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Physics vs Other Sciences

  1. Oct 11, 2012 #1

    these last days i've been thinking about the following question - "is physics the hardest subject since it deals with the most basic phenomena? which in turn are the basis of everything else?"

    In fact i just cant get a concrete example of something in another science that could make it more difficult than physics. How can the clustering of matter create something more difficult to deal with than the most basic particles and laws? Aren't these clusters of matter governed by the same laws that govern the atomic level?

    I am a computer scientist, and i know it is classified as an exact science like maths, so i wont try to compare it to physics since it is governed by its own "theoretical" laws, despite the medium in which they are implemented (digital computer, mechanical computers or whatsoever).

    But i think about chemistry and biology, can they be more difficult than physics while using structures composed by the basic particles that physics studies?

    Also is it correct to say that macroscopic objects are governed by laws that are more complex that the basic laws that govern their composing particles? Lets say, can i say that a human cell is governed (at the cellular level) by laws that are more complex than the ones that govern an electron or an atom? If that's the case then maybe i could convince myself that biology is more complex than atomic physics.

    Can someone give me some insight on this?

    Thanks in advance
  2. jcsd
  3. Oct 11, 2012 #2
  4. Oct 11, 2012 #3
    Personally, I feel that physics and mathematics are the easiest of all sciences. Let me try to explain. When you deal with "soft" sciences, such as psychology, then you'll find out that it is immensely hard to find a basic law or result. Psychology deals with human interactions, which are immensely complex.

    Physics on the other hand, deals with much simpler situations. And we know a lot of fundamental laws such as Newton's laws. The reason that physics is so difficult now, is because we already know a lot of it.
  5. Oct 11, 2012 #4


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    Difficulty is relative; frame-dependent.
  6. Oct 11, 2012 #5
    At the same time, physics is difficult because you must be constrained to whatever the design of nature happens to be - which is knowable through experiment. In physics there is most definitely a "right" answer to most questions - the one that agrees best with measurement.

    Mathematicians don't have that constraint, they're free to live in whatever dream world pleases them (although within each of their worlds there exist right and wrong answers). In "soft" sciences, there are usually no clearly right or wrong answers to many questions, and most questions probably are meaningless to being with. People can get it completely wrong without anyone ever knowing the difference.

    To say psychology is more difficult than physics is really just an appeasement to our poor psychology friends who don't have much of a leg to stand on.
  7. Oct 11, 2012 #6
    Mathematics, biology, psychology, etc. are difficult for the same reasons. There is most certainly a right answer to psychological questions, it is simply hard to make a decisive experiment to decide on that answer.

    They are free to live in such a dream world, but most do not live in such a dream world. Most mathematicians do work on things that are applicable to the real world.

    That's the point. Psychologists do not have much basic laws to stand on simply because their field is much harder than hard sciences. I have no desire to appease to psychologists.
  8. Oct 11, 2012 #7
    You usually don't know something is hard until you try it, and find out why it is hard.

    It is not the field, it is the way it is taught. Soft sciences are taught in a soft way. They're taught anti-quantitatively.

    Also chemistry is hard because it has to actually work in the constraints of real world phenomena (not just physical laws but what actually happens in the real world which is a much tighter constraint). Designing a cancer medication or material for an OLED display is extremely difficult, for example.
  9. Oct 11, 2012 #8
    This idea that everything could be best understood by breaking it down to physics hasn’t gotten past even the first hurdle of explain all of chemistry with quantum mechanics. Sure, quantum chemistry has had some massive advances over the years, but it’s nowhere near close to becoming a pet of physics. This type of question always bugs me in that it seems to imply that if rather than having 1000 biologists and 1000 physicists doing research, we just had 2000 physicists doing the research that we’d somehow know more about biology because physicists are so much “smarter” or more capable” than biologists.
    The fact is that choices in which sciences to go into aren’t made by the “I’m not smart enough to go into physics so I’ll go into chemistry” or “I’m not smart enough to go into chemistry so I’ll go into biology” etc, but by what the person’s interests are.
    Agreed. It’s much easier to isolate a particular effect in physics and chemistry research than in biology/psychology etc. Note that the closer you get to a truly “natural” system (an atom in a magneto-optical trip is perfectly isolated but about as far from “natural” as you can get) the more complicating factors there are and the less definitive the predictions can be in terms of breadth and reproducibility.
    To make a generalization that the reverse is true is just a value judgment about what sorts of answers deserve more respect and is likely just ego stroking for people who happen to like studying isolated physical systems rather than more open and complex ones.

    I don’t buy that for most questions of psychology you’ll get a “right answer” that isn’t probabilistic and perfectly reproducible (the way, say, a vibrational spectrum is in chemistry) for anything but the most basic questions. That’s not to say that it’s a lesser science, just that it’s not as easily isolated and constrained by comparatively simple laws the way the “hard” sciences are.

    This idea that all that the “soft sciences” need is to be more quantitative (“more like physics” is perhaps closer to what is meant) to be more successful has a built in elitism to it that bothers me. Why or why don’t these silly psychologists just learn math and get the right answers? Why they must not be as smart as us “hard scientists” who do all of this math and get definitive answers all day long.
    “Soft sciences” are “soft” because the answers that you’re able to get aren’t nearly as definitive as what you’re able to get in the “harder” sciences where you can hammer things into not probabilistic answers. This is a limitation due to the complexity of the system, not in the scientists doing the work. Take Einstein and von Neuman and Dirac and force them to be psychologists and they’re not going to come up with anything more quantitatively definite than anyone else.
  10. Oct 11, 2012 #9
    I've only really taken beginning level biology, chemistry, and physics, but from that point of view, physics is by far the most difficult. I don't see how you could even argue against that, at least at the beginning class levels. And I don't see why that would change as you take more difficult classes.
  11. Oct 11, 2012 #10
    Research is vastly different from learning in classes. In classes, there are correct answers to every question on every assignment and test. Not so with research.
  12. Oct 11, 2012 #11
    What is considered hard is, as someone said, "relative". But that is used strictly in an academic setting, when it comes to research, most things become hard. Whether one is harder than the other is a matter of perception.

    But to my last point made above, the comparison is wrong in my opinion. Why would you be comparing what is harder? That seems to be a misguiding notion of what science is, which is to explain, not be used by someone with a certain agenda to make one-self feel better.

    In most cases this is basic psychology, you group people by shirt color, all of a sudden certain groups of colors will think they are better. Group people by race, all of a sudden people will start believing they are superior. Group people by profession, all of a sudden they believe their profession matters most to the world.

  13. Oct 11, 2012 #12
    Quoted for truth.
  14. Oct 11, 2012 #13
    I thank you all for yours comments. I did not intend to offend any of the mentioned sciences, its precisely the opposite, i believe that they can all be difficult but i would like to understand well what makes so. I've seen comments stating that chemistry is hard because it has to deal with higher level restrictions, mostly impacts that some substances would have in our bodies, even though in the simply physical level they would be precisely the solution to eliminate the problem. Also biology is hard because we have to "reverse-engineer" what nature created, in order to understand it, and that may not be trivial.

    Yet i wonder about the following: chemists made lots of models regarding molecules, atoms, more complex molecules and such, but the thing is, wouldn't these models be much more accurate if they could be explained using only particle physics terms? I believe that when we abstract something, say, accepting that atoms exist and their inner level interactions don't matter, we are losing some precision because atoms may in fact suffer from phenomena related to their inner composition (quarks and so). So isn't a chemist who works at the atomic level in fact losing some precision?

    But this brings me the question, does abstraction actually makes things easier? Can the abstracted layer have its own challenges that can be as much, or even more difficult than the ones of the lower layer?

    For instance, can it be that chemistry challenges regarding molecules and connecting them, and manipulating them and so, be more difficult than the challenges posed by the subatomic particles layer? Or the challenges posed by biology, by manipulating genes, antibodies, understanding which antibodies to use against certain viruses (all this abstracting the molecular level as we are taking it for granted) be more difficult than chemical or physical challenges?

    Is the behavior of a atom that is composed by subatomic particles, more complex than the one of the subatomic particles? Can the behavior of molecules which are composed by atoms be more complex than the behaviour of atoms? Can the behavior of a cell, which is composed by molecules, be more complex than the behavior of molecules?

    At least to the last one i would say yes, but i'm not an expert in physics or chemistry, what do you think?
  15. Oct 11, 2012 #14
    The process that you’re talking about is called “reductionism”. In principal some believe that you should be able to reduce all chemistry to quantum mechanics to relativistic quantum mechanics to particle physics etc. There are some aspects of quantum chemistry that require explicit relativistic effects to be accounted for (transition metals, for example) but generally it adds nothing to the accuracy of the calculation for most systems but adds an unnecessary layer of complexity (and hence computer time and effort). For interactions of a small numbers of atoms and molecules, quantum chemistry can explain some things, but for anything but tiny systems a large number of approximations must be made to make the calculations tractable. For huge numbers of relevant systems, only portions of systems can be treated with any quantum mechanical accuracy and the rest need to be treated as classical particles.
    Past these systems though, there are those who are interested in researching systems where such reduction isn’t only not practical but not possible EVEN IN PRINCIPLE. This field is called “emergent phenomena” and examines effects that can’t be decomposed into the sum of the parts.

    Of course it does. In order to check your email, would it be easier to think about what’s going on with the transistors, the logic circuits, the bits, the machine language, the higher level language, the html code etc etc etc, or is it easier to just operate at the level of “open a window and click”? Knowing what’s going on at the level of the transistors doesn’t help the experience of writing and email easier or better, so why think about it when writing?
    Some things are “harder” than others, but it has nothing to do with what field of research you think the work fits under. As I said in a previous post, it’s not as if we’d answer all the questions in biology and psychology if only we could draft physicists to research them. That’s a prejudiced way of thinking based on a value judgment of what sorts of answers you find satisfying: The definite and reproducible results common to physics or the more open ended and probabilistic results of the “soft” sciences.
  16. Oct 12, 2012 #15


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    Difficulty is entirely dependent on the person doing the work, the scale of what they are attempting and the tools they have. As there is no objective measure of difficulty you can directly compare two fields.

    When I did my MSc the class was from a mix o backgrounds; engineers, chemists, surgeons, physicists and biologists. We all found areas outside of our own expertise difficult at first and had to study to catch up. I never got a sense that the physicists had it any easier studying biology than the engineers.

    The problem with the idea that fundamentals must be harder because they explain the rest in theory is that in practice it's not like that at all.
  17. Oct 12, 2012 #16
    I thank you a lot for your answer, it has clarified me about two things: the abstraction that chemistry has about quantum physics, and the conclusion that abstraction indeed makes things easier.

    But about how hard subjects are, can you ask the following question: can chemistry be somehow harder than physics, concerning each one at their respective level of abstraction?

    I know that chemistry involves more particles, and hence will be more difficult than physics if trated at the particles layer of abstraction, but what about Chemistry at molecular level VS Physics at particles level. Could chemistry be harder? Or Biology at the celular level?

    I'm trying to understand how difficulty behaves as we go up the abstraction layer. Psycology seems harder since i consider humans to be more complex than a atom (at least from what i know), but im not sure about smaller things.
  18. Oct 12, 2012 #17
    Sure. Chemistry is insanely hard at even the diatomics stage. Give me an analytic model of bonding in anything more complicated than H2+ (yes, that's 2 protons and a single electron)? You can't. Even adding a single extra electron to make a hydrogen molecule makes the problem analytically intractable.

    The problem is that diatomics suck. They're boring and not so useful in terms of industrial production. So we have to do complicated molecules and solids. That's a problem.

    That's not counting emergent phenomena when you have N particles near each other. You get things called energy bands because the discrete energy levels are perturbed a tiny bit by nearby atoms, and when you add up N of them (where N is on the order of 10^23) there are no longer discrete energy levels but rather energy bands separated by bandgaps. it is the existence of the bandgap, and how we can control the bandgap with chemical modification of solids, that gives rise to solid state electronics. You can't derive that. Just like there's no way you can derive the Navier-Stokes equations from quantum chromodynamics.

    Also, in computational chemistry, anything bigger than about 1000 amu is treated classically. Any collection of molecules is treated classically. You know how polymers or proteins are simulated? Balls and sticks that are labeled "hydrophobic" or "hydrophilic". Why is it done this way? 1.) it saves loads of CPU time and 2.) when we simulate polymers we do not care about the electrons, but instead we care about chain dynamics. This allows us to see emergent phenomena that we can't at the quantum chemistry level - protein folding, solvation and phase separation.

    Lest you think this is a cheap undergrad trick - its a technique taught in grad level statistical thermodynamics called molecular mechanics, and it is a very useful computational tool to simulate complicated systems.
  19. Oct 12, 2012 #18
    the problem is that physics and chemistry also look at open and complex systems ie simulating diffusion-reaction in a time release capsule, engineering implanted biosensors, designing new methodology for electron microscopy or radio telescopes, and stuff like that. Since these devices actually have to work, they're firmly grounded in the real world.

    psychology is indeed becoming more quantitative. mathematical behavioral sciences is more and more important by the day. this is a natural trend because computers are more and more avaliable and makes gain/effort ratios much higher for quantitative research than non-quantitative research.

    and it is true that while biologists still dominate biology, more and more physicists, chemists, chemical engineers and related disciplines are moving towards biology. that's because some problems in biology cannot be solved with the tools given to traditional biologists.
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