Might it be unwise to deliberately aim radio signals out into deep space, not knowing who or what is out there

Stephen Hawking has previously suggested that it might be dangerous to do so.

They will probably rofl. 

It is hard to grasp how BIG space is. Here is an example to give you an idea just how far apart things are.

The distance from earth to sun is called an astronomical unit, AU. It happens that the number of AU in a light year is nearly equal to the number of inches in a mile. Imagine the earth to be one inch away from the sun. At this scale the sun is less than one hundredth inch wide, just a speck of dust. The entire solar system would fit within a man's outstretched arms. The nearest star is another speck of dust FOUR MILES away. 

So if you sent a signal, at light speed, it would take four years to reach the nearest star. If there were anybody there to pick it up, and they could travel at light speed, it would be four years more for them to visit. 

When you consider the loss of power from a spreading signal, it only makes sense to beam your signal. So you can only beam to one star system at a time. And the NEAREST one is eight years to get an answer, and no indication that anybody is there to answer.

So which way do you want to point your signal?

probably

Unwise but only as a pointless waste of time, effort and energy.

Whilst obviously we cannot safely assume no other society at least as advanced as ours (in science at any rate) exists elsewhere within our own galaxy, and might possibly be able to pick up and analyse an artificial radio signal extra-terrestrial to them; it would be so far away that any signal we could transmit would take many years to arrive, and then arrive there too weak to detect and analyse sensibly.  

Our largest radio and optical telescopes can resolve galaxies and detect r.f. sources in them at immense distances, but only because the signals they emit naturally are many orders of magnitude more powerful than anything we could possibly generate artificially.