Let’s begin with a disclaimer.
While some colleagues conjecture the existence of more than one Universe, today we will restrict ourselves and our imaginations to our own bubble of information: the sphere with a radius equal to the distance light has traveled since time began some 13.8 billion years ago. Factoring in the expansion of the Universe, our information bubble has a radius of about 46 billion light years. Other theoretical universes, with other laws of physics, reside outside our cosmic bubble and are thus beyond our power of scrutiny.
Here we might as well add another clarification to ground our discussion in the plausible: By life I mean any self-sustaining network of chemical reactions able to metabolize energy from the environment and reproduce, following the rules of Darwinian natural selection. So, no spiritual machines way more advanced than we are; no bizarre, star-dwelling intelligent clouds; and no wormhole-inhabiting swarms of nanobots endowed with some sort of collective self-awareness. Flying spaghetti monsters are fine. (See below.)
What the whole Universe shares
With that out of the way, now we can really start.
Perhaps the most striking result of modern science is our understanding that the same laws of physics and chemistry apply across the vastness of space and time. We are now able to look at stars and baby galaxies billions of light years away from us, and billions of years old. When we look at them and analyze their properties, we find that they have the same chemical elements (albeit in different ratios) and that they evolve according to the same dynamic laws our own sun follows. Physical and chemical laws are the same everywhere and everywhen. This allows for us earth-dwelling creatures to expand our inquiries across the whole universe.
