prompter: Why cant we see infrared light?

assistant: We can't see infrared light because the human eye is only able to detect light in the visible spectrum, which ranges from about 400 to 700 nanometers in wavelength. Infrared light has longer wavelengths than visible light, typically ranging from about 700 nanometers to 1 millimeter. This means that the energy of infrared light is lower than that of visible light, and our eyes are not sensitive enough to detect it. However, many animals, such as snakes and some insects, can see infrared light, and humans have developed technology, such as infrared cameras, that allow us to "see" in the infrared range.

prompter: Are there other types of light we can't see?

assistant: Visible light spectrum is 380 to 700 nanometers, anything outside of that will not be visible to the average human eye.

assistant: We can see red light, this is the lowest energy light with the longest wavelength, followed by orange, yellow, green, blue, and violet.

assistant: Infrared light is a type of electromagnetic radiation with a wavelength longer than visible light, which means that it has lower energy and lower frequency than visible light. Our eyes can only detect a narrow range of electromagnetic radiation known as the visible spectrum, which includes light with wavelengths ranging from about 400 to 700 nanometers.
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Infrared radiation, with wavelengths ranging from about 750 nanometers to 1 millimeter, is beyond the range of what our eyes can detect. This is because our eyes are not sensitive to the specific frequencies of infrared radiation, so we are not able to see it. However, many animals, such as snakes, have specialized organs that can detect infrared radiation, which they use for hunting and navigation. Additionally, special cameras and equipment can detect and visualize infrared radiation, which can be useful in fields such as astronomy, military and security, and medicine.

prompter: Why are our eyes not sensitive to it, while other animal's are?

assistant: The sensitivity of an animal's eyes to different types of electromagnetic radiation depends on the anatomy and physiology of their eyes. In the case of infrared radiation, many animals have evolved specialized structures that can detect the heat generated by infrared radiation. These structures are called pit organs or heat-sensing pits, and they are found in animals such as snakes, pit vipers, and vampire bats.

These pit organs contain temperature-sensitive cells that respond to infrared radiation by producing electrical signals, which are then processed by the animal's brain to create an image of their surroundings. In contrast, our eyes are not equipped with these specialized structures, which is why we are not able to detect infrared radiation naturally.

However, humans have developed various technologies, such as thermal imaging cameras, that can detect and visualize infrared radiation. These technologies work by converting the heat generated by infrared radiation into an image that can be seen by the human eye or processed by a computer.

assistant: Our eyes are not sensitive to infrared because most of the world emits it. We would see everything that is even slightly warm, our vision would look like what you can see on a heat map camera. Some animals though, such as Mosquitoes and vampire bats do have slight infrared vision in order to be able to see in the dark.

assistant: Our brains and nerves work based on electrical impulses, which are little bursts of electrical current. Electricity is what happens when you remove the electrons from one atom or molecule and move them to another one nearby. In some materials, like metals or heavily ionized liquids like blood, it's easy to move electrons around and make electrical current flow. In other materials, like plastic or rubber or bone, it's harder to make the electrons move.

It takes energy to make an electron move away from an atom. In conductors, it takes only a little energy; in insulators, it takes a lot of energy. How much energy it takes to liberate an electron is called the "work function" or the "ionization energy," depending on exactly what you're doing, and is measured in volts. (Well, technically it's electron-volts, but that compound word makes people fall instantly asleep.) If you push the same number of electrons --- the same current --- out of a nine-volt battery, you do about six times the amount of work of a 1.5-volt AA battery.

If you hit an atom with some energy but it's not enough to knock the electron completely free, you can sometimes make the electrons around the atom vibrate. But the atom can't vibrate any old way: only certain frequencies are allowed. If you try to give an atom energy in some amount that's not allowed, the atom's electrons just ignore you. It's kind of like finding a vending machine that says "quarters only": if you have a pocketful of dimes and dollar coins, then too bad for you.

We happen to live in a world where ionization energies for stuff are typically three or five or ten volts, and electronic excitation energies are typically one or two or three volts.

Light is the way that electric charges exchange energy with each other. Light comes in lumps, called "photons," which each carry a certain amount of energy. It turns out that the energy in each lump is directly related to its color: violet light has more energy per lump than blue, blue more than green, green more than yellow, yellow more than red, and red more than infrared. When visible light hits the pigment proteins in the retina, it makes the electrons vibrate; that sets in motion the machinery to send an electrical impulse to your brain. When ultraviolet light hits those pigment molecules it ionizes them, which makes the molecules fall apart and sets in motion a different mechanism ("cleanup on aisle four"). And when infrared light hits those pigment molecules, it doesn't have enough energy to make the electronic vibrations go, so you get zero information about the infrared light: you're at the vending machine, but only with dimes. Visible light photons have energies from about 1.8 volts (red) to about 3 volts (violet).

The whole story is more complicated than this because the different ways a molecule can vibrate depend very sensitively on its shape, but that's the basic idea. This is also why ultraviolet light is more dangerous than visible light: in addition to breaking up pigment molecules, ultraviolet photons have enough energy to break up DNA molecules.

Infrared light can make an entire molecule vibrate, which is what we call heat. (It's easier to make a whole molecule vibrate because molecules are big and floppy, while the electrons are held near their atoms on a short, stiff leash.) The pit snakes have a delicate membrane which seems to detect radiant heat by causing warmed air to flow through a pore; you can see right away that this thermo-mechanical sense is completely different from the electro-optical method that we (and the eyed snakes) use to see visible light.

prompter: Thanks but can you make explain it more briefly and simply please?

assistant: Humans are not able to see infrared light because it has a longer wavelength than visible light and our eyes are not sensitive to this wavelength. Infrared light is outside the range of wavelengths that our eyes can detect. To see infrared light, you need a special camera that can detect this wavelength.