[ 3 / biz / cgl / ck / diy / fa / ic / jp / lit / sci / vr / vt ] [ index / top / reports ] [ become a patron ] [ status ]
2023-11: Warosu is now out of extended maintenance.

/sci/ - Science & Math

View post   
File: 83 KB, 746x572, Gold.jpg [View same] [iqdb] [saucenao] [google]
4873598 No.4873598 [Reply] [Original]

Hi /sci/ I have a question. When you point a laser to a mirror it reflects in a opposite direction. Why? What happens in a atomic level when the photon hits an atom?

>> No.4873606

Nobody knows, its like magic

>> No.4873610

>>4873606
I bet the Holy Spirit makes the photon reflect

>> No.4873612
File: 2 KB, 32x32, Ghoul.gif [View same] [iqdb] [saucenao] [google]
4873612

Celestia.
Ghoul for /sci/!

>> No.4873614

Also why would a flat surface mater? To us it seems flat, but in an atomic level it is very chaotic

>> No.4873616

There's a really good explanation in QED by Richard Feynman. It's quite a short book, you should read it.

>> No.4873618

>>4873614
why should light care about atomic level variation? the wavelength of light is about 3 orders of magnitude larger than any atomic level disorder.

>> No.4873621

>>4873616
Will look into it.

>> No.4873624
File: 26 KB, 350x390, emma-stone-spiderman-set-12102011-lead.jpg [View same] [iqdb] [saucenao] [google]
4873624

Interaction of light with matter is of course a huge subject. I was thinking about posting a wikipedia link, but I don't even know where I would start. Try thins here for example.

http://en.wikipedia.org/wiki/Refractive_index

(Basically, I think every light question you'd come up with has an explaination in classical electrodynanamics in interaction with surfaces. Of cousre, you can look at the quantum electrodynamics (QED) description of these, which has the classical theory as limit. Quantum mechanical (QM) descriptions are a pain in the ass, however.)

>> No.4873631

>>4873606
Surface plasmons, man. I.e. magic.

>> No.4873640

>>4873624
Okay thanks. Amazing how far a simple question can take you

>> No.4873643

all classical behavior of light can be described without an appeal to photons.

>> No.4873646

>>4873640
I wouldn't have gone deeper than the Fresnel equations,

...but you posted that pic of the bohr model and seemed to want an answer in terms of surface atom interactions. Solid state phyiscs models are a little beyond me, so I don't have a direct answer, and you wouldn't be pleased about statements about some more than complicated green functions anyway.

>> No.4873650
File: 237 KB, 936x1400, cutey_Emma_genau.jpg [View same] [iqdb] [saucenao] [google]
4873650

>>4873643
that's a nice tautology you got there.

>> No.4873658

>>4873650
yes it is, that's the point. Why try to use the quantum behavior to describe an already well described classical one? wave particle duality says they're both valid.

>> No.4873806

Light is particles (photons) but also waves (electromagnetic). Like all other waves, a wave of light will be partly reflected and partly transmitted when it shifts from one media to another. As an analogy you could use a robe and tie a knot on to a wall. If you propagate a wave through the robe by waving it, most of it will be reflected when it hits the wall and come back to you. Light behaves the same way because it propagates as electromagnetic waves.

>> No.4873808

>>4873658
>>4873650
exactly, if you collapse the wave function before passing the light through double slit, they will only illuminate the trajectory in which the slit axis lies, like classical particles that bounce of using Newtonian dynamics.

>> No.4873847

This doesn't really require a big scientific explanation, it's pretty simple. When light hits a rough surface it diffuses and bounces off in all directions and or get absorbed. A reflective surface like a mirror is smooth and absorbs almost no light, so any light that hits it usually bounces off immediately at the same angle.

If you're wondering that's happening at an atomic level, that's just saying that the atoms are more densely packed on that smooth plane, so the photons hit the surface immediately rather than bouncing around inside the material before escaping.

>> No.4873898

>>4873847
Would like a link with proper explination

>> No.4875076

>>4873847
That's not the issue here. You're giving the classical mechanics explanation, considering a brush of light.
OP wants to know what happens in a quantum level, studying individual photons.

>> No.4875245

>>4873643
all behavior of electromagnetism can be described without an appeal to photons. fix'd