For the first time, a team led by researchers at MIT LIGO Laboratory has measured the effects of quantum fluctuations on objects at the human scale.

In a paper published in Nature, the researchers report observing that quantum fluctuations, tiny as they may be, can nonetheless “kick” an object as large as the 40kg mirrors of the US National Science Foundation’s Laser Interferometer Gravitational-wave Observatory (LIGO), causing them to move by a tiny degree, which the team was able to measure.

The universe, as seen through the lens of quantum mechanics, is a noisy, crackling space where particles blink constantly in and out of existence, creating a background of quantum noise whose effects are normally far too subtle to detect in everyday objects.

It turns out the quantum noise in LIGO’s detectors is enough to move the large mirrors by 10-20 meters — a displacement that was predicted by quantum mechanics for an object of this size, but that had never before been measured.

“A hydrogen atom is 10-10 meters, so this displacement of the mirrors is to a hydrogen atom what a hydrogen atom is to us — and we measured that,” says Lee McCuller, a research scientist at MIT’s Kavli Institute for Astrophysics and Space Research.

The researchers used a special instrument that they designed, called a quantum squeezer, to “manipulate the detector’s quantum noise and reduce its kicks to the mirrors, in a way that could ultimately improve LIGO’s sensitivity in detecting gravitational waves,” explains Haocun Yu, a physics graduate student at MIT.

“What’s special about this experiment is we’ve seen quantum effects on something as large as a human,” says Nergis Mavalvala, the Marble Professor and associate head of the physics department at MIT. “We too, every nanosecond of our existence, are being kicked around, buffeted by these quantum fluctuations.

“It’s just that the jitter of our existence, our thermal energy, is too large for these quantum vacuum fluctuations to affect our motion measurably.

“With LIGO’s mirrors, we’ve done all this work to isolate them from thermally driven motion and other forces, so that they are now still enough to be kicked around by quantum fluctuations and this spooky popcorn of the universe.”

Yu, Mavalvala, and McCuller are co-authors of the new paper, along with graduate student Maggie Tse and Principal Research Scientist Lisa Barsotti at MIT, along with other members of the LIGO Scientific Collaboration.

LIGO is designed to detect gravitational waves arriving at the Earth from cataclysmic sources millions to billions of light years away.

The research was funded, in part, by the National Science Foundation.