Space inspires people


Four Eyes of Tatooine by Stefan Lines (created whilst working on his PhD thesis in Dr Leinhardt’s Planet Formation Group at the University of Bristol). This computer generated image, based on data taken from actual super-computer simulations, shows the formation of a planet around a binary star — a so called ‘circumbinary planet’. Tiny unit vectors show the magnitude (colour) and direction (orientation) of the acceleration of millions of tiny rocky ‘planetesimals’ that eventually coalesce to form a planet.

Why do you think space inspires people so much?

I guess that it’s our human nature to explore and we see it, at least most of us can see it, at night and I think that it’s in our nature to ask why things look the way they do, or why a process happens. And since you can look up in the sky and see a bunch of lights, it’s natural to question what that is and want to be able to explain it and go there. So I think it’s just our natural instinct to want to explain what we don’t understand, especially if we can see it.

(Zoë Leinhardtcontinue to read the interview)

Indefinite causality


Causality is a concept deeply rooted in our understanding of the world and lies at the basis of the very notion of time. It plays an essential role in our cognition — enabling us to make predictions, determine the causes of certain events, and choose the appropriate actions to achieve our goals. But even in quantum mechanics, for which countless measurements and preparations have been rethought, the assumption of pre-existing causal structure has never been challenged — until now.
Giulia Rubino and colleagues have designed an experiment to show that causal order can be genuinely indefinite. By creating wires between a pair of operating gates whose geometry is controlled by a quantum switch — the state of single photon — they realized a superposition of gate orders. From the output, they measured the so-called causal witness, which specifies whether a given process is causally ordered or not. The result brings a new set of questions to the fore — namely, where does causal order come from, and is it a necessary property of nature?

via Nature Physics (sci-hub)

Titan brighter at twilight than in daylight


Sketch showing the definition of phase angle

Muñoz, Antonio García, Panayotis Lavvas, and Robert A. West. “Titan brighter at twilight than in daylight.” Nature Astronomy 1, Article number: 0114 (2017) doi:10.1038/s41550-017-0114 (arXiv)

Investigating the overall brightness of planets (and moons) provides insights into their envelopes and energy budgets. Phase curves (a representation of the overall brightness versus the Sun–object–observer phase angle) for Titan have been published over a limited range of phase angles and spectral passbands. Such information has been key to the study of the stratification, microphysics and aggregate nature of Titan’s atmospheric haze and has complemented the spatially resolved observations showing that the haze scatters efficiently in the forward direction. Here, we present Cassini Imaging Science Subsystem whole-disk brightness measurements of Titan from ultraviolet to near-infrared wavelengths. The observations show that Titan’s twilight (loosely defined as the view at phase angles ≳150°) outshines its daylight at various wavelengths. From the match between measurements and models, we show that at even larger phase angles, the back-illuminated moon will appear much brighter than when fully illuminated. This behaviour is unique in our Solar System to Titan and is caused by its extended atmosphere and the efficient forward scattering of sunlight by its atmospheric haze. We infer a solar energy deposition rate (for a solar constant of 14.9 W m−2) of (2.84 ± 0.11) × 1014 W, consistent to within one to two standard deviations with Titan’s time-varying thermal emission from 2007 to 2013. We propose that a forward scattering signature may also occur at large phase angles in the brightness of exoplanets with extended hazy atmospheres and that this signature has a valuable diagnostic potential for atmospheric characterization.

Discotic Liquid Crystals with Graphene


Schematic illustration of columnar hexagonal arrangement of
discotic cores in 1-D semiconductor and charge migration.

Kumar, Manish, Ashwathanarayana Gowda, and Sandeep Kumar. “Discotic Liquid Crystals with Graphene: Supramolecular Self‐assembly to Applications.” Particle & Particle Systems Characterization (2017). doi:10.1002/ppsc.201700003 (sci-hub)

In past decades many breakthroughs have been witnessed in research on liquid crystals (LCs) and the application of LCs has spread. On another side graphene is considered as a rapidly rising star on the horizon of materials science, soft condensed matter physics and promising applications. Supramolecular chemistry of LCs and graphene together is described as “chemistry beyond the molecule”. A new class of 2D colloidal graphene oxide liquid crystalline material consisting discotic liquid crystallinity and their interactions with LCs present a platform for number of versatile properties and applications. This review focuses on discotic liquid crystalline (DLC) behavior of graphene oxide/reduced graphene oxide in various solvents, their characterization and application for energy storage, wet-spinning fibers, electro-optical devices, and displays etc. In the first part of this review, a brief introduction of discotic graphene oxide liquid crystals (GOLCs), their fundamental, synthesis process, supramolecular structures of graphene-DLC composites is highlighted. In the second part, some important physical studies and application of this largest polycyclic aromatic core of DLCs are discussed. Finally, an outlook on this emerging two dimensional material in liquid crystal field with relevant scientific application background is presented.

Creative mathematical tasks contribute to deeper learning in mathematics


Press Release

Mathias Norqvist

Mathias Norqvist

Working with creative mathematical tasks is important for pupils both to reflect on mathematics as well as for their subsequent test results. Being faced with creative tasks during exercise has evident effects on all pupils, both on weak and high performers. This according to studies at Umeå University in Sweden.
“The results of my dissertation show the importance for pupils to work with creative reasoning and not always get methods and rules presented in advance. This is something both publishers and teachers could take into account more often when designing mathematical tasks,” says Mathias Norqvist, doctoral student at the Department of Mathematics and Mathematical Statistics at Umeå University.
The studies show that pupils at upper secondary school who work with exercises designed to encourage creative mathematical reasoning more easily remember what they have learnt and, as a result, perform better.
“Contrary to common belief, it seems to be the low performing pupils who benefit most from practicing with creative tasks, in comparison to more imitative tasks where focus lies on how to use the given solutions,” says Mathias Norqvist.
There is a great risk that pupils who are presented one method, will use it without further reflection. Although, there are of course certain methods in mathematics that should be automated to relieve the pressure on the working memory, but it should not come at a cost to the understanding of the underlying mathematics. Since well-designed creative exercises can focus on central mathematical properties, they are important for all pupils since they force pupils to reflect on the mathematics and to base their reasoning on what they already know.
A total of about 300 upper secondary school pupils participated in the studies that formed the basis of the dissertation.