Hologram Printer...

The new printer uses low-power continuous wave lasers to create holograms on a highly sensitive photomaterial developed by the researchers. Credit: C Yves GENTET

Topics: 3D Objects, 3D Printing, Applied Physics, Holograms, Optics, Research

Researchers have developed a new printer that produces digital 3-D holograms with an unprecedented level of detail and realistic color. The new printer could be used to make high-resolution color recreations of objects or scenes for museum displays, architectural models, fine art or advertisements that do not require glasses or special viewing aids.

"Our 15-year research project aimed to build a hologram printer with all the advantages of previous technologies while eliminating known drawbacks such as expensive lasers, slow printing speed, limited field of view and unsaturated colors," said research team leader Yves Gentet from Ultimate Holography in France. "We accomplished this by creating the CHIMERA printer, which uses low-cost commercial lasers and high-speed printing to produce holograms with high-quality color that spans a large dynamic range."

New printer creates extremely realistic colorful holograms, The Optical Society, Phys.org

Sonic Tractor Beam...

Sound image: the acoustophoretic display reproduces the logo of the University of Bristol. (Courtesy: A Marzo, B Drinkwater and colleagues)

Topics: Acoustic Physics, Holograms, Research, Star Trek

A midair visual display that uses a single acoustically-levitated particle has been unveiled by researchers in Spain and the UK. Dubbed an “acoustophoretic display”, the image is created by using two ultrasound transducer arrays to levitate the particle and manipulate it to trace out the desired graphic at high speed.

In 2015, Asier Marzo at the Public University of Navarra and Bruce Drinkwater at the University of Bristol created a sonic tractor beam that used ultrasound to levitate, rotate and move objects. Using a single grid of 64 off-the-shelf loudspeakers controlled by a programmable array of transducers the device created 3D fields of sound – acoustic holograms – that could hold and manipulate a small polystyrene particle in mid-air.

Since then, the field has progressed and earlier this year Marzo and Drinkwater revealed an acoustic levitation device that used two grids of speakers to hold and individually manipulate up to 25 polystyrene balls at the same time. This opened up the possibility of new applications for sonic tractor beams, including visual displays created with multiple levitated particles.

According to Marzo, such acoustic generated images, which he calls acoustophoretic displays, would offer an advantage over current holograms as they would not suffer from clipping. “[With holograms] the image can only be viewed from determinate angles and the frame of the display occludes the image, it is like looking inside a window,” he explains. “With the acoustophoretic displays the images reside in the physical space and can be observed without clipping from 360°.”

Ultrasound guides particle in a midair display, Michael Allen, Physics World

R2D2 Redo...

The image on the left shows the apparatus and the 3D image of a man. The trapping and illumination light emerges from the lens at the left of the man. The image on the right is a close-up of the 3D image of the man. (Courtesy: D E Smalley et al/Nature)

Topics: Holograms, Optical Physics, Science Fiction, Star Wars

A technique to create multi-coloured 3D images that can share space with physical objects has been developed by researchers in the US. The work is at an early stage, but it offers several potential advantages over currently available techniques for creating 3D images such as holography.

The technology used by the android R2D2 to project the 3D video footage of Princess Leia pleading "Help me, Obi-Wan Kenobi: you're my only hope" into thin air was never explained in the film Star Wars. Scientists, however, have invented several technologies capable of producing the impression of 3D images. The best known, and most widely used is holography, in which a 2D surface sends light to the eye in such a way that the brain reconstructs this light as having come from a 3D object. Unfortunately, this optical illusion only works for a fairly narrow range of viewing angles: "Holograms and displays like them are based on 2D modulating surfaces that have to be looked at like a TV screen," explains Daniel Smalley of Brigham Young University in Utah, "You always have to be looking into the screen to see it."

In a volumetric display, however, the light originates from where your eye sees the image. Such displays have several advantages over holograms. As the image does not rely on an optical illusion, for example, it is unaffected by the viewing angle. "You can be lying flat on the ground and you can see what's coming up out of the display," says Smalley. Furthermore, it is (at least in principle) possible to wrap the image around the viewer or another physical object.

Display creates 3D images that can be viewed from many angles, Tim Wogan, Physics World

Mirror, Mirror...

Leonard Nimoy (R.I.P.) as mirror universe Spock, "Mirror, Mirror," Star Trek, S2, E4

Topics: Holograms, Optical Physics, Quantum Mechanics, Star Trek 😎

When you look in the mirror, the image you see looks a lot like you—not exactly the same, because when you raise your right hand, your mirror-self raises its left. What’s more, the mirror image is merely an assemblage of reflected light, without a physical body behind it. Despite these differences, you can see an important connection between you and your reflection.

This type of mirror relation is a familiar and powerful form of symmetry. We can say that a Valentine heart is symmetrical because the left side is a reflection of the right. But the symmetry of your mirror image is different and deeper. A heart is symmetrical because the left and right side happen to have a similar shape. The symmetry between you and your reflection is due to the laws of physics. The nature of light requires your reflection to be symmetrical to you. It is an example of a powerful and subtle type of symmetry known as duality.

The duality between particles and waves is a central part of quantum theory. Light is clearly a wave: It has a wavelength that determines its color, and light waves can interact with each other to produce things like lasers. Light is also clearly a particle: It interacts with atoms as discrete photons; a single photon can be deflected like a billiard ball. Particle-wave duality means that quantum objects like light have a symmetry between their particle and wave aspects. They are particles with wave properties and waves with particle properties. They are both, and they are neither. The power of quantum theory is that you don’t need to distinguish between particles and waves. They are simply quantum objects with a duality between their particle and wave natures.

Does that mean that the universe is a hologram? Not quite. It means there is a duality...

Nautilus: What It Means to Live in a Holographic Cosmos
Brian Koberlein is an astrophysicist and physics professor at Rochester Institute of Technology.

3D Acoustic Holograms...

The researchers designed a hologram that projects sound waves with an amplitude pattern shaped like the letter "A". The top images show the simulated field patterns of the amplitude of sound waves at three representative depths. The bottom row shows the actual experimental amplitudes recorded in an anechoic chamber. (Courtesy: Scientific Reports 6 35437)

Topics: Acoustic Physics, Electromagnetism, Holograms, Metamaterials

Researchers in the US have created a printed array of metamaterials that can produce passive 3D acoustic holograms from a simple sound source, such as a single speaker. The device is made up of 3D-printed Lego-like blocks that can be put together in different configurations. The researchers say that their method is cheaper and simpler than other techniques and that they expect it to "open a new realm of holographic acoustic wave manipulation".

A visual hologram manipulates electromagnetic waves in the visible part of the spectrum to create a 3D image. Because sound also travels in waves, it should be possible to create complex 3D fields of sound – acoustic holograms – in a similar way. While visual holograms can be made with physical structures that diffract light, it isn't so easy with sound due to a lack of materials with the required acoustic properties. Generally, acoustic holograms use a transducer array controlled by complex phase shifting electronics.

Physics World: Building-block metamaterials shape 3D acoustic holograms
Michael Allen is a science writer based in Bristol, UK

Neutron Holography...

Interference pattern created by neutron holography.
Credit: NIST

Topics: Holograms, Neutrons, NIST, Research

For the first time, a team including scientists from the National Institute of Standards and Technology (NIST) have used neutron beams to create holograms of large solid objects, revealing details about their interiors in ways that ordinary laser light-based visual holograms cannot.

Holograms—flat images that change depending on the viewer’s perspective, giving the sense that they are three-dimensional objects—owe their striking capability to what’s called an interference pattern. All matter, such as neutrons and photons of light, has the ability to act like rippling waves with peaks and valleys. Like a water wave hitting a gap between the two rocks, a wave can split up and then re-combine to create information-rich interference patterns.

An optical hologram is made by shining a laser at an object. Instead of merely photographing the light reflected from the object, a hologram is formed by recording how the reflected laser light waves interfere with each other. The resulting patterns, based on the waves’ phase differences (link is external), or relative positions of their peaks and valleys, contain far more information about an object’s appearance than a simple photo does, though they don’t generally tell us much about its hidden interior.

Hidden interiors, however, are just what neutron scientists explore. Neutrons are great at penetrating metals and many other solid things, making neutron beams useful for scientists who create a new substance and want to investigate its properties. But neutrons have limitations, too. They aren’t very good for creating visual images; neutron experiment data is usually expressed as graphs that would look at home in a high school algebra textbook. And this data typically tells them about how a substance is made on average—fine if they want to know broadly about an object built from a bunch of repeating structures like a crystal (link is external), but not so good if they want to know the details about one specific bit of it.

But what if we could have the best of both worlds? The research team has found a way.

NIST:
Move Over, Lasers: Scientists Can Now Create Holograms from Neutrons, Too
Chad T. Boutin

On The Brane...

This challenges a holy grail of physics, and relates to The Standard Model; how we describe the four forces of nature and how they interact, even the Higgs Boson.

I almost hesitate to post it because many who do not "believe in the Big Bang Theory" will shout: aha! I say: ah, science - self-examining, exploring; learning more tomorrow than we thought we knew yesterday. Quantum mechanics had its trials and tribulations: Weins Law, Rayleigh-Jeans Law and the "ultraviolet catastrophe" eventually getting to Max Planck (of Planck's constant) and light seen as quanta. This eventually led to Einstein and the photoelectric effect in his Annus mirabilis papers generated in a lowly patent office in Munich. Thus we have the Internet, I-phones, flat screens, etc.

This description matches some of the wording I've seen over the years of the "universe as hologram" and admittedly either didn't understand or regarded as new age mystic pop culture. This challenge will have to be peer-reviewed and experiments performed to verify. Stay tuned...

However, Pluto is still not a planet.

A few nine-year-olds will send me hate mail now...

It could be time to bid the Big Bang bye-bye. Cosmologists have speculated that the Universe formed from the debris ejected when a four-dimensional star collapsed into a black hole — a scenario that would help to explain why the cosmos seems to be so uniform in all directions.

The standard Big Bang model tells us that the Universe exploded out of an infinitely dense point, or singularity. But nobody knows what would have triggered this outburst: the known laws of physics cannot tell us what happened at that moment.

“For all physicists know, dragons could have come flying out of the singularity,” says Niayesh Afshordi, an astrophysicist at the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

It is also difficult to explain how a violent Big Bang would have left behind a Universe that has an almost completely uniform temperature, because there does not seem to have been enough time since the birth of the cosmos for it to have reached temperature equilibrium.

In our Universe, a black hole is bounded by a spherical surface called an event horizon. Whereas in ordinary three-dimensional space it takes a two-dimensional object (a surface) to create a boundary inside a black hole, in the bulk universe the event horizon of a 4D black hole would be a 3D object — a shape called a hypersphere. When Afshordi’s team modelled the death of a 4D star, they found that the ejected material would form a 3D brane surrounding that 3D event horizon, and slowly expand.

The authors postulate that the 3D Universe we live in might be just such a brane — and that we detect the brane’s growth as cosmic expansion. “Astronomers measured that expansion and extrapolated back that the Universe must have begun with a Big Bang — but that is just a mirage,” says Afshordi.

Nature: Did a hyper-black hole spawn the Universe?
Physics arXiv: Out of the White Hole: A Holographic Origin for the Big Bang

The Matrix...

Nature

“Imagine waking up one day and realizing that you actually live inside a computer game,” says Mark Van Raamsdonk, describing what sounds like a pitch for a science-fiction film. But for Van Raamsdonk, a physicist at the University of British Columbia in Vancouver, Canada, this scenario is a way to think about reality. If it is true, he says, “everything around us — the whole three-dimensional physical world — is an illusion born from information encoded elsewhere, on a two-dimensional chip”. That would make our Universe, with its three spatial dimensions, a kind of hologram, projected from a substrate that exists only in lower dimensions.

This 'holographic principle' is strange even by the usual standards of theoretical physics. But Van Raamsdonk is one of a small band of researchers who think that the usual ideas are not yet strange enough. If nothing else, they say, neither of the two great pillars of modern physics — general relativity, which describes gravity as a curvature of space and time, and quantum mechanics, which governs the atomic realm — gives any account for the existence of space and time. Neither does string theory, which describes elementary threads of energy.

One of the most obvious questions to ask is whether this endeavour is a fool's errand. Where is the evidence that there actually is anything more fundamental than space and time?

A provocative hint comes from a series of startling discoveries made in the early 1970s, when it became clear that quantum mechanics and gravity were intimately intertwined with thermodynamics, the science of heat.

Even if it is correct, the thermodynamic approach says nothing about what the fundamental constituents of space and time might be. If space-time is a fabric, so to speak, then what are its threads?

One possible answer is quite literal. The theory of loop quantum gravity, which has been under development since the mid-1980s by Ashtekar and others, describes the fabric of space-time as an evolving spider's web of strands that carry information about the quantized areas and volumes of the regions they pass through6. The individual strands of the web must eventually join their ends to form loops — hence the theory's name — but have nothing to do with the much better-known strings of string theory. The latter move around in space-time, whereas strands actually are space-time: the information they carry defines the shape of the space-time fabric in their vicinity.

Nature: Theoretical physics: The origins of space and time

THIS is why I joined the Air Force...

...yes, I'm a veteran.

Physics arXiv

I was a Communications/Computer Systems Officer (though not nearly as attractive in uniform as Uhura, or her reboot). Then, and now, it was the youngest branch of the armed services, and the one that seemed to think in future-tense.

On the Physics arXiv link, the Air Force seems to be working on quantum computing with holograms, and according to the post, they can do it with off-the-shelf tech (like, Radio Shack, my next favorite place other than the library). Reading the paper, they seem to talk a lot about quantum teleportation.

I checked: sadly, not carried by "The Shack," but products at OptiGrate Corporation out of Florida. Probably NOT cheap!

Star Trek database: Descent, Part I

Physics arXiv: Quantum computing in a piece of glass