Kenji back in the 1940s and 50s the sound barrier was simply difficult to break in an airplane with our technology, we had already had many things that broke the barrier such as bullets and whips. However, the most important thing is that the sound barrier was not a mathematically proven barrier. The light barrier is. That is why it is impossible to move some thing faster than the speed of light. Also the speed of light has everything to do with time, we have flown jets around the world with atomic clocks showing that, because they were moving faster than the clock on the ground time for the plane slowed down (this difference was less then millisecond mind you). Also the universal measurment of time: planck time is in part defined by the speed of light.

 

If you want math here it is:

plack time = sqrt( (G * h) / c^5) 

  c= speed of light, h = dirac's constant, G = gravitational constant

 Time dilation = t' = t / sqrt( 1 - (v^2 / c^2))

t' = time for outside observer, t = time for you, v = velocity, c = speed of light

as you can see as v gets closer to c, the number for t' get larger meaning that while time for you may be progressing normally everthing you see around you is happening faster.