A red shift, as defined by The Humbled Blue Orb definition by David Klein, is defined in two ways; sound-wise and light-wise. Light-wise is when an object’s light shifts more into the red side of the spectrum, which happens when the light’s wavelength is increased. Wavelength is how deep into the spectrum an object is from the center of the spectrum, as shown by the image below. All light that is being affected by photons and nothing else is a white light, which is the center of this image (even though it’s not visible). The more photons an object has the brighter it becomes, making the object have more energy, also meaning the deeper and darker light is less photons and less energy. Therefore, a light-wise red shift is when an object is losing energy and photons, and will soon run out.
This loss of energy is commonly referred to as “dying”, AKA a massive explosion of light and gas. If you haven’t guessed yet, red shifts almost only happen to stars, which are enormous balls of photons and gas that have a frequency dependent on the star’s mass. The frequency of a star is the sound-wise red shift, which is alike to the light-wise red shift but relating entirely to the Doppler Effect. The Doppler Effect is a measurement of distance using the strength of sound from a mobile object as heard by a stationary object. For example, when you’re on the sidewalk waiting for the walkie-man to turn green, cars will pass by you usually at around 20-30 miles per hour. At this speed, you can hear the distant sound of a car engine approaching you, which is the first of three stages of a red shift. As the car comes closer to you, the sound increases, then for the brief moment that the car is directly in front of you is when the car is the loudest. This is the second stage of a red shift. Then the last stage will be the same as the first stage in reverse; the sound of the car slowly becomes more distant, until it can’t be heard at all. This image is an example of how the Doppler Effect and light wavelength are very much alike.
Quasars
When a star dies, its contents are spilled out into the universe in the form of a gigantic explosion 3 times the size of our solar system. This occurs because when the star was active the force of the gas, heat, and photons were forcing themselves outwards, while still being in a ball. Meanwhile, the mass of the gas created an enormous gravitational force, causing the gasses, heat, and photons to be forced into a more condensed form, meaning both forces were equally powerful on each other; thus, making the star stable. As the star aged, the gas used to create the incredible amount of light and heat the star emitted depleted. This means that the force of the gas became weaker than the force of the heat and photons, making the star unbalanced. Because the gas’ mass shrank, the star’s size increased because the gas, heat, and photons were no longer being held together as tightly. The star aged more, the star got bigger, and the heat and light being exerted decreased until the opposing forces became so unbalanced the star exploded, leaving anything in its path a gassy mess of heat and light.
Although, this is what happens when a normal, small, or large sized star dies; what happens to the largest star known, the red hypergiant, is much different. As a hypergiant is born, large enough to fit over 1000 sun’s inside it, the mass is so great its light can be seen from tens of thousands of light years away. If you were to look up at the stars at night in the middle of the Sahara Desert, you could see the largest star known; VY Canis Majoris. Its luminosity is so great, it’s brighter than any other star we can see from Earth, even though it’s roughly 5,000 light years away. As a red hypergiant, VY Canis Majoris’ luminosity is one of the brightest things in the universe; but VY Canis Majoris was brighter at birth. When the hypergiant is first born, the light is white, and is brighter than it is now, at one million years old; then as it gets older, the color gets darker, up until it’s red, which is the mark of a Red Giant, the stage VY Canis Majoris is at now. This is a phase that every star will go through at the end of its life, when the star becomes nearly three times its original size. For a hypergiant, three times its original size is far beyond anything the laws of physics can handle, causing the red hypergiant to collapse on itself, being compressed to less than one percent its original size. Something this small can’t be handled by the laws of physics either, and will collapse on itself once more. Now the hypergiant has reached the point of no return, and the bringer of no returns; a black hole. The black hole is a vacuum, annihilating anything in its path and turning it into a stringy, unidentifiable version of its original self. This is called Spaghettification: when an object experiences a gravitational force so great it turns the object into a stringy, skinny version of itself. Spaghettification also wrings all of the contents out of the object like a toothpaste bottle, including any photos, energy, or gas within it. That said, when the black hole consumes something like a star, the gas and light is extorted back out of the black hole and everywhere around the black hole, causing the gases and light to orbit the black hole. This is what’s called a Quasar. Below is a picture of a black hole sucking up a star and becoming a quasar.