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What is Fact?

  1. Apr 27, 2004 #1
    Hi I am new to physics, I am acctually an artist, comic book work mostly. This is all very interesting to me and I am inspired to paint or draw different aspects of this theory and physics in general. My problem is where to begin? What is fact? What is just theory? Are is anything proven at all? Thanks in advance.
  2. jcsd
  3. Apr 27, 2004 #2


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    Scientific theories are not proven. They are supported by experimental or observational evidence. But since we can never gather ALL the evidence, their acceptance is always provisional - well, we do know the earth is round!

    General relativity and quantum field theory, the two main branches of modern theoretical physics have both a lot, and awful lot, of supportive evidence. In spite of many attempts to overthrow them, they remain unfalsified.

    That word "falsified" comes from Popper, a philosopher. He said that that was what science had in place of mathematical proof, the fact that its theories could be falsified by even one experiment. Not everyone agrees with Popper all the way, but this is a good idea to put up against the idea that scientific theories have to be either true or false.

    The cutting edge fields which are the theme of this particular forum - string physics and quantum gravity, are so far unsupported with empirical evidence. This leads to futile arguments because the scientists don't have their usual standard to go by. The reason they don't make predictions that can be checked in the lab is that they both deal with very high energy states, and there is a limit to how much energy the human race will be able to generate and concentrate for at least the next few centuries, so no tests are really possible. Unless somebody thinks up something really clever...
  4. Apr 27, 2004 #3
    Actually, SA, we don't really know the Earth is round! What we think the Earth to be is due to the way in which it presents itself phenomenologically. But it can present itself in an infinite number of ways. The only possible way to know the true ontological nature of a transcendant object is to be omniscient. And even then, we still have to provide an answer that the object is what it presents itself to be.

    Kinda sucks, eh? ;)
  5. Apr 27, 2004 #4


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    successful theories can be used for something, normally

    a spherical model of the earth can be used for navigation and will
    help to get your flight into Ohare airport on time

    vintage 1925 (quantum) atomic theory can be used to calculate what color
    light some hydrogen gas will glow when it gets hot and it will be right
    or pretty close to right---you actually do see the calculated colors

    vintage 1915 gravity theory (Gen Rel) can be used to calculate how much
    some starlight will be bent as it passes by the sun and will turn out right
    or how much to correct the GPS satellite timesignal and it will turn out right so that the GPS gives correct positions

    vintage 1680 gravity theory can be used to predict planet motions and
    guide probes around in solar system and they get there

    electronic theory can be used to design a circuit or a component and it will ordinarily work OK


    where people seem to have trouble is with unfinished theories that dont predict any firm numbers yet (and may never do that---one cant know the future)

    some theories, still under development, simply dont predict any numbers
    so you cant check them against anything or test them or use them for
    any practical purpose

    some folks are reluctant to regard untested theory as
    in any sense "factual"

    but then they get into arguments about this with other people who have a fervent and passionate faith that "something like this must be right, we just have to perfect the details" and so on. Deeply held convictions and wishful thinking can seem to substitute for fact---even take the place of experimental evidence.


    so you are asking "What is fact" and one can give a practical or pragmatic answer that in the models used in physics and engineering and navigation etc. that fact has to do with testability and prediction and whether or not you can use it to get numbers that will check out
    and whether the earth is round enough that you actually get to chicago.
    Last edited: Apr 27, 2004
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