1. SPECIAL RELATIVITY PARADOXES Faster than light? Twin paradox
(NOT)
Faster than light?
Twin paradox
Causality paradox

2. Violation of ultimate speed (not)
¾ c
¾ c
You
What is speed of Laura relative to George?
¾ c is Laura’s speed in Your IRF, but relative to George
Your clock runs slower (time dilation)
Your distances are longer (length contraction)
George concludes Laura’s speed (distance/time) relative to
You is less than You measure – less than ¼ c actually
George agrees his speed is ¾ c relative to you
Total less than c
Note: Disagreements only for 3rd party speeds

3. Twin Paradox (not) Observers in uniform relative motion both say the others clock runs slow
Ages less than X years
FACT
Ages X years
Stay-at-Home twin IRF : Travelling twin time dilates, ages slower
Travelling twin IRF : Distance travelled is contracted, takes less time

4. A long, long way away Violation of Causality (not)
Two observers in relative motion disagree
about the temporal order of events…
A long, long way away
Two observers passing in the street
disagree about whether the alien fleet
has yet set out to invade Earth
Note: causality is
not violated
There was a young lady named Bright,
Whose speed was far faster than light
She set out one day
In a relative way,
And returned home the previous night.
- Arthur Henry Reginald Buller
YES NO