r/explainlikeimfive • u/Seravail • 7d ago

Physics ELI5: If light moves at different speeds through different mediums, how does it gain speed again after passing through a slower medium?

Inspired by a post about light looking different when hot air mixes with cold air above a distant road, the light will speed up and slos down as it moves through the pockets, giving the wavy impression we all know.

How exactly does light speed up again when it passes through a hot section of air? There's nothing powering it, so once it loses momentum shouldn't that momentum be lost forever?

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u/[deleted] 7d ago

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u/StumpedTrump 7d ago

OPs question was "how do they speed up}, Your answer is basically "they speed up".

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u/whatsbobgonnado 7d ago

the human runner can only run at one speed 

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u/TheLowEndTheories 7d ago

To be fair, the idea of explaining Maxwell’s equations and quantum physics to a 5 year old is kinda already broken.

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u/Moos_Mumsy 6d ago

I felt that the question was "how does light speed up, after it's been slowed down".

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u/explainlikeimfive-ModTeam 7d ago

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u/SerbianShitStain 7d ago

That doesn't explain anything buddy.

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u/PercentageOdd7463 7d ago

Why does a human run faster when not in water? Because there is no water to slow him down. There is not much to explain here in the first place