Sensitivity of Human Eye to Visible Light

Yes! Things appear coloured to an observer because colour corresponds with a property of light that is visible to the human eye.

Yes! Visible light is a form of electromagnetic radiation.

Our eyes respond so well to sunlight because of its intensity and because it contains all wavelengths of visible light.

Yes! The cornea is the transparent surface that covers the iris and pupil.

Photo-transduction takes place when rod and cone cells in the human eye convert their chemical response to light into electrical signals ready to input into the visual system.

Visual perception is the human ability to see and understand our surroundings by virtue of the sensitivity of our eyes to wavelengths of light across the entire visible spectrum, from red to violet.

• Visual perception is a complex process that relies on the intricate interaction between our eyes, the brain, and the interpretation of light signals. It enables us to perceive various visual attributes such as shapes, sizes, textures, depths, motions, and spatial relationships, all of which contribute to our comprehensive understanding and interpretation of the visual world around us.

• The observer effect is a principle of physics and states that any interaction between a particle and a measuring device will inevitably change the state of the particle. This is because the act of measurement itself imposes a disturbance on the particle’s wave function, which is the mathematical description of its state.
• The concept of observation refers to the act of engaging with an electron or other particle, achieved through measuring its position or momentum.
• In the context of quantum mechanics, observation isn’t a passive undertaking, observation actively alters a particle’s state.
• This means that any kind of interaction with an atom, or with one of its constituent particles, that provides insight into its state results in a change to that state. The act of observation is always intrusive and will always change the state of the object being observed.
• It can be challenging to reconcile this with our daily experience, where we believe we can observe things without inducing any change in them.

A photon is a particle that carries electromagnetic radiation. It is the fundamental unit of light.

• Thinking of photons as particles is useful for understanding the quantum nature of light.
• In the world of quantum physics, photons are the fundamental constituents of all forms of electromagnetic radiation, including light. They serve as the carriers of the electromagnetic force.
• Photons are elementary particles that have no mass and no electric charge. They are the quanta of the electromagnetic field, which is the fundamental field that describes electromagnetic interactions. Electromagnetic radiation, including light, is a manifestation of the electromagnetic field.
• Photons are the carriers of electromagnetic force because they are the only particles that can mediate electromagnetic interactions. When two charged particles interact electromagnetically, they exchange photons. The exchange of photons gives rise to the electromagnetic force.<
• Photons have no rest mass and always travel at the speed of light in a vacuum.
• Photons exhibit both wave-like and particle-like properties, a characteristic referred to as wave-particle duality. This duality is inherent to quantum particles, causing light to behave as a wave under certain conditions, as both waves and photons in others, and strictly as particles in yet others.

A human observer is a person who engages in observation by watching things.

• In the presence of visible light, an observer perceives colour because the retina at the back of the human eye is sensitive to wavelengths of light that fall within the visible part of the electromagnetic spectrum.
• The visual experience of colour is associated with words such as red, blue, yellow, etc.
• The retina’s response to visible light can be described in terms of wavelength, frequency and brightness.
• Other properties of the world around us must be inferred from light patterns.
• An observation can take many forms such as:
  • Watching an ocean sunset or the sky at night.
  • Studying a baby’s face.
  • Exploring something that can’t be seen by collecting data from an instrument or machine.
  • Experimenting in a laboratory setting.

 

Interneurons are a type of neuron found in the nervous system of animals, including humans, which play a role in processing and communicating information.

• Interneurons can be classified into different types based on their functions, such as local circuit interneurons and relay interneurons.
• Local circuit interneurons have short axons and form circuits with nearby neurons to analyse and process information locally.
• Relay interneurons have long axons and connect circuits of neurons in different regions of the central nervous system, enabling communication and integration of information.
• Interneurons can be further classified into sub-classes based on their neurotransmitter type, morphology, and connectivity.
• Interneurons serve as nodes within neural circuits, enabling communication and integration of sensory and motor information between the peripheral nervous system and the central nervous system.

A virtual photon is a theoretical concept in particle physics. Virtual photons are thought to be particles that exist for an incredibly brief time and cannot be directly observed. Their existence is inferred through their role in mediating interactions between other particles.

• Virtual photons are created when two charged particles interact with each other. For example, when two electrons interact with each other, they can exchange a virtual photon. This exchange of a virtual photon causes the electrons to repel each other. The electric force that we observe is thought to be due to the exchange of virtual photons between charged particles.
• Virtual photons are thought to play a role in many different physical phenomena, including the electromagnetic force, the weak force, and the strong force.
• More generally, a photon is a particle that carries electromagnetic radiation. It is the fundamental unit of light.