The only stupid question is a question not asked

I'm interested in ops question as well..bump

If a bunch of people jump into a pool one by one, they're going to significantly shake up the water. If you get them to all jump in at the same time, you're going to have a decent amount of water ejected from the pool, and then it's no longer shaking. Or if you drop a car into the pool, same thing happens.

There is such a thing as too much energy. With atoms and molecules, the energy that causes jiggling is easier to absorb than the energy that causes significant changes like the ejection of an electron, or the changing of electronic states. What you feel as temperature is caused by the kinetic jiggling of the atoms and molecules you are in contact with. Infrared causes jiggling more so than blue light.

>>7784312
ignore this guy. its flat out wrong.
my sense is its to do with intensity. a toaster/oven uses >300 watts but leds are <10 I think.
might also have something to do with biology but thats not my field. high intensity visible/ultraviolet causes sunburns/cancer but you dont feel it.

>>7784312
This is simplified so much that it is almost bullshit.

The energy of high energy photons is high enough to be absorbed by electrons (UV).
Low energy photons carry only enough energy to thermally excite atoms, so each photon excites your skin thermally. UV photon energy is absorbed by breaking bonds, which does not generate heat but does cause cancer.

>>7784317
Well I doubt OP would understand the resonance frequencies of vibrational modes of organic compounds, because I barely understand that shit. But I think the analogy is good.

>>7784316
You don't know what you're talking about. it has nothing to do with intensity. A 300 W LED still wouldn't be hot. They make lamps like that to grow plants; it stimulates chemical reactions with chlorophyll and shit.

>>7784336
>Well I doubt OP would understand the resonance frequencies of vibrational modes of organic compounds, because I barely understand that shit. But I think the analogy is good.

woah you so smat

op never mentioned equal intensity visible vs infrared light, so relax dude. I think a 300 W visible would feel just as hot if not hotter than a 300 W infrared, but ive never tried. You wouldnt feel a 300 W uv light because its scrambling your fucking dna retard.

now piss off.

>>7784355

>>7784354
im this guy. correction. a 300 w visible light would feel less hot than a 300 w infrared, but its because your body is reflecting a significant fraction, not absorbing.

>>7784354
> I think a 300 W visible would feel just as hot if not hotter than a 300 W infrared

https://www.youtube.com/watch?v=7-Ny2MYje4M

Infrared output and heat generation are synonymous, and a 60 Watt LED is not going to generate heat on the same order as a 60 watt incandescent bulb.

>>7784379
but its because your body is reflecting a significant fraction, not absorbing.

That is literally the same thing as saying the radiation doesn't cause a resonance in the vibration of the molecules your skin is made of.

How would you explain microwave radiation at the same frequency that a microwave oven produces? It will cause a measurable degree of resonance with the water molecules in your flesh, and cook you alive. it will get very hot. It's not because you're less likely to reflect the incoming light.

>>7784385
if youre not reflecting any visible light how can your eyes pick up the light that lets you see people?

the body contains more than just water and it tends to resonate at most infrared frequencies and reflects visible. thats why we evolved to see visible, not infrared.
white people reflect more visible you racist piece of shit.

File: water light absorption spectrum.gif (45KB, 640x452px) Image search: [Google]

45KB, 640x452px

>>7784407
pic related is why we evolved to see visible light, not infrared

But you're beginning to shitpost, so I'm sure this doesn't matter.

>>7784412
Not him, but what does cm^-1 mean in the red line graph? I thought frequency is in hertz?

>>7784418
Wavenumber. There's a wiki page that can explain when it's used. It's just more proper that way.

>>7784412
pic related is exactly what i said, we reflect visible and absorb uv/infrared, good job finding it.

i think weve answered ops question. microwaves are a quirck in the infrared coinciding with a rotational resonant frequency of water molecules. not a lot to do with ops question tho.

>>7784418
speed of light (3e8n/s)=frequecy*wave length

>>7784432
>>7784418
so you can write frequency as spped over wavelength because c is constant = units 1/length, thats basically wave number. guy wants to be vague and seem smart...

>>7784437
>>7784432
That's not the reason. And it ignores the fact that the index of refraction, and thus the speed of light, is a function of frequency for any real medium.

It's more standardized to write it this way, otherwise you might as well include the refractory index of water on that graph as well, and that's information overload.

In QM it's proper to use wavenumber because wavenumber space and position space are related through a Fourier transform.

>>7784451
further information on the refractive index of water:

http://www.philiplaven.com/p20.html

>>7784451
ive always sorta wondered about that. optics seems to contradict relativity (i.e. speed of light is constant in all frames)...

>>7784468
In special relativity the speed of light in a vacuum is constant. In different mediums the speed of the photons will change but that's not the same thing as relativity's "speed of light" .

>>7784495
Not him but, don't they go the same speed, but are absorbed and emitted which causes the measurement to be less than light speed? Or something like that?

>>7784468
>>7784495
Technically the photons in a medium are still moving at the vacuum speed of light, but the observed decrease comes from time gaps between which a photon is absorbed and subsequently generated by interaction with a particle

>>7784495
In Special Relativity, a change of coordinate system will leave the observed velocity of light unchanged. In a vacuum, electromagnetic waves propagate at the speed known as "c."
In other mediums, waves don't necessarily propagate at the same speed, and due to wave interference and such, the group velocity and phase velocity of a wave are also not the same. This is an important distinction that is almost never brought up.

Nothing about this violates SR. It's literally all just wave mechanics in a different medium than a vacuum.

>>7784511
Not entirely true. In the photon picture, you have to also consider a number of paths and their different interference. This is a complicated problem to write down in terms of quantum mechanics.
Watch both explanations in this video:
https://www.youtube.com/watch?v=CiHN0ZWE5bk

>>7784511
huh, thanks anon. its still seems weird though. photons interacting (entering/maybe refracting, and exiting) with, say glass, without losing energy.