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

+/- Duality?

  1. Feb 10, 2007 #1
    Can we, in principle, consider electrons as positive charges and protons as negative charges? How would our laws change if that was the case?

    Do you guys think that the convention of choosing electrons as negative charges and protons as positive changes was a mistake?

    Do we really need the concept of plus and minus? Can't we just get along fine with "bill" and "bob"? For example, two bills will repel each other and a bill and a bob would attract each other?

    Also, is it possible to eliminate the concept of plus/minus from physics? Just like we eliminated negative temperatures (in the Celcius scale) by creating a new scale (the Kelvin scale) that only had positive temperatures.
    Last edited: Feb 10, 2007
  2. jcsd
  3. Feb 10, 2007 #2


    User Avatar
    Gold Member

    Well we cant, at least not now say that electrons are positive, becuase it is decided to call its charge negative. Could we have called an electron positive? Of course! "Positive" and "negative" are simply names to describe two phenomena.
    The rule is that for atoms to exist, the nucleus and the "shells" must have opposite signs, thats all. We could say that nucleus could me made of anti-protons (instead of protons) and the shells could have positrons instead of electrons - its the same principle.
  4. Feb 10, 2007 #3
    Well, it isn't quite as simple. A little before the time of J. J. Thompson, the discoverer of the electron, electrons was a phenomena known as cathode rays. The cathode is the negative electrode from which the electrons originate, suggesting that the +/- was in use even before the official discovery of electrons. It was even in use at the time of Benjamin Franklin, although unfortunately he chose to call "positive" the charge opposite that carried by the usual charge carriers.

  5. Feb 10, 2007 #4
    We could theoretically call them positive or negative. We could call them yin and yang if we want, alpha and omega, we could even call them simon and garfunkel.
  6. Feb 10, 2007 #5
    Sure, the laws would be slightly simpler, since electrons would flow in the direction of conventional current.
    It was a fair mistake. They had a 50% chance of guessing correctly, and their choice was established long before any experiment existed to determine which part really actually formed the current.
    Sure, the names are arbitrary, but the mathematics is not (note two bills and a bob is the same as one bill).
    No, because there isn't a bound on charge (in either direction), and because there is a great physical significance to neutrality (like absolute zero, unlike zero Celsius). Moreover, the concepts of addition and subtraction are fundamental to physics, and just clumsy without the concept of negative numbers.
  7. Feb 10, 2007 #6
    What exactly do you mean?
  8. Feb 10, 2007 #7
    The signs were given just for identification of the charges. But the names had to be such that we could also do some math on the subject. That is why, + & -. Now, since it is one of the fundamental theories of physics, we cannot swap + & -, as then we will require a change(though slight)in all the other theories(more particularly, the formulas).

    Note: If I have gone wrong somewhere, please correct me.
  9. Feb 11, 2007 #8
    When you start applying it to force and other equations, i you get a negative answer then you know its an attractive force, if its a positive answer its a repulsive force. Yes, calling electrons negative and protons positive is arbitrary, but they need to be positive and negative, not one unit or the other.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: +/- Duality?
  1. Fel and Fg interaction (Replies: 3)

  2. Vacuum Comsol (Replies: 1)