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How do we deal with theories that are hard to prove or falsify?

  1. Nov 23, 2009 #1
    Hi, In this other thread https://www.physicsforums.com/showthread.php?t=354424" I was hoping to get a scientific answer to my question. Apparently this was not an easy question or hypothesis that was easily falsified. I was sorry to see the subject turned into a unpleasant debate which ended up in a locked thread. Although I think Calnoth could be right it is disappointing to see such an idea is so easily marked as a crackpot idea, just because it's so hard to prove and so opposite to other theories that remain unproven?

    I was just about to suggest the idea of making a computer model to get a better visual view of this theory. For this I would need to get a lot more information first of course, I'm not sure if I can get enough to create a realistic model. Since the topic was locked maybe I could create a new topic on this?

    I would like to raise one more question. Last week I received two PMs from an apparently blocked user, entitled "the simple truth". He claims on this forum lately some messages went missing, people being banned and even whole threads got deleted, because of censoring. I don't know what he's talking about. Maybe these where also about theories that are hard to prove and inconsistent with other unproved but accepted theories? Like I mentioned in the other thread those scientists where 'desperately' asking for new crazy theories because their current ones eventually let them down. Is it so hard to be open minded about new theories although they seem very unlikely?

    I just like to get an honest opinion. I don't mean to start another unpleasant debate.

    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Nov 23, 2009 #2
    New ideas always need to be carefully assessed. Unfortunately most people who promote them really don't have the training or experience to assess them properly against a given body of knowledge. For example, over the years different people have developed models of cosmological redshift which pose the idea that photons lose energy over distance and time. That might sound reasonable, but it is inconsistent with the observations of supernova which show the expect time dilation that a real redshift would explain but "tired light" does not. However that observational fact doesn't stop advocates of "infinite universe" theories from using 'tired light' as an explanation for red shift time and time again.

    In the end a good theory should produce observational results that can be compared against the predictions of alternative theories - the theory with the best fit or the easiest theory to adjust to new data is then the theory that is preferred. Often times a lot of professional jealousy powers the strong emotional outbursts from both sides - an observational fact, even if it isn't very 'scientific' - but emotion is best used by harnessing it to propel further research and effort, and inspire good critique. Rivallry between research groups ensures the flaws in both are exposed to clear-headed scrutiny.

    However there can be a level of dogmatism, powered by the emotional investment that is required to become professionally competent. Unfortunate, but it happens. To their credit most scientists are willing to entertain new ideas, but ideas that are presented with that certain mix of ignorance and arrogance get rejected without a thought. Nothing annoys good scientists more than slanderous cranks.
    Last edited by a moderator: Apr 24, 2017
  4. Nov 23, 2009 #3
    I guess you mean "infinitely old universe", because there is not one piece of evidence that would exclude spatially infinite universe. So, if one is considering infinite universe, it really has nothing to do with 'tired light'.
  5. Nov 23, 2009 #4


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    Hi Luuk, the only reason your hypothesis is apparently difficult to falsify is that it is 'not even wrong', that is to say, your post indicates that you have thoroughly misunderstood the basic premise what 'the universe is expanding' actually means, so your alternative solution is a solution to a problem that doesn't exist. I don't mean to be insulting, I know that's how it sounds, but that's just how your original post comes across. It doesn't mean you are silly, just that you haven't yet studied much physics, that fine though, there's no requirement to be an expert here, that's the whole point.

    The reason why PF doesn't encourage these kinds of discussions is not because it's part of a global conspiracy trying to suppress debate about physics, but because it is a forum intending for people to learn about physics, the physics we know and understand. There are other places for people who understand current theories to discuss ways to change or disprove them, here we want people to understand the current theories first, rather than idly speculating before understanding the status quo.

    There are also other places on the internet where people who have no idea about physics can go to idly speculate with each other, PF is not one of those places.

    My advice would be to ask some questions about the current theories, rather than asking questions about a speculative alternative. There are no questions too simple or too 'silly', just ask away. It's much easier to answer an question about some aspect of present theory, than have to debunk an alternative at the same time, so you'll get a much better response asking questions.
  6. Nov 23, 2009 #5
    That's ok Wallace. No offense taken. If I have misunderstood the expanding of the universe completely, can you tell me where exactly I can find a good explanation? You say the problem I was trying to solve does not exist, but that's not what the scientist that are studying the expansion say. But maybe I see the problem from the wrong point of view with a lack of proper understanding. I would like to study this more so if anyone could point me into the right direction that would be very much appreciated.

  7. Nov 26, 2009 #6
    Prof. Ned Wright's http://www.astro.ucla.edu/~wright/cosmolog.htm" [Broken] is a good place to start.
    Last edited by a moderator: May 4, 2017
  8. Nov 26, 2009 #7


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    Luuk your original idea was not so wacky, it just needed developing a bit.

    All measurements are a comparison of a physical quantity with a standard unit of measure, if we are taking about expansion in space then that unit of measure is the standard metre.

    Your question could be rephrased: " What if the universe is not really expanding, but instead the standard metre and rulers are decreasing in size. "

    Now in order to answer this question we have to decide what yardstick to choose as the standard unit and then measure everything else by that standard length unit.

    The 'standard' answer (pun intended!) was originally a metre rule constructed of platinum-iridium atoms, so the standard is actually the size of these atoms, and now the metre is defined as the length light travels in 1⁄299,792,458 of a second.

    However if the atom should gain mass then its diameter would shrink and atomic clocks would speed up, i.e. the standard ruler would shrink and the standard second would shorten, but note nevertheless the speed of light as measured by those rulers and clocks would not change.

    There are published heteordox theories, mass field theories, in which this happens, such as Fred Hoyle's paper "On the Origin of the microwave background" Ap.J. 196 pg661-670 1975. In this theory the universe is static and particle masses vary from place to place, the event we call the Big Bang is reinterpreted as the boundary between a positive particle mass universe and a negative one, on the boundary itself particle masses are zero and hence the atomic Bohr Radius is infinite.

    However there is no physical difference between an expanding universe with fixed rulers and a static universe with shrinking rulers, it just depends on what you define to be your standard invariant quantities. The 'standard' convention is to define particle (rest) masses to be invariant and rulers to be fixed. Hence, given Hubble red shift, it is understood that the universe is expanding as measured by those fixed rulers.

    Last edited: Nov 26, 2009
  9. Nov 30, 2009 #8
    It's impossible to prove a theory. As far as how to falsify a theory, if you come up with a theory, then it's up to you to come up with about a dozen ways that it can be falsified.

    Yes that's hard, which is why theoretical physics is much harder than it first seems. Deep down, all good theoretical physicists are crackpots, but they are *disciplined* crackpots.
  10. Dec 1, 2009 #9


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    A theory that cannot be falsified is little more than religion 101 until a definitive test is proposed.
  11. Dec 2, 2009 #10
    On the other hand, getting a theory to the point where it makes testable predictions is really hard.

    Mentioning religion brings up an interesting point. One of the first things that Medieval scholars did once they rediscovered the Greek classics was to attempt to mathematically and scientifically prove the existence of God. Now, today most people would say "but you can't mathematically and scientifically prove the existence of God" to which I'd reply "Have you tried?"

    And it turns out the reason people today think that the existence of God is unprovable is because people spent close to five hundred years trying to do it before giving up.

    One other thing that's interesting is that the notion that the essence of science is falsifiability is very, very recent. It was first formalized by Karl Popper in the *1920's* as part of the school of logical positivism. People in the 19th century didn't explicitly define science in that way (although you can argue that they *implicitly* were acting in that way).
  12. Dec 2, 2009 #11


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    The original question was a very good one.

    The answer is that the universe is not expanding on the scale of individual galaxies. So it is a misunderstanding of what the expanding universe means. The universe is expanding on a scale on which huge groups of galaxies are averaged over and the galaxies lose their individuality, and space is filled with a uniform fluid, and the question doesn't enter as to whether the points in this uniform fluid shrink or expand. Think about air. In everyday life, we don't know that air is made of atoms, and so when air expands, it is meaningless to ask whether the air molecules are also expanding or contracting. It turns out that on the scale of single galaxies, the universe is not expanding, and so the question doesn't come into play on that scale.
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