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Andrew Planet
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At the beginning of the 20th century, we were just beginning to map out our galaxy. By its end we had discovered a universe billions of light years across.
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Andrew Planet

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Have you ever wondered how astronomers simulate the large-scale structure of the universe?  How do they answer questions like, 'What will #JWST show us?' or 'What can we expect to learn from #WFIRST ?'

The Space Telescope Science Institute is hosting a mini-workshop this week featuring techniques for simulating the universe where they delve into these questions and many more.

This workshop will focus on the interface of models and survey design: how can we best inject and extract astrophysical insight into and from data simulations?

One of the main aims is to identify common ground between various ongoing data simulation efforts associated with diverse facilities on the ground and in space (e.g., ELTs, JWST, LSST, PanSTARRS, WFIRST, ALMA, Euclid etc.).

Please join +Tony Darnell Dr +Carol Christian and +Scott Lewis as they discuss simulating the universe with astronomers +Molly Peeples and Joshua Peek.  We look forward to hearing your comments and questions as well!

#Space   #astronomy #Hubble25   #cosmology
This Hangout On Air is hosted by Hubble Space Telescope. The live video broadcast will begin soon.
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Mocking The Universe: Better Science Through Data Simulation
Thu, July 30, 3:00 PM
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Andrew Planet
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In physics events are often time symmetric, so why is it that time so clearly seems to have a specific direction?
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Andrew Planet
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The Peacock Problem

‘The sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick!’ So wrote Charles Darwin in a letter to his friend, expressing his frustration at not being able to explain how natural selection could drive the evolution of this extravagantly ornamental display. Not only was there an obvious lack of survival advantage to an awkwardly heavy appendage, it came with an energy cost and added vulnerability to predators. How then, did the peacock's tail evolve?

Once again, it was Darwin who came up with the idea of sexual selection, that depends, "not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring"
  
By flaunting his "handicap", the peacock signals to his potential mate that he has survived despite the negative consequences! The good gene hypothesis suggests that the ornament is a proxy for a healthy immune system and metabolic fitness. The peahen's preference for gaudy displays drives the evolution of the tail by positive feedback: when she mates with the most fashionable male, she passes his traits on to her sons who in turn, are assured of reproductive success! Choosy mothers produce sexy sons and over many generations, runaway evolution results in strange and beautiful ornamentations like the lion's mane, the antlers of a stag and the blue-footed booby. In the 20th century, Ronald Fisher, who is considered the greatest evolutionary biologist after Darwin, argued that the female's preference and the male's development of the ornament must advance together until practical or physical limits halt any further exaggeration (http://en.wikipedia.org/wiki/Fisherian_runaway). 

We've seen how sexual selection gives rise to the difference in appearance between male and female (sexual dimorphism). Animals that are monogamous show less sexual dimorphism. Interestingly, our pre-Homo ancestors may have been more dimorphic compared to modern humans suggesting that we have become more monogamous over time! 

REF:The sight of the peacock's tail makes me sick: the early arguments on sexual selection. (2000) Hiraiwa-Hasegawa M. http://www.ncbi.nlm.nih.gov/pubmed/10824193

#ScienceSunday  
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Andrew Planet
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Its amazing how Google can give credit to the coining of a new term with just the mere usage of 2 words. Sumptuary sublimation

I've got an ever increasing list of such terms which I invent to memorize concepts

With Google being already so advanced and, measuring modernity, "today is someone else's stone age"  what will the future bring I wonder

http://dictionary.reference.com/browse/sumptuary?s=t

http://dictionary.reference.com/browse/sublimation?s=t

Google Search  "today is someone else's stone age"  https://www.google.com/search?q=today+is+someone+else%27s+stone+age&ie=utf-8&oe=utf-8
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Andrew Planet
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Stephen Pinker: Violence has fallen

The psychologist says statistics show less violence around the world today than previous decades.

#Steven Pinker #War #Conflict #Violence
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Andrew Planet
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Wilczek forecasts that large-scale quantum computers will be realized, in turn leading to “quantum artificial intelligence.”

“A quantum mind could experience a superposition of ‘mutually contradictory’ states, or allow different parts of its wave function to explore vastly different scenarios in parallel,” Wilczek points out. “Being based on reversible computation, such a mind could revisit the past at will, and could be equipped to superpose past and present.”

And with quantum artificial intelligence at its disposal, the human mind’s sensory tentacles will not merely be enhanced but also dispersed. With quantum communication, humans can be linked by quantum messaging to sensory devices at vast distances from their bodies. “An immersive experience of ‘being there’ will not necessarily involve being there, physically,” Wilczek writes. “This will be an important element of the expansion of human culture beyond Earth.”

http://bit.ly/1c2kPoA
A Nobel laureate forecasts deeper understanding of physics and new powers for the human mind in the century to come.
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Andrew Planet
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The Types of Intelligence

In 1983 Howard Gardener described 9 types of intelligence:

1: Logical-mathematical
2: Linguistic
3: Bodily kinesthetic
4: Musical
5: Naturalist
6: Interpersonal
7: Intra-personal
8: Spacial
9: Existential

What other scientists thought were just soft-skills, such as interpersonal skills, Gardener realized were types of intelligence. It makes sense. Just as being a math whiz gives you the ability to understand the world, so does being “people smart” give you the same ability, just from a different perspective. Not knowing math you may not calculate the rate at which the universe is expanding, but you are likely to have the skills to find the right person who will.

Even 20 years after Gardener’s book came out, there is still a debate whether talents other than math and language are indeed types of intelligence or just skills. What do you think?

#psychology #productivity #infographic #intelligence #talent #mind

Via: http://fundersandfounders.com
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Andrew Planet
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This Women’s History Month, Science Friday celebrates some of the unsung heroines of science.
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About this community

There exists a wide variety of people whose personal belief system is based purely on experimentally verifiable facts. These may be atheists or people who believe in a God so I wish to find a common ground for all of them in this community. This is work in progress

Andrew Planet
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Why do young stars contain so much lithium? That might seem an odd question, but it's a question that has nagged astronomers for quite some time.
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Andrew Planet
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One way that stars are categorized is by temperature. Since the temperature of a star can determine its visual color, this category scheme is known as spectral type. The main categories of spectral type are M, K, G, F, A, B, and O. The coolest stars (red dwarfs) being M, and the hottest stars being O. Our own Sun is a G star.
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Andrew Planet
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What If Light Had No Speed Limit?

What would the universe be like if the speed of light were infinite? It might seem like a silly question, since the speed of light clearly isn’t infinite, but questions like these are a good way to explore how different aspects of a physical model are interrelated.

For example, in our universe light is an electromagnetic wave. It not only has a speed, but a wavelength. If you think of a wave as an oscillation, then at infinite speed light would have no time to oscillate. So infinite light can’t be a wave. Since the wavelength of light determines its color, that would also mean it has no color. But it gets worse because in classical physics light is produced when electromagnetic waves cause the charges in atoms and molecules to oscillate. Without waves, atoms can’t be induced to emit light, the universe would be a sea of darkness.

But real light actually has both wave and particle aspects, so let’s suppose that for infinite light it’s just some kind of particle so we can still have light and color without all that meddling wave business. What else would change?

Relativity is an obvious choice. Einstein’s theory of relativity depends upon a finite speed of light. With an infinite light speed, all those fun things like time dilation are thrown out the window. So is Einstein’s most famous equation, E = mc2. The main consequence of this equation is that matter can be transformed into energy and vice versa. It’s central to things like nuclear fusion, which powers the stars and creates the heavy elements. Stars could still be powered by gravitational contraction, but they would only last for a million years rather than billions of years. They also wouldn’t have any mechanism to explode as supernovae, so there would be no way to make new stars from old ones.

Since Einstein’s theory of gravity is a generalization of special relativity, it goes away too. Our model of the universe, beginning with a big bang and expanding through dark energy, depends upon Einstein’s theory. Without it the universe look very different. No dark energy, possibly no big bang.

Of course this is all just a game of pretend. If you made different assumptions about physical phenomena you would derive different effects. We have no way of knowing what an infinite light speed universe would really be like. But what this shows is just how interconnected different aspects of a physical model actually are. Any tweak to the model has consequences that can ripple into widely different areas, or even cause an entire model to collapse.
What would the universe be like if the speed of light were infinite?
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Andrew Planet
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Sizing Things Up

Quasars are very bright objects that are generally billions of light years away. We now know that they are a kind of active galactic nuclei (AGN) and are powered by supermassive black holes in the centers of galaxies. We know this in part because they emanate from within galaxies, and their energy comes from a region only a few light years across. But how do we know the size of something from billions of light years away?

At that distance, a quasar is too small for us to measure its size directly, but we can do it indirectly by measuring the variation in a quasar’s brightness. Take, for example, the brightest quasar in our sky (in the visible spectrum) known as 3C 273. It’s redshift puts it at about 2.5 billion light years away. Because of its brightness and relative closeness, it is one of the most studied quasars. So we actually have quite a bit of data on it. One of the things we’ve observed is that its brightness oscillates over time, getting slightly brighter and dimmer about 15 times a year. We see this variability in other quasars, but 3C 273 is the most accurately measured.

A varying brightness is interesting because it tells us something about the size of the source. Basically if an object is changing brightness, it can’t do that at a rate faster than the time it takes one side of the object to know what the other side is doing. That time is limited by the speed of light, so if you know the rate at which brightness varies, you know the maximum possible size of the object. Since these objects are also greatly redshifted we have to account for that as well (high redshift means time dilation), but that’s pretty easy to do. So we can take our quasar and AGN observations and calculate a maximum size for each one. Taking data for various quasars, I’ve plotted how many are at each particular size. While they vary in size, the most common size is most commonly around 5 on this graph, which equates to 100,000 AU, or about 1.5 light years across.

That might seem pretty big, but remember that these objects are brighter than our galaxy (consisting of 200 billion stars). On a galactic scale these objects are tiny. Given their large brightness and tiny size, we can say pretty confidently that they are powered by black holes. There’s other evidence to support this conclusion, but that’s a story for another time.
How do we determine the size of a quasar billions of light years away? We observe the rate at which they vary in brightness.
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Andrew Planet
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Real and Unreal

Quantum theory is strange, but very real. Through countless experiments we’ve found that quantum objects have both particle-like and wave-like properties. In some experiments the particle nature dominates, while in others the wave nature dominates. Some experiments can even show the effects of both properties. This duality between particles and waves in quantum theory is deeply counterintuitive, which means often the results of quantum experiments are interpreted incorrectly.

Take, for example, recent claims that reality doesn’t exist until we measure it. The claims arise from a recent experiment published in Nature that uses a single atom to perform what is known as the delayed-choice experiment. This experiment was first proposed as a thought experiment (gedanken experiment) by John Wheeler as a way of exploring the counterintuitive aspects of particle-wave duality.

Wheeler’s idea was to imagine a “cosmic interferometer.” Suppose light from a distant distant quasar were to be gravitationally lensed by closer galaxy. As a result, light from a single quasar would appear as coming from two slightly different locations. Wheeler then noted that this light could be observed in two different ways. The first would be to have a detector aimed at each lensed image, thus making a particle measurement. The second would be to combine light from these two images in an interferometer, thus making a wave measurement. According to quantum theory, the results of these two types of experiments (particle or wave) would be exactly as we’ve observed in their standard form. But the light began its journey billions of years ago, long before we decided on which experiment to perform. Through this “delayed choice” it would seem as if the quasar light “knew” whether it would be seen as a particle or wave billions of years before the experiment was devised.

Although the quasar experiment Wheeler proposed isn’t practical, modern experimental equipment allows us to perform a similar experiment in the lab, where the decision to measure a particle or wave is done at random after the quantum system is “committed.” For example, in 2007 a delayed-choice experiment was made using laser light to create a delayed-choice double slit experiment. In this new paper, the team used an ultracold helium atom to do a similar delayed-choice interference experiment. With both experiments the results were exactly as predicted by quantum theory. So both matter and light exhibit this strange quantum effect.

While this is great work, the result isn’t unexpected. Quantum theory made a very clear prediction about this kind of experiment, and its prediction has been confirmed. Where things get fuzzy is in the interpretation. One popular way to interpret quantum theory is to presume quanta have a potential wavefunction, which then collapses into a definite state when observed. In this view the act of measurement gives reality to the quantum. In the delayed-choice experiment that would mean the quantum doesn’t become “real” until you measure it, which could be billions of years after its origin in the case of quasar light. But this is an overly simplistic take on things. Quantum objects are real, but simply have indefinite properties. These properties are defined by the experiments we do. What the delayed choice experiments really show is that quanta don’t exist as particles or waves, but are truly unique objects which can exhibit particle and wave properties in certain experiments.

While that might seem strange, it isn’t magical or mystical. The Moon wouldn’t vanish from existence if everyone closed their eyes, and reality isn’t dependent upon us observing it.

Paper: A. G. Manning, et al. Wheeler’s delayed-choice gedanken experiment with a single atom. Nature Physics, DOI: 10.1038/nphys3343 (2015)

Paper: Jacques, V. et al. Experimental realization of Wheeler’s delayed-choice gedanken experiment. Science 315, 966–968 (2007).
The delayed choice experiment has been performed in the lab. What the results say about the nature of reality isn't quite what many claim.
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Andrew Planet
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Wilczek forecasts that large-scale quantum computers will be realized, in turn leading to “quantum artificial intelligence.”

“A quantum mind could experience a superposition of ‘mutually contradictory’ states, or allow different parts of its wave function to explore vastly different scenarios in parallel,” Wilczek points out. “Being based on reversible computation, such a mind could revisit the past at will, and could be equipped to superpose past and present.”

And with quantum artificial intelligence at its disposal, the human mind’s sensory tentacles will not merely be enhanced but also dispersed. With quantum communication, humans can be linked by quantum messaging to sensory devices at vast distances from their bodies. “An immersive experience of ‘being there’ will not necessarily involve being there, physically,” Wilczek writes. “This will be an important element of the expansion of human culture beyond Earth.”

http://bit.ly/1c2kPoA
A Nobel laureate forecasts deeper understanding of physics and new powers for the human mind in the century to come.
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Andrew Planet
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Costa Rica has achieved a clean energy milestone by using 100 per cent renewable energy for a record 75 days in a row.
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Andrew Planet
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Our species is still changing. What will become of it?
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