MinutePhysics Special Relativity Series

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kith said:
Does anybody know of a computer simulation which does something similar to minutephysics' time globe?
Have a look at my GeoGebra visualization https://www.geogebra.org/m/bFxv6tja
that I used in my Insight https://www.physicsforums.com/insights/relativity-variables-velocity-doppler-bondi-k-rapidity/
(which underlies the methods described in my other Insight https://www.physicsforums.com/insights/relativity-rotated-graph-paper/ ,
which could be described as a pencil-and-paper version of the "spacetime globe" )
 
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Speaking of which:

 
As soon as I saw the subtitle of the video I knew he'd make the error he makes at 6:11, when he talks about observers traveling toward each other at the speed of light. The "1 + 1 = 1" business is just wrong. It's really "##1 \pm \, v = 1##," with ##0 \leq v<1##:

##\dfrac{1 + v}{1 + (1)(v)} = 1##

and

##\dfrac{1 - v}{1 - (1)(v)} = 1##,

where the latter equation explicitly rules out ##v = 1##.
 
ZapperZ said:
Don Lincoln is coincidentally delving into many aspects of SR at almost the same time. So here is another video by him. This time, he's tackling the concept of "length contraction".
Don said: "If you start with a basketball, and accelerate it at high speed, it'll look like a pancake."

It will be shaped like a pancake but unless you're very close to it, the basketball will look spherical, and rotated way from you.
 
David Lewis said:
Don said: "If you start with a basketball, and accelerate it at high speed, it'll look like a pancake."

It will be shaped like a pancake but unless you're very close to it, the basketball will look spherical, and rotated way from you.
Everyone watching/reading this thread has to be aware that in this context the word "look" has to be taken literally - it's what you'll actually see based on light traveling to your eye along paths of different lengths from different points on the object.