job.

One of the most important attributes is perseverance.  Watching Star Trek, or other sci-fi shows/movies gives one the impression that scientists apply skills to very easily solve problems.  This is not the case unless a student is super lucky.  I have a long list of stories on the same theme;  students who would spend months trying to get an experiment to run, only to have to start from scratch to try a different approach.  Aside from being good problem solvers, the PhD degree is an imprimatur of a person that does not give up.

In my PhD work, I had spent quite some time building an experiment on a 5' x 10' table optical table, which was filled with all sorts of laser sources and optics, resembling a Borg city.  Each step in the process often required a step backwards.  After completing the construction of the experiment, it still didn't work.  I then figured out the reason, tore the experiment apart and rebuilt the whole thing on another optical table with another laser.  Luckily, it ended up working.  Only then could I start taking the data that was the topic of my thesis.

Principle 4. Don't give up.  When something doesn't work, don't shy away from the problem.  Work twice as hard.  This will serve you well in all aspects of your lives.  When I was a new faculty member, aware of the importance of getting grants, I would write two new proposals for every one that did not get funded.  After my first two years, I built a healthy portfolio of projects.

Many people do not recognize the creativity behind science.  Creativity is part of choosing a scientific problem to study, helps in problem solving, and leads to interesting new science.

Principle 5.  Be creative.  Always think about neat implications of what you are doing or find new ways of looking at old problems.  This skill is particularity important in the career of young scientists who want to make it to the next level.

Principle 6.  Be meticulously careful in your work. Do not publish sloppy results, which will come back to haunt you, and always apply the highest standards to yourself.  You should be more critical of your own work than I am of you as your  adviser.  On the flip side, do not let this attitude prevent you from finishing a project.  In the end, we can never be sure if we are right, and there will always be a mistake somewhere.  If a paper is perfect, it is not science.  When working in the unknown, there are always huge dark shadows in the areas not exposed by your searchlight.

Principle 7.  Be honest with others, but especially with yourself.  Many very good scientists have fallen into the trap of fooling themselves into believing in something that is false.  Consider cold fusion, N-rays. etc.  Design experiments that are resistant to experimenter bias.  Also, do not try to make data fit your adviser's expectations.  I need to know when an experiment contradicts my viewpoint.  And it goes without saying that you should never fudge data in any way or plagiarize the work of others.

Principle 8. Impress me.  When you graduate, I need to make an honest assessment of your strengths and weaknesses in the letter of recommendation, which will determine your success on the job market.  Follow all of the above principles.  Do not come to my office to ask what you should do next.  Tell me the issues you are having, your line of reasoning, possible explanations, and engage me in debate about the possibilities.  You should act as a junior colleague.  Don't worry about offending me.  I am more interested in getting at the truth than being right.  However, that does not give you the right to be caustic.

What I have posted above mentions nothing of the content of the work, which is of central importance.  A short post cannot cover the nuances.  To zeroth-order approximation, I expect the student to add a new piece of physics to the body of knowledge.  This could be a theory that helps us understand a phenomenon or the discovery of a new phenomena.  Fitting data to a mathematical expression is not enough.  The parameters of the theory must have meaning that is independently testable, be interpretable in terms of fundamental processes, and make predictions well beyond the domain of the original results that generated the theory.  Perhaps I will write more on the topic later.

If you approach everything in life with a passion, it will be a fulfilling one.   When you take a break from physics, make it count.  While I may seem one-dimensional in this post, I do find time for other activities.  Though I am not good at it, I play ice hockey with a passion.  I enjoy playing the piano and writing.  Taking a break from work is, in a sense, work.  During times of alternate activities, things percolate in the brain.  I have had the most profound revelations while driving my car in the middle of nowhere or playing the piano.  So, don't hesitate to take a break with intense activities.

I have to run now.  After I finish packing, I will take a short walk around San Diego, then I have to catch a plane back to Pullman.  Until then, get excited about physics.

Perhaps this time it may be right - taking a big chance

I wrote a while back how Shiva's measurements gave 0.29eV as the binding energies in our polymer/dye material (with an experimental uncertainty of 0.02 eV) which is responsible for forming domains that are at the heart of our theory of self-hearing .  I tried to figure out what interactions between molecules and polymer would give this energy and came up with a possibility.  But because I read the data tables incorrectly, I wrongly thought I had solved the problem.

When preparing my talk for SPIE a couple days ago, I drew the PMMA polymer chain with a molecule drawing program and added a few DO11 tautomer molecules to see where they would fit.  Miraculously, as a plopped the DO11 molecules on the page, I immediately saw that the NH from the DO11 tautomer cozies up to one oxygen in the PMMA polymer chain while the OH group naturally attaches itself to another oxygen in the chain, as shown above.  And he energy?  You got it; the sum of the two hydrogen bound energies is 0.30eV, a match.  The table below shows the energies of four types of hydrogen bonds.




There are always other possibilities that we have not yet considered, but this smells right.  Perhaps we are onto something.  Future experimentalists will allow us to test this hypothesis and zero in on what is going on when a molecule self heals.

This project has been one huge puzzle, were each new experiment presents to us a new piece.  It reminds me of how the discovers of the structure of DNA (Crick, Watson, and Wilson  ) pieced together cardboard cutouts of molecules to guess its molecular structure, and confirmed their results using x-ray scattering data from  Rosalind Franklin.  Incidentally, the story behind Franklin's contributions to the discovery of DNA and not being recognized  at the time makes for interesting reading.  I also recommend readers to check out Schrodinger's guess as the structure of DNA using simple physics principles.  The title of his very thin but fascinating book is

"What Is Life?: with 'Mind and Matter' and 'Autobiographical Sketches'"

I can imagine the thrill of discovery experienced by Crick, Wason, Wilson, and Farklin.  From little cardboard pieces and an "X" on a piece of film from an x-ray scattering experiment (shown above), they revolutionized our understanding of the workings of DNA.  Ironically, the forces that hold together the double helix reside in the hydrogen bond, the very forces that seem to be at work in our molecule/polymer system.

I am preparing my talks this morning, and plan to go on a limb proposing stating that the interaction between a DO11 molecule and a polymer chain  through hydrogen bonding underpins the phenomena of self healing.  I am not a chemist and have a naive view of the intricacies of how molecules interact.  But, I hope that my bold proposal will result in good feedback form my audience that will help us fine tune our models of the mechanisms of self healing.

I have been very excited in recent months by all of the discoveries that we are making.   Even if they end up being wrong, the process of the search for the truth is exhilarating.  Gotta run.  Too much to do.  And again, sorry for the typos!

Even teeny weeny discoveries are great fun

This morning, in the process of editing a paper, I made a small discovery. We have developed a new mathematical framework for determining the properties of quantum graphs in terms of the properties of the pieces. This work provides simple identities on the pieces that will allow us to determine general principles form the ground up rather than having to calculate the properties of the full graph.

I have to run because my wife is calling me to lunch.

Here is my email to my collaborators.

Your introduction to edge states was perfect. I liked the physical approach that leads to the formalism. In fact, its clarity was instrumental in allowing me to make a minor discovery (see below).

With regards to the paper, EDGE STATES ARE WONDERFUL! I am taking a break for lunch now, but FYI, I have been working soley on the appendix because I have done what I think is a really neat calculation which uses the power of the edge state. If you recall, in the past, we used the fact that the sum over all of the edges yields the full sum rule. However, it turns out that there are sum rules on each edge! The edge state formalism has allowed me to do this very easily. The result is given by Equation A20 of the geometry. I have pretty much dropped everything to work on this, but I will need to get back to preparing my talks for SPIE since I still have lots to do.

I suggest the following. I still need to reread the appendix because I was making changes while calculating -- never a good thing in terms of introducing typos. I will work on this after lunch. In the meantime, please check the appendix and let me know if I made any errors. The result is so logical that it seams right. I will then alternate between working on my talks and working on the paper.

Most likely, I will not go in to work today so that I can finish the paper in time to be posted on the archives tonight. Even these small discoveries are great fun.

It's all hanging over my head

I have too many things on my plate! Part of the huge pileup I owe to internet difficulties I had when visiting the east coast in mid July. Given all that needs to get done at the start of the semester, I regret that we agreed to a two-day vacation on Lake Chelan, which in reality will chew up 4 days when adding the overhead for driving. In short, I find vacations stressful.

Though I may be accused of whining, my intent is to describe the daunting tasks that are keeping me me busy since we got back from Philly. This post may make me appear illiterate, but please excuse all the typos. Don't have time to edit.

First, there is a backlog of papers that I am writing and editing.

1. My collaborator and I completed a piece of work almost a year ago on the gamma landscape that I still need to write up. This work shows that the problem of gamma is much richer than beta, and that the universal properties of potentials that are near a local maximum separate into several distinct classes. I have been working on this paper on an off for a while and plan to finish it soon. Working on it.

2. Xavi sent me his SPIE paper where he did some sum-rule gymnastics to show that a two-level model is unphysical. I checked the paper, so now it is out of my hair. Done!

3. and 4. Shoresh is giving a talk at SPIE on quantum graphs and a talk on how the energy spectrum affects the nonlinear optical response. I finished editing these two papers today and Shoresh has submitted them. Because I have a type A personality and hate even the smallest imperfection, I spend lots of time even on conference proceedings. Done!

5. and 6. Nathan has been patiently waiting for me to edit two huge papers on cascading - a process by which lower-order nonlinearities work together to attain an enhanced higher-order one, where we show that nature does not provide any loopholes for getting a bigger nonlinear response than calculated using the limits. That is my next priority. Given the complexity of this work, it will take some effort to plow through all the details.

7. I have been invited to write special review article for JOSA B with George Stegeman. Bob Boyd is also a potentially a coauthor. This paper has an upcoming deadline of a few months because the special issue is to coincide with one of the Optical Society's important anniversaries (I don't recall which one). Haven't started yet and am stressed out over the amount of work this will involve.

8. I have been invited to write a massive review article on sum rules and scaling for the high impact journal called Physics Reports. These are huge amounts of work, but I will have some help from my two coauthors. Need to start working on it soon.

9. Ironically, I was part of another group to write a Physics Reports review on organic nonlinear optical materials. This paper has been delayed by my coauthors, but if I need to write it parallel with the other one, I will have no time to sleep.

10. I am working on a paper with a collaborator on the nonlinear properties of air. This paper will be written in the near future since most of the data is in place. Will be working on this soon.

11. Shoresh is waiting for me to read his paper on Monte Carlo calculations on quantum loops. I know we will need to generalize the paper to include the band structure of the quantum wire. Lots more work!

12. An undergraduate REU student sent me his results on bent quantum wires. I eventually need to turn this into a paper. Luckily, he is traveling overseas for a year with minimal email contact, so this gives me an excuse to procrastinate. Back burner...

13, 14 and 15. Three papers are out for review: one on the diffusion mechanism in polymers, one one on transverse sum rules, and one a critique of a paper on nonlinear Miller's delta. Once these papers are reviewed, there will undoubtedly be revisions. Soon, another deadline!

16 and 17. Two papers have been accepted: one on the theoretical models of the heating mechanism of the photochemical effect and one on the... damn, I just forgot what is was while writing. Anyway, there will be page proofs to correct.

18. As I reported a while back, we finally finished the huge paper on AF455. The reviewer wanted to revisions. Xavi made the first set of revisions and I just finished making my changes. Took most of the day. I even managed to add another little piece of analysis that makes the results even stronger. I sent it all back to Xavi and he will make a couple of minor changes before submitting it. Hopefully in the next couple of days. (He too is busy.)

19. 20... I am sure I have missed something.

Now that I see this list, I am already getting more stressed out. There is more work than I thought.

I had good news that my NSF proposal would probably be funded, provided that I answer some questions about the project. That brings me to proposals. I have actually been writing fewer proposals than usual because I am finding that I cannot keep up with everything as it is. If I get more funding, I will need to do more stuff. Here is what I am up to.

1. I responded to NSF about my proposal. It actually took me a couple of days to do so because I need to be careful not to say something stupid. I submitted my answers and a day later was notified that I forgot to explain my educational plan. I rewrite the damn abstract to stay within the work limit and resubmit it. They tell me it's all in order, so I cross my fingers and wait for the final decision.

2. I need to write a report to NSF for my present funding. It takes forever filling out the forms. My program manager likes to see lots of technical details so I try to upload a huge pdf file. The system balks and I have to contact technical support. I am procrastinating.

3. The Air Force needs a report for our grant. Ben writes a first draft, then I spend a day rewriting it. We go back and forth a few times to iron out problems. The report is done over the weekend - just in time.

4. Luckily, my AFOSR report was due before the trip to Philly. Already done!

5. I need to court the Air Force to renew my funding. Because of the problems with the federal budget, a grant that should have been of 5 year duration is cut after one year. I need to generate creative ideas that will convince the air force people that our work is critical to them.

6. Our lasers are getting old. Need to write an equipment proposal that is due in September. Need to start work on that soon. There are lots of complex forms that need to be filled out. Luckily, office staff can help.

7. We are doing exploratory work on a secret project. I'll divulge details later after we write a proposal on the topic.

As a faculty member, and unfortunately associate chair, I have all sorts of other work.

1. I am on a search committee to hire a new office staff person. Emails go back and forth constantly as we go over folders and determine who to interview. Then there are interviews and eventually an offer and negotiation for salary, etc.

2. A recent announcement informs us that the college of sciences may be merging with liberal arts. Everyone thinks its a bad idea except for the administration. Looks like they want to do it. I need to go to meetings.

3. Since the chair is away, lots of things to sign. travel vouchers, etc.

Not enough time, so I am going into stream of conciseness mode to finish this post. Don't know why I am wasting the time...

Am working on a couple of promotions of our faculty. Will be getting a bunch of reports from external reviewers. Will need to go over everything, call a faculty meeting to decide on each case, and then represent each case at the COS T&P committee meeting.

Having been a professor for over 2 decades, I get solicited to write letters of recommendation form students who have graduated as long as 20 years ago. This includes my graduate students, grad students on whose committees I have served, undergrads, as well as students who have taken my classes.

There are always professional service activities. I always get lots of requests to review papers. Since I publish a fair amount, I should be reviewing 2 to 3 times as many papers as I submit. I am on the reviewing list of a few dozen journals. A week does not go by without being asked to review, and many weeks I get several "invitations." Just to decide which ones I will review, which ones I will pass along to others, or which I will just decline takes some time (I need to look over the manuscript to decide). At the moment, I have a couple of reviews hanging over my head. Sure, I can sometimes pass along reviews to my grad students, which I do to teach them about the process, but it take me longer to show them how its done or to edit their reviews than it takes for me to do myself.

And then there are tenure and promotion letters that I need to write for faculty at other universities. I need to carefully read the thick packages for each case to do a competent job. These days one can get sued if the individual does not like the result. Sitting on such a review now.

Then there are conferences to organize as a member of the organizing committee or program committee, which decides which papers to select and who to invite to give a talk. Luckily, only on a couple low-key committees now.

Then there is teaching. Need to prepare my syllabus for my class this fall. Also, in the week before classes start, I am running a discussion group on a common reading book at the honors college and am involved in orientation for the newgraduate students.

In grant administration, there are always budgets to manage, who gets appointed on an RA, how do we spend money on time, how we re-budget colors of money to buy what we need. Just yesterday, we exchanged an item leading to a credit on the equipment part of a grant. Have to figure out a way to spend it before the grant runs out in a few weeks. Don't want to waste precious funds. Also, get budget statements every month. Need to make sure we are not overspending or underspending.

Then there are emails with collaborators that seem to come at me form all directions. We are starting a new collaboration with Nathan's new group. Communicated with the PI yesterday with a couple of back and forth emails. Then there are colleagues who are giving talks who need slides or colleagues writing proposals who need support letters. These trickle in all the time.

A big pain is updating my CV. Seems to take as much time to document what I do as doing what I do. Not really, but seems that way.

And then, of course, there is managing my research group. I need to meet with each student typically every day or at least every other day. There are always puzzling data, equipment that is breaking down, or new experiments that need to be designed and built. Everyone's problem weighs on me like it's my own. Well, it really is my own. We work together to get ideas and troubleshoot. Takes at least a couple hours a day and often most of the day.

Then there are thesis committees, both my own and other students in the department. To edit a student's dissertation takes me about a month of full time effort. Reading and understanding a dissertation from another group can take a day to a few days. In addition, during the writing process, there are many scientific problems that usually get ironed out. Will have at least a few of these during this academic year.

When the semester starts, I will need to prepare for each lecture, which takes me one to two hours per lecture hour if I already have prepared notes. When preparing a new course, it takes almost all my time. Last academic year I had a new grad class each semester. Then there is one full day a week grading, usually Saturday, and some time to prepare each exam. And there are office hours to answer student's questions. Teaching (aside from grading) is one of the more fun parts of the job.

Then there is all the paperwork. Need to sign off when students change their program of study (i.e. which courses will count toward the degree), figuring out how to juggle courses to make sure the students meet requirements in years where a required course is not offered. The office staff is great at figuring these things out. To many little things to list hear.

When there are budget cuts, we need to make painful decisions on how to make cuts without impacting our mission. Last academic year, we spent quite a bit of time determining which things could be cut and by how much. Some of these cuts are being implemented this semester. More cuts are in store for the next academic year. Thus, more work and more meetings.

What little time is left I devote to thinking about physics and doing some work with pencil and paper. I need to be generating new ideas that will become the focus for future research. I find thinking to be a pleasurable activity. Luckily, I generate more ideas than I could possibly pursue.

In the midst of all of this work, I get annoyed with the clumsy system used by our university to enter out activities for the year. My main complaint is that it was designed with the mediocre individual in mind, and therefore takes much longer to complete if you are really doing lots of things. It takes me almost 2 days each year to fill out the damn template.

In the spring, I will be doing annual reviews of the faculty once again - a two-week full-time process. Since the chair will be away most of the time, I will undoubtedly be going to many more meetings.

Then there is the stress of travel. First, preparing a talk and then making all of the travel plans, then when returning, putting together all the receipts for reimbursement. In addition to the time away, it probably takes a few days to prepare. Typically, I travel a few weeks each year (maybe an overseas trip this September - I hate traveling during classes). Many of my colleagues are on the road much more. Don't know how they do it.

I am editor of two journals, which requires assigning editors and making decisions on manuscripts. The work comes in spurts, like dealing with a plagiarism case last academic year. Luckily, not to much activity this month asside from needing to bug authors to submit their manuscripts. You know who you are!

To fight the stress, I try to play hockey twice a week. For these few hours, I forget about all of the work that is piling up. Also, at about 10:00pm each night, I spend 30 to 45 minutes studying Italian. Turns out I end up only having time for this 3 nights a week. But, I am compulsive and continue to work on it to meet my goal of someday being fluent. Doesn't feel like it will ever happen, but I continue to try.

Other than these breaks, I am usually working 7 days a week. True, I need to take a break (usually on Sundays) to pay the bills; and of course, there are the occasional social outings. But, that is why entropy seems to continually take control of our home.

...ping... Just got an email to review another paper and a request to write a letter on behalf of a colleague for a sabbatical. ...ping.. problem with a grant budget ...ping... an email about the merger of COS and CLA. ... Gotta run to get some real work done. (Glad I have two big screens with about 20 windows open at all times so that I can multitask.)

Later...

Sophistication versus Understanding

I attended the SPIE meeting in San Diego over the weekend, where I gave an invited talk about work done in collaboration with David Watkins of the Math Department. The meeting was in a small room with perhaps a couple dozen attendees, all experts in organic nonlinear optics. We had a good time exchanging ideas and throwing about some new thoughts.

As I have mentioned in previous posts, I find travel physically draining. So, spending eight hours en route to San Diego on Saturday and eight hours on Sunday to return home took its toll. While I usually work on weekends, I find it much more relaxing than sitting on an airplane. So, I started the week in an uncharacteristically bad mood.

To add insult to injury, I learned on Sunday and Monday that two of my papers were outright rejected -- not something that I commonly experience. In addition, a paper submitted by my collaborators, to which my contribution was relatively minor, was also rejected. Thus, in a span of three days I had more rejection than in a typical decade. I think that my darker than usual mood was warranted given the extraordinary circumstances. In fact, I entertained the notion of quitting the professional life of physics altogether.

After a good-night's sleep, my mood dramatically improved so on Tuesday morning, I wrote a levelheaded email to the two editors who had rejected my papers. In the process of composing these letters, I realized that science has turned into a big efficient machine, with creativity a reluctant causality.

For more than three decades, lots of people have been expending a great deal of effort to make better molecules. In parallel, computational methods are getting more sophisticated so that theoretical chemists can calculate the properties of ever-larger molecules, taking into account more subtle effects and getting more accurate results. Similarly, chemists have made a huge number of very complex structures, many of which are pieces of art, such as the ever-branching dendrimers.

My own work, which uses sum rules to understand the nonlinear optical response of quantum systems (which I started ten years ago), illustrates how simple but powerful ideas can arise even in a mature field. The basic question that I asked was if there was a fundamental limit to the nonlinear optical response. The answer was a resounding "yes." This limit is not based on practical considerations, but on very fundamental quantum mechanical principles that span the basis of chemical reactions of life and govern the flow of electrons in electronic circuits. If the fundamental theory of quantum mechanics were to be wrong, then the world would be alien to us. In fact, we probably wouldn't exist. In short, I feel that my fundamental limits calculations stand on solid ground.

I expected great admiration for my theory when I first presented a talk on the topic a decade ago. Instead, I got some very nasty comments to the effect that my work was an insult to all the hard-working chemists who were trying to make better molecules. Who was I to say that it was not possible to do any better? Though that sentiment did not reflect my intentions, mother nature DOES place limits on what is possible.

To put this into perspective, my calculation does not imply a single numerical limit, but rather a limit in the presence of a contraint. For example, to investigate the largest possible area is nonsensical. It makes more sense to determine the largest possible area given a fixed perimeter. Similarly, when studying molecules, it is more appropriate to determine the largest nonlinear response for a given molecular size. Since size is not well defined in a quantum system, we used the more abstract concept of scaling.

The bottom line is that after three decades of research, the best molecules fall short of the fundamental limit by a factor of thirty. While people have been making bigger molecules with a larger nonlinear-optical response, the intrinsic nonlinearity has not changed since the birth of the field. That's why one of the reviewer's comments was particularly annoying. (S)he was critical of our simple fundamental approach as passe in light of all the sophisticated and precise methods available. Ironically, our simple approach has been the only one that has led to an improvement in the intrinsic hyperpolarizability.

Being a scientist, my priority is to understand, not to participate in the frenzy of doing the most sophisticated calculations. I prefer to study broad principles that apply to all systems rather than seeking higher precision in more complex calculations that apply to specific molecules. My long-term goal is to build an understanding of the fundamental issues that identify universal properties of systems that approach the fundamental limit. And in this quest, my small effort continues.

I end this post with good news. In response to my emails, both editors reversed their decisions and are giving us the opportunity to submit a revised manuscript. While I am concerned that the trend of sophistication worship is wasteful, I take comfort in the fact that our group is supported to continue our work. Perhaps a time will come when I will become one of the dinosaurs that was left behind, but for now; I take great satisfaction in my research and the potential it has for making a lasting contribution to the body of science.