Most of us have seen holographic images – if not up close in a laboratory or a museum of science, then in movies and TV shows. The illusion of a three-dimensional image created by a process using two-dimensional data is an impressive technological feat, and it’s not hard to imagine amazing holographic applications becoming generally available in the not very distant future.

 

In recent years, some intrepid astrophysicists have applied the “Holographic Principle” to the study of the Universe, and their theories present the possibility of a hologram whose scale is truly cosmic. Could it be that the Universe and everything in it is, in reality, an accumulation of 2-D information projected into 3-D space from the largest data disk imaginable – a disk whose edges extend to the farthest reaches of space?

 

Whoa! Let’s take a few steps back.

What is the Holographic Principle?

The concept of a holographic Universe comes from a “mathematical quirk” of string theory.  Briefly, quantum field theory, of which string theory is a part, works better in a two-dimensional Universe without gravity than it does in the three-dimensional, observable world of general relativity in which we reside.

The holographic principle states that gravity derives from thin, vibrating strings that are all holograms of a flat 2-D surface.  Within the holographic Universe, 3-D space is the image of a 2-D Universe projected across a massive cosmic horizon. In this theoretical framework, the Universe would appear to us just as we experience it, in all its apparent 3-D glory, with space, time, and gravity.

If the holographic principle applies to flat space, it might look like this. (Image credit: Wikimedia via Motherboard.Vice.com)

Arising from quantum mechanics, the holographic principle was first postulated as a response to Stephen Hawking’s “information paradox,” which states that black holes seem to “swallow” information. According to quantum theory (not to mention the First Law of Thermodynamics), this is impossible. A holographic interpretation is the reply of quantum mechanics to Hawking’s conundrum.

A (Very) Brief History of Quantum Physics

In the 1970s, Hawking introduced theories proposing that Einstein’s general theory of relativity, so useful to our understanding of the Universe, was potentially incomplete or even flawed.

Specifically, Hawking suggested that at certain very extreme boundaries, physics, as we understand it, starts to fall apart. His example of black holes seems to defy the established principle that matter can’t ever be lost. But if that’s so, what happens to the matter and energy that is pulled in?

“Einstein’s theory of general relativity explains almost everything large scale in the universe very well, but starts to unravel when examining its origins and mechanisms at quantum level.”

— Kostas Skenderis, professor of mathematical sciences, University of Southampton

That question remains unanswered for now. However, as quantum physics began to develop, and more scientists turned their thinking to such problems, various theories started to be developed to overcome the limitations of general relativity. These include string theory, the idea of multiverses, and other mind-bending possibilities.

Gravity—A Cosmological Constant (Headache)

A persistent problem in post-Hawking cosmology is gravity. Gravity is a force that is hard to square with the existence of dark matter and black holes, or with extreme situations such as the first, infinitesimally brief microseconds of the Big Bang.

As observed by Planck, the CMB is a snapshot of the oldest light in our Universe, imprinted on the sky when the Universe was just 380,000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars and galaxies of today. (Image credit: ESA and the Planck Collaboration)

Because of the problems gravity created, it became expedient to remove it from the definition of the Cosmos in certain mathematical equations attempting to describe the Universe. This had two immediate advantages: first, it eliminated gravity as a problem to resolve; and second, it reduced the Universe to a flat, two-dimensional plane.

Skimming the Surface

Now, a group of scientists from the U.K., Canada, and Italy has undertaken tests to see whether cosmic microwave background (CMB) radiation (residual traces from the very early phases of the Big Bang) can be accurately understood using two separate theories: the standard model of ultra-rapid expansion and inflation, which is consistent with general relativity; and the new quantum holographic universe model. The results of this work were published in Physical Review Letters in January 2017.

Using observations of the CMB captured by the Planck satellite to document patterns of energy fluctuation in the radiation, the scientific team observed that both models (standard and holographic) were virtually equivalent in predicting the same fluctuation patterns. That is to say, neither model can be excluded from consideration.

Artist’s impression of the Planck spacecraft. (Image credit: ESA/AOES Medialab)

The “virtual” element in the results indicates the need for further experimentation, which means that both the holographic model and Einstein’s standard model are still in play. More detailed observation of the CMB may yield a better understanding of the shape – flat or fully rounded – of the Universe.

Toward Understanding the Mystery of “Quantum Gravity”

So far, research into the quantum structure of the Cosmos has required the exclusion of gravity as a factor. So, the next major goal for ongoing study is to find a way to meld the general relativity model, including not only gravity but time as well, with quantum theory. This new field for investigation is termed “quantum gravity.”

“Holography is like a Rosetta Stone, translating between known theories of quantum fields without gravity and the uncharted territory of quantum gravity.”

—Niayesh Afshordi, associate professor of astrophysics and gravitation, University of Waterloo

In this new field, “quantum gravity” would theoretically cohere with quantum mechanics and not negate general relativity. While this is an important step toward a proof that we could be living in a holographic universe, it would not be the proof in and of itself. It might take another Einstein or Hawking to guide us into this strange, flat “Holographiverse.”