The Need for an Interdisciplinary Approach in Physics

We all know that physics, and science in general, has made a lot of progress in recent decades. There are, however areas in theoretical physics which appear to have reached a deadlock. An interdisciplinary approach may be one way to help alleviate stagnation in these fields. Unfortunately, very little and essentially no progress is being made to explore overlapping ideas in physics.

I have a PhD in particle physics but with time have worked in several other fields of physics. I have published a paper in condensed matter physics, quantum mechanics and have recently started working in plasma physics (lets see where this goes!). What I have noticed while working in these sub-fields is that physicists who are working in their respective fields are mostly unaware of the progress in other sub-fields of physics. In many cases, physicists in these different areas use the same equations but never share insights with each other because they are unaware of each others work. This is exactly what let to my first single author paper during my PhD. I found that particle physicists working on Lorentz violation employ a term in the Hamiltonian which was very well known in contemporary condensed matter physics, namely, the Rashba interaction term.  Particle physicists working on Lorentz violation, however, had no idea about the use of this seemingly ubiquitous term in spintronics.

I believe, and have learned from experience, that a plethora of new insights can spur out of an interdisciplinary approach in theoretical physics. Several areas of physics appear to have reached a deadlock when it comes to testing new theories and it appears that we are trying to continue digging the same hole instead of searching for new ones. Perhaps, an interdisciplinary approach might help improve this situation. This however appears to be difficult in the present academic culture, especially in the US. There are however institutes such as the ICTP in Italy where a first step can be taken. A first step, for example, can be to setup an interdisciplinary department for physics and explore the implications of overlapping ideas for various sub-fields in physics. In addition, we need to encourage the young generation to come up with new approaches to solve the unsolved problems in physics. Any major breakthrough in physics seems difficult unless we introduce new ways of addressing contemporary problems.

The Hierarchical Nature of the Particle Physics Community

The high energy or particle physics community works in a very different way from communities corresponding to other sub-fields of physics, for example, the condensed matter community. The fact that experiments in the particle physics community cost millions or billions of dollars implies that theories cannot be tested in a short span of time. For instance, the Large Hadron Collider cost around a billion dollars and the total cost for finding the Higgs boson was around 13 billion dollars. It took around 50 years to test the theory of supersymmetry and the lack of its signatures has lead the field into a deadlock.

As a result of this lack of experimental tests over large spans of time there is a natural implication on the nature of how the community functions. What happens is that the smartest people in the best  institutes naturally settle on the top of the hierarchical structure of the community. They mainly decide which ideas will be the most intriguing ones and the rest of the community follows them because they do not have any experimental benchmark to follow. Having a PhD in this field I experienced how jobs are so easy to find if you are working on the popular ideas in this field. During my PhD, I came up with an idea on my own and published a single author paper. I was quite excited at first and thought that my job prospects will increase significantly. But it turned out that this paper of mine had almost no benefit in my job search, only because the community was not working on such ideas.

I further got a better understanding of this hierarchy after reading Lee Smolin's book "The Problem with Physics". He points out in his book that few years back not working on string theory or something close to it meant an end to your career in particle physics. Another physicist who frequently writes about such ideas is Sabine Hossenfelder. She recently wrote a book "Lost in Math" that is on my to-read list. I strongly recommend these two books to the readers.

On the other hand, the other fields of physics such as condensed matter physics, Earth physics, Plasma physics, etc are much more progressive fields. This is because theories can always be tested with experiments and you do not see such hierarchies there.

Is there a way to deal with this problem? I am not sure. Lee Smolin has addressed some solutions in his book. I think one way out of this problem is for the particle physics community to be open to ideas from condensed matter physics. For example, a mechanism that the particle physics community adopted from condensed matter physics led to the discovery of the Higgs boson. Contemporary condensed matter physics is progressing at a very rapid pace whereas particle physics has reached a deadlock. This is however difficult because in most of the cases particle physicists look down upon this field of physics and I have seen particle physics joke about condensed matter physics. Well I guess the arrogance of the leaders of this community may keep it in a deadlock for a long time until young particle physicists realize that they have to find their own ways!

One of the Most Ignored Equations in Physics

We have all heard of the Schrodinger, Dirac and Klein Gordon equations and these equations are extensively used in modern physics. In addition, almost every book on non-relativistic and relativistic quantum mechanics discusses these equations. There is however one equation that is rarely discussed in contemporary modern physics literature and that is the Levy-Leblond equation [1]. The only well known book that, in my knowledge, introduces this equation is Greiner's advanced quantum mechanics book. In this article, I intend to highlight how important this equation can be in contemporary physics.

I claim this because I did not know about this equation as well until I discovered it myself [2]. During my PhD, I went on a quest to discover new ideas and this equation was one of the ideas I discovered and got the paper published as well. It was after around two years of publishing this idea and a follow up paper when I came to know that this equation was proposed around 50 years ago by Prof. Levy-Leblond. My approach in the paper, however, was quite different and, in particular, I solved a well known problem in quantum mechanics namely the step potential problem which was not done by Prof. Levy-Leblond in his original paper. More interestingly, the editor of the journal I published in was a well known Nobel laureate in physics. One of the referees was so excited about the equation that he/she called it something new after a 100 years. I contacted several well known physicists and they all suggested new insights that I can get from these equations but none of them knew about the Levy-Leblond equation.

After finding out about Levy-Leblond's equation I contacted Prof. Levy-Leblond and he acknowledged in his reply that independent discoveries are always made in science. He was also amazed that the editor and the referees did not know about this equation. This experience taught me the political dynamics of the physics community and how the community can have its own biases. Its amazing that equations such as the Schrodinger, Dirac and Klein Gordon equations are so popular and frequently appear in lists of beautiful equations in physics, whereas the Levy-Leblond equation is rarely mentioned. In my view, I think one of the reasons physicists and in particular particle physicist ignored it was that it is not Lorentz invariant.

The Levy-Leblond equation introduces spin in the non-relativistic limit and can lead to several new insights as I have shown in my papers. It is the analog of Dirac equation for non-relativistic quantum mechanics. I believe that this equation may be useful in contemporary fields like spintronics which focus on manipulating the spin of non-relativistic electrons. I have continued to work on this equation [3,4,5] and keep coming across referees who do not know about this equation and think that the calculations have already been explored without giving any strong references. I hope that this article brings attention to this beautiful equation as well and we as physicists learn to avoid such mistakes in the future! 

[1] https://projecteuclid.org/euclid.cmp/1103840281

[2] https://link.springer.com/article/10.1007%2Fs10701-015-9944-z

[3] http://iopscience.iop.org/article/10.1088/0256-307X/34/5/050301/meta

[4] http://www.ijqf.org/archives/3574

[5] https://arxiv.org/abs/1705.10409 

Virtual Particles

So, what is the deal with virtual particles? I am a particle physicist by training but I was curious as to what are the available answers on the web regarding these particles so I spent quite some time in searching online. I want to give you a heads up that the views I will be describing here are going to be quite different from what other particle physicist say about these particles.

If you have been following my blog, you might have noticed that I am a big fan of Lorentz violation. I believe that particle physicists are too biased when it comes to Lorentz symmetry and they ignore to even say the term Lorentz violation when it is apparently present in some cases, like CPT violation.

So you might have guessed by now. I think that Lorentz violation has something to do with virtual particles. Real particles obey the "on-shell" equation, i.e.,

 

or

This equation is not obeyed by a virtual particle, i.e., .  In other words, these particles do not obey the dispersion relation of a relativistic particle. So it appears that these particles might be described by Lorentz violating operators. Its weird that particle physicists, whenever they come across things like these they devise these fancy names as a cover for their biasness. Moreover, they try their best to come up with explanations that sound very convincing but in reality are not.

Let me give you an example, the Higgs field is a tachyonic field, which means that it is described by an equation that allows for faster than light travel speeds. When asked about this they say that it is not a physical field while the Higgs boson which is a fluctuation of the Higgs field is the physical particle. Oh, so the Higgs boson is a fluctuation in a non-physical field, great! As I said, I am a particle physicist and I dont find these explanations convincing. I have an alternate way of viewing this concept and that has to do with Lorentz violation.

It is usually said that virtual particles are allowed to exist for a short interval given by the uncertainty principle. This indicates that Lorentz violation might be allowed in the Universe for time scales given by the uncertainty principle! My claim is not based on whim because I have shown in one of my published papers that certain Lorentz violating operators are enhanced in condensed matter physics. This also  indicates that we might be missing something in particle physics.

We should be open to the possibility of enhancement of Lorentz violation in particle physics as well. I am not saying that this is a correct claim, what I am saying is that how would we know that Lorentz violation is not possible if we havent even checked the implications of its presence in particle physics!

[1] See video on Virual Particles in the particle physics course on coursera

https://www.coursera.org/learn/particle-physics/lecture/zvi2t/1-2c-virtual-particles-optional

Lorentz Symmetry: A Sacred Relic for Physicists.

You might be wondering why the use of words like "sacred" and "relic" in the title. I did this because physicists are obsessed with this symmetry. Yes that's right, violating this symmetry can mean an end to your career in physics. This symmetry has a religious following in physics, as I usually say, especially in the particle physics community. Any paper that dares to talk about violation of this symmetry is considered sacrilegious and typically ignored by the community. You can only talk about this idea if the operators you are discussing are too suppressed to show any observable effects.

During my grad school life, I remember going to a conference on Lorentz violation. I had the pleasure of meeting one of the pioneers of the Standard Model Extension (SME). The SME encompasses operators that violate Lorentz invariance, but, again the coefficients are highly suppressed. One of the moments in the workshops that I cannot forget was when he expressed his frustration over how biased the physics community is about Lorentz symmetry. One of the examples he gave was regarding CPT violation. He said that the community is fine with CPT violation however there is a seminal paper by Greenberg (2002) proving that CPT violation implies Lorentz violation, which is strictly ignored by the community.

Now wait, I am not saying that this symmetry is not important, it is, but in my view no idea should be sacred in physics to this extent. Another example I can give you is from contemporary condensed matter physics which is filled with operators that violate Lorentz symmetry. In one of my published papers I have shown that a Lorentz violated operator from the SME is significantly enhanced in condensed matter physics. In another paper, which I did not even try to publish for obvious reasons described above, I gave examples of different operators in condensed matter physics where enhanced Lorentz violating operators are being used.

Any physicist knows that Einstein's theory was formulated in the vacuum and condensed matter physics is not about the vacuum. I always imagine what would happen if I transform an electron from the vacuum to a condensed matter system where the properties of the electron typically change. Not only that properties of photons typically change as well and light typically slows down in materials. There are a wide range of effects that are being observed in contemporary condensed matter physics. But, physicist will never mention Lorentz violation in all of this because they dont want to loose their jobs or they are too old to be innovative.

Another example I can give is entanglement in quantum mechanics. It appears obvious to me that entanglement is a form of superluminal transfer of information. Prof. Michio Kaku says that entanglement can be considered as a transfer of information thats not useful. This again demonstrates how biased physicists are when it comes to information transfer at superluminal speeds since it will implies violation of Lorentz invariance. On one hand there is a lot of research being done on storing information in spin while on the other hand particle physicists keep on emphasizing that this useful information cannot be transferred using spins. 

Physicists have stopped thinking about things philosophically. Moreover, well known physicists have said terrible things about philosophy. But I think that one of the reasons progress in physics have stopped is because physicists have stopped thinking philosophically. I want to refer every physicist, especially the young physicists, to an article by Don Howard. In it he discusses the philosophical mindset of Einstein. I will end this article by quoting Einstein where he warns us to strictly adhere to established ideas:

"Concepts that have proven useful in ordering things easily achieve such authority over us that we forget their earthly origins and accept them as unalterable givens. Thus they come to be stamped as “necessities of thought,” “a priori givens,” etc. The path of scientific progress is often made impassable for a long time by such errors. Therefore it is by no means an idle game if we become practiced in analyzing long-held commonplace concepts and showing the circumstances on which their justification and usefulness depend, and how they have grown up, individually, out of the givens of experience. Thus their excessive authority will be broken. They will be removed if they cannot be properly legitimated, corrected if their correlation with given things be far too superfluous, or replaced if a new system can be established that we prefer for whatever reason." 



[1] CPT Violation Implies Violation of Lorentz Invariance, Greenberg, O. W.

[2] The Joy Of Condensed Matter Physics, Inna Vishik.

[3] Albert Einstein as a Philosopher of Science, Don Howard.

[4] Understanding Lorentz violation with Rashba interaction, M. Adeel Ajaib.

[5] Lorentz violation and Condensed Matter Systems, M. Adeel Ajaib.

[6] https://www.youtube.com/watch?time_continue=124&v=QErwOK3S5IE