The empty void is not silent.
While space is devoid of air, and without question no one can hear you scream, the cosmos is not nearly as silent as you might think. Every inch of space is full of light – radiation, visible light, and radio. All of these are example of the same basic ‘thing’: an electromagnetic wave. The only difference amongst all of these is the wavelength of the light. Within a specific range, our eyes detect light as visible. What we think of as dangerous radiation has shorter wavelengths than the visible range, radio waves longer.
As light travels over the extreme distances of space wavelengths stretch. What started as visible light over time will degrade into heat, then into microwave, then eventually into radio waves. And the more distant the signal, the further back in time it originated because of the speed of light limits. There are stars and galaxies whose light we can detect as radio signals, though the earth’s atmosphere interferes with this detection. So we sent a temporary satellite called ARCADE – a weather balloon with a sensor package – to listen at the far edges of our atmosphere to get around the interference. We intended ARCADE to listen to events as far back to the Big Bang as possible with current technology.
ARCADE detected a radio signal in the depths of space. Not unexpected as the mission was to detect and listen to radio galaxies. What was unexpected was the strength and universal direction of the radio signal we picked up. A ‘hiss’ – a noise signal – overwhelming any other signals in that time frame at a volume six times that of any other previously detected radio galaxy. In order to create a signal of this strength and blanket the past with it you would have to place each radio galaxy end to end and still not come close to the strength of the signal. As the head of the ARCADE team, Dr Alan Kogurt, put it: “The energy alone that could generate this level of signal is incomprehensible.”
After studying the signal, replicating the detection, and eliminating other known radio sources we have been able to come to only one conclusion:
In 2006 we discovered the universe was screaming at us.
Threat level: Existential