There’s been a fun video going around that demonstrates separating eggs using an empty water bottle. It is a lot of fun to do, but is not particularly efficient. And a few of us found that the bottle trick had about the same margin of error—that is, breaking the yolks—as traditional methods.
Cracking an egg and transferring the yolk back and forth between the egg shell halves is actually not a great way to separate eggs. The shards of egg shell can easily poke the yolk, causing it to get into the white. (Also: the outside of the egg shell may or may not be clean).
Your hand is a much gentler separator. Open the egg onto your very slightly separated fingers (palm up) and the white will slip down into the bowl.