Aliens - The Fermi Paradox - Where Are All The Aliens?

There are many possible answers to the Fermi Paradox not mentioned, here are some of my favorite answers.
1. We haven't been looking long enough. The Universe is unimaginably large, and we have only been searching for a few decades. The signals we have made would have only made it to the closest 300 stars at most, with about 50 being close enough to signal back, assuming the signal survives long enough. it's been said (I forget by who) that we've search so little of the sky that assuming there is no life because we have not found any yet, is like scooping out a teaspoon out of the ocean, and then assuming there are no whales in all the oceans. Personally my favorite hypothesis.
2. Perhaps advanced alien civilizations do not look like what we think they do. We assume any space faring alien race would use Alcubierre drives, Wormholes and harness light energy and blacks holes for power, all of which would be easily detected. Maybe a step in technological advancement would be harnessing Dark Energy, Tachyons, or a particle we do not know how exists. There is a lot about the universe we don't know, and maybe the aliens are aware of a trick we do not know.
3. Related, maybe all our SciFi assumptions about Wormholes, Warp Drives and faster than light-travel is just fantasy, and it really is impossible to exceed light speed, making meaningful communication between civilizations impossible and making us effectively alone. Depressing, but possible.

Either universe might be WAY bigger than we comprehend or the concept of FTL travel is truly impossible.