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Physics failing?

  1. Mar 16, 2006 #1
    Hello, I wish to start this, my first post, by saying that I am NOT trying to upset anyone, nor are my questions hoaxes.

    I'm no physicist either, I used to take physics in highschool, but since then, I have not pursued it further.

    My question is this... Is physics failsafe? Are its laws always constant?

    Allow me to use gravity as an example. According to my highschool books on the subject, gravity is based upon the attraction force between two objects. It is directly related to density (With greater densities exerting a greater gravitational force). But is that an absolute? If one were to put gravity to the test using the same object, well, let's go for Newton's apple. Had the situation been repeated over and over again, could there ever be a possibility that the apple would not fall?

    I know it sounds crazy, I'll admit, I was hesitate to post it for fear of being ridiculed, but well, from my understanding of science, it's very hard to have absolutes.

    Again, sorry if this came out as a hoax or something, I'm just looking for some proof. Thank you for your time.
  2. jcsd
  3. Mar 16, 2006 #2


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    Nothing in science is truly an absolute. Sure, we can do an experiment ten million times and get the same result every time -- but that doesn't mean we wouldn't get a different answer if we did it just one more time.

    Science is based on models, which are "made up" machinations that can be used to predict the results of experiments. When such a machine accurately predicts the results of every experiment ever done, we regard the machine as having value, and perhpas even being 'correct.' It is entirely possible, even likely, that some later experiment will come along (perhaps with advancing technology) that will show flaws or gaps in existing models.

    This vulnerability doesn't mean scientific models are irrelevant junk; they obviously still have great power. Many of the inventions which have improved human quality of life were created with the guidance of scientific models which were later shown to be incomplete.

    Science is an iterative process, something akin to trial-and-error on a grand scale. It's always becoming more refinded; sometimes in leaps and bounds, and sometimes through slow, steady progress.

    - Warren
  4. Mar 16, 2006 #3
    Thank you for your answer.
  5. Mar 16, 2006 #4


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    Anytime, Yahya. Welcome to PF. :smile:

    Don't feel intimidated by the "serious" nature of the site. Feel free to ask anything you'd like to ask.

    - Warren
  6. Mar 16, 2006 #5
    chroot said it very nicely :)
  7. Mar 16, 2006 #6


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    Wait, isn't it false to say that gravity is directly related to density? It's directly dependant on mass...
  8. Mar 16, 2006 #7
    Yes your right gravity has never been related to density past or present, but the validity of that statement had little to do with the question being asked. chroot did a fine job there.
  9. Mar 27, 2006 #8
    That is actually a very good question, David Hume asked himself much the same thing. The scientific meathod is a purely inductive process and as such, there is no proof, just probability.
  10. Mar 27, 2006 #9
    There's a lot of confusion among lay people about scientific terminology such as law and theory. A responsible scientist will always concede that nothing is absolute. However, when a physicist says something is a law, the average person can pretty much assume it is a certainty.

    You see this often when lay people dismiss global warming out of hand because it's "only a theory." Generally speaking, a theory means "our best explanation based on the what we know." That can range anywhere from "our wild guess" to "we're nearly 100% positive." The vast majority of journalists simply cannot grasp this concept, so there is a lot of confusion. Scientists must always leave things open-ended because the continued pursuit of knowledge is the simplest explanation of what a scientist does (and it makes for better job security that way).
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