How to understand all scientific propositions must have falsifiability, and theories that cannot be falsified cannot become scientific theories.

All scientific propositions must have falsifiability, that is, the possibility of being proved wrong. Without falsifiability, this proposition is neither right nor good, not even wrong, too vague, not a scientific proposition. For example, the lucky number of Aries today is 0, and no one can prove this right or wrong. Can be falsified, but there is no falsification. For example, aliens exist, which has not been confirmed yet. Can be falsified. For example, Aristotle thinks that the weight of an object is directly proportional to the speed of its free fall. This theory ruled for thousands of years, and was later broken by Galileo's experiment that two copper balls landed at the same time.