eli5: What really happens under the hood when we get to video chat in real time to someone that is on other side of world?

Question

I’m wondering how is this information actually transferred, how it can be that fast that we can see without any latency at all.

Thanks in advance,

In: 20

Answer 1

There is a delay, just often not very observable because of just how fast the signals travel. Some of the delay is actually just processing the information, and some of it is actual physical travel time.

Information travels mostly through fibre optics, which the signal travels around 60% the speed of light in. So in this case it’s literally a fluctuating light beam with a particular pattern that routers on both ends understand. It’s like Morse code but it’s not Morse code. There are actually massive fibre optic cables that connect continents.

It can travel through cell towers like to and from your phone network, which has a microwave transmitter that sends signals to other towers that have a receiving dish. It’s important here to note that microwave radiation is a form of light, all radiation is, this travels at like 99.999% the speed of light in air. Your phone also has a small transmitter and receiver and can relay that information to the nearest cell tower. It doesn’t need to be powerful because the cell tower is powerful.

It can travel to space satellites, like if you had starlink internet for example. Where it will relay from one satellite to the next, and then back down to the ground. This is also around the speed of light, maybe marginally faster sometimes because of low atmosphere for some of the journey.

In all cases it’s sending the information about each pixel for a frame as some 0’s and 1’s.

Pure red is the message 11111000 00000000 for example.

But since screens have many millions of pixels, to reduce the amount of information it will average several chunks of pixels together, and only send information on which pixels have changed, which is sometimes why your video quality reduces in favour of being fast.

Now it is doing the same thing for the audio at the same time, sending information about the audio channels in a sequence, many times a second.