Why computers can't generate truly random numbers?

Answer 1

because the computer itself is a deterministic system that can't produce non-deterministic values.
but , as I learned here recently, you can create truly random numbers by audio sound that you receive via a microphone. but then again this means that not the computer itself creates the random number (because it's still a deterministic system) but the world outside it and the random number is created only with the help of the computer but not by the computer itself.
so basically, a computer as a whole can't create a truly random number since it's a deterministic system. But if you open up the system and introduce a non-deterministic system, e.g. the random noise of the outside world, then it's possible to create truly random numbers.

Answer 2

. @Thanh-le ..Thanks for the answer.