What is principle of relativity: Definition and 38 Discussions

In physics, the principle of relativity is the requirement that the equations describing the laws of physics have the same form in all admissible frames of reference.
For example, in the framework of special relativity the Maxwell equations have the same form in all inertial frames of reference. In the framework of general relativity the Maxwell equations or the Einstein field equations have the same form in arbitrary frames of reference.
Several principles of relativity have been successfully applied throughout science, whether implicitly (as in Newtonian mechanics) or explicitly (as in Albert Einstein's special relativity and general relativity).

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  1. HighPhy

    I 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 lecture, but is it really correct? It seems very unstable to me. Take two frames of reference...
  2. A

    B The synchronization of clocks and the relativity of motion

    In his thought experiment on the relativity of simultaneity, Einstein synchronizes two clocks A and B (at either end of a rod) to the clock C in a stationary frame, while A and B (the rod) is moving relative to C. The equations Einstein finishes with demonstrate how observers moving with A and...
  3. A

    B Principle of Relativity: Classical Physics Example

    hi everyone "The principle of relativity: The laws of physics are the same in all inertial reference frames." Is in classical physics The laws of physics aren't the same in all inertial reference frames!? Give an example in classical physics Thanks
  4. cianfa72

    I Principle of relativity for proper accelerating frame of reference

    Hi, I've a doubt about the application of the principle of relativity as follows. Assume as principle of relativity the following statement: It is impossible by any experiment performed inside a "closed" laboratory to say whether we are moving at constant velocity or staying at rest. Consider...
  5. cianfa72

    I Principle of relativity: active vs passive point of view

    Hi, starting from this thread I'm a bit confused about the content of the principle of relativity from a mathematical point of view. Basically the "Galilean principle of Relativity" puts requirements on the transformation laws between Inertial Frame of Reference (IFR); thus they have to...
  6. BruceAW

    I Apparent Violations of Principle of Relativity?

    I have for a long time been pondering the concept of 'Absolute velocity'. Or, 'Proper motion'. The velocity of an object, with respect to the center of mass of the universe, and the cosmic microwave background radiation. Ways, it seems to make more sense, than merely relative velocities, with no...
  7. H

    B Maxwell's EM Theory vs Principle of Relativity

    What was the problem between Maxwell's EM theory and the principle of relativity? Why went the theory against the principle? I understand that the EM theory says that Light was a wave and ether is it's medium. On the other hand the principle of relativity says that there is no state of...
  8. F

    I Questions about the general principle of relativity

    One of the founding principles in GR is the principle of general relativity, which loosely states that all coordinate frames (inertial and non-inertial) are equivalent in the sense that the laws of physics are invariant. My question is, does the justification for this come from Einstein's...
  9. S

    I Applying the Principle of Relativity to Quantum Mechanics

    I read the forum rules, I hope I am not breaking them as these principle is generally accepted and I am not contradicting mainstream science. "The principle of relativity, according to which the laws of physical phenomena should be the same, whether for an observer fixed, or for an observer...
  10. Pushoam

    I Is the Principle of Relativity different for different theories?

    The images have been taken from the section : Relativity according to Galileo and Newton, page no.66, special relativity , A.P.French,1968What I understood is: According to the first paragraph, Laws of transformation are needed so that a theory which describes a phenomenon w.r.t. one reference...
  11. J

    Principle of relativity and invariance of c

    First postulate (principle of relativity) and 2. Second postulate (invariance of c), affect not we continue investigating new things?
  12. R

    Galilean principle of relativity

    Galilean principle of relativity is for sure not absolutely true, isn't it? Say one has a pool full of water within a spaceship, if the spaceship is accelerated and then acceleration stops, one can look at the ripples in the pool, analyze their form and then tell, up to a certain degree of...
  13. K

    Principle of relativity hypothetical question

    Ok, so I have had a lot of spare time and started pondering the things of the universe. Mainly problems looking at time dilation, mass dilation, length dilation and gravity. So one day I came up with a question that I have been unable to answer and I wonder if it is answerable or if there are...
  14. W

    Galilean principle of relativity and Gödel's incompleteness theorems

    Here is a question, that is so many levels above my analytical, logical, mathematical and physics skills (which sum up, in my case, to no more than popular science and science fiction reading), so the only reason that i am still asking this question, is that, not asking a question, seems to me...
  15. A

    Regarding arguments in favor of Principle of Relativity

    hello.. I am reading "Relativity, the Special and The General theory of relativity by A. Einstein", and i have a few doubts that i wish to clarify. In one of the section there are two arguments given in favor of the principle of Relativity,one being that laws of classical mechanics apply...
  16. D

    Generalizing the special principle of relativity?

    I usually read the (special) principle of relativity stated along the lines of: "the laws of physics take the same form in all inertial reference frames". Here's my question: can we generalize this by saying that the laws of physics take in same form in any two reference frames-- perhaps...
  17. C

    Principle of relativity, covariance and physical law.

    Hi! I'm studying special relativity and relativistic dynamics and I'm struggeling a little bit with the concept of 'covariance' of physical equations. As far as I understand so far 'covariance' is related to the 'form invariance' of the equations of motions in relativity and the concept is...
  18. U

    Is Principle of Relativity compatible with Magnetic force

    Hello friends, A while back I raised the similar question regarding absolute nature of Magnetic force due to a current carrying wire on a moving charge. But supposedly I was shown to be incorrect. Since, Magnetic filed is a relativistic effect, then every magnetic force should be...
  19. M

    Galilean Invariance and the Special Principle of Relativity

    To what extent is the PoR an extension of the galilean PoI? A stated consequence of the Galilean PoI is that inertial observers cannot determine by experiment if they are "in motion" or "at rest", with a similar consequence being mentioned for the PoR - to what extent to these differ, does...
  20. E

    About the principle of relativity

    When we dealing with questions like "S'-frame moves with respect to S-frame at a velocity u in x direction" then we also assume that "S-frame also moves with respect to S'-frame at a velocity -u in x direction" Why this assumption is correct?
  21. W

    Galilean principle of relativity

    A Galilean transformation consists of a rotation (in space), a boost (in space) and a translation (in space and time). This can be represented for homogeneous coordinates as \left[\begin{matrix}t'\\x'\\y'\\z'\\1\end{matrix}\right]= \left[\begin{matrix} 1&0&0&0&t_{t}\\...
  22. R

    Principle of Relativity, from a mathematical perspective

    I didn't know where to post this question, but the general math forum seemed like the best idea. Newton's Laws are invariant with respect to the Galilean transformations. Maxwell's equations are invariant with respect to the Lorentz transformations. My question is, is it necessary...
  23. V

    Question about Galileo's principle of relativity

    Hello guys, this is my first post. I'm not sure if it is supposed to be in this section. But, if Galileo's principle of relativity says we can't do any experiments which would tell whether we are moving or stationary, why can't we say, for example, that if a vehicle with constant velocity...
  24. N

    Violating the principle of relativity

    It seems really basic, like a remark which probably everyone asks himself when first coming upon electromagnetism, but I can't see the error in my reasoning, which leads to violating the principle of relativity: Imagine two protons passing each other by, each with a speed v, opposite to each...
  25. T

    Violate the principle of relativity?

    Homework Statement In a water pipe, the light moves in the same direction of the water flow. It is determined that the speed of light is dependent on the speed of water flow. Does that violate the principle of relativity? Homework Equations The Attempt at a Solution why the...
  26. P

    Exploring Einstein's Principle of Relativity

    Hey guys. I am a college physics student and ever since this theory was introduced to me in high school, I refuse to believe it. What caught my attention first is that Einstein's Principle of Relativity. Einstein suggest that the laws of physics are the same for all observers in uniform...
  27. L

    How Does Galilean Transformation Apply to Moving Coordinate Systems?

    I am sorry if it is wrong topic , and sorry if it is a bit bad text - translated it from estonian to english. If someone could do it and maybe explain this- that would be great. Homework Statement 1)In the reference system K is point M with coordinates x=5m , y=2m and z=8m. You have to...
  28. E

    The principle of relativity

    Is the general theory of relativity based on the principle of general relativity?or the principle of equivalence, or both of them? And if both of them, which one is more important? Thx
  29. G

    Principle of Relativity and Constancy of Light

    I was reading on a conceptual situation, in which the propagation of light was analyzed from two different reference frames. One was from a stationary reference point, whereas the other was from a reference point that was moving with a velocity v in the direction of the propagation of light...
  30. C

    How Does the Principle of Relativity Ensure Particle L Stays on the 3-Axis?

    1. I'm asked to apply the principle of relativity in Newtonian physics to show that particle L cannot leave the 3-axis and to explain why the identical nature of particles J and K is crucial. 2. An isolated system consists of 3 particles J, K and L J and K have mass m and are...
  31. R

    Question on general principle of relativity

    I want to ask about the two statements. 1) Physics laws remain unchange at any Gauss' coordinates. 2) Physical laws are the same in all reference frames -- inertial or non-inertial. Why is 1st statement better than the second statement in representing the general principle of relativity...
  32. F

    Principle of relativity and energy?

    I was recently having an IM conversation with my friend about the principle of relativity - I'd been reading up on special and general relativity all day. Special relativity is based upon the postulate that all uniform motion is relative, and general relativity extends this to non-uniform...
  33. C

    Time-reverse symmetry of the principle of relativity

    Please look at the attached diagram and let me know if there is a reason for the asymmetric dynamics due to the relative position of rest or, if I have incorrectly interpreted the mechanics. Kev, I haven't forgotten.
  34. C

    The General Principle of Relativity

    The General "Principle" of Relativity In the most general sense, mechanics describe the interactions of space, time, energy and mass. Whether quantum or classical, all mechanics are subject to the principle of relativity with respect to any quantitative values defined for the ontological...
  35. S

    Einstein; The principle of relativity and the law of propagation of light.

    Homework Statement 2.Explain in your own words what Einstein means by “the principle of relativity”, and why it seems to be incompatible with the theory of electromagnetism (or “the law of propagation of light”). Homework Equations Not an equation but Einsteins answer can be seen here in...
  36. R

    About the validity of Einstein’s 1905 Principle of Relativity

    In his first Relativity paper on 1905 Jun 30, Einstein writes the following two versions of what he denotes as the Principle of Relativity (PoR). At the Introduction, PoR-a: {...the same laws of electrodynamics and optics will be valid for all frames of reference for which the equations of...
  37. H

    Principle of Relativity violation

    This has been bugging me for a while and it may seem like a rather stupid question. I've been reading "Relativity" by Einstein and in section 7 of special relativity (the apparent incompatibility of the law of propagation of light with the principle of relativity) Einstein describes a thought...
  38. N

    Length Contraction, Time Dilation and The Principle of Relativity

    Time dilation and length contraction are expressed by the following equations: L=L'*sqrt(1-(v^2/c^2)) T=T'/sqrt(1-(v^2/c^2)) However, according to the principle of relativity, you can't tell which is the fixed frame of reference and which the moving frame, so you can swap L and L' and T...