Lorentz- and Galileian-transformation

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In summary, the Lorentz transformation is merely the idea, prior to SR that velocities are added linerally. The Galileian transform is the transformation that is used in relativity, and it tells you how the coordinates of an event (t,x,y,z) transform when you go from one inertial frame to another.
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Eivind
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What`s the difference between Lorentz- and Galileian-transformation?
 
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The Galileian transform is merely the idea, prior to SR that velocities are added linerally. In other words for the train at v, a beam of light sent across the train, proceeds at c+v from the caboose and at c-v if sent from the engine.
 
  • #3
one possible difference is that in galileo relativity light propagates with infinite velocity whereas in Einstein's relativity it propagates with finite invariant velocity.
 
  • #4
The Galilean transformation tells you how the coordinates of an event (t,x,y,z) transform when you go from one inertial frame to another in the non-relativistic case. Or rather, in the considered space-time before relativity.

Taking into account the fact that the speed of light is the same in all inertial frames the transformation laws are changed and these are called the Lorentz transformations.

Prior to relativity the Galilean transformation was certainly well known, but barely used. Nobody bothered to give it a name. It's actually pretty a trivial transformation and doesn't deserve such a fine name.
 
  • #5
bernhard.rothenstein said:
one possible difference is that in galileo relativity light propagates with infinite velocity whereas in Einstein's relativity it propagates with finite invariant velocity.

I think this should read "in galilean relativity the fastest signal propagates with infinite velocity whereas in Einstein's relativity it propagates with finite invariant velocity". If I recall correctly, the speed of light was known to be finite around the time of Galileo or soon thereafter.
 
  • #6
if i recall correctly Galileo measured the two way speed of light measuring the involved time interval using the beats of his heart obtaining for it a zero value and as a consequence light was cconmsidered to propagate with infinite speed. i do not think that the precision of time intervals measurement took place soon after Galileo.
 
  • #7
http://en.wikipedia.org/wiki/Speed_of_light agrees with your characterization of Galileo's experiment. However, Romer (1676) [compare with Galileo (1564-1642)] was apparently the first to observe the finiteness of the speed of light.

In any case, I think it's safe to say that the speed of light (whether finite or infinite) played any key role in the first formulations of Galilean relativity or the Galilean transformations. Only in historical retrospect is there a relationship... in the sense that the speed of light is the maximum signal speed, and that the Galilean transformations are a limiting case of the Lorentz Transformations via this maximum signal speed.
 
  • #8
galileo and lorentz

Eivind said:
What`s the difference between Lorentz- and Galileian-transformation?
In a recent paper
Ralph Bayerlein, Two myths about special relativity," Am.J.Phys. 74(2) 2006 looks for an answer to the question "Does the Lorentz transformation reduce to the Galilean transformation when the ratio v/c is small"? The answer is no as the author shoes.
 
  • #9
bernhard.rothenstein said:
In a recent paper
Ralph Bayerlein, Two myths about special relativity," Am.J.Phys. 74(2) 2006 looks for an answer to the question "Does the Lorentz transformation reduce to the Galilean transformation when the ratio v/c is small"? The answer is no as the author shoes.

...meaning that no matter how small v is (with a finite c), relativistic effects can be detected, e.g., with a precise enough clock.

But when v/c is zero, a condition that Baierlein explicitly avoids, (realizable, e.g., by allowing c->infinity while keeping v fixed), the Galilean transformation is a limit of the Lorentz transformation.
 
  • #10
Thank you for all the answers!
 

1. What is the difference between Lorentz and Galileian transformations?

Lorentz transformations are a set of equations that describe how measurements of time and space change between two reference frames that are in relative motion. They take into account the principles of special relativity, such as the constancy of the speed of light. Galileian transformations, on the other hand, are a simpler set of equations that describe how measurements of time and space change between two non-accelerating reference frames. They are based on the principles of classical mechanics and do not take into account the effects of special relativity.

2. Why do we need both Lorentz and Galileian transformations?

We need both Lorentz and Galileian transformations because they are applicable in different situations. Galileian transformations are useful for describing the motion of objects at relatively low speeds, while Lorentz transformations are necessary for accurately describing the motion of objects at high speeds, close to the speed of light. Using the appropriate transformation for a given scenario ensures that our measurements of time and space are accurate.

3. Can Lorentz and Galileian transformations be used interchangeably?

No, Lorentz and Galileian transformations cannot be used interchangeably. Galileian transformations are only valid for low speeds and do not take into account the effects of special relativity. If we try to use Galileian transformations at high speeds, we will get incorrect results. Lorentz transformations are more general and can be used for all speeds, but they reduce to Galileian transformations at low speeds.

4. How do Lorentz and Galileian transformations affect the measurement of time and space?

Lorentz and Galileian transformations affect the measurement of time and space by accounting for the differences in how these quantities are perceived by observers in different reference frames. They take into account the fact that time and space are relative and can appear to be different depending on the observer's frame of reference. These transformations ensure that the laws of physics are consistent for all observers, regardless of their relative motion.

5. What is the significance of Lorentz and Galileian transformations in modern physics?

Lorentz and Galileian transformations are fundamental concepts in modern physics, particularly in the fields of special relativity and classical mechanics. They provide a mathematical framework for understanding how measurements of time and space change between different reference frames, and they have been extensively tested and confirmed through experiments. Without these transformations, our understanding of the fundamental laws of physics would be incomplete.

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