You might have trouble getting strong Wi-Fi into your attic room but connecting the wider cosmos is on a whole different level – and one expert says it could take 300,000 years to hook up the whole of the Milky Way.

Instead of stretching cables from planet to planet we could flash light from our Sun out into the depths of space, just like signalling with a hand in front of a flashlight, suggests the new proposal.

Duncan Forgan, from the University of St Andrews in the UK, has done the maths behind a model that uses laser beams from Earth to interfere with the Sun's rays as our planet circles around it, beaming out messages beyond the Solar System.

If we could find 500 other technologically advanced civilisations in the Milky Way, then a communications system stretching the length and breadth of the galaxy would take around 300,000 years to build, says Forgan.

"If you want to communicate with someone on the other side of the galactic centre, there's lots of stuff in the way – dust, stars, a big black hole – so you can take the long way around using the network," Forgan told Leah Crane at New Scientist.

So even if we weren't in the right place to receive signals from one particular planet, we could still get the message via several other systems first.

By using planets as they circle around their stars we could put together a network with regular bursts of signals – and we already have telescopes like Kepler looking at planets passing in front of stars, so less work would be required on the receiving end.

And the idea solves the problem of power, because we'd be using stars as the basis of the network.

As for the laser pulses used to modulate the light of the Sun as it passes by Earth, the system was proposed last year by scientists from Columbia University – in fact it could be used to conceal our planet as well as send messages into deep space.

We should point out that the computer models that Forgan has put together are yet to appear in a peer-reviewed journal, so we'll have to wait for other experts to check the sums.

Forgan also admits some limitations to his work: it doesn't take into account shifting planetary orbits over time, and to achieve even these extremely long timelines it would probably need the participation of hundreds of alien civilisations to help us build up nodes in the network… if we can only find them out there to work with!

Even with those caveats, though, it suggests an interesting approach to space communication. But any construction work is still a long, long, long way off, so best to hang on to that text to Alpha Centauri for the time being – or leave it in your will for your descendants to deal with.

Other experts aren't convinced that the proposed system would work, especially with the need for help from other planets to set it up.

"Once a civilisation is advanced enough to have the technology to build megastructures, it's much more likely to leave its planet," Avi Loeb, from Harvard University, told New Scientist.

"Each signal would take thousands of years to travel back and forth. In cosmic time that may not be that long, but you need patience."

Considering the vast distances involved, it's kind of amazing that we ever get signals from the probes and rovers we've sent out into space. Researchers are hard at work on ways in which our interplanetary communications can be improved, and now there's a new model to factor in.

We can only hope the problem of email spam gets solved in the next 300 millennia.

You can read the research on the pre-print website