Questions tagged [machs-principle]

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Thought experiment in Mach's principle - Can a void universe be considered with special relativity?

Mach's principle is based on a thought experiment in which an astronaut floats in the middle of a space devoid of all matter and all landmarks. No star, no source of energy is present, whatever the ...
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Non-inertial frame and Newton's First and Second laws

The Newton's First law claim that in the absence of forces, a particle moves with constant velocity $v$. The Newton's Second Law claims that for any particle of mass $m$, the net force $F$ on the ...
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6 answers
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How to affirm whether a frame of reference is Inertial or non-inertial?

As far as I know, inertial frame of reference are the ones where the all the three Newton's laws of motion hold. Having this definition we can then identify all such frames of reference which are ...
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4 votes
7 answers
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Will a planet rotate if it is the only being in the universe? [closed]

As a senior student , I have been wondering whatever the word inertia mean . Is inertia lying in the interaction between all the objects , or is it the nature of a space even without anything put into ...
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Any connection between Mach's Principle and quantum entanglement?

Mach's Principle posits that the inertia of an object is determined by its interactions with all the other objects in the universe, even those at a very great distance. In the words of Hawking and ...
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Why COM/point frame (Space/Body) is not considered to be rotatory frame as well? Like when asks for angular momentum of a system about a point?

Lets consider this: Imagine the situation where a disc is rolling and also spinning about a point on ground (rolling without slipping) if someone asks to tell whats the angular momentum of disc about ...
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Why does the classic textbook by Goldstein say that distant galaxies are inertial reference frames?

Why does pp 2 of the classic textbook by Goldstein say that distant galaxies is inertial reference system in the context of the mechanics of astronomical bodies? How could we identify an inertial ...
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What is the symmetry group of Mach's spacetime?

Newtonian spacetime can be modeled as a geometric object $M$ (affine space or manifold with connection with an absolute time function etc. etc.) that is symmetric under the action of the Galilean ...
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What is Shape dynamics?

From Wikipedia: In theoretical physics, shape dynamics is a theory of gravity that implements Mach's principle. In General relativity curvature of Spacetime causes gravity, in String theory it is ...
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12 votes
2 answers
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Very strange published papers on Mach's Principle

I have recently come across a set of peer-reviewed conference papers (https://petermarkjansson.com/research/machs-principle/) reporting observations of electromagnetic markers of Mach's Principle. In ...
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7 votes
3 answers
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Is General Relativity compatible with Mach's Principle?

Einstein proposed what he called Mach's Principle. For the purposes of this question can we define Mach's Principle as being that e.g. if a bucket suspended by a rope contains water riding up on the ...
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What makes the inertial reference frames special?

What makes the inertial reference frames (IRFs) special? Specifically: Using inertial reference frames is a matter of computational convenience, but in principle we could build physics without using ...
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Mach's principle and a reference frame for acceleration

Although there are different statements of Mach's principle, one statement could be that acceleration is meaningless unless it can be defined relative to something. The distance stars provide a fixed ...
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Isn't Unruh effect against the equivalence principle?

Doesn't the Unruh effect violate EP? Since the temperature of an absolutely accelerating reference frame would be different from an inertial one according to this effect, then one finds a criterion to ...
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1 answer
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The definition of inertia in Mach's principle

Can anyone please explain me Mach's principle, i.e the definition of inertia he has given? I am really not getting what spin and universe have to do with inertia because what we are taught in our ...
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3 votes
1 answer
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Is inertia still considered a mysterious force?

When I first saw, for example, weightless objects in a space capsule, I assumed that pushing them would require no effort because, of course, they did not weigh anything. On Earth, heavy objects are ...
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How well can we measure how fast are we spinning?

Although absolute translational motion is meaningless and unmeasurable (Michelson and Morley, etc), absolute rotational motion is meaningful (Newton's bucket) and measurable, using Foucault's pendulum....
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Centrifugal force of static observer at North Pole

This question is somehow related to Newton's bucket and absolute rotation concepts, but applied to a simple, tangible scenario. Let's suppose I could hover over the North Pole, and "detach" ...
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4 votes
2 answers
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How do I know if I'm spinning?

Clearly, if I'm spinning, I'll feel my arms lift away from my torso. But what sets the preferred angular momentum? Is there a preferred angular momentum in a vacuum? In Newtonian mechanics, I imagine ...
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1 vote
1 answer
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Mach's Principle and spin angular momentum

According to Mach's Principle, angular momentum (as in the Newton bucket experiment) is relative to the overall mass distribution of the universe, or perhaps some other characteristic of the universe'...
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Mach's conjecture and the twin paradox in an empty universe

What would happen if we revisit the twin paradox in an empty universe? Indeed, according to Mach's principle, when a spaceship accelerates in our universe filled with too many stars and other objects, ...
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What is centrifugal force relative to? [duplicate]

Edit- the answer is mach's principle and mach's principle is sketchy so there is no good answer. So I understand that centrifugal force is really just inertia and stuff but I still have a question. ...
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2 votes
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Would Doubly Special Relativity or Mach's Principle allow faster-than-light travel to occur without violating causality?

Doubly Special Relativity posits that the Planck length is the same in all reference frames. Mach's Principle posits inertia is produced by the combined mass of the universe. From my limited ...
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Does General Relativity actually satisfy the General Principle of Relativity?

The “General Principle of Relativity” being “All systems of reference are equivalent with respect to the formulation of the fundamental laws of physics”. To my knowledge, this is related historically ...
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1 vote
2 answers
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How does an isolated observer know if they're accelerating?

I'm aware of this question and read its answers, but I'm not sure if it specifically addresses what I want to ask, and also it'd be nice to have a more accessible answer since I don't know GR. I'm ...
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1 vote
1 answer
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How does an isolated electron in deep space 'know' it is spinning? [duplicate]

This is a question about Mach's principle. Why is Mach's principle still an open question? In particular, if inertia arises from distant matter, Mach's principle raises the question would a particle ...
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Would an astronaut, alone in space with no reference point, get dizzy? [duplicate]

I’m not quite sure of the biology behind it, but for my question let’s assume that spinning of any kind would cause dizziness as a more dense object would sink to the outside of the body showing that ...
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7 votes
3 answers
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Is all motion relative in general relativity?

I was reading up on Mach’s principle and the historical relation it had with the development of General Relativity. As I understand it, one formulation of Mach’s principle states that for all motion ...
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2 votes
1 answer
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Understanding Mach Principle

I cannot get the essence of Mach's Principle. In my undestanding, it states that the cause of the so-called "fictitious forces" which arise in non-uniform motion has to be found in the relative ...
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0 votes
0 answers
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Grasping (Inertial) Frames of Reference [duplicate]

I am new to studying Special Relativity and have some trouble truly understanding what the phrase (Frame of Reference) tries to imply. So I understand that an inertial frame of reference, for example,...
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9 votes
6 answers
3k views

How can we tell if the Earth is spinning without any external references? [duplicate]

The rotation of the Earth about its axis makes it bulge at the equator and contract at the poles due to the centrifugal forces. How do we know, without any external references, that the Earth is ...
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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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1 vote
1 answer
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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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1 vote
2 answers
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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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2 votes
0 answers
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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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17 votes
3 answers
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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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11 votes
1 answer
383 views

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 ...
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1 answer
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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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5 votes
2 answers
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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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4 answers
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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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0 votes
0 answers
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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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2 votes
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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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9 votes
3 answers
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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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38 votes
9 answers
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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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0 votes
1 answer
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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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-2 votes
1 answer
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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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28 votes
4 answers
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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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4 votes
3 answers
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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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5 votes
1 answer
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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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1 vote
0 answers
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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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