The primary source of energy for our planet is the sun. The sun gives us both light and heat. The fusion reaction inside the sun makes all life on Earth possible. On the other hand, it also prevents us to ever fly to the sun. The huge temperatures of more than 5700°C on the sun’s surface will destroy every space ship that we could build. But we still know a great deal about the sun, because with the energy that it sends us also comes a lot of information. The spectrum of the sun light tells us what chemical elements the sun is made of. Observing solar prominences with telescopes, we learn about the magnetic forces that are at work within the sun. Even though we cannot touch the sun, we learn about it through all the information it gives away with its energy.
In railway air brakes, the air pressure conveys both the energy to activate the brakes and the information about when to activate them. A tank inside each car stores pressurised air that it receives from the locomotive through the train line. The same line is also used to activate the brake. A drop in the air pressure in the line causes the brakes to activate. Because each wagon stores the energy from the line inside its tanks, there is enough energy for braking when the air pressure drops. This makes the system fail safe, because when the brake line is interrupted by an accident, the brakes will automatically activate themselves and the train comes to a stop.
Each radio system needs energy to send information via its antenna. This is true for every cell phone, laptop and also for deep space communication networks. As more and more devices use wireless communication, the space around is not only filled with the information that these devices send, but also with the energy that they use to do it. And we can use this energy to power other devices, like batteryless sensors.
The Power Grid
The power grid provides us with the energy to power our homes. Also, it provides information. Many home applicances use the frequency of the power grid as a stable clock base to show the current time. This fact is often overlooked, but recent events in Serbia and the Kosovo made it visible. A dispute over electric energy between both countries caused the frequency of the whole European energy grid to be a little lower than usual. The effect was that many clocks all over the continent lagged almost six minutes behind the correct time.
There is no information exchange without energy and vice versa. Many technical applications use this fact. When you design your next system, think about how to use it to your advantage, too.