It's possibly no coincidence that Hillary Clinton started her presidential run the same week that astronomical scientists at the University of Hawaii in Manoa announced the discovery of a Supervoid, a structure in space 18 billion light-years across and "distinguished by its unusual emptiness." The Supervoid sits in a part of the cosmos known as the Cold Spot, where there's far less matter to observe than elsewhere throughout the universe.

It's a perfect analogy for how Hillary Clinton's opponents seek to characterize her: as someone who is profoundly visible yet hard to identify. She is politics' Dark Matter: We know she's there, but we just can't describe her. Is she on the left or the right, is she a friend of the rich or the poor, is she a testosterone-fueled superhawk or a grandmatronly van-driver popping into Chipotle for a chat with the staff?

Yet Hillary's identity problem is prominent only because she has been on the public stage for so long. It's a magnified version of a debilitating crisis of identity that sits at the heart of national American politics, the real Supervoid that constricts and confines most presidential candidates: and that is, the intense pressure to say nothing. Knowing that your every speech and interview sits in the digital archive, ready to be analyzed by an army of opponents with time to spare and money to spend, can kill spontaneity dead. Far better to sit contentious debates out. If you hold public office, be careful how you vote on any piece of legislation, no matter how obscure. Your voting record will be used by your opponents just as savagely as if it were a criminal one.

This is the ultimate Supervoid now at the heart of politics. It's the reason why for most presiden­tial candidates today, the only significant thing they can say about themselves is that they are running for president.