Obviously we can't "know" this.
My thinking is largely influenced by consciousness researcher and founder of Qualia Research Institute, Andrés Gómez Emilsson.
Here's a couple recent videos with him about why digital computers can't be sentient. https://www.youtube.com/watch?v=xJzBjBo24g8 https://www.youtube.com/watch?v=RT9tnzucnPU
How do you know that?