Because its life or death depends on a system whose laws are described by quantum mechanics. In classical physics, a wave describing a musical tone can be seen as several waves with different frequencies that are added together, superposed. The next diagram shows the same circuit with one voltage source turne… To turn off a voltage source, you replace it with a short circuit.Circuit A contains two voltage sources, vs1 and vs2, and you want to find the output voltage vo across the 10-kΩ resistor. Log in here. Trying to understand what "both dead and alive" means ... Before studying quantum mechanics, the idea that something can be two things at the same time looks quite weird. Pred ball=Number of red balls extractedNumber of balls extracted.P_{\text{red ball}}=\frac{\text{Number of red balls extracted}}{\text{Number of balls extracted}}.Pred ball​=Number of balls extractedNumber of red balls extracted​. It can be in a superposition of the two values, with the probability that we subsequently measure it to have one value or the other depending on the details of the superposition. This is how quantum probability works. The system, just like the LCD ball, can be in a superposition of more states at the same time, hence both switched on and off, black and white, dead and alive. Similarly, a quantum state in superposition can be seen as a linear combination of other distinct quantum states. Not being able to see all the balls inside, we do not know which color the ball we pull out it's going to be until we see it, but we know for sure that if we see a red ball, that must have been a red ball even when it was inside the box. While we could in principle break the classical box and count every single ball to know the probability, we can not break our LCD ball, because the probability of seeing a color is not given by our ignorance of the details of our system (aka the number of the balls of each color) but it is an a priori probability, which is intrinsic of the ball. Superposition is one of the fundamental principles of quantum mechanics. Why would be a cat both "dead and alive" then? Sign up, Existing user? Let's now imagine that we have an LCD ball, just one, inside the box. New user? Let's try to convince ourselves that it's not. From our point of view, there is no difference between the two systems, because when we watch a ball, we see a color, and we can measure the probability of each color to be seen. Superposition is the ability of a quantum system to be in multiple states at the same time until it is measured. Let's imagine we have a box full of balls of different colors. Note that it is just a paradox that the cat is either dead or alive, and the reason is that quantum mechanics does not work on systems bigger than a bunch of atoms. Log in. This is how classical probability works. For instance, an electron that is white is in an equal superposition of being hard and soft, as the probability of measuring each value of hardness is equal. With the help of superposition, you can break down the complex circuit shown here into two simpler circuits that have just one voltage source each. If we want to make a prediction on which color will be the next ball, we can define the probability like the ratio between the total number of balls extracted and the number of extracted balls of that color: When we pull the ball out, the device detects we grabbed it, and not only it stops mixing colors, but it also makes all the balls of one color among those allowed. The superposition theorem is used in circuits that have mutiple power sources (2 or more power sources). This allows for easier analysis than when considering all of the power sources all at once. https://brilliant.org/wiki/quantum-superposition-for-dummies/. Nevertheless, there is a deeper difference. Sign up to read all wikis and quizzes in math, science, and engineering topics. The system, just like the LCD ball, can be in a superposition of more states at the same time, hence both switched on and off, black and white, dead and alive.