You can create some sort of device that monitors a completely random natural event and sends its results to the computer. For example, you could place a piece of radioactive material in front of a Geiger counter and connect the Geiger counter to a computer. Since radioactive decay is random, the Geiger counter would create truly random numbers.
I personally think that a computer algorithm can be designed to determine every set of variables in the universe because it is a computer science which it is a step by step calculations. I personally think that a computer algorithm can be designed to determine every set of variables in the universe because it goes into detail about computer science.
That would be one massive undertaking though. While it could be possible, one would have to figure with the size of the universe, it would take an infinite amount of time to achieve. There might be better things to spend our time and money on. Until we figured out everything else, this one should probably be put on hold.
The known universe is vast, mysterious and difficult at times to understand. It is important to try to understand as many variables that exist in it as scientists can define and identify, but it may not be that important to try to computerize everything. Computer algorithms can define and support a vast array of previously unknown phenomena, but it is probably in our best interests to leave some things to mystery. Many things are beyond our current capacity for understanding, and it is completely unfathomable that a computer algorithm would be able to determine every single variable.
I do not think we will ever be able to comprehend what every set of variables in the universe, let alone have a computer algorithm that would be able to determine them. You have to design a machine like this in the first place, and I think that alone would be nearly impossible.