"This finding had practical applications for telegraph communications. For
example, Heaviside actually solved one of the biggest problems affecting
long distance telegraph and telephone communication in 1887 -distortion. It
was known that different frequencies travel with different speeds on a long
cable. For example, the low bass frequencies in a voice signal travel faster
than the high treble frequencies. When the cable is long enough, the
frequencies smear, and both voice and telegraph signals become garbled
noise. Heaviside used his equations to show that if inductances (i.e., a
small coil of wire) were added along the length of the cable, the distortion
could be reduced." From:
http://www.ieeeghn.org/wiki/index.php/Oliver_Heaviside

" It was known that different frequencies travel with different speeds on a
long cable".

Is the same in air and space?
S*