How is it "physically impossible?" Every time some leftwing open-borders douche bag makes a claim about the wall, it turns out he just pulled it out his ass.
We understand you want to destroy this country, so who do you think you're fooling?
It's all ready been explained why it's impossible.
As an example, the golden gate bridge.
It takes a whole year just to paint it by the time the crews finish one end .
They have to start the other end again.
No imagine a border wall 30'high running 2000 miles . By the time work crews fixed a breach in CA there would be 10 more any were from Arizona to Louisiana.
The maintenance costs would kill any imagined value the wall would have as a barrier.