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16 votes
2 answers
2k views

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 ...
Meep's user avatar
  • 4,067
14 votes
2 answers
5k views

Why the Galileo transformation are written like this in Quantum Mechanics?

In Quantum Mechanics it is said that the Galileo transformation $$\hat{\mathbf{r}}\mapsto \hat{\mathbf{r}}-\mathbf{v}t\quad \text{and}\quad \hat{\mathbf{p}}\mapsto \hat{\mathbf{p}}-m\mathbf{v}\tag{1}...
Gold's user avatar
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11 votes
2 answers
1k views

Do Newton's laws of motion imply no physical difference between different inertial frames of reference?

I'm a mathematician learning physics from scratch, for my own curiosity and interest. Starting from the basics, I'm trying to get a deep grasp of Newton's laws of motion. V.I. Arnold describes Galileo'...
35T41's user avatar
  • 404
7 votes
6 answers
2k views

Is kinetic energy relative or absolute? [duplicate]

I only can think of kinetic energy as absolute. I know velocity is relative but I can't see kinetic energy as being relative because that would violate energy conservation. For example, if in some ...
yass_the1's user avatar
7 votes
3 answers
4k views

Why are forces independent from the frame of reference?

The following question occurred to me while reading a proof of the following statement: If K is an inertial frame of reference, then a K’ frame of reference, which is moving with a constant ...
naroslife's user avatar
6 votes
1 answer
1k views

How could any frame of reference be inertial?

The image below shows that a bystander watching the merry-go-round is in an inertial frame of reference. However, to nitpick, wouldn't the observer still be accelerating because it's on Earth?
joshua mason's user avatar
6 votes
3 answers
855 views

How can a Physical law not be invariant?

In Relativity, both the old Galilean theory or Einstein's Special Relativity, one of the most important things is the discussion of whether or not physical laws are invariant. Einstein's theory then ...
Gold's user avatar
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6 votes
6 answers
7k views

Inertial Frames of Reference - Inertial vs. Accelerated Frames

According to Robert Resnick's book "Introduction to Special Relativity", a line states the following as the definition of an inertial frame of reference: "We define an inertial system as a frame of ...
Ram Sidharth's user avatar
4 votes
9 answers
3k views

Suppose you are in a closed box which is in motion [duplicate]

Suppose you are inside a closed box which is moving with a constant speed with no acceleration whatsoever. You cannot see outside the box. If you are given all the instruments you need, what ...
Amadeus's user avatar
  • 205
4 votes
1 answer
427 views

Galilean invariance in Electromagnetism

Griffith's Introduction to Electrodynamics when introducing Faraday's Law, considers two scenarios: Moving loop on a magnetic field. Current flows due to the motional EMF. The same scenario but on ...
Gilgamesh's user avatar
  • 825
4 votes
0 answers
103 views

Why do Galilean transformations change both states and operators?

When a Galilean transformation on a quantum system is performed, the states and the operators change: $$|\phi\rangle \rightarrow |\phi\rangle'$$ $$\hat A \rightarrow \hat A'$$ I don't understand the ...
SimoBartz's user avatar
  • 1,978
3 votes
5 answers
182 views

Why isn't the idea of an inertial frame relative? [closed]

I truly apologise if this has been asked to death somewhere, I imagine it has, but I'm yet to find an answer that completely satisfies me. In short, I don't see why our chosen inertial frames are &...
TheInquisitiveOne's user avatar
3 votes
3 answers
850 views

Does Galilean relativity constitute a dynamical symmetry or an isometry?

There are many papers which derive the form of the Lorentz transform from elementary symmetry principles (usually homogeneity of spacetime, isotropy of space, and the fact that boosts form a group), e....
EtaZetaTheta's user avatar
  • 1,511
3 votes
1 answer
89 views

The principle of relativity and why Inertial frames attribute the same velocity to one another

In introductory texts introducing relativity, it is always assumed that frames measure the same velocity for each other. For example if frame S' moves at velocity v with respect to respect, then S ...
Talha Ashraf's user avatar
3 votes
1 answer
1k views

Can we really not tell if we are moving?

It has been a while since I've thought about physics, however, I remember something about how if you are on a train with no windows that is going perfectly straight and is perfectly smooth, there is ...
CumminUp07's user avatar
3 votes
1 answer
294 views

Why isn't time reversal a Galilean transformation?

I'm a mathematician learning physics from scratch, starting from Newtonian mechanics. As far as I understand, Galilean transformations are defined as transformations of space-time that transform from ...
35T41's user avatar
  • 404
3 votes
1 answer
102 views

Prerelativity physics, Special Relativity, and General Relativity formalisms summary [closed]

In order this have a better understanding of "the big picture", a tried to do the following summary, but I can't really complete it for GR. This based on the introduction chapter of Wald's ...
xpsf's user avatar
  • 1,074
2 votes
5 answers
132 views

If motion relative to a frame of reference is purely relative, how do we account for the work done to move relative to the frame of reference?

I get the idea that everything is in motion, and there's no absolute reference frame for everything. But when we consider local events, like a train passing through a town, I have trouble accepting ...
Justin Palmer's user avatar
2 votes
2 answers
255 views

Unlike rotation, why a $3\times 3$ translation matrix cannot be written in 3D? or can it be?

The effect of rotation in 3d on a vector, $\vec{r}=x\hat{x}=y\hat{y}+z\hat{z}$ is given in the form a matrix product:$$\vec{r}\to O\vec{r}$$ where $O$ is a $3\times3$ proper orthogonal matrix. Can we ...
Solidification's user avatar
2 votes
5 answers
196 views

Violation of Newton's second law if the mass if changing?

I learned some thing called Galilean principle of relativity which says that two inertial frames are equivalent and the laws of physics are the same in both inertial frames. However here comes the ...
Bruce M's user avatar
  • 421
2 votes
1 answer
69 views

What is actually meant when it is said Scalar is invariant?

As far as i know a quantity is called invariant if it satisfies some specific transformations. Now,Suppose a body is moving with velocity $\vec{v}$ as measured from the lab frame.Its non-relativistic ...
Manas Dogra's user avatar
  • 1,108
2 votes
2 answers
709 views

Confused on Newton's second law being invariant under relativity

I am a math student with some interests in physics. I picked up a book called "A First Course in General Relativity", and I am confused on the second page. I am assuming by notation or convention. ...
Ssaug's user avatar
  • 23
2 votes
2 answers
266 views

Inertial frames as in Landau & Lifshhitz mechanics 1st chapter

If we see inertial frames from a basic point of view (precisely more basic axiom from which I can at least derive the law of free body as in landau mechanics first chapter) that inertial frames are ...
Ashley Chraya's user avatar
2 votes
2 answers
607 views

Galilean transformations of velocity

If I perform a Galilean boost $$x' = x - vt \\ t'=t$$ between two frames $S$ and $S'$, observers in each frame would disagree on the velocity of a particle because $$ \frac{dx'}{dt'} = \frac{dx}{dt} -...
Hermitian_hermit's user avatar
2 votes
3 answers
1k views

Is the assumption that the two reference frames be inertial required in the derivation of transformation equations?

In the derivation of Galilean transformations the only assumption is that the two frames are moving with some uniform relative velocity $u$. Suppose with respect to some inertial frame $O$ the two ...
Ron's user avatar
  • 532
2 votes
3 answers
75 views

If an observer was trapped in a closed box with no way to interact with the external surroundings how will he know if he is moving or at rest [duplicate]

I am a high-school student. Recently we learned the concepts of relative motion and velocity. The idea that anything in motion can subsequently be at rest depending on the frame of reference ...
AMAL's user avatar
  • 21
2 votes
0 answers
136 views

Principle of relativity and Galileo's group

A doubt has arisen for me about the principle of relativity, and being such a fundamental subject I think it only fair to try and clarify it. The following line of reasoning was presented to me in a ...
Bml's user avatar
  • 1,723
2 votes
0 answers
125 views

Why did Feynman tell "we cannot locate earth's angular position, but we can tell that it is changing"?

I was reading "Symmetry in physics" by Feynman, where he wrote: If we perform sufficiently delicate experiments, we can tell that the earth is rotating, but not that it had rotated. In other words, ...
user avatar
2 votes
0 answers
444 views

Question about Origins in Galilean transformation

I'm just learning about relativity, and every equation I see for a galilean transformation of frame $S'$ (moving with uniform velocity in the $x$-direction with respect to frame $S$) is $x'=x-vt$, $y'=...
user153582's user avatar
1 vote
2 answers
1k views

What does a Galilean transformation actually mean?

What does a Galilean transformation actually mean? I'm having trouble defining the equation for displacement shifts $x'=x-vt$. Does it mean that to any event $C$ the displacement in the primed ...
user avatar
1 vote
2 answers
210 views

Is it always possible for an observer to realize to be in a non-inertial frame?

Galilean relativity principle states that two frames moving with uniform linear motion cannot be distinguished. But is it always possible to realize to be in a non-inertial frame? In a rotating frame ...
Sørën's user avatar
  • 2,637
1 vote
2 answers
87 views

Wave hits beach-example: Does sweeping crest constitute a Frame of Reference?

A long wave rolls in at 1 m/s and hits an almost parallel beach. It's 900k km long, and hits the beach at .1 micro degrees. Basic math tells us the crest of the wave rides down the beach at a speed of ...
harry's user avatar
  • 290
1 vote
1 answer
93 views

Galilean relativity in terms of homogenity for car example

I have a question related to Landau & Lifshitz's book. In that, he says: If we were to choose an arbitrary frame of reference, space would be inhomogeneous and anisotropic. This means that, even ...
Giorgi's user avatar
  • 535
1 vote
2 answers
97 views

Is clause "distance doesn't depend on frame of reference" an axiom in Newtonian Mechanics?

Consider 2 object is 1 and 2, at time t1: 1 has position is C and 2 has position is A. In frame of reference 1 (1 is stand still), from time t1 to time t2, 2 moves from A to B In frame of reference 2 ...
newbieatphysics's user avatar
1 vote
2 answers
305 views

Contradiction between Galilean transformation and conservation of mechanical energy

Consider the system described by the above diagram. The table is frictionless and the string and the pulley are massless. Suppose that at heights $h$ and $\widetilde{h}$ of $m_2$ the corresponding ...
Brain Stroke Patient's user avatar
1 vote
4 answers
234 views

Reference frame doubts about isotropy

Landau & Lifshitz on p.5 in their "Mechanics" book states the following: ...a frame of reference can always be chosen in which space is homogeneous and isotropic and time is homogeneous....
Giorgi Lagidze's user avatar
1 vote
3 answers
122 views

Law's of Mechanics are Galilean invariant

In my current physics book one line reads: "The laws of mechanics are Galilean invariant.", with corollary: "No mechanical experiment can be used to tell whether an inertial frame is ...
Pim Laeven's user avatar
1 vote
1 answer
441 views

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,...
The victorious truther's user avatar
1 vote
2 answers
1k views

Confusion about momentum in an inertial reference frame?

In my notes, it says that the total change in momentum of an inertial reference frame is zero. Please see the picture below This has confused be because I nnderstand that the inertial reference ...
Meep's user avatar
  • 4,067
1 vote
1 answer
77 views

Principle of Relativity and the invariance of Newton's law in IRFs

Newton's law are form invariant under the coordinate substitutions: $$ \tilde{x^{i}}=x^{i}+a^{i} $$ This means that Newtons' equation of motion, $$ F^{i}=m \frac{d^{2} x^{i}}{d t^{2}} $$ (where $i=1,2,...
HRTninja's user avatar
1 vote
0 answers
142 views

Assumptions in Galilean and Relativistic Frame Transformation

While deriving the frame transformation equations, either the Galilean Transformation or Lorentz transformation. I have seen almost all authors mentioning/assuming that if an inertial frame $\textbf{S}...
Gaurang Agrawal's user avatar
1 vote
2 answers
539 views

Power in different reference frames

I would like to reopen the question asked in this post because I am not quite satisfied with the accepted answer. Imagine observer A stationary (in world reference frame) and observer B moving with ...
Luka Mandić's user avatar
0 votes
2 answers
304 views

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 ...
Bibek_G's user avatar
  • 223
0 votes
3 answers
94 views

Is the surface of Earth a global inertial frame?

I understand that a reference frame attached to an observer standing on the surface of non-rotating Earth is not a locally inertial frame but I wonder it can taken as a globally inertial frame because ...
weeab00's user avatar
  • 711
0 votes
1 answer
86 views

Velocity addition as a special case of change of reference frame

In this question, I want to restrict the discussion to classical mechanics as understood before 1900; that is, to exclude any discussion of relativity (however, if there is a neat generalization I ...
EE18's user avatar
  • 1,261
0 votes
1 answer
211 views

In space I am moving wrt to what?

Let us suppose I am running on a street. When my eyes are open, I can see many things moving backward, and thus it gives me an idea that I am moving wrt those things. Not even this, even if I close my ...
gpuguy's user avatar
  • 823
0 votes
2 answers
753 views

Inertial and non-inertial frames of references

I've heard from a physics professor that there's no stationary platform to observe and analyze a body in motion. Why did he mention that? Is it because even seemingly stationary objects like a parked ...
alok's user avatar
  • 472
0 votes
1 answer
66 views

Center of Mass and Systems of Particles in Galilean relativity

Consider a reference frame in which two particles move with constant velocities $\vec{v}_1 = v_1 \hat{i}$ and $\vec{v}_2 = -v_2 \hat{i}$. Their center of mass would be the vector $\vec{R} = \frac{(...
EM_1's user avatar
  • 910
0 votes
3 answers
119 views

Why is it that a vertically thrown ball will move horizontally if we are travelling in a non-inertial reference frame?

If I throw a ball vertically inside a moving train, there will be horizontal movement if the train accelerates/decelerates (ie is not an IRF) and no horizontal movement if it does not (ie is an IRF). ...
tom894's user avatar
  • 187
0 votes
1 answer
436 views

Galilean Transformations Derivation

I'm trying to understand the Galilean Transformations, as shown in my book. Here's the situation, first and foremost: Two observers, R (uses Roman Coordinates for its Reference Frame) & G (uses ...
DarkRunner's user avatar