Yet more questions about light

From the top...

The general relationship between (rest) mass m, momentum p and energy E is this:
\(E^2=(pc)^2+(mc^2)^2\)
A photon has $m=0$, but it has energy $E=pc$, related to its momentum. Also $E=hf$ for a photon, where $h$ is Planck's constant. So photons have energy related to their frequency.

It is not. Kinetic energy and rest mass energy are two separate things.

The waves have different frequencies and different amplitudes, so changing either of these changes the information coming in. In practice, when we look at the world we see many different frequencies of light, with different levels of brightness.

Maybe. What do you mean by "processing the data", exactly?

Lots of additional "processing" of "data" happens in the brain.

As the combinations of light waves hitting out eyes vary in intensity and frequencies, our brains do interpret those changes in various ways. We infer motion from certain patterns of change, certainly.

Whichever you want. Or, more accurately, it depends on what aspect of the "hitting" you're trying to describe.

Colour is, more properly, the frequency of the light. There are complications, though. The colour purple is a mixture of different frequencies (red and blue). There is no "purple frequency".

Light does not have to eject electrons from atoms or molecules in order to have an effect on them.

It depends what kind of light you're talking about. Light of a single, constant frequency carries no information. It can't be used to transmit any kind of message from one place to another. To transmit a message, some aspect of the light has to vary with time.

You're talking about sensory information? Most human beings rely extensively on their sense of sight, of course, but we have other senses.

You still need a brain to make any sense of that perfect image.

There are sources of light. There are objects that reflect light. The eyes collect emitted and reflected light. The retina converts detected light into electrical signals, which the brain interprets.

How deep do you want to dig into the "how" of all this?

The information of everything it has reflected off is not retained by the light. Each detected photon only carries information about whatever it was that emitted it, most recently.

 

I'll just record my agreement with all of the other people here who have explained to you that you're using the word "hallucinate" incorrectly.

A hallucination is a false perception - a perception of something that has no external (to the brain) physical cause.

When we see colour, there is stimulus of the visual cortex of the brain, often due to light entering the eye.

 

"Hallucinated" is the wrong word. Our concious perceptions are constructed by the brain, certainly, but perceptions based on real external events (such as light hitting the retina of the eye) are not hallucinations.

It depends what you mean by "accurate". Your TV set only has three kinds of coloured LEDs: red, green and blue. Nevertheless, it can fool your brain into seeing 16 million+ colours.

That's not what "hallucination" means. None of our senses provide "direct" information, in the way you're using that term.

That's a very strange thing to say. Science is in the business of examining natural phenomena and trying to explain them. It is an empirical endeavour.

What on earth do you mean by saying that science excludes any trace of a "phenomenal experience"?

What "phenomenal content" is there, other than that which we can observe? What are you talking about?

No. Scientific theories of colour (as opposed merely to the properties of light) are necessarily concerned with how we perceive things, which necessitates a consideration of mental processes.

Red light and the human perception of red are two different things. Science has investigated both of them.

When you see a red rose, there is light reflecting off the rose that produces a particular sensory experience in your brain. There is an unbroken chain of causation from the photons coming off the rose to your eventual conscious perception of its red colour.

Is it your contention that there's something more to "red" than the physical processes that process the information from the light and convert it to a sensory perception? If so, how can you show that the "extra" thing - whatever you think it is - actually exists?

Science posits many things that are not directly accessible to our senses. We cannot see electrons, for instance. However, we can still infer their existence by performing certain experiments and interpreting the results.

The task of science is to build explanatory theoretical models of the natural world, which allow us to predict how systems will behave in future, under various conditions.

Yes, sensations are generated by our brains. That's why they are called sensations: they require our senses and they require our consciousness.

We humans are an inherent trait of the physical universe. Our vision is what it is. I don't believe anybody said it was "necessary" to be that way, rather than some other way.

Do you want to compare your separate subjective perceptions of the colour yellow? There's no way to do that directly.

We're all part of the objective physical world.

 

It depends what you mean when you say something is "colored". We can define yellow light to be light that contains photons in a particular range of wavelengths, for example. If we do that, then yellow photons are yellow photons, objectively distinguishable from red photons or blue photons.

Even if you want to define "colored" as something like "producing a subjective sensation that people refer to using a particular colour word", then we can still say that yellow photons are yellow, because they produce the subjective sensation of yellow. There might well be several different ways to produce the same subjective visual sensation of yellow, but most of them are going to involve photons of some kind.

Yes. Particular sensations don't exist until we experience them, and they go away when we're no longer experiencing them.

No. Red photons impinging on your eye won't usually cause the sensation of yellow, for instance. The sensation of yellow is most commonly produced by light in the world that has the appropriate properties to stimulate the correct brain cells etc.

If that were true, then it would be impossible to correlate subjective reports of colours with particular wavelengths of light. And yet, we can do that. There are repeatable correlations between the sensations people report and the objectively observable physical processes that are occurring.

Nobody claims that colour perception is due only to objective properties to be found in light. The clue is in the name: colour perception. You can't just ignore how the perception part is working.

Again, "hallucination" is the wrong word. Scientists have a good understanding of the physical reasons for why these kinds of complementary colour perceptions happen under the right conditions. It's partly due to the colour cones in the eye becoming 'saturated' and taking some time to regain their normal resting state.

Perhaps. But you should definitely stop using the word "hallucination", which is clearly an incorrect description of what is happening.

The molecules in the banana reflect light that is perceived as yellow. If you want to abbreviate that description, I guess you can say the molecules are yellow, because when we give the colour of something we're almost always implying something about the way it emits or reflects light or transmits light.

Voltage is a measure of energy per unit charge, which has nothing to do with colour, so no.

What do you understand by the term "qualia"? Can you show that qualia exist?

 

Most accurately, it is a key constituent of a theoretical model used to describe electromagnetic radiation.

There is a smallest unit of light possible at any given frequency. That unit is a photon. You can have 1 photon, or 7 photons or 500 billion photons, but you can't have 1.5 photons, or 6.8 photons or half a photon. The term "quanta" refers merely to this fact that that light comes in discrete units. There's nothing circular about that.

The light coming into your eye each second usually contains enormous numbers of photons. Not mere billions. More like thousands of billions of billions.

When it behaves in particle-like ways, it makes sense to refer to it as a particle.

In a sense, we already have. Our best models of matter and light have as their fundamental constituents quantum objects that, under suitable conditions, exhibit either the properties of macroscopic particles or waves. The term that is usually used for this is wave-particle duality.

QFT goes a step further, describing all particles as excitations of fields that pervade all of space.

The concept of a photon does not posit that photons light is made of energy, or that light is a "substance". There is nothing circular here, as long as you are careful to define terms like "matter" appropriately. Depending on how you define that term, it might be true to say that matters is made of quarks (in part) or, if you define it a different way, to say that quarks are a kind of matter. But again, there's nothing circular. One thing is defined in terms of the other, and the definition only goes in one direction, not in circles.

No. Particle models posit fundamental entities. Molecules are made of atoms, which are made of protons, neutrons and electrons. Electrons aren't "made of" anything smaller. They are fundamental. Protons and neutrons are "made of" quarks, but quarks aren't "made of" anything smaller; they are fundamental.

So the 'assumptions' you mention - which aren't really assumptions, by the way, stop. It's not an endless regress.

You couldn't be more wrong.

Do you honestly think that somebody one day just said, at random, "I'm going to imagine that there are these things I'm going to call 'atoms', and I'm going to assume they are made of things I'm going to call 'protons', 'neutrons' and 'electrons'"?

That's not how science is done. For starters, protons, electrons and neutrons were all discovered, experimentally, at different times, decades apart. As theoretical elements of physical theory, they were necessitated by the results of many separate and disparate experiments.

In other words, the reason scientists believe in things like protons and electrons, these days, is precisely because of the vast body of empirical evidence for their existence.

It can only be through ignorance that you could claim that there is no empirical evidence for the existence of something like an electron. You've heard of electronics, right? What do you think is going on with that, exactly? What are electrical engineers working to control and exploit exactly? You must wonder. Or maybe you just take modern technology entirely for granted and don't think about how or why it works?

Yes.

No. The clue is right there: "irreducible substrate". The regress stops right there. It goes in one direction only. There is no circularity.

It doesn't go both ways. It only goes one way. Particles are described as excitations of fields. Never the reverse. No circularity.

 

A different theory with a different irreducible substrate. Not "made of nothing". The strings are the irreducible substrate. They don't "reduce" to anything more basic. Understand? In this theory, there is nothing and there are strings. The strings aren't made of the nothing, any more than quarks are made of nothing in the Standard Model of particle physics.