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  1. May 12, 2003 #1
    This issue was brought up in the thread, "I think therefore I am", by Manuel_Silvio; and I wanted to get some answers to the question: Is Causality necessarily true?

    Here is an example that Manuel used, and I think it sheds some serious light on the matter: Suppose I flip a coin, and get "tails" every time, and there's a mosquito on the window-sill. Now, do I attribute my having gotten "tails" every time to the mosquito's presence? Let's say I do it 100 times (with the mosquito still present), and get "tails" every time, do I now attribute it to the mosquito's presence? What if, after the mosquito leaves, I flip "heads"? Do I now conclude that it was the mosquito's presence that caused me to continually flip "tails"?

    Most would find this preposterous, and rightly so, IMO. However, what if everything that we have ever believed was caused by something we did, was actually going to happen anyway?

    Any and all comments on this subject are welcome.
  2. jcsd
  3. May 12, 2003 #2
    I think most of us learn these things as we get older when we realize it's not always our fault (as others might insist).
  4. May 12, 2003 #3
    Let me give an example of cause-and-effect that we might take for granted: I slap someone in the face, and they recoil in pain. Every time, out of 100, I slap someone in the face, they act hurt. So, I assume that there is a "causal bond" between slapping and being hurt. But what if there is no such connection? What if the person was going to recoil in pain anyway, and I just happened to be slapping them at the same time (much like the presence of the mosquito could have just been coincidental).
  5. May 12, 2003 #4
    Well then maybe we should put them up for an Oscar, or an Emmy? Or perhaps their "acting" would be the causality that leads to some other reward. Like to sue your ass off or something!
  6. May 12, 2003 #5


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    The truth is that you need to do more than just show a correlation of occurances for causality. You need to show a direct link, in terms of theoretical logic, and practical evidence. Millions of things just happen to occur at the same time - very few are the cause. The chance that something just happened to appear to be the cause is generally very small, but that is a big risk in the use of statistics.
  7. May 12, 2003 #6


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    Greetings !
    Causality is the result of the concept of time.
    This concept in turn appears to be
    basic and thus unprovable and its origin
    appears unexplainable.

    So, is it true ? Or rephrasing that - most likely ?
    Yes, it does appear to be most likely from
    observation but QM appears to change it
    somewhat by changing its previously defined
    connection with time.

    Live long and prosper.
  8. May 12, 2003 #7
    And yet some causes are more readily apparent than others, for example the dominoe effect, where all it takes is one little nudge of a finger to set the whole chain in reaction ...
  9. May 12, 2003 #8


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    Causality is NOT true, at least in some universal sense.

    The definition, as previously mentioned, requires that causes precede the effect in time. When a "cause" does not precede the effect, it is - by definition - not a cause.

    Since quantum events occur for which there is no predecessor cause (such as when quantum observables do not take on discrete values until the wave state is collapsed by observation), the candidate event cannot be an effect. The effect (value of the observable) occurs simultaneously to the observation (when the wave function collapses). Because cause and effect occur simultaneously in such cases, causality does not apply. QED.
  10. May 13, 2003 #9
    Wouldn't you have to observe people recoiling in pain from an apparent slap, when in fact no slap was delivered before you could conclude they would have recoiled in pain if you had no delivered a slap?
  11. May 13, 2003 #10
    But is Causality necessarily true?
  12. May 13, 2003 #11
    No, I can't conclude that. However, I can't conclude that I was the cause either. They are both possibilities.
  13. May 13, 2003 #12
    But if the quantum observables do not take on discrete values until the wave state is observed, then the observer would be the "cause", wouldn't it?

    I had thought of this example before, but (as I stated above) I'm not sure that it's independent of a "cause".
  14. May 13, 2003 #13
    Re: Re: Cause-and-Effect.

    *Non-sequitor Alert* How in the world does it's being basic make it unprovable.
  15. May 13, 2003 #14
    I advise you not to try it. It's not for the benefit of science to slap someone in the face.
  16. May 13, 2003 #15


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    Re: Re: Re: Cause-and-Effect.

    My guess is that because it is fundamental, and hence not actually caused by anything else, the only way to deduce it is to use inductive logic. Ie, you can't deduct it from other axioms - it IS an axiom. So, by default, it is kinda unprovable, just being something we assume because it seems to make sense.
  17. May 13, 2003 #16


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    Greetings !
    Well, if you can't define it (like I can
    define an orange, which is apparently not basic
    according to what we know, as a group of certain
    types of molecules in certain amounts and ratios)
    you can't prove it either, can you ? :wink:
    I mean, you could define time as causality
    but then how can you define causality ? It's

    Anyway, the reason I mentioned all of this
    is because you asked about the "truth" of
    causality and the word "truth" is right up
    my "red alert" alley. (Guess I should relax
    a bit... )

    But, I guess you weren't digging that deep and
    just wanted to ask if it's the likely choice
    for now. Well, I think it's not according to the
    classical "cause before its effect". I mean,
    QM disrupts these relations - both the "before"
    and the "its" part. According to QM we can
    have instant and in relativistic reference
    frames even opposite positions of cause and
    effect. Further more, it is impossible to
    define the exact cause or the exact effect.
    So, I guess the clasical meaning of causality
    is long since dead and barried.

    Does something remain ?
    Well, yes I think that "something" that we
    can call causality or maybe find another word for
    it does remain because physics still maintains the
    concept of time and that concept still implies
    change, we just need to redefine this change.

    Sorry again for being so jumpy...

    Live long and prosper.
  18. May 14, 2003 #17
    Don't let QM confuse you. Causality is deeper than just usual life experience or apparent behaviour.

    My take on causality is that it has direct correspondence with internal logic of a system. Not necessarily Aristoteles logic we use, but any consistent logic. For eg. Fn=Fn0+1 encodes causality of a sort. Premises are cause of our conclusions.

    In particle world, cause/effect are not easily separable. When particles interact, they have mutual effect on each other, there is no clear cause or clear effect. In face of planck time uncertainty, cause and effect occur simultaneously. Nevertheless, some sort of rules of logic defines the outcome of interaction, and thats causality. If it wasn't so, there would be impossible to observe consistent world, no justification for any conservation laws, any laws. Even though we might be unable to describe particle behaviour, it doesn't mean they behave acausally. Probability distribution has also some cause, however weird it might seem to us.

    I disagree that causality is direct result of time concept, although as always, time has tight ties with anything. Yet time is a beast of its own. Fundamental it is.

    However, one might ponder, what happens if suddenly infront of him most scary devil imaginable appears acausally. Odds are there that one would **** his pants off from fear, which is perfectly causal effect. Basically, any acausal event in our universe will be immediately consumed by causality if it interacts in any way. If it doesn't interact, it does not exist. Any interaction, however weird, is constrained by causality. Therefore, imo, the only acausal event possible is appearance from nowhere or disappearance to nowhere.
    Possible that at fundamental levels acausal events are usual, but any kind of laws would imprint causality to that immediately. We can see only causal world.
  19. May 14, 2003 #18
    Hmmm...let me see about this example.

    Two teams are playing basketball, team A brings it up the floor and passes to another played, while the ball is in the air team B steals it and goes down the court and lays it up. If casuality was true, wouldn't it say that the ball would have changed directions and went down the court and fell in the basket, all on it's own?
  20. May 14, 2003 #19
    You mean "if causality wasn't true", don't you? If causality wasn't true, then yes, the ball may have done that anyway. And yet, we'll never know, because that particular event will only occur once, and that one time, they happened to be doing what they were at the time.
  21. May 14, 2003 #20
    Re: Re: Cause-and-Effect.

    I don't define "time" as synonymous to "causality". "Time" is a dimension.

    And when you said that "'truth' is right up your 'red alert' alley", was that a true statement? :wink:

    No, actually I was hoping to see everyone's opinion about whether it is really true.

    I really hadn't noticed jumpiness.

    Note: I've already attempted to counter the "QM defies Causality" position, in an earlier post. Please respond to my points there, if you disagree with them.
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