Holographic Universe: Fermilab to Probe Smallest Space-Time Scales

Conceptual design of the Fermilab holometer (Fermilab)
Conceptual design of the Fermilab holometer (Fermilab)

During the hunt for the predicted ripples in space-time — known as gravitational waves — physicists stumbled across a rather puzzling phenomenon. Last year, I reported about the findings of scientists using the GEO600 experiment in Germany. Although the hi-tech piece of kit hadn’t turned up evidence for the gravitational waves it was seeking, it did turn up a lot of noise.

Before we can understand what this “noise” is, we need to understand how equipment designed to look for the space-time ripples caused by collisions between black holes and supernova explosions.

Gravitational wave detectors are incredibly sensitive to the tiniest change in distance. For example, the GEO600 experiment can detect a fluctuation of an atomic radius over a distance from the Earth to the Sun. This is achieved by firing a laser down a 600 meter long tube where it is split, reflected and directed into an interferometer. The interferometer can detect the tiny phase shifts in the two beams of light predicted to occur should a gravitational wave pass through our local volume of space. This wave is theorized to slightly change the distance between physical objects. Should GEO600 detect a phase change, it could be indicative of a slight change in distance, thus the passage of a gravitational wave.

While looking out for a gravitational wave signal, scientists at GEO600 noticed something bizarre. There was inexplicable static in the results they were gathering. After canceling out all artificial sources of the noise, they called in the help of Fermilab’s Craig Hogan to see if his expertise of the quantum world help shed light on this anomalous noise. His response was as baffling as it was mind-blowing. “It looks like GEO600 is being buffeted by the microscopic quantum convulsions of space-time,” Hogan said.

Come again?

The signal being detected by GEO600 isn’t a noise source that’s been overlooked, Hogan believes GEO600 is seeing quantum fluctuations in the fabric of space-time itself. This is where things start to get a little freaky.

According to Einstein’s view on the universe, space-time should be smooth and continuous. However, this view may need to be modified as space-time may be composed of quantum “points” if Hogan’s theory is correct. At its finest scale, we should be able to probe down the “Planck length” which measures 10-35 meters. But the GEO600 experiment detected noise at scales of less than 10-15 meters.

As it turns out, Hogan thinks that noise at these scales are caused by a holographic projection from the horizon of our universe. A good analogy is to think about how an image becomes more and more blurry or pixelated the more you zoom in on it. The projection starts off at Planck scale lengths at the Universe’s event horizon, but its projection becomes blurry in our local space-time. This hypothesis comes out of black hole research where the information that falls into a black hole is “encoded” in the black hole’s event horizon. For the holographic universe to hold true, information must be encoded in the outermost reaches of the Universe and it is projected into our 3 dimensional world.

But how can this hypothesis be tested? We need to boost the resolution of a gravitational wave detector-type of kit. Enter the “Holometer.”

Currently under construction in Fermilab, the Holometer (meaning holographic interferometer) will delve deep into this quantum realm at smaller scales than the GEO600 experiment. If Hogan’s idea is correct, the Holometer should detect this quantum noise in the fabric of space-time, throwing our whole perception of the Universe into a spin.

For more on this intriguing experiment, read the Symmety Magazine article “Hogan’s holometer: Testing the hypothesis of a holographic universe.”

Say Hello To My Little Friend: The Atom, Imaged

atom_photo

I am fascinated with outer space, this is true. But if you stop to think about it, the inner space between the atoms is just as awe-inspiring as the vast distances separating the planets, stars and galaxies. In actuality the volume inside an hydrogen atom is essentially empty; the single electron “orbits” (if we consider the simple Bohr model of the atom) the central proton at a huge distance. It’s analogous to a quantum star system, where a planet orbits its parent star, hundreds of millions of miles away.

However, atoms aren’t as simple as Niels Bohr’s famous model (although Bohr’s model is none-the-less important as it always has been). The electrons occupy a cloud, rather than specific orbits, and the electron’s position cannot be defined as a point, more a statistically defined volume. As dictated by quantum theory these clouds vibrate at certain frequencies, depending on the electron energy. These electron energies are analogous to the simple electron “shells” physicists refer to in the textbooks; each progressively higher shell occupying a higher energy state. In reality, in the slightly fuzzy quantum world, the frequency of electron oscillation increases with energy.

Examples of electron atomic and molecular orbitals. The "lobes" are representative of the electron clouds surrounding the nuclei
Examples of electron atomic and molecular orbitals. The lobes are representative of the electron clouds surrounding the nuclei (source)

When I was in university, I loved seeing the different modes of electron energy in 3D visualizations of the atom (pictured right). Lobes of electron clouds vibrating at different energies seemed to make sense. But now, for the first time, the clearest photographs of a single atom have been taken, with lobes of electron clouds — as predicted by quantum theory — intact.

This research soon to be published in the journal Physical Review B, demonstrates detailed images of a single carbon atom’s electron cloud (pictured top). Taken by Ukrainian researchers at the Kharkov Institute for Physics and Technology in Kharkov, Ukraine, these images clearly show the electron cloud in two energy states.

This amazing feat was accomplished using a field-emission electron microscope. Although this microscope has aided physicists since the 1930’s to image the vanishingly small, the Ukrainian researchers have developed a new way of making the tool so sensitive, single atoms can be imaged. After arranging a ridged chain of carbon atoms (only tens of atoms long) inside a vacuum chamber, the researchers passed 425 volts through the atoms. At the tip of the chain, the end carbon atom emitted its electrons and a surrounding phosphor screen captured an image. This image was of the electron cloud surrounding the single carbon atom.

Up until this point, field emitting microscopes have only been able to resolve the arrangement of atoms in a sample. This is the first time physicists have been able to see the structure of an electron cloud around an atom.

It’s always nice to validate a bedrock physics theory with photographic evidence, it’s exciting to think what the Kharkov Institute scientists will do next…

Source: Insidescience.org