where does light from a torch go?

Discussion in 'Physics & Math' started by emanresU, Apr 13, 2014.

  1. origin Trump is the best argument against a democracy. Valued Senior Member

    Messages:
    9,823
    Russ of course is correct. The term light, photon and EM waves are different names for exactly the same thing.

    We can measure the speed of light. The speed of light (c) is used to define the meter. You are really going about this wrong. You clearly are not up to date on many, if not most, of the well understood aspects of physics. You should be asking questions instead of making statements.

    Here is a piece of advice. Someone who makes declarative statements that are clearly wrong is considered a fool. Someone who asks questions to increase their knowledge is considered wise.
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Read-Only Valued Senior Member

    Messages:
    10,296
    Quite correct. The ONLY thing he's doing here is exposing his GROSS ignorance.
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. origin Trump is the best argument against a democracy. Valued Senior Member

    Messages:
    9,823
    Sure, but the bottom line is not knowing something is fine, there is lots of things that we all are ignorant of (like ending a sentence with a preposition, which may or not be ok [idk]). Not knowing and pretending you do know or refusing to admit you are wrong, that stifles learning and is just plain foolish!
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. Russ_Watters Not a Trump supporter... Valued Senior Member

    Messages:
    5,051
    Agreed. People should be encouraged to be open about their ignorance. Ignorance is not a virtue or flaw in and of itself, but admitting and trying to overcome ignorance is a huge virtue. It is a critical component of maturity. Conversely, trying to hide or worse using ignorance for freedom to speculate is very wrong.
     
  8. Read-Only Valued Senior Member

    Messages:
    10,296
    Yes, I agree. HOWEVER, in this particular case, he strongly refuses to LEARN despite the fact that people have tried to explain some very, very simple things to him.This individual acts just like a 'flatlander' despite being shown pictures of Earth and the satellites circulating it.
     
  9. origin Trump is the best argument against a democracy. Valued Senior Member

    Messages:
    9,823
    True.
     
  10. dav57 Extraordinary Thinker Thingy Registered Senior Member

    Messages:
    621
    I don't have much time - you will probably be glad to hear - but I'm still thinking about all of this. I know i said that photons have a rest mass (and thanks for attacking me for that one) but from what I have read in recent years wave theory is very different to photon theory and although they compliment each other, photon theory can't describe the travelling wave characteristics and wave theory cannot give a good explanation of how photons interact. Which is what I've been saying - they are very different in behaviour. I can't see how you can just say a wave is the same as a photon. Also, apparently, photons DO have a non-zero mass when observed inside superconductors. Waves don't. So there must be a difference. We never see waves but we do see photons.

    I've also read (correct me if I'm wrong) that it would be impossible to construct any experiment that would establish a photon's rest mass was indeed exactly zero. I have read various contradictory claims on the subject and it's all very interesting. What I'm really trying to do is make a distinction here between a wave which i agree travels at c and thus has no mass and a photon which at the point of interaction must have reduced its speed to zero, so it's no longer a wave and could well have different properties, including mass.

    Is that possible?
     
  11. exchemist Valued Senior Member

    Messages:
    6,297
    What do you mean by "wave theory" and "photon theory"? This seems to be a false dichotomy invented by you. Are you making this up? What everyone has been telling you is there is ONE theory that explains it, called, surprise, surprise, Quantum Theory.

    I'm sorry but I am really quite exasperated by your determined unwillingness to take in what quantum theory says about waves and particles. Until you do this, you are frankly in no position to start speculating about alternative ideas, as you have no idea of how the apparent contradictions between wave and particle behaviour have ALREADY been reconciled.

    As for the rest mass of the photon I'd have thought it was perfectly easy to verify that it is zero. Simply measure light pressure and work out whether the pressure (i.e. the momentum of the light) is fully accounted for by the energy associated with the frequency of the light, i.e. its wave. If it is, then Planck's relation E = hν is confirmed and there is no room for any rest mass.
     
  12. origin Trump is the best argument against a democracy. Valued Senior Member

    Messages:
    9,823
    No.

    Here are a link that will help you to understand light.

    light

    edit - removed one of the links because it would just confuse dav.
     
  13. brucep Valued Senior Member

    Messages:
    4,098
    Nice comments Russ.
     
  14. Read-Only Valued Senior Member

    Messages:
    10,296
    Dav, you really should read the link he provided. And not just read it - but STUDY it, and that means reading and re-reading it SEVERAL times until most of the info given sinks in. It is all true and accurate, however from what you've said in the past, a lot of it may be FAR over your head.

    If you learn nothing else, get at least ONE thing through your head: light (a photon) has NO rest mass. NONE. NADA. ZIP. ZERO. Until you understand that, you will never get anywhere.
     
  15. Russ_Watters Not a Trump supporter... Valued Senior Member

    Messages:
    5,051
    Don't just think. Study and learn. Aristotle spent his time only thinking and most of what he concluded was wrong because of it.
    Then you are choosing to read bad sources (or aren't understanding them). Choose better ones, such as the one provided.
    False. There is only one theory and it works fine. My guess here is that when you say "photon theory" you are under the false impression that photons are a name given for the particle-like behavior of light as part of the obsolete wave-particle duality concept. That's wrong: the photon is the name given to the combined theory that covers both aspects.
    Still wrong.
    Still wrong.
    Where? If you start posting your sources, we can help you to understand them better or explain why they are poor sources.
    Of course. That's a basic consequence of the scientific method: nothing can ever be measured exactly.
    Again: that means you are either reading bad sources or you aren't understanding them.
    Still no.
     
  16. dav57 Extraordinary Thinker Thingy Registered Senior Member

    Messages:
    621
    Ok, thanks guys, sorry if I'm a pain. But surely you have to confess that there a lot of unanswered questions out there and one can't help but explore alternative ideas. One day, someone is sure to stumble on something which will potentially open a door and lead to a new place.
     
  17. Russ_Watters Not a Trump supporter... Valued Senior Member

    Messages:
    5,051
    There aren't nearly as many as you think there are.
     
  18. origin Trump is the best argument against a democracy. Valued Senior Member

    Messages:
    9,823
    Yes, there are unaswered questions. So why waste your time trying to come up with off the wall uniformed speculations on the questions that have ALREADY been answered?????
     
  19. exchemist Valued Senior Member

    Messages:
    6,297
    True and a noble sentiment.

    BUT, any researcher, or inventor, or explorer ALWAYS starts in the library.

    That's because there is no value in trying to reinvent the wheel - you just look a fool and waste your life. So find out what is known - or thought to be known - first and then decide what direction is worth exploring. Physics is a very well-trodden area of science nowadays, so there is a lot that is known. Sometimes I wish we still lived in the c.18th, at which time there were so many gaps in understanding that gentlemen amateurs could make real contributions from their studies as a part time hobby. Them days is over, I'm afraid.

    Please Register or Log in to view the hidden image!

     
  20. dav57 Extraordinary Thinker Thingy Registered Senior Member

    Messages:
    621
    Guys, can you give me a list of unknowns please?

    I'm thinking it might start with (but correct me if I'm wrong):

    Why is the speed of light always perceived as a constant?
    What is dark matter/energy and baryonic matter?
    What is mass and why does it have mass?
    What actually causes gravity, other than presence of mass?
    Why is there inertia?
    What is inside a black hole?
    Where did the universe come from and where will it end up?

    Please Register or Log in to view the hidden image!


    Various quantum mysteries?

    I know we can describe and predict but I'm asking whether we actually understand and explain? What are the current big unknowns that get scientists scratching their heads? Thanks.
     
  21. exchemist Valued Senior Member

    Messages:
    6,297
    No, sorry, I'm not taking part in this. What you are asking for is a short cut to save learning the necessary science. If we give you this list, all that will happen is you will come forward with more half-arsed notions. If you are genuinely interested in science, you will want to learn what is known, not just what is unknown.
     
  22. dav57 Extraordinary Thinker Thingy Registered Senior Member

    Messages:
    621
    Well thanks a bunch.
     
  23. dav57 Extraordinary Thinker Thingy Registered Senior Member

    Messages:
    621
    origin - thanks for your link it was a good read but I kind of knew most of it in any case.

    The sort of thing I get hooked up on is statements like this from the link:

    "Scientists today accept the existence of photons and their weird wave-particle behaviour."

    It's almost like they "accept" because there is no other explanation currently available. I don't like simply "accepting" something and that's why I'm digging in the areas of mystery.
     

Share This Page