We have assumed for decades that water is necessary for life so we have mostly concentrated on looking for exoplanets with such a signature. They need to be not too big nor not too small, be rocky, and lie within the "goldilocks" zone where liquid water can exist. So far we have very few candidates.
We also assume that a magnetic field as we have on Earth is essential for maintaining an atmosphere for such planets to be viable. See: Earth v Mars. They are ultra difficult to detect but we have now found one, unfortunately it is too near to its sun for liquid water to exist.
However, all these discoveries keep on going up so that one day we will be finding rocky planets with magnetic fields lying within their own "goldilocks" zones. Unfortunately they will be so far away that we will never get there, or will we?
An accidental discovery has found that a warp drive (Star Trek anyone?) can exist. We don't travel through spacetime, it travels round us.
https://www.youtube.com/watch?v=MtXOLkVrdmE
Fascinating stuff