# phys: cloud-to-ground lightning often strikes twice (or more)

<< Lightning is a dangerous yet poorly understood natural phenomenon. Lightning forms a network of plasma channels propagating away from the initiation point with both positively and negatively charged ends-called positive and negative leaders. >>

<< Negative leaders propagate in discrete steps, (..) Positive leaders propagate more continuously and thus emit very little high-frequency radiation. >>

<< It has been inferred that positive leaders can become transiently disconnected from negative leaders, which may lead to current pulses that both reconnect positive leaders to negative leaders, and cause multiple cloud-to-ground lightning events. >>

<< The disconnection process is thought to be due to negative differential resistance ... >>

AA << find small plasma structures-which (they) call 'needles'- (..) that appear to drain charge from the leader, and are probably the reason why positive leaders disconnect from negative ones, and why cloud-to-ground lightning connects to the ground multiple. >>

B. M. Hare, O. Scholten, et al. Needle-like structures discovered on positively charged lightning branches. Nature. volume 568, pages360–363 (2019) Apr 17, 2019.

https://www.nature.com/articles/s41586-019-1086-6

Why lightning often strikes twice. New study reveals needle-like structures in positively charged lightning leaders. Univ. of Groningen Apr 17, 2019

https://www.eurekalert.org/pub_releases/2019-04/uog-wlo041619.php

# tech: The U.S. Navy's patent for a "terrestrial UFO" (titled 'unconventional spacecraft propulsion systems')

<< A craft using an inertial mass reduction device comprises of an inner resonant cavity wall, an outer resonant cavity, and microwave emitters. The electrically charged outer resonant cavity wall and the electrically insulated inner resonant cavity wall form a resonant cavity. The microwave emitters create high frequency electromagnetic waves throughout the resonant cavity causing the resonant cavity to vibrate in an accelerated mode and create a local polarized vacuum outside the outer resonant cavity wall.
>>

Salvatore Cezar Pais. Craft using an inertial mass reduction device. - B64G1/409 Unconventional spacecraft propulsion systems. Current Assignee: US Secretary of Navy. US10144532B2. Dec 04, 2018.

https://patents.google.com/patent/US10144532B2/en

Nick Pope (@nickpopemod)

https://twitter.com/nickpopemod/status/1118969379629101056

Jasper Hamill. The US Navy has been granted a patent for an advanced aircraft which resembles a flying saucer UFO. Apr 18, 2019.

https://metro.co.uk/2019/04/18/us-navy-secretly-designed-super-fast-futuristic-aircraft-resembling-ufo-documents-reveal-9246755

Also

# esobio: #ufo, this phenomenon was a lot more than nuts and bolts machines ...  FonT. Jun 29, 2018

https://flashontrack.blogspot.com/2018/06/esobio-ufo-this-phenomenon-was-lot-more.html

# chem: HeH+, the beginning of chemistry

In the planetary nebula  NGC 7027 <<  SOFIA (Stratospheric Observatory for Infrared Astronomy) detected helium hydride, a combination of helium (..) and hydrogen (..), which was the first type of molecule to ever form in the early universe. This is the first time helium hydride has been found in the modern universe. >>

<< It was the beginning of chemistry, >> David Neufeld.

Marlowe Hood. Elusive molecule, first in Universe, detected in space. April 17, 2019.

https://m.phys.org/news/2019-04-elusive-molecule-universe-space.html 

Rolf Gusten, Helmut Wiesemeyer, et al. Astrophysical detection of the helium hydride ion HeH+. Nature, volume 568, pages 357–359 (2019)

https://www.nature.com/articles/s41586-019-1090-x  

# 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