Can sorting be compared to matrix computation?

I have a question about two articles recently on HN. In one of them a physicist says that

"There is no computer on Earth that could possibly store such a big matrix in its memory"

On the other Google says that they sorted "1PB (10 trillion 100-byte records) on 4,000 computers" in six hours.

I know one is talking about matrix computation the other sorting. But is there a way to compare these two to verify if what the physicist claims is wrong and that google could actually store and make that computation?

Thanks

http://www.newscientist.com/article/dn16095-its-confirmed-matter-is-merely-vacuum-fluctuations.html

Virtual quarks make the calculations much more complicated, involving a matrix of more than 10,000 trillion numbers, says Stephan Dürr of the John von Neumann Institute for Computing in Jülich, Germany, who led the team.

"There is no computer on Earth that could possibly store such a big matrix in its memory," Dürr told New Scientist, "so some trickery goes into evaluating it."

http://googleblog.blogspot.com/2008/11/sorting-1pb-with-mapreduce.html

It took six hours and two minutes to sort 1PB (10 trillion 100-byte records) on 4,000 computers.