- #1
davee123
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So, I'm sure many of you have seen the experiment recently by a flat-Earth member who brought a level on a plane with him in order to determine whether or not the Earth is flat or round. And yeah, my immediate thought was similarly "how silly!" But it did make me wonder: Could you do it that way?
In addition to acting as a "level" to tell if surfaces are perpendicular to the pull of gravity, a level can (I believe) also be used as a makeshift accelerometer. If you're accelerating forwards, the liquid in the vial should move backwards, pushing the bubble forwards-- and then it should even out when you reach a constant velocity.
But since (when traveling in a circle around the Earth), you'd be changing your acceleration constantly, what would the effect be on the bubble?
Hence, the "correct" way (I think) to conduct the experiment would be to make sure the level was flat before takeoff and keep it in that position for the duration of the flight. Then, when the plane evens out at its cruising altitude and speed (presuming it maintains both constantly), if the bubble is positioned forwards, then there's centripetal force (and a curved Earth), and if the bubble's in the exact same place as before, there's no centripetal force (a flat Earth). (Obviously, you'd want to account for turbulence, perhaps averaging the bubble's position over the course of 10 minutes, say)
Of course, the particulars are where I think this method (as currently described) is useless. My rough guess is that at 500mph, and a mass of about 1g for the liquid, you'd get on the order of 0.000007841 Newtons of force on the liquid in the level, which (I'm guessing?) is way too small to detect. At that scale, would the liquid's viscosity or the effects of surface tension against the tube cancel out any change at all? Would you need laser precision to detect the difference in the position of the bubble? Could you use a longer (or straighter) tube or a more dense liquid to make the difference detectable to the human eye? Could this experiment be used to prove the Earth's curvature?
Other considerations I'm missing?
DaveE
In addition to acting as a "level" to tell if surfaces are perpendicular to the pull of gravity, a level can (I believe) also be used as a makeshift accelerometer. If you're accelerating forwards, the liquid in the vial should move backwards, pushing the bubble forwards-- and then it should even out when you reach a constant velocity.
But since (when traveling in a circle around the Earth), you'd be changing your acceleration constantly, what would the effect be on the bubble?
Hence, the "correct" way (I think) to conduct the experiment would be to make sure the level was flat before takeoff and keep it in that position for the duration of the flight. Then, when the plane evens out at its cruising altitude and speed (presuming it maintains both constantly), if the bubble is positioned forwards, then there's centripetal force (and a curved Earth), and if the bubble's in the exact same place as before, there's no centripetal force (a flat Earth). (Obviously, you'd want to account for turbulence, perhaps averaging the bubble's position over the course of 10 minutes, say)
Of course, the particulars are where I think this method (as currently described) is useless. My rough guess is that at 500mph, and a mass of about 1g for the liquid, you'd get on the order of 0.000007841 Newtons of force on the liquid in the level, which (I'm guessing?) is way too small to detect. At that scale, would the liquid's viscosity or the effects of surface tension against the tube cancel out any change at all? Would you need laser precision to detect the difference in the position of the bubble? Could you use a longer (or straighter) tube or a more dense liquid to make the difference detectable to the human eye? Could this experiment be used to prove the Earth's curvature?
Other considerations I'm missing?
DaveE