Thought that hadn't occurred to me before; light must have an upper limit in terms of bandwidth, because a square wave consisting of the presence or absence of a photon would form a basic 'photon-bit' of information - and there are only so many photons you can send in a given time while still maintaining a square wave. Obviously this relates to the wavelength of light used,
The shorter wavelengths of light are therefore 'higher bandwidth' ie, gamma rays, as you can send more in a given time period, which leads to two thoughts;
1) This would fit with the
Kardashev Scale that defines civilisations by their energy use (type 1,2,3)
2) Can we therefore expect that civilisations will use increasingly higher energy wavelengths for communication as the demands of bandwidth increase and their access to greater energy resources enables low cost / high energy / high bandwidth communications?
Yes i realise that the bandwidth we're talking about is stupidly high, but who knows what data demands there will be in future? Maybe they'll invent teleportation and need to send the precise location of every particle in a person's body before they can 'beam you up'.
Interesting to think about, anyway...
Markus