That's not that new an idea. Even at 1% of c we could fully colonize the Milky Way in 10 million years, which is a blink of an eye compared to the >4B years the EArth has been here.
The second issue is that planets don't really matter other than being essentially "mass repositories". They're a highly inefficient way of creating living area. I'm speaking of course of Dyson Swarms as a highly likely alternative. I saw "highly likely" because it requires no new physics, no new materials beyond what we already have, is orders of magnitude more efficient (in living space per unit mass terms) and is essentially just an engineering problem (obviously a big one).
If you accept that premise then it's even less likely there are other spacefaring civilizations within our light cone because they would stick out like a sore thumb. Certainly a whole galaxy of these would be detectable by us currently from millions of light years away.
The second issue is that planets don't really matter other than being essentially "mass repositories". They're a highly inefficient way of creating living area. I'm speaking of course of Dyson Swarms as a highly likely alternative. I saw "highly likely" because it requires no new physics, no new materials beyond what we already have, is orders of magnitude more efficient (in living space per unit mass terms) and is essentially just an engineering problem (obviously a big one).
If you accept that premise then it's even less likely there are other spacefaring civilizations within our light cone because they would stick out like a sore thumb. Certainly a whole galaxy of these would be detectable by us currently from millions of light years away.