We fret every day about consumption, waste, and energy, and here are some people discussing methods of moving planet-sized objects. It's a kind of optimism that's so rare it almost feels outdated.
Unlike most of what is for sale in this world, which happens to be uninspiring garbage.
I'm afraid we have to keep fretting. In the Numberphile video about the number of particles in the Universe (https://youtu.be/lpj0E0a0mlU?t=378), they take an interesting diversion to ask "How long until every particle in the Universe is inside a human being?" In other words, when will we reach the ultimate limit to growth? Well, at the current annualized population growth, it's less than 9000 years! And that scenario involves every human being at that future time floating around naked in the vacuum of space. There is no food to eat, water to drink, nor air to breathe left over.
Practically, this means a couple of things that are less than obvious. First, the best case is that we will reach a point where the growth in volume of the space we occupy will exceed the speed of light. In other words, "long" before 9000 years from now, we will either establish some sort of equilibrium, or we will run up against a hard Malthusian limit. We will absolutely be concerned about "consumption, waste, and energy" in a way that is far more focused than it is now. (The only economic models that are permitted to work are zero-growth models, practically speaking.) Second, to give you an idea of how soon this is coming, the Universe is much larger than 9000 light-years across. That is to say, even if we could manage the resource usage of our 1.011% growth rate optimally, we could never actually fill the Universe in that time frame, as it would take about 15 billion years or so if we were all flinging ourselves outward at very near the speed of light. (n retrospect, these two are restatements of the same idea.)
Finally, and most dismally, the analogous calculation for the Solar System (an infinitely more reasonable calculation to perform) must be abysmally worse and monumentally more urgent. To give you an idea, the current doubling time of human population is something like 60 years. That means, for example, that if we were to anticipate that we'd run out of meaningful room on Earth in 60 years' time, we'd have to start working on our "second home" now, to have it ready. Once it was ready, we'd have to be working on two more. Then four, and so on. Good luck with that!
(Note: After we have consumed the Earth and converted it to habitats, we will have to consume Jupiter in a similar way in about 500 years. This gets out of hand very quickly.)
EDIT: El-oh-el at the few people who's fee-fees were hurt enough by this back-of-the-envelope analysis of growth rates and resource use to downvote it. Keep fighting the good fight, no matter how lonely!
I also don't think humanity will last this long, but as an academic problem it's fun to think about.
Funny I would have expected that to happen when we started consuming more than the primary production of the planet: https://www.nationalobserver.com/2017/08/09/opinion/heres-ho...
We didn't.