What is the most compelling evidence against the idea of free will?

It could be argued that scientific research has shown the universe to be governed by inflexible and mathematically precise physical laws; in that sense, we live in a deterministic universe in which all things happen out of necessity. Therefore, even when we make decisions which we believe to be the result of our own free will, perhaps we were forced to make them, as a result of the various deterministic processes which make up our lives. Freedom would then be an illusion.