Over and out “Marconi’s first transmission is still out there, about 10% of the way to the closest visible star. Granted it is pretty attenuated by now>” Bob Lucky, technology consultant, formerly of Bell Labs and Telcordia * *EDN: Voice of the Electronics Engineer - May 12, 2005 - page 17
Radio signals travel at the speed of light. Astronomers use the “light-year” - the distance light will travel in one year - as a measure of distance. Marconi made the first radio transmission across the Atlantic on December 12, 1901. So Marconi’s first transmission would have covered a bit over 103 light-years by this time.
From the list of nearest stars we can see that the nearest visible star is about 4.36 light-years distant. You might note that 103 light-years is a lot more than 10% of the way to the nearest star :).
I do not know how many stars are within 103 light-years. Given the the list of 44 stars within 14.3 light-years we could (very roughly) estimate 16,400 stars within 103 light-years. So rather that 10% of the way to the first, instead Marconi’s first transmission has already passed something like 16,000 stars.