The article explicitly says that it's talking about number of spatial dimensions, it's not including time. It says the new theorem shows that black holes can f

The article explicitly says that it's talking about number of spatial dimensions, it's not including time. It says the new theorem shows that black holes can form into up to 7 spatial dimensions (plus 1 for time). (This isn't to say they can't form beyond that, just this new theorem doesn't show that.)