# Questions tagged [machs-principle]

Use this tag for Mach's principle. DO NOT USE THIS TAG for the Mach number!

81 questions
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### Questions about an inertial frame

Can someone explain to me what I put in bold? Inertial frame definition: When the coordinate axes are stationary with respect to the mean position of the "fixed" stars or if they move with uniform ...
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### Equation for shape of water drop on hydrophobic surface

What would be the general equation of the 3D shape water forms when it "beads up" on a hydrophobic surface such as wax paper?
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### Mach's principle and centrifugal force

How does Mach's principle explain the centrifugal force as a result of the relative circular motion of the distant stars? Why does this, in the light of Mach's principle, make a net force although the ...
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### How can I interpret or mathematically formalize Maxwellian, Leibnizian, and Machian space-times?

I've been reading the book, World Enough and Space-Time, and I came across a rough list of classical space-times with varying structural significance. Here is the same list, minus Machian Space-time,...
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### Newton's First Law and things that are very old [closed]

Recently I've been revisiting physics text books, and books by Feynman, and others. A curious thought has arisen, while I was reading about Mach's principle, and it seems to gnaw on my mind. I hope ...
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### Black Hole and Mach Principle

In the derivation of the spin–orbit interaction, we transform to a frame that is fixed on the electron. I have several questions about this: Will I see any radiation if I orbit around a static charge?...
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### Is Weinberg wrong in this account of how Mach's principle is incorporated in general relativity?

In his book "Dreams of a final theory" pg.144 Steven Weinberg says "the circulation of the matter of the universe around the zenith seen by observers on a merry-go-round produces a field somewhat ...
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### Do I have to know the General Relativity theory to understand the concept of inertial frame?

I have read answers on this site as well as the Wikipedia article, but they all add to the confusion. Some people suggest that a freely falling frame is an inertial frame. I learnt in classical ...
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### Is MTW's argument in favor of Mach's principle valid?

Looking at older books, I was surprised to see that the general relativity "bible" by Misner, Thorne, and Wheeler is very strongly in favor of Mach's principle, which is treated in section 21.12. ...
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### Feynman-Heaviside formula and Mach's principle

I was wondering if the Feynman-Heaviside formula for the electric field of a moving charge could be used to write down the force/reaction force between charges $q_1$ and $q_2$ in a Machian purely ...
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### What was Newton's idea of absolute space and time?

When one says that Newton believed in the concept of "absolute space" and "absolute time" does it simply mean that the length interval between two points in space and time interval between two events ...
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### Why is Brans-Dicke Theory considered as a failed attempt to incorporate Mach’s principle in a relativistic theory of gravity?

In Generalized Brans-Dicke theory: A dynamical systems analysis by Nandan Roy and Narayan Banerjee, Brans-Dicke theory is described as a failed attempt to incorporate Mach’s principle in a ...
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### Ernst Mach vs. Einstein

In the Ernst Mach wikipedia page, Einstein seems to be influenced by Ernst Mach. But it says In 1930, [Einstein] stated that "it is justified to consider Mach as the precursor of the general theory ...
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### Is rotation absolute? [duplicate]

I was reading an article that rotation instead of linear motion is absolute. Can anyone explain why? Shouldn't an observer (A) moving in a circle around a point in an object that rotates (with respect ...
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### How does an isolated body in deep space 'know' it's rotating? [duplicate]

We can imagine an object floating in the known universe, maximally distant from any other large mass. Maybe it has been there since coalescing after the big bang. What physical phenomena tell it ...
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### How come everything in the universe except the universe itself are spinning? [duplicate]

The planets and stars are spinning, galaxies and clusters are spinning so shouldnt the universe also spin? I think objects spin is to preserve angular momentum but it must also implied that in the ...
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### What is the solution to Newton's bucket problem? [duplicate]

What is the solution to Newton's bucket problem? The Wikipedia page does not give me any finality. After reading, I felt as if the problem implied either one of these two things There is a special ...
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### How does physics know something is spinning or rotating? [duplicate]

From a purely mathematical point of view, as far as I'm aware, there is no difference between rotating a singular point by a phase phi, using its own location as the centre, or rotating all but the ...
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### Can we determine an absolute frame of reference taking into account general relativity?

Given that acceleration induces measurable physical effects, would it be correct to say that there should be an absolute inertial frame of reference? I know that one cannot distinguish a priori ...
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### The Inertial theory of Sciama and an electromagnetic analogue

In 1952 D. W. Sciama introduced a paper On the origin of inertia. It presents a method in which inertia could arise from other mass in the universe. It goes along these lines: If you try to ...
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### How does a spinning object “know” that it is spinning?

I am constructing a thought experiment about a spinning object that is floating in intergalactic space. I assume that this object is about the size of a planet so that it will have enough gravity so ...
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### Differentiating linear and non-linear motion

If there is a Person sitting in a vehicle which is moving, how could he find out whether it's in motion and if he figures that out, how does he find out whether it's accelerated or non-accelerated?
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### Super luminal speed paradox? [duplicate]

Chosing a reference frame in which the Earth is at rest and doesn't rotate is related, but different. Here I'm asking if there is a paradox and if my attempt at resolution has merit, and if not ...
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### Would there be centrifugal force if I were alone in the universe? [duplicate]

When I'm rotating, I feel centrifugal force. But if I were the only one in the universe and rotating, wouldn't I just kinda be still (since I'm not rotating with respect to anything) or would there ...
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### Earth's rotation in an empty universe

I have read these questions: Is rotational motion relative to space? Rotation in an 'empty' universe None of these talk about whether we can and how we can determine rotation of Earth ...
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### Rotation in an 'empty' universe [duplicate]

Possible Duplicate: Is rotational motion relative to space? Assume a universe with the same physics as ours, but containing only one rotating (charge-free) body - let's say the size of the Earth. ...
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### Newton's Bucket, Artificial Gravity, Absolute Rotation, and Mach's Principle

I have been trying to understand how we can talk about absolute rotation in general relativity. I get that it is an area of active debate with some adherents of Mach's Principle and others believing ...
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### To what extent is rotation relative (in GR and other theories)?

In Newtonian physics, rotary motion is absolute even though linear motion is not. More recently, there has been a hope that rotation can also be shown to be relative. Two definitions of relative A ...
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### Chosing a reference frame in which the Earth is at rest and doesn't rotate

We may choose a non-rotating earth as our reference frame and ask ourselves: how about the planetary and stellar motions. A star at a distance of 10 million light years would turn around the earth in ...
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### Mach's principle and infinite speed of distant stars

If rotation was relative, we could say that the Universe is revolving around the earth. But how could this be true, since at some distant point the speed of a star would be greater than the speed of ...
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### Rotational relativity? Is there an universal frame of reference for rotation?

So, there is obviously no such thing as an universal frame of reference for velocity. According to the relativity theory, there is no difference between two observers moving with respect to each other,...
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### Why is angular motion special?

I'm a biochemist, and not a physicist so bear with me if I say something stupid. I do like to read about physics, though and this is one thing I can't wrap my head around. I was recently reading ...
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### Do absolute space and time exist? [duplicate]

Einstein's theory proved that most properties of a body are relative to something and are not absolute. I am still wondering if physicists still think that there is a way that Newton's absolute space ...
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### Atom interferometry,gravity and inertia: What can it measure that light interferometry can't? [closed]

What previously unexplored effects in gravity and inertia can be examined with atom interferometry in ways that hasn't already been done through light interferometry? Can atom interferometry be used ...
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### Massless Electrons and Effect on Graphene Mass

I've read that electrons in graphene can travel masslessly, due to the effect of the graphene crystal around them. I'd also read that the application of an electric field can change this behavior and ...
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### Rotation of our Galaxy's inertial frame

Suppose in the universe, there are inertial frames in the vicinity of galaxies. Suppose also that these frames rotate slightly with respect to each other - that the universe is not quite a 'mill pond'....
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### Can empty space rotate without frame dragging?

A recent question Rotation of our Galaxy's inertial frame is about an observational evidence of the space rotation. My question is if such a rotation is conceptually possible in GR. Can we assume ...
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### Why there is a preference between different reference-bodies?

I know a classical mechanics law points out the following (Newton's first law): material particles with constant velocity will continue to move uniformly in straight line. If material particles are in ...
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### How can Newton's idea of absolute space be reconciled with Galilean relativity?

I wasn't sure if this might be better suited to History of Science and Mathematics SE, but I suppose it is a bit more 'science-y' than historical. Apparently Newton believed in absolute space and ...
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### Will accelerated observer see radiation from the charge that is at rest in observers's frame?

So I had a huge debate about this with my friends. Imagine that you are in a non-inertial frame of reference. For simplicity, assume that frame is accelerated along x-axis. You have held a charge in ...
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### How can you tell if a given reference frame is inertial? [duplicate]

An inertial reference frame is one in which a particle has constant velocity if and only if has a zero net force acting on it. How can one determine if a given reference frame is inertial? For ...
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### Are laws of physics (mechanics) symmetric under uniform rotation?

I'm just starting to learn about symmetry. I understand that physical laws are symmetric under translation and consequently (is it not a consequence?) under uniform velocity in a straight line. I see ...
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### Rotation inside a black hole

As far as I can see most of the questions about rotation of a black hole refer to the appearance of a hole to an outside observer. What about the region within the Schwarzschild radius? According ...
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### Two masses in empty space

Consider two equal point masses which are rotating circular arround each other in empty space for ever (radiation effects are ignored). Let an observer be at the center of mass of the system. Then, ...
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### What's the deal with the gyroscope?

In this article ("The problem with physics", Tony Rothman, ABC science) the author says in the 5$^\textrm{th}$ paragraph: For example, one needs only first-semester equations to describe reasonably ...
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### Question concerning the cause of the rise of water in a spinning bucket in empty space according to Mach

According to Mach we can attribute the fact that in a spinning bucket with water the water rises to the edges of the bucket just as well to the whole Universe rotating around the bucket, as to the ...
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### Would the Earth stop spinning in the absence of stars?

Please explain this in layman's terms. A cosmos without stars would have no spacetime structure relative to which the earth could spin. For there to be gravitational (or inertial) fields capable of ...
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### Is the pressure higher in the corners?

I was watching the video The Ingenious Design of the Aluminum Beverage Can. At 20'', the author says [..] a spherical can [..] has no corner, so no weak points because the pressure in the can ...