Se presenta una introducción a los fundamentos de la Relatividad General y la noción de Agujeros Negros de una manera elemental, asumiendo conocimientos básicos de Física, y relegando a notas al pie de página aquellas acotaciones técnicas que requieran mayores conocimientos. Se da además una breve introdución histórica del concepto de agujero negro, y se mencionan los notables avances recientes en el campo experimental: la detección en 2015 de ondas gravitacionales en LIGO y las imágenes obtenidas por el Event Horizon Telescope.
In Italy, INFN coordinates the research in the field of astro-particle physics. The supported experimental activities include the study of the cosmic radiation, the search of gravitational waves, the study of dark universe, general and quantum physics, and the study of the neutrino properties. A rich program of experiments installed on the earth, in the space, and underground or underwater is being supported to provide a possible answer to some of the most relevant open questions of particle physics, astrophysics, and cosmology. A short overview of the ongoing effort is presented.
Neste artigo, iremos revisar, de maneira não técnica, conceitos chaves para o entendimento do que são ondas gravitacionais. Com intuito de abarcar um amplo público, vamos discutir o que são ondas sonoras, ondas eletromagnéticas, a natureza da gravitação e ondas gravitacionais propriamente ditas. Abordaremos também alguns aspectos da detecção da primeira onda gravitacional e as consequências dessa grande conquista para a ciência e nosso conhecimento sobre o universo.
John A. Seed, Helen R. Sharpe, Harry J. Futcher
et al.
AbstractTreatment of [Ph3EMe][I] with [Na{N(SiMe3)2}] affords the ylides [Ph3E=CH2] (E=As, 1As; P, 1P). For 1As this overcomes prior difficulties in the synthesis of this classical arsonium‐ylide that have historically impeded its wider study. The structure of 1As has now been determined, 45 years after it was first convincingly isolated, and compared to 1P, confirming the long‐proposed hypothesis of increasing pyramidalisation of the ylide‐carbon, highlighting the increasing dominance of E+−C− dipolar resonance form (sp3‐C) over the E=C ene π‐bonded form (sp2‐C), as group 15 is descended. The uranium(IV)–cyclometallate complex [U{N(CH2CH2NSiPri3)2(CH2CH2SiPri2CH(Me)CH2)}] reacts with 1As and 1P by α‐proton abstraction to give [U(TrenTIPS)(CHEPh3)] (TrenTIPS=N(CH2CH2NSiPri3)3; E=As, 2As; P, 2P), where 2As is an unprecedented structurally characterised arsonium‐carbene complex. The short U−C distances and obtuse U‐C‐E angles suggest significant U=C double bond character. A shorter U−C distance is found for 2As than 2P, consistent with increased uranium‐ and reduced pnictonium‐stabilisation of the carbene as group 15 is descended, which is supported by quantum chemical calculations.
Dalam kasus ini saya akan membahas tentang persoalan Etika. Kasus ini terjadi di Jakarta. seorang Ketua tim hukum Prabowo-Sandiaga Bambang Widjojanto diadukan ke perhimpunan Advokat Indonesia pimpinan fauzi Hasibuan di kantor peradilan, Jakarta Barat pada kamis (13-06-2019) laporan ini dilakukan oleh sekumpulan Aadvokat yang tergabung dalam Advokat indonesia Maju melaporkan Bambang Widjojanto (BW). Bambang Widjojanto diadukan untuk dua persoalan Etika. Pertama, mantan pimpinan Komisi pemberantasan Korupsi (KPK) disebut melangar Etika saat menjadi kuasa hokum prabowo namun masih aktif sebagai pejabat Negara. Bambang Widjojanto diangap melangar Etika karena merendahkan MK tak hanya soal jabatannya sebagai ketua TGUPP, Bambang Widjojanto juga diadukakan untuk persoalan etika kedua kalinya ini terkait pernyataannya yang dinilai merendahkan Mahkamah konsitusi.Kasus ini sangat jelas melangar Etika. Secara umum dapat dikatakan bahwa etika adalah filsafat tentang tindakan manusia. suatu tindakan itu mempunyai nilai etis bila dilakukan oleh manusia. sangatlah jelas bahwa etika itu berurusan secara langsung dengan tindakan atau tingkah laku manusia. Tingkah laku manusia ini bukan tingkah laku yang tidak ada artinya.
Consider a flat sheet of paper - bending it slightly creates a smooth continuous shape. However, large, constrained deformations (e.g. crumpling) result in the emergence of localised features, in this case a network of creases. After opening the crumpled sheet, the presence and behaviour of the creases is critical to the deformation characteristics of the global sheet. Similarly, introducing cuts into a sheet can drastically affect its mechanical behaviour. For example, increasing stretchability or introducing out-of-plane buckling modes. Understanding the influence of local features, and concisely describing their mechanics, will enable better predictions of the collapse of thin-walled structures but also support the creation of innovative shape-changing devices. In this talk Martin will describe novel analysis techniques for localised features and their applications in the design of deployable structures and energy dissipating devices.Image credit: [Chinh Le Duc (Unsplash)](https://unsplash.com/photos/assorted-color-star-themed-decors-poK5c-QWy1E).