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Scientists Catch A Glimpse Of A Four-Dimension

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Two independent groups of scientists have been able to reproduce four-dimensional properties of a quantum mechanical effect using a two-dimensional analog.

The two studies were published in Nature (here and here) and focus on the quantum Hall effect. This effect describes how the conductance (how well something transmits electricity) of a two-dimensional electron system acts at a low temperature and in a strong magnetic field. It has been known for a long time that this effect could also exist in a four-dimensional system, but this has not been possible to prove until now.

"When it was theorized that the quantum Hall effect could be observed in four-dimensional space, it was considered to be of purely theoretical interest because the real world consists of only three spatial dimensions; it was more or less a curiosity, " Mikael Rechtsman, assistant professor of physics and author of one of the papers, said in a statement. "But, we have now shown that four-dimensional quantum Hall physics can be emulated using photons – particles of light – flowing through an intricately structured piece of glass – a waveguide array."

The waveguide set-up used to test the 4D quantum Hall effect. Rechtsman laboratory, Penn State University

Thanks to a new technique, glass waveguides can be etched in a way that makes them sport synthetic dimensions, allowing photons going through the waveguides to act like they are in a true four-dimensional system. This breakthrough allowed researchers to finally test if the quantum Hall effect truly exists in four dimensions. And it does.

The effect cannot be observed in three dimensions. It was first observed in two dimensions when electrical charges were sandwiched between two surfaces. Once the surface cools to almost absolute zero and is subjected to a strong magnetic field, the amount of charge that it can transmit is quantized, fixed by the fundamental quantities of nature.

"Quantization is striking because even if the material is 'messy' – that is, it has a lot of defects – this 'Hall conductance' remains exceedingly stable," said Rechtsman. "This robustness of electron flow – the quantum Hall effect – is universal and can be observed in many different materials under very different conditions."

While there are no direct applications of four-dimensional physics, the scientists think that a better understanding of the four-dimensional quantum Hall effect could be used to develop new optical systems, and maybe the use of higher dimensional waveguides could help explain bizarre solids like quasicrystals.

Article was originally published on IFLScience.com.

Hidden Dimensions Might Exist In Gravitational Waves Say Experts

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Researchers from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) in Potsdam found that hidden dimensions – as predicted by string theory – could influence gravitational waves.

Hidden dimensions are one of the most popular subjects in science fiction movies, but apparently, not everything is made up. Even though scientists have still not been able to find them, String Theory predicts hidden dimensions do EXIST.

According to a new research at the Max Planck Institute for Gravitational Physics of the Albert Einstein Institute (AEI), hidden dimensions may influence something experts might detect: Gravitational Waves. If this is proven to be true, if experts study the ripples in space-time, they just might unlock the mystery of hidden dimensions and prove they do exist.

The new study takes a look at the characteristics and consequences extra dimensions may have on gravitational waves, offering predictions whether or not scientists on Earth could detect their presence.

LIGO, Gravitational Wave, and Extra dimensions

As noted in the study, LIGO’s first detection of gravitational waves from a black-hole binary in September 2015 has opened a new window onto the universe. Now it looks like with this new observing tool physicists cannot only trace black holes and other exotic astrophysical objects but also understand gravity itself.

“Compared to the other fundamental forces like, e.g. electromagnetism, gravity is extremely weak,” explains Dr. David Andriot, one of the authors of the study. The reason for this weakness could be that gravity interacts with more than the three dimensions in space and one dimension in time that are part of our everyday experience.

LIGO has opened a new window for astronomy detecting stellar-mass black holes larger than 20 solar masses. The success of LIGO has given birth to LISA, an in space manifestation of LIGO which will help experts expand their studies on supermassive black holes and another cosmic phenomenon.

Experts will use LIGO’s observations not only to trace and locate Black Holes but to research and explain gravity itself.

Experts say that the relatively weak force of gravity may be the result of interactions between hidden dimensions. Astronomers suspect that if hidden dimensions do exist, would modify “standard” gravitational waves and cause additional waves above 1,000 Hz.

As noted by Futurism, it seems unlikely that we could observe the latter phenomenon (not from Earth, anyway) but introducing more than one detector into the mix might improve our chances.

“The effect that extra dimensions can make a difference in how “standard” gravitational waves stretch and shrink space-time might be easier to detect by making use of more than one detector.”

Searching for extra dimensions with all available tools

In the past experts at the Large Hadron Collider at CERN have tried finding evidence of the existence of hidden dimensions but with little luck.

“Physicists have been looking for extra dimensions at the Large Hadron Collider at CERN but up to now this search has yielded no results,” says Dr. Gustavo Lucena Gómez, the second author of the paper. But gravitational wave detectors might be able to provide experimental evidence.”

(H/T Futurism)

Source: Max Planck Institute for Gravitational Physics

"The Big Bang Was A Mirage From A Collapsing Higher-Dimensional Star"

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Big Bang was a mirage from collapsing higher-dimensional star, theorists propose. While the recent Planck results “prove that inflation is correct”, they leave open the question of how inflation happened. A new The study could help to show how inflation was triggered by the motion of the Universe through a higher-dimensional reality.

The event horizon of a black hole — the point of no return for anything that falls in — is a spherical surface. In a higher-dimensional universe, a black hole could have a three-dimensional event horizon, which could spawn a whole new universe as it forms.

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.

To most cosmologists, the most plausible explanation for that uniformity is that, soon after the beginning of time, some unknown form of energy made the young Universe inflate at a rate that was faster than the speed of light. That way, a small patch with roughly uniform temperature would have stretched into the vast cosmos we see today. But Afshordi notes that “the Big Bang was so chaotic, it’s not clear there would have been even a small homogenous patch for inflation to start working on”.

In a paper posted in the arXiv preprint server1, Afshordi and his colleagues turn their attention to a proposal made in 2000 by a team including Gia Dvali, a physicist now at the Ludwig Maximilians University in Munich, Germany. In that model, our three-dimensional (3D) Universe is a membrane, or brane, that floats through a ‘bulk universe’ that has four spatial dimensions.

Ashfordi's team realized that if the bulk universe contained its own four-dimensional (4D) stars, some of them could collapse, forming 4D black holes in the same way that massive stars in our Universe do: they explode as supernovae, violently ejecting their outer layers, while their inner layers collapse into a black hole.

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.

The model also naturally explains our Universe’s uniformity. Because the 4D bulk universe could have existed for an infinitely long time in the past, there would have been ample opportunity for different parts of the 4D bulk to reach an equilibrium, which our 3D Universe would have inherited.

The picture has some problems, however. Earlier this year, the European Space Agency's Planck space observatory released data that mapped the slight temperature fluctuations in the cosmic microwave background — the relic radiation that carries imprints of the Universe’s early moments. The observed patterns matched predictions made by the standard Big Bang model and inflation, but the black-hole model deviates from Planck's observations by about 4%. Hoping to resolve the discrepancy, Afshordi says that his is now refining its model.

Despite the mismatch, Dvali praises the ingenious way in which the team threw out the Big Bang model. “The singularity is the most fundamental problem in cosmology and they have rewritten history so that we never encountered it,” he says. Whereas the Planck results “prove that inflation is correct”, they leave open the question of how inflation happened, Dvali adds. The study could help to show how inflation is triggered by the motion of the Universe through a higher-dimensional reality, he says.

Nature doi:10.1038/nature.2013.13743

Via Zeeya Merali/nature.com and The Perimeter Institute

Image credit: The Perimeter Institute

Watch Michio Kaku Explain The 11 Dimensions Of The Multiverse

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Theoretical physicist Michio Kaku has initiated the conversation as to why other universes in the multiverse could have many more dimensions, and has spoken out on the multiverse having 11 dimensions. Though merely theory, as has yet to be proven, it is an interesting one to reflect on nonetheless.

What exactly IS the multiverse?

The multiverse is the hypothetical set of possible universes, including the universe which we live in. Together, these universes comprise everything that exists: the entirety of space, time, matter, energy, and the physical laws and constants that describe them.

If we were, hypothetically, a mere fragment of a multitude of universes in which many dimensions existed, what does that say about our present perception of reality? How can we go about looking at this deeper and further understanding what this could mean for us as humans, a collective and our planet?

Michio Kaku states: We believe, though we cannot yet prove, that our multiverse of universes is 11-dimensional. So think of this 11-dimensional arena and in this arena there are bubbles, bubbles that float and the skin of the bubble represents an entire universe, so we’re like flies trapped on fly paper. We’re on the skin of a bubble. It’s a three dimensional bubble. The three dimensional bubble is expanding and that is called the Big Bang theory and sometimes these bubbles can bump into each other, sometimes they can split apart and that we think is the Big Bang. So we even have a theory of the Big Bang itself. Now you ask a question what about the dimensions of each bubble. Well in string theory—which is what I do for a living; that’s my day job—In string theory we can have bubbles of different dimensions. The highest dimension is 11. You cannot go beyond 11 because universes become unstable beyond 11. If I write down the theory of a 13-, 15-dimensional universe it’s unstable and it collapses down to an 11-dimensional universe. But within 11 dimensions you can have bubbles that are 3 dimensional, 4-dimensional, 5-dimensional. These are membranes, so for short we call them brains. So these brains can exist in different dimensions and let’s say P represents the dimension of each bubble, so we call them p-brains. So a p-brain is a universe in different dimensions floating in a much larger arena, and this larger arena is the hyperspace that I talked about originally. Also remember that each bubble vibrates, and each bubble vibrating creates music. The music of these membranes is the subatomic particles. Each subatomic particle represents a note on a vibrating string or vibrating membranes. So, believe it or not, we now have a candidate for the “Mind of God” that Albert Einstein wrote about for the last 30 years of his life. The “Mind of God” in this picture would be cosmic music resonating throughout 11-dimensional hyperspace.

Experiments Show The Effects of a Fourth Spatial Dimension

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We're used to dealing with three physical dimensions and one extra dimension of time as we move through the Universe, but two teams of scientists have shown that a fourth spatial dimension could reach beyond the limits of up and down, left and right, and forwards and backwards.

As you might expect given this is bending the laws of physics, the experiments involved are partly theoretical and very complex, and touch on our old friend quantum mechanics.

By placing together two specially designed 2D setups, two separate teams of researchers - one in Europe and one in the US - were able to catch a glimpse of this fourth spatial dimension through what's known as the quantum Hall effect, a certain way of restricting and measuring electrons.

"Physically, we don't have a 4D spatial system, but we can access 4D quantum Hall physics using this lower-dimensional system because the higher-dimensional system is coded in the complexity of the structure," a researcher with the US-based team, Mikael Rechtsman from Penn State University, told Ryan F. Mandelbaum at Gizmodo.

"Maybe we can come up with new physics in the higher dimension and then design devices that take advantage the higher-dimensional physics in lower dimensions."

In other words, just as a 3D object casts a 2D shadow, scientists have managed to observe a 3D shadow potentially cast by a 4D object – even if we can't actually see the 4D object itself. That could unlock some new findings in the very fundamentals of science.

Thanks to some rather advanced calculations – which won the Nobel Prize for Physics in 2016 – we know that the quantum Hall effect points to the existence of a fourth spatial dimension.

What these new experiments do is give us a picture of the effects that this fourth dimension might have.

The European team's setup involved atoms cooled down close to absolute zero and placed in a 2D lattice through the user of lasers, described as "an egg-carton-like crystal of light" by the researchers.

With the addition of extra lasers, the team was able to implement a quantum "charge pump" to excite the trapped atoms and get them moving. Slight variations in the movement spotted by the researchers match up with how a 4D quantum Hall effect would ripple out – adding weight to the possibility that a fourth spatial dimension can be somehow accessed.

The US experiment also used lasers, this time to control light as it flowed through a block of glass. By manipulating the light to simulate the effect of an electric field on charged particles, again the consequences of a 4D quantum Hall effect could be observed.

Of course, we can't physically access this 4D world – we're stuck in 3D space – but scientists think quantum mechanics could somehow give us a picture of it, thus enhancing our limited understanding of the Universe.

Another way to think about it, courtesy of this video, is if we were video game characters from a 2D platform, and suddenly wandering around in a 3D game. Our perspective would stay 2D, but as we moved around we would see distortions and flips as the 3D world was folded into a 2D plane.

The same kind of distortions have been shown in this study, hinting at a bigger 4D world outside what we can see right now.

So we can't take a trip to the fourth spatial dimension just yet – but we've got more evidence that it's out there, and a better idea how how it works.

The team of researchers now wants to build on these studies to take a closer look, and to maybe explore some even more advanced physics along the way.

"I think that the two experiments nicely complement each other," one of the European researchers, Michael Lohse from the Ludwig-Maximilians University in Germany, told Gizmodo.

Article Courtesy ScienceAlert.

The findings from the two experiments have been published in Nature here and here.