Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: quantum physics – Page 434

Circa 2015 o.o!

The publication of Green and Schwarz’s paper “was 30 years ago this month,” the string theorist and popular-science author Brian Greene wrote in Smithsonian Magazine in January, “making the moment ripe for taking stock: Is string theory revealing reality’s deep laws? Or, as some detractors have claimed, is it a mathematical mirage that has sidetracked a generation of physicists?” Greene had no answer, expressing doubt that string theory will “confront data” in his lifetime.

Recently, however, some string theorists have started developing a new tactic that gives them hope of someday answering these questions. Lacking traditional tests, they are seeking validation of string theory by a different route. Using a strange mathematical dictionary that translates between laws of gravity and those of quantum mechanics, the researchers have identified properties called “consistency conditions” that they say any theory combining quantum mechanics and gravity must meet. And in certain highly simplified imaginary worlds, they claim to have found evidence that the only consistent theories of “quantum gravity” involve strings.

According to many researchers, the work provides weak but concrete support for the decades-old suspicion that string theory may be the only mathematically consistent theory of quantum gravity capable of reproducing gravity’s known form on the scale of galaxies, stars and planets, as captured by Albert Einstein’s theory of general relativity. And if string theory is the only possible approach, then its proponents say it must be true — with or without physical evidence. String theory, by this account, is “the only game in town.”

Continue reading “In Fake Universes, Evidence for String Theory” | >

Circa 2014 o.o!

When someone mentions “different dimensions,” we tend to think of things like parallel universes – alternate realities that exist parallel to our own, but where things work or happened differently. However, the reality of dimensions and how they play a role in the ordering of our Universe is really quite different from this popular characterization.

To break it down, dimensions are simply the different facets of what we perceive to be reality. We are immediately aware of the three dimensions that surround us on a daily basis – those that define the length, width, and depth of all objects in our universes (the x, y, and z axes, respectively).

Beyond these three visible dimensions, scientists believe that there may be many more. In fact, the theoretical framework of Superstring Theory posits that the universe exists in ten different dimensions. These different aspects are what govern the universe, the fundamental forces of nature, and all the elementary particles contained within.

Continue reading “A universe of 10 dimensions” | >

A theoretical study shows that long-range entanglement can indeed survive at temperatures above absolute zero, if the correct conditions are met.

Quantum computing has been earmarked as the next revolutionary step in computing. However current systems are only practically stable at temperatures close to absolute zero. A new theorem from a Japanese research collaboration provides an understanding of what types of long-range quantum entanglement survive at non-zero temperatures, revealing a fundamental aspect of macroscopic quantum phenomena and guiding the way towards further understanding of quantum systems.

When things get small, right down to the scale of one-thousandth the width of a human hair, the laws of classical physics get replaced by those of . The quantum world is weird and wonderful, and there is much about it that scientists have yet to understand. Large-scale or “macroscopic” quantum effects play a key role in extraordinary phenomena such as superconductivity, which is a potential game-changer in future energy transport, as well for the continued development of quantum computers.

Read more | >

The development of experimental platforms that advance the field of quantum science and technology (QIST) comes with a unique set of advantages and challenges common to any emergent technology. Researchers at Stony Brook University, led by Dominik Schneble, PhD, report the formation of matter-wave polaritons in an optical lattice, an experimental discovery that permits studies of a central QIST paradigm through direct quantum simulation using ultracold atoms. The scientists project that their novel quasiparticles, which mimic strongly interacting photons in materials and devices but circumvent some of the inherent challenges, will benefit the further development of QIST platforms that are poised to revolutionize computing and communication technology.

The research findings are detailed in a paper published in the journal Nature Physics.

The study sheds light on fundamental polariton properties and related many-body phenomena, and it opens up novel possibilities for studies of polaritonic quantum matter.

Read more | >

The physics of the microrealm involves two famous and bizarre concepts: The first is that prior to observation, it is impossible to know with certainty the outcome of a measurement on a particle; rather the particle exists in a “superposition” encompassing multiple mutually exclusive states. So a particle can be in two or more places at the same time, and you can only calculate the probability of finding it in a certain location when you look. The second involves “entanglement,” the spooky link that can unite two objects, no matter how far they are separated. Both superposition and entanglement are described mathematically by quantum theory. But many physicists believe that the ultimate theory of reality may lie beyond quantum theory. Now, a team of physicists and mathematicians has discovered a new connection between these two weird properties that does not assume that quantum theory is correct. Their study appears in Physical Review Letters.

“We were really excited to find this new connection that goes beyond quantum theory because the connection will be valid even for more exotic theories that are yet to be discovered,” says Ludovico Lami, a member of the physics think-tank, the Foundational Questions Institute, FQXi, and a physicist at the University of Ulm, in Germany. “This is also important because it is independent of the mathematical formalism of quantum theory and uses only notions with an immediate operational interpretation,” he adds. Lami co-authored the study with Guillaume Aubrun of Claude Bernard University Lyon 1, in France, Carlos Palazuelos, of the Complutense University of Madrid, in Spain, and Martin Plávala, of Siegen University, in Germany.

While quantum theory has proven to be supremely successful since its development a century ago, physicists have struggled to unify it with gravity to create one overarching “theory of everything.” This suggests that quantum theory may not be the final word on describing reality, inspiring physicists to hunt for a more fundamental framework. But any such ultimate theory must still incorporate superposition, entanglement, and the probabilistic nature of reality, since these features have been confirmed time and again in lab tests. The interpretation of these experiments does not depend on quantum theory being correct, notes Lami.

Read more | >

Abstract: Spin-two particles appear in the spectra of both open and closed string theories. We studied a graviton and massive symmetric rank-two tensor in string theory, both of which carry spin two. A graviton is a massless spin-two particle in closed string theory while a symmetric rank-two tensor is a massive particle with spin two in open string theory. Using Polyakov’s string path integral formulation of string scattering amplitudes, we calculated cubic interactions of both spin-two particles explicitly, including $\ap$-corrections (string corrections). We observed that the cubic interactions of the massive spin-two particle differed from those of the graviton. The massive symmetric rank-two tensor in open string theory becomes massless in the high energy limit where $\ap \rightarrow \infty$ and $\ap$-correction terms, containing higher derivatives, dominate: In this limit the local cubic action of the symmetric rank-two tensor of open string theory coincides with that of the graviton in closed string theory.

From: Taejin Lee [view email].

Read more | >

The team, part of Surrey’s research program in the exciting new field of quantum biology, have shown that this modification in the bonds between the DNA strands is far more prevalent than has hitherto been thought. The protons can easily jump from their usual site on one side of an energy barrier to land on the other side. If this happens just before the two strands are unzipped in the first step of the copying process, then the error can pass through the replication machinery in the cell, leading to what is called a DNA mismatch and, potentially, a mutation.

In a paper published this week in the journal Communications Physics, the Surrey team based in the Leverhulme Quantum Biology Doctoral Training Center used an approach called open quantum systems to determine the physical mechanisms that might cause the protons to jump across between the DNA strands. But, most intriguingly, it is thanks to a well-known yet almost magical quantum mechanism called tunneling—akin to a phantom passing through a solid wall—that they manage to get across.

The molecules of life, DNA, replicate with astounding precision, yet this process is not immune to mistakes and can lead to mutations. Using sophisticated computer modeling, a team of physicists and chemists at the University of Surrey have shown that such errors in copying can arise due to the strange rules of the quantum world.

The two strands of the famous DNA double helix are linked together by called protons—the nuclei of atoms of hydrogen—which provide the glue that bonds molecules called bases together. These so-called are like the rungs of a twisted ladder that makes up the structure discovered in 1952 by James Watson and Francis Crick based on the work of Rosalind Franklin and Maurice Wilkins.

Continue reading “Quantum mechanics could explain why DNA can spontaneously mutate” | >

The future of astronomy goes far beyond the James Webb Space Telescope.

For example, it’s theoretically possible to use quantum computers as a means for constructing colossal, planet-sized telescopes, according to a study shared to a preprint server and initially reported by New Scientist.

And, if we could make it work, a planetary telescope would peer much farther into the big black abyssal depths of space, and image the distant universe at untold levels of resolution.

Read more | >

Quantum machine learning is a field of study that investigates the interaction of concepts from quantum computing with machine learning.

For example, we would wish to see if quantum computers can reduce the amount of time it takes to train or assess a machine learning model. On the other hand, we may use machine learning approaches to discover quantum error-correcting algorithms, estimate the features of quantum systems, and create novel quantum algorithms.

Read more | >

Consciousness defines our existence. It is, in a sense, all we really have, all we really are, The nature of consciousness has been pondered in many ways, in many cultures, for many years. But we still can’t quite fathom it.

web1Why consciousness cannot have evolved

Consciousness Cannot Have Evolved Read more Consciousness is, some say, all-encompassing, comprising reality itself, the material world a mere illusion. Others say consciousness is the illusion, without any real sense of phenomenal experience, or conscious control. According to this view we are, as TH Huxley bleakly said, ‘merely helpless spectators, along for the ride’. Then, there are those who see the brain as a computer. Brain functions have historically been compared to contemporary information technologies, from the ancient Greek idea of memory as a ‘seal ring’ in wax, to telegraph switching circuits, holograms and computers. Neuroscientists, philosophers, and artificial intelligence (AI) proponents liken the brain to a complex computer of simple algorithmic neurons, connected by variable strength synapses. These processes may be suitable for non-conscious ‘auto-pilot’ functions, but can’t account for consciousness.

Finally there are those who take consciousness as fundamental, as connected somehow to the fine scale structure and physics of the universe. This includes, for example Roger Penrose’s view that consciousness is linked to the Objective Reduction process — the ‘collapse of the quantum wavefunction’ – an activity on the edge between quantum and classical realms. Some see such connections to fundamental physics as spiritual, as a connection to others, and to the universe, others see it as proof that consciousness is a fundamental feature of reality, one that developed long before life itself.

Read more | >