Is There a 5th Nuclear Force?

In a new paper, University of California, Riverside theoretical physicist Flip Tanedo and his collaborators have made new progress towards unravelling a mystery in the beryllium nucleus that may be evidence for a fifth force of nature.

Earlier this year, an experiment in Hungary reported very unusual behavior in the decays of beryllium-8 nuclei. The experimental collaboration suggested that their results may come from the effects of a new force of nature.

If confirmed, this would have far-reaching consequences on fundamental physics including grand unification, dark matter and the experimental strategy for pushing the frontier of human knowledge.

Intrigued, Tanedo, an assistant professor at UC Riverside, and his collaborators - all theoretical physicists - decided to investigate further.

In an paper posted earlier this year, the team did the first theoretical analysis of the Hungarian team's interpretation, and showed how usual assumptions of how a fifth force would behave don't seem to work in this case because of the high energy physics experiments that would otherwise rule it out. This represented the first steps to finding wiggle room for what it would take for the fifth force interpretation to work.

link.

Extraordinary Claim: How to Detect Dark Matter...From the Earth's Core

Dark Photons from the Center of the Earth: Smoking-Gun Signals of Dark Matter

Authors:

Feng et al

Abstract:

Dark matter may be charged under dark electromagnetism with a dark photon that kinetically mixes with the Standard Model photon. In this framework, dark matter will collect at the center of the Earth and annihilate into dark photons, which may reach the surface of the Earth and decay into observable particles. We determine the resulting signal rates, including Sommerfeld enhancements, which play an important role in bringing the Earth's dark matter population to their maximal, equilibrium value. For dark matter masses mX∼ 100 GeV - 10 TeV, dark photon masses mA′∼ MeV - GeV, and kinetic mixing parameters ε∼10−9−10−7, the resulting electrons, muons, photons, and hadrons that point back to the center of the Earth are a smoking-gun signal of dark matter that may be detected by a variety of experiments, including neutrino telescopes, such as IceCube, and space-based cosmic ray detectors, such as Fermi-LAT and AMS. We determine the signal rates and characteristics, and show that large and striking signals---such as parallel muon tracks---are possible in regions of the (mA′,ε) plane that are not probed by direct detection, accelerator experiments, or astrophysical observations.

Could Quantum Entanglement Increase a Particle's "Mass"

 [O]ne theorist has shown that an exotic quantum effect called entanglement has a real and measurable influence on a gravitational field— the first time this kind of link has ever been shown.

David Bruschi at the Hebrew University of Jerusalem in Israel says the new result has important implications for quantum mechanics and relativity and may represent an important step towards a long sought after theory that explains them both.

Bruschi’s idea is simple in principle. Physicists have long known that a single quantum particle can exist in two places at the same time. There is a clear quantum correlation called entanglement between these two locations that is well-defined mathematically in quantum mechanics.

Bruschi’s new approach is to formulate the mathematics in the context of relativity. He first makes the mathematical assumption that some perturbation of a gravitational field is possible in these circumstances.

He then goes on to formulate the mathematical properties of this perturbation and how they evolve when the two locations are maximally entangled and when they are not, a state known as maximally mixed.

He finds that the perturbation is zero when the states are maximally mixed. But in the other case— when the two locations are maximally entangled— the perturbation spreads through space over a scale related to the energy of the particle and the coherence time of the entanglement.

This kind of perturbation is mathematically similar to a gravitational wave, albeit on a much smaller scale. It is essentially equivalent to the particle having some additional weight. And that is what makes it potentially detectable.

link.

Beyond Extraordinary Claim: Gravitational Constant is Variable (& its a solution to the faint sun paradox!)

Can a variable gravitational constant resolve the Faint Young Sun Paradox ?

Authors:

Sahni et al

Abstract:

Solar models suggest that four billion years ago the young Sun was about 75% fainter than it is today, rendering Earth's oceans frozen and lifeless. However, there is ample geophysical evidence that Earth had a liquid ocean teeming with life 4 Gyr ago. Since L⊙∝G7M5⊙, the Sun's luminosity L⊙ is exceedingly sensitive to small changes in the gravitational constant G. We show that a percent-level increase in G in the past would have prevented Earth's oceans from freezing, resolving the faint young Sun paradox. Such small changes in G are consistent with observational bounds on ΔG/G. Since LSNIa∝G−3/2, an increase in G leads to fainter supernovae, creating tension between standard candle and standard ruler probes of dark energy. Precisely such a tension has recently been reported by the Planck team.

Physicists Discover Method to Create Matter From Light

Imperial College London physicists have discovered how to create matter from light - a feat thought impossible when the idea was first theorised 80 years ago.

In just one day over several cups of coffee in a tiny office in Imperial's Blackett Physics Laboratory, three physicists worked out a relatively simple way to physically prove a theory first devised by scientists Breit and Wheeler in 1934.

Breit and Wheeler suggested that it should be possible to turn light into matter by smashing together only two particles of light (photons), to create an electron and a positron – the simplest method of turning light into matter ever predicted. The calculation was found to be theoretically sound but Breit and Wheeler said that they never expected anybody to physically demonstrate their prediction. It has never been observed in the laboratory and past experiments to test it have required the addition of massive high-energy particles.

The new research, published in Nature Photonics, shows for the first time how Breit and Wheeler's theory could be proven in practice. This 'photon-photon collider', which would convert light directly into matter using technology that is already available, would be a new type of high-energy physics experiment. This experiment would recreate a process that was important in the first 100 seconds of the universe and that is also seen in gamma ray bursts, which are the biggest explosions in the universe and one of physics' greatest unsolved mysteries.

The scientists had been investigating unrelated problems in fusion energy when they realised what they were working on could be applied to the Breit-Wheeler theory. The breakthrough was achieved in collaboration with a fellow theoretical physicist from the Max Planck Institute for Nuclear Physics, who happened to be visiting Imperial.

link.

Weirdness of Singularities: Hawking's Attempt at Trying to Avoid the Firewall

Information Preservation and Weather Forecasting for Black Holes

Author:

Hawking

Abstract:

It has been suggested [1] that the resolution of the information paradox for evaporating black holes is that the holes are surrounded by firewalls, bolts of outgoing radiation that would destroy any infalling observer. Such firewalls would break the CPT invariance of quantum gravity and seem to be ruled out on other grounds. A different resolution of the paradox is proposed, namely that gravitational collapse produces apparent horizons but no event horizons behind which information is lost. This proposal is supported by ADS-CFT and is the only resolution of the paradox compatible with CPT. The collapse to form a black hole will in general be chaotic and the dual CFT on the boundary of ADS will be turbulent. Thus, like weather forecasting on Earth, information will effectively be lost, although there would be no loss of unitarity.

Snowmass Results: Planning the Future of U.S. Particle Physics

Snowmass meeting on planning the future of United States efforts in particle physics.

Reports.

1. Summary.
2. Intensity Frontier. 
3. Energy Frontier 
4. Cosmic Frontier

There will be more as I understand it.

Extraordinary Claim: A Stable Wormhole Compatible With General Relativity

Example of a stable wormhole in general relativity

Authors:

Bronnikov et al

Abstract:

We study a static, spherically symmetric wormhole model whose metric coincides with that of the so-called Ellis wormhole but the material source of gravity consists of a perfect fluid with negative density and a source-free radial electric or magnetic field. For a certain class of fluid equations of state, it has been shown that this wormhole model is linearly stable under both spherically symmetric perturbations and axial perturbations of arbitrary multipolarity. A similar behavior is predicted for polar nonspherical perturbations. It thus seems to be the first example of a stable wormhole model in the framework of general relativity (at least without invoking phantom thin shells as wormhole sources).

The Surprise of the Higgs Boson is There are NO Surprises

Is Time an Artifact of Being the Restricted Observer?

Time is an emergent phenomenon that is a side effect of quantum entanglement, say physicists. And they have the first exprimental results to prove it

When the new ideas of quantum mechanics spread through science like wildfire in the first half of the 20th century, one of the first things physicists did was to apply them to gravity and general relativity. The result were not pretty.

It immediately became clear that these two foundations of modern physics were entirely incompatible. When physicists attempted to meld the approaches, the resulting equations were bedeviled with infinities making it impossible to make sense of the results.

Then in the mid-1960s, there was a breakthrough. The physicists John Wheeler and Bryce DeWitt successfully combined the previously incompatible ideas in a key result that has since become known as the Wheeler-DeWitt equation. This is important because it avoids the troublesome infinites—a huge advance.

But it didn’t take physicists long to realise that while the Wheeler-DeWitt equation solved one significant problem, it introduced another. The new problem was that time played no role in this equation. In effect, it says that nothing ever happens in the universe, a prediction that is clearly at odds with the observational evidence.

This conundrum, which physicists call ‘the problem of time’, has proved to be thorn in flesh of modern physicists, who have tried to ignore it but with little success.

Then in 1983, the theorists Don Page and William Wooters came up with a novel solution based on the quantum phenomenon of entanglement. This is the exotic property in which two quantum particles share the same existence, even though they are physically separated.

Entanglement is a deep and powerful link and Page and Wooters showed how it can be used to measure time. Their idea was that the way a pair of entangled particles evolve is a kind of clock that can be used to measure change.

But the results depend on how the observation is made. One way to do this is to compare the change in the entangled particles with an external clock that is entirely independent of the universe. This is equivalent to god-like observer outside the universe measuring the evolution of the particles using an external clock.

In this case, Page and Wooters showed that the particles would appear entirely unchanging—that time would not exist in this scenario.

But there is another way to do it that gives a different result. This is for an observer inside the universe to compare the evolution of the particles with the rest of the universe. In this case, the internal observer would see a change and this difference in the evolution of entangled particles compared with everything else is an important a measure of time.

This is an elegant and powerful idea. It suggests that time is an emergent phenomenon that comes about because of the nature of entanglement. And it exists only for observers inside the universe. Any god-like observer outside sees a static, unchanging universe, just as the Wheeler-DeWitt equations predict.

link.  paper link.

So, someone who is outside the universe, all observing, doesn't see squat.  um.  theological problem, maybe?

Blackhole Firewalls an Exciting Conumdrum for Physics

“The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘eureka!’ but ‘that's funny,’” Isaac Asimov once said. Well, something seriously funny is going on in theoretical physics these days. A recent conundrum about black holes is threatening to overturn some of the most basic tenets of physics, and many scientists are nothing but thrilled.

“To me it’s the best thing that’s happened in awhile,” says University of California, Berkeley, physicist Raphael Bousso of the so-called “black hole firewall paradox,” which concerns what happens at the boundary of a black hole. “This is a 9 on the Richter earthquake scale—it’s by far the most shocking and surprising thing that has happened in my career.” The quandary prompting such jubilation is an idea first put forward in July 2012, which was extended in a paper published October 21 in Physical Review Letters. Physicists have long assumed that space is smooth at a black hole’s event horizon—the point of no return where nothing that passes through can escape. A person crossing over that line shouldn’t immediately notice anything amiss, however, and neither should a distant observer watching that person. But physicists have also assumed that information can never be destroyed. The new work says those two ideas are mutually incompatible. “It’s a paradox because several things we believed were true can’t all be true,” says Joseph Polchinski of the Kavli Institute for Theoretical Physics and U.C. Santa Barbara, one of the main architects of the firewall idea.

Polchinski and his colleagues conclude that not only is space not smooth at a black hole horizon—at that point the laws of physics completely break down. Instead of an unobtrusive boundary, the scientists argue that there must actually be a sharp division they call a firewall. “The firewall is kind of a wall of energy—it could be the end of spacetime itself,” Polchinski says. “Anything hitting it would break up into its fundamental bits and effectively dissolve.” At first, many physicists strenuously objected to the bizarre idea of firewalls. “I tried very hard to get rid of them, but I don’t think it’s likely that will happen,” Bousso says. “I’ve decided that the most promising thing for me is to assume there are firewalls, and look into why they form.” Even the main authors of the idea aren’t completely onboard. “There is a group of people, including me half the time, that thinks there must be some subtle assumption that we’ve made that’s not valid,” Polchinski says. Yet he and everyone else admit they haven’t identified a flaw in the reasoning so far.

link.

Shtetl-Optimized Smack Down of the Pop Sci Write Ups of the

At first glance, the amplituhedron appears to be a way to calculate scattering amplitudes, in the planar limit of a certain mathematically-interesting (but, so far, physically-unrealistic) supersymmetric quantum field theory, more efficiently than by summing thousands of Feynman diagrams. In which case, you might say: “wow, this sounds like a genuinely-important advance for certain parts of mathematical physics! I’d love to understand it better. But, given the restricted class of theories it currently applies to, it does seem a bit premature to declare this a ‘jewel’ that unlocks all of physics, or a death-knell for spacetime, locality, and unitarity, etc. etc.”

Yet you’d be wrong: it isn’t premature at all. If anything, the popular articles have understated the revolutionary importance of the amplituhedron. And the reason I can tell you that with such certainty is that, for several years, my colleagues and I have been investigating a mathematical structure that contains the amplituhedron, yet is even richer and more remarkable. I call this structure the “unitarihedron.”

Go read.  OMG.  Go read.

Will Entanglement Violate Thermodynamics?

Thermodynamic Work Gain from Entanglement

Authors:

1. Ken Funo (a)

2. Yu Watanabe (b)

3. Masahito Ueda (a)

Institutions:

a. Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan

b. Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawa Oiwake-Cho, 606-8502 Kyoto, Japan

Abstract:

We show that entangled states can be used to extract thermodynamic work beyond classical correlation via feedback control based on measurement on part of a composite system. The work gain is determined by the amount of correlation that is transfered from between the subsystems to between the system and the memory. Furthermore, entangled states require less measurement cost because we can perform feedback control without decreasing the entropy of the system, and hence the memory does not need entropy production to compensate for the feedback gain.

Paper link.

Confirmation or refutation ought to be coming soon.  It'd be big if confirmed.  Somehow I have my doubts.