So in the last two posts I was talking about how experimental and theoretical physicists may complement each other, and how the future of physics and science as a whole may be doomed if we leave everything at the ends of lobbyists and legislators. But then it occured to me that we don’t really know how many kinds of physicists are there. This is an oversimplified version of many colleges, and universities curricula in way to properly say what the consensus for different types of physicists.
Now there are many ways to answer that. First, we need to go with conventions We start by answering at a more fundamental level, you have two types of physicists, fundamental physicists and applied physicists. What is the main difference between the two? Arguably the same as a theoretical mathematician and applied mathematician. Which means, that while both applied and theoretical physicists can work on the same subject, an applied physicist would work on a subject in order to find a pratical use out of it. Now while this seems similar to engineering, it is not exactly the same thing, since an applied physicist will most likely be doing research on the physics of some thing, and later may find some use for it. A good example would be physicists Lauterbur and Mansfield, which applied the physics of nuclear spin and magnetic resonance to medical imaging, completely revolutionizing the field. On the same note, a fundamental physicist would also be researching the physics behind some particular phenomena, while not being particularly interested in the use it may have, they would doing research just for the sake of knowledge and physics. Using spin again, a good example would be physicists Bloch and Purcell, which found a mathematical model that could describe the behavior of nuclei under magnetic fields, and the phenomena of magnetic resonance that would occur.
When 80 years of work and anything between 7 to 9 Nobel Prizes, from Physics to Physiology & Medicine, led to this wonder of a machine.
Besides of fundamental physics and applied physics, you may divide physics in two other (maybe three) types of physicists. You have the theoretical physicist, the experimental physicist, and while many believe a computational physicist to be a theoretical physicist, some argue that it may be a type of its own. A theoretical physicist would as the name implies either develop mathematical models to describe phenomena that were observed experimentally, or to predict outcomes that will be observed experimentally (nowadays it is mostly the latter, technology is lagging behind), while the experimentalist usually would try to verify results predicted by the theoretician, or just would do a random experiment and see what happens. (Before, most physicists were both experimentalists and theoreticians, but today most physicists like to dedicate to one thing or the other) Also, experimentalists would also work on ways to make the observations more reliable or statistically significant, or to be able to make experiments in different, or more extreme conditions. Sometimes, developments on experimental physics will be applied by applied physicists in other fields (like how they are now using the detector tech developed to detect the Higgs boson in other fields like nuclear medicine or in telecommunications). A computational physicist would pretty much run simulations of the theories in computers to try and see what the results could be. Now this is important, because nowadays physical experiments are expensive, so instead of doing experiments everytime we come up with a new hypothesis, we run simulations on computers. If the simulations are good, or what we expected, cool, if not, we have to change something. While this may seem something that a theoretician would do, and many do, a computational physicist would be working on various other things. They could, for instance, work on computational methods that allow for better, faster simulations, and those things are hard to do. Believe me. And that is why many are now believing that computational physics is a type of physics distinct of pure theoretical physics. (And also applied physicists may also be computational or experimental physicists just saying).
And the day-to-day life of a computational physicist, in that moment the code finally compiles, after 3 full bottles of coffee and 6 hours.
Now the part everyone cares about, the divisions of fields in physics. Truth be told, it is very hard for a single person to be working on various fields at the same time nowadays, so it became important to make distinction between those fields.
First, we have Nuclear and Particle Physics, which is like the poster child of modern physics (I mean, literally every person thinks that a modern physicist is either a particle physicist or astrophysicist). And they usually worry with the fundamental forces and constituents of nature. It was started with the discovery of the nucleus by Rutherford or with the discovery of radioactivity by Becquerel, about a 100 years, and right now, it is the field where such hot topics like the Higgs Boson, Supersymmetry, quantum gravity, GUT and string theory are extensively researched. On the applied field, there is a surprisingly high number of applications of Nuclear Physics, like the entire field of Medical Imaging and Radiotherapy, being pretty much Applied Nuclear Physics (with knowledge of physiology and anatomy), and let’s not forget Nuclear Energy, and Nuclear Bombs. As for particle physics, I don’t think we will have an application for it so soon.
We also have Condensed Matter Physics, that studies condensed matter (like liquids and solids, and everything in between) and their physical properties. They study things like phase transitions and distributions of energy and states, something statistical physics, I guess. And they apply various fields of both classical and modern physics, like quantum mechanics. This field overlaps with others like Chemistry, and Biophysics (an applied physics) and has some cool things to be studied like superfluidity and superconductivity, and topological phase transitions. Usually the field is subdivided in Solid State Matter Physics and Soft Matter Physics. Now, while Physics doesn’t have a industry of its own (like the Chemical Industry) you can say that arguably, the most important field of Modern Physics to industry is CMPhysics, specially SSMatter Physics, because all of modern electronics is based on research in CMP. So, you can imagine that the applications usually involve nanotechnology, semiconductors, and oddly enough, or maybe not, even MRI (which kind of makes sense, thanks to superconductivity)
Am I forgetting something…
Right, we still have atomic and molecular physics and astrophysics and classical physics, that while not being a research for physicists anymore, are still very researched in engineering and mathematics, because of the so-called chaos theory. Right now, I will stop right here, but I will complete this latter. I am feeling lazy right now, sorry AMPhysicists and Astrophysicists, but don’t worry, your turn will come.
EDIT: So now, I am supposed to finish this, huh? Oh boy!
So, we also have AMO Physicists, which stand for Atomic, Molecular and Optical Physics. And their name is kind of self-explanatory, but I will make an effort. They are usually worried with interaction between matter and light, or just matter-matter, or even light-light (I don’t know, the possibilities are enormous). And they are also divided in (you guessed it) Atomic physics, Molecular physics and Optical Physics. Atomic physics is concerned with studying the physics of a system composed of electrons and a nucleus. While it may seem they do the same thing as nuclear physicists, that’s hardly the case. They usually are concerned with the system of electrons and the nucleus and their interactions, while nuclear physicists usually deal with atomic nuclei and their properties, disregarding their interaction with electron for most fundamental models. As for molecular physics, it is less about the inner workings of atoms, and more with how molecules interact with each other. As you can imagine by that, there are fields like physical or theoretical chemistry which are concerned with pretty much the same thing, so they hang out together a lot. Optical Physics is primarily studying light. The nature of light, the behaviour of light, the interactions of light with itself, interactions of light with matter, it’s all tied to light. Now when I say light, I mean electromagnetic radiation, they study all the electromagnetic spectrum, not just visible light.
Now let’s go to the sexiest physicists out there. Astrophysicists! If I didn’t put them down here, probably the guys would just read this part and leave without caring for the rest. Now astrophysicists are just worried about one thing: The nature of heavenly bodies and the physics (and chemistry) behind all astronomical events. That is their “thing”. Astrophysicists are usually seen (or maybe I am the one who seems them like that) as one of the two extremes in physics, dealing with the physics of the very large, while particle physics deal with the physics of the very small. And considering the scale and variety of things to work on, obviously it also has subdivisions. I mean, you have Planetary Physics, with Geophysics specifically focused on Earth, that studies planets and their physical properties, including extrasolar planets. You have Solar Physics that studies the heavenly bodies in the Solar System and their interaction, studying things like the motion of bodies inside of the solar system, which is not easy because you have a multiple body system where all those bodies interact with each other and generate their own gravitational field. You have Stellar Physics that study the physics of stars, like star formation, stellar activity and stellar death, the Heliophysics specifically studying the Sun. They also study things like Black holes and Neutron Stars. (I don’t know if you realised but the trend is to keep getting bigger in scale) You have galactic physics that studies the physics of well galaxies, how stars interact with each other inside a galaxy, how a galaxy forms, what is the physics behind galaxy conformation, and other questions. You even have extragalactic physics, that study interactions between galaxies, the distribution of galaxies in a group, and extragalactic bodies, like quasars or pulsars. And finally the crown jewel, Cosmology that studies the fundamental and cooler stuff in astrophysicist (from a pop science POV). They study the entire universe, its evolution, its beginnings, and its possible end. Also they study the nature of spacetime, like the existence or not of wormholes, multiple universes, Dark Matter, Dark Energy and Gravitational Waves (There are definitely some Metal bands with at least one of these names). As for applications, there are way too many, and this article is getting way too long.
Uh, no, no images for astrophysics, I mean, the wallpaper for this site is a literal galaxy. And I am not even an astrophysicist, I am doing plenty of favor to them.
The main thing you need to know is that physics is very diverse, and you could do things that would change the world, but most important of all, no matter how hard you may think of it, physics is something you should do only if you like it enough. If you are willing to work on the same problem, sometimes for decades, just to get that one confirmation of a fundamental truth. You may not win a Nobel, but damn, you would feel joy in working on this amazing field. Scientia Prima as some would say.
Also, just leave a comment below or anything, so I can have a feedback from you guys, I don’t want to talk to a wall.