Fermions – it’s complicated

•August 17, 2017 • Leave a Comment

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“Using transport measurements near the field-tuned quantum critical point of CeRhIn5 at 50 Tesla, the researchers observed a fluctuating nematic-like state. A nematic state is most well known in liquid crystals, wherein the molecules of the liquid are parallel but not arranged in a periodic array. Nematic-like states have been observed in transition metal systems near magnetic and superconducting phase transitions. The occurrence of this property points to nematicity’s correlation with unconventional superconductivity. The difference, however, of the new nematic state found in CeRhIn5 relative to other systems is that it can be easily rotated by the magnetic field direction.”

Superconductivity research reveals potential new state of matter – phys.org

Spontaneous Order

•July 31, 2017 • Leave a Comment

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“The paper strips away the nitty-gritty details of cells and biology and describes a simpler, simulated system of chemicals in which it is nonetheless possible for exceptional structure to spontaneously arise—the phenomenon that England sees as the driving force behind the origin of life. ‘That doesn’t mean you’re guaranteed to acquire that structure,’ England explained. The dynamics of the system are too complicated and nonlinear to predict what will happen.

The simulation involved a soup of 25 chemicals that react with one another in myriad ways. Energy sources in the soup’s environment facilitate or ‘force’ some of these chemical reactions, just as sunlight triggers the production of ozone in the atmosphere and the chemical fuel ATP drives processes in the cell. Starting with random initial chemical concentrations, reaction rates and ‘forcing landscapes’—rules that dictate which reactions get a boost from outside forces and by how much—the simulated chemical reaction network evolves until it reaches its final, steady state, or ‘fixed point.'”

Controversial New Theory Suggests Life Wasn’t a Fluke of Biology: It Was Physics – Wired.com

“Testing 1-2-3… Is this thing on?”

•July 18, 2017 • Leave a Comment

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“The mystery has gripped the internet as speculation mounts about the potential for a discovery of alien life on the red dwarf star known as Ross 128—despite the best attempts of astronomers to put such rumors to rest.

‘In case you are wondering, the recurrent aliens hypothesis is at the bottom of many other better explanations,’ said a blog post by Abel Mendez, director of the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo.

Something unusual first came to light in April and May, when the team was studying a series of small and relatively cool red dwarf, some of which are known to have planets circling them.

Ross 128 is not known to have planets, but ‘we realized that there were some very peculiar signals in the 10-minute dynamic spectrum that we obtained from Ross 128.’

The signals were observed May 13 at 0053 GMT, and ‘consisted of broadband quasi-periodic non-polarized pulses with very strong dispersion-like features,’ he wrote.

‘We believe that the signals are not local radio frequency interferences (RFI) since they are unique to Ross 128 and observations of other stars immediately before and after did not show anything similar.'”

Peculiar’ radio signals emerge from nearby star – Phys.org

Retrocausality Revisited

•July 5, 2017 • Leave a Comment

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“If retrocausality is a feature of the quantum world, then it would have vast implications for physicists’ understanding of the foundations of quantum theory. Perhaps the biggest significance is the implication for the Bell tests, showing that distant particles really cannot influence each other, but rather—as Einstein and others believed—that quantum theory is incomplete. If the new results are true, then retrocausality may be one of the missing pieces that makes quantum theory complete.

‘I think that different interpretations [of quantum theory] have different implications for how we might go about generalizing standard quantum theory,’ Leifer said. ‘This might be needed to construct the correct theory of quantum gravity, or even to resolve some issues in high-energy physics given that the unification of the other three forces is still up in the air in the light of LHC results. So I think that future theories built on the ideas of existing interpretations are where we might see a difference, but admittedly we are quite far from figuring out how this might work at present.

‘Speculatively, if there is retrocausality in the universe, then it might be the case that there are certain eras, perhaps near the big bang, in which there is not a definite arrow of causality. You might imagine that a signature of such an era might show up in cosmological data, such as the cosmic microwave background. However, this is very speculative, and I have no idea what signatures we might expect yet.'”

Physicists provide support for retrocausal quantum theory, in which the future influences the past – Phys.org

Wanted: Large Litterbox

•May 10, 2017 • Leave a Comment

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“‘The idea of the experiment was proposed in 2003 by the group of Professor Timothy Ralph of the University of Queensland, Australia. In essence, we cause interference of two ‘cats’ on a beam splitter. This leads to an entangled state in the two output channels of that beam splitter. In one of these channels, a special detector is placed. In the event this detector shows a certain result, a ‘cat’ is born in the second output whose energy is more than twice that of the initial one.’

The Lvovsky group tested this method in the lab. In the experiment, they successfully converted a pair of negative squeezed ‘Schrodinger cats’ of amplitude 1.15 to a single positive ‘cat’ of amplitude 1.85. They generated several thousand such enlarged ‘cats’ in their experiment.”

Physicists breeding Schroedinger cat states – Phys.org

Challenging Time Translation Invariance

•May 5, 2017 • Leave a Comment

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“In this work, we show that quantum mechanical and gravitational properties of the clocks put fundamental limits to the joint measurability of time as given by clocks along nearby world lines. As a general feature, a quantum clock is a system in a superposition of energy eigenstates. Its precision, understood as the minimal time in which the state evolves into an orthogonal one, is inversely proportional to the energy difference between the eigenstates. Due to the mass–energy equivalence, gravitational effects arise from the energies corresponding to the state of the clock. These effects become nonnegligible in the limit of high precision of time measurement. In fact, each energy eigenstate of the clock corresponds to a different gravitational field. Because the clock runs in a superposition of energy eigenstates, the gravitational field in its vicinity, and therefore the space–time metric, is in a superposition. We prove that, as a consequence of this fact, the time dilation of clocks evolving along nearby world lines is ill-defined.We show that this effect is already present in the weak gravity and slow velocities limit, in which the number of particles is conserved. Moreover, the effect leads to entanglement between nearby clocks, implying that there are fundamental limitations to the measurability of time as recorded by the clocks.”

Entanglement of quantum clocks through gravity – PNAS

“Reality is merely an illusion, albeit a very persistent one.” – Einstein

•April 24, 2017 • 2 Comments

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“‘Philosophy and Predictive Processing’ focuses entirely on the influential theory in its title, which argues that our brains are constantly making predictions about what’s out there (a flower, a tiger, a person) and these predictions are what we perceive.

To make more accurate predictions, our brains modify their internal models of the world or force our bodies to move, so that the external environment comes in line with predictions. This idea unifies perception, action and cognition into a single framework.

Some of the titles of the papers are playful, and maybe a tad over-the-top: ‘How to entrain your evil demon’, ‘How to knit your own Markov blanket’ or ‘Of Bayes and Bullets’. But despite the titles, the content is serious and heavy-going: it’s written by some well-known proponents of predictive processing, including Andy Clark, based at the University of Edinburgh, UK, and Jakob Hohwy, at Monash University, Australia.”

A guide to why your world is a hallucination – New Scientist