You all know what this little number did back in October 1947 with then-Captain Charles Yeager at the controls.

Barriers, especially sound barriers, were made to be broken.

Now, back in the day, the sound barrier really was thought of as a barrier - you don't go faster because your plane would become really difficult to control as you approached the speed of sound due largely to the effects of compressibility: your (often unpowered) control surfaces would become really difficult to operate and as how the planes of the era only ever reliably approached Mach 1 while in a dive, odds are you'd have a few seconds to contemplate how crappy this situation was before you got intimately familiar with the ground.

Thanks to better engines, a better grasp of aerodynamics, and better aircraft construction techniques it was eventually demonstrated that man can into supersonic flight. Thanks to our ever growing body of knowledge since then, we've only been accelerating.