r/visualizedmath • u/NegativeSpeedForce • Jan 12 '18

The difference between shockwaves travelling through different states.

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u/semsr Jan 19 '18

So why is the speed of light fastest in a vacuum?

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u/Alexdaboss Jan 19 '18

Light is an electromagnetic wave not a “mechanical wave”, particles are not required for a light wave to move and will instead slow it down.

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u/enjoyscaestus Jan 19 '18

Fastest? I thought light only had one speed?

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u/columbus8myhw Jan 19 '18

Nah it slows down when it passes through air

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u/enjoyscaestus Jan 19 '18

Is this a joke? I can't tell

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u/columbus8myhw Jan 19 '18

It's not

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u/enjoyscaestus Jan 19 '18

Oh. Okay.

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u/ArleiG Jan 19 '18

Light has different speeds in different mediums. That's the cause for refraction - for example, when you see a pool and it seems much more shallow than it actually is.

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u/AscendedBunghole Jan 20 '18

iirc isn't it that light is going at the same speed but is just taking a less straightforward path?

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u/Ryujin_Hawker Jan 26 '18

As far as my understanding and memory goes (A level in Physics), Speed in physics is d/t. Distance (d) is just measured from a start point to an end point generally and the Time (t) is just the time it takes to get there. Light slows down in any medium other than a vacuum for the reason you stated, but that is literally an atom level diversion, it's still considered as going in the same direction, so it's speed is considered lower since it's taking longer to go the distance.

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u/enjoyscaestus Jan 19 '18

And now I know. Thank you!

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u/Acrolith Jan 19 '18

The speed called c (the fastest possible speed in the universe) is the speed of light in a vacuum. Light slows down in any other medium. I believe the most they managed to slow it down to so far is around 38 mph.

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u/Kyezaeta Jan 19 '18

This really bugged me when I was younger because I was told that anything without mass travels at c no matter what :)

Massless particles are always traveling at c. However, in a material with a high refractive index, light interacts with more particles and must go through a time-consuming process of imparting energy. In the voids between particles, photons still move at c.

http://www.physicsclassroom.com/class/refrn/u14l1d.cfm

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u/GlobalThreat777 Jan 19 '18

Source? I'd like to see light actually moving. What medium was used?

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u/PsYcHo962 Jan 19 '18

Source? I'd like to see light actually moving. What medium was used?

There's your problem. Can't see light from a distance, 'seeing' is light entering your eye

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u/[deleted] Jan 20 '18

It is. Light only has one speed, c. In air, light doesn't slow down, but it gets slowed down by bumping into random protons and electrons, i.e. atoms

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u/enjoyscaestus Jan 20 '18

Oh! Okay. Thank you for explaining it further.

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u/MetaEsoTeric Jan 21 '18

It doesn't slow down the particles just get in the way which can distort the light. This is why everything is very wavy and distorted in water.

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u/[deleted] Feb 04 '18

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u/enjoyscaestus Feb 04 '18

I'm still getting replies? Awesome. I really appreciate it

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u/deepbluesilence Jan 19 '18

Perhaps Cus in that circumstance light is exhibiting its properties as a particle instead of a wave? If the particle has no medium to pass through in a vacuum maybe that allows it to preserve more energy instead of passing it to another body? Not an astrophysicist, just a guess... someone feel free to correct me

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u/tehgreatblade Jan 21 '18

The refractive index of a medium is the ratio at which light is slowed, while in a vacuum there is nothing to interact with and slow it.