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B Can the theory change over time

  1. Oct 17, 2016 #1
    i and me teacher was in debate vs each other my teacher say we shouldn't believe in big bag because it is just a theory and it may change i say to him the theory is a collection of fact and model that have been on test then he say to me i have a B.S in physics do you know more than me .
     
  2. jcsd
  3. Oct 17, 2016 #2
    Quantum mechanics is just a theory. Classical mechanics is just a theory. Classical electrodynamics is just a theory. Does it mean we shouldn't "belive" in them? Ask him that.
     
  4. Oct 17, 2016 #3
    he say it may change i don't believe in big bang and evolution
     
  5. Oct 17, 2016 #4
    am going to ask him
     
  6. Oct 17, 2016 #5

    russ_watters

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    If you are quoting him accurately, he'said a physicist who apparently doesn't accept the concept of "science".
     
  7. Oct 17, 2016 #6
    Of course theories change over time. There's a lot of evidence for the Big Bang, but there are also a lot of things we don't know about the Big Bang, and things will change as we make better measurements or come up with new ideas. We probably have the basic outline of the Big Bang correct, but we are less sure about the early part of the Big Bang, particularly inflation. And we know we are wrong at the point when the Big Bang predicts a singularity.

    But if your teacher is a creationist, that's too bad.
     
  8. Oct 17, 2016 #7

    Fervent Freyja

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    You might get into trouble being so argumentative with your teacher. They don't like that very much. :wink:

    Theories aren't always backed up with experimental evidence. Sometimes, they are the best description available. Even if so, experimental evidence doesn't always offer a total description and so a theory may only reflect part of the whole picture. Definitions for concepts can always be improved upon- that doesn't mean prior theories were false.

    I would be careful with how you use the term 'fact', facts are things that don't and can't change over time.
     
  9. Oct 17, 2016 #8

    Nugatory

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  10. Oct 18, 2016 #9

    sophiecentaur

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    Your teacher's view that we shouldn't 'believe' a theory is actually quite reasonable. Science is not a matter of Faith and 'absolute belief' has no place in Science. All Science does is to produce a model of systems that is backed pu by experiment or observation. That's all that any Theory can do. If new evidence comes along, a theory that we accept now can be shown to be WRONG or, more likely, to need some extension to include a bigger range of conditions. Galileo and Newton were not Wrong, just because Einstein introduced SR and GR.
    The BB theory is verified by lots of observations but it is obviously not a complete model because it doesn't deal with the idea of what was 'before' the BB or what 'caused' it. That doesn't matter and one should never get too emotionally involved with that. BB is not a religion any more than any other part of Science.

    There are many 'Hypotheses' about the world that are not backed up by any serious observations and they are to be treated on that basis. String Theory is really more of a hypotheses (no measurements involved) - but it has a redeeming feature in that it tries to be self-consistent.
     
  11. Oct 18, 2016 #10
    The danger in these discussions is to equate the theory with "reality". Sometimes, our theories are actuallyexact descriptions of reality. But as a general rule they are not, they are just "reasonable" approximations. The point of science however is to find ever more accurate theories.
     
  12. Oct 18, 2016 #11
    At a certain point we should probably accept scientific theories and move on. It would take some serious work to convince me that the Earth is flat. Believe it or not people still do try to spread "Flat Earth" theory.

    The big bang theory is a really good theory. It explains much of what we can observe. I would be curious what your teacher would say if we asked her to explain the red shift that Hubble observed. What alternative to BB could explain it? The onus should be on your teacher. Saying that BB is just a theory doesn't dismiss it at all. Your teacher has a great deal of work to do in explaining all the evidence for expansion.
     
  13. Oct 19, 2016 #12

    sophiecentaur

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    I liked your post but I have to take issue with that statement. It is not necessary (harmful, even) to subscribe to an "absolute reality". The 'reality' in your post should, imo, be replaced with a 'near enough reality' idea. Reality, as with time, position, Energy etc. is an entity that applies over a limited range of situations. Your reality is not my reality and definitely not the reality of a photon.
     
  14. Oct 19, 2016 #13
    Following the logic of:
    Premise 1: if P then Q
    Premise 2: not Q
    Conclusion (modus tollens): not P

    We can make predictive models through the process of elimination, and thus leaving the theories we can't falsify. If we can't falsify them, we will use them in our practical applications, as they proved themselves to describe the results. There are also many times we have to use abductance rather than inductance, which would be extraction of a law based on observation, providing the model, and if it suggests something else through our maths, we then can start trying to falsify it.
    No, no theory can be thought of as the absolute fact, and anyone who says that is strawmaning science. A theory by its nature is a descriptive model, based on facts, which would be data points. For instance, F=ma, absolutely brilliant equation to describe motion in our day to day life. In quantum mechanics it gives us a slap in the face because of how energy works at those scales, and thus rendering newton's second law obsolete for those scales.

    Over time theories change, yes, but that does not mean that just because they are not absolute truths we should not at least entertain the idea. As an extreme example Gravity is just a theory right? By this logic I would not fall off of the cliff if I pass the edge. Except I would. Gravity is a phenomenon, and its theory is a description of its behavior.
    The big bang is what happens when you apply all of our knowledge into one messy equation. Should be said, the theory of the big bang predicted how the microwave background radiation should look like...Lumpy and relatively cold. We can no longer falsify an expansion, but it could very well be that the universe acted in a much different way at those times, at least before what and when the CMB shows, than what we currently describe.

    That's the beauty of science, it evolves constantly, to make up new theories or change current ones. It is the strength of the scientific method.
     
  15. Oct 19, 2016 #14
    "Reality" is of course very loaded term, and it can mean very different things. I was using the term very narrowly to mean the invariant aspect of the universe that everybody could agree on at any time, from any viewpoint. So, while things like energy can be observer-dependent, usually some kind of transformation exists that relates one's "reality" to another. A "correct" theory would be one that describes observations accurately for all of those.
     
  16. Oct 19, 2016 #15
    I can not imagine a Teacher that does not accept the BB theory teaching anything correctly about any subject that is a consequence of the BB theory.
     
  17. Oct 19, 2016 #16

    DaveC426913

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    It's hard to tell from the OP's paraphrasing. We don't know what the context is.

    It's entirely possible that the teacher is trying to guide him to the notion that even the most trusted theories should not be taken as Gospel.
     
  18. Oct 20, 2016 #17

    Svein

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    Anybody remember:
    • The Ether?
    • Phlogiston?
    • Earth, Water, Air and Fire?
     
  19. Oct 20, 2016 #18

    sophiecentaur

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    That's a response that I would expect from a 'well balanced' Scientist. However, most of the population treat 'reality' as an absolute, towards which Science is constantly moving. They (and their children) feel the need for absolute truths and to be able to rely on a system (or entity) that is responsible for such truths. That, imo, is the reason for the establishment of Religions.
     
  20. Oct 20, 2016 #19

    russ_watters

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    No...I wasn't alive then.

    I'm not exactly sure what your point was with that, but there is an Insight article around here somwhere (probably written by @ZapperZ ) about what it means for a scientific theory to be "wrong".

    It is fair to say that every theory scientists have ever had has been "wrong" or may end up being wrong. But don't misunderstand the confidence level difference between saying, Newton's theory/model of gravity is "wrong" and General Relativity might be "wrong". Not everything that is "wrong" is equally wrong. Newton's theory/model of gravity was far superior to anything that came before it. Despite the fact that it was suspected (and later proven) to be "wrong" hundreds of years ago, it is still used today because it still works pretty well, depsite being wrong. Similarly, if General Relativity is "wrong", it must be much, much less wrong than even Newton's theory/model. And rest assured, people will still be using it hundreds of years from now.

    The Big Bang theory/model has a number of known flaws, gaps and limitations, but it can't possibly be more wrong than "it's turtles all the way down". Many of the key elemets basically have to be correct.

    Hopefully the OP's teacher understands this and was just being argumentative as an exercise, because "shouldn't believe in the Big Bang" and "just a theory" are both trigger warnings for creationist crackpots.
     
    Last edited: Oct 20, 2016
  21. Oct 20, 2016 #20

    DaveC426913

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    I was too young to be there, but I've got their Greatest Hits albums.
     
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