How heavy is information?

Most of us know that computers represent all types of information—e-mails, documents, video clips, Web pages, everything—as streams of binary digits, 1s and 0s. These digits are mathematical entities, but they are also tangible ones: They are embodied and manipulated as voltages in electronic circuits. Therefore, every bit of data must have some mass, albeit minuscule. This prompted DISCOVER to ask the question: How much would all the data sent through the Internet on an average day weigh?

In searching for an answer, we scanned technical databases, tore through reference books, Googled like crazy, and checked with experts. It soon became apparent that if we wanted an answer, we were going to have to work it out for ourselves, as no one else appears to have tackled this question before*. So we put our thinking caps on and set the coffee machine on extra strong.

The key to figuring out the weight of the Internet relies on understandi ng the essential process that controls all the information passing through it, whether you are talking about an e-mail being sent across the street or a video feed from a Webcam on the other side of the world. In order to travel across the Internet, information is broken down into packets—little gobbets of data ranging from a few dozen to over a thousand bytes in size. As well as the information being transmitted, the packet also contains addressing details that routers—computers dedicated to moving data around—use to determine where the packets should go.

No matter where a packet is sent or what type of equipment it happens to pass through, one basic cycle repeats over and over until it arrives at its destination: The message is stored in a computer’s memory, analyzed to see where it should go next, somehow for transmission (whether it be as electrons down an Ethernet cable or as photons radioed out from a Wi-Fi card), sent along to the next computer in the chain, decoded, and then stored in the memory of that computer. Repeat as often as necessary.

What’s important are not the individual electrons or radio waves that get transmitted from your computer but the pattern of bits they describe. The electrons or radio waves that are sent directly from your own computer usually don’t get far—a few hundred feet at most—before being digested by another computer. Even when you send packets as light pulses down fiber-optic cables thousands of miles long, repeaters buried every 20 miles or so on the seafloor absorb incoming photons and transmit new photons to the next repeater.

Nine percent of Internet traffic is due to e-mail. Seventy-five percent is due to file sharing.

In other words, the physical objects that move through the Internet never go very far. What really goes the distance—what carries the weight, for our purposes—is the bit pattern that represents each packet, which gets continually rebuilt in the electronic memory of system after system as information traverses the network. One way to understand it is to imagine that I have a car that I want you to have. You, oddly enough, live on an island that is completely unreachable by sea or air, so I can’t deliver my car by shipping it to you directly. Fortunately for us, your island happens to be equipped with a state-of-the-art workshop and a huge supply of car parts. So to send the car to you, I examine it in detail and write down a set of plans, which I fax to you. You then assemble the car from the plans. Presto! You have a new car to drive around your island, one that is definitely real and (here we go) that can be physically weighed.

If we can work out the weight of the bits associated with a piece of information when it is assembled in a computer’s memory, we are halfway to figuring out the weight of the Internet.