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Andrés García Saravia Ortíz de Montellano
Works at Cinvestav Mérida
Lives in Mérida, Yucatán
657 followers|18,248 views


I can do magic too!
Reverse Arrow Optical Illusion

Look Mah; I can do magic! This is a nice experiment to do with the kids. 

This is simply a demo of refraction: bending of light. #scienceeveryday  

A whimsical example:

Gif extracted from:
Physics Central info on Refraction:
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The BIG DEAL Explained (new comic!)

Full comic here:
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Really nice blog post!
"In fact, if we graphed how abundant all the different elements are in our Solar System, you’d find what appears to be a nice pattern, with some ups-and-downs, but a general curve where the lightest elements are the most abundant, and the abundance of the heavier ones gradually decreases as we move farther and farther down the periodic table.

Or rather that general pattern seems to hold, if you forget about elements three, four and five in the periodic table: lithium, beryllium and boron! These three elements are virtually non-existent in the Sun (or any star), and look awfully peculiar when compared to all the elements around them."

Where do lithium, beryllium and boron come from? Neither the Big Bang nor stars!
Every element found on Earth was made in either the Big Bang or the cores of stars… except these three.
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My PhD advisor is summarizing our latest efforst. Take a look at our open project here :)
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Which Tolkien quote is this?
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In his circles
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The Status of Data in Academic Research.

"There are very few, if any, discoveries each year in academia that come about without building on concepts and ideas that have been previously published in academic journals. This is the natural progression of research. However, this is often limited to building on top of conclusions or ideas, as opposed to the actual research itself. Current dissemination of research is largely based on making available pdf-based summaries of key findings, as opposed to the actual research outputs and raw data behind the graphs. In order to track a diverse array of academic outputs, they must persist on the Internet. One way to do this is via the minting of Digital Object Identifiers (DOIs) by trusted repositories. These managed links overcome the problem of ‘link rot’, which has been shown to occur at c. 10%/year for non-traditional outputs. This article addresses the current problems created by a lack of data sharing in academia. We also look at the incentives structure and potential solutions for improving the quality of academic outputs across all fields of research."

#openresearch   #opendata   #openscience  
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The German university of Konstanz cancels all Elsevier subscriptions, see
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¡También en español!
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Read Spanish?

La Inflación Cósmica Explicada: lea la comica aqui
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This week I was on a radio program to talk about the new results from BICEP2, which found the first evidence of cosmic inflation.  One of the questions I was asked was about the practical applications of this research.  I gave some mealy-mouthed answer about how cutting-edge research  can lead to new technologies we can’t even imagine, and gave an example of pure research leading to practical applications.  But afterwards, the more I thought about it, the more it became clear that it was the wrong answer.

The question about the practical applications of pure scientific research is a common one.  After all, if society is going to spend money on this kind of work, it has a right to demand some bang for its buck.  Right?

There is some truth to that.  There are times when particular areas of research are funded with a certain goal, such as targeted cancer research, or the development of higher density batteries.  But some research don’t have a goal other than the discovery of new things, and they are a success even if they don’t discover what we expect.  In the case of BICEP2, the project discovered real evidence of inflation.  Even if the project produces no “practical” applications it has been a success, because we now know (assuming the results hold up) that inflation occurred in the early universe.  Not just suspect because it would answer many questions about the big bang, but truly know.  We have more knowledge about the universe than we had before, and that matters.

When someone asks about the practical implications, they take a small view of science.  It ignores the fact that scientific knowledge is itself valuable. Science arises from the innate curiosity that is part of what makes us human.  To do science well requires some of the best aspects of humanity: thoughtfulness, honesty, skepticism, creativity and equality.  It requires us to work together, and it drives us to communicate ideas clearly.  It is a human endeavor that inspires us to do better, and to be better.

It also requires us to look to the future, not just the past.  We invest in scientific research now so that we can make scientific discoveries in the future. The knowledge we gain is not just valuable for us, but for future generations.  By investing in science we are able to bequeath to our children a greater understanding of the universe than we were given. It’s true that pure scientific research will inevitably lead to new practical applications.  It will give rise to new industries we can’t currently imagine. But that shouldn’t be the reason why we invest in science.

Science is a profound act of hope.  It is what a hopeful and forward looking society does. And that’s why we should do it.

Image: NRAO/AUI (
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Very interesting summary about  a recent  article in Nature dealing  with black holes
Turn, Turn, Turn

While they were once a mystery, we now know quasars are driven by black holes in the center of galaxies, and are part of a larger class of objects known as active galactic nuclei, or AGNs.  What makes quasars distinctive is that they are very bright, and their light is highly redshifted.  This latter property means that they are also very far away.  Because of their great distance, the light from quasars began their journey billions of years ago.  This means the study of quasars allow us to understand the earliest examples of active black holes.  The great distance of quasars also poses a challenge, because it is difficult to measure the properties of an object billions of light years away.  But sometimes a bit of luck will allow astronomers to make some good observations.  Such is the case of a recent paper in Nature which measures the rotation of a quasar’s black hole.

The particular quasar in question has a redshift of z = 0.658, which means its light left the quasar about six billion years ago.  It also happens to be behind a much closer galaxy from our viewpoint.  You might think that might make observing the quasar worse, but in away it is actually a good thing. The mass of the close galaxy acts as a gravitational lens, bending the light of the quasar a bit, and focusing it in our direction.  This means we actually see more light from the quasar than we would if the closer galaxy wasn’t there.  Of course the galaxy also distorts the light coming from the quasars, so the team had to reconstruct the image of the quasar using the gravitationally lensed light.

Doing that, they then had a strong enough x-ray source from the quasar to analyze its rotation.  This is done by looking at light reflected off its accretion disk.  The region around the supermassive black hole of the quasar generates intense x-rays, and some of it reflects off material in the accretion disk.  The motion of the accretion disk around the black hole means that some of the reflected light is redshifted more than the average for the quasar, and some less.  By measuring this difference it is possible to measure the rotation of the accretion disk, which in turn allows us to determine the rotation of the black hole.

The rotation of a black hole is often given as a parameter known as “a”.  This parameter can have a value between 0 (no rotation) and 1 (maximum possible rotation).  Sometimes in the popular press it is stated that the maximum rotation rate is the speed of light, but that isn’t quite how things work.  So we’ll stick with “a” as a measure of its rotation.  What the authors found was that this particular quasar had a rotation of at least a = 0.66, and very possibly as high as a = 0.87.  This is a very high rotation rate, and it likely means this particular black hole formed as a merger between two smaller black holes.

What makes this interesting is that it hints at early supermassive black holes forming by mergers.  By the time the universe was 7 billion years old, two supermassive black holes had formed, then merged to produce this fast-rotating supermassive black hole.  Of course this is only one example, so we don’t know if such fast-rotating quasars are common or exceptional.

What we do know is that even early black holes can rotate very fast indeed.

Image: NASA/CXC/Univ of Michigan/R.C.Reis et al

Paper:  R. C. Reis, M. T. Reynolds, J. M. Miller & D. J. Walton. Reflection from the strong gravity regime in a lensed quasar at redshift z = 0.658. Nature. doi:10.1038/nature13031 (2014)
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In his circles
106 people
Have him in circles
657 people
Alfonso Palma's profile photo
Diego Fernando Mulato Gómez's profile photo
Ezequiel Arceo May's profile photo
Estudiante de Doctorado en Ciencias con especialidad en Física Aplicada
Habilidades analíticas en Física y Matemáticas. Programación en Lisp, Python, R, Octave y otros.
  • Cinvestav Mérida
    Estudiante, 2008 - present
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Mérida, Yucatán
Físico por profesión y vocación.
    Doctorado en Ciencias con Especialidad en Física Aplicada, 2010 - present
    Doctorado en Ciencias por parte del Departamento de Física Aplicada del Cinvestav Unidad Mérida. Mi trabajo actual es sobre modelos polarónicos en superconductores de alta temperatura basados en Cobre.
  • Benemérita Universidad Autónoma de Puebla
    Licenciatura en Física, 2003 - 2007
    Licenciatura en Física por parte de la Facultad de Ciencias Físico-Matemáticas
    Maestría en Ciencias con Especialidad en Física Aplicada, 2008 - 2010
    Maestría en Ciecnias por parte del Departamento de Física del Cinvestav Unidad Mérida. Mi tesis fue en el tema de Superconductores de Alta temperatura basados en Hierro. El título fue "Cálculos de Absorción de Rayos X en ReOFeAs (con Re una tierra rara)"
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