# Thread: rigid vs. nonrigid transformations

1. ## rigid vs. nonrigid transformations

There are at least three special kinds of rigid transformations. These are, not in any order of importance, translation (T), rotation (R), and reflection (M). Using Cartesian coordinate geometry of 2D Euclidean spacetime, the following mappings always hold true.

$T(x,t)=(x+\\Delta x, t+ \\Delta t)$

$R(x,t)=(xcos\theta-tsin\theta, xsin\theta+tcos\theta)$

$M_S(x,t)=(x, -t)$ reflection in the space axis.

$M_T(x,t)=(-x, t)$ reflection in the time axis.

The distinction of all rigid transformations is that they do not stretch (dilate), shrink (contract), or twist (curve) the transformed events. Two transformed events do not move closer together or farther apart in spacetime. In other words, events always stay the same distance from each other. Furthermore, the Pythagorean Theorem determines this distance. The mechanics is Newtonian and the spacetime is Galilean.

Nonrigid transformations give relativistic mechanics and Minkowskian spacetime. For transformed events involving dilation and contraction refer to Einstein’s special theory of relativity and for the ones involving twisting and curvatures refer to Einstein’s general theory of relativity.

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Is there any other "non-main" rigid/non-rigid kind of transformation?

What about division (breaking)?

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Originally Posted by GUILLE
What about division (breaking)?
The divisions of vectors are undefined as far as I know. I'm not sure about tensors divisions.

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Originally Posted by AntonioLao
The divisions of vectors are undefined as far as I know. I'm not sure about tensors divisions.
A division of something mathematical as a vector I think that can only lead to other vectors (depending on the number of parts resulting).

If not, is it possible that, let's say, if a tensor is devided, then the parts are vectors?

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GUILLE,

Vectors have two components, the magnitude and the direction. Although magnitude can be divided, direction cannot.

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Originally Posted by AntonioLao
GUILLE,

Vectors have two components, the magnitude and the direction. Although magnitude can be divided, direction cannot.
Can the parts of the magnitude re-unify?

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Originally Posted by GUILLE
Can the parts of the magnitude re-unify?
parts re-unified signify continuity and divided signify quantization.

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## Re: rigid vs. nonrigid transformations

Originally Posted by AntonioLao
parts re-unified signify continuity and divided signify quantization.
Quite right, what about the process of division, I have been thinking about this fine point for awhile, the process it seems is continuous and the result is defined, but if we can agree to a mathematical process of division, then I think we could define this universally for all particles. It is necesarily discrete and immaterial what process we agree on so long as it is scaleable.

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## Re: rigid vs. nonrigid transformations

Originally Posted by theunify
but if we can agree to a mathematical process of division
Logarithmically, a process of division becomes a process of subtraction where the dividend is replaced by the minuend and the divisor is replaced by the subtrahend.