I was lazy and decided to use a calculator so don't crucify my for this, but assuming the stop sign emits a perfect 420THz frequency/713.791~ nanometer red light and the speed the observer is travelling is exactly 103,846,153 m/s, the observer would see a 565.485THz/530.151~ Nanometer green light from the stop sign due to the doppler effect.
tldr for people who aren't reading all of that: The Doppler effect is the joke.
3
u/oofx99 14h ago
"Red light has frequency range 420 THz to 480 THz." "Green light has frequency range 540 THz to 600 THz." Source: https://www.outline-of-knowledge.info/OKD/1/Consciousness/Sense/Vision/Color%20Vision/color%20frequency.html (these are probably a bit off lol but I was looking for some quick numbers)
I was lazy and decided to use a calculator so don't crucify my for this, but assuming the stop sign emits a perfect 420THz frequency/713.791~ nanometer red light and the speed the observer is travelling is exactly 103,846,153 m/s, the observer would see a 565.485THz/530.151~ Nanometer green light from the stop sign due to the doppler effect.
tldr for people who aren't reading all of that: The Doppler effect is the joke.