# chem: it can stay squishy at the coldest temperatures

<< Normal materials become brittle in deep cryogenic conditions, but a new graphene-based foam (..) stays as flexible as ever. >>

Maria Temming. A new graphene foam stays squishy at the coldest temperatures. Apr 12, 2019.

https://www.sciencenews.org/article/new-graphene-foam-squishy-coldest-temperatures

AA << report wide temperature–invariant large-strain super-elastic behavior in three-dimensionally cross-linked graphene materials that persists even to a liquid helium temperature of 4 K, a property not previously observed for any other material. >>

Kai Zhao, Tengfei Zhang, et al. Super-elasticity of three-dimensionally cross-linked graphene materials all the way to deep cryogenic temperatures. Science Advances  12 Apr 2019: Vol. 5, no. 4, eaav2589. doi: 10.1126/sciadv.aav2589

https://advances.sciencemag.org/content/5/4/eaav2589

# evol: the origins of life on earth could be arisen from the same set of DNA and RNA precursor molecules

<< the first living things on Earth may have used both RNA (ribonucleic acid) and DNA (deoxyribonucleic acid), as all cell-based life forms do now. In contrast, the prevailing scientific view—the "RNA World" hypothesis—is that early life forms were based purely on RNA, and only later evolved to make and use DNA. >>

<< These new findings suggest that it may not be reasonable for chemists to be so heavily guided by the RNA World hypothesis in investigating the origins of life on Earth, >>

Ramanarayanan Krishnamurthy. Building blocks of DNA and RNA could have appeared together before life began on Earth. The Scripps Research Institute. April 1, 2019.

https://m.phys.org/news/2019-04-blocks-dna-rna-life-began.html  

Jianfeng Xu, Nicholas J. Green, et al. Prebiotic phosphorylation of 2-thiouridine provides either nucleotides or DNA building blocks via photoreduction. Nature Chemistry. doi: 10.1038/s41557-019-0225-x April 1, 2019.

https://www.nature.com/articles/s41557-019-0225-x

# phys: a theoretical view on 'traversable wormholes'

<< wormholes can exist: tunnels in curved space-time, connecting two distant places, through which travel is possible. >>

<< It takes longer to get through these wormholes than to go directly, so they are not very useful for space travel,  (..)  From the outside perspective, travel through the wormhole is equivalent to quantum teleportation using entangled black holes, >> Daniel Jafferis.

Travel through wormholes is possible, but slow.  American Institute of Physics. Apr15, 2019.

https://m.phys.org/news/2019-04-wormholes.html  

Daniel L. Jafferis. Abstract: B02.00002 : Traversable wormholes.
11:21 AM–11:57 AM

http://meetings.aps.org/Meeting/APR19/Session/B02.2  

# gst: apropos of vanishing, strange behaviors, 'sometimes they are there, and then for very long periods of time, they are not.'

AA << report the discovery of two long-term intermittent radio pulsars in the ongoing Pulsar Arecibo L-Band Feed Array survey. >>

<<  PSRs J1910+0517 and J1929+1357 show long-term extreme bimodal intermittency, switching between active (ON) and inactive (OFF) emission states and indicating the presence of a large, hitherto unrecognized underlying population of such objects. >>

<< This is the first time that a significant evolution in the activity of an intermittent pulsar has been seen, and we show that the spin-down rate of the pulsar is proportional to the activity. >>

Lyne AG,  Stappers BW, et al. Two Long-Term Intermittent Pulsars Discovered in the PALFA Survey. The Astrophysical Journal, Volume 834, Issue 1, article id. 72, 9 pp. (2017).

http://adsabs.harvard.edu/abs/2017ApJ...834...72L

<< A new discovery has upended the widely held view that all pulsars are orderly ticking clocks of the universe. A survey done at the Arecibo Observatory in Puerto Rico has fortuitously discovered two extremely strange pulsars that undergo a "cosmic vanishing act." Sometimes they are there, and then for very long periods of time, they are not. >>

The Mystery of Part Time Pulsars. Arecibo Observatory. Jul 18, 2017.

https://www.naic.edu/ao/blog/mystery-part-time-pulsars

# phys: apropos of "Wigner’s Friend" paradox, now tested in a real experiment ...

<< Back in 1961, the Nobel Prize–winning physicist Eugene Wigner outlined a thought experiment that demonstrated one of the lesser-known paradoxes of quantum mechanics. The experiment shows how the strange nature of the universe allows two observers-say, Wigner and Wigner’s friend-to experience different realities. >>

<< Last year, (..) physicists noticed that recent advances in quantum technologies have made it possible to reproduce the Wigner’s Friend test in a real experiment. In other words, it ought to be possible to create different realities and compare them in the lab to find out whether they can be reconciled. >>

A quantum experiment suggests there’s no such thing as objective reality. Emerging Technology from the arXiv.  Mar 12, 2019.

https://www.technologyreview.com/s/613092/a-quantum-experiment-suggests-theres-no-such-thing-as-objective-reality/

https://twitter.com/techreview/status/1116923783183519744

Massimiliano Proietti, Alexander Pickston, et al. Experimental rejection of observer-independence in the quantum world.  arXiv:1902.05080  Feb 13, 2019.

https://arxiv.org/abs/1902.05080

Also

Ryunosuke Akutagawa, Rashomon (1915)

https://it.m.wikipedia.org/wiki/Ry%C5%ABnosuke_Akutagawa

https://it.m.wikipedia.org/wiki/Rashomon

# phys: to characterize the tiny fluctuations in the vacuum, in detail

<< In quantum physics, a vacuum is not empty, but rather steeped in tiny fluctuations of the electromagnetic field. Until recently it was impossible to study those vacuum fluctuations directly. Researchers at ETH Zurich have developed a method that allows them to characterize the fluctuations in detail. >>

Oliver Morsch. Fluc­tu­a­tions in the void. ETH Zurich. Apr 11, 2019.

https://m.phys.org/news/2019-04-fluctuations-void.html

<< A direct method of determining the spectral characteristics of vacuum field fluctuations has so far been missing. >>

AA << perform a direct measurement of the field correlation on these fluctuations in the terahertz frequency range by using electro-optic detection  in a nonlinear crystal placed in a cryogenic environment  >>

Ileana-Cristina Benea-Chelmus, Francesca Fabiana Settembrini, et al.
Electric field correlation measurements on the electromagnetic vacuum state. Nature. volume 568, pages202–206 (2019) Apr 10.

https://www.nature.com/articles/s41586-019-1083-9

# brain: Simulating the decision-making process of a partner monkey

<< Primates observe the choices of social partners to learn about the reward value of objects. Such values learned from observation not only inform own decision-making but may also provide a basis for understanding the decisions of others. (..) These cognitive processes-learning from others and predicting their choices-are critical foundations for primates' sophisticated social behavior.  >>

AA << show that monkeys' amygdala neurons derive object values from observation and use these values to simulate a partner monkey’s decision process. >>

Fabian Grabenhorst, Raymundo Báez-Mendoza, et al.  Primate Amygdala Neurons Simulate Decision Processes of Social Partners.  Apr 11, 2019. doi: 10.1016/j.cell.2019.02.042.

https://www.cell.com/cell/fulltext/S0092-8674(19)30225-9

'Mindreading' neurons simulate decisions of social partners. University of Cambridge.  Apr 11, 2019.

https://m.medicalxpress.com/news/2019-04-mindreading-neurons-simulate-decisions-social.html