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B Is Special Relativity Universally Accepted?

  1. Jan 2, 2018 #21

    bhobba

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    I know exactly what you meant and personally would not have worried about it. But the OP is a beginner, and as one of my professors once said (he was the schools no 1 expert in analysis) you have your best professors teach the foundation subjects. The reason being getting things not quite exact at the start can do irreparable damage. More experienced students you don't have to be as careful with and using language like you did that was not quite precise is OK - in fact its done all the time - the people concerned know what you mean. Its just wise with 'newbies' to be more concise.

    Don't worry about it - just keep in the back of your mind a bit of care with those less experienced is needed.

    Thanks
    Bill
     
  2. Jan 2, 2018 #22

    Mister T

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    There were a lot of textbooks written after that that used the concept of relativistic mass, usually claiming that Einstein's 1905 theory predicted it and experiments confirmed it. It wasn't until the 1990's that those claims began to disappear. In the 1994 edition of Halliday and Resnick it wasn't even mentioned!
     
  3. Jan 2, 2018 #23

    vanhees71

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    Well, there's a quite recent textbook in German (Rebhan, Theoretische Physik: Relativitätstheorie und Kosmologie) which all in all is quite good, but he insists on the relativstic mass :-((. He mentions that he was heavily critizised in a book review concerning this point, but he insists on the didactical value of the notion of relativistic mass. I can only disagree with him in this point, but as I said, that's however only one weak point (and favoring the Bohm interpretation of QM in the quantum-mechanics volume is another, although he does this also only in a separate chapter) of otherwise a very good theoretical-physics-book series.
     
  4. Jan 2, 2018 #24
    That's just plain wrong. CERN wouldn't work if this were true.

    Where did they say they got the PhD from? Trump University?

    The old "trust me, I'm an expert in this," is the telltale lie of the bullshitter.
     
  5. Jan 2, 2018 #25

    mfb

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    Born 1937. You know the saying how some things stop being used...
     
  6. Jan 3, 2018 #26
    Wow, thanks to all for such an informative set of answers. You have all very kindly provided lots of extra reading into the history and validity of SR which is exactly what I wanted. I can't thank you all enough and I will definitely read over all the extra links/info provided. I have never come across crack pot scientists yet I can't quite get over how angry they made me feel. They were saying that professors know SR is wrong but they don't tell their students this otherwise they would have to scrap most of modern physics as it is based on SR like we are all leading some kind of lie in the science community. The reason it angered me so much is it doesn't matter how ugly the world is, science is always there as a saviour as it unites nations (regardless of political conflict) in an effort to explore the universe and advance our race. This is what I love about science. Maybe I was naive but I didn't think anyone on the planet could ever try and bring it into such awful disrepute. I almost think it is like trying to bring a charity into disrepute. They say it as though science is some belief system based on Einstein that we could never deviate from. As far as I am concerned if people did know it was wrong and had conclusive evidence they would become instantly famous. Science would never progress if it held onto incorrect theories on purpose. I understand some governments may be corrupt and there are benefits to them being corrupt but there is no benefit to corrupting science (not that I can see anyway). Again, I get why people may be suspicious of some governments because it is a fact of history that many governments have been and still are corrupt. But why the suspicion over science which has no history of corruption? If SR was wrong I don't see a SINGLE benefit to the science community in covering it up and holding onto it. In fact I see nothing but disadvantages. This is why I can't even understand the motive to do this in the first place.

    Anyway sorry for going on too much. Newjerseyrunner could you explain your last post. I was under the impression this nut job was wrong because he doesn't even understand the current theory of SR. He said that Einstein (and SR) said that as you approach the speed of light your mass goes up. His "evidence" for SR being wrong is that particle accelerators observe no mass increase. As I understand it his "evidence" actually makes SR correct because SR (and Einstein) never said mass increases as you approach the speed of light. So particle accelerators should show no mass increase. Is what I said correct? Thanks again.
     
  7. Jan 3, 2018 #27

    PeterDonis

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    I can't say what's going on in the nutjob's head, but, as I said in post #5, I think the basic confusion he is illustrating is failing to distinguish different possible meanings of the term "mass".

    SR and Einstein never said rest mass increases as you approach the speed of light; they have always said that rest mass is an invariant and doesn't change as speed changes. But as I said in post #5, in the early days of SR, the term "mass" could also be used to mean something called "relativistic mass" (which in modern terms is just the object's total energy in a particular frame, in mass units), and that does increase as speed increases (because total energy increases as speed increases); and Einstein knew that perfectly well.

    Particle accelerators show no rest mass increase. And since the term "mass" is pretty much exclusively used to mean rest mass now, "no mass increase" means "no rest mass increase". But the energy of particles in accelerators certainly does increase, exactly as SR predicts, as the speed of the particles increases--in fact "speed" is not even measured in accelerators, energy is the key parameter, so much so that particle physicists routinely report even rest masses in energy units, for example when they say the Higgs boson mass is 125 GeV (that's giga-electron volts, an energy unit).
     
  8. Jan 3, 2018 #28

    PeterDonis

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    Unfortunately there are plenty of such people, many of whom even call themselves scientists and claim (and might even believe) that they are doing it "for the good of science".

    Unfortunately, if science and scientific findings are used as political tools, there can be a benefit--politically--to corrupting science. A historical example is Lysenkoist agriculture in the Soviet Union. But this is getting off topic; if there is a place at PF for a discussion of something like this, it's most likely the General Discussion forum.
     
  9. Jan 3, 2018 #29
    To expand on what I said about CERN. It’s particle accelerators work by creating an electromagnetic pulse that gives the projectiles a little push. These pulses have to be synced up so that they push the particles at exactly the right time, so you have to be able to calculate where they are going to be.

    As you approach relativistic speeds (well within the capabilities of CERN) those pushes give each particle less speed because it’s harder to push. This has to be accounted for and is. If it wasn’t, the beam and the pulses would be out of sync.


    To address professors knowing SR is wrong: sort of? They know it’s a special case of general relativity: as in it doesn’t work in the real world because it doesn’t allow for acceleration. But teaching it is a required step to understand general relativity. Teachers teach Newtonian physics first, and that’s not necessarily wrong, just incomplete. If you want to be technical, GR still is incomplete and everyone knows that. People tend to cherry pick specific flaws in a theory in order to try and throw out the whole thing and that’s not how science works.
     
  10. Jan 3, 2018 #30

    jbriggs444

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    Special relativity handles most forces and the associated accelerations just fine. What it does not get right is gravitation as a force causing an acceleration.
     
  11. Jan 4, 2018 #30

    zonde

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    I would like provide a viewpoint from a bit different perspective in addition to valid and informative things others have said in this thread.
    There is possible reason why such crack pots show up and keep spreading nonsense. The reason as I see it is that SR often comes with a bit of philosophy. That bit of philosophy is that inertial reference frames are fundamentally equivalent. That piece of philosophy is unacceptable for some (including me). But there are two things about it:
    1. Even if you reject that, let me rather call it - interpretation, you still get the exactly the same physics. There is a term for this approach - Lorentz Relativity.
    2. If people are incapable to separate interpretation from actual physics they might start to attack the physics because they wrongly perceive that actual physics depend on that interpretation while it does not.

    I hope my explanation can help you reduce your emotions and help you defend physics better if you ever need to.
     
  12. Jan 4, 2018 #31
  13. Jan 4, 2018 #32
    Oops, something went wrong, #31 was meant as a reply to #30.
     
  14. Jan 4, 2018 #33

    zonde

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  15. Jan 4, 2018 #34
    "How do you experimentally test the difference between fundamental equivalence and non fundamental equivalence?"

    Equivalent just means that you cannot distinguish whether you are on the one or on the other, as an observer: you will find exactly the same laws of physics. This holds for all inertial reference frames. That's why the equivalence is physics and not philosophy. Does that answer your question? (P.S. I do not know what you mean by fundamentally equivalent, I would say equivalent is equivalent).
     
  16. Jan 4, 2018 #35

    PeterDonis

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    Please provide a mainstream reference--textbook or peer-reviewed paper--that makes this claim. Otherwise it is not SR, it is just your personal opinion.
     
  17. Jan 4, 2018 #36

    PeterDonis

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    Which is off topic per the PF rules.
     
  18. Jan 4, 2018 #37

    vanhees71

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    Well, you can calculate the trajectories of particles without ever using the idea of a speed-dependent mass. These are relics of the very early years of SR, and you don't need relativistic masses anymore to precisely calculate relativistic trajectories, and indeed LHC wouldn't work if you'd not use precise relativsitic analysis.
     
  19. Jan 4, 2018 #38

    zonde

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    Of course it's not SR, that was what I claimed.
    Ok, maybe I was not clear enough so let me reformulate the statement: SR often comes with a bit of philosophy that is not part of SR.
    And here are references:
    Bell,J.S.(1987).How to teach special relativity. Speakable and Unspeakable in quantum mechanics:papers on quantum philosophy. CUP, Cambridge
    Special Relativity from the Dynamical Viewpoint
    This is arxiv publication, but it contains references to relevant textbooks: On the Lorentzian route to Relativity
     
  20. Jan 4, 2018 #39

    mfb

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    This is simply a case for Occam’s razor. You can use special relativity. Or you can use a framework that makes exactly the same predictions as special relativity but has to add various elements that are not observable and make the mathematics more complicated. It’s like working with special relativity but additionally assuming the existence of an invisible unicorn without any interactions. The unicorn doesn’t change anything but you still include it in every statement you make.
     
  21. Jan 4, 2018 #40

    vanhees71

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    It's ridiculous to claim the teaching of outdated ideas as pedagogical. Lorentz's route to relativity with his insistence on the existence of an aether even after Einstein's breakthrough is really outdated and should be taught in lectures on the history of science (which should be offered to interested students far more than is the case) but not in physics lectures. Here the Einsteinian point of view is the most clear and convincing way accepted by the majority of physicists.
     
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