This is the fundamental question behind the Fermi paradox, which in essence states that we should see some evidence for extraterrestrial life, given the large number of stars in the observable universe (70 sextillion, woo!).
So I am going to flip the question around, and assume some possible scenario where an alien civilization might rise up out of the galactic muck and see our universe as its own plaything.
- Assumption #1: There is or will be a supremely advanced species. This civilization should do any of the following: spontaneously generate matter and energy, is immortal, and can perceive and travel through space, across dimensions, and even between universes.
- Assumption #2: Time travel is possible and has been mastered by the species in Assumption #1.
- Assumption #3: The species in Assumption #1 is aggressive. Not necessarily in the sense of being destructive or bloodthirsty, but willing to expand to fill other niches, like every form of life on Earth.
If it's the former, then why are we still here? If a hostile alien race that has existed for many lifetimes of other universes can time travel, then it can surely jump to when we were defenseless single-celled organisms and destroy all life on Earth for the entire existence of this universe. Or perhaps they can foresee that we are not and never will be a threat, either because we mushroom cloud ourselves, or some natural disaster like a comet destroys all life on Earth, or at least all sentient life.
Let's look at the other option: the most advanced species in the entire history of all universes is us (or at least, an evolved version of us.) I find that rather difficult to believe. Not only are there untold numbers of stars and planets in our observable universe that are older than our sun and Earth, but we are just scratching the surface with our predictions for other possible universes, which could be nearing an infinite number that may have existed for near an infinite amount of time. The likelihood that we are or will be the most advanced species ever is pretty slim.
For sake of optimism, let's reject that we (or some other species on our planet) will blow ourselves up, and that we will not be able to foresee and avert possible natural disasters. Let's also assume the anthropic bias that lets us be the center of the known universe is also incorrect.
So therefore, if both options are unlikely (either aggressive aliens or us), I think that at least one of my three assumptions is invalid. So either:
- Counter-Assumption #1: There will never be a supremely advanced species.
- Counter-Assumption #2: Time travel is never possible.
- Counter-Assumption #3: The advanced species in Assumption #1 is not aggressive.
Also, the very idea that time travel is not possible is pretty silly, especially considering the idea that monkeys barely out of the jungle have theorized that space and time are perpendicular sides of the same coin.
So let's look at #3. Why are species on our planet aggressive? Why are they genetically programmed to reproduce, and fill an ecological niche at the expense of another species? Why do tigers have fangs and claws, rose bushes have thorns, and people kill each other in all sorts of creative ways?
Easy. Scarcity. Life on our planet evolved with limited resources. Every species on this rock fights tooth and nail for every scrap of food, which most likely is some other species that we happened to tooth and nail to death. We are bounded by our evolutionary heritage to kill or be killed, and either dominate our environment or have our environment dominate us.
However, what if the advanced civilization in Assumption #1 has already fixed their problem with limited resources? What if they have solved all hunger, have no need of land, can generate any sort of matter or energy at will, and have tinkered with their own genetic code to limit their own exponential population growth?
What if they are no longer aggressive, either because their evolutionary track was not as cutthroat as ours, or because their technology solved the problem of scarcity ages ago, and thus no longer need to dominate the universe, let alone us?
Notice, that I'm not saying that the species in Assumption #1 is benevolent. I don't imagine they would be particularly thrilled to have competition, at least not from us if we cannot conquer our version of scarcity. Though perhaps they would at least be interested to see our evolution from single celled organism to universe traveling civilization, if we can control our unchecked aggression first so we don't annihilate ourselves in the process.
So if there is an advanced civilization, and we want to meet them someday, then I suggest that the number one priority for our civilization--besides not blowing ourselves to smithereens--is to master our control of available resources without exceeding it, and figure out a way to transition ourselves from an aggressive dominating civilization to a non-aggressive, non-dominating one.