Talk:Bucket argument

message: Nothing philosophical here, but the link to Andrew Motte's translation of the Principia doesn't work anymore.
The pdf file can be found here, and a streaming version (quicker to load) there. I don't know which one is better ( maybe both : the stream version inside the article and the pdf for download in the references ?), so i haven't changed anything in the article.
(Feel free to delete this comment from the talk page once the link is fixed !)  — Preceding unsigned comment added by 82.120.215.231 (talk) 09:49, 5 February 2012 (UTC)
thread_title: Link broken

message: I wrote a new article, after reading Newton's Scholium.
I concentrated on the physics, and I avoided the philosophy. Newton's rotating bucket is not situated in empty space; the two globes, connected by a cord under tension had been situated by Newton in otherwise empty space. The bucket argument is not a thought experiment, it is an inference from something seen in daily life; the two-globes-connected-by-a-cord is a thought experiment. It is understandable that the two have been merged into a bucket-with-water-in-empty-space, but I feel the article should be historically correct.
The globes-and-cord thought experiment is by far the most interesting line of thought, it is wider in scope than the rotating bucket argument.
I decided not to write about Mach's philosophical objections against the tacit assumptions in newtonian dyanamics. --Cleon Teunissen | Talk 18:45, 20 Mar 2005 (UTC)
thread_title:  The bucket and the floating globes (new article) 

message: Sebastian (talk) had added Category:Kinematics to the article, commenting:
:maybe should be dynamics, but there is no such cat as of now Sebastian (talk) 10:11, 2005 May 20 (UTC)
The current article on Kinematics opens with:
:In physics, kinematics is the branch of mechanics concerned with the motions of objects without being concerned with the forces that cause the motion. In this latter respect it differs from dynamics, which is concerned with the forces that affect motion.
So the category 'Kinematics' is certainly inappropriate for the bucket argument. The bucket argument is about the philosophy of Classical mechanics. Newton is justifying his concept of laws of motion, he is very much concerned with the forces that are at work. Therefore I have removed the 'Kinematics' category, and replaced it with Category:Classical mechanics <BR>
--Cleon Teunissen | Talk 15:00, 20 July 2005 (UTC)
thread_title:  Category; Classical mechanics 

message: The article proposes:
The use of "it" and "its" which may refer to any of a number of different nouns occurring earlier in the sentence render the meaning obscure. Here are some options:
And so on. Can this sentence be cleared up? It also would be helpful later on to have Descartes' theory as applied to the bucket, so we can see that in fact the bucket experiment contradicts his theory. Brews ohare (talk) 14:11, 12 May 2008 (UTC)
thread_title: Statement of Descartes' position not understandable

message: The text currently has:
Presumably, the concavity of the water shows rotation relative to something else: absolute space. This argument is incomplete, as it limits the participants relevant to the experiment to only the pail and the water, which has not been established. In fact, the concavity of the water clearly involves gravitational attraction, and by implication the Earth also is a participant.
The discussion gets unnecessarily complicated when the traditional setting of the thought experiment is used.  It doesn't help that the "which has not been established" part above does not really make sense.
The earth and its gravity would participate in how the experiment would look -- if run on earth. And the twisted rope would not work unless it were connected to something at the top and being stretched by the earth and the bucket of water from the bottom.  But those factors are just involved because the early writers wanted to make something that could be understood well enough to grasp the essentials.
I've seen a drawing in which the bucket is suspended from a disembodied "hand of God" in an empty universe, but it is presented as a cartoon, not as an attempt to explore the operational factors of the experiment.
The better experiment would put a spaceship through a wormhole into an empty universe (so there is no gravity field from distant stellar objects). Is the spaceship moving? Is it still? There is no meaning to that question. If two spaceships come through and they end up close to each other they may detect that they have a closing velocity with regard to each other. But that gets into another area of the question about whether space is a substance.  
With the one ship it is possible to do experiments with acceleration because the ship still has its rockets. But to make things a little more graphic, let's assume that the rocket engines have gone dead, but the ship has hull-mounted projectile weapons. They aim four equally spaced weapons tangentially to the circumference of the ship. Everything we know about the mysterious "thing" called inertia tells us that crewpersons floating at the center of the ship will see the walls start to spin around them.  But somebody grabbing a handhold on the inner circumference of the hull will experience
the same forces that one experiences riding in a merry-go-round or what the cat in the clothes dryer experiences. (Even one of Schroedinger's. Fame provides no exceptions to inertia.)
In a rotating cylinder, coins ranged side by side around one "great circle" drawn on the hull could be kept in place until jostled or until the stacks got tall enough that there would be no more room for a full complement of coins and there was going to be an overlap. Sooner or later, there would be a stack crash. The dislodged coins would eventually come into contact with the hull at points ranging fore and aft of the original line — slower if in vacuum. As long as the coins and the hull were not frictionless, eventually they would all get accelerated by hull contact and there would be the inevitable "concavity" of the surface of the sea of coins. 
In any experiment there would be a acceleration and there would be rotations (at different velocities) relative to some other things -- the propellant, i.e., the projectiles shot off to start the ship rotating. The words "presumably" and "something else, absolute space" do not have to enter here. Definitely the concavity of the water (at both ends of the water cargo, actually) would show rotation because rotation is acceleration as far as movable components are concerned. The real connection to "absolute space" is probably in the existence of the phenomenon called inertia. 
Inertia seems to be tied in with a very general empirical generalization: Nothing happens unless some force is exerted.  Stones do not jump off mountain peaks. They have to be pushed or dislodged. Asteroids heading straight for collision with earth do not suddenly shear off to avoid a disaster. They have to be pushed or pulled by something. My dirty clothes do not put themselves in the washing machine and flick the switch. No free lunch -- even in an otherwise empty universe, I suspect.
If only one spaceship goes through the wormhole into the empty universe, there is no indication of motion, or of inertia, as long as the spaceship is just floating there.  If, however, the spaceship can split in the middle by firing explosive bolts that are holding two spring-loaded halves together, there is motion. It might turn out to be different, but everything in our experience in this universe tells us that the universe does not work in a magical way.  Is inertia a function of space? Would what we know as inertia change at great distances if it turns out that the universe is not correctly described by Euclidean geometry?  If inertia is primarily a characteristic of the universe, can the universe be given a meaningful account without including something called space? Can the universe and inertia be explained or given a full account if space is interpreted as being only a relationship or set of relationships? P0M (talk) 20:45, 2 July 2008 (UTC)
thread_title:  Traditional version of experiment has some problems that may slow understanding 

message: The section headed Fluid mechanics says:
the parabolic shape applies only for surface regions sufficiently far from the bucket walls, and for water deep enough to keep the surface away from the bucket bottom
The approximate solution actually does not apply all the way to the bucket walls
For a real bucket and a real liquid, the solution near the bucket walls may become quite complicated
This disagrees with An Introduction to Fluid Mechanics & Heat Transfer by J.M.Kay, which says:
In the special case of the forced vortex the fluid is rotating as a solid object
In which case the surface will not be affected by the shape of the bucket.  It will be a paraboloid right up to the edge of the water surface (apart from the meniscus caused by surface tension).  So I suspect that the entire Fluid mechanics section of this article is incorrect.
Occultations (talk) 14:18, 20 April 2010 (UTC)
thread_title:  The effect of the shape of the bucket 

message: This article is titled " bucket argument", which refers to Newton's argument for his point of view; at least it should fairly present that argument, that is, elaborate on it, citing secondary sources that defend it. Instead it only cites secondary sources that dispute that argument and even cites these sources as facts; more POV-pushing than that is hardly possible. Harald88 (talk) 08:23, 9 August 2010 (UTC)
thread_title:  POV marking 

message: I don't believe that this example truly describes absolute motion. I beleive the water would be spinning, but it would be spinning relative to the bucket, wouldn't it?  — Preceding unsigned comment added by MusicAndPhysics (talk • contribs) 01:26, 2 December 2012 (UTC)
thread_title:  Is This Actually Relative?