I bet you know all this but 4 light years sounds near but 1 light year is 6, trillion miles, light travels at 186 thousand miles per second so it’s going to take over 4 thousand years for a rocket to arrive and 4 thousand years to come home.
The maths are insane because any civilisation may have died out long before we get there, we have to come up with new laws of Physics before we can travel anywhere.
That’s what professors of Quantum Physics work on and why they don’t rule out Aliens travelling the universe if they are millions of years in advance of us.
Radio / TV signals they have to point at the right star and people need to be listening
Just to be a little bit pedantic - we can't come up with laws of physics, they are true by definition and are discovered. A scientific law is a statement of observed phenomena. They aren't an attempt to explain the phenomena. What I think you mean (without wanting to presume) is that a lot of these laws start out appearing quite simple in easily observed nature, but our interpretation breaks down in certain extreme cases and so we can hone our understanding of laws over time.
What some physicists do is look for these extreme edge cases where our knowledge of laws no longer hold and in doing so they sometimes improve our understanding of the laws so that they can describe those edge cases.
In terms of travelling long distances, the laws of physics as you rightly say are prohibitive. You simply can't travel at lightspeed conventionally because the faster you go the more your relativistic mass increases and the amount of energy you need to go faster goes up exponentially. There's also time dilation, it's all very Flight of the Navigator.
An advanced civilisation could know much more about these extremes where the laws of physics as we know them break down. And so really there is no way of knowing how quickly they might be able to traverse space. For example, with enough mass, you can make space-time do some really funky stuff. Wormholes are one well-known theoretical example of this.
I have a passing interest in UFO stuff, just because I'm living for the day something interesting might happen to my life. I don't really believe in anything I've seen relating to UFOs/UAPs, including the OP, because none of it has ever met my standard of evidence, however it is a great source of entertainment for me. I stumbled upon this thread a few days ago about a "supposed whistleblower" on 4chan who is dying of cancer and so has spilled the beans online. It seems like obvious bollocks but I do commend him on how he has at least created an air of plausability.
Link here. Warning it is very very very long.