Comment on Gravitational force In vacuum video
https://www.youtube.com/watch?v=ybJjYUbGx34
This is nice to see, but it should lead off with where is it, who is involved, how much does it cost to pump the chamber empty, what do they think is still there in the chamber that is causing the feather and ball to fall the same. Lots of other things. Did you record the videos in lossless format? Did you share those videos somewhere so classrooms can study the differences between air friction and vacuum. Did you see the bounce on the feather? That was unexpected. So they have internal tensions and stresses. How do you model and calculate and simulate those? Why did you put solid for the bottom? Sand or something else? How can you record and measure and predict the effects on the ground. How far did the sound travel through the floor? What were the release forces and vibrations in the drop assembly? Were they oscillating during fall from asymmetric release or incidental forces? Is there anyway to see if the motion exactly fits the local gravitational gradients? What was the residual pressure, and how small can the difference between two objects motions be measured and recorded, studied predicted and models calibrated?
How much does it cost to reproduce this? If you did this and only kept pictures for humans to see, it is entertainment mostly and a tiny bit of learning. Record and measure carefully, model and predict and compare, then you are starting to do science and engineering.
Whoever is doing this, perhaps you might think seriously about what measurements could be done in similar situations and facilities. Perhaps go back and challenge those people and others to make a science experiments, not just a public visual demonstration. You did not even measure the local gravity I think. The acceleration is in the motion and the impact. If you put wireless accelerometers and three axis gyros you could get some recordings. How about some thoughtful and creative instrument packages. Raise money for prizes and the best science and engineering teaching and learning. You only have 57 views just now. But I think every single one of the 1.92 Billion first time learners between 5 and 20 in the world will get at least one exposure to “things fall the same rate in vacuum”. And me, at 72, I never saw a decent picture of this my whole life until now. And it seems incomplete because I always associated these things with physics, engineering, mechanics, thermodynamics, gravitation, measurement, modeling and simulation.
Richard K Collins, Director, The Internet Foundation
