Imagine that the original pulse of light was just 2 waves. As the pulse moves into the new medium it will slow down, but you will not get a pulse of 1 wave or 3 waves. The number of waves has to be conserved. It must stay 2 waves. So what must change for those two waves is their length. The number of waves (per second) or frequency stays the same.

​​​@@jeffreyhuvar1379Unless the speed of light actually changes, which is the concession no one wants to make. They're making an *assumption that the speed of light remains the same. You can still have two waves, traveling at a changed speed, which changes the frequency while the wavelength remains the same. No new wave needs to be created.

​@@jeffreyhuvar1379this is very much competely not true

Depends if he is left or right handed. You could film yourself writing on glass and then mirror the image to get the same effect

(Not the Prof) What I see it as is how cold is just the absence of warmth. As darkness is the absence of light.

Love it when my Fandersons™ talk to each other. That is definitely how we learn best. And yes, I agree, darkness is the absence of light. Cheers, Dr. A

Thanks professor

@@yoprofmatt If darkness is "just" the absence of light, then light must necessarily be the absence of darkness. So to create light we must take away something that preexisted it? So nothing must necessarily be something? Okay, okay I know this isn't a philosophical channel, but it's fun. I've come to the understanding that "nothing" is another (in a long list) of meaningless misnomers. To call it a misnomer is giving the concept too much credit. It doesn't exist at all. @MuhammadAli-lg5kz, there is no darkness - only ignorance. You can interpret that any way you want and you'd always be right. From a physical perspective there's the CMB light that envelopes our entire universe, though our God-given eyes (in His wisdom and mercy) have made them not perceive it. Beyond our universe, is another. We're in a Russian doll of universes. Outside all the universes is God. There is nothing God can't know. If He didn't know it, it wouldn't be. As He *is* The "Be" that all other beings depend on. He IS. Everything else is-something. But He just IS. So it stands to reason that as "long" and as "far" as God perceives (which is infinitely) then there can be no nothing. His very perception dispels nothingness/darkness. His perception is infinite. So there can be no darkness. The physical darkness you perceive is only an illusion. The whole universe is lit up. The only darkness is our own lack of omniscience. Our own ignorance. Hope this helps.

Vexing initially. Got this on a grad school exam. Cheers, Dr. A

@@yoprofmatt Kewl......It's a tricky one, for sure!