As a general rule, in many situations, we tend to let ourselves be led by common sense and logic, which are the same ones that dictate the parameters to think and decide based on a certain scenario.
However, sometimes, things end up being very different from what we thought at first, or directly, they defy common sense and logic, reaching the point of being impossible. This concept is called paradox.
Let's see a list of 04 very curious and interesting paradoxes, some of them quite well known:
The Schrödinger cat
One of my favorite paradoxes is the theoretical experiment of Schrödinger's cat. It belongs to the field of physics, more specifically that of quantum physics.
In the Schrödinger experiment, we have a totally opaque box, with 3 elements inside: a cat (alive), a bottle with a poisonous gas and an apparatus with a radioactive particle, which has a 50% chance of disintegrating.
In the case of disintegrating, the bottle releases the gas, killing the cat. In the case of not disintegrating, absolutely nothing happens (and the cat lives).
The paradox is that, according to our common sense, the cat will be alive or dead but we can not know until the box is opened. According to the laws of quantum physics, the cat is alive and dead (both states at the same time) until the box is opened and checked.
The paradox of grandfather
The paradox of the grandfather is a physical paradox very used in science fiction, since it has its base in the trips in the time. It is well known and has been used in many works, such as Terminator, Back to the Future or Futurama.
Assuming the case that a person could travel back in time, go back several years and kill his grandfather before he had offspring (specifically the father of the time traveler), this would not have been born or had children, so the time traveler would not be born nor would it be possible to travel in time to kill his grandfather.
It is curious how certain solutions to this paradox have been devised to make the event possible, such as the existence of parallel universes, alternative time lines or so many others. Another paradox related to science fiction
The paradox of the infinity hotel
The Infinite Hotel by Hilbert is a paradoxical metaphor related to the world of mathematics.
Two big businessmen with a giant hotel, have the problem that they want to guarantee customers that they will always have a room available for a new client. As the current hotel, with 1,000,000 rooms was not enough, they took matters into their own hands.
The two businessmen decided to build the first hotel with infinite rooms. An infinite number of rooms guaranteed hosting an infinite number of clients. But when a new client arrived, they saw themselves again with the same problem.
For this they devised a solution. Provide accommodation to clients with the only condition that if a new client arrives, they have to leave their room and go to the next room (+1). Thus, the new client would stay in room 1, and the rest would be rolled to the next room directly. As the hotel has an infinite number of rooms, there would be no last room.
The paradox of the snake
Finally, to finish, another popular paradox, very similar to that of the egg or the chicken, called The Paradox of the Serpent, widely used in fields and philosophy subjects.
A uróboro is a Greek word that represents an animal that engulfs its own tail, forming a circle. If that animal, for example, a snake, begins to eat its tail and ends up swallowing its whole body ... Where would the snake be?
The paradox comes into play when we realize that the snake is inside its own stomach, but simultaneously it continues to eat itself.
