How could we know? We just started detecting it, but can we say for sure it was happening before that?

But, most likely, odds-wise, it was happening for a long time. Now is not special except that you and I exist and that the tool was invented to detect this. It kinda makes sense that it was going on without our knowledge the day before, the week before, and 1000 years before. 10 billion years ago, I'm less confident about.

See Louisiana State University: Advanced Thin Ionization Calorimeter (ATIC) makes National News.

I don't undersand your confusion. What is to be confused about? Are there some contradictory facts you see?

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