Newton's bucket and Galilean relativity

[Hooleehootoo]

I'm re-reading Greene's The Fabric of the Cosmos. He describes Newton as explaining his (Newton's, not Greene's!) thought experiment of the bucket by the existence of absolute space: something with respect to which rotating objects rotate, even in seemingly empty space.

Did Newton ever discuss why rotational motion was absolute, but constant velocity motion was relative? Or did he in fact think all motion was absolute? I guess that would mean he would have predicted that the Michelson-Morley would have found an ether wind.

 

[mijoon]

He thought that time and space, and therefore all motion, was absolute.

 

[Hooleehootoo]

so he thought that when you were on a steadily moving ship and you dropped a coin from your hand, the reason it hit you on the foot was that both you and the ship were moving relative to absolute space?

Did Newton think there were mechanical experiments that could determine absolute motion?

 

[geometer]

so he thought that when you were on a steadily moving ship and you dropped a coin from your hand, the reason it hit you on the foot was that both you and the ship were moving relative to absolute space?

Did Newton think there were mechanical experiments that could determine absolute motion?

I'm not sure I understand your question. If you and the coin are on a steadily moving ship, the coin will drop straight down to the floor below where you held it when you dropped it.

 

[Taoist]

Geometer are you being funny?

Newton took into account velocities but the Lorenz transformation is the theorem that brings the observer into account and each level to predict an absolute K has not been established or verified.

As each article of matter has a relative affect on each other since the constant speed of light reveals a result; the realization of time, our fourth demension, has to be taken into account and to acknowledge the interwoven effect of everything to itself has beautified many explanations.

Has it been thought yet that a negative thereof could simplify dark matter?

 

[GAK]

anyone help me?

i can't understand why Newton had to propose anything to explain the bucket? It seems that he could understand the individule water bits (whatever he wanted to call them) each wanted to proceed in a straight line and upon coliding with the bucket would pile up atop one another.

Why wouldn't he have concluded that? Surely I'm too uneducated to understand.

thanx
jerry

 

[Uglybb]

Greene wasn't dropping the bucket he had it suspended from a rope which you wound up.

The bucket slowly starts spinning to unwind and now look at the reference frames .. look up "bucket argument" in wikipedia.

The problem is the water does not stay level it produces a concave shape.

All observers agree that the surface of rotating water is curved. However, the explanation of this curvature involves centrifugal force for all observers with the exception of a truly stationary observer, who finds the curvature is consistent with the rate of rotation of the water as they observe it, with no need for an additional centrifugal force. Thus, a stationary frame can be identified, and it is not necessary to ask "Stationary with respect to what?":

It leads into the problem of fictional forces (centrifugal force, Coriolis force, and Euler force) what are they pushing on if anything. Once you accept there can be fictional forces it leads directly into General relativity that is gravity is a fictional force quote below from GR in wiki.

In Einstein's theory of general relativity, gravitation is an attribute of curved spacetime instead of being due to a force propagated between bodies. In Einstein's theory, masses distort spacetime in their vicinity, and other particles move in trajectories determined by the geometry of spacetime. The gravitational force is a fictitious force. There is no gravitational acceleration, in that the proper acceleration and hence four-acceleration of objects in free fall are zero. Rather than undergoing an acceleration, objects in free fall travel along straight lines (geodesics) on the curved spacetime.

I think that is the only weak part of the book it never really explains why the bucket is important (in that it defies Newtonian analysis) and he never really brings in fictional forces.

 

[harrylin]

Greene wasn't dropping the bucket he had it suspended from a rope which you wound up.

The bucket slowly starts spinning to unwind and now look at the reference frames .. look up "bucket argument" in wikipedia.

The problem is the water does not stay level it produces a concave shape.

It leads into the problem of fictional forces (centrifugal force, Coriolis force, and Euler force) what are they pushing on if anything. Once you accept there can be fictional forces it leads directly into General relativity that is gravity is a fictional force quote below from GR in wiki.

I think that is the only weak part of the book it never really explains why the bucket is important (in that it defies Newtonian analysis) and he never really brings in fictional forces.

This is an ancient thread
Still it may be useful to give the explanation "straight from the horse's mouth", here:

http://gravitee.tripod.com/definitions.htm

Just press "cancel" and search for "water"; you'll find the discussion near the end of the Scholium.

Harald