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Bringing quantum mechanics to life: from Schrödinger’s cat to Schrödinger’s microbe

Zhang-qi Yin, Tongcang Li
The question whether quantum mechanics is complete and the nature of the transition between quantum mechanics and classical mechanics have intrigued physicists for decades. There have been many experimental breakthroughs in creating larger and larger quantum superposition and entangled states since Erwin Schr\”{o}dinger proposed his famous thought experiment of putting a cat in a superposition of both alive and dead states in 1935. Remarkably, recent developments in quantum optomechanics and electromechanics may lead to the realization of quantum superposition of living microbes soon. Recent evidences also suggest that quantum coherence may play an important role in several biological processes. In this review, we first give a brief introduction to basic concepts in quantum mechanics and the Schr\”{o}dinger’s cat thought experiment. We then review developments in creating quantum superposition and entangled states and the realization of quantum teleportation. Non-trivial quantum effects in photosynthetic light harvesting and avian magnetoreception are also discussed. At last, we review recent proposals to realize quantum superposition, entanglement and state teleportation of microorganisms, such as viruses and bacteria.
Read more at http://arxiv.org/pdf/1608.05322v1.pdf

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How supernovae became the basis of observational cosmology

Supernova classification

Supernova classification

Maria Victorovna Pruzhinskaya, Sergey Mikhailovich Lisakov
This paper is dedicated to the discovery of one of the most important relationships in supernova cosmology – the relation between the peak luminosity of Type Ia supernovae and their luminosity decline rate after maximum light.
The history of this relationship is quite long and interesting. The relationship was independently discovered by the American statistician and astronomer Bert Woodard Rust and the Soviet astronomer Yury Pavlovich Pskovskii in the 1970s.
Using a limited sample of Type I supernovae they were able to show that the brighter the supernova is, the slower its luminosity declines after maximum.
Only with the appearance of CCD cameras could Mark Phillips re-inspect this relationship on a new level of accuracy using a better sample of supernovae. His investigations confirmed the idea proposed earlier by Rust and Pskovskii.
Read more at https://arxiv.org/ftp/arxiv/papers/1608/1608.04192.pdf

KIC 8462852 Faded Throughout the Kepler Mission

Over the four years that the Kepler telescope monitored this mysterious star, its light levels dropped by a total of about 3 percent--but not all at a constant rate. (For reference, the huge dip at the 800 mark is one of the huge dips that originally tipped off scientists that this was a freakin' weird star. "It was off the charts," says Montet.)

Over the four years that the Kepler telescope monitored this mysterious star, its light levels dropped by a total of about 3 percent–but not all at a constant rate. (For reference, the huge dip at the 800 mark is one of the huge dips that originally tipped off scientists that this was a freakin’ weird star. “It was off the charts,” says Montet.)

Benjamin T. Montet, Joshua D. Simon
KIC 8462852 is a superficially ordinary main sequence F star for which Kepler detected an unusual series of brief dimming events. We obtain accurate relative photometry of KIC 8462852 from the Kepler full frame images, finding that the brightness of KIC 8462852 monotonically decreased over the four years it was observed by Kepler. Over the first ~1000 days, KIC 8462852 faded approximately linearly at a rate of 0.341 +/- 0.041 percent per year, for a total decline of 0.9%. KIC 8462852 then dimmed much more rapidly in the next ~200 days, with its flux dropping by more than 2%. For the final ~200 days of Kepler photometry the magnitude remained approximately constant, although the data are also consistent with the decline rate measured for the first 2.7 yr. Of a sample of 193 nearby comparison stars and 355 stars with similar stellar parameters, 0.6% change brightness at a rate as fast as 0.341 +/- 0.041 percent per year, and none exhibit either the rapid decline by >2% or the cumulative fading by 3% of KIC 8462852. We examine whether the rapid decline could be caused by a cloud of transiting circumstellar material, finding while such a cloud could evade detection in sub-mm observations, the transit ingress and duration cannot be explained by a simple cloud model. Moreover, this model cannot account for the observed longer-term dimming. No known or proposed stellar phenomena can fully explain all aspects of the observed light curve.

Read more at https://arxiv.org/pdf/1608.01316v1.pdf
Read also: SCIENTISTS IN THE DARK OVER YEARS-LONG DIMMING OF ‘ALIEN MEGASTRUCTURE STAR’

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“What’s (the) Matter?”

A Show on Elementary Particle Physics with 28 Demonstration Experiments
Herbi K. Dreiner et al
We present the screenplay of a physics show on particle physics, by the Physikshow of Bonn University. The show is addressed at non-physicists aged 14+ and communicates basic concepts of elementary particle physics including the discovery of the Higgs boson in an entertaining fashion. It is also demonstrates a successful outreach activity heavily relying on the university physics students. This paper is addressed at anybody interested in particle physics and/or show physics. This paper is also addressed at fellow physicists working in outreach, maybe the experiments and our choice of simple explanations will be helpful. Furthermore, we are very interested in related activities elsewhere, in particular also demonstration experiments relevant to particle physics, as often little of this work is published.
Our show involves 28 live demonstration experiments. These are presented in an extensive appendix, including photos and technical details. The show is set up as a quest, where 2 students from Bonn with the aid of a caretaker travel back in time to understand the fundamental nature of matter. They visit Rutherford and Geiger in Manchester around 1911, who recount their famous experiment on the nucleus and show how particle detectors work. They travel forward in time to meet Lawrence at Berkeley around 1950, teaching them about the how and why of accelerators. Next, they visit Wu at DESY, Hamburg, around 1980, who explains the strong force. They end up in the LHC tunnel at CERN, Geneva, Switzerland in 2012. Two experimentalists tell them about colliders and our heroes watch live as the Higgs boson is produced and decays. The show was presented in English at Oxford University and University College London, as well as Padua University and ICTP Trieste. It was 1st performed in German at the Deutsche Museum, Bonn (5/’14). The show has eleven speaking parts and involves in total 20 people.
Read more at http://arxiv.org/pdf/1607.07478v1.pdf

Leonardo da Vinci’s studies of friction

Sketches from two different pages in Leonardo’s notebooks: (a, b) from Codex Atlanticus, Biblioteca Ambrosiana, Milan (CA folio 532r c. 1506-8), and (c) from Codex Arundel, British Library, London (Arundel folio 41r c. 1500-05)

Sketches from two different pages in Leonardo’s notebooks: (a, b) from Codex
Atlanticus, Biblioteca Ambrosiana, Milan (CA folio 532r c. 1506-8), and (c) from Codex Arundel, British Library, London (Arundel folio 41r c. 1500-05)

Ian M. Hutchings
Based on a detailed study of Leonardo da Vinci’s notebooks, this review examines the development of his understanding of the laws of friction and their application. His work on friction originated in studies of the rotational resistance of axles and the mechanics of screw threads.
He pursued the topic for more than 20 years, incorporating his empirical knowledge of friction into models for several mechanical systems. Diagrams which have been assumed to represent his experimental apparatus are misleading, but his work was undoubtedly based on experimental measurements and probably largely involved lubricated contacts.
Although his work had no influence on the development of the subject over the succeeding centuries, Leonardo da Vinci holds a unique position as a pioneer in tribology.
Read more at http://www.ifm.eng.cam.ac.uk/uploads/Hutchings_Leonardo_Friction_2016_v2.pdf

Read also: Study reveals Leonardo da Vinci’s ‘irrelevant’ scribbles mark the spot where he first recorded the laws of friction