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originally posted by: greenreflections
thank you.

I take it you replied affirmative to my first question.
would the same apply to photon also?

thanks for avatar tip.

You're welcome for the tip.

I purposely avoided a direct answer to your question about whether the electron will get where you aimed it because you said there's nothing in its way. That's not the only consideration. A few hundred parsecs is still in the Milky way, which has a very weak magnetic field about 1/50,000 that of Earth's, plus or minus depending on where in the galaxy you measure it. When you send a charged particle such as an electron through a magnetic field, it doesn't go in a straight line. But if you know the magnetic field strength and other factors you can predict how much the electron will curve. In such a weak magnetic field it's not a lot but a few hundred parsecs is a long way and unless your target is ginormous you'd probably miss the target, unless you took this curvature into account when you aimed.

Photons are also thought to be stable and unlike electrons they won't curve in the magnetic field, though they can be affected by gravitational fields (as can the electron). If you really want to get esoteric and geeky you can read stuff like the following, but this probably wouldn't be taught to first year university physics students who would just be taught that the photon has no mass and is stable:

How stable is the photon?

More advanced students are taught that in fact we can't really prove the photon mass is exactly zero but can only establish limits, so in that case you could say if it's not zero mass, it's pretty close to zero, but if it has even a tiny amount of mass, that changes the picture and it might not be completely stable but it would still have a lifetime of at least three years. I suspect photons probably have no mass but to prove it's exactly zero is difficult. I also try to keep in mind that at one time neutrinos were thought to be massless and now we think they have a tiny mass, however even now we don't have accurate measurements of neutrino mass partly because it's so tiny.

originally posted by: BASSPLYR
a reply to: Bedlam

crazy as in there's nothing to it or crazy like it's too bizarre and will derail thread entirely.

I find it really interesting, what's funnier is you just came up with it out of nowhere. But I've avoided it on the thread, it's up to you, I think a few folks will have a meltdown. C'est la vie.

a reply to: Bedlam

so keep reading up on it. cool. all questions beating around the Bush about it like I have will now cease.

so um. colors of objects like plants n stuff. if a tree is green does that mean green is the only wavelength of light the plant rejects hence we see green.

also is the color black every wavelength being rejected or absorbed

originally posted by: BASSPLYR
a reply to: Bedlam

so keep reading up on it. cool. all questions beating around the Bush about it like I have will now cease.

so um. colors of objects like plants n stuff. if a tree is green does that mean green is the only wavelength of light the plant rejects hence we see green.

also is the color black every wavelength being rejected or absorbed

Well sort of yes certain wavelengths are absorbed your not necessarily seeing a single frequency of light. Consider for instance that you are looking at a tree and it appears green to your eye. There are several frequencies of light striking your eye with varying degrees of intensity. Yet your eye-brain system interprets the frequencies that strike your eye and the shirt is decoded by your brain as being purple. So color is just out interpretation of light frequencies. Without our interpretation they have no color.
Black is not a color a black object absorbs all the colors of the visible spectrum and reflects none of them to the eyes. So our brain interprets no light ad black but since its not really a color but an interpretation of our brian. Does black even exist??

a reply to: Bedlam

Ah go on. A quick Google makes for interesting reading.

So the charge on a charged particle is effectively infinite, but is tempered with distance due to EM field virtual particle polarisation?

A-and somehow reducing that EM field might have crazy effects?

a reply to: dragonridr

good point. does black even exist. I guess black is an absence of everything.

you know what used to be a mind trip when I was a little kid. mixing colors of paint. or crayons. I always knew to get black you'd mix all the colors together.

but since that color is the wavelength it rejects and doesn't absorb. shouldn't all the colors mixed together reject every wavelength and appear like a rainbow like the surface of an oil slick.

obviously that's not what happens. I guess it turns black because you've mixed every color together and so everything is being absorbed.

so the next question is how do you get gloss black. if all the wavelengths are being absorbed. like why is catwoman in her latex catsuit shiny? shouldn't she be like ninja black. and sneeking up on criminals, if thats even possible wearing stilletos. not that I'm complaining. me likes me some catwoman. (can you tell?)

but any ways. should it matter that there is matte and gloss black if it's black because it absorbs all light spectrum.

and if light obviously is being bounced off then why is it the color black. again shouldn't it be some weird pearlescent color like on the surface of an oil slick.

so what gives. somebody do some 'splaining please

plant question regarding light wavelengths.


first part of question. if one were to take a reading at noon standing in say a grassy field (or your sidewalk. point is on the ground or sea level) what color would dominate?

since blue is scattering in the atmosphere what's reaching the surface most? would it be dominant in the yellowish green spectrum?

hope what I'm asking makes sense.

next part of the question is, if the wavelength is predominantly yellow green. then why are plants rejecting their most abundant food source?

is nature stupid like that sometimes? or are they making the most out of the chemistry they got to work with for energy production?

or is this post pointing to me being the example of stupid nature?

why are metal halide such as high pressure sodium or magnesium bulbs more efficient at converting energy into light/lumens than say a filament bulb or a flourescent tube. whats so potent about hps, mh bulbs efficiency wise?

finally what's the deal with LED lights. they are bright as hell. obviously they give you better bang for buck over hps or mh in terms of wattage to lumens. but if you made a led the same size of a hps bulb. not a bank of led. just one scaled up to the size of say a coke can. would it have higher lumen out put than a hps.

finally how do LEDs work. I guess that's a goid question too. maybe we should start with that since i have no idea.

so recap, after my flight of thought.

why hps, mh type bulbs so much more efficient at converting electricity to lumens over just about everything but a led.

how's an led work?

ok last question in my Yoohoo look over here attempt to bring thread away from certain lines of questioning.


this ones fun I promise.


everybody out there. whats your favorite invention or device in science fiction. like say doc Brown's delorian, or the time machine from the movie Primer. the neurolizer from men in black etc.... what made you say, damn I wish i had one of those.

for me I'd have to say George jetsons suitcase/flying car. or an ironman suit. its a toss up.




finally as a side note. can anybody out there give me a definitive answer as to how many multiple timelines there are for that movie Primer. I had to watch that movie a second time with a notepad drawing multiple timelines connecting and crisscrossing. by the time I was done my doodle of looked like a cats cradle. I think I came up with 8 time lines. for those who haven't seen the movie it's a great mental exercise to keep tract and pay attention to all the timelines and their subtle differences. just make sure you havevsone Excedrin handy. you'll need it.

originally posted by: BASSPLYR
but any ways. should it matter that there is matte and gloss black if it's black because it absorbs all light spectrum.

so what gives. somebody do some 'splaining please

Why does glass partially reflect light when it has no color at all? Newton had an explanation but he knew it wasn't quite right and it took centuries to find a better answer as Richard Feynman explained in his Auckland lecture:

QED: Fits of Reflection and Transmission -- Quantum Behaviour -- Richard Feynman (2/4)

originally posted by: BASSPLYR
since blue is scattering in the atmosphere what's reaching the surface most? would it be dominant in the yellowish green spectrum?

I'm not sure how accurate this picture is but it's probably not too far off and it's worth a thousand words if you can read what it's telling you.

EM radiation through atmosphere versus wavelength


Most visible light isn't attenuated too much but ultraviolet is as shown. The amount of blue light scattered is a very small percentage of the total blue light so plenty of blue light still hits the ground, just look at something blue outside to confirm this.

next part of the question is, if the wavelength is predominantly yellow green. then why are plants rejecting their most abundant food source?

It's not and they don't. Yellow green isn't a "food source" for plants, blue and red are:

hyperphysics.phy-astr.gsu.edu...

only the red and blue ends of the visible part of the electromagnetic spectrum are used by plants in photosynthesis. The reflection and transmission of the middle of the spectrum gives the leaves their green visual color.

is nature stupid like that sometimes? or are they making the most out of the chemistry they got to work with for energy production?

In some respects evolution is very stupid and in other respects it's very "smart", it's a complicated topic which is not adequately described with over-simplified characterizations.

a reply to: Arbitrageur

going to listen to that lecture with some earphones at work today and pester you guys with questions later this afternoon.

so that picture is pretty Interesting. would it make sense for plants to have deep blue leaves if they wanted to be the most efficient at collecting solar energy for fuel if they had the chemical means to do so? wonder how efficient they are or if they even can absorb that tremendous amount of near infrared and mid infrared that reaches the surface.

originally posted by: BASSPLYR
would it make sense for plants to have deep blue leaves if they wanted to be the most efficient at collecting solar energy for fuel if they had the chemical means to do so?

They do use blue light (and red) so they would have less blue light available for energy if they reflected it, but you already knew that from the wording of your previous question about reflecting green, so your questions aren't consistent.

originally posted by: BASSPLYR
how's an led work?

The photons are screams from electrons falling into a hole.

originally posted by: BASSPLYR
so the next question is how do you get gloss black. if all the wavelengths are being absorbed. like why is catwoman in her latex catsuit shiny? shouldn't she be like ninja black

If it's glossy, you see ordered specular reflections (mirror like) from the transition between two different...well if it was RF I'd say impedances, but it's related to the speed of light in that medium, for optics guys I guess it's index of refraction but it's all the same mathematical entity, just smushed a little different for those guys.

Whenever EM hits an impedance change (back to my world) there's a Maxwellian set of crap that happens. You get reflection, refraction, absorption, boundary waves (don't ask) and Bob's your uncle, right at the surface, before the black part gets its hands on it, so to speak.

That's where your shiny black comes from, because you're getting specular reflections from the boundary. If it's matte, you still get the same amount but it's diffuse, so not shiny.

Then the part that enters the coating is absorbed (mostly) by the dye/pigment and converted to heat. So what you see color wise is black.

More advanced ultrablack stuff tends to either have a better match in terms of impedance, or gets more than one shot at the photon.

BTW, this is the same reason you can see water as fog. Water's clear. But it doesn't have the same impedance as air, thus you get a whole set of other stuff. It's also where you get expressions like "diamond of the first water", where you apparently grade diamonds as how well they match the impedance of water. If you had, for example, a material that had exactly the same impedance of water, and was totally clear, if you dropped it into the water, it would vanish.

This is why you have, on stealthy objects, both RAM (that's the black coating on the patent leather suit) and cleverly angled surfaces (thank you Dr Ufimtsev). If the RAM and the clever yet generally classified internal structure of the airframe absorb all the incident radar wave, why bother shaping it? Because the RAM doesn't have the same impedance as air, so you get specular reflection from the transition. The shaping is to make it "matte". And it's why you have a residual RCS, and it's also why plasma works to improve that.

It's also why, when someone's talking about stuff like radio waves and people, you always see me reply that you, not being air, will cause impedance transitions at every change, and lose RF energy to the reflections and boundary waves. It's the same thing. You, not being air, are "shiny" to RF. And your bones are shiny, and your dura mater is shiny, and the CSF is shiny, and the pia mater is shiny, and the brain is shiny. Every interface causes loss to reflection. So you have merry hell getting an ordered beam aimed at a specific place, unless you're using x-rays or higher, because they have so much energy they don't deflect much. But they still do.

Now, if you were a pair of visionary physicists and an engineer in the late 30s, early 40s, you might ask yourselves, "Self, how do I change the characteristics of space around a metal object such that the object appears to have a different, better matched impedance, and thus no specular reflection at all to radar, like fine diamonds in distilled water?" and asking, discover something new.

a reply to: Arbitrageur

Well on the picture you posted of wavelengths. It looked (and I could be wrong-usually am) that blue and purple were the least abundant of the visible spectrum. SO I was thinking if plants had a choice instead of being green and loosing the green wavelengths for fuel which I thought looking at the picture were more abundant. It would be better for plants to trade for rejecting blue and purple wavelengths and get the benefit of the slightly more abundant green. I dunno I was looking at the picture from my phone trying to blow it up while squinting at the screen on a bus ride to work.