Time is a physical magnitude that affects all reality, but we do not have a specific sense to perceive the intervals. This makes each person get a different idea about the nature of time. There is no consensus on what time is.
1- Heraclitus of Ephesus (philosopher): becoming flows like a river, it is the Being.
2- Parmenides of Elea (philosopher): there are no changes, there is no time.
3- Aristotle of Estagira (philosopher): time exists when movement involves a number.
4- Galileo Galilei (physicist): movement is relative. If A moves with respect to B, B moves with respect to A.
5- Isaac Newton (physicist): time is real and absolute.
6- Immanuel Kant (philosopher): time is an a priori form.
7- Albert Einstein (physicist): time is an illusion and relative.
8- Henri Bergson (philosopher): rejected mathematical time.
9- Martin Heidegger (philosopher): time is the being-there or dasein, time is temporary.
10- Julian Barbour (physicist): time does not exist.
11- Paul Davies (physicist): defends the unidirectionality or arrow of time.
12- José Ignacio Latorre (physicist): time is a parameter that relates two movements.
13- Lee Smolin (physicist): time is real.
14- Bradford Skow (philosopher): past, present and future coexist in the universe.
15- David Eagleman (neurobiologist): time is invented by the brain.
16- Elvis Sibilia (psychologist): time is magnitive, that is, objective, imperceptible and measurable.
Meaning of colors:
Blue: time exists (5)
Black: intermediate (5)
Red: time does not exist (6)