"As a student of the martial arts, I was taught to do this by focusing on a point in space that is beyond the bottom of the block. "

It is well to keep in mind be aware of what the point of this is. This is a technique for focus, to help avoid letting up on the blow at the point of contact. The hand, the arm, and the brick ALL still obey the laws of physics!
I actually knew a guy once who did Karate and broke things like that. He did a few boards one night, then someone said there was a piece of marble he could try...."sure!", he agreed....well, he set that marble up and hit it hard, twice....and hurt his hand. The lady who owned the marble then appeared and allowed as how he was lucky he did NOT break it!

   Having a method of focus, or a metaphor for explaining a feeling or technique is certainly useful, but it is all to easy to attribute the result to the 'mind' and forget that there absolute, though hard to measure, limits on what can be done. The ability to control mind focus and utilize bio-feedback can allow many amazing things...but we are learning more everyday about to to measure & understand the physics & chemistry imvolved.