@BillRM,
Most ALL of the criticism on the "nanochip" has nothing to do with any cientific possibilities.
1Moores Law haw mqde it posibl for a nanoized spaceship
2the 100 GIGAWATT laser poses no energy transfer problems to the sail as designed
3 We routinely accelerate molecules to sub light speeds in seconds.
The real problems as posted in several physics blogs
1. money for the laser array(approx, 1 km square)(estimated at 2 TRILLION penyenzies)
2. Trust - that such an array wont become a weapon for satellite destruction
3. location of the laser array (politics and atmospherics dissipating the energy)
4Mr Milner has a spotty record(Hes already funded the "Breakthrough LISTEN" project for wide scan detection of EM spectral signals from possible alien sources