Is there any relation between wavelength and brightness?

In summary: I used the "middle gray" of the smoke and compared it to the other colors of the rainbow to determine how many bits the digitizer was using for color resolution. In summary, The brightness of a color is determined by the sensitivity of the optical equipment used to measure it, as well as the colors and context surrounding it. Brightness is subjective and can vary depending on individual perception. Intensity is the amount of energy passing through a specified area in a specified amount of time and can be affected by frequency and the number of photons. However, brightness is not directly proportional to the number of photons. Instead, it is influenced by the way our eyes perceive color and the technology used to capture and display it.
  • #71
sophiecentaur said:
You are clearly in the early stages of learning about physics and I recommend you get the basics sorted out before coming to shaky conclusions.

I find your condescending remarks are funny. I recommend you stop talking about me, it's unnecessary. Just address what I say, directly, point out what you believe is wrong and tell us what you think is correct... or ignore it.
This stuff would never have been sorted out if it had been approached in a careless and uninformed way.

http://en.wikipedia.org/wiki/Intensity_(physics)
...intensity can mean any of radiant intensity, luminous intensity or irradiance, depending on the background of the person using the term.

- "And so God scattered them upon the face of the Earth and confused their languages, so they would never ever, ever get back together." -- This stuff is indeed handled in a careless and uninformed way.
This is a discussion forum and not a free tuition service. Any help you may get is your good fortune and not a right.

Aha. Let me help you understand then. I am developing a simulator to visualize these relations between light source, emitted light, lens, image and its consequent brightness. In order to do that I must model light as photons. Ok? Now, there is simply no other way to go about it but to define intensity, flux and brightness in terms of 'number of photons', and I will do it with or without your help. I guarantee you that this can be done if simplify the scenario by having the light source emit photons of the same energy, and if you help me it will happen sooner rather than later. My friend, it's take it or leave it. Your comments about my person are inappropriate, it's all up to you whether you are going to help or not, so suit yourself and please stop whining about it already.
 
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  • #72
Drakkith said:
The way we've been using brightness, yes. But be aware that brightness is a very bad term to describe light with. There are just too many different ways people use it. For example the way wikipedia uses it in your post is different than the way we've been using it.

That is why I keep saying brightness should not be defined as a property of light but as a property of an image. Then it will fit the definition from Wikipedia.
 
  • #73
tris_d said:
http://en.wikipedia.org/wiki/Intensity_(physics)
...intensity can mean any of radiant intensity, luminous intensity or irradiance, depending on the background of the person using the term.

Interesting that you chose to quote that link. I can't find any mention of a definition that involves photons in the whole of the web page. Can you? The only place the word turns up is in relation to the word "confusion". That rather proves my point.
 
  • #74
sophiecentaur said:
To avoid confusion, I have to point out that it is the other way round. The stars with the lowest visibility are given the highest magnitude value. Magnitude 1 corresponds to the apparent magnitude of Vega. The Sun, therefore, has a large Negative Magnitude. It makes sense as the stars with the highest magnitudes hadn't even been seen when the magnitude scale was first constructed.
Thanks for clarifying ... a high magnitude having a low number is poor phrasing.
Also, historically, the magnitude scale was introduced as a way to talk about brightness of stars in a sensible way.

Hopefully this didn't undermine the basic point that OP needs to pick meaning for the word "brightness" and stick to it. I see above that this message has not sunk in and OP continues to jump from one concept to another so much it is starting to look like trolling. At best he is observing that different writers use the word in different ways ... English is not the only language with this characteristic but it is especially famous for it. But what is wrong with that - as long as one is prepared to learn.

That is why I keep saying brightness should not be defined as a property of light but as a property of an image. Then it will fit the definition from Wikipedia.
Langauge does not work like that - "brightness" is not a scientifically rigorous term with a standard useage across disciplines or even within disciplines. People use words for their own convenience, not yours. What "should" or "should not" is neither here nor there - you have to deal with what "is" and "is not" and learn to live with it.

We can tell you what a particular use of the word means in a particular context, but don't go expecting the same meaning to apply in different contexts.

If you want to measure brightness as 255-<greyscale index> in an image [*], then go back to your original question: brightness is not related to wavelength (except as an equal mixture of rgb levels) and blue appears less bright than orange because of the way computer monitors are designed. Not quite what you wanted was it?

In defense: we do need to have flexible use terms in order to smooth communication when we are not being rigorous - or we'd all start to sound like published papers.

-----------------------

[*] iirc: that is the white index or "lightness" in an image.
Look in the filters of a decent photo-editor like GIMP or Photoshop and you'll see some defined as "brightness" and "luminoscity".
Fiddle with them and you'll see how those terms are defined in relation to an image - compare with your definition.
 
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  • #75
sophiecentaur said:
Interesting that you chose to quote that link. I can't find any mention of a definition that involves photons in the whole of the web page. Can you? The only place the word turns up is in relation to the word "confusion". That rather proves my point.

No, I don't see them, and therefore I have to make them. That is my point. My other other point is if we take light source is emitting photons of the same energy, then we can convert all those definitions to use number of photons instead of energy, or whatever they are using now. Would you agree?
 
  • #76
Simon Bridge said:
Langauge does not work like that - "brightness" is not a scientifically rigorous term with a standard useage across disciplines or even within disciplines. People use words for their own convenience, not yours. What "should" or "should not" is neither here nor there - you have to deal with what "is" and "is not" and learn to live with it.

We can tell you what a particular use of the word means in a particular context, but don't go expecting the same meaning to apply in different contexts.

I can tell you don't realize what I said. Look, if the source is emitting photons of the same energy, then the brightness of each pixel will be directly proportional to the number of photons that hits them and vary according to nothing else, yes?
 
  • #77
Ok this is ridiculous. This thread has been going on 5 pages now, mostly because of arguing back and forth over whether to use photons or not, and what "brightness" means. I feel we've argued both of those beasts to death. In WHATEVER model we use, whether it's photons or not, the end result is the same. The energy/number of photons fall with the inverse square of the distance.

Tris, since brightness apparently has absolutely no set meaning, if you want to use it to mean the value of the pixels in an image then go ahead. As long as however it is being used IS MADE CLEAR, I think we can all sleep at night.
 
  • #78
Drakkith said:
Ok this is ridiculous. This thread has been going on 5 pages now, mostly because of arguing back and forth over whether to use photons or not, and what "brightness" means. I feel we've argued both of those beasts to death. In WHATEVER model we use, whether it's photons or not, the end result is the same. The energy/number of photons fall with the inverse square of the distance.

Tris, since brightness apparently has absolutely no set meaning, if you want to use it to mean the value of the pixels in an image then go ahead. As long as however it is being used IS MADE CLEAR, I think we can all sleep at night.

I never meant for this to be any argument here, just to put all those definitions in the context of photons, and I expected you would help me do that. Never mind, I'll derive new definitions myself, if you can please just confirm whether this statement is correct: - If the source is emitting photons of the same energy, then the brightness of each pixel will be directly proportional to the number of photons that hits them and vary according to nothing else. True, false?
 
  • #79
If light source emits photons of the same energy, then:

1.) Radiant flux
= energy per unit time
=> number of photons per unit time

2.) Radiant intensity
= power per unit solid angle
= energy per unit time per unit solid angle
=> number of photons per unit time per unit solid angle

3.) Radiance
= power per unit solid angle per unit projected area
= energy per unit time per unit solid angle per unit projected area
=> number of photons per unit time per unit solid angle per unit projected area

4.) Irradiance
= power per unit incident area
= energy per unit time per unit incident area
=> number of photons per unit time per unit incident areaThis is basically what I need to do, plus somehow substitute 'unit pixel' instead of 'unit incident area' and/or 'unit projected area'. C'mon, my friends physics wizards, this is nice little fun problem to solve, for you... for me it's not, so help me!
 
  • #80
That looks fine to me. But I'm no expert.
 
  • #81
Drakkith said:
That looks fine to me. But I'm no expert.

I didn't even know flux and intensity are two different things until you told me the other day. I don't think it's about knowledge, information can be googled out, but understanding can not. I think to solve this properly the most important thing is to have understanding what originally those definitions represent, what they relate to, and regarding that you are expert compared to me. -- Can you tell me what 'incident area" relates to in definition of "irradiance", is it about area on the light source, area on the lens, or area on the image, or some other area? That's kind of stuff I need help with, to understand what is what and how it works, how it relates.
 
  • #82
tris_d said:
I didn't even know flux and intensity are two different things until you told me the other day. I don't think it's about knowledge, information can be googled out, but understanding can not.

Edit: The issue isn't that you didn't know what they were, but that it seemed like you hadn't even given any effort to even look up anything on it.

Can you tell me what 'incident area" relates to in definition of "irradiance", is it about area on the light source, area on the lens, or area on the image, or some other area? That's kind of stuff I need help with, to understand what is what and how it works, how it relates.

The first two sentences in the wiki article explain it.

Irradiance is the power of electromagnetic radiation per unit area (radiative flux) incident on a surface. Radiant emittance or radiant exitance is the power per unit area radiated by a surface.


Do you know what incident and radiated mean?
 
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  • #83
tris_d said:
If the source is emitting photons of the same energy, then the brightness of each pixel will be directly proportional to the number of photons that hits them and vary according to nothing else.
You still have not defined "brightness". Anyway: the signal from the photo-receptor, to a monochromatic source, will be proportional to the number of incident photons. (The proportionality will depend on the photon energy in question.)

You'll have some software to convert the signal strength to some number - you could call that number "brightness" if you want. This will be a received, or perceived, brightness - which will vary with the distance to the source and the size of the pixel.

tris_d said:
If light source emits photons of the same energy, then:

1.) Radiant flux
2.) Radiant intensity
3.) Radiance

4.) Irradiance
1-3 are about the light that leaves a source - the unit areas here are on or about the source and light passes through it or originates on it. 4 is about the light that arrives - the area in question is the illuminated surface rather than the source. Different surfaces with the same irradience may have a range of brightnesses (according to their greyscale number when photographed) depending on surface characteristics like color.
This is basically what I need to do, plus somehow substitute 'unit pixel' instead of 'unit incident area' and/or 'unit projected area'. C'mon, my friends physics wizards, this is nice little fun problem to solve, for you... for me it's not, so help me!
You need to find the area of a pixel. The detector will have an aperture, and some mechanism to spread the light through the aperture to a CCD array. You need to know how many pixels are in the CCD array, and how much of the light through the aperture is intercepted by it, and the area of the aperture.

You need to be conscious of the different "unit area"'s in the definitions above - they are different places.

Even better would be to state the problem you are trying to solve by making these definitions. Different problems will involve different methods and different concepts. How would you expect to use the data from a "brightness detector"?
 
  • #84
Drakkith said:
The issue isn't that you didn't know what they were, but that



The first two sentences in the wiki article explain it.

Irradiance is the power of electromagnetic radiation per unit area (radiative flux) incident on a surface. Radiant emittance or radiant exitance is the power per unit area radiated by a surface.


Do you know what incident and radiated mean?

English is not my first language, so I'd hate to assume. I guess 'radiated' refers to area on a light source from which light is emitted, and 'incident' relates to either lens area or projected are on the image. But I wouldn't bet more than $10 bucks my guess is correct, and if I try to interpret it like that, then "radiation per unit area incident on a surface" doesn't really make sense.
 
  • #85
tris_d said:
English is not my first language, so I'd hate to assume. I guess 'radiated' refers to area on a light source from which light is emitted, and 'incident' relates to either lens area or projected are on the image. But I wouldn't bet more than $10 bucks my guess is correct, and if I try to interpret it like that, then "radiation per unit area incident on a surface" doesn't really make sense.

No, you are correct. A light source radiates light outwards from it. The light incident on a surface falls on the surface and is absorbed, reflected, whatever. It just means that a certain amount of radiation falls on each unit of area of the surface. It could be square meter, or square centimeter, or whatever unit you are using. IE 100 watts/m2.
 
  • #86
Simon Bridge said:
1-3 are about the light that leaves a source - the unit areas here are on or about the source and light passes through it or originates on it. 4 is about the light that arrives - the area in question is the illuminated surface rather than the source. Different surfaces with the same irradience may have a range of brightnesses (according to their greyscale number when photographed) depending on surface characteristics like color.

Thank you! That's exactly kind of stuff I want to understand.

You need to find the area of a pixel. The detector will have an aperture, and some mechanism to spread the light through the aperture to a CCD array. You need to know how many pixels are in the CCD array, and how much of the light through the aperture is intercepted by it, and the area of the aperture.

You need to be conscious of the different "unit area"'s in the definitions above - they are different places.

Now we talking. Yes, I have to model all that is relevant, so yes, I see now I will need to define pixel size in order to relate it to "area" given in meters squared. One other question is how to model lenses, focal point and such, but I think that will become obvious when I understand more of how other things come into play and depend on each other. -- I used to be a game programmer by the way, so I'm pretty sure I could simulate and animate all that, as long as I understand how it works.
Even better would be to state the problem you are trying to solve by making these definitions. Different problems will involve different methods and different concepts.
How would you expect to use the data from a "brightness detector"?

I decided to make this in relation to my crackpot theory for Olbers' paradox, but since then I became really curious to understand how all of it works. And perhaps such program might be useful to astronomers and photographers, maybe to calculate what kind of equipment and settings would be the best for certain situations, or something. Basically, it's not about solving problems but about satisfying curiosity, and it is also about entertainment since I enjoy making software, especially if it challenges me and makes me learn new things.
 
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  • #87
Drakkith said:
No, you are correct. A light source radiates light outwards from it. The light incident on a surface falls on the surface and is absorbed, reflected, whatever. It just means that a certain amount of radiation falls on each unit of area of the surface. It could be square meter, or square centimeter, or whatever unit you are using. IE 100 watts/m2.

Great, thank you. So, does that mean irradiance and 'incident area' relates to lens area, to aperture size? While radiance and 'projected area' refers to area on the image and is relative to magnification and focus?
 
  • #88
tris_d said:
Great, thank you. So, does that mean irradiance and 'incident area' relates to lens area, to aperture size?

What do you think?

While radiance and 'projected area' refers to area on the image and is relative to magnification and focus?

I don't know.
 
  • #89
tris_d said:
One other question is how to model lenses
Depends on what sort of brightness detector you are talking about.

Lenses are normally simulated in computers using a transfer matrix or by ray tracing ... but you could get away with just stating that the lens arrangement spreads the light through the aperture evenly over the surface of the detector.
Basically, it's not about solving problems but about satisfying curiosity,
But you still have to have a context for the information or it is meaningless
 
  • #90
Drakkith said:
What do you think?

I think aperture size must be in the equation somewhere, so by the logic of reduction I find that one fits description the best.
 
  • #91
tris_d said:
I think aperture size must be in the equation somewhere, so by the logic of reduction I find that one fits description the best.

Yes, the aperture would be an "imaginary" surface if you like. You could find the total irradiance coming into your optical system using the area of the aperture.
 
  • #92
Simon Bridge said:
Depends on what sort of brightness detector you are talking about.

Lenses are normally simulated in computers using a transfer matrix or by ray tracing ... but you could get away with just stating that the lens arrangement spreads the light through the aperture evenly over the surface of the detector.

Yeah, I think for the lens it would be enough to model some "scale" proportion, that is some magnification property that will define how small or large projected image needs to be, in relation to focal point and aperture size, and whatever else is there that comes into equation. I still haven't started to think about it properly since I have yet to learn how all those parameters relate to each other.


But you still have to have a context for the information or it is meaningless

I'm not sure what do you mean, but here is what I got so far in relation to objects and their properties:

1.) Light sources:
- size, number of photons emitted, location/distance... anything else?

2.) Telescope:
- aperture size, exposure time, focus/magnification... anything else?

3.) Image:
- image size, pixel size, sensitivity, shades of gray... anything else?


So basically that's input defined by user, and output is an image of those light sources.
 
  • #93
It's a shame that so much time has been wasted on a notion for which there is no justification except an elementary gut reaction - i.e. the specifications of Luminance / Luminosity / Light Flux etc etc in terms of photons. I have looked quite hard but have found nothing to support it. Everywhere I look, these quantities are specified in terms of Power. Why persist with a basically flawed treatment of the topic? Do you really not see how wrong it is?

What is the point of indulging in non-Physics when, I should have thought, the aim is to learn something and improve your knowledge? Persisting with the Photon Thing is not helping Tris_d to learn what he needs to know.

Physics Forums is amongst the most scrupulous of discussion sites and our rules require contributors to avoid groundless speculation and the use of reputable references etc. etc. That's why people get involved with PF. You can see the rules by clicking the button at the top of this page. The way this is going is definitely contrary to the guidelines. There are many other forums on which anything vaguely scientific is acceptable. I suggest you go to them if that's really what you want.
 
  • #94
sophiecentaur said:
It's a shame that so much time has been wasted on a notion for which there is no justification except an elementary gut reaction - i.e. the specifications of Luminance / Luminosity / Light Flux etc etc in terms of photons. I have looked quite hard but have found nothing to support it. Everywhere I look, these quantities are specified in terms of Power. Why persist with a basically flawed treatment of the topic? Do you really not see how wrong it is?

You are wrong. I explained in post #71 what and why. The rest of the people understand, they've already helped me. I think I now know enough, just need to develop equations and after that I can write the simulator in one afternoon.


What is the point of indulging in non-Physics when, I should have thought, the aim is to learn something and improve your knowledge? Persisting with the Photon Thing is not helping Tris_d to learn what he needs to know.

Do you want to see how the simulator works once is done?

Physics Forums is amongst the most scrupulous of discussion sites and our rules require contributors to avoid groundless speculation and the use of reputable references etc. etc. That's why people get involved with PF. You can see the rules by clicking the button at the top of this page. The way this is going is definitely contrary to the guidelines. There are many other forums on which anything vaguely scientific is acceptable. I suggest you go to them if that's really what you want.

Here's scrupulous discussion for you...


If light source emits photons of the same energy, then:

1.) Radiant flux
= energy per unit time
=> number of photons per unit time True/False?

2.) Radiant intensity
= power per unit solid angle
= energy per unit time per unit solid angle
=> number of photons per unit time per unit solid angle True/False?

3.) Radiance
= power per unit solid angle per unit projected area
= energy per unit time per unit solid angle per unit projected area
=> number of photons per unit time per unit solid angle per unit projected area True/False?

4.) Irradiance
= power per unit incident area
= energy per unit time per unit incident area
=> number of photons per unit time per unit incident area True/False?
 
  • #95
I can find no references to justify your Photon Idea. You have not quoted any. Until you can, it is nonsense in terms of Physics.
You can make a simulator do anything you like. It doesn't need to be valid Physics. These pages are littered with the confusions caused for people who have believed what they have seen in a simulation. Your simulation could be very entertaining and fun to play with but it has no scientific significance. Fair enough and good if you don't claim any more than that.

One day you may learn more about Photons and you will realize where you are going wrong with your "=>" assertions. They are False and misleading.
 
  • #96
Sophie, remind me what assertions he is making? It seems more that he wants to "convert" energy into photons for the purpose of understanding the problem and developing a simulation.
 
  • #97
tris_d said:
You are wrong. I explained in post #71 what and why. The rest of the people understand, they've already helped me. I think I now know enough, just need to develop equations and after that I can write the simulator in one afternoon.

That reference has no mention of a formal definition in terms of numbers of photons. Have you actually read it all? Photon flux is actually mentioned in an entirely different context.

"^ Standards organizations recommend that radiometric quantities should be denoted with a suffix "e" (for "energetic") to avoid confusion with photometric or photon quantities."

You should try to go for a bit more rigour if you really want to be taken seriously. Most of what you need to know is in that reference and it is not actually about Photons. (The word occurs just twice: just in a footnote)
 
  • #98
Drakkith said:
Sophie, remind me what assertions he is making? It seems more that he wants to "convert" energy into photons for the purpose of understanding the problem and developing a simulation.
He seems to want to equate number of photons with the energy. Now, as photons of different wavelengths have different energies and very few light sources are monochromatic, the number of photons per second for a given Energy Flux density will not be the same for two sources with different spectra (e.g. red and blue stars). As far as I'm concerned, that knocks the Photon Thing totally on the head for serious use in comparing luminosities (or whatever related quantity you choose).

I realize that, for a simulation, it may be very convenient just to use a number but that's just not Physics. His simulation could work if he is only dealing with a notional light source which has the same spectrum throughout. But he seems to want the whole of Science to revolve around his wish to simplify. The daft thing is that he could just as easily use a variable called Power as a variable called Numberofphotons. But I think it has become too much of a matter of misplaced principle for him to do that simple thing.

That is the problem, I think. Understanding can only be claimed when what you think you've understood holds up against external criteria. Without that, it can easily be misunderstanding. Simulations 'prove' nothing. They can be smoke and mirrors.
 
  • #99
I honestly don't see the big deal, but I really don't feel like explaining why. It's been a long, frustrating, confusing thread that I think I'm done with.
 
  • #100
sophiecentaur said:
I can find no references to justify your Photon Idea. You have not quoted any. Until you can, it is nonsense in terms of Physics.

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

You can make a simulator do anything you like. It doesn't need to be valid Physics. These pages are littered with the confusions caused for people who have believed what they have seen in a simulation. Your simulation could be very entertaining and fun to play with but it has no scientific significance. Fair enough and good if you don't claim any more than that.

Mine will use valid physics though, and will be exact as much as this equation is:

d07def13d6f88776fe72fd064c75f820.png


One day you may learn more about Photons and you will realize where you are going wrong with your "=>" assertions. They are False and misleading.

Don't blame me for your inability to understand. Here's something for you to practice:Power to photon rate:
http://www.calctool.org/CALC/chem/photochemistry/power_photons

Energy to no. photons:
http://www.calctool.org/CALC/chem/photochemistry/energy_photons
 
  • #101
So, now you know the relationship between power and wavelength (and frequency) and it has taken 100 posts for that to emerge. (This is no news to most people on this Forum and it's what I suggested you should find out about, way back in this thread.) Can you not see that the power in the light from an arbitrary source cannot just equate to a particular number of photons per second - because the photons all have different energies. You need to know the particular proportions of each wavelength (i.e. the spectrum) in order to work out the Power - photon rate relationship. Can you get your head round that? What wavelengths do you intend to use? Will your light source be monchromatic? That's not a very useful model to simulate. If, on the other hand, you use Power Flux, the problem (and my objection) disappears. If you're clever enough to put a bit of computer code together then this should be a piece of cake.

Btw, did you not read my bit about E = hf, about a hundred years ago on this thread?
 
  • #102
sophiecentaur said:
Can you not see that the power in the light from an arbitrary source cannot just equate to a particular number of photons per second - because the photons all have different energies.

#59
- "Perhaps if we want to simplify or if the source emits photons of the same energy, ok? And then intensity would be directly proportional to the number of photons, wouldn't it?"

#71
- "I guarantee you that this can be done if simplify the scenario by having the light source emit photons of the same energy..."

#75
- "My other other point is if we take light source is emitting photons of the same energy, then we can convert all those definitions to use number of photons instead of energy..."

#94
- "
If light source emits photons of the same energy, then:

1.) Radiant flux
= energy per unit time
=> number of photons per unit time True/False?

2.) Radiant intensity
= power per unit solid angle
= energy per unit time per unit solid angle
=> number of photons per unit time per unit solid angle True/False?

3.) Radiance
= power per unit solid angle per unit projected area
= energy per unit time per unit solid angle per unit projected area
=> number of photons per unit time per unit solid angle per unit projected area True/False?

4.) Irradiance
= power per unit incident area
= energy per unit time per unit incident area
=> number of photons per unit time per unit incident area True/False?
"

Can you get your head round that?

Are your blind, or something? See above.


What wavelengths do you intend to use?

Defined by user or imported from a database with actual measurements.


Will your light source be monchromatic?

For start each light source will emits only photons of the same energy.


That's not a very useful model to simulate.

You wouldn't know.


If, on the other hand, you use Power Flux, the problem (and my objection) disappears. If you're clever enough to put a bit of computer code together then this should be a piece of cake.

Your objection is only your problem. It is necessary to quantize the light into photons because the image is quantized into pixels.


Btw, did you not read my bit about E = hf, about a hundred years ago on this thread?

Yes, thank you. Time flies, eh?
 
  • #103
The pixel and the photon issue are totally separate issues. However, because you are implementing your simulation in terms of discrete quantities, you may feel pressured into the quantised way of thinking.

I can't think of many light sources of interest (certainly not cosmic ones) that are monochromatic (why not use the right word, eh?) Funnily enough, if you were to be addressing the problem of laser light, you would really be forced into using a wave approach, which would add complication.
 
  • #104
sophiecentaur said:
The pixel and the photon issue are totally separate issues. However, because you are implementing your simulation in terms of discrete quantities, you may feel pressured into the quantised way of thinking.

How else would you calculate brightness per pixel?


I can't think of many light sources of interest (certainly not cosmic ones) that are monochromatic (why not use the right word, eh?)

It's about stars and galaxies, and in actuality I guess they do not emit monochromatic light, but if it can be approximated by taking an average, or if the actual measurements are already approximated in such way, then that should be good enough for me too.

Besides, I could make light sources output any range of photons with different wavelengths in whatever proportion, if necessary. It's just a matter of how actual measurements look like, which I'm in the process of figuring out right now by looking at star databases and the way they present such information.


Funnily enough, if you were to be addressing the problem of laser light, you would really be forced into using a wave approach, which would add complication.

I thought lasers are monochromatic and that intensity of a laser is therefore directly proportional to the number of photons emitted.
 
  • #105
Yes. Laser light is monochromatic but it is so coherent that it can produce speckles and patterns that 'ordinary' light sources do not. It would be difficult to model (except that your beloved photons per second per sqmetre would actually apply)

You
guess they do not emit monochromatic light
? Well, that was my whole point. There is a 2:1 ratio of energies of the shortest and longest wavelength photons. It is hardly worth my writing all this again - it's all in earlier posts - but you will surely appreciate the difference between what you get when you count photons and what you get when you measure the energy, for different coloured stars. The accepted way of doing this will take away this problem. Star Magnitude is based on energy flow, so why not just join the club?
There is no more to be said, really. If you want your simulation to be as real as possible then why not just specify things more conventionally? As I have also said before - the actual code would be hardly any different and you would have learned something at the same time.
 
<h2>1. What is the relationship between wavelength and brightness?</h2><p>The relationship between wavelength and brightness is known as Wien's displacement law. It states that the peak wavelength of radiation emitted by an object is inversely proportional to its temperature. This means that as the wavelength decreases, the brightness increases.</p><h2>2. Why does the brightness increase as the wavelength decreases?</h2><p>This is because shorter wavelengths have higher energy levels, which means they carry more energy. As a result, when an object emits radiation at shorter wavelengths, it appears brighter to us.</p><h2>3. Is there a specific wavelength that is the brightest?</h2><p>Yes, the peak wavelength of an object is the brightest. This is known as the peak emission wavelength and it can be calculated using Wien's displacement law.</p><h2>4. Can the relationship between wavelength and brightness be seen in everyday life?</h2><p>Yes, the relationship between wavelength and brightness can be seen in everyday life. For example, the sun appears brightest at shorter wavelengths, such as blue and violet, while objects like fire emit radiation at longer wavelengths, appearing less bright to us.</p><h2>5. How does the relationship between wavelength and brightness relate to the color of light?</h2><p>The color of light is determined by its wavelength. As mentioned before, shorter wavelengths appear bluer and brighter, while longer wavelengths appear redder and less bright. This is why objects with higher temperatures, such as the sun, emit bluer and brighter light, while cooler objects emit redder and less bright light.</p>

1. What is the relationship between wavelength and brightness?

The relationship between wavelength and brightness is known as Wien's displacement law. It states that the peak wavelength of radiation emitted by an object is inversely proportional to its temperature. This means that as the wavelength decreases, the brightness increases.

2. Why does the brightness increase as the wavelength decreases?

This is because shorter wavelengths have higher energy levels, which means they carry more energy. As a result, when an object emits radiation at shorter wavelengths, it appears brighter to us.

3. Is there a specific wavelength that is the brightest?

Yes, the peak wavelength of an object is the brightest. This is known as the peak emission wavelength and it can be calculated using Wien's displacement law.

4. Can the relationship between wavelength and brightness be seen in everyday life?

Yes, the relationship between wavelength and brightness can be seen in everyday life. For example, the sun appears brightest at shorter wavelengths, such as blue and violet, while objects like fire emit radiation at longer wavelengths, appearing less bright to us.

5. How does the relationship between wavelength and brightness relate to the color of light?

The color of light is determined by its wavelength. As mentioned before, shorter wavelengths appear bluer and brighter, while longer wavelengths appear redder and less bright. This is why objects with higher temperatures, such as the sun, emit bluer and brighter light, while cooler objects emit redder and less bright light.

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