Magnetic hard drives will not be replaced by SSDs for the long foreseeable future.
The capacity/$ will never be competitive for SSDs.
This is an industry consensus, and one that I agree upon (and I'm in charge of the SSD line at my company).
SSDs have their place in high performance systems, hard drives have their place in high capacity systems.
While this idea HRD is interesting, it will be a number of years before even a workable solution comes out.
electrical signals move at the speed of electricity. optical signals
move at the speed of light.
electric fields propogate at the speed of light.
...
Oh and for the record electricity moves really slow take the following from wiki as an example:
wikipedia said:
As a numerical example,for a copper wire of 1 square mm area, carrying a current of 3 amperes, the drift velocity of electrons would be about 0.00028 metres per second (or just about an hour to travel one metre).
Careful now, the drift velocity of electrons is not equal to the "speed of electricity"...
Electric field propogates at the speed of light (through the wire almost instantaneously)
Without getting into the electron physics, just imagine the wire is a pipe filled with water..
The electric field corollary would be water pressure.
Turn on the light switch (open the water valve), and the electrons start flowing almost immediately through the entire pipe (the water pressure pushes the standing water out the end of the pipe pre-filled with water almost immediately).
So here's a thought question:
If the drift velocity of electrons is 1m/hour, why doesn't it take 4 hours to turn on the light bulb from your light switch?
Answer?
Because the wire isn't empty- the copper atoms are already "filled with electrons", just like a filled water pipe.