SETI and Lasers
I don't know how strong they are, I'll ask him the next time.
And it's just for peripheral inter-action, not obviously interplanetary signaling.
However, we're still not sure how dimensions overlap and if time/space can fold back into itself allowing space travel through wormholes or whatever. Looking outside the box can be fascinating at times.
"Imagination is more important than knowledge"
Albert Einstein