Science is inherently a series of experiments within closed systems. A known starting points, then a prediction on what will happen based on a set of starting parameters. Once the prediction can be reproduced this is gauged as fact.
The universe itself is a system, which in essence had starting parameters, which as a common consensus is deemed to be 'The Big Bang'.
Predicting how a series of 50 coin flips will turn out (either heads or tails or edge) is nigh on impossible. Each flip takes into account many parameters (the force of the flip, height from the floor, air pressure, side winds, floor material etc). The coin doesn't have free will, but it is 'controlled' by the parameters at any one time. The starting parameters dictate how it will fall.
As you go through life, each decision you make, every action you take is predetermined by previous parameters, which each could be seen as 'starting' parameters for the specific time in place you are.
If you are at a turning, you can go either left or right. You think about it, you rely on experience, your memories to dictate which way you will go. Is left to a meeting which you are late for? Is right to the toilet? Do you know that going left is dangerous?
These questions go through your mind based on what you know and what you need to know about the 'choice' you have.
You wouldn't turn left if you knew you would die. You wouldn't turn right if the meeting room was to the left and you were late for a meeting there. Unless another factor overrides that. Maybe you need the toilet more than going to the meeting.
Therefore I propose that there is no such thing as free will. Everything is determined by what has happened previously. Even if you were in sensory deprivation (with no idea of what is to the left or right) and had to make a choice, you would base it on previous experience.
Free will is an illusion which is dictated by previous experience. Free will is only an assumption. Personal perception of history dictates your movements and choices.
Freedom is a myth. Though evidence does exist, which could mean proof of the opposite.