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.

>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.