A lot of the Orion's Arm setting technology is based on magnetic monopoles and their derived super-material, magmatter. This allows megastructures like Niven Rings and such. It's very dense technobabbble, so I'm not sure how much is supported by real physics and how much is their invention, but it's a fairly hard science take on it.
Their ideas on
monopoles here, and
magmatter here.
PS: The magmatter text was written by a Luke Campbell, who I believe is on here as lwcamp, so you could ask him directly.