How do we know that what we’re seeing in the world around us is real and not merely an illusion? To apply the analogy that writers from The Register used (link), imagine characters on a television show could talk to us – their surroundings would seem like a real 3D world to them, when really it is a 2D image projected onto the television screen. Therefore there has been a theory established known as the Holographic Principle, which states that the space around us is a 2D structure “painted” on the cosmological horizon. We use cosmological horizons to set the scale and size of the observable universe.
Up until now, the principle has remained as just a theory. However, this week physicists at the Fermi National Accelerator Laboratory near Chicago, Illinois, have started collecting data via an instrument called a Holometer. The data obtained could give us more insight into whether the theory has any truth to it. Craig Hogan from the University of Chicago says, “The theory is that space is made of waves instead of points, that everything is a little jittery, and never sits still”. The Holometer is designed to calculate the strength of this ‘jitter’ and observe the quantum behaviour of the waves. “We want to find out whether space-time is a quantum system just like matter is,” said Hogan. “If we see something, it will completely change ideas about space we’ve used for thousands of years.”
The Holometer functions via two perpendicular interferometers, each of which involves a powerful laser beam being shot a beam splitter through a 40 meter tube. The beam splitter will split each beam in two. Each beam is then reflected back to the splitter using mirrors and when the beams meet at the right angle, visible fluctuations will be generated in the light if the ‘jitter’ in space-time exists.
Telling background noise apart from holographic waves could cause some problems. However, Aaron Chou, part of the team involved in the experiment says, “If we find a noise we can’t get rid of, we might be detecting something fundamental about nature – a noise that is intrinsic to space-time. It’s an exciting moment for physics. A positive result will open a whole new avenue of questioning about how space works”.
The Holometer is estimated to take around a year to collect enough data to analyse. Hopefully the instrument will provide some interesting new paths to explore in quantum physics.
The image below shows an invidual Michelson interferometer and how it works.
A brilliant article by New Scientist on this theory and the Holometer can be viewed [here]. Happy reading!