Earth

See that speck of dust? That's your home, Earth, as seen from Voyager. Think about that for a minute

The Fall and Rise of String Theory

The upcoming Evolved Laser Interferometer Space Antenna could help verify string theory's predictions of gravity waves. Three spacecraft will orbit around the sun and measure tiny ripples in space-time via sensitive lasers [credit: AEI/MM/EXOZET]. Inset: A 2D slice of the 6D Calabi-Yau quintic manifold. Andrew J. Hanson, Indiana University. [CC BY-SA 3.0 or Attribution], via Wikimedia Commons.

String theory was once the hottest thing in physics. In the 1980s and ’90s, it promised seemingly unlimited bounty. Arising from the notion that matter and energy are fundamentally composed of tiny, vibrating strings rather than pointlike particles, this theory attempted to unify all the known forces into a single, elegant package. Some physicists hailed string theory as the long-sought “theory of everything.”

Harvard University physicist Andrew Strominger, a leader in string theory for decades, remembers the early enthusiasm. "At the time of its new popularity," he says, "there was a declaration that we had solved all the problems in physics and had the final theory in hand..."

(Read about the history of string theory and Prof. Strominger's engagement with it in: Steve Nadis, "The Fall and Rise of String Theory," Discover Magazine, June 14, 2016.)

 Harvard University Department of Physics

The origins of space and time

Many researchers believe that physics will not be complete until it can explain not just the behaviour of space and time, but where these entities come from

http://www.nature.com/news/theoretical-physics-the-origins-of-space-and-time-1.13613

Astro/Space IRANIAN PAINTING

• Title Iranian painting
• Released 29/07/2016 10:00 am
• Copyright Contains modified Copernicus Sentinel data (2016), processed by ESA
• Description

  The Sentinel-2A satellite takes us over to northeastern Iran, the second largest country in the Middle East.

  A dryland area, most of Iran’s territory is classified as arid and semi-arid, about half of which is characterised by rangeland, barren land and mountains.

  Visible in the centre of the image and at top left are alluvial fans. These are formed when streams or rivers hit plains and spread out. They represent the distinct pattern of water runoff from the mountains, where the eroded soil, with the help of rain, is carried from the mountain slopes to lower lands.

  At top left, resembling brush strokes in a painting, seasonal accumulation of water and various salt minerals is evident in greys and whites.

  Scattered throughout the image are many agricultural plots, distinct in such an arid and mountainous region, which also features various rocky formations.

  At the far right, the city of Bajestan is visible, with many agricultural fields around it. It is a city with a population of some 11 000, with saffron and pomegranate its most important products, grown in the various plots on the left.

  The shades of red indicate how sensitive the multispectral instrument on Sentinel-2A is to differences in chlorophyll content, providing key information on vegetation health.

  Various towns or settlements are represented in greys throughout the image.

  This false-colour image – also featured on the Earth from Space video programme – was captured by Sentinel-2A on 22 February 2016. The satellite is the first in the two-satellite Sentinel-2 mission for Europe’s Copernicus programme, carrying a wide-swath high-resolution instrument with 13 spectral bands, for a new perspective on our land and vegetation.

7th Meeting on Contemporary Mathematics

7th Meeting on Contemporary Mathematics

Geometric Flows and Applications

Gang Tian

Princeton University, USA and Peking University, China

	Gang Tian (Princeton University and Peking University)
	Geometric flows and applications
	Lecture Hall 1, IPM Niavaran Building Niavaran Square, Tehran
	The attendance is free, but requires registration Please fill out the registration form and  send it to  [e-mail]  with the subject "MCM

Nature Biomedical Engineering is now open for submissions

Nature Biomedical Engineering now accepting submissions Straddling the life sciences, the physical sciences and engineering, Nature Biomedical Engineering will publish — weekly and online-only — biological, medical and engineering advances that can directly inspire or lead to improvements in human health or healthcare. The journal is accepting original research submissions of the most important advances from the broad discipline of biomedical engineering, including materials, therapies, devices and methods that facilitate the understanding of human disease, or its prevention, diagnosis or treatment.

The first black hole candidate ultra-compact X-ray binary

The first black hole candidate ultra-compact X-ray binary in a globular cluster and its twisted accretion

Abstract

47 Tuc X9 is a low mass X-ray binary in the globular cluster 47 Tucanae, and was previously thought to be a cataclysmic variable (a white dwarf accreting from a main sequence star). Recently, we measured strong radio emission from this object, suggesting that the accretor is a black hole. I present result of our deep simultaneous study of this source in X-rays (with Chandra and NuSTAR) and in Radio (ATCA). We find a clear 28.18 minute periodic modulation in the Chandra data, which we identify as the orbital period, confirming this system as an ultracompact X-ray binary (orbital period < 80 mins) indicating the donor is a white dwarf. Additionally, we show evidence for clear signs of photo-ionized emission from oxygen VII and VIII in the system, providing additional evidence that the system is an ultra-compact X-ray binary and showing the donor is a Carbon/Oxygen white dwarf. Finally we detect a 6.8 day periodic modulation in the X-ray light curve, which indicates the presence of a warped accretion disk.

By: Arash Bahramian University of Albetra, Canada

Time:  Monday,  8 August / 18 Mordad, 11 AM

 Place: Particles and Astronomy seminar room, Larak building

Horizon Fluffs: A proposal for black hole quantum microstates

Speaker

Prof. M. M. Sheikh-Jabbari

Affliation

physics school,IPM

Title of talk

  Horizon Fluffs: A proposal for black hole quantum microstates

عنوان: "کُرک‌های افق": پسشنهادی برای ریز حالات کوانتمی سیاه‌چاله‌ها 

Date and time

Wednesday, 20th of Mordad (10th of August), 4:30 pm

Place

Farmanieh building, Amphitheater

Abstract

It is now an established fact that black holes behave as thermodynamical systems with a blackbody radiation, the Hawking radiation. Appearance of gravitational arrow of time (from gravitational collapse and formation of black hole to its evaporation due to Hawking radiation) and restoration of unitarity of black hole dynamics, as in any thermodynamical system, may be attributed to presence of an underlying microscopic statistical mechanical system. These microscopic degrees of freedom are usually called black hole microstates. Identifying the black hole microstates and counting them to get the black hole entropy, despite the progress in some very special cases, has remained a big challenge in theoretical high energy physics. 

In this talk I present the proposal we recently made for identification of certain three dimensional black hole microstates, the horizon fluffs proposal, and discuss how it may be extended to more realistic rotating Kerr black holes.

Index 2016 Nature

Talent scouts are trained to spot rising stars, the people and organizations that are not yet top of their field, but have the potential to shine more brightly than others Nature Index 2016 Rising Stars identifies the ascendant performers in the world of science, using the power of the Nature Index, which tracks the high-quality research of more than 8,000 global institutions In this supplement we profile the universities, research institutions and countries that have significantly improved their output, often without the longevity and resources which benefit many of the more established institutions that dominate academic rankings The Nature Index is a powerful tool to probe and compare research performance and collaboration within countries, and among them. Explore the data available on our websiteand discover your institution’s research strengths and partnerships Nicky Phillips Editor, Nature Index

A mathematician's approach to general relativistic quantum mechanics

A mathematician's approach to general relativistic quantum mechanics

---

---

Speaker

Prof. S. Tahvildar-Zadeh

Affiliation

Rutgers, the state university of New Jersey

Title of talk

A mathematician's approach to general relativistic quantum mechanics

«رهیافت یک ریاضی دان به مکانیک کوانتمی  سازگار با نسبیت عام» 

Abstract

I will describe a mathematical approach to the problem of 

incorporating relativistic gravity into quantum mechanics.  In this 

approach, particles are identified with certain joint singularities of 

the space-time and the electromagnetic field, whose motion --which cannot 

be dictated by the field equations themselves--  is instead  guided by a 

quantum mechanical wave function defined on the particle configuration 

space.  I will illustrate this point of view by re-examining the 

one-body Dirac equation for the electron in a Hydrogen atom (in 

Born-Oppenheimer approximation) and look at a few different ways of 

overcoming the main difficulty (already present at the classical level) 

in incorporating gravity into the picture, namely the problem of the 

infinite self-energy of point charges in Maxwell-Lorentz 

electrodynamics.  I will conclude by briefly remarking on a 

corresponding  many-body theory of electromagnetically interacting 

particles 

This is a joint project with Michael Kiessling