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Jagella
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I was recently thinking about the Heisenberg Uncertainty Principle which states that we can not know a subatomic particle's position and momentum at any instant. We can know one or the other measure but not both at the same time. The more we know about one, the less we know about the other.
Can this same principle apply to macro objects like bowling balls? If we wish to know a bowling balls' average velocity, we measure the time it takes to roll down the alley to the pins and divide that number into the length of the alley. Obviously, we know little about the ball's position, though, because it moved down the entire length of the alley. We can consider the first half of the alley and measure the average velocity of the ball down that distance. Doing so reduces the uncertainty of the ball's position by one-half, but now we know only one-half about the ball's average velocity because we are not measuring the ball's velocity down the entire alley, only one-half of the alley.
It seems to me that the measurement of average velocity and position are what Bohr would call "complimentary" measurements. When one measurement increases in accuracy, the other decreases in accuracy.
An obvious objection might be raised at this point. We can apply Newton's laws of motion and basic differential calculus to determine the ball's instantaneous velocity at any position along its path down the alley. We then would know its exact position and velocity.
Does this argument demonstrate that Heisenberg's Uncertainty Principle does not work on the macro level? I believe that what measurements we may make on the macro level are only approximations, and therefore we really don't know the bowling ball's exact position and velocity. The ball has substantial volume and is made up of trillions of atoms. What point in the volume of the ball can we refer to when we consider its position? Classical physics is fine for making approximate measurements on the macro level, and it makes some sense to speak of simultaneous position and velocity for practical purposes. If we zoom down to the level of atoms, though, experiments demonstrate that the greater precision begins to show that measuring a particle's position precludes measuring its momentum, and vice versa.
What I'm wondering is just how do experiments demonstrate Heisenberg's Uncertainty Principle. Can anybody help me with this issue?
Jagella
Can this same principle apply to macro objects like bowling balls? If we wish to know a bowling balls' average velocity, we measure the time it takes to roll down the alley to the pins and divide that number into the length of the alley. Obviously, we know little about the ball's position, though, because it moved down the entire length of the alley. We can consider the first half of the alley and measure the average velocity of the ball down that distance. Doing so reduces the uncertainty of the ball's position by one-half, but now we know only one-half about the ball's average velocity because we are not measuring the ball's velocity down the entire alley, only one-half of the alley.
It seems to me that the measurement of average velocity and position are what Bohr would call "complimentary" measurements. When one measurement increases in accuracy, the other decreases in accuracy.
An obvious objection might be raised at this point. We can apply Newton's laws of motion and basic differential calculus to determine the ball's instantaneous velocity at any position along its path down the alley. We then would know its exact position and velocity.
Does this argument demonstrate that Heisenberg's Uncertainty Principle does not work on the macro level? I believe that what measurements we may make on the macro level are only approximations, and therefore we really don't know the bowling ball's exact position and velocity. The ball has substantial volume and is made up of trillions of atoms. What point in the volume of the ball can we refer to when we consider its position? Classical physics is fine for making approximate measurements on the macro level, and it makes some sense to speak of simultaneous position and velocity for practical purposes. If we zoom down to the level of atoms, though, experiments demonstrate that the greater precision begins to show that measuring a particle's position precludes measuring its momentum, and vice versa.
What I'm wondering is just how do experiments demonstrate Heisenberg's Uncertainty Principle. Can anybody help me with this issue?
Jagella