Hydrogen · Science
Why 1420 MHz is a protected frequency
Under ITU footnote 5.340, all emissions are prohibited from 1400 to 1427 MHz. Why the world agreed to leave the hydrogen frequency in silence.
bairogonzalez.com team, drawing on Bairo's story · Published
The space around you is full of radio waves. At this very moment, signals from cell phones, Wi-Fi, FM radio, television, GPS and satellites are passing through your body. The radio spectrum is one of the most congested avenues humanity has ever built, and every band of it is fought over.
In the middle of that traffic, there is a narrow band where the world agreed not to speak.
The rule
The spectrum is divided by international agreement in the Radio Regulations of the International Telecommunication Union, the ITU, a United Nations agency. That's where it's decided who can use each piece of the airwaves.
The band from 1400 to 1427 MHz is reserved for passive services, which only listen: radio astronomy, Earth exploration by satellite and space research. And a short footnote applies to it, number 5.340, which says, in the original: "All emissions are prohibited in the following bands." The first on the list is 1 400–1 427 MHz.
In Brazil, Anatel follows the same allocation. Transmitting without authorization is a crime under article 183 of Law 9,472, of 1997.
Why right there
Because inside that band lies the hydrogen line, at 1420.405751768 MHz.
The signal arriving from the galaxy's hydrogen clouds is extremely faint. An ordinary cell phone, a few kilometers from a radio telescope, would emit with incomparably more power than an entire gas cloud thousands of light-years away. If anyone transmitted in that band, they would blot out the sky.
There's also an engineering reason. The hydrogen signal from distant galaxies arrives with its frequency slightly shifted, because of their motion and the expansion of the universe. That's why radio astronomy also observes below 1420 MHz, in bands that don't have the same total protection. The 27 protected MHz are the core, the place where silence is law.
Silence on the ground too
In some places, the care goes beyond the band. In the United States, since 1958, there has been the National Radio Quiet Zone, an area of about 33,000 square kilometers between Virginia and West Virginia, created to protect the Green Bank observatories. There, transmissions are restricted, and people's daily lives have adapted so the telescopes can listen.
Think about what that means. In the middle of the communication age, governments all over the world agreed to leave a piece of the spectrum untouched, not to make money, nor to win a war, but to keep listening to the universe.
Sources: ITU, Radio Regulations, footnote 5.340 · U.S. National Academies, radio astronomy spectrum · Law 9,472/1997, art. 183 · National Radio Quiet Zone
In Bairo's view
This is where the name Bairo gave 1420 MHz comes from: the frequency of silence. He reads this agreement as one of humanity's most beautiful gestures. In a world that talks nonstop, countries agreed to keep quiet in one place, so as to listen to what comes from far away.
For him, that silence is the place where one can find one's God. No one needs to share his faith to recognize the beauty of the image: the cleanest space in the spectrum is precisely the one no one may use for themselves.
And that's why, in his project, the number is only a symbol. No one transmits on 1420 MHz, not him, not 1420mhz. The 14:20 milestone and the record of the manifesto, told in Manifesto 14:20, are digital: written on the network, in tribute to the frequency, without touching it.
For you
Is there a protected band in your life?
An hour of the day, a corner of the house, a piece of the week where nothing gets in, no notifications, no bills, no noise, just so you can hear what's too faint to compete with everything else? Maybe that's where the idea you haven't heard yet lives, or the voice you trust.
It doesn't need to be much. Astronomers protect only 27 MHz in a spectrum of thousands. What matters is that the protection is taken seriously, every day, with no exception for the urgency of the moment.
The whole world made this agreement to listen to hydrogen. You can make a smaller one, with yourself, to listen to your own life.