The quantum world is weird - just when scientists think they've figured out something, a new thing comes in. One classic example is the long-held and popular theory of empty space is being challenged because of recent discoveries suggesting that empty space is not empty at all.
For a long time, physics have defined nothingness as space where matter does not exist in the "lowest possible energy state." According to Heisenberg's uncertainty principle, however, there is a limitation of how much we can know about quantum particles. That's because all the things in quantum mechanics are both a particle and a wave. Furthermore, even if you know its position, you will never be able to predict its momentum and vice versa.
That brings up the idea that the reason for its unpredictability is because that nothingness or vacuum is really filled with a potpourri of particles that appear, disappear, and reappear randomly and that flurry of action creates the fluctuating energy field.
The problem with Heisenberg's theory is that he could not provide evidence about the existence of that fluctuating energy. I the 1940s, a team of scientists found indirect evidence of this energy field but the real breakthrough came in 2015 when German physicist Alfred Leitenstorfer and his team announced that they found direct evidence for the fluctuating energy field. What they did was use a super-short laser pulse which they fired into the vacuum. The process caused some small changes in the polarization of light. But again, they could not specifically identify what causes these energy fluctuations.
In 2017, Leitenstorfer and his team made another breakthrough. Using the same process, they created what they call 'squeezed light,' a state where light is in slow-motion in a certain segment of space and time. That light in slow motion acts like a slow car on a highway which created a traffic jam. Because of that 'traffic jam,' the scientists were able to detect where these fluctuations are coming from. What more, they were able to discover that these fluctuations dropped to the lowest possible energy.
Just like new discoveries, the team said that further experiments and verifications are needed to really establish it as a fact.
