> That assumption is based on my knowledge of physics

based on your knowledge of known physics. We're still adding to the periodic table...

>We're still adding to the periodic table...

That doesn't violate known physics in any way.

Very true, but the point is it just shows there's a lot we don't know still that an advanced civilization might and likely have already discovered and learned to harness/control.

>based on your knowledge of known physics.

Right, and for exactly that reason, it enjoys the advantage over competing theories.

We're not still adding to the periodic table. https://en.wikipedia.org/wiki/Oganesson , 118, was synthesized in 2002, and confirmed in 2015 and I don't think anybody is actively working on making https://en.wikipedia.org/wiki/Ununennium or https://en.wikipedia.org/wiki/Unbinilium for lack of resources right now.

If somebody is aware of groups actively working to synthesize above 119 please let me know.

Why is it difficult? You just point and shoot. Will take a long time but you will get there in the end.

First you need an incredible amount of energy to get even a modest mass out of the earth's gravity well. Then you you need a truly fantastic amount of energy to get it up to a fraction of the speed of light. Then you need an equally fantastic amount of energy to slow it down again at it's destination. Then you run into time dilation effects, which diminish the usefulness to the sender of any information they are going to get back (due to the delay).

My point was that you don't need to go fast if you have plenty of time. You just need to get out of gravity which we can do.

Going slowly has it's own issues. If it takes you 100,000 years to cross the space between 2 stars, you are going to need a lot of energy/food to keep your crew/robots/computers going - because there isn't going to be much solar energy available. Also is any civilization going to invest the effort to create a probe/mission that they are not going to hear back from over that sort of time-scale?

I thought that way 3 or 4 years ago. PBS Spacetime has quite a few great videos about that. (Videos by actual physicists and astrologers.)