This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The word "vacuum" may conjure the image of empty space. Maybe you think of a region far outside the solar system without planets, debris, gas clouds or light.
According to quantum theory, however, a vacuum is never truly empty. Quantum mechanics extends the Heisenberg uncertainty principle—which states that we cannot measure the position and the velocity of an object exactly at the same time—to a vacuum. The result is that a vacuum can never be still.
Instead of an empty space, we can imagine the vacuum as a dynamic object, with regular fluctuations in energy. Physicists at the University of Cambridge in the United Kingdom recently presented preliminary research showing direct imaging of these fluctuations in a lab-made quantum vacuum. Physicists have "seen" the quantum vacuum many times before, however.
And we can all see the effects of the quantum vacuum on atoms in the atmosphere—through the gorgeous light displays of the aurora borealis. The energy fluctuations of the quantum vacuum also create conditions for black holes to shrink. And modern cosmologists believe they played a role in the creation of galaxies, their impact felt in the earliest moments of our universe.
The idea of a "quantum vacuum" that isn't truly empty is more than an academic interpretation of equations. The most striking feature of the vacuum is the way it impacts the structure and dynamics of real objects. For instance, there is an ongoing effort geared toward observing the quantum vacuum directly in an experiment using high-intensity laser beams.
The strong electric fields from the laser pulses interact with the particles fluctuating in and out of the vacuum and, as a result, experience an effect called "birefringence." The birefringent vacuum treats light of different polarizations differently, similar to how polarizing sunglasses preferentially block light from specific glare-producing sources. This complex and interesting experiment will test the predictions of quantum mechanics on the structure of the vacuum through direct observation. This will not be the first time scientists have "seen" the quantum vacuum at work.
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