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Lightning striking twice?

  1. Mar 17, 2004 #1
    Hi, I'm sure you've had so many of these posts over the time of this board's creation, but alas, I've been having something of a debate with a friend of mine regarding lightning.

    My point is that lightning cannot strike precisely the same point twice because:
    1 - No two things in existence are ever precisely the same. No two bolts of lightning can be the same since the things the causes of the two lightning bolts have to be different. They would only be exactly the same bolt if time-travel was possible.

    2 - Even if the same lightning bolt was caused twice, then the point would have changed. The point that was hit by bolt A couldn't be the same as the point that was hit by point B. The point continually changes through time.

    3 - Even if points 1+2 are somehow proved wrong, we could never know that the same point was hit because we cannot measure anything precisely. The measurements go on forever because obviously you can take the measurement to a further decimal point.


    His argument is that lightning doesn't take into account how it is formed, so theoretically, the same bolt could be re-created, and if a point exists, it can be measured.

    I really think I'm right here, and I'd like it if you could clarify one way or the other. I'm more a philosopher than a scientist so if anyone could tell me any way to make it clearer to my friend that he is wrong would also come in handy.

    Thanks. :)

  2. jcsd
  3. Mar 17, 2004 #2


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    The first problem would be to carefully define what you mean by "same point". Consider a lighting rod. If it works it will be struck many times by lighting, does not that constitute lighting striking in the same place?
  4. Mar 17, 2004 #3
    But would that rod ever be struck in exactly the same point? Would it be struck with exactly the same power? Would the effects it causes be exactly the same in two different strikes?

    I accept that the same tree can be hit twice for example, but not with precisely the same velocity, not at precisely the same point on the tree and not with precisely the same lasting effects.
  5. Mar 17, 2004 #4
    Points are measured in 4 dimensions sometimes, three spatial and the time dimension...so it would have to strike in the same place at the same time. Otherwise it could be argued that since the earth is moving through space, spinning, etc, that it moved and no longer struck it in the same "place".
  6. Mar 17, 2004 #5
    Actually, if a lightning rod system is doing its job the way it was intended then it should never be struck directly. It's job is to bleed the electricity out of the atmosphere before it has a chance to build up. Now we all know that lightning rods do in fact take direct hits. It is just about ALWAYS on the tip when it is a direct hit. Lightning does in fact strike the same place twice. The same way you can get a cold more than once. But they say that you never get the same strain of virus twice because your immune system 'remembers' the virus, or at least up to a point. Same logic.
  7. Mar 17, 2004 #6

    Claude Bile

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    What if a lightning rod were tapered to a very fine point, such as in a Scanning Tunneling Microscope tip? Lightning will be drawn to the tip of the rod, so lightning could strike the same place twice (at least to the precision of about one atomic width).

    Physically, I would regard this as 'the same point', any debate to the contrary would fall into the realm of philosophy, not physics.
  8. Mar 17, 2004 #7
    I think this whole thing sort of started with philosophy/theory - It's the kind of thing I think of a lot.
  9. Mar 17, 2004 #8


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    I think you're nitpicking too much on what "same place" means. There really isn't anything to argue here.
  10. Mar 18, 2004 #9

    Chi Meson

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    Ditto. Same thing can be argue for anything. Are you the same person you were yesterday? A whole buch of your cells have died and been rplaced. After seven years, isn't it true that you havereplaced all your tissue cells?

    How about a river? Is it the same river yesterday as it is today? All of yesterday's water is gone.

    It's fun thought exercise but it is arbitrarily applied to lightning here. Lightning strikes the same "place" regularly. The Empire State buiding gets struck (even with rods) hundreds of times per year. If we argue over "exactly the same point" for macro-world occurrances, then we will never get on in life.
  11. Mar 18, 2004 #10


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    Besides, a lightning bolt can be over an inch in diameter, and they can wander about slightly during a strike. Two bolts striking the sam general area will hit the exact same point.
  12. Mar 20, 2004 #11
    I agree that it is very philosophical, I actually started thinking about this when I studied some stuff by John Locke.

    As I mentioned before, it can strike the same general area, of that I've no doubt. But the area it hits is always to a certain measurement, and in reality, we can't measure anything precisely. Besides, the world isn't this simple. It isn't made up of several different points.

    Oh, and the other side of the argument is that it would have to hit exactly the same point and have exactly the same damage ratio and the amount the bolt would have to wander would have to be exactly the same. For me it's completely inconceivable.

    And we haven't even reached the 'cause & effect' argument yet. Probability doesn't exist, so a lightning bolt either strikes the same point or it doesn't. Whether it could or not is irrelevant. I suppose it's like me saying it's impossible for me to murder someone. If I don't do it, then it was impossible. This is just my fall back argument though. I'm convinced that lightning can't strike the same point twice, even in theory.
  13. Mar 20, 2004 #12
    When someone wins the lottery they might say, "Wow, what were the chances of that happening?" Well the probability of it happening is the same probability of it happening before it was drawn.

    If you look into the future you can predict possible outcomes and give each one a probability of it happening, so the probability of winning the lottery before it is drawn may be 1 in 14 million, after it is drawn the probability of it happening was 1 in 14 million.

    Therefore, if you say, "It's impossible for me to murder someone." Then you are wrong, it is entirely possible, just because you never actually did actually murder someone doesn't mean that it was impossible.
  14. Mar 20, 2004 #13
    I don't agree. Probability comes about because we can't take into account every variable that causes an act.

    In the lottery instance, there isn't a 1/14million chance of winning. If you win it, then it is "fate." We can see why this has happened and realised that it couldn't have happened any other way.

    The reasons why you chose those particular numbers are caused by past experiences or it maybe something simple like those particular numbers caught your eye. It's irrelevent. What matters is that those numbers were chosen, and we can look retrospectively on this choosing of numbers, and apply reasons as to why they were chosen, and then we realise that it was inevitable that you'd choose these numbers, and to choose any other set of numbers would be imossible.

    The same thing applies to the lottery machine which draws the numbers. It is built in a certain way and works in a certain way. It picks out certain balls because it works in a specific way.

    The same applies for the person who puts the balls in the machine. He dropped the balls in the machine in a particular way which allowed the machine to pick out the right balls.

    I'm not saying it's rigged or that anyone is consciously doing this to make the right person win, but there are no random actions taking place. Every action is caused, and it can all be traced back to the Big Bang. We only apply 'chance' and 'probability' (and even free will) because we can't calculate precisely what's going to happen. What we do know is that something WILL happen, and once it does, then we can apply causes and realise that the event couldn't have taken place any other way.
  15. Mar 20, 2004 #14


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    Glynos, by your definitions you could flip a quarter forever and never have it land on the same side twice. Nothing could ever happen twice, why only use lightning?

    If you look at a lightning event, there is some path that will be repeated over and over again. Some ionic path exists in the air and a 'streamer' will go from the ground to the sky. Then, along the same path as the streamer, between 1 to 20 discharges (average is like 4-5 discharges) will happen each lasting less than 1/15,000th of a second.

    So within one lighting strike, we see it as one event but in reality it is most likely 4-5 discharges that follow the ionic path created by the streamer in the first place.

    Lightning researchers shoot a rocket up to clouds with a thin copper wire. The lightning uses the wire as a streamer and it is a nice straight discharge to the same tower.

    Other researchers are going to use a laser to create the ionic conditions to create a path to allow the lightning to follow instead of allowing it to occur randomly.

  16. Mar 23, 2004 #15
    Well it's because the initial argument with my friend was that lightning couldn't strike the same place twice, so I figured I'd ask you lot what you thought.

    Another side of the argument was that the lightning would have to strike the same point and cause precisely the same amount of damage. So, assume we could photograph the strikes as they hit the ground and compare the damage.

    You put one transparant photo over the other, and zoom in on the photos about eight billion, zillion, trillion, to the power of another eight million, on the fringe of the hits. Are you telling me that the amount of damage could still be exactly the same?

    Even if it still looks exactly the same, my point is that (even though we don't have the tools) we can theoretically zoom in further and further and further, until in the end, we will find a difference.
  17. Mar 24, 2004 #16

    We live in three spacial dimensions + time dimension. Nothing can be the same as it would have to happen at exactly the same moment in space-time. Everything is unique for that reason. If were talking about coordiantes, how can it be any other way.

    Let me go further to maybe prove the point. /no pun intended/: Take twins, what makes the slight difference between the two?, conception in space-time is not the same moment, biological factors are in movement. How about a clone?. It seems to me there would be even a greater difference than between twins, because all enviromental factors during its life would have to be duplicated, exactly to match its clone brother, which implies going back in time.
    Last edited: Mar 24, 2004
  18. Mar 24, 2004 #17
    A good way to be more right is try and prove yourself wrong.
  19. Mar 25, 2004 #18

    Parden me, i feel obnoxious today.
    Ok so i admit i am telling a lie, so everything i said is wrong, so now i am right and you have your proof.:wink:
  20. Mar 26, 2004 #19
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