Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Questions about quantum fields

  1. Apr 13, 2014 #1
    Sorry if this is not a very we'll written thread. I have already had to re-write this three times because of computer problems. I have cut out almost all of the text I had previously written and moved straight on to the main questions I have. Please be considerate of my young age, which is fourteen, and correct any misinterpretations.


    1:Are quantum fields proven, false, or still a theory?

    2:What are these fields comprised of?

    3:Are all anti-particles also from a field? If so, do they have their own fields or do they originate from the fields of their counterparts?

    4:Is there any way to prove or disprove the existence of these fields?

    Thank you in advance for all answers and I'm sorry If this thread is not up to the slandered post for this site. If you see any mistakes please correct them. Thank you again.
  2. jcsd
  3. Apr 14, 2014 #2


    User Avatar
    Science Advisor
    Gold Member

    Do you understand what a field is? For example, an electromagnetic field?

    "Field theory" is a mathematical technique. Maxwell's electrodynamic equations are written in terms of electric and magnetic fields. We generally consider these equations to be correct ... they give correct predictions, and can even be quantized.

    When you quantize a classical field theory you end up with a quantum field theory. These also give correct predictions.

    You might find this interesting: http://en.wikipedia.org/wiki/History_of_Maxwell's_equations
  4. Apr 14, 2014 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The idea that theories can be categorized as "proven, false, or still a theory" is a major misconception that a lot of people have about science. In most sciences, a theory is a falsifiable explanation of a fact. For example, evolution is a fact, and the theory of evolution is what explains it. A theory in this sense can be falsified by facts that the explanation says are extremely unlikely to be facts. In the case of evolution, "rabbit fossils in the precambrian" is an often quoted example of such a thing.

    In physics, a theory is something that makes predictions about results of experiments. You don't prove or disprove a theory. You just find out how accurate its predictions are. A theory is considered good if its predictions are accurate, and bad if its predictions are inaccurate. Newton's theory of gravity is good. Einstein's is better. If I had to classify theories as "right" or "wrong", I would say that they're all wrong, because there's no theory that agrees with all experiments.

    No matter how many experiments have been performed or how accurately they have matched the predictions, the thing that makes the predictions is still called a theory. There are no perfect theories, and there is no word for a very good imperfect theory. So phrases like "still a theory" or (even worse) "just a theory" don't make sense.

    If you're thinking that a "law" is a proven theory, think again. A law is just a small part of a theory that can be expressed in the form of an equation or a brief statement.

    None of the quantum field theories contains an answer to that. In these theories, the fields are just special kinds of mathematical functions.

    Ouch, you made me realize that I don't remember QFT well enough to be sure of the answer, but I'll give it a try. In the case of electrons and positrons, there are two fields (mathematically related so that one can be calculated from the other), but it's not an electron field and a positron field. Each of these fields has relevance to both electrons and positrons.

    All you can do is find out how accurate the theory's predictions are.
  5. Apr 14, 2014 #4
    Thanks for the information. It was very helpful.
  6. Apr 14, 2014 #5


    User Avatar
    Science Advisor

    It's worth noting that some of the predictions of quantum field theory (in particular, quantum electrodynamics) are fantastically accurate. In fact they are the most accurate scientific predictions ever made, and they are confirmed by experiment. See http://en.wikipedia.org/wiki/Precision_tests_of_QED
  7. Apr 16, 2014 #6
    A proven theory: much like the theory of evolution, the germ theory of disease, etc.

    The fields are observables in the quantum theoretical sense. They measure the number density of field quanta per momentum eigenstate.

    Electrons and positrons, for example, are described by the same field.

    As mentioned in a previous post, QED (the prototypical quantum field theory) is the single most accurate theory in the history of science.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook