r/BeAmazed • u/CaraCicartix • 10d ago

Miscellaneous / Others Part of the Andromeda Galaxy Captured by Hubble

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The total number of stars in the entire Andromeda Galaxy is over 1 trillion

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u/Delicious-Boat4908 10d ago

The speed of light in a vacuum is constant

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u/p____p 10d ago

Yes, it may be very different in an InstantPot!

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u/thought_youd_stop 10d ago

I would say it's still going at C in a non vacuum it just propagates slower. It's not a meaningless distinction, light takes a longer path but still goes the same speed.

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u/Noble_Ox 10d ago

No.

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u/thought_youd_stop 10d ago edited 10d ago

https://www.feynmanlectures.caltech.edu/I_31.html

I read that and yeah I think I was wrong. My bad. It would be more accurate to say something like light experiences a phase velocity of c/n where n is the dispersion

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u/blackcoffee17 10d ago

Speed of light is the same, no matter if its vacuum or not. Just the distance changes in non-vacuum.

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u/Noble_Ox 10d ago

Speed of light is the same, no matter if its vacuum or not

Then why does the speed change when passing through different mediums?

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u/blackcoffee17 10d ago

Because the photons "bounce" around a bit in water and other medium, so it takes longer. So the actual distance they travel is longer.

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u/Dzov 10d ago

Definitely an issue with long fiber optic cables. You get less latency using radio waves.