[bojan]

Hmmmm

I fully understand all the aspects of positive thinking expressed in this thread..
However, we have to be realistic in terms of restrictions the physics laws impose.
If you need GW transmitter to relay the message from star to star with decent data transfer rate, I can't see it being packed in the volume of couple of grams...
Of course, all functionality required for control module of such device is already packed in much smaller volume... there is no dispute here.

The problem is required SNR (Signal to Noise Ratio) for the reliable (and fast) communication link.
The probe travelling at 20% light speed will pass through Solar system in 24 hours max. It has to send the accumulated information back (otherwise, what is the point of such exercise?).

The real-time data rate used with communication with Voyager probes is 160b/sec, the current distance of V1 is 134.16AU
Alpha Centauri system is 300000AU away, further away by factor of 2236.
If the Voyager were there, the signal from it would have been 5,000,000 times weaker.
That means, to have the same data rate (lousy 160bps, 20B/s)), the transmitter power must be that many times more powerful.. which is around 100MW (23*5e6).
And those numbers will remain the same in the future, they are independent on technology development.