I saw the static version in Lawrence Krauss' "A Universe from Nothing." At his lecture last week, he used this animated GIF. If I understand it, this is a representation of virtual particles coming into and going out of existence in our Universe. They play a role in Krauss' overall argument regarding the possibility/probability of our Universe having been "created" from Nothing. The catch is that Nothing is not really "nothing" as we normally think of it. But I've only read his one book and haven't studied physics since Dr. Rolleigh's class back at Hendrix...we did not cover dark matter and virtual particles!