A ten thousand year trip that requires many generations, some form of stasis, biologically ageless people, and/or non-biological people, etc, is at least conceivable within the scope of our current knowledge of how the universe works.
Faster than light travel is not.
Far more reasonable to work within the bounds we know than assume completely inconceivable advances will allow us to ignore those boundaries.
The speed of sound isn't a fundamental physical constant and breaking the sound barrier was never against the laws of physics. Many things in nature exceed the speed of sound, and humans have had tools/objects that could exceed the speed of sound for several thousand years.
Nothing travels faster than the speed of light. No known natural phenomena, nothing we have ever made. Indeed, we cannot even conceive of how the speed of light might be exceeded without using similarly impossible things.
The whole reason the halo drive is interesting is because there isn't anything about it that requires reality to be redefined.
