Who lives in optical fibers under the sea?
Let’s talk about the internet. I initially understood it to be a complex system of connected devices that I use every day without thinking about it much further. But how are the devices connected, and how do they actually communicate? What actually is the internet?
Before we dive too deep, let’s look at data and how it’s transmitted. All data can be broken down into bytes. A byte is composed of 8 bits, and each bit will takes the form of either 0 or 1. A packet is a collection of bytes which we will estimate to be around 1,000 bytes per packet for this blog. Packets are the building blocks of data transmission for all of the internet.
Now think about the sheer amount of information that is transmitted through the internet continuously. Let’s say you want to send an email to one of your professors. We can estimate 80 words of text in an email to take up about 10,000 bytes, which we can consider to be roughly 10 packets.
Now say you’re a multi-tasking fiend, and at the same time you compose your email, you want to look at pictures of cute puppies. The Google home page, as of October 2019, takes up 66.9 kilobytes, so rounding up we’ll say that it takes 70 packets to load. On top of that, say that you are like me, and take every waking opportunity you can get to listen to music. So at the same time, you’re on Spotify streaming one of your favorite playlists. That will take up roughly 2.4 megabytes or 2,400,000 packets per minute. That’s not even counting the 5 to 35 tabs that you may have open at any one time. And all of this is just on one device, not considering your phone, your iPad, or any other device you use to access the internet. Think of this expanded to the roughly 51,000 students that attend the University of Illinois at Urbana-Champaign. That’s a LOT of packets of data continuously streaming.
This fine mess of information is dealt with through a series of rules of transmission, called Internet Protocols. Each device is assigned an IP address that serves as identification for that device, similar to the address of your house. The computer, or phone, or whatever device you are using to read this blog has an IP address that is unique, and allows for connections to be made. Websites also have IP addresses that the Domain Name Server (DNS) will retrieve when you type the website domain name into the search bar on your browser.
What if you want to go back to Google and visit the puppies again? The packets that make up your request to access Google will be broken up and tagged with information that tell each packet where to go, and in what order it should be reassembled once it reaches its destination. Packets can travel out of order, and through multiple paths, and finally reassembled in the correct order at the receiving end. This breakup of data allows for information to be distributed much faster and more efficiently than if it were stuck with just one option for path of travel.
After the data is broken up, the packets are sent to wonderful devices called routers. They direct the little packets of data to their next hop in their journey through the internet. In addition to breaking, packets take many hops from network to network along their path. Here’s the series of paths it took for the packets to go from the computer where I typed this blog to YouTube. (You can ignore the masterful rainbow I made in MS Paint to cover up an IP address.) You can find the number of network hops between you and any website you want by pulling up your Command prompt and typing in “tracert” followed by the webpage you want to get to.
Eventually, after many hops between networks, the packets will reach a server in a data center where the IP address for that specific page lives, and data transmission of that webpage back to you begins.
So how does that webpage physically get back to you? In an attempt to summarize, binary bits of data that compose our packets can be communicated through the media of light, electricity, and radio waves. From the data center, the binary information is transmitted through optical fiber cables, in the forms of light generated by semiconductor devices. Due to our friend, total internal reflection, light can be completely reflected within the optical fiber, bounce along the length, and transmit information. Because the light can be refracted at multiple angles, multiple signals can be passed along the same optical fiber, and multiple signals can be sent at once. The optical fiber can span long distances, even under the sea, with the help of amplifiers. This allows for cross continental internet communication.
That data will be transduced into electrical signals at your local router or a cellular tower. In either case, since most of our connections are wireless, once the signal becomes electric, it is transduced again into electromagnetic waves through antenna with electrons moving through small copper wires. The receiving conductive surface in your device will transduce the electromagnetic waves into electric impulses that we can interpret as binary, which is what all data transmission is broken down into.
Phew. There is much more to learn about each of these components; I barely scratched the surface in this blog, but I hope this gave you a bit of insight into the incredibly nuanced global computing network we get to interact with every day.