The Millisecond Signals From the Edge of the Universe

2026-07-09 · Signals & Sounds · 9 min read

In 2007, an astronomer sat down with data that was already six years old and found a scream buried inside it. Duncan Lorimer, at West Virginia University, had handed a student named David Narkevic a set of archived recordings from the Parkes radio telescope in Australia, observations made back in 2001 while the great dish swept the sky near the Small Magellanic Cloud. Somewhere in that pile of numbers was a single spike: a burst of radio energy lasting less than five milliseconds, so bright it briefly outshone almost everything else in the sky, and then gone. It had happened once, on 24 July 2001, and never repeated. Nobody had noticed it for years.

That spike, now known as the Lorimer Burst, was the first fast radio burst, or FRB, and it carried a strange fingerprint that would define the entire field. Radio waves of different frequencies do not travel through the universe at exactly the same pace. When a sharp pulse crosses the thin plasma of interstellar and intergalactic space, its higher frequencies arrive slightly ahead of its lower ones, smeared out into a downward sweep. The amount of that smearing is called the dispersion measure, and it works like an odometer for distance: the more space the signal has crossed, the more electrons it has passed through, and the more its frequencies are spread apart. The Lorimer Burst's dispersion measure was enormous, around ten times more than everything in our own galaxy could account for along that line of sight. If the number meant what it appeared to mean, the burst had come from far outside the Milky Way, from something perhaps billions of light-years away, releasing in a few thousandths of a second as much energy as the Sun pours out in days.

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