Positivity in the Sky

I will discuss the subtle interplay between the behaviour of gravity as we observe it in our “everyday experiments”, and its embedding within an ultimate high energy completion. In particular, I will emphasize how the notion of causality is manifested with gravity, a consideration which is particularly relevant for putting constraints on the physical theories we use to describe observations and make future predictions. By considering low-energy processes including effects from Standard Model particles, I will also argue how we can get an insight on some properties of physics at high energy, well beyond what is accessible with current and future observations and experiments.