Its negativity like this that holds us back.
In reality, your sentiment is correct. Sure, there are laws of physics. But they are also unknown, as the ones humans understand don't describe all observed phenomena by a long shot. There are still restrictions even so, but incredible unknowns await us. As they always have.
What engineering-minded folks frequently don't understand is the need to apply sheer old willpower, after using all that intellect. Ending with a positive, with the notion that it can be done; we just have to figure out how.
Though, thankfully for humanity - not "everybody"!
I mean, what have we come to, when a European will go and take a risk, for a chance at an awesome discovery, and an American dare not? ;)
The explorers who first went sailed into the deep Atlantic, with unknown seas and lands beyond, were full of doubts too -- but they did it anyway. Because they had to. In our time, we humans have to continually rekindle our explorer spirit, no matter how settled or distraught our ambient culture becomes. We must explore, with optimism and willpower -- and yes, with plenty of intellect and skepticism too, but end with optimism -- precisely in order to solve the actual problems our world faces.