I am seriously sceptical of the concepts presented in your first posts' article, FBS.
Ok, so people thought the sound barrier couldnt be breached ... they were all proved wrong .... but this is (approx.) 300,000 km per second we're talking about here.
So they give some explanation that theyll be hitching rides on stars -- but how close is the closest star (apart from the sun) .. hmm few light years??? and i doubt the sun's gravitational field will be strong enough, let alone the let the craft close enough, thats massive heat we're talking about here.... 30,000 or so celcius? .

Also, The fastest humans have gone so far is Mach 21 on reentry to earth in the space shuttle ... speed of light?!? thats ridiculous ....

... and I see no way they are going to blow up 30 billion tonnes of TNT to propel their craft... unless they get the Middle East involved