QB-Relaty

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Een spoedcursus speciale relativiteit, vanuit meetkundig perspectief, met bewegend beeld
Quick course on special relativity, from a geometric approach, with moving display.

I wrote several QBasic programs trying to illustrate features of SRT (Special Relativity Theory). This page shows some examples of some of them.
I wrote also an abstract in English resuming my geometric approach of SRT and describing the functioning and key events of the QB programs within that framework: see "My SRT" page paratwin , under my Relatieve Tijd , particularly for more details on these programs.

See "My SRT" page paratwin for more on this....

Click pictures below to show an animation !

Lightclocks : gauging spacetime

See QB program lichtklok.
Lightclocks as building blocks of relativistic space and matter. Understanding lightclocks is understanding the metrics of SRT spacetime.
A restframe seeing its own lightclock (v=0), a moving lightclock (v<>0), a moving lightclock with the features from the standpoint of the moving system (different simultaneity). Keeping in mind that a simple change of reference transforms the "rest" frame into the "moving" one, and vice versa. Thus understanding the reciprocity with the moving system seeing the rest system's lightclock (many learners don't come to grasp this reciprocity, many paradoxes lay in ignoring it...).
Both spatial (xy) and Minkovsky (xyt) descriptions. The animation of the Minkovsky description is somewhat fallacious as the whole xyt idea is precisely to have time laid out, not running :-) Nevertheless it allows to appreciate the difference of simultaneity notions between rest and moving system.
See "My SRT" under ditto § for more.

Program controls see pictures following :
[SPACE] toggle standpoint rest/moving frame ;
[+,-] velocity v/c ;
[0] toggle view xy/xyt ;
[.] toggle trail dots on/off ;
[ENTER] show Lorentz contraction and dilation (in xyt) on/off ;
[*,/] speed up/slow animation ;
[Lt,Rt keys] rotate y-axis ;
[Up,Dn keys] stretch/shrink y-axis;
[ESC] End.

Lightclock moving, standpoint restframe : an xy space description

The start point moves along x over the turquoise stretch from left to right "with velocity v".
Light rays don't reach their return points simultaneously according to rest frame (as they do in a rest frame's clock).

Lightclock moving, standpoint restframe : an xyt spacetime description

Same case in a spacetime (though 'moving':-) description.

Lightclock moving, standpoint moving frame : an xy space description

Moving lightclock but with the light ray positions according to moving frame: they do reach return points simultaneously.
(Those of a rest system's clock wouldn't, according to the moving frame, reversing the standpoint pictures)

Lightclock moving, standpoint moving frame : an xyt spacetime description

Same case as previous, in a spacetime description.

Relativistic trains : simulation of the watching process, in regression and approach

See QB program relasee9 options 6 and 5.
Actually seeing relativistic objects such as, eg, approaching and receding trains, is a step beyond the mere Lorentz equations involving only measuring results. I called the measured objects, lengths and speeds the Lorentz ones, and those actually seen the Einstein ones....

Twin paradox : home and traveler twin's standpoint, in an xt spacetime description

See QB program relaty8 option 10.
The Twin paradox explained in the Minkovsky framework of Lorentz equations xt.
Both home and traveler twin's conclusions.

Color codes for the journey:
orange = going away,
magenta = instantaneous return
green = coming back

Twin paradox as a watching process : home twin's observation in an xt description

See QB program relasee9 option 9.
How the paradox Twins actually see each other, explained in the Minkovsky framework of Lorentz equations xt.
Case of home twin's observation.

Color codes of observation:
red (shift) = recession
blue (shift) = approach
yellow = light rays.

Twin paradox as a watching process : traveling twin's observation in an xt description

See QB program relasee9 option 9.
How the paradox Twins actually see each other, explained in the Minkovsky framework of Lorentz equations xt.
Case of traveler twin's observation.

Twin paradox simulator : home twin's standpoint

See QB program twinty21 .
The Twin paradox, Lorentz-wise, rendered in a simulator-like setup.
Home twin's conclusions.

Twin paradox simulator : traveler twin's standpoint

See QB program twinty21 .

The Twin paradox, Lorentz-wise, rendered in a simulator-like setup.
Traveler twin's conclusions.

Twin paradox, a watching process simulator : home twin's observation

See QB program twinseen .
The paradox Twins actually watching each other, rendered in a simulator-like setup.
Home twin's observation.

Twin paradox, a watching process simulator : traveling twin's observation

See QB program twinseen .
The paradox Twins actually watching each other, rendered in a simulator-like setup.
Traveler twin's observation.