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The mechanism behind bouncing...

Discussion in 'Electronic Basics' started by KILOWATT, Feb 2, 2007.

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  1. KILOWATT

    KILOWATT Guest

    Hi... thanks for your attention.

    I just wish to know the precise reason why for example, a digital counter
    may count many pulses on it's clock input when the clock is feed via a non
    noise-free source like a mechanical switch. It is because when the contacts
    makes/breaks, arcing (i've read somewhere that there can be a possibility of
    arcing even at low voltage) occurs, or if it's because of the very rough
    surface (microscopically-speaking) of the switch contacts, were the metal
    molecules grinds (and possibly flexes) together, during switch activation?
    TIA for your reply.


    --
    Alain(alias:Kilowatt)
    Montréal Québec
    PS: 1000 excuses for grammatical errors or
    omissions, i'm a "pure" french canadian! :)
    (If replying also by e-mail, remove
    "no spam" from the adress.)
     
  2. default

    default Guest

    You got it - on a microscopic level the metal contacts will create
    high frequency noise (a good scope may be necessary to see it). Some
    reed switches were produced that eliminate the bounce by using
    electrodes with a mercury coating in an inert gas capsule.

    Ironically, they were also used with mechanical actuators to produce
    fast rise time pulses to test semiconductors. Nothing says "on" like
    mercury coming together.

    Some dry switches deliberately induce a wiping action on the contacts
    which prolongs the switch life, but creates more noise.

    The clock input of logic circuits is fast enough to count the
    transitions.
     
  3. John Larkin

    John Larkin Guest

    Bouncing means bouncing. When contacts collide, they, well, bounce,
    like a ball hitting the floor. Multiple contacts are made and unmade
    until it settles down. This is quite visible on an oscilloscope.
    Small, low mass contacts have a higher mechanical resonant frequency
    so tend to have higher bounce rates and settle faster. Mercury-wetted
    contacts don't bounce at all.

    There's no significant arcing contribution at low voltages.

    Incidentally, for both wet and dry contacts, the initial electrical
    connection can have sub-nanosecond risetime.

    John
     
  4. The atoms of the two materials are not configured in such a way that there
    is complete contact. If they were then the materials would be fused. Since
    there are not fused and they slide there is friction involved and this
    friction causes the contacts to move farther a part and then closer
    together. So the average distance between the constants is changing
    significantly campared to when is not moving and they are making good
    contact. So now the electric field is changing because of the distances
    changing between the contacts. As the contacts move farther away the field
    becomes weaker but now we have a capacitive effect. This effect creates a
    force between the contacts that attract them. One now has a kinematic force
    pulling the contacts away(so it can slide), one of friction that wants to
    stop the slide, and one of capacitance that is attractive(I'm sure there are
    more too).

    Anyways, So there are all these forces that are interacting and the end
    result is this oscillation of the contacts moving toward and away from each
    other. One always gets "arcing" but thats kinda relative turn. (In some
    sense all electronic flow is "arcing".) Generally this term is used when
    there is significant macroscopic arcing and this requires much higher
    voltages than the microscopic arcing that always happens. (Its just a matter
    of degree). This oscillation that happen is called bouncing and the net
    effect is to increase and decrease the resistance but with a trend towards
    increasing it(which happens very sharply when the contacts finally break
    away).

    When a switch bounces it does turn on and off instantaneously a few times
    then finally settles on off. Nothing is every instanenous in the real
    world. The net resistance is dependent on many factors and one of them is
    the distance between the contacts. Theres a point where the distance becomes
    so great that microscopic forces do not have any significant effect. The
    bound that you see on an oscilloscope occurs right at this point where D
    becomes more significant and the other forces do not. This point has to do
    with how much of the two contacts are actually in contact although it
    happens over the whole surface since some points on the contacts are more in
    contact than other points. In this case we have an average that approximates
    the whole surfeces very well unless the contacts are very distorted.


    I guess ultimately the effect I'm talking about is sorta middle ground
    between the atomic and the macroscopic. Whats really important here is what
    happens when the two contacts are about to completely leave each other and
    not what happens before(although it could be significant it is just a
    smaller version of the main one). Once you understand this then its not
    hard to see that it happens many times before but just on a smaller and
    smaller scale. (One could say that bouncing is always happening so its just
    a matter of degree).

    Anyways, I'm kinda rambling there but maybe it will shed a little light on
    your problem.

    Jon
     
  5. Ben Jackson

    Ben Jackson Guest

    I knew I shouldn't have paid a premium for these "high speed digital
    buttons"!
     
  6. John Fields

    John Fields Guest

     
  7. John  Larkin

    John Larkin Guest


    Sorry, but that's all nonsense. At low voltages and currents, switch
    contacts bounce for purely mechanical reasons.

    If your field theories were true, the applied voltage would radically
    change the bounce waveform. It doesn't. Try it.
    Metallic conduction is not "arcing." Arcing is gaseous conduction.
    Vacuum tunneling happens too, but the range is just on the order of an
    atomic diameter, not important for things like switch contacts.

    John
     
  8. Um, and you seem to think that mechanical bouncing is some real thing. Its
    an abstract concept. There is no real think as bouncing. When a ball bounces
    you think that the surfaces are idealized. No, they are governed by quantum
    mechanics. Believe it or not, doesn't matter ot me.
    hmm. so the waveforms are exactly the same? They do not scale with voltage?
    You seem to think that ohms law doesn't apply here? V = IR or did you not
    learn that? What do you really think these waveforms will look like? Do you
    think they will be perfect unit step functions? Get into the real physics
    of it and stop trying using idealized descriptions of the behavor.

    http://www.ece.uci.edu/rfmems/publications/papers/mems/C021-EUMTT99.pdf

    http://www.scienceprog.com/dealing-with-switch-bounce-problem/

    Do you really think that the effects I'm talking about are going to
    radically change the macroscopic scale? The time scale is femto or less and
    the forces are fN or less. (although the above analysis are still idealized)

    Your logic is like saying a resistor behaves exactly the same no matter what
    conditions. Your a bafoon in thinking that everything is some simple
    mathematical equation that you learned in cal 101.

    You think that a resistor doesn't change its "waveform" with voltage? R =
    V/I. What happen when V is very low? what about when V is very high? What
    about most of the time? Most of hte time R is the APPOXIMATELY constant.
    THATS RIGHT!!! A resistor doesn't change its "waveform"(which is wrong way
    to put it as switches and resistors are not waveforms) for a wide range of
    voltages. If this what the case then they would be practically useless.

    Did you ever take quantum mechanics 101? Hell, even basic physics supplies
    an approximately correct answer. Coulomb's law for the contacts state
    something like

    Sum(k*Qi*Qj/r_ij^2,i=1..N)

    (this is better described in a statistical quantum fashion but I don't want
    to confuse your little brain)

    Do you think that distances in this equation have some special meaning
    between when a switch is open and not? Sure there is a point where the
    strenght of the field drops off almost to 0 but it is not instantaneous.

    The OP asked for the microscopic answer and not something you read out of an
    electricians manual.

    (BTW, show me some waveforms's from two different switches using the same
    voltage and lets see if they are even close. Hell, show me two waveforms
    from the same switch using the same voltage and lets see if they are even
    close.)

    So we cannot have an arc in a vacuum without any gas? Hmm, can you prove
    this? I think this would go to explaining a lot about vacuum tubes(I guess
    they don't "arc" or must contain a gas(a significan't amount to explain the
    arcing)).

    It may not be significant to you but you are not the genius you think you
    are. People like you are satisfied with any explaination that doesn't
    confused them people like the KILOWATT want to know the real reason why
    things work. You take it on faith(sure, you might look at a few switch
    characteristics using an oscilliscope but then you do not care to go
    farther) while he wants to know the real reasons. The difference is one of
    religon and one of science.

    The same factors that cause friction are at work with a mechanical switch.
    You can ignore this all you want and thats fine. But don't try to act like
    the world is some idealized place that is perfectly described by few simple
    mathematical equations. (all equations are wrong to some extent and some are
    better than others. Usually the better equations are more complicated).

    Your logic is like "A diode is a switch" while mine is "A diode is a device
    that can behave like a switch but this is because of the properties of the
    material. (then I'd have to talk about doping, holes, drift, junctions,
    valence electrons, pauli exclusion principle, etc...). Rarely is any simple
    explination the full explination.

    If he asked what was switch bounce then your answer is good enough. What he
    asked was what was the microscopic reason for switch bounce. Now I didn't
    talk about quarks because obviously that level is to low and there is no
    need(as far as we know). Even the theory of friction at the atomic level is
    not know that well. But this is the best level to explain it because you
    get at the heart of the reason. Now my explinations might not be perfect but
    just because you think they are wrong doesn't mean they are. I also never
    said the effects were significant, but there is a macroscopic effect.

    Its fine if you want to act like the world is not made up of atoms and
    idealize everything. I have no problem with that. But when someone else
    wants to know more then don't try to make them believe what you believe.
    Only thing I can think of is that your afraid that if they go and explore
    that they might prove you wrong. So you care more about looking right than
    being right.

    Did you factor in resistance into your switch? Didn't think so. Do you know
    that resistance depends on voltage? (doesn't matter how, just that there
    exists two different voltages that produce two different values of
    resistance). You know that voltage and heat are related? (Even directly.
    Not that its significant. Even absolutely zero cannot stop an atom from
    moving.)

    Anyways...
     
  9. John  Larkin

    John Larkin Guest

    That paper describes a simulated mems switch that is electrostatically
    operated and *never* makes electrical contact. That's not very
    relevant to a conventional mechanical contact that is mechanically
    driven and *does* make electrical contact.

    Get an oscilloscope, a toggle switch, a power supply, and a resistor.
    Set up to observe the bounce waveform. See if changing the applied
    voltage changes the nature and timing of the bounce waveform, which is
    must if electrostatic forces are significant. Of course the voltage
    will change when you change the voltage; I won't argue that point.

    This is real physics: try it.


    That says nothing about the physics. And it's actually easier to
    "debounce" a pushbutton: just read it every 50 milliseconds and accept
    what you see.

    No, I'm an engineer who knows how real parts actually behave.
    Vacuum tubes don't arc in normal operation; thyratrons do. Arcing is
    plasma (ionic) conduction. Vacuum tubes operate by electron-only flow.
    Metals conduct through movement of conduction-band electrons.

    John
     
  10. John Fields

    John Fields Guest

    ---
    That's not true.

    When the contacts come to rest after the bouncing period is over
    they will either be in intimate contact or they will be completely
    separated.
    ---
    ---
    Which, indeed, they are until the coil is de-energized and the
    return spring exerts force on the armature, breaking the microscopic
    weld(s) and allowing the contacts to open.
    ---
    ---
    No. The friction you're talking about is only about the contacts
    rubbing against each other when they're making or breaking and is a
    second order phenomenon compared to bounce, which occurs when the
    contacts alternately make and break when the coil is energized.
    Bounce also occurs when the armature is de-energized, but to a
    lesser degree, and is caused by the moving contact skipping across
    the stationary contact when the coil is de-energized.
    ---
    ---
    No. The high-level bouncing behavior is due only to the gross
    mechanical characteristics of the contacts and has vanishingly
    little to do with the microscopic effects, which are at least six
    orders of magnitude smaller than the mechanical effects, I'd guess.

    Do you have some hard numbers which would prove otherwise?
     
  11. John Fields

    John Fields Guest

    On Sat, 03 Feb 2007 21:58:27 GMT, "Jon Slaughter"

    ....
    Why are you being so angrily defensive?

    Contact bounce is nothing more than a spring-loaded screen door
    bouncing back from the jamb when it's let go early.
     
  12. Electrostatic forces? No one said anything about electrostatic forces. That
    is kinda irrelevant too as electrostatic forces are forces generated by
    charges not in motion. When charges in motion one has electodynmaics which
    is a completely different phenomena(which is not decribed in parameterized
    way on time because it would not explain the magenetic fields created.

    What your thinking is that these minute forces some how change in a way on
    voltage that is not linear. This is true but only in a certain range of
    voltages. Just like a resistor is "linear" but actually this is not true at
    all. its an apporoximation that in no way explains the true mechanisms of
    resistance. If you could see the true "waveform" then every one would be
    different even for the same resistor. Its more like a stochastic brownian
    process and you see its statistical average. I doubt a 1GHZ scope could even
    capture those subtle effects.

    My original point to you was that even though these interatomic forces are
    "random" doesn't mean the macroscopic behavor is random or even close. Just
    like gravity of the earth is extremly complicated and due to an extremly
    large number of small forces we can still describe it by g at the surface
    and it is quite accruate. In some sense the large number of "random"(not
    truely random but best described by random processes) events have a simple
    non-random macroscopic effect. One even can have an effect that is simply V
    = IR. The microscopic behavor is extremly complex and somewhat random but
    its pretty much perfectly described by that equation.
    Yes, I was only showing it because of the waveform which I believe is the
    tyep of waveform that you think real switches actually exhibit.
    Really? Do you know that all materials are made up of atoms and atoms are
    quite random(Stochasic is a better term). That is, trying to describe the
    motion of any one atom/electron is impossible(not even because its hard but
    becaues of the uncertainty principle) but all the atoms of a material taken
    together exhibit a property that is independent of any single atom. If this
    were not the case we could not have any simple laws describing those
    macroscopic properties(cause they would change so easily and we could never
    do any experiments with them).

    What your trying to do is talk about engineering when teh OP wanted to know
    about the physics. Engineer's could care less about what causes the
    properties but only care about the dollar.
    Ok, then maybe I'm not using some technical definition of arcing. If arcing
    must involve a plasma to be called arcing then thats fine. I was wrong. I
    normally just think of arcing as electronic flow. I could say that any time
    an electronic flows through a material it is arcing from one atom to the
    next. In some sense this still works with your definition since the
    conductor could be though of a plasma but ofcourse this is wrong by the
    defefinition of plasma. Ofcourse when electricity arcs in air we don't
    normally think of it as creating a temporary plasma(that only lasts for
    probably a ms at most) but we still say it arcs? Or do you just call this a
    electron flow.

    When the electrons flow in a flow the tube they do flow without ionization
    because there is no gas in the tube to interfer with the flow. Put a gas in
    the tube and you get ionization and if there is enough then a plasma. While
    not technically correct, to me this seems to say that arcing is more matter
    of degree than just a simple black and white definition.

    I think here that arcing and electric flow are very similar and overlap.
    Ionization usually happens(if not always) when there is electric flow.
    Metalic conduction is just electric flow because the metal atoms are so
    easily ionized while in ionizing a gas tends to be a lot harder(more work
    for the electrons to flow until it is already ionized).

    Anyways, doesn't matter so much as thats not what the OP asked about.

    The main point I'm trying to make to you is that your ideal view of how
    things work is not how they work. Maxwell's equations do not govern true
    electronic flow. It assumes that the current density is continuous and this
    is far from the case. It works because on such a macroscopic scale one does
    see what looks to be a continuous medium. If you only ask about what
    happens on that scale then the equations are valid(Similar to Newton's law
    and the speed of light). But to describe what happens at the microscopic
    level you have to use quantum mechanics. If you want to know how total
    macroscopic effect of a contact switch then Maxwell's equations along with
    classical dynamics work just fine. If you want to know what really happens
    you'll have to bring in QED and QM. Its just that simple. Classical physics
    was not formulated at the level of QM and it was only important for
    macroscopic purposes(Not that this didn't stop them from hypothesizing at
    the atomic level). QM is formulated on the atomic level(and some of it at
    the sub-atomic). It has proven that when its laws are taken in a statistical
    sense on the macroscopic level they reduce to the classical formulations.

    http://en.wikipedia.org/wiki/Friction

    Try reading that and you'll see that they do bring in EM a little but there
    equations or not formulated on EM. The reason is simply that the macroscopic
    effect can be described in such a simple fashion and this is how they were
    found. Those that discovered these "laws" didn't start with the atom but
    started with the macroscopic effects and tried to formulate descriptive
    mathematics out of it.
     
  13. Because you guys always seem to think that your way is the right way. I know
    you guys are not stupid but it seems that you take a simple view of the
    world and if someone else wants more info then you act like they are stupid.
    You think, say, that if you measure the V-I curve on a resistor and see that
    it looks like a perfectly straight line then it must be.

    You neglect all the other factors involved. This is fine if you don't care
    about them but if someone else does then you tell them what you have
    observed and that is what they should believe.

    To me, its like your trying to tell someone the world is flat. Now because
    it you believe it you don't doubt that it is. It must be. It sounds as if
    you think you know everything. And while you guys may not be wrong in most
    cases in some way or another, usually you have an idealized or even a narrow
    minded view of things. If you never experienced it then it must not be
    possible.

    Usually when someone asks something one doens't get a response like "In my
    experiences I have no had this happen" but instead "It can't happen". Now
    the problem with the second is that history should have taught you that
    nothing is impossible but if you really believe it then you should have good
    reasons. So just state them. "It can't happen and heres why...". Better
    yet, "I don't think it can happen and heres my reasoning...". The first
    sounds like an arrogant fool while the second one sounds like a rational
    human being. Ofcourse maybe you can convince most people with the
    "authority" loic but its wrong and should specially not be used in a
    scientific place.

    If you disagree with something then just explain why. Don't act like you
    know everything about everything because you could be wrong(not saying
    you/they do this all the time but it happens to much in this NG).

    I could be wrong on many things I say. I'm not perfect and I do not know
    everthing. But I try to rationalize everything with proof. Sometimes my
    logic is faulty and sometimes I use bad evidence. I will admit when I'm
    wrong if there is good counter logic involved(and not the authoritative
    logic). Maybe you guys were kings in another life and are used to having
    everyone do what you say no questions asked?

    Actually any reasonable person who has a desire for knowledge would love for
    everything they say to be questioned because it gives them a chance to
    understand explain to others and reinforce there own understanding(or change
    them if necessary) there view. Many times when I have "argued" with others
    I have come up with a better understanding of my own point of view.
    Sometimes I have also realized that my original logic was quite shakey or
    even wrong. This has happened to help me be self-analyzing on much a
    greater scale than most. Although in the last couple of years I've lost
    almost all that ability as I do not hang around with any intelligent people
    any more. Maybe thats why I get defensive, I don't know. I guess I just see
    this arrogance everywhere and I feel that it does no good for humanity. (Its
    getting so bad that eventually everyone will not care what others think and
    believe they are kings)

    Anyways...
     
  14. So can you shear a part a solid piece of metal with a spring? Its a matter
    of degree. If the contact interface was completely "fused" then thee would
    not be any contact interface(assuming the same material is used for both
    contacts).
    The friction is due to electrical forces. There are only 4 known
    forces(well, 4 main ones) in the world. Gravitations, Electrical, Strong and
    weak. Gravitational is like 10^(-40) smaller than electrical. The strong
    and weak work only as a sub-atomic level.

    So are you saying there is some other forces involved?
    Sure, but we are not talking about high level. The high level is strictly
    due to the averging of the microscopic. See above about the forces.
    Yes I do. 4 forces, 1 is too weak to be of any use for this problem, the
    other 2 are too weak at the distances we are discussing.

    Here, I'll even get you a link with some pretty pictures:

    http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html

    How do you explain yourself out of this one? Just cause you have a quarter
    doesn't mean the quarter is smallest denomination. (Ok, stupid analogy but
    works).

    All of reality is based on these 4 forces(at the present understanding of
    reality). You can ignore that fact and just look at the infituide of
    outcomes that these forces produce but you are then neglecting what really
    happens. Its even much more complicated than this but these are adaquate for
    the OP's problem. He asked what was happening at this level and these are
    the tools one has to use to explain it. You cannot explain something at a
    lower level higher level tools(ok, maybe a little but theres no guarantee
    that it will work).
     
  15. John Fields

    John Fields Guest

    ---
    To a first approximation, it is, and for the purposes of this
    newsgroup that's good enough most of the time.
    ---
    ---
    Yes. And rightfully so. In the absence of a specific request for
    the microscopic, the macroscopic explanation will generally suffice.
    If it doesn't, then the onus is on the querant to ask for more
    detail. You seem to think that everyone wants to know the minutiae
    of "why", and that's just not the case. In this instance the OP
    asked for an explanation of why a noisy switch causes a counter to
    count falsely, and the answer is: "Because the switch contacts make
    and break many times before they settle down, causing multiple
    transitions at the counter's clock input."

    This can be shown to be true by using a mercury-wetted reed relay or
    switch in place of a conventional switch. Doing that will result in
    precisely one count made for each make-break cycle of the switch.

    That suggests, to me, that the reasons you cited for the miscounts
    (the electric field attracting or repelling the contacts, for one)
    are flawed, since the very mobility of the mercury film would
    certainly cause it to be more affected by that field than a big mass
    on the end of a spring would be.
    ---
    ---
    It is, in places, so why shouldn't I tell them that if the micro
    view is necessary?

    You seem to be saying that when it's convenient for you to use the
    macro view you will, but that no one else is allowed to.
    ---
    ---
    Don't you think that lumping us all together as "you guys" is taking
    a narrow-minded view of things? That is, you're doing exactly what
    you say it's wrong for us to do.
    ---
    ---
    Can you uncook an egg?
    ---
    ---
    Sounds to me like you're getting a little authoritarian there.

    In the first place, If I want to make an all-encompassing statement
    and not back it up with proof, that's my business. I'm certainly
    not bound by _your_ rules, and if you have a problem with the
    statement, then the burden of proving it false is on you.
    ---
    ---
    Well, the very act of disagreeing with someone is saying: "I think
    you're wrong" or just plain old: "You're wrong", which means that
    you think you know more about it than they do, so if you disagree
    with the way people post in this newsgroup that means that you know
    better than they do about how they should post. Don't you agree?
    ---
    ---
    "If there is good counterlogic involved" means that you get to be
    the judge of what is and what isn't good counterlogic, so you get to
    be in the favorable position of deciding whether you're right or
    wrong by deciding whether your opponent's logic is good or not
    regardless of whether your opinion is right or wrong. Handy, no? ;)
    ---
    ---
    Not true. I wouldn't love being questioned in a hostile manner by a
    person who is frustrated by his inability to understand the answer
    to the question and is trying to prove me wrong because of his
    inability to admit to being wrong.
     
  16. John Fields

    John Fields Guest

    ---
    Of course. Have you ever seen how a set of contacts is made?

    Usually one contact is flat and the other rounded (or they're both
    rounded) so that when they're in contact with each other only a
    very small area of metal is involved in making the contact.

    That way, when the contacts bounce and microscopic welds are made
    between the contacts, the spring will have the strength to break the
    welds and open the contacts.
    ---
    ---
    It doesn't make any difference if the metals are dissimilar or not,
    at the weld there is no "interface".
    ---
    ---
    Nope, but I'm talking at the macro level where when two materials
    are pressed together more and more tightly it becomes more and more
    difficult to slide them past each other.
    ---
    ---
    I am, because that's all that's needed to describe contact bounce in
    response to the OP's question.
    ---
    ---
    Yes, but so what?

    What the OP wanted to know about was what caused the false count and
    I can assure you that the electrostatic attraction or repulsion of
    the contacts has nothing to do with it. It's merely the contacts
    making and breaking repeatedly until they settle down, and that's
    caused by a movable mass on the end of a spring bouncing against a
    fixed mass.
    ---
     
  17. Except when it doesn't suffice. Sometimes its a naive view in that some
    people when told that will believe it to be a fact when its not. Just like
    ohms law is not a fact. Its a law that breaks down under certain conditions.
    When people are just learning about these things they tend to be reluctant
    to question. So I think it does everyone better if instead of trying to
    state things as fact they are stated in the right context. (the context of
    the right level of approximation for the job)
    But the OP did ask for such and explination and I tried my best.

    "or if it's because of the very rough
    surface (microscopically-speaking) of the switch contacts, were the metal
    molecules grinds (and possibly flexes) together, during switch activation?
    "

    since he brings in this microscopic level I can only assume he wants a
    corresponding answer in the microscopic. (wether it is relvant to engineers
    is irrelevant to me. He ased a question and I would answer it in his context
    the best I can. Its not my job to question his reasons why he wants to know
    this as I assume he has a better understand of his motivations than me. )
    Because when you *tell* someone they might think that that is the answer and
    only answer. Then this propagates arrogance. Those people then grow up tell
    someone else the "fact" and everyone thinks its a fact. Then comes along
    some guy that questions it and he's jumped on by everyone else. Its sorta
    like how some laws are. Someone creates a law for a specific reason and
    then many years down the line the reasons are forgotten and the law is
    enforced even though its original reason for existing makes it invalid. But
    it is enforced because people cannot think for themselfs(most people). They
    don't question authority because they are afraid. To many people think facts
    are a popularity contest. Life just doesn't work that way.

    Again, the issues I tend to have with you guys is that you seem to think
    that what you think are facts must be facts for everyone else. This is not
    the cause and I think you guys are smart enough to really understand that
    but its just easier to act like everyone has the same set of facts. But the
    point is that just because you believe something as fact doesn't mean you
    should state it as fact to someone else. I believe that it is a
    fact(ofcourse its more of belief) that "god" does not exist. I do not state
    this as a fact when talking to other people though and I accept there
    opinions as long as they do not try and make it a fact for me. When they
    try and make me except there facts they better prove it to me and not just
    try and force feed it to me. This, to me, is exactly what you guys try and
    do. You force feed people your "facts" when in reality they are not facts at
    all(usually). Actually nothing is fact so we shouldn't force feed anything
    to anyone else. We present the evidence and let the other person decide. If
    they come to a different conclusion then so be it. Its not our job to get
    everyone else to believe what we believe. Why? Because facts are not a
    popularity context. Majority does not rule logic or facts. So many people
    believe this(Specially religious people) that its disgusting. Some people
    think that if they can get enough people ot believe what they beieve then it
    will make it true. I don't think you guys believe that but many times you
    act that way. Else you wouldn't get mad when someone disgree's with you or
    asks you to explain yourself.

    no, for all I know I could be completely wrong. I do have to think I know
    something though as then I would be quite useless. I don't know everything
    and I'm not even close. I could also be wrong in everything I say. I have a
    minor in physics and have taken quantum mechanics, I have a degree in math
    and have taken over 200+ credic hours. Does this mean anything? Maybe...
    maybe not. I have forgot a great deal of what I have learned and could have
    easily gotten things confused. But sure, there are somethings I believe
    very strongly about just like you do. BUT I rarely see you guys give any
    evidence to support your claims. I will happily give my evidence and
    reasoning if it is asked for in a way that isn't belittling. Ultimately I
    want to learn and share knowledge and not get into childish games. Sure it
    happens and sometimes maybe its my fault but that is not the goal for me. I
    do not come to this newsgroup and offer help when I can feed my ego. I come
    here to learn and thats pretty much it. Who knows what I can learn by
    helping someone else out. Maybe it will lead to things that I can't imagine
    now.


    Sure. What else am I suppose to do. Well, maybe I am. But I do have
    experience with you, Larkin, and several others that do the same sorta
    things so its not such a bad approximation. Ultimately we will run into
    issues like this because thats life and its full of contraditions. Its not
    a narrow-minded view as it is simply being lazy I cannot possibly talk about
    all of you guys seperately and describe all the reasons I have come to my
    conclusions(would be a waste of time to do so). Similarly as you make the
    macroscopic approximations to make things easy I have to make things easy.
    If you asked "Why do you feel this way about me" then either I would tell
    you the reasons(and if they are not proof enough for you then you could ask
    me and then I would try to find the proof. Maybe I would learn that it was
    my fault and a made a mistake or misinterpreted something. Who knows) or I
    would tell you I don't have time to waste on it(cause unfortunately theres
    only so much one human being can do).

    So true, I might be guilty of it and sometimes I am guilty of the exact same
    things you guys do. I have no problems admitting it. Its not right but
    sometimes it a necessary evil.

    Do you know that just because you have no proof of the existance of
    something does not mean is is false? We know by the incompleteness theorem
    that there are things that are even unprovable. We know also that we can
    prove somethings about something but not find any specific examples. (We
    might be able to prove that there exists something but actually never be
    able find it.)

    Quantum mechanics also tells us that time can be reversed(and must be) so
    maybe one can find a way to uncook and egg. This is assuming QM is true and
    we do not know htat 100% but it looks like it. So sure, I don't know how to
    uncook an egg. But I don't know how to do a lot of things but that should
    not stop me from trying to learn.

    Maybe. That is not my goal as I'm just trying to express my point of view.
    Sure. I cannot change that. I hope that you understand that it is not as
    productive, atleast I hope you would reason to that because I believe the
    alternative is much better. We can learn a lot from history and while
    history is not always right it does help a lot. I cannot make you do
    anything but only offer evidence that its probably not a good idea to think
    like that. The evidence simply might be wrong or wrong to you(some stuff is
    just relative and we can't escape it).

    No, not necessarily. I do see your point but if I say someone is wrong its
    more "I think your wrong, please explain why." Its not as polite to just say
    "Your wrong" and I try not to say it like that. What I really mean is
    "EXPLAIN WHY!!". Why do I say it like I do? Because if I say "Your wrong"
    then most people that actually understand why they think they are right are
    going to present the evidence if they want to explain. Atleast thats what I
    do. I also know that if people get angry when they are told they are wrong
    then it probably means that they don't really know why they believe what
    they do. (else why get angry. If a 2 yr old kid comes up to you and says
    "Your stupid. The earth is flat!" do you get mad and punch the kid in the
    face? I would hope not.)
    But this isn't a chess game. We are not trying to play king of the
    mountain. We are hear to learn, no?
    I agree. But I do believe that I rarely question people in a hostile
    way(saying "Prove it" is not hostile). I only get that way when someone does
    or has tried to force feed me there garbage and I have found out from much
    more reliable sources that they were wrong.(maybe the sources were wrong but
    I have to believe someone).

    Several of the problems I have had with "you guys" is that I have asked a
    question about something and I was told something that may or may not have
    been true. I have had contradicting sources and so I ask you to explain your
    reasoning and evidence and instead I get jumped on. When that happens I do
    not like it at all because now that means I will not learn anything about it
    except by going somewhere else. It also seems to point that either someone
    doesn't want to share there knowledge(they only want to dictate) or they
    don't have the knowledge(so they pretend). In either cause it means I will
    not learn anything from them any farther.


    I think I'd be more of the chopped liver than you guys. I think you guys are
    normal, probably pretty intelligent people but have lived in a hostil
    enviroment that makes you a little to rough for me. I'm like a shark and I
    can smell a drop ego a mile away. Sometimes I do over react and sometimes I
    do let my own ego take control. This is not my goal. I'm only human just
    like you guys. But what I do know is that when things become childish that
    nothing important will probably come out of it. I understand that you want
    to be treated with respect and that you have worked hard to learn the things
    you have but you have to understand that I'm not the type of person that
    takes anyone elses logic or knowledge on faith(even if its at my own
    perile). I do this because I like to learn for my self. Just don't take it
    the wrong way. If I sound like a kid sometimes its because maybe I am.
    Sometimes I let my ego take control and all that. Again, I'm only human. I
    think the main goal, whatever the problems is ultimate to learn(sometimes I
    wonder why I think this way as it can be quite frustrating ;/). Anything
    that gets in the way is a distraction.

    I suppose. The problem is that there is no king without someone to clean the
    toilets.

    Jon
     
  18. I'd like to see that.
    Yes, but this is explained in a microscopic way.

    Sure it does. Sheesh. Do you remember in physics when doing experiements
    with friction? You would slide different materials along a flat surface and
    measure there coefficient of friction? Did you ever remember reading about
    the case when the two materials were the same? (if they were perfectly
    clean then they could stick together much easier than different materials).

    This is due to the crystal structure of metals. You don't have this if the
    metals are different.

    Not sure wha tyour getting at:

    It is not, however, a fundamental force, as it originates from the
    electromagnetic forces and exchange force between atoms.

    The key is originates. It means that it can be "explained" in terms of the
    fundamental forces(which there are only 4 so essentially everything can be
    explained in terms of that).

    Yes, but how can you even talk about that? You act like the macroscopic
    level is something totally different some the microscopic. The macroscopic
    is just a manifestation of the microscopic. If you want to talk in those
    terms then thats fine. But then we are talking about different things.
    Although since the macroscopic is derived from the large scale microscopic
    my ideas should, if correct, explain the macroscopic in a much more detailed
    way.

    Well, here we have to disagree. Since the OP talked about the microscopic
    effect of "friction"(and by the wiki page is the EM and interatomic forces)
    then I assumed he ment at the microscopic level.
    Yes, that is true. BUT he asked why in terms of the micrscopic. He did not
    asked why in terms of the macroscopic level. I already pointed out the
    quote.

    Ok, you don't have to believe me...

    Ok John. All I can say is that we'll have to disagree. I believe you are
    wrong here. (in the above statement).

    My only logic evidence I can give you is that:

    Physics as described 4 fundamental forces. These forces as the only forces
    that exist. All other forces are some combination of these. This is physics
    talking and not me.

    http://en.wikipedia.org/wiki/Fundamental_interaction


    From here one doesn't even have to do any estimation. If there are only 4
    forces in the physical world then any macroscopic forces must be derived
    from these 4. Friction is not a fundamental force. It is based on the
    interactions of a huge number of atoms and the 4 forces. Mechanical
    "bounce" is not due to some macroscopic force(although we can use an average
    to get it) but only due to the 4 forces. I don't see how you can conclude
    anything else. I am not saying that we cannot talk about some derived force
    because its almost necessary. What I am saying, now atleast, is that
    everything in the physical world is due to these 4 forces(assuming they are
    the correct). Any force that you claim is "fundamental" better be one of
    these 4 forces and if its not then you better prove it(atleast make enough
    of a convincing argument so that it is accepted as a new fundamental force).

    If you want to talk about friction or bounce or whatever and ignore the fact
    that they exist only because of these 4 forces then you are doing yourself a
    disservice. You might get along just fine with beliving that but your no
    different than those who thought the world was flat or that the thunder god
    was angry at them.
     
  19. ehsjr

    ehsjr Guest

    Jon Slaughter wrote:

    You calling Larkin a "bafoon" ?

    Congratulations! You have just won the
    "Most Ridiculous Comment of The Year" award.

    Ed
     
  20. KILOWATT

    KILOWATT Guest

    Thanks to all for the informative replies. Sorry that my op generated some
    arguing but anyway, i've learned from it. ;-)
     
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