Lifeboat Foundation

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.

Still, even the mere appearance of the correspondence is more than suggestive. It’s telling that there is something deeply fundamental to the hologram, that the physics of the volume of the universe might just translate to the physics on the surface, and that there is more to be learned there.

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 1990s.

The AdS/CFT correspondence is not a solution to the problems posed by string theory per se, but a statement motivated by advances in the theory when one takes the holographic principle seriously. It is also not a revolution by itself, but it does tell us that we are not entirely misguided when we make the bold claim that we live in a hologram, and begin to dream about what that revelation might entail.

We need to, briefly I assure you, unpack these acronyms to see how powerful this connection is, and what it might teach us about the wider universe. The “AdS” stands for anti-de Sitter, which is a particular kind of solution to Einstein’s general theory of relativity. The name comes from Dutch physicist Willem de Sitter, who constructed a mock universe that was empty of all matter and energy with the exception of a strong outwards curvature.

Even though the guts of General Relativity are obtusely mathematical, and for decades was relegated to math departments rather than proper physics, you get to experience the technological gift of relativity every time you navigate to your favorite restaurant. GPS, the global positioning system, consists of a network of orbiting satellites constantly beaming out precise timing data. Your phone compares those signals to figure out where you are on the Earth. But there is a difference in spacetime between the surface of the Earth and the orbit of the satellites. Without taking general relativity into account, your navigation would simply be incorrect, and you’d be late for dinner.

As revolutions go, general relativity is a big one. And as unifications go, it’s a warning. To make this union happen Einstein had to radically, permanently alter not just our conceptions of gravity as a force acting through space and time, but our conceptions of space and time itself. It took no less than a complete overhaul of our entire philosophical understanding of the relation between space and time to bridge the gap.

Continue reading “Holograms Might Save Physics” »

A video released by a Chinese state broadcaster shows the use of Microsoft Hololens 2 to simulate maintenance on a warplane.

The Chinese military is reported to be utilizing mixed-reality goggles manufactured by Microsoft for equipment maintenance, as shown in a video released by a state broadcaster.

Continue reading “China’s Air Force simulates warplane maintenance with Microsoft headsets” »

Producing fake sound reflections that simulate the presence or absence of an object could allow the military to hide assets underwater.

A hologram plate simulates the presence of a three-dimensional object by reflecting the appropriate light waves. Now researchers have demonstrated an equivalent behavior with sound by precisely mimicking the acoustic pattern scattered from an object [1]. The technique could be useful in military efforts to hide or disguise underwater objects, or it may be useful in modifying the reflected sounds of objects so that they are easier to identify by people with impaired vision.

The sound waves reflected from an object can be used to reconstruct its position and shape, an idea routinely exploited in sonar and ultrasound imaging. In principle, using similar concepts, a cleverly produced pattern of scattered waves streaming out of a small region could signify that an object is present when it is not. Several recent attempts to realize such “acoustic cloning” have been unsuccessful because of limitations in recording the precise pattern of waves an object reflects, a necessary preliminary step.

Join Brian Greene and Juan Maldacena as they explore a wealth of developments connecting black holes, string theory, quantum gravity, quantum entanglement, wormholes, and the holographic principle.

This program is part of the Big Ideas Series, made possible with support from the John Templeton Foundation.

Continue reading “String Theory, Quantum Gravity and Black Holes (Or, Are We Holograms?)” »

Monika Schleier-Smith is testing the idea that space-time emerges, like a hologram, from quantum interactions by attempting to make it in the lab.

By Lyndie Chiou

Holograms provide a three-dimensional (3D) view of objects, offering a level of detail that two-dimensional (2D) images cannot match. Their realistic and immersive display of 3D objects makes holograms incredibly valuable across various sectors, including medical imaging, manufacturing, and virtual reality.

Traditional holography involves recording an object’s three-dimensional data and its interactions with light, a process that demands high computational power and the use of specialized cameras for capturing 3D images. This complexity has restricted the widespread adoption of holograms.

The number of Star Trek sci-fi technology that ultimately became real-life tech never ceases to amaze. The series inspired the development of touchscreens, communicators became mobile phones, PAADs became tablets, replicators became 3D printing, and now holodecks are becoming virtual and augmented realities (VRs and ARs). And while fully immersive environments like the holodeck still remain in the realm of sci-fi, a recent report from BBC on a hologram zoo indicates that the future isn’t so far-fetched when it comes to immersive holographic.

The holograms use a new depth technology that not only makes the animals seem big but makes them visible as 3D objects rather than suspended 2D images.

According to the report, the visitors of Australia’s Hologram Zoo, which opened earlier this year, can dodge stampeding elephants, peer into the gaping jaws of a hippopotamus, pet-friendly giraffes, and witness more than 50 lifelike displays from dinosaurs to gorillas—all crafted from concentrated beams of light.