The first laser: 66 years of the light that changed the world

Every time I scan a product at the supermarket checkout, whenever I put a CD on, whenever the broadband reaches my flat over fibre — there's a beam of light behind all of it. And there's a specific date that explains why: 16 May 1960. Exactly 66 years ago, a physicist named Theodore Maiman pointed a ruby crystal at a xenon lamp and, for the first time in history, light did as it was told.

The man who kept going when everyone said no

In 1958, physicists Charles Townes and Arthur Schawlow published a theoretical paper in Physical Review describing how it might be possible to create a coherent light amplifier — what would come to be called the laser, short for Light Amplification by Stimulated Emission of Radiation. The paper started a race. Laboratories around the world tried to be the first to build the device in practice.

Theodore Maiman worked at Hughes Research Laboratories in Malibu, California. When he proposed using a synthetic ruby crystal as the active medium, the reception was sceptical. The reference calculations of the day indicated ruby would be far too inefficient — the fluorescence wouldn't be enough to sustain amplification. Maiman went back over the calculations and found that the accepted numbers were wrong. Ruby's quantum efficiency was considerably higher than the literature assumed.

With a budget of $50,000 — a fraction of what rival labs were spending — Maiman assembled a simple device: a synthetic ruby cylinder with silver-coated ends, wrapped in a helical xenon flash lamp. When the lamp fired, it delivered enough energy to excite the ruby's atoms. The emitted photons bounced between the mirrored ends, stimulating a cascade of emission. The result came out of the partially reflective end as a pulse of coherent red light — every photon at the same frequency, in the same phase, in the same direction.

On 16 May 1960, the system worked. Maiman was 32.

Why "coherent light" matters so much

Ordinary light — from an incandescent bulb, from the sun, from a candle — is chaos. Photons of varying wavelengths, in different phases, scattering in every direction. Useful for illuminating, useless for precision.

Coherent light is something else. When every photon vibrates in sync, at the same frequency and in the same phase, the beam holds its shape over long distances and can be focused on a tiny point with concentrated energy. It's the difference between a watering can and a needle.

That characteristic is what makes the laser useful in radically different contexts: you need the same coherence to cut steel in a factory and to read the pits on a 90s pop CD.

"A solution looking for a problem" — and the solutions that turned up

When Maiman presented the laser to the world at a press conference in New York in July 1960, the newspapers described the device as a "death ray" — a nod to the science fiction novels of the era. What nobody knew was that the laser would be something far more mundane and, at the same time, far more transformative: a precision tool that would fit into almost every sector of human activity.

Maiman himself liked to quote the line that circulated among researchers at the time: the laser was "a solution looking for a problem". It took less than a year for the first problem to appear.

In 1961, Charles Campbell used a ruby laser in retinal surgery. It was the device's first medical use — and ophthalmology would be transformed for good. Decades later came LASIK, capable of correcting short-sightedness by burning corneal tissue with micrometre precision. Today, millions of people see without glasses because of the laser.

The invisible lasers in your daily life

You probably use a laser dozens of times a day without thinking about it:

• Barcode scanner: that red light at the supermarket checkout is a low-power laser reading the stripes of the barcode.
• CDs and DVDs: your drive's reader uses a laser to detect the pits and lands burned into the disc. It was the laser that made the digital audio era viable, and then optical storage in general.
• Fibre optics: high-speed internet works by transmitting laser pulses through glass filaments. Each beam can carry billions of bits per second. No laser, no broadband.
• Laser printers: the beam draws the image onto an electrostatic drum which then transfers toner to the paper. Faster and more precise than inkjet for large volumes.
• Robotic surgery: micrometre cuts, minimal scarring, faster recovery. The laser scalpel goes well beyond ophthalmology — oncology, cardiology, dermatology.

66 years on: a light that doesn't go out

UNESCO declared 16 May the International Day of Light, in direct tribute to Maiman's experiment. It's one of the few commemorative dates that celebrates neither a person nor a country, but a physical principle — the stimulated emission of radiation that Einstein described theoretically in 1917 and that took another four decades to demonstrate in practice.

Theodore Maiman died in 2007, at 79, without ever receiving the Nobel Prize — an omission the scientific community has never stopped questioning. Townes, who formulated the theory, won the Nobel in 1964. Maiman, who made it work, was left out.

But the absence of a prize doesn't erase the fact: in 66 years, no technology has burrowed deeper into everyday human life than the laser. It's in hospitals, in factories, in datacentres, in supermarkets, in tattoo studios, in cinemas, in telescopes and in the dusty CD players in the corner of the room. It all started with a ruby crystal, $50,000 and a 32-year-old physicist who refused to accept that everyone else's calculations were right.

If you enjoy these milestones in the history of computing and physics, it's worth reading the post on Claude Shannon — the man who invented the bit, whose information theory is the mathematical foundation of the digital era the laser helped build. Got a laser-related memory that stuck with you — a scratched CD, a surgery, a light show? Tell us in the comments.