What do we really see?

[J. K.]

The more I thought about this one, the more my head hurt.

I was looking at the moon, planets, and stars last night. When we look at the moon, we're seeing the light of the sun reflected on it. Then the thought struck me. In reality, isn't light the only thing we see? In other words...we don't really see any physical object; we only see the light reflected from it.

An even worse headache came when I realized: because light has a measurable velocity, we are actually seeing into the past by a very tiny amount of time.

We can't see objects, and we can't see now. We're blind! Time for the aspirin . . .

Edited March 3, 2012 by J. K.

[karmakazi]

The more I thought about this one, the more my head hurt.

I was looking at the moon, planets, and stars last night. When we look at the moon, we're seeing the light of the sun reflected on it. Then the thought struck me. In reality, isn't light the only thing we see? In other words...we don't really see any physical object; we only see the light reflected from it.

An even worse headache came when I realized: because light has a measurable velocity, we are actually seeing into the past by a very tiny amount of time.

We can't see objects, and we can't see now. We're blind! Time for the aspirin . . .

Yes... light is in fact the only thing we see. If an object appears green, it is because it absorbs all of the light rays except for those which compose green, reflecting those back to our eyes. Things could have no color or solid appearance at all, but because light refracts from them it appears as if they do.

Fortunately for us, light is so fast that our minds cannot fathom how miniscule that time difference is. When we look at the sun we're looking slightly into the past, and when we look at the stars we're looking even more into the past. Hundreds of years of time are converging here, when we look to the sky.

Edited March 3, 2012 by karmakazi

[StarMountainKid]

Nice thought. We never do experience 'the thing itself', do we? In art, before the Impressionist movement in painting, artists used to paint trees, grass, water, clouds, etc. Then the Impressionists had this great new idea: instead of painting all these things, let's paint light!

Our brains create the world around us that we experience. If somehow we could become aware of the 'real' world, I think it would be nothing like the one we're used to experiencing.

Edited March 3, 2012 by StarMountainKid

[Abramelin]

You can go a step further: our brains manufacture an image, a 'thing', from what our eyes perceive.

It's electrical signals that certain cells in the retinas of our eyes send to our brains (the optical lobes) after fotons 'stimulated' them. The brains interpret, filter out this, add that, and voila: an image.

You can wonder about whether fish, insects, moluscs and so on see he same 'thing' as we do. Add to that that certain animals can perceive UV and infra-red light, and god knows what they see. And that would very probably not be the same as what we see with just an overlay of an UV and/or IR photo.

[Kryso]

The brain is a crazy thing. For example, you can see your nose all the time! But your brain filters it out. Problem is, it will now take about half an hour to stop noticing it now I've pointed it out, lol

[Landry]

Nice thought. We never do experience 'the thing itself', do we? In art, before the Impressionist movement in painting, artists used to paint trees, grass, water, clouds, etc. Then the Impressionists had this great new idea: instead of painting all these things, let's paint light!

Our brains create the world around us that we experience. If somehow we could become aware of the 'real' world, I think it would be nothing like the one we're used to experiencing.

StarMountainKid ... true that. What we think of a physical vision occurs in total darkness inside the brain. What's out there creates images on the retina of the eye which are then converted into nerve impulses and deciphered by the visual cortex, located in the back of the brain, in absolute darkness. Our brains are decoding nerve impulses (electricity) into what we perceive as vision.

Edited March 3, 2012 by Landry

[lightly]

good topic .. I wonder if it could be reasoned that electrical impulses in the brain are a form of light?

Being that, anything electrical is Electromagnetic in nature, and anything ElectroMagnetic in nature is a from of light?

[J. K.]

good topic .. I wonder if it could be reasoned that electrical impulses in the brain are a form of light?

Being that, anything electrical is Electromagnetic in nature, and anything ElectroMagnetic in nature is a from of light?

(Technically, it's the other way around, I think - light is part of the electromagnetic spectrum.)

It is true that we can see light that is generated by electricity - lightning, static electricity - but I don't think that electricity itself consists of photons. So would the neural impulses be visible as light, or a non-visible exchange of energy through neurons?

[jules99]

good topic .. I wonder if it could be reasoned that electrical impulses in the brain are a form of light?

Being that, anything electrical is Electromagnetic in nature, and anything ElectroMagnetic in nature is a from of light?

Hi;

I thought we had machines that show activity in different areas of the brain when different functions are performed, like reading or talking or whatever.

Also we have the ability to dream and use our imagination to create images in our minds eye..I dont know if this involves manipulating light but how could you dream or form a picture in your minds eye in total blackness?

[lightly]

hi Jules, i was thinking the same thing , an image in my mind seems like light... but , I dunno. Hi JK.. i'll answer your response the same way.. I DUNNO ... but i think, the Entire EM spectrum actually can be referred to as LIGHT... including the portion visible, to our eyes. As Abramelin said, we can't see infrared.. or ultra violet portions of the EM spectrum... but they are light.

I recently heard it said on some science program, by a supposed scientist, that Photons are the particle that carries the Electromagnetic force? i don't know if that is entirely true ... Also.. i can't understand how photons could accomplish Magnetic attraction or repulsion. ... i just like to think about some things.. i don't actually know much of anything. (see disclaimer below)

Some scientists keep looking for a Graviton .. a particle that carries the force of Gravity...

[Leonardo]

hi Jules, i was thinking the same thing , an image in my mind seems like light... but , I dunno. Hi JK.. i'll answer your response the same way.. I DUNNO ... but i think, the Entire EM spectrum actually can be referred to as LIGHT...

Not really, lightly. The EM spectrum consists of radiation, and light occupies the small band width of this spectrum we can perceive optically. Calling the entire spectrum 'light' would be a misnomer. 'Light' has a specific frequency, wavelength and energy in the EM spectrum.

including the portion visible, to our eyes. As Abramelin said, we can't see infrared.. or ultra violet portions of the EM spectrum... but they are light.

Infrared radiation is a form of heat radiation - not light. Ultraviolet is a bit more difficult to categorise as there is no general term, afaik, (such as 'light' or 'heat') applicable to it. It is commonly referred to as 'uv light', but it isn't really light.

[lightly]

Not really, lightly. The EM spectrum consists of radiation, and light occupies the small band width of this spectrum we can perceive optically. Calling the entire spectrum 'light' would be a misnomer. 'Light' has a specific frequency, wavelength and energy in the EM spectrum.

Infrared radiation is a form of heat radiation - not light. Ultraviolet is a bit more difficult to categorise as there is no general term, afaik, (such as 'light' or 'heat') applicable to it. It is commonly referred to as 'uv light', but it isn't really light.

Thank You Leonardo, for the correction. Yes, i guess that has long been the standard definition of light.... that portion of the electromagnetic spectrum which is visible to human eyes...

The portion of the EM spectrum that we can see is invariably referred to as VISIBLE LIGHT... as if to infer that portions on either side are invisible light?

I remember now, it was Physicist Brian Cox on the television series "Wonders of the Universe" saying that all radiation was a form of light and , oddly enough, i remember clearly him specifically saying that Heat is a form of light , as he was feeling heat rise from hot sand. I was surprised to hear him refer to heat as a form of light ... but he's the physicist?

I also have been told by a physicist/ UM member that more than strictly the visible portion of the EM spectrum can be referred to as light. Unfortunately I can't remember which portion of the UM spectrum we were discussing. So , i'm confused by conflicting descriptions from those much more knowledgeable than myself.,, as can be demonstrated by this statement on a NASA website which describes infrared radiation as light.

http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html

Infrared: Our skin emits infrared light, which is why we can be seen in the dark by someone using night vision goggles. In space, IR light maps the dust between stars.

[keithisco]

I think we tend to verify common objects around us using our other senses. With your eyes closed you can still determine the form of household items. Sight actually gives us a tele - scopic sense of things that we are not in physical contact with, the same with hearing. All senses interact to give a 3 dimensional "view" of our surroundings, without which we would have enormous difficulty in relating to our physical existence.

Going back to the OP.... Yes, everything we percieve is in the past. There is no "now", because light has a (probable) finite speed, and electrical synapses in the body, and nervous system particularly, depend on chemical reactions that are most certainly time - dependent for their functionality.

[Mr Right Wing]

The more I thought about this one, the more my head hurt.

I was looking at the moon, planets, and stars last night. When we look at the moon, we're seeing the light of the sun reflected on it. Then the thought struck me. In reality, isn't light the only thing we see? In other words...we don't really see any physical object; we only see the light reflected from it.

An even worse headache came when I realized: because light has a measurable velocity, we are actually seeing into the past by a very tiny amount of time.

We can't see objects, and we can't see now. We're blind! Time for the aspirin . . .

Even worse your brain only receives electrical signals from your senses not light.

The experience of colour, objects and images are constructed by your brain out of those electrical signals. What you call reality is in fact constructed by your mind.

To give you an even bigger headache people believe the brain is like a computer which produces our minds. For this to be true our minds would have to be confined inside our brains. Yet the reality you just realised is mind isnt confined to our brains it exists all around us.

Your mind exists outside of your head so how can it be a produced by your brain?

[Taun]

Not only can we only see 'the past' but we can only sense the past! Because our senses of touch, taste, hearing, smell all rely on transmitting impulses to the brain, then having the brain sort it out we actually can not sense the precise present in any way...

There is always at least a miniscule delay...

Never really though of it before - so... Great OP!

[sepulchrave]

that Photons are the particle that carries the Electromagnetic force? i don't know if that is entirely true ...

You are correct: it isn't ``entirely'' true.

It is true that the photon is the gauge boson that is the carrier of electromagnetic force. It is not true that one can detect a photon carrying this force.

Also.. i can't understand how photons could accomplish Magnetic attraction or repulsion. ... i just like to think about some things.. i don't actually know much of anything. (see disclaimer below) Some scientists keep looking for a Graviton .. a particle that carries the force of Gravity...

Same story.

In the context of Quantum Field Theory, all forces operate by the exchange of virtual particles. Using the language of Feynman Diagrams, this means that two electrons repelling each other via electrostatic force, would simultaneously:

1. Exchange 1 photon,
   
2. Exchange 2 photons,
   
3. Exchange 1 photon that splits into an electron and positron before recombining to a photon,
   
4. Exchange 1 photon that splits and then the electron and positron exchange a photon before recombining,
   
5. Exchange 1 photon that splits and then the electron and positron exchange a photon that splits before recombining and then the final pair recombine,
   
6. Exchange 2 photons, one of which splits and the electron absorbs the extra photon and the positron emits a photon and then the electron and positron recombine,
   
7. Etc.
   

In other words, to explain the simple electrostatic repulsion using gauge quanta like photons, one needs an infinite number of combinations.

There is experimental evidence to support this concept (for example the Casimir effect), but it probably easier for everyone to just think of forces as being carried by ``quasiparticles'' that can't be independently detected.

i remember clearly him specifically saying that Heat is a form of light , as he was feeling heat rise from hot sand. I was surprised to hear him refer to heat as a form of light ... but he's the physicist?

Heat isn't a form of light, but again the explanation is technical enough that Brian Cox can be forgiven for describing heat as a form of light.

Heat is a form of random kinetic energy; in solids this is usually in the form of vibrations. The infrared portion of the EM spectrum couples to vibrational and rotational modes in many solids and liquids, so absorbing infrared radiation increases the amount of heat in an object.

Technically, absorbing any form of energy will turn some of that energy into heat (slam your hand on the counter: it might feel a bit warmer, as would the counter top). However infrared radiation is easily absorbed and often the most easily converted into heat of any electromagnetic radiation; so it is acceptable to refer to infrared radiation as ``radiant heat''.

I also have been told by a physicist/ UM member that more than strictly the visible portion of the EM spectrum can be referred to as light. Unfortunately I can't remember which portion of the UM spectrum we were discussing.

The definition is pretty loose. Leonardo isn't wrong in saying that light is the visible part of the EM spectrum, but if you want to refer to every part as light very few scientists will be upset (or more importantly, not understand what you are saying).

[lightly]

Thanks sepulchrave , especially enjoyed smacking my hand on the counter and the resultant heat

.. some of the other info i'm just a bit dodgy on yet

[Edel]

Hi;

I thought we had machines that show activity in different areas of the brain when different functions are performed, like reading or talking or whatever.

Also we have the ability to dream and use our imagination to create images in our minds eye..I dont know if this involves manipulating light but how could you dream or form a picture in your minds eye in total blackness?

You can also reproduce sound/songs in your head in complete silence. It`s not sound. It`s mind power!

[Mr Right Wing]

Not only can we only see 'the past' but we can only sense the past! Because our senses of touch, taste, hearing, smell all rely on transmitting impulses to the brain, then having the brain sort it out we actually can not sense the precise present in any way...

There is always at least a miniscule delay...

Never really though of it before - so... Great OP!

I'm goona disagree with that because we have several options available -

1. External reality exists, our eyes receive information from it, electrical signals are sent to the brain and then our brain constructs our experience.

2. External reality doesnt exist everything is mind.

3. The mind is just perceptions, these perceptions bring into existance reality in such a way as to prop up their own existance. A bit like a feedback loop.

I believe in number 3 and think that changes to perception therefore alter reality.

[JayMark]

The thing with the brain and main concern of the topic is that from it's "point of view" everythingwe experienced as raw experience (5 senses) are really only informations converted into electrochemical activity (brain) and somehow it results in everything we see, hear, touch, taste or smell.

Now is the world real? I would say it's as real as we perceive it. If you ask "does matter creates consciousness?" it would be pretty hard to anwser. Consciousness is one if not the biggest mystery we know of. No matter what neurophysicists etc. know, no one can explain out of any doubt (as far as I know) how the hell all this activity generates consciousness. Where is the limit between brain activity and our consciosuness and if counsciousness is only really about electrochemical signals, how do we manage to perceive them as everything we perceive?

John Eccles, famous Nobel Prize winning neurophysicist already said: "I want you to know that there are no colors in the real world, there are no fragrances in the real world, that there’s no beauty and there’s no ugliness.

Out there beyond the limits of our perceptual apparatus is the erratically ambiguous and ceaselessly flowing quantum soup. And we’re almost like magicians in that in the very act of perception, we take that quantum soup and we convert it into the experience of material reality in our ordinary everyday waking state of consciousness."

[StarMountainKid]

Very nice post, JayMark, in my opinion. I would think the level of intelligence and the level of consciousness develop jointly in animals. The more intelligent an animal is, the more conscious it is of its environment and of itself.

I think we are conscious because we are our brain. The brain is constantly comparing its sensory input within itself. A feedback mechanism. I have an idea that somehow this self-referencing mechanism creates our consciousness, or is our consciousness. The brain being aware of itself.

[Stellar]

Not really, lightly. The EM spectrum consists of radiation, and light occupies the small band width of this spectrum we can perceive optically. Calling the entire spectrum 'light' would be a misnomer. 'Light' has a specific frequency, wavelength and energy in the EM spectrum.

It really depends on the context I guess. I refer to any part of the EM spectrum as "light" when dealing with physics all the time. Hell, if we're talking about visible light, we actually specificy "visible light".

In essence... light is an electromagnetic wave. The frequency of it doesn't change that it's light... just as "sound" refers to all sound, whether its audible or not.

I also have been told by a physicist/ UM member that more than strictly the visible portion of the EM spectrum can be referred to as light.

[JayMark]

Very nice post, JayMark, in my opinion. I would think the level of intelligence and the level of consciousness develop jointly in animals. The more intelligent an animal is, the more conscious it is of its environment and of itself.

I think we are conscious because we are our brain. The brain is constantly comparing its sensory input within itself. A feedback mechanism. I have an idea that somehow this self-referencing mechanism creates our consciousness, or is our consciousness. The brain being aware of itself.

I also agree with what you said. Couldn't have said it in a better way.

[Leonardo]

It really depends on the context I guess. I refer to any part of the EM spectrum as "light" when dealing with physics all the time. Hell, if we're talking about visible light, we actually specificy "visible light".

In essence... light is an electromagnetic wave. The frequency of it doesn't change that it's light... just as "sound" refers to all sound, whether its audible or not.

I understand and accept that many people use 'radiation' and 'light' interchangeably. Personally, I do not, but that might just be pedantry on my part.

[Von Bismarck]

Infrared radiation is a form of heat radiation - not light.

Leonardo isn't IR just light with a longer wavelength and lower frequency than visible light? So, basically it's still light but it's just not visible for the human eye?