Paul M. Sutter, Author at Universe Today

December 21, 2023December 18, 2023 by Paul M. Sutter

Why the Universe Might be a Hologram

The colored circle represents the hologram, out of which the knotted optical vortex emerges. Credit: University of Bristol

A quarter century ago, physicist Juan Maldacena proposed the AdS/CFT correspondence, an intriguing holographic connection between gravity in a three-dimensional universe and quantum physics on the universe’s two-dimensional boundary. This correspondence is at this stage, even a quarter century after Maldacena’s discovery, just a conjecture. A statement about the nature of the universe that seems to be true, but one that has not yet been proven to actually reflect the reality that we live in. And what’s more, it only has limited utility and application to the real universe.

December 20, 2023December 21, 2023 by Paul M. Sutter

The Strangest Coincidence in Physics: The AdS/CFT Correspondence

The west limb of the Sun imaged by NuSTAR and SDO shows areas of high-energy x-rays above particularly active regions (NASA/JPL-Caltech/GSFC)

Attempts to turn string theory into a workable theory of nature have led to the potential conclusion that our universe is a hologram: that what we perceive as three spatial dimensions is actually composed of only two. The greatest realization of this hologram-led program is a proposal that goes by the awkward and clunky name of the AdS/CFT correspondence, first proposed by string theorist Juan Maldacena in the late 1990’s.

December 19, 2023December 21, 2023 by Paul M. Sutter

Why String Theory Requires Extra Dimensions

String theory found its origins in an attempt to understand the nascent experiments revealing the strong nuclear force. Eventually another theory, one based on particles called quarks and force carriers called gluons, would supplant it, but in the deep mathematical bones of the young string theory physicists would find curious structures, half-glimpsed ghosts, that would point to something more. Something deeper.

December 18, 2023December 18, 2023 by Paul M. Sutter

The Holographic Secret of Black Holes

This artist’s impression depicts a rapidly spinning supermassive black hole surrounded by an accretion disc. This thin disc of rotating material consists of the leftovers of a Sun-like star which was ripped apart by the tidal forces of the black hole. Shocks in the colliding debris as well as heat generated in accretion led to a burst of light, resembling a supernova explosion. Credit: ESO, ESA/Hubble, M. Kornmesser

As weird as it might sound, black holes appear to be holograms.

November 15, 2023November 9, 2023 by Paul M. Sutter

How Black Holes Consume Entropy

Artist view of orbiting black holes. Credit: Caltech/R. Hurt (IPAC)

Entropy is one of those fearsomely deep concepts that form the core of entire fields of physics (in this case, thermodynamics) that is unfortunately so mathematical that it’s difficult to explain in plain language. But we will give it a try. Whenever I see the word entropy, I like to replace it with the phrase “counting the number of ways that I can rearrange a scenario while leaving it largely the same.” That’s a bit of a mouthful, I agree, and so entropy will have to do.

November 15, 2023November 9, 2023 by Paul M. Sutter

The Origins of the Black Hole Information Paradox

Artist's impression of an ultramassive black hole (UBH). Credit: ESA/Hubble/DSS/Nick Risinger/N. Bartmann

While physics tells us that information can neither be created nor destroyed (if information could be created or destroyed, then the entire raison d’etre of physics, that is to predict future events or identify the causes of existing situations, would be impossible), it does not demand that the information be accessible. For decades physicists assumed that the information that fell into a black hole is still there, still existing, just locked away from view.

November 14, 2023November 9, 2023 by Paul M. Sutter

The Maddening Simplicity of Black Holes

Black holes.

The name is said to come from the Black Hole of Calcutta, an infamous prison that you cannot escape from. It is a fitting name, for black holes are the ultimate cosmological prison.

November 13, 2023November 9, 2023 by Paul M. Sutter

Why Even Einstein Couldn’t Unite Physics

Einstein Lecturing — Albert Einstein during a lecture in Vienna in 1921. Credit: National Library of Austria/F Schmutzer/Public Domain

Near the end of his life Einstein worked tirelessly to find a way to unite electromagnetism with gravity. He could not, and never did, the notes scattered on his desk scrawled with fruitless probes and useless hypotheticals. Indeed, Einstein passed without even understanding why the two forces could not be united.

November 12, 2023November 9, 2023 by Paul M. Sutter

How Einstein Unlocked the Quantum Universe and Created the Photon

This all-sky Fermi view includes only sources with energies greater than 10 GeV. From some of these sources, Fermi's LAT detects only one gamma-ray photon every four months. Brighter colors indicate brighter gamma-ray sources. Credit: NASA/DOE/Fermi LAT Collaboration

It started with a simple experiment that was all the rage in the early 20^th century. And as is usually the case, simple experiments often go on to change the world, leading Einstein himself to open the revolutionary door to the quantum world.

November 11, 2023November 9, 2023 by Paul M. Sutter

How to Think About a Four-Dimensional Universe

Hubble image of SDSSJ0146-0929, a galaxy cluster that is massive enough to severely distort the spacetime around it. There's the mass of the visible stars and gas, but there's also a hidden amount of dark matter that adds to the cluster's mass. Credit: ESA/Hubble & NASA; Acknowledgment: Judy Schmidt

In Einstein’s famous theory of relativity the concepts of immutable space and time aren’t just put aside, they’re explicitly and emphatically rejected. Space and time are now woven into a coexisting fabric. That is to say, we truly live in a four-dimensional universe. Space and time alone cease to exist; only the union of those dimensions remains.