That could be detected by looking for a particular pattern of polarized light in the cosmic microwave background, known as B - mode polarization. (latimes.com)
Theoretical models also predict how black holes with their disks and jets look like in polarized light. (blackholecam.org)
Krugman's one of the most polarizing figures in economics, but no matter what you think of him, his tweets (which send you to his blog) are guaranteed to make you think. (businessinsider.com)