[mystified5016]

We laid transatlantic telegraph wires before we even had a hint of the physics involved. It create the entire field of transmission and signal theory.

Shannon had to invent new physics to explain why the cables didn't work as expected.

[pas]

I think that's misleading.

There was a lot of physics already known, importance of insulation and cross-section, signal attenuation was also known.

The future Lord Kelvin conducted experiments. The two scientific advisors had a conflict. And the "CEO" went with the cheaper option.

""" Thomson believed that Whitehouse's measurements were flawed and that underground and underwater cables were not fully comparable. Thomson believed that a larger cable was needed to mitigate the retardation problem. In mid-1857, on his own initiative, he examined samples of copper core of allegedly identical specification and found variations in resistance up to a factor of two. But cable manufacture was already underway, and Whitehouse supported use of a thinner cable, so Field went with the cheaper option. """

[anthk]

THe telegraph it's older than radio. Think about it.

[cft]

that was 1854. You basically only needed Ohm's law for that, which was discovered in 1827

[JPLeRouzic]

Ohm's law for a cable 4000 km/3000 miles long? That implies transmission was instantaneous and without any alteration in shape.

I guess the rise time was tens of milliseconds and rebounds in signals lasted for milliseconds or more. Hardly something you can neglect.

For reference, in my time (the 1980) in the telecom industry, we had to regenerate digital signals every 2km.

[cft]

"Initially messages were sent by an operator using Morse code. The reception was very bad on the 1858 cable, and it took two minutes to transmit just one character (a single letter or a single number), a rate of about 0.1 words per minute."

https://en.m.wikipedia.org/wiki/Transatlantic_telegraph_cabl...

I guess your bandwidth in 1980 was a bit higher.