Around the World in 8.5 megabytes

It all started with a friend of mine bragging about his internet connection.browser-98386_640

Apparently he runs at 360 Mbps, which means that one bit is being transmitted for the duration of 1/360th of a microsecond.

On the other hand, light travels in fibre optics at 200 m / microsecond.

That’s all we need to know to calculate the length of a bit, ie: how much of the cable a single bit occupies if we freeze time and examine the beginning and end of the signal that represents the bit. Its width is propagation velocity times signal duration.

So it is 200/360 = 0.56 m. A bit is about as wide as one of the chairs below:


This is far from what I’ve expected. I thought bits were tiny. A few mm at most. I was visualizing them as tiny little spots traveling through the wire extremely fast.

Now that I’ve done the math, I find it fascinating because I’m developing a new appreciation of the speed of light.

Everyone has some intuition about how fast a megabyte travels. Now imagine some 8 millions of the above chairs traveling from Brazil to Japan, as fast as a selfie does, and you get a taste of the speed of light. Well 2/3rds of it, but you get the idea…


Now the only thing remaining is to somehow develop intuition about what a “million” means, which I’m not going to say I possess. Nevertheless, I’m still tempted to do some calculations:

 Olympic size swimming pool  11 bytes
 The Great Wall of China  4.6 kilobytes
Circumference of the Earth 8.5 megabytes
Distance to the Sun 31 gigabytes



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