The main problems of canonical quantum cosmology are the following

The main problems of canonical quantum cosmology are the following:

The singularity. The Wheeler-DeWitt equation does not remove the singularity, although in some cases the solutions avoid the singularity due to the effective potential as we have seen. In short, canonical quantum gravity is not well defined. The models of canonical quantum cosmology do only apply on a semiclassical approximation and there is no way to make predictions about the dynamics of the singularity.

Decoherence. If the wavefunction of the universe is a linear combination of basic states, then these can interfere with each other. However, we observe a classical universe without interference on the macrocospic world. This requires of a mechanism to allow for decoherence of the wavefunction of the universe.

The problem of time. This is more a general problem in the canonical approach of quantum gravity, but its implications are important in cosmology. The Hamiltonian constraint indicates that the theory does not have a predefined notion of time. Reparametrizations of the time evolution are gauge transformations without physical content. To single out the real time evolution of the universe one has to fix a specific gauge. This breaks the original symmetry of the classical equations under diffeomorphisms and, moreover, different choices of different time variables lead to different quantum theories. The question that arises is related to the next issue: are we allowed to select the scale factor as a parameter that scans time evolution already in the quantum regime?

The minisuperspace approximation. The minisuperspace approximation does fix simultaneously canonically conjugate variables violating the uncertainty principle (due to symmetry the dynamic variable and its conjugate momentum are both zero). It leaves the scale factor as the single degree of freedom in the models. Although our universe is currently homogenous and isotropic, this assumption need not to be valid at the beginning. Note that the inflationary phase, already in the classical regime, might have created homogeneity out of an inhomogeneous and random initial state.

Inhomogeneities. There exist models that describe inhomogeneities, but they are poorly understood.

Initial conditions. Initial conditions that are imposed to the universe cannot be derived from any principle and become the same status than fundamental laws. Bryce DeWitt envisioned a theory in which the requirement of mathematical consistency should be sufficient to guarantee a unique solution to the Wheeler-deWitt equation. However, this cannot be realized in canonical quatum cosmology.

Formalism. The theory has diverse mathematical and consistency problems, like factor ordering and other ambiguities, and the definition of a proper notion of probabilites in a single universe.

Nevertheless, one would expect that some aspects of the mentioned canonical quantum cosmology models should be present in a complete and consistent model of quantum cosmology. There is no clear reason to expect the description of the origin of the universe beyond the singularity to be correct, but the calculations for transition probabilities and set-up of inflation near the classical regime may be a good approximation to reality.

(Sharing Credits with Herr von Bradford)

Cosmic Seeding

Most of the universe's heavy elements, including the iron central to life itself, formed early in cosmic history and spread throughout the universe, according to a new study of the Perseus Galaxy Cluster using Japan's Suzaku satellite.

Suzaku study points to early cosmic 'seeding': http://phy.so/302434001

(Phys.org) —Most of the universe's heavy elements, including the iron central to life itself, formed early in cosmic history and spread throughout the universe, according to a new study of the Perseus Galaxy Cluster using Japan's Suzaku satellite.

Graviton

I have been refreshing myself on quantum gravity, renormalization and the concept of gravitons being experimentally confirmed all morning. This is an interesting article I found on how physicist could find the highly theoretical particle called the graviton. They could use a particle accelerator to create a proton antiproton collision. This collision would result into gravitons decaying into standard model particles.

I have been refreshing myself on quantum gravity, renormalization and the concept of gravitons being experimentally confirmed all morning. This is an interesting article I found on how physicist could find the highly theoretical particle called the graviton. They could use a particle accelerator to create a proton antiproton collision. This collision would result into gravitons decaying into standard model particles. http://www-d0.fnal.gov/Run2Physics/WWW/results/final/NP/N05C/N05C.html

Quantum Tunneling

Quantum Tunneling: A World Stranger Than Science Fiction Think for a moment about a ball rolling up a hill. If you don’t push hard enough, then it will not roll over the hill. This makes sense classically. However, in quantum mechanics, an object does not behave like a classical object (such as ball, or you, or I, or any matter in the universe does). Learn about the strange world we live in at:

http://www.fromquarkstoquasars.com/?p=15680

Scientists reveal cosmic roadmap to galactic magnetic field

Scientists reveal cosmic roadmap to galactic magnetic field: http://phy.so/311514082

Scientists on NASA's Interstellar Boundary Explorer (IBEX) mission, including a team leader from the University of New Hampshire, report that recent, independent measurements have validated one of the mission's signature findings—a mysterious "ribbon" of energy and particles at the edge of our solar system that appears to be a directional "roadmap in the sky" of the local interstellar magnetic field.

Nuclear-atomic overlap for the isotope thorium-229

Nuclear-atomic overlap for the isotope thorium-229: http://phy.so/311851967

More than 99.9% of the mass of any atom is concentrated into a quadrillionth of its volume, the part occupied by the nucleus. Unimaginably small, dense and energetic, atomic nuclei are governed by laws quite distinct from those that regulate atomic electrons, which constitute the outer part of atoms and which are immediately responsible for light, chemistry and thus life. Yet there are sporadic regions of contact between these disparate realms. JQI Adjunct Fellow Marianna Safronova and her collaborators (1) have been exploring one area of nuclear-atomic overlap for the isotope thorium-229. This isotope is a candidate for a new type of atomic clock and quantum information processor.

Standard Model of Fundamental Particles and Interactions.

Standard Model of Fundamental Particles and Interactions.

(But without the Higgs boson, most certainly because it wasn't discovered yet when this poster was created).

Link to high res here: http://www.phy.duke.edu/research/NPTheory/particle_chart2.jpg

"The Basic Elements of String Theory"

"The Basic Elements of String Theory"

Five key ideas are at the heart of string theory. Become familiar with these key elements of string theory right off the bat. Read on for the very basics of these five ideas of string theory in the sections below.

1.Strings and membranes-

When the theory was originally developed in the 1970s, the filaments of energy in string theory were considered to be 1-dimensional objects: strings. (One-dimensional indicates that a string has only one dimension, length, as opposed to say a square, which has both length and height dimensions.)

These strings came in two forms — closed strings and open strings. An open string has ends that don’t touch each other, while a closed string is a loop with no open end. It was eventually found that these early strings, called Type I strings, could go through five basic types of interactions, as shown in the figure.

Type I strings can go through five fundamental interactions, based on different ways of joining and splitting.

The interactions are based on a string’s ability to have ends join and split apart. Because the ends of open strings can join together to form closed strings, you can’t construct a string theory without closed strings.

This proved to be important, because the closed strings have properties that make physicists believe they might describe gravity. Instead of just being a theory of matter particles, physicists began to realize that string theory may just be able to explain gravity and the behavior of particles.

Over the years, it was discovered that the theory required objects other than just strings. These objects can be seen as sheets, or branes. Strings can attach at one or both ends to these branes. A 2-dimensional brane (called a 2-brane) is shown in this figure.

In string theory, strings attach themselves to branes.

2.Quantum gravity-

Modern physics has two basic scientific laws: quantum physics and general relativity. These two scientific laws represent radically different fields of study. Quantum physics studies the very smallest objects in nature, while relativity tends to study nature on the scale of planets, galaxies, and the universe as a whole. (Obviously, gravity affects small particles too, and relativity accounts for this as well.) Theories that attempt to unify the two theories are theories of quantum gravity, and the most promising of all such theories today is string theory.

3.Unification of forces-

Hand-in-hand with the question of quantum gravity, string theory attempts to unify the four forces in the universe — electromagnetic force, the strong nuclear force, the weak nuclear force, and gravity — together into one unified theory. In our universe, these fundamental forces appear as four different phenomena, but string theorists believe that in the early universe (when there were incredibly high energy levels) these forces are all described by strings interacting with each other.

4.Supersymmetry-

All particles in the universe can be divided into two types: bosons and fermions. String theory predicts that a type of connection, called supersymmetry, exists between these two particle types. Under supersymmetry, a fermion must exist for every boson and vice versa. Unfortunately, experiments have not yet detected these extra particles.

Supersymmetry is a specific mathematical relationship between certain elements of physics equations. It was discovered outside of string theory, although its incorporation into string theory transformed the theory into supersymmetric string theory (or superstring theory) in the mid-1970s.

Supersymmetry vastly simplifies string theory’s equations by allowing certain terms to cancel out. Without supersymmetry, the equations result in physical inconsistencies, such as infinite values and imaginary energy levels.

Because scientists haven’t observed the particles predicted by supersymmetry, this is still a theoretical assumption. Many physicists believe that the reason no one has observed the particles is because it takes a lot of energy to generate them. (Energy is related to mass by Einstein’s famous E = mc2 equation, so it takes energy to create a particle.) They may have existed in the early universe, but as the universe cooled off and energy spread out after the big bang, these particles would have collapsed into the lower-energy states that we observe today. (We may not think of our current universe as particularly low energy, but compared to the intense heat of the first few moments after the big bang, it certainly is.)

Scientists hope that astronomical observations or experiments with particle accelerators will uncover some of these higher-energy supersymmetric particles, providing support for this prediction of string theory.

6.Extra dimensions-

Another mathematical result of string theory is that the theory only makes sense in a world with more than three space dimensions! (Our universe has three dimensions of space — left/right, up/down, and front/back.) Two possible explanations currently exist for the location of the extra dimensions:

The extra space dimensions (generally six of them) are curled up (compactified, in string theory terminology) to incredibly small sizes, so we never perceive them.

We are stuck on a 3-dimensional brane, and the extra dimensions extend off of it and are inaccessible to us.

From_ String Theory For Dummies

-Dr. B

A major area of research among string theorists is on mathematical models of how these extra dimensions could be related to our own. Some of these recent results have predicted that scientists may soon be able to detect these extra dimensions (if they exist) in upcoming experiments, because they may be larger than previously expected.

theoretical gravitation particle

There’s another theoretical gravitation particle, and it is quite intriguing. The graviphoton is a particle that would be created when the gravitational field is excited in a fifth dimension. It comes from the Kaluza Klein theory, which proposes that electromagnetism and gravitation can be unified into a single force under the condition that there are more than four dimensions in spacetime. A graviphoton would have the characteristics of a graviton, but it would also carry the properties of a photon and create what physicists call a “fifth force” (there are currently four fundamental forces). Other theories state that a graviphoton would be a superpartner (like a sparticle) of gravitons, but that it would actually attract and repel at the same time. By doing that, gravitons could theoretically create anti-gravity. And that’s only in the fifth dimension—the theory of supergravity also posits the existence of graviphotons, but allows for eleven dimensions.

I will start this post off by saying that this is in the realm of Theoretical Physics. There’s another theoretical gravitation particle, and it is quite intriguing. The graviphoton is a particle that would be created when the gravitational field is excited in a fifth dimension. It comes from the Kaluza Klein theory, which proposes that electromagnetism and gravitation can be unified into a single force under the condition that there are more than four dimensions in spacetime. A graviphoton would have the characteristics of a graviton, but it would also carry the properties of a photon and create what physicists call a “fifth force” (there are currently four fundamental forces). Other theories state that a graviphoton would be a superpartner (like a sparticle) of gravitons, but that it would actually attract and repel at the same time. By doing that, gravitons could theoretically create anti-gravity. And that’s only in the fifth dimension—the theory of supergravity also posits the existence of graviphotons, but allows for eleven dimensions.

The Successes of String Theory

The Successes of String Theory

String theory has gone through many transformations since its origins in 1968 when it was hoped to be a model of certain types of particle collisions. It initially failed at that goal, but in the 40 years since, string theory has developed into the primary candidate for a theory of quantum gravity. It has driven major developments in mathematics, and theorists have used insights from string theory to tackle other, unexpected problems in physics. In fact, the very presence of gravity within string theory is an unexpected outcome!

Predicting gravity out of strings

The first and foremost success of string theory is the unexpected discovery of objects within the theory that match the properties of the graviton. These objects are a specific type of closed strings that are also massless particles that have spin of 2, exactly like gravitons. To put it another way, gravitons are a spin-2 massless particle that, under string theory, can be formed by a certain type of vibrating closed string. String theory wasn’t created to have gravitons — they’re a natural and required consequence of the theory.

One of the greatest problems in modern theoretical physics is that gravity seems to be disconnected from all the other forces of physics that are explained by the Standard Model of particle physics. String theory solves this problem because it not only includes gravity, but it makes gravity a necessary byproduct of the theory.

Explaining what happens to a black hole (sort of)

A major motivating factor for the search for a theory of quantum gravity is to explain the behavior of black holes, and string theory appears to be one of the best methods of achieving that goal. String theorists have created mathematical models of black holes that appear similar to predictions made by Stephen Hawking more than 30 years ago and may be at the heart of resolving a long-standing puzzle within theoretical physics: What happens to matter that falls into a black hole?

Scientists’ understanding of black holes has always run into problems, because to study the quantum behavior of a black hole you need to somehow describe all the quantum states (possible configurations, as defined by quantum physics) of the black hole. Unfortunately, black holes are objects in general relativity, so it’s not clear how to define these quantum states.

String theorists have created models that appear to be identical to black holes in certain simplified conditions, and they use that information to calculate the quantum states of the black holes. Their results have been shown to match Hawking’s predictions, which he made without any precise way to count the quantum states of the black hole.

This is the closest that string theory has come to an experimental prediction. Unfortunately, there’s nothing experimental about it because scientists can’t directly observe black holes (yet). It’s a theoretical prediction that unexpectedly matches another (well-accepted) theoretical prediction about black holes. And, beyond that, the prediction only holds for certain types of black holes and has not yet been successfully extended to all black holes.

Explaining quantum field theory using string theory

One of the major successes of string theory is something called the Maldacena conjecture, or the AdS/CFT correspondence. Developed in 1997 and soon expanded on, this correspondence appears to give insights into gauge theories, such as those at the heart of quantum field theory.

The original AdS/CFT correspondence, written by Juan Maldacena, proposes that a certain 3-dimensional (three space dimensions, like our universe) gauge theory, with the most supersymmetry allowed, describes the same physics as a string theory in a 4-dimensional (four space dimensions) world. This means that questions about string theory can be asked in the language of gauge theory, which is a quantum theory that physicists know how to work with!

Like John Travolta, string theory keeps making a comeback

String theory has suffered more setbacks than probably any other scientific theory in the history of the world, but those hiccups don’t seem to last that long. Every time it seems that some flaw comes along in the theory, the mathematical resiliency of string theory seems to not only save it, but to bring it back stronger than ever.

When extra dimensions came into the theory in the 1970s, the theory was abandoned by many, but it had a comeback in the first superstring revolution. It then turned out there were five distinct versions of string theory, but a second superstring revolution was sparked by unifying them. When string theorists realized a vast number of solutions of string theories (each solution to string theory is called a vacuum, while many solutions are called vacua) were possible, they turned this into a virtue instead of a drawback. Unfortunately, even today, some scientists believe that string theory is failing at its goals.

3 parts series on supersymmetry

3 parts series on supersymmetry

Nice reading for SUSY fans, check it out:

part 1

http://www.quantumdiaries.org/2014/03/14/the-standard-model-a-beautiful-but-flawed-theory/

part 2 http://www.quantumdiaries.org/2014/03/19/supersymmetry-a-tantalising-theory/

part 3

http://www.quantumdiaries.org/2014/03/21/has-anybody-seen-my-supersymmetric-particles/

About the nature of time and time travel

About the nature of time and time travel

Think about the nature of time at first!

Time is related to motion and duration. There is no time as such, time in the concept that we are used to use it is not existent: clocks are not measuring time per se.

Time is the highest form of energy represented by spin, charge and oscillation.

There is NO preserved state of the past, future is a probability distribution of a sample space, not defined. Given some ceteris paribus assumptions and blending out specific relativistic effects: there is no past at all, the covariance of time in view to motion is related to the photon as a state of space at C.

Wormholes, in case they exist, cannot be configurated to a specific polarization and state of the photon for a given locality, but wormholes refer also to a state of space in view of c or FTL, the same principle. You cannot measure the "past" and attribute a preserved past state, but for a time travel process, you would need to do that.

There is no time travel at all, except being able to change the state of space itself with all its properties!

String Theory.................Particle Physics

(Phys.org) —Scientists at Towson University in Towson, Maryland, have identified a practical, yet overlooked, test of string theory based on the motions of planets, moons and asteroids, reminiscent of Galileo's famed test of gravity by dropping balls from the Tower of Pisa.

String theory is infamous as an eloquent theoretical framework to understand all forces in the universe —- a so-called "theory of everything" —- that can't be tested with current instrumentation because the energy level and size scale to see the effects of string theory are too extreme.

Yet inspired by Galileo Galilei and Isaac Newton, Towson University scientists say that precise measurements of the positions of solar-system bodies could reveal very slight discrepancies in what is predicted by the theory of general relativity and the equivalence principle, or establish new upper limits for measuring the effects of string theory.

The Towson-based team presents its finding today, January 6, 2014, between 10 a.m. and 11:30 a.m., at the 223rd meeting of the American Astronomical Society, in Washington, D.C. The work also appears in the journal Classical and Quantum Gravity.

String theory hopes to provide a bridge between two well-tested yet incompatible theories that describe all known physics: Einstein's general relativity, our reigning theory of gravity; and the standard model of particle physics, or quantum field theory, which explains all the forces other than gravity.

String theory posits that all matter and energy in the universe is composed of one-dimensional strings. These strings are thought to be a quintillion times smaller than the already infinitesimal hydrogen atom and thus too minute to detect indirectly. Similarly, finding signs of strings in a particle accelerator would require millions of times more energy than what has been needed to identify the famous Higgs boson.

"Scientists have joked about how string theory is promising...and always will be promising, for the lack of being able to test it," said Dr. James Overduin of the Department of Physics, Astronomy and Geosciences at Towson University, first author on the paper. "What we have identified is a straightforward method to detect cracks in general relativity that could be explained by string theory, with almost no strings attached."

Read more at: http://phys.org/news/2014-01-scientists-theory.html#jCp

New model shows light can be captured in a Bose-Einstein condensate state

New model shows light can be captured in a Bose-Einstein condensate state.

This research was published in Physical Review A (http://journals.aps.org/pra/abstract/10.1103/PhysRevA.89.033862).

If anybody wants to read the paper then here's the link: http://arxiv.org/abs/1401.0520

New State Of Light Offered Up By Physicist Overseas

www.huffingtonpost.com

A theoretical physicist has explained a way to capture particles of light called photons, even at room temperature, a feat thought only possible at bone-chillingly cold temperatures. Alex Kruchkov, a doctoral student at the Swiss Federal Institute...

Does Light Experience Time?

Does Light Experience Time? http://buff.ly/Ro93La

Does Light Experience Time?

www.universetoday.com

Have you ever noticed that time flies when you're having fun? Well, not for light. In fact, photons don't experience any time at all. Here's a mind-bending concept that should shatter your brain into...

Quantum near-horizon geometry of a black 0-brane

Quantum near-horizon geometry of a black 0-brane (3 photos)

Artist's rendering of the interior of a black hole as a collection of strings. http://legacy.kek.jp/intra-e/press/2008/BlackHole_e.html

Physicists are scratching their heads...

Physicists are scratching their heads...

Neutron Death Mystery Stymies Physicists

www.huffingtonpost.com

Despite decades of taking measurements, scientists cannot agree on how long neutrons live. Neutrons are stable inside atoms, but on their own they decay in about...

visualizing complex electronic state

The new findings are reported this week in the journal Nature Materials, in a paper by MIT postdoc Xin Li, professors Young Lee and Gerbrand Ceder, also of MIT, and 12 others.

Team visualizes complex electronic state

newsoffice.mit.edu

Multidisciplinary group solves mystery of how a potential battery electrode material behaves.

Observation of geometric scaling of Efimov states in a Fermi-Bose Li-Cs mixture

Observation of geometric scaling of Efimov states in a Fermi-Bose Li-Cs mixture

Shih-Kuang Tung, Karina Jimenez-Garcia, Jacob Johansen, Colin V. Parker, Cheng Chin

(Submitted on 24 Feb 2014)

The emergence of scaling symmetry in physical phenomena suggests a universal description that is insensitive to microscopic details. A well known example is critical phenomena, which are invariant under continuous scale transformations and classify second-order phase transitions into distinct universality classes. Equally intriguing are systems with discrete scaling symmetry, which are invariant under scaling transformation with a specific scaling constant, resulting in log-periodic behavior in the observables. A classic example is the self-similar growth of crystals, as in snowflakes. In few-body physics, Vitaly Efimov predicted in 1970 the existence of an infinite series of three-body bound states that obey universal discrete scaling symmetry when pair-wise interactions are resonantly enhanced. Despite abundant reports of Efimov states in cold atom experiments, direct observation of discrete scaling symmetry remains an elusive goal. Here we report the observation of three Efimov resonances in a heteronuclear Li-Cs mixture near a broad interspecies Feshbach resonance. The positions of the resonances provide a model-independent confirmation of discrete scaling symmetry with an averaged scaling constant λexp=4.85(44), in good agreement with the predicted value of 4.88. Our findings also provide new insight into the possible discrete scaling symmetry in Bose gasses and mixtures with resonant interactions.

http://arxiv.org/abs/1402.5943

Question

Gravity is the force that is constantly working to centralize quantum harmonic oscillators into the unified field. Black holes disappear once oscillators are centralized into the unified field by its gravity. What do you say?