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Brian cox got to uses NASA's space power facility the largest vacuum chamber in the world to do Galileo's famous experiment with a heavy weight and a feather ... but you already know the answer

All it takes is to be a TV star to get access to some facilities

If "falling" objects are not falling, and have no force acting on them, why are they influenced by the atmosphere through which they are "not falling"?

Really Bill.S is that a serious question?

If it is I am not going to answer it. You need to work that out for yourself, but let's give you a couple of things to think about.


1.) No-one is saying the ball and feather are not moving. They are simply saying it isn't "falling" as that is defined by layman or more specifically Newtonian physics. Objects moving in air in any direction have wind resistance so that is irrelevant to the argument.

2.) Lets assume there is no such thing as gravity and the earth does not spin. If the experiment was done on the forward facing part of earth which was being accelerated at 9.81m/s would the result be any different? Think about what happens to you when you accelerate a car.

3.) Could you pick the situation 2 from the newtonian belief that a force is pulling you down?

4.) Given all the above how do you tell if you are being accelerated towards the centre of the earth as opposed to being dragged down by some force. Therein lies your problem.

Galileo experiment redone

1.) No-one is saying the ball and feather are not moving they are simply saying it isn't "falling" as that is defined by layman or more specifically Newtonian physics.

How do you define “falling”?

2.) Lets assume there is no such thing as gravity and the earth does not spin. If the experiment was done on the forward facing part of earth which was being accelerated at 9.81m/s would the result be any different? Think about what happens to you when you accelerate a car.

It is my understanding that relativity tells us that any acceleration will influence the outcome, whereas uniform motion, relative to any given object will not.

3.) Could you pick the situation 2 from the newtonian belief that a force is pulling you down?

If by pick you mean distinguish, the answer must be “No”.

4.) Given all the above how do you tell if you are being accelerated towards the centre of the earth as opposed to being dragged down by some force and there in lies your problem?

I see no way I could make that distinction. If I pick up a stone, then drop it, does it fall to earth? If not, I return to my earlier question: “How do you define falling?”

Falling as defined by classical physics is simple

Any movement on an object due to gravity as defined by newtons laws.

Not complicated, you can add direction if it helps understanding like "fall in", "fall down", "fall sideways" and you can even "fall up". The fall down option is the one most of us immediately think of but that like all things human is simply due to familiarity. Some layman and some historic scientists argued that you can't "fall up" so a very long time ago a specific term was created which is "free fall" (http://en.wikipedia.org/wiki/Free_fall). When layman say falling scientists translate it to "free falling" which is the generic case and safe to do.


So there are many things in the universe "free falling" which we would never describe back to a layman as "falling" because they lack the basic understanding, their learning is dictated by what they have experienced.

GR turns that on it's head in that there is "no free falling" you are simply being accelerated because of the distortion of spacetime geodesic. In the clip he substituted that to "falling" because of the target audience and it does not change the meaning or result of the experiment shown.

You are correct you couldn't pick the difference with both theories they are viable options given your data so far.

Both theories predict movement and with movement you encounter wind resistance which will effect the feather more than the bowling ball, that whole mass to surface area thing. So the whole discussion about the air becomes irrelevant and specifically what we are questioning is "Uniform gravitational field without air resistance" hence the need for the vacuum.