by zloq » Mon Nov 07, 2011 6:26 pm
The video is meant to demonstrate a *theory* in action. I am talking about the *theory*, quite separate from the experimental difficulties of measuring small, but real, effects. Just because an effect is difficult to measure, or swamped by noise *in a measurement*, it doesn't mean it isn't playing a role.
If I can't measure the change in the velocity of jupiter as a spacecraft goes by, does that mean I should say it doesn't change, or that it is of no consequence? No - I say what theoretical assumptions I am making and I describe the expected effect as delta V even if I don't measure it. You are saying that if something is hard to measure because it is small, it should be regarded as zero - and should be taught to students that it is zero (ugh!). I am saying that some things truly are zero, according to theory, and other things are not. The difference in acceleration of two different masses toward another is expected, by the equivalence principle, to be ZERO. The difference in time to collision, based on Newtonian mechanics, is NONZERO. The difference in velocity of jupiter due to a small spacecraft slingshot is NONZERO.
I am not interested in debating this since I think my description is sound, but if others gained anything from the detail I presented, I welcome postings here. My point has been to provide an accurate theoretical description of what happens when an object falls, and I have heard no criticisms of the theory - in fact an early response was that it was "obvious." I am not lecturing on how science works or something - I am describing the details of how mass does play a role in a falling object in the specific context of this thread and its Newtonian assumptions - in hopes the detail is of interest to some readers here, including those who early in the thread expressed an inkling of puzzlement that the answer, ZERO, didn't seem right.
zloq
The video is meant to demonstrate a *theory* in action. I am talking about the *theory*, quite separate from the experimental difficulties of measuring small, but real, effects. Just because an effect is difficult to measure, or swamped by noise *in a measurement*, it doesn't mean it isn't playing a role.
If I can't measure the change in the velocity of jupiter as a spacecraft goes by, does that mean I should say it doesn't change, or that it is of no consequence? No - I say what theoretical assumptions I am making and I describe the expected effect as delta V even if I don't measure it. You are saying that if something is hard to measure because it is small, it should be regarded as zero - and should be taught to students that it is zero (ugh!). I am saying that some things truly are zero, according to theory, and other things are not. The difference in acceleration of two different masses toward another is expected, by the equivalence principle, to be ZERO. The difference in time to collision, based on Newtonian mechanics, is NONZERO. The difference in velocity of jupiter due to a small spacecraft slingshot is NONZERO.
I am not interested in debating this since I think my description is sound, but if others gained anything from the detail I presented, I welcome postings here. My point has been to provide an accurate theoretical description of what happens when an object falls, and I have heard no criticisms of the theory - in fact an early response was that it was "obvious." I am not lecturing on how science works or something - I am describing the details of how mass does play a role in a falling object in the specific context of this thread and its Newtonian assumptions - in hopes the detail is of interest to some readers here, including those who early in the thread expressed an inkling of puzzlement that the answer, ZERO, didn't seem right.
zloq