The beginners guide to light!

exchemist said:
There are two questions here.

Visible light -indeed any light - is the product of an emission process from matter that generates radiation. There are two of these processes: spontaneous and stimulated. Spontaneous emission does not require radiation to be present - it is just given off by matter in an excited state. Stimulated emission is radiation given from matter in an excited state when pre-existing radiation interacts with it. A famous example of this is the laser.

However your first question is what makes certain wavelengths of light visible to us. That is the result of the electrochemical signal produced, when light in the range of wavelengths our retinas are sensitive to strikes it. The sensitivity range is determined by the photochemistry of the retina, specifically the "photopigments" present in the light detection cells of the retina.

So this is to do, not with how light is emitted but how it absorbed, in the eye. I do not know exactly what happens to these photopigments after they absorb a photon of the right wavelength, but I imagine they will produce an excited state of the pigment molecule, which will then release its energy, somehow, in a chemical form that is ultimately converted to a signal in the optic nerve. (I am not a biochemist.)
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Thank you for your reply .

How does the appearance of an object, its colour and shape, transfer itself to a mirror?
 
amber said:
Yes mirrors reflect light, that does not explain how the image of the object travels through the space to the mirror. Do you know how that works?
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Ah ha! I can't remember your banned name off the top of my head but your strange statement "how the image of the object travels through the space to the mirror", tells me who you are... just can't quite remember the name. I'll bet exchemist gets it!
 
origin said:
Ah ha! I can't remember your banned name off the top of my head but your strange statement "how the image of the object travels through the space to the mirror", tells me who you are... just can't quite remember the name. I'll bet exchemist gets it!
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I have no idea what you are talking about, please do not mistake me for being somebody else, especially if this person is a man.
 
amber said:
I have no idea what you are talking about, please do not mistake me for being somebody else, especially if this person is a man.
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Have no idea the gender of anybody on this site, well, I'm pretty sure of my own gender and the mods I suppose.
 
origin said:
Have no idea the gender of anybody on this site, well, I'm pretty sure of my own gender and the mods I suppose.
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Back to the topic, we can place a mirror in any position around an object , facing the object and the mirror will show an image. Quite clearly the image of the object is in some way travelling across the space to the mirror. Where does the colour go while the image travels through the space?
 
origin said:
The language of science is very precise. With out using the correct terms you cannot effectively convey the proper meaning. So your definition above is not correct because you introduced the term magnitude.
The term magnitude as it relates to light is about the apparent brightness of a celestial object when observed with the naked eye.

Just stick with the proper term - intensity.

Edit to add: If you really want to put it in common language you could say the brightness decreases as the inverse square of distance.
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yes, please explain as i am curious too. if you have a two-way mirror that is bouncing off photons traveling toward infinity, what happens to those particular photons when you change the direction of the mirrors or remove them altoghether? suspended in space-time?

if no one really knows. they can just say, 'i don't know'.
 
amber said:
Back to the topic, we can place a mirror in any position around an object , facing the object and the mirror will show an image.
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Golly it really is quite confusing isn't it. It's like magic!!!

Quite clearly the image of the object is in some way travelling across the space to the mirror.
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How do you think this totally amazing feat is accomplished??

Where does the colour go while the image travels through the space?
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Whoa, that is really profound! Does it go into another dimension? Does it just disappear and then reappear? I'll bet it is quantum vibrational entanglement!!
 
birch said:
yes, please explain as i am curious too. if you have a two-way mirror that is bouncing off photons traveling toward infinity, what happens to those particular photons when you change the direction of the mirrors or remove them altoghether? suspended in space-time?
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The photons continue on their path. What is the point of the 2 way mirror in you question?
 
birch said:
how can they if you remove the mirrors? toward what trajectory are they continuing toward?
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Light is being reflected off of you in all directions. If someone holds a mirror up in front of you some of the photons from you will reflect off of the mirror. All of the photon that are reflected off of the mirror will continue on their path until they hit something. If you remove the mirror all of the reflected photons that did not hit something will continue on their way. Don't try to make this complicated it is very straight forward.

Why did you say remove the mirrors. Are you asking about 2 mirrors? A 2 way mirror is a single mirror that is only partially reflective and allows some light to travel through the mirror.
 
amber said:
Have you ever read Hubble's law before you make an assumption?
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Yes but I ignored it as it did not suit my cosmology.
Is that wrong?
amber said:
So what basis do you have to consider space is expanding?
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It seems a fundamental part of the current prevailing cosmology model the big bang theory and that is the basis upon which I consider the Universe is expanding.
But I prefer a model where space does not expand and is in effect steady state but observations seem to make that model unsupported.
So there is a lot I must ignore to support my preferred model.
Is that wrong?
Alex
 
origin said:
All of the photon that are reflected off of the mirror will continue on their path until they hit something.
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if you have two mirrors facing eachother where the photons are going into apparent infinity, what happens to those particular photons when you drape a cloth over both mirrors?

doesn't it mean they are trapped in the mirror and technically in a different dimension?
 
origin said:
How do you think this totally amazing feat is accomplished??
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I think it is obviously light related but something we cannot see.


Whoa, that is really profound! Does it go into another dimension? Does it just disappear and then reappear? I'll bet it is quantum vibrational entanglement!!
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I would not like to speculate , please tell me more about your quantum vibration entanglement?
 
Xelasnave.1947 said:
Yes but I ignored it as it did not suit my cosmology.
Is that wrong?

It seems a fundamental part of the current prevailing cosmology model the big bang theory and that is the basis upon which I consider the Universe is expanding.
But I prefer a model where space does not expand and is in effect steady state but observations seem to make that model unsupported.
So there is a lot I must ignore to support my preferred model.
Is that wrong?
Alex
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I consider the observed evidence points towards an observational expansion rather than of space itself. I understand that the BB model describes an expanding Universe, however the model ignores the non-observable space beyond the expansion. Light from distant bodies that are in expansion, does not only travel towards our observation, it also travels the opposite direction into the non-observable Universe.
Boundaries based on light intensity do not need an edge or in a sense an expanding Firmament. To say space itself is expanding is liking to placing an expanding glass dome around our observation.
 
amber said:
I consider the observed evidence points towards an observational expansion rather than of space itself. I understand that the BB model describes an expanding Universe, however the model ignores the non-observable space beyond the expansion. Light from distant bodies that are in expansion, does not only travel towards our observation, it also travels the opposite direction into the non-observable Universe.
Boundaries based on light intensity do not need an edge or in a sense an expanding Firmament. To say space itself is expanding is liking to placing an expanding glass dome around our observation.
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expansion is measured from the the increasing expansion/distance between celestial bodies, not by how much space can be observed based on continuing light distance.
 
birch said:
expansion is measured from the the increasing expansion/distance between celestial bodies, not by how much space can be observed based on continuing light distance.
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There is a huge difference in something travelling away from an observer and an expanding edge of space. Only one of the differences can be correct. The Hubble observes red shift of bodies/galaxies, there is nothing evident that suggest space itself is expanding. Based on evidence I personally prefer to think that Galaxies are simply moving away from us into more space.
 
birch said:
if you have two mirrors facing eachother where the photons are going into apparent infinity, what happens to those particular photons when you drape a cloth over both mirrors?

doesn't it mean they are trapped in the mirror and technically in a different dimension?
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That would be cool if they were trapped, but alas all that happens is that the photons will be absorbed into the mirror or scattered and it takes nanoseconds for this to happen. There is no such thing as a perfect mirror, if there were such a thing as 2 absolutely perfect mirrors, aligned absolutely perfectly and they were in an absolutely perfect vacuum, I suppose it is possible that the photons would just bounce back and forth between the mirrors. But that is a completely unreal set up.

As far as another dimension, lets not forget your reflection is not real (it is not a physical person) so how could that be trapped in another dimension.
 
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