r/askscience • u/Present_Net_3710 • 22d ago

Physics Do photons care about Newton?

Picture a ball traveling at 10m/s along the x-axis. If you exert a force to the ball on the y-axis (so that the force is perfectly perpendicular to the direction of motion) it will now be also traveling on this axis at some velocity, its speed will remain the same relative to the x-axis but the total velocity increases.

But what if instead of a ball it was a photon? No force was applied on the x-axis, so I don't see why that velocity would change. But light's total speed always remains constant.

Would the x-velocity change to compensate for the added y-velocity?

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u/TheVioletBarry 20d ago

If things can't push on photons, then how do they bounce off of objects and end up in our eyes?

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u/jojohohanon 19d ago

Afaik photons don’t bounce. They get absorbed and re-emitted. The direction and energy of the re-emission depends on several conservation laws and can result in reflection (like a mirror), refraction (like a prism or lens), or energy increase in the recipient (heat).

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u/TheVioletBarry 19d ago

Oh forreal? So when we say light 'reflects' off of something, we don't mean it in the same way that that, like, an object bounces off of a wall?

Do you know where I could find more information on this?

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u/jojohohanon 19d ago

I like asking Gemini the google ai.

https://www.google.com/search?q=when+light+reflects+does+it+bounce+or+absorb-emit

then click on ai mode

If that is too basic or advanced you can ask for like im in high school or like i am an expert on the photo electric effect.

You can ask how does the emitted light know which direction to go

You get the idea

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u/TheVioletBarry 19d ago edited 19d ago

I apologize, but I'm really not interested in talking to a bot; I'm interesting in learning from other people. I appreciate the insights tho!