Do people regularly interrupt you in conversation? Does your online chatter require too many smileys? Is your pen pal letting you down? Maybe you want to try someone off-planet. Here's how to make the attempt.
Technically, a lot of what we do goes off into space. Any Earthside light that isn't blocked by clouds heads off through the universe. Blinking, say, the Vegas Strip off and on again to spell out, "Hi, There!" in Morse Code would be a financial, technical, and political challenge, but it would be possible. We also could send a message via space probe snail mail, like The Golden Record that launched with Voyager containing sounds and images from Earth. But maybe you want your own message out there. How would you do it?
What's the best medium for messages into space?
A golden plaque or record has a kind of aesthetic appeal to it, and letting there be light can make one feel nice and biblical, but the best way to transmit messages is using radio waves. Visible light is energetic, but it has a very short wavelength. That short wavelength can get scrambled as it goes out through space. Though the universe is most famous for being a horrible, soul-shattering void, it's also pretty dusty. Dust in space, or on the planet you're trying to reach, scatters short wavelengths. Longer wavelengths move through dust clouds without getting splattered all over the place and made unnoticeable.
If you want to try transmitting messages at higher ends of the spectrum, try broadcasting at the frequency 1420 megahertz. This is the frequency at which hydrogen vibrates. Not every society is going to have a base ten number system. Not every civilization is going to use certain frequencies for cell phones, and not every song will sound the same through a different atmosphere. But it's unlikely that whatever corner of the universe the signal ends up in will have a more basic atom than hydrogen. This is the way to get a civilization to notice you.
How powerful a transmitter is needed to beam a signal into space?
It really depends on how far you're willing to go, and it depends if they're listening. Radio is what cuts through space best, and radio isn't that popular these days. Some astronomers have speculated that, as we move from radio waves to fiber optics and internet connections, we might be currently 'going quiet' to alien astronomers. What's more, the radio waves we do send out are less powerful, because receivers are more accurate. As a planet, we're shutting up. But at least this means you'll have little competition.
You can start small. One of the earliest broadcasts meant to leave the earth happened during Project Diana. Some scientists wanted to see how far they could get their radio signals to go, so they got together a transmitter that "provided 3,000 watts at 111.5 MHz in 1/4 second pulses, and the antenna (a "bedspring" dipole array) provided 24 dB[decibels] of gain." They bounced the pulses off the moon, getting their signal back about two and a half seconds later. This was in 1946, and made with radar equipment from World War II. The more ambitious 1974 Arecibo Message, a binary code meant to convey information about the solar system, the human form, the double helix and the Arecibo Telescope that broadcast it was given a power of 1000 kilowatts.
How can I get noticed by aliens?
Aw, honey. I'm betting that if you're building a transmitter in your back yard, you're already being noticed - especially by everyone who is trying to listen to the radio around you. But honestly, the best way to be noticed is to just keep transmitting. The Arecibo Message was broadcast for about three minutes. The signals to the moon were only short blasts. There have been other calls made to likely planets, but what planet earth has mostly been doing is listening. And we haven't been hearing much.
One of the most celebrated bursts of sound was the famous Wow! signal. The Wow! signal was recorded at the Ohio State Big Ear Observatory in 1977. The universe provides plenty of background noise, so radio observatories 'listen' for loud sustained bursts of noise. One night, the computers recorded very loud, sustained noise that caused a volunteer to write 'Wow!' next to it on a print out. The noise went on for 37 seconds, which is the amount of time that the observatory took to look over a certain part of the sky. This was really something. And then it was gone. Although frequent attempts have been made to find such a burst again, none have been successful. If the Wow! message was from some other civilization, it may only have lasted a little while before being turned off. Don't make the same mistake! Just keep broadcasting, no matter what people tell you!
What should the broadcast be?
Sadly, a strong steady signals of 1420 megahertz may be the best chance of getting anyone's attention. Many human overtures to the great beyond have included pictures, words, and sounds. Nasa even once beamed out the Beatles song Across the Universe. No doubt aliens somewhere are criticizing them for their literalism. But unless you have a great plan and exact words that you need to convey, even if the beings receiving don't have a clue what you're saying, it's best to keep it simple.
You might be able to beam it out in pulses that have the beat of Queen's We Will Rock You, though.