A recent post by the BBC regarding AI Data Centres What’s the big deal about AI data centres? by Michael Dempsey Technology Reporter, asks the following important question:

Why is proximity so important?
Every metre of distance between two chips adds a nanosecond, one billionth of a second, to the processing time.

Really?

The definition of the speed of light is: 299,792,458 metres per second.

So light can travel 0.299792458 metres in 1 nanosecond.
A rough multiplication shows that it takes approximately 3 nanoseconds for light to travel 1 metre.

Information cannot be conveyed at a speed faster than that of light.

On first principles then, the article is incorrect.
I could go on regarding inter-chip comms, but won’t.

Footnote. I investigated into making a comment on the article to the BBC, but was faced with spending time giving details, that I considered were not important, and I simply gave up. No, they didn’t ask what colour toilet paper I use..