Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I want to believe that it is true!

  1. Dec 14, 2006 #1
    It seems to me that it is very hard for scientists to be really impartial. I would love to believe that relativity is 'true'. It would be a great convenience. I am still a bit of a doubting Thomas at heart. I would like to be able to go on a plane with my own atomic clock and compare the times found with my earth bound one after I've made a return trip to Thailand from Riyadh. I'd like to be able to do the maths to make the prediction as well.

    Now most of that does now seem almost within reach. My prediction is that the clocks' times and my mathematically predicted times would be in very close agreement - whatever that means! At least the effect, time dilation would be observable.

    Now to those who are already comfortably in the know - that might seem like a big so what? It isn't quite that though.

    We see the evidence we want to see. Why is it that the world happens to be this way? It is extraordinary. But that is the point isn't it? The world is an extraordinary place!

    I like to show my students simple transformers. Holding two coils roughly wound on U - shaped laminated cores and then putting them together and suddenly the light bulb lights up. I have to spen some time to really convince them that there is nothing in terms of actual bare cables joining the two coils. A small piece of cling film between the two cores usually does the trick. That is pure magic to me. It is the real world in front of us.

    And now I can see something of the simple way (or not so) via Maxwell's equations it leads to ideas about time and space and the motion of the planets and stars - wow - how unified.

    I found a chap called Paul Hewitt. He's been teaching physics in Haiwai for umpteen years and videos his lectures. Mostly he keeps the maths out of it and just tries to demonstrate the physical concepts. Inevitably there is some maths in it but my students who are much younger than the one's he is teaching love it.

    I saw a couple of nights ago one of his videos on relativity. He approached the twin paradox using the dopler shift. I couldn't get it the first time I watched it because I was too bogged down with trying to make mental Lorentz transformations from one frame to the next. Now I think that I am beginning to catch on to how simple it really is.

    The very fact that to understand the doppler shift for light is so much easier than to understand the doppler shift for sound - well that just appeals to my own lazy sensibilities. But it is true that many mathematicians will say that the essence of the best maths is that it is simple - like good old E = mc^2


  2. jcsd
  3. Dec 14, 2006 #2
    Make an experiment.Don't trust any theory.He,he,he.
  4. Dec 14, 2006 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2018 Award

    No we don't!

    As an experimentalist, I can tell you with zero doubt that your statement is wrong. There were MANY things that I wished I had seen, and I didn't! There were many things that I didn't expect to see that I have!

    Fleshman and Pons wanted others to evidence for cold fusion. They didn't find it, and neither did anyone else. There are many other predictions that never materialized, no matter how much those people wanted to see them. Millikan never wanted to see the evidence that Einstein predicted for the photoelectric effect behavior, because he was convinced that Einstein was wrong. His whole purpose at setting up the experiment was to show that the Einstein model was wrong. Yet, he ended up showing one of the most convincing evidence that the Einstein mode was valid.

    So no. While we may be biased towards something, there is no way to fake or willed a physical evidence that will be tested by others. It is why we publish our work so that others can verify what we observed. Somehow, the reproducibility of such observations seems to have escaped your evaluation here.

  5. Dec 14, 2006 #4


    User Avatar
    Gold Member

    Einstein's SR is one of the most rigorously tested theories in the history of science, and it has passed with flying colours every time. I think you would be astonished at how much of today's consumer-grade technology would simply not work at all if SR was not accurate.

    Perhaps, if I could read between the lines, what you want to ask is this:

    Can anyone supply some high school lab demos I could perform to demonstrate SR as applied to the real world?

    Let's see.
    GPS receivers account for SR.
    Um, you could do the "cheese slices in a microwave" experiment (not really SR, but demonstrates the speed of light).

    Any others?
  6. Dec 14, 2006 #5
    It already is, with GPS as DaveC426913 said. Or you could wait until the next eclipse.
  7. Dec 14, 2006 #6
    I should have qualified my bit of rambling by saying that we 'sometimes' see the evidence we want to see. But there was another bit of philosophical musing going on there which has to do with a lot of what we see we only see because we deliberately go looking for it.

    There was something else in this rambling which has to do with the fact that as a child I was never 'taught' relativity in school, and it is still not on the under 16 curriculum. That potentially sends out a potent message to young people -well the message could be many things - like we don't think the teachers can be trusted to teach this stuff, or we think that you kids are not bright enough yet to deal with it, or it is only a half baked theory that we are not sure of yet. Don't get me wrong - I am not an anti-relativity crackpot! I am expressing the feelings of doubt that have been instilled in me by my stupid British education!

    To give you another example; when I was in a grammar school in the late 70's we were taught that atoms 'might' be real; and that no one had as such made any firm observations of any yet!

    It seems to me that if it is safe to tell children that the world is round and that the Sun is at the centre of our solar system, that we live in a galaxy with probably over a hundred billion stars in a universe which we believe has as many billions of galaxies as there are stars in our own milky way, that it should be OK to tell the kids that at very very high speeds time slows down, and not that we just believe this to be the case - that it has been as people have said - and the evidence is there - that it has been tested rigorously time and time again.

    What we are told to teach is that light travels in straight lines! What does that really achieve? No wonder there is so much confusion in the world! Instead of teaching kids that light travels in straight lines, why not start with another simple rule: that there is an apparent speed limit in the universe -

    I do long for the day when it will be a simple matter of habit that people can get on planes and find out that their incredibly accurate nano-second watches really do run slower. The nearest I have seen is when they did a repeat experiment with a couple of atomic clocks during one of the Faraday Christmas lectures I saw on the beeb about fifteen years ago.

    I found out the it was Horizon who repeated the Hafele Keating experiment in 1996. The programme was sold to PBS Nova but I don't seem to be able to see it in their catalogue of DVD's - a pity - it would be nice to have something really tangible to show the kids. Any suggestions?
  8. Dec 14, 2006 #7


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2018 Award

    Well, your "rambling" is very puzzling. You want Special Relativity to be "taught" to kids in school as if the concept is so transparent that it is understandable. It is not. Furthermore, you can't just shove something out there dangling in mid-air without any foundation to base it on. This is why we get crackpots using quantum mechanics for everything imaginable - because they seem to think the various phenomena associated with quantum mechanics just came out of nowhere without rigorious mathematical foundation and derivation. So to thrust special relativity to kids who still cannot understand why there is no "centrifugal force", yet they can "feel" it everytime they go around a bend, would be introducing something before they have the framework to comprehend what they're told.

    Besides, how many times have you tried to reason with a child to stop doing something, and he/she went right out and did it again? You expect SR to be taught rationally at this level?

    Again, if you are under the impression that everything that we know should be understandable to you, or worse still, to kids who still do not have a foundation on the basic principle of physics, then there is something wrong with your logic. It is as if no effort should be put in to understand such a thing, and that it should all fall down right onto your lap for your consumption. Most of us who accept the validity of such a thing put years of effort to learn it. I can also easily tell you that SR is the LEAST strange of the stuff we deal with today. Wait till you find out the stranger stuff that is going on in your modern electronics!

  9. Dec 14, 2006 #8


    User Avatar
    Gold Member

    And how!

    SR is a walk in the park compared to QM.

    • "Quantum mechanics is magic." Daniel Greenberger.
    • "Everything we call real is made of things that cannot be regarded as real." Niels Bohr.
    • "Those who are not shocked when they first come across quantum theory cannot possibly have understood it." Niels Bohr.
    • "If you are not completely confused by quantum mechanics, you do not understand it." John Wheeler.
    • "It is safe to say that nobody understands quantum mechanics." Richard Feynman.
    • "If [quantum theory] is correct, it signifies the end of physics as a science." Albert Einstein.
    • "I do not like [quantum mechanics], and I am sorry I ever had anything to do with it." Erwin Schrödinger.
    • "Quantum mechanics makes absolutely no sense." Roger Penrose.
    Last edited: Dec 14, 2006
  10. Dec 14, 2006 #9


    User Avatar

    Staff: Mentor

    No, you're really missing the point: you aren't taught differential equations in high school either and the reason isn't because teachers can't be trusted with it, it is because it is quite simply beyond the capacity of high school students.

    There is a lot out there to learn, and you can't take it out of order.
    Yikes! You must have gone to a crappy school, because scientists needed to be pretty sure atoms existed when they started splitting them 30 years earlier.
  11. Dec 15, 2006 #10
    I too am a skeptic and I embrace my doubts. Here is a quote from Feynman's "The Meaning of It All"

    In practical terms, all those particle accelerators surely do support Einstein over Newton over and over again, every day. But they don't prove Einstein, they only disprove Newton. And even this, at the philosophical level, must be in doubt. On your physics quiz, go with Einstein. In your heart, doubt everything.
    Last edited: Dec 15, 2006
  12. Dec 15, 2006 #11
    I first learnt about relativity from a very simple TV documentary. That was how I was introduced to the ideas. Because it was a TV documentary there was no mathematical proof of how time dilation or length contraction occurs and yet I found what was presented very convincing and easy to follow.

    To try to 'proove' from first principles that the world is round or about details of the planets orbits would be far beyond any young person's mathematical skills. We don't need to proove these things becuase they can be shown fairly simply e.g. by photographs of the Earth taken from space. Likewise to simply 'tell' someone that time does actually slow down when you travel at very high speeds is not a difficult thing to do - especially if you have video footage of experiments like the Hafele and Keating to refer to, or if you can refer very simply to things like GPS.

    I introduced the ideas of relativity to a class of pre-GCSE students last year. It was only one of the briefest of introductions because of the time permitted. A couple of days later one of the weakest students in the class came up to me and told me that as a result of hearing these exciting ideas she had decided to take an A level in physics. She also went on to get an A grade in her exam.

    If one only teaches Newtonian mechanics to the young developing mind, one inevitably teaches youngesters to see physics as Newton did and open and closed case of a mechanical universe with everything predeteremined. They get the sort of idea that was presented to Stephen Hawking when he was a phd student, when he was told that there wasn't much point in doing physics because it had essentially all already been worked out.

    What has made physics exciting to me if the discovery that we have not reached a final picture of the universe and that this is a period of time, as indeed was the whole of the last century, when there is the potential for new things to be found out. That makes it a far more exciting adventure. Therefore I will continue from time to time to tell my students about quantum mechanics and relativity and even to show them Mr Greenes videos about super strings because it excites their imaginations and gets them thinking.
  13. Dec 15, 2006 #12


    User Avatar
    Gold Member

    Yes. It gives me goosebumps to think that we are on the edge of a new frontier in understanding our universe.
  14. Jul 15, 2010 #13


    User Avatar
    Gold Member

    Sorry to jump on this detail, I know it doesn't represent the gist of what you're talking about.

    The thing is: in a low-math exposition, why would anyone approach the Twin scenario using the doppler shift? Sure, if you do the math then the doppler shift approach will yield the same numerical result as the other approaches do. However, for an introduction to SR the doppler shift approach is the least suitable one.

    A good exposition homes in on the precise aspect of where relativistic physics is different from newtonian dynamics. The doppler shift approach conflates two independent aspects: transmission delays and relativistic effects, thus obscuring the picture. So for anyone to use the Doppler shift approach in a low-math exposition of SR makes no sense at all. With such an approach the audience will be wrongfooted. That is my opinion: the Doppler shift approach does not expose SR, it hides SR.

    My favorite relativistic scenario is one that is usually referred to as http://en.wikipedia.org/wiki/Bell%27s_spaceship_paradox" [Broken]. In his article 'How to teach special relativity' Bell recounts how at one time he had a dispute with a fellow physicist about a particular SR setup. To help settle the case they canvassed some members of the CERN theory division. Interestingly, a majority got it wrong at first, changing to the correct answer later, on further reflection. Of course Bell's spaceship paradox is unsuitable for including in a first introduction to SR, but I do feel that a good introduction should not hide how deeply unsettling SR is.
    Last edited by a moderator: May 4, 2017
  15. Jul 15, 2010 #14


    User Avatar

    Staff: Mentor

    This thread is 4 years old.
  16. Jul 15, 2010 #15


    User Avatar
    Gold Member


    The thread surfaced in a Google search, with google labeling its date as 'last post Yesterday'.

    I've made this mistake before; I should have paid attention to the date on the thread page. Something triggers Google into labeling years old threads as recent threads.
  17. Jul 15, 2010 #16


    User Avatar

    Staff: Mentor

    A spammer somehow picked this thread to post to, a couple of days ago, and Google found that post before we found it and deleted it. :frown:
  18. Jul 15, 2010 #17


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    He just wants to believe it's true too
  19. Jul 15, 2010 #18
    Someone PLEASE give some more detail about what this is!

    Physicists figured out how everything in the universe works a long time ago. They just pretend they don't know so they can stay employed and have excuses to build big toys like the LHC.
  20. Jul 15, 2010 #19


    User Avatar
    Gold Member

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook