# Holometer: Holographic Noise

This summer I am working at Fermi National Accelerator Laboratory as a Teacher Research Associate as part of the TRAC program. I plan on writing a series of posts about my experiences and, specifically, about the experiment with which I’m involved: the holometer. Before describing my specific contributions to the experiment, I think I should start with the theory that led to holometer experiment. One of my goals this summer is to be able to explain this experiment and the theory that it is testing in a way that can be understood by my students. This will take several revisions and this post is my first draft.

The theorist involved with this experiment is Craig Hogan and the holometer is designed to test the the holographic principle. What is the holographic principle? Some describe this theory as claiming that the reality that we perceive is actually a three-dimensional projection from the two-dimensional reality at the edge of the universe. While that sounds cool and sci-fi, I have no idea what it means.

An analogy that I think helps explain the holographic principle is that of graphics on a computer screen. When you play Angry Birds, the bird flies across the screen in an apparently smooth path:

However, if you zoom in and look more closely, you’ll see that the bird cannot follow an arbitrarily smooth path since the screen is made of pixels. As the bird flies across the screen, it must move in discrete intervals horizontally and vertically. That is, its location on the screen is quantized. What appears to be smooth movement, is actually the bird jumping from one pixel to the next. The minimum distance the bird can move is the width of one pixel. A pixel’s width is sufficiently small that we don’t notice these jumps as we play the game.

How does this analogy apply to the holographic principle? Space-time is the screen; we are the Angry Birds; and the Planck length is the width of a pixel. To elaborate, as we move through space-time, our movement is not perfectly smooth but, rather, jumpy because the smallest distance we can move is the Planck length (1.6 x 10-35 m)1. Similarly to how, if we zoom in on the computer screen, we can observe the jumpiness of the Angry Bird, through an analogous magnification we should be able to observe the jumpiness, or jitter, of our movement through space-time. This jitter is the focus of Hogan’s research and is called holographic noise. The holometer experiment is designed to measure this phenomenon. How can we build an apparatus that can measure this holographic noise when the Planck length is so incredibly small? Stay tuned for the next post in this series!

Does this make any sense? Feedback is most welcome!

This post is one in a series about The Holometer experiment and my work at Fermilab in the Summer of 2011:

1 The Planck length was derived from fundamental physical constants (speed of light, gravitational constant, and Planck constant) by Max Planck.

## 6 thoughts on “Holometer: Holographic Noise”

1. John Burk

Geoff, This is a great postâ€”the connection to AB is an excellent one, and I remember when I took a course on computer graphs, how hard it was to draw a straight line across a grid of pixels. I’m looking forward to the rest of your posts and especially curious to know who the holometer can measure plank level jitters.

2. Erwin van den Heuvel

To my understanding the holographic principles states that the amount of information That can be stored in a part of space time is Proportional to the area of that piece of space time And not to its volume. What it means is indeed quite unclear but to my opinion it’s not well explained By just quantizing space in planck pixels. Recent results, I believe, indicate that if space is indeed quantised It’s much finer grained than the planck length.