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Reality Scorecard for Physics Theories

  1. Jan 10, 2014 #1
    After reading Lee Smolin's Time Reborn and Rodney Brook's Fields of Color, a question occurred to me. Has anyone compiled a "reality" scorecard for the differing theories out there, both current and historical? For example, QFT proponents would consider the following things as real:

    1. fields
    2. field quanta
    3. causality
    4. 3D universe

    And, Lee Smolin and like minded people would consider time, causality, events, etc. as real in contrast to most physicists.

    It is not my desire or intent to start a discussion about what "reality" is or to argue whether a particular theory is correct in what it posits as real. Rather, I was wondering if there was a summary some place taking each physicist or school at his/their word about what is real or unreal. It just seems like an interesting perspective even for those physicists who think such questions are outside physics or who may think that we don't have access to reality. For those physicist, laws and mathematics seem to take on the role of "reality". So, a little bit of detective work would be needed in those cases.

    So far, I have compiled the following list of historical and current "things" that physicist have considered real. If anyone wants to make additional suggestions, that would also be appreciated.

    Ether, particle, wave, particle-wave, string, force, field, field quantum, quantum, 1D time, 3D space, spacetime, >3D space, >1D time, event, causality, law, probability, mathematics, energy, universe, and multiverse
     
  2. jcsd
  3. Jan 10, 2014 #2
    Unless there is a definitive definition of what is "real" , the list would be controversial.
     
  4. Jan 10, 2014 #3
    I dont believe there is such a definitive definition. What is "real" or not doesn't matter to any theory in science. In my opinion and experience, debate over what is "real" or not is a matter of opinion, philosophy and religion - not science. Science is about modeling observations.
     
  5. Jan 10, 2014 #4

    Vanadium 50

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    If you want "real", go read The Velveteen Rabbit.

    Physics is about models, and matching them to observations. Different models have different elements in them and different ranges of validity.
     
  6. Jan 10, 2014 #5
    And that is what is so fascinating about physics. Physicist are able to present new theories and posit new physical entities without a hard and fast definition of reality. It is almost as if our brains have a hard-wired notion of reality that allows us to understand the world. There are those who would argue that at some point (if not already) our brains will be incapable of understanding the world. I am not in that camp since it would make science pointless. But that is outside the scope of my original question.

    Just for background, the driving force behind my original question was whether we have sufficient "real" things to support the next revolution in physics or whether some genius somewhere will add to the list to bring about the revolution. As interesting as a discussion as that would be, that is also outside "scope".

    I just thought it would be revealing to have a list or compile a list of real things and to see how each theory picks and chooses from the list no matter how controversial. I have already taken a first stab at the table, but I was wondering if anyone knows of such a list. Can't know where you are going unless you know where you are and where you have been.
     
  7. Jan 10, 2014 #6

    Student100

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    If our brains were hard wired to understand the actual physics of the world than why are so many physical phenomena counter intuitive? It just isn’t so. Math, reason, logic, and everything else in that line of thinking have a place in physics, but nature is the final conciliator.

    Observation is what makes physics a science and establishes a range of validity and uncertainty within models. Physics has never been overly concerned with the why, or unlocking the hidden mechanism behind various parts of nature. Nothing in physics can be considered as “real” or "this is why" nature behaves the way she does. We can approximate what should happen within a certain model, and we can do that quite well.
     
    Last edited: Jan 10, 2014
  8. Jan 10, 2014 #7
    While I agree with these statements, I don't think it's really fair to completely reject the OP's question on those grounds. We just might have to rephrase it slightly to avoid saying that physics necessarily claims anything about reality.

    Physics doesn't make claims about what's real and what isn't, but I would argue that it's still quite useful to imagine that our physical models are "real" when we're trying to make predictions with a model. When solving a classical mechanics problem, I imagine a world where "reality" follows classical mechanics. When solving a quantum mechanics problem, I imagine a world where "reality" obeys the laws of quantum mechanics. Obviously, both worlds can't be "real," but it's still helpful to imagine them as "real" when solving a problem.

    That's the whole point of conceptual problem solving, isn't it? We pick an appropriate model and we construct an imaginary world in which that model is perfectly true and real, and then we imagine what would happen in such a world. Though we know that imaginary world doesn't necessarily reflect reality, we also know that the outcomes in that world will (hopefully) be similar to the outcomes in reality. So it's at least useful to pretend that world is real for the purpose of making predictions.

    A rephrased version of the OP's question might be "what do we imagine to be real when we solve a problem using a given model?" For the classical electromagnetics model, the list might include charged particles, electric fields, and magnetic fields. I think that's pretty much what the OP is looking for, and such a list isn't based on philosophical grounds, it's based on what we, in practise, treat as "real" to solve a problem within the context of that model.
     
  9. Jan 10, 2014 #8
    ^^ With this perspective, every aspect of every scientific theory is "real" and real is just a label for that which is contained in a scientific theory.

    There is no need to treat anything as real vs unreal to solve a problem within the context of a model. Its an idea that is completely superfluous to scientific theory.
     
  10. Jan 10, 2014 #9
    Thank you for your reply. I am sorry, but you misunderstood what I was saying. I was not saying that our brains are a microcosm of the world and that is why we can understand it. I am saying that our brains are set up to identify objects and to correlate those objects into models.

    It sounds like you are in the school that limits those objects and models to mathematical ones for physics. There is a place for that philosophy in the table that I am looking for or trying to construct. My goal is to construct an all embracing overview without judging each model. Perhaps I shouldn't call it a "reality" scorecard since "reality" seems to be a trigger word. However, any other word I have tried, just doesn't do it. For example, an "object" or "element" scorecard lack the punch although they are more neutral. I am open to suggestions.
     
  11. Jan 10, 2014 #10

    Dale

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  12. Jan 10, 2014 #11
    I'm not saying that models define reality, I'm saying that it's tough to use a model without also coming up with a mental image in which you treat that model as if it were real.

    Take classical electromagnetics as an example. Sure, in principle, you could refuse to assign any meaning to the symbols E, B, ρ, and J since they're not directly observable. You could just grind through the math and refuse to create any sort of mental picture, but who actually does physics like that? As far as I know, most people will create a mental image of the problem in which E, B, ρ, and J are treated as if they're real. When you do that, you're not saying that any of those things must actually be real, you're just imagining them to be real to solve the problem.

    I can imagine a world in which unicorns exist without claiming that unicorns actually exist. The world I imagine when I solve an electroamgnetics problem is really just as imaginary as the unicorn world, the only difference is that my imaginary electromagnetics world actually helps me make useful predictions about reality.

    So I still don't understand why we can't answer the OP's question. What entities and qualities exist in the mental images we create when solving a problem using classical electromagnetics? What about when we use quantum mechanics? To me, it seems that this is really a question about the nature of the conceptual models we use, and not a question about what's real and what isn't.

    What if someone were to ask for a list of things that are "real" in the Harry Potter series? (magic, wands, dragons, etc.) You wouldn't refuse to answer that question on the grounds that J.K. Rowling's intention wasn't to describe reality...
     
  13. Jan 10, 2014 #12
    Thank you for saying more eloquently what was I was fumbling to say. It is my own personal bias that the next big revolution in physics will be a mechanical model that explains the mathematical models physics has discovered over the past 100 years. However, opinion and bias should never be the deciding factors for scientific "approximations" (although they are usually the motivators for exploring a potential solution). I always find the motivations behind a particular theory or model interesting. Great pains are taken to remove as much of the human element as possible, but taken in context each is a statement proclaiming to the world "See, I told you so!"

    Beyond the educational value of the scorecard for myself, the hope in constructing the table is to show myself or another an interesting combination of elements not thought of before or to highlight a missing element that when added will make sense of all the other elements.
     
  14. Jan 10, 2014 #13
  15. Jan 10, 2014 #14
    If I could show you (off-line) a simple mechanical model that could explain for example quantum mechanics, would you be willing to reconsider your position that physics should not be concerned with unlocking the why or the hidden mechanism. The point I want to make is not that one particular mechanical model is currently correct or available, but that mechanical models can have a place alongside mathematical models in physics. We might have to adjust our basic assumptions about the universe to do it, but it is possible.
     
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