Suppose a scientist who knows everything "physical" about color but has never seen it... It requires you to think about different ways of knowing and what constitutes understanding, aiming for a readable explanation without oversimplifying the depth of these concepts. One way to frame this, as explored in some sources, is through a thought experiment known as Mary the color scientist. Imagine Mary lives in a black-and-white environment but is the world's foremost expert on color physics, chemistry, and physiology. She knows everything about wavelengths, how light interacts with surfaces, the structure of the eye, the neural processing of color information in the brain, and so on. When she finally sees color for the first time, say a red rose, the question is: does she learn something new?. On a surface level, one perspective suggests that yes, she absolutely learns something new. This "new" thing isn't more facts _about_ color in the scientific sense – she already knows those. What she gains is the subjective _experience_ of color, the inner sensation of redness. This points to the idea that there might be a kind of knowledge or understanding that comes only through direct, conscious experience, something often referred to as _qualia_ (though the sources don't use this specific term). This perspective suggests a gap between knowing all the physical facts about color and knowing _what it is like_ to experience it. If this is the case, it raises questions about whether consciousness and subjective experience can be fully explained by purely physical facts, sometimes called the "hard problem" of consciousness. This idea resonates with distinctions found in the sources between different kinds of knowing. Bertrand Russell, for instance, differentiates between "acquaintance" and "knowledge by description". According to this view, you have acquaintance with something when you are directly aware of it, without needing inference or knowing truths about it. Seeing a color like blue is given as an example of acquaintance. You know the color itself "perfectly and completely" when you see it, and learning truths _about_ it doesn't enhance this direct knowledge _of_ it. In contrast, knowledge by description involves knowing truths about something. So, Mary had immense knowledge _by description_ about color, but lacked _acquaintance_ with it until she saw it. Her first visual experience would grant her this direct acquaintance. However, other perspectives presented in the sources challenge this conclusion regarding Mary. Some argue that the concept of having _complete_ physical knowledge is so profound that we underestimate what it would entail. Philosopher Daniel Dennett, for example, suggests that if Mary truly knew absolutely everything physical about the brain and how it processes color, she _would_ be able to deduce or discern the inner sensation of red _before_ experiencing it. In this view, seeing the red rose would merely confirm her prior expectations based on her complete scientific understanding. Another angle is that while Mary gains something, it might be better understood not as a new _fact_, but as a new _ability_. Philosophers like David Lewis and Laurence Nemirow propose that upon seeing red, Mary acquires the _ability_ to identify, remember, and imagine the inner experience of red, something she couldn't do before, but this doesn't mean she learned a new piece of factual information that wasn't already contained within her complete physical knowledge. Even Frank Jackson, the originator of the Mary thought experiment, reportedly changed his mind, suggesting that complete physical knowledge _would_ allow her to determine what it is like to see red, implying that the subjective experience isn't something separate from the physical facts. He suggests our usual reliance on direct experience to know what something is like leads us to wrongly assume this is the _only_ way to acquire such knowledge. The scientific approach to color, as described in the sources, often focuses on objective, measurable properties. Physics describes color in terms of wavelengths along a continuous spectrum. Different wavelengths correspond to different colors. Astrophysicists can analyze the light from distant objects using prisms or spectrographs to determine their chemical composition and temperature based on unique spectral patterns – essentially, they read the "color signatures" of elements, which are the same on Earth and in the sun. They have precise methods to quantify color using ratios of light measured through filters, avoiding the "messy business of human color perception". This objective, quantitative approach yields powerful knowledge _about_ color and what it reveals about the physical world. However, there's an acknowledgment that this objective description might feel "cold, colorless, and indifferent" compared to the subjective experience. There's also the point that "specific sense-qualities" like color cannot be directly mathematized like spatio-temporal properties, only indirectly, hinting that there might be something about these qualities that "evades all mathematization". Furthermore, perception isn't a purely passive reception of objective data. It involves an interplay between the object and the perceiving subject, influenced by factors like interests, expectations, and goals. Our brains apply assumptions about the world and lighting to interpret the ambiguous information received by the retina, constructing our sense of lightness and color. This suggests that what we perceive as color is not simply a raw, objective quality "given" to us, but is actively constructed based on sensory input and internal processing, guided by our embodied nature. So, when the scientist sees color for the first time, even with complete theoretical knowledge, the sources offer different ways to think about what happens. Does she: 1. Gain acquaintance with a subjective sensation (qualia) not reducible to physical facts, highlighting a limit of purely objective knowledge? 2. Simply confirm theoretical predictions she could have made with her complete physical knowledge? 3. Acquire a new ability related to the experience, rather than a new fact? 4. Experience a concrete aspect of reality that scientific abstraction aims to understand but doesn't replace? Ultimately, the sources present different facets of the complex relationship between objective, scientific knowledge and subjective, lived experience. While science excels at describing the physical nature of color and its effects, the question of whether _knowing_ what it is like to see color is included in that knowledge remains a point of philosophical debate, depending on how one defines knowledge, experience, and the relationship between the physical and the conscious. This discussion opens doors to exploring topics like phenomenology (the study of experience), the nature of consciousness, and epistemology (the theory of knowledge) in more depth.