
Lorentz Transformations with a Mechanical Time-Globe [video] - espeed
https://www.youtube.com/watch?v=Rh0pYtQG5wI
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dukwon
A Lorentz transformation can be written as a rotation matrix using hyperbolic
trig functions instead of regular ones. This machine works by having grooves
in the shape of hyperbolic lines that the blocks follow.

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antidesitter
Yup. Whereas rotations involve two spatial directions (the plane of rotation),
a Lorentz boost involves a spatial direction and a temporal direction. Also,
the analogue of a rotation angle for a Lorentz boost is a _rapidity_
(hyperbolic angle).

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Ono-Sendai
I did a javascript version here if anyone wants to try the software equivalent
:)

[http://forwardscattering.org/post/36](http://forwardscattering.org/post/36)

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qubex
The device works just by following/‘reading’ the pre-cut Lorentz-encoding
grooves cut into the base of the device. There’s nothing computational going
on in the grid of mechanisms. Replace the base with non-hyperbolic grooves and
you’d get non-relativistic transformations. It just follows the template
encoded for it.

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db48x
No one ever claimed it was a general-purpose computer. Like all special-
purpose computers, it performs a specific computation when used.

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qubex
That’s actually a fascinating point because I both in one sense am not denying
the device’s generality whilst in another sense indeed defending it’s
generality: it might be said that I’m actually saying it’s general because you
can run those grids upon virtually any engraved backplane while at the same
time since reading off the backplane is all the device does I’d be arguing it
isn’t general at all.

This is the mechanical analogue computer equivalent of a digital discrete
computer’s bi-dimensional lookup table.

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stared
This is awesome! (More in the spirit of visualizing Special Relativity:
[https://www.testtubegames.com/velocityraptor.html](https://www.testtubegames.com/velocityraptor.html))

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Davidbrcz
I think I'm in love

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drxzcl
Very accessible!

