HomePhysicsRelativity on Rotated Graph Paper (a graphical motivation)

# Relativity on Rotated Graph Paper (a graphical motivation)

(primarily based on https://www.physicsforums.com/threads/teaching-sr-without-simultaneity.1011051/post-6588952 and https://physics.stackexchange.com/a/689291/148184 )

Within the penultimate draft, I had a non-algebraic motivating argument (which additionally motivates time dilation and size contraction)
that needed to be not noted as a result of the article was already too lengthy.

This argument now seems in Introducing relativity on rotated graph paper (Ch 7), my contribution to a lately revealed ebook: Educating Einsteinian Physics in Colleges
Kersting and Blair, Routledge 2021, https://doi.org/10.4324/9781003161721
(has supplementary materials on the backside: https://www.routledge.com/Educating-Einsteinian-Physics-in-Colleges-An-Important-Information-for-Lecturers/Kersting-Blair/p/ebook/9781003161721 )

## The storyline… ranging from Einstein’s rules

The storyline goes like this:

• The Velocity of Gentle Precept and Bob’s Velocity offers the form of shifting observer Bob’s light-clock diamond (with edges parallel to the sunshine cone, to the rotated graph paper).
• building:
Draw Bob’s worldline.
Bob’s diamonds can have a diagonal alongside Bob’s worldline and edges parallel to the rotated grid.
The scale of the diamonds corresponds to the spacing of the mirror worldlines, equidistant from and parallel to Bob’s worldline.
However what determines the scale of the clock diamonds? (What occasion F on Bob’s worldline marks the signal-reflections?)
• The Relativity Precept determines the dimension (the scaling) of Bob’s light-clock diamond.
(That is what I name the “Calibration Drawback”.)
• SIGNAL-EXCHANGE EXPERIMENT: Two inertial observers meet at an occasion O.
2 seconds after they meet, they ship a sign to the opposite.
We anticipate they’ve the identical outcomes, in accord with the relativity precept.
(I may have chosen “1 sec”… however the diagram is extra cluttered.)

## An instance: the  ##v=(3/5)c## case

• Take ##v=(3/5)c## for simplicity.
The makes an attempt:

[* possible analysis: Since the round-trips are equal in both of the previous cases, we might
expect the geometric mean ##sqrt{(3.2)(5)}=4## to be the expected result of their signal-exchange experiment.]

Do this for ##v=(4/5)c##.

Play with these utilizing
https://www.geogebra.org/m/HYD7hB9v#materials/UBXdQaz4 (make certain BOB’s diamonds are proven)
https://www.geogebra.org/m/kvfsq664 (up to date)… (make certain BOB’s diamonds are proven)
[You can manually adjust Bob’s velocity and “lengths [in the lab frame]” of the sunshine clocks.]

To acquire the textbook method relating the time-dilation elements and relative velocity, we’d to proceed alongside the traces of my AJP article.

However the level is that we will present (with a geometric building and with out algebra) how the Relativity Precept and the Velocity of Gentle Precept suggest the incompatibilities with Absolute Time and Absolute Area, and counsel the necessity for the time-dilation and length-contraction results (as side-effects), on the way in which to establishing the equality of light-clock diamond areas (which is actually the invariance of the sq. interval).

Relativity on Rotated Graph Paper
Study About Relativity on Rotated Graph Paper
Study About Spacetime Diagrams of Gentle Clocks

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