You technoweenies bore me. Your arrogance causes a blindness as dark as the intergalactic spaces. You speak of the levels of civilization based on the level of energy usage or perhaps on the mastery of increasing smaller scales of matter, claiming this is what determines the future and nature of life, but it is not. Life is about the genes and survival strategies. What? Is that too hard for you so you revert to the comfort of your mechanisms? Please explain to me where life fits into your equations? It's simply not there and so your equations are obviously useless. Aliens might consider contacting us when instead of being animals at the whims of nature we control our own destinies enough to become something more. If you want a primer on how to become more than an animal, perhaps look at Genetics For A New Human Ecology https://www.amazon.com/dp/1544900996 Without understanding that, our civilization will be destroyed far sooner than 1500 years.