Theories about the Origins of Space and Time. 1. Gravity as Thermodynamics Entropic gravity is a theory in modern physics that describes gravity as an entropic force - not a fundamental interaction mediated by a quantum field theory and a gauge particle, but a consequence of physical systems’ tendency to increase their entropy. 2. Loop Quantum Gravity According to Einstein, gravity is not a force – it is a property of space-time itself. Loop quantum gravity is an attempt to develop a quantum theory of gravity based directly on Einstein’s geometrical formulation. The main output of the theory is a physical picture of space where space is granular. More precisely, space can be viewed as an extremely fine fabric or network “woven” of finite loops. These networks of loops are called spin networks. The evolution of a spin network over time is called a spin foam. The predicted size of this structure is the Planck length, which is approximately 10−35 meters. According to the theory, there is no meaning to distance at scales smaller than the Planck scale. Therefore, LQG predicts that not just matter, but space itself, has an atomic structure. 3. Causal Sets Its founding principles are that spacetime is fundamentally discrete and that spacetime events are related by a partial order. The theory postulates that the building blocks of space-time are simple mathematical points that are connected by links, with each link pointing from past to future. Such a link is a bare-bones representation of causality, meaning that an earlier point can affect a later one, but not vice versa. The resulting network is like a growing tree that gradually builds up into space-time. 4. Causal Dynamical Triangulations The idea is to approximate the unknown fundamental constituents with tiny chunks of ordinary space-time caught up in a roiling sea of quantum fluctuations, and to follow how these chunks spontaneously glue themselves together into larger structures. The space-time building blocks were simple hyper-pyramids (four-dimensional counterparts to three-dimensional tetrahedrons) and the simulation’s gluing rules allowed them to combine freely. The result was a series of bizarre ‘universes’ that had far too many dimensions (or too few), and that folded back on themselves or broke into pieces. 5. Holography In this model, the three-dimensional interior of the universe contains strings and black holes governed only by gravity, whereas its two-dimensional boundary contains elementary particles and fields that obey ordinary quantum laws without gravity. Hypothetical residents of the three-dimensional space would never see this boundary, because it would be infinitely far away. But that does not affect the mathematics: anything happening in the three-dimensional universe can be described equally well by equations in the two-dimensional boundary, and vice versa.
Our OSIRIS-REx spacecraft will travel to a near-Earth asteroid, called Bennu, where it will collect a sample to bring back to Earth for study.
But why was Bennu chosen as the target destination asteroid for OSIRIS-REx? The science team took into account three criteria: accessibility, size and composition.
Accessibility: We need an asteroid that we can easily travel to, retrieve a sample from and return to Earth, all within a few years time. The closest asteroids are called near-Earth objects and they travel within 1.3 Astronomical Units (AU) of the sun. For those of you who don’t think in astronomical units…one Astronomical Unit is approximately equal to the distance between the sun and the Earth: ~93 million miles.
For a mission like OSIRIS-REx, the most accessible asteroids are somewhere between 0.08 – 1.6 AU. But we also needed to make sure that those asteroids have a similar orbit to Earth. Bennu fit this criteria! Check!
Size: We need an asteroid the right size to perform two critical portions of the mission: operations close to the asteroid and the actual sample collection from the surface of the asteroid. Bennu is roughly spherical and has a rotation period of 4.3 hours, which is in our size criteria. Check!
Composition: Asteroids are categorized by their spectral properties. In the visible and infrared light minerals have unique signatures or colors, much like fingerprints. Scientists use these fingerprints to identify molecules, like organics. For primitive, carbon-rich asteroids like Bennu, materials are preserved from over 4.5 billion years ago! We’re talking about the start of the formation of our solar system here! These primitive materials could contain organic molecules that may be the precursors to life here on Earth, or elsewhere in our solar system.
Thanks to telescopic observations in the visible and the infrared, as well as in radar, Bennu is currently the best understood asteroid not yet visited by a spacecraft.
All of these things make Bennu a fascinating and accessible asteroid for the OSIRIS-REx mission.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
These two spacecraft are called STEREO, short for Solar and Terrestrial Relations Observatory. Launched on Oct. 25, 2006, and originally slated for a two-year mission, both spacecraft sent back data for nearly eight years, and STEREO-A still sends information and images from its point of view on the far side of the sun.
STEREO watches the sun from two completely new perspectives. It also provides information invaluable for understanding the sun and its impact on Earth, other worlds, and space itself – collectively known as space weather. On Earth, space weather can trigger things like the aurora and, in extreme cases, put a strain on power systems or damage high-flying satellites.
Because the rest of our sun-watching satellites orbit near our home planet, STEREO’s twin perspectives far from Earth give us a unique opportunity to look at solar events from all sides and understand them in three dimensions.
We use data from STEREO and other missions to understand the space environment throughout the solar system. This helps operators for missions in deep space prepare for the sudden bursts of particles and magnetic field that could pose a danger to their spacecraft.
STEREO has also helped us understand other objects in our solar system – like comets. Watching how a comet’s tail moves gives us clues about the constant stream of particles that flows out from the sun, called the solar wind.
STEREO is an essential piece of our heliophysics fleet, which includes 17 other missions. Together, these spacecraft shed new light on the sun and its interaction with space, Earth, and other worlds throughout the solar system.
To celebrate, we’re hosting a Facebook Live event on Wednesday, Oct. 26. Join us at noon ET on the NASA Sun Science Facebook page to learn more about STEREO and ask questions.
Learn more about how NASA studies the sun at: www.nasa.gov/stereo
Follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
The satellite was little— the size of a small refrigerator; it was only supposed to last one year and constructed and operated on a shoestring budget — yet it persisted.
After 17 years of operation, more than 1,500 research papers generated and 180,000 images captured, one of NASA’s pathfinder Earth satellites for testing new satellite technologies and concepts comes to an end on March 30, 2017. The Earth Observing-1 (EO-1) satellite will be powered off on that date but will not enter Earth’s atmosphere until 2056.
“The Earth Observing-1 satellite is like The Little Engine That Could,” said Betsy Middleton, project scientist for the satellite at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
To celebrate the mission, we’re highlighting some of EO-1’s notable contributions to scientific research, spaceflight advancements and society.
This animation shifts between an image showing flooding that occurred at the Arkansas and Mississippi rivers on January 12, 2016, captured by ALI and the rivers at normal levels on February 14, 2015 taken by the Operational Land Imager on Landsat 8. Credit: NASA’s Earth Observatory
EO-1 carried the Advanced Land Imager that improved observations of forest cover, crops, coastal waters and small particles in the air known as aerosols. These improvements allowed researchers to identify smaller features on a local scale such as floods and landslides, which were especially useful for disaster support.
On the night of Sept. 6, 2014, EO-1’s Hyperion observed the ongoing eruption at Holuhraun, Iceland as shown in the above image. Partially covered by clouds, this scene shows the extent of the lava flows that had been erupting.
EO-1’s other key instrument Hyperion provided an even greater level of detail in measuring the chemical constituents of Earth’s surface— akin to going from a black and white television of the 1940s to the high-definition color televisions of today. Hyperion’s level of sophistication doesn’t just show that plants are present, but can actually differentiate between corn, sorghum and many other species and ecosystems. Scientists and forest managers used these data, for instance, to explore remote terrain or to take stock of smoke and other chemical constituents during volcanic eruptions, and how they change through time.
EO-1 was one of the first satellites to capture the scene after the World Trade Center attacks (pictured above) and the flooding in New Orleans after Hurricane Katrina. EO-1 also observed the toxic sludge in western Hungary in October 2010 and a large methane leak in southern California in October 2015. All of these scenes, which EO-1 provided quick, high-quality satellite imagery of the event, were covered in major news outlets. All of these scenes were also captured because of user requests. EO-1 had the capability of being user-driven, meaning the public could submit a request to the team for where they wanted the satellite to gather data along its fixed orbits.
This image shows toxic sludge (red-orange streak) running west from an aluminum oxide plant in western Hungary after a wall broke allowing the sludge to spill from the factory on October 4, 2010. This image was taken by EO-1’s Advanced Land Imager on October 9, 2010. Credit: NASA’s Earth Observatory
This image of volcanic activity on Antarctica’s Mount Erebus on May 7, 2004 was taken by EO-1’s Advanced Land Imager after sensing thermal emissions from the volcano. The satellite gave itself new orders to take another image several hours later. Credit: Earth Observatory
EO-1 was among the first satellites to be programmed with a form of artificial intelligence software, allowing the satellite to make decisions based on the data it collects. For instance, if a scientist commanded EO-1 to take a picture of an erupting volcano, the software could decide to automatically take a follow-up image the next time it passed overhead. The Autonomous Sciencecraft Experiment software was developed by NASA’s Jet Propulsion Laboratory in Pasadena, California, and was uploaded to EO-1 three years after it launched.
This image of Nassau Bahamas was taken by EO-1’s Advanced Land Imager on Oct 8, 2016, shortly after Hurricane Matthew hit. European, Japanese, Canadian, and Italian Space Agency members of the international coalition Committee on Earth Observation Satellites used their respective satellites to take images over the Caribbean islands and the U.S. Southeast coastline during Hurricane Matthew. Images were used to make flood maps in response to requests from disaster management agencies in Haiti, Dominican Republic, St. Martin, Bahamas, and the U.S. Federal Emergency Management Agency.
The artificial intelligence software also allows a group of satellites and ground sensors to communicate and coordinate with one another with no manual prompting. Called a “sensor web”, if a satellite viewed an interesting scene, it could alert other satellites on the network to collect data during their passes over the same area. Together, they more quickly observe and downlink data from the scene than waiting for human orders. NASA’s SensorWeb software reduces the wait time for data from weeks to days or hours, which is especially helpful for emergency responders.
This animation shows the Rodeo-Chediski fire on July 7, 2002, that were taken one minute apart by Landsat 7 (burned areas in red) and EO-1 (burned areas in purple). This precision formation flying allowed EO-1 to directly compare the data and performance from its land imager and the Landsat 7 ETM+. EO-1’s most important technology goal was to test ALI for future Landsat satellites, which was accomplished on Landsat 8. Credit: NASA’s Goddard Space Flight Center
EO-1 was a pioneer in precision “formation flying” that kept it orbiting Earth exactly one minute behind the Landsat 7 satellite, already in orbit. Before EO-1, no satellite had flown that close to another satellite in the same orbit. EO-1 used formation flying to do a side-by-side comparison of its onboard ALI with Landsat 7’s operational imager to compare the products from the two imagers. Today, many satellites that measure different characteristics of Earth, including the five satellites in NASA’s A Train, are positioned within seconds to minutes of one another to make observations on the surface near-simultaneously.
For more information on EO-1’s major accomplishments, visit: https://www.nasa.gov/feature/goddard/2017/celebrating-17-years-of-nasa-s-little-earth-satellite-that-could
I believe in free education, one that’s available to everyone; no matter their race, gender, age, wealth, etc… This masterpost was created for every knowledge hungry individual out there. I hope it will serve you well. Enjoy!
FREE ONLINE COURSES (here are listed websites that provide huge variety of courses)
Alison
Coursera
FutureLearn
open2study
Khan Academy
edX
P2P U
Academic Earth
iversity
Stanford Online
MIT Open Courseware
Open Yale Courses
BBC Learning
OpenLearn
Carnegie Mellon University OLI
University of Reddit
Saylor
IDEAS, INSPIRATION & NEWS (websites which deliver educational content meant to entertain you and stimulate your brain)
TED
FORA
Big Think
99u
BBC Future
Seriously Amazing
How Stuff Works
Discovery News
National Geographic
Science News
Popular Science
IFLScience
YouTube Edu
NewScientist
DIY & HOW-TO’S (Don’t know how to do that? Want to learn how to do it yourself? Here are some great websites.)
wikiHow
Wonder How To
instructables
eHow
Howcast
MAKE
Do it yourself
FREE TEXTBOOKS & E-BOOKS
OpenStax CNX
Open Textbooks
Bookboon
Textbook Revolution
E-books Directory
FullBooks
Books Should Be Free
Classic Reader
Read Print
Project Gutenberg
AudioBooks For Free
LibriVox
Poem Hunter
Bartleby
MIT Classics
Many Books
Open Textbooks BCcampus
Open Textbook Library
WikiBooks
SCIENTIFIC ARTICLES & JOURNALS
Directory of Open Access Journals
Scitable
PLOS
Wiley Open Access
Springer Open
Oxford Open
Elsevier Open Access
ArXiv
Open Access Library
LEARN:
1. LANGUAGES
Duolingo
BBC Languages
Learn A Language
101languages
Memrise
Livemocha
Foreign Services Institute
My Languages
Surface Languages
Lingualia
OmniGlot
OpenCulture’s Language links
2. COMPUTER SCIENCE & PROGRAMMING
Codecademy
Programmr
GA Dash
CodeHS
w3schools
Code Avengers
Codelearn
The Code Player
Code School
Code.org
Programming Motherf*?$%#
Bento
Bucky’s room
WiBit
Learn Code the Hard Way
Mozilla Developer Network
Microsoft Virtual Academy
3. YOGA & MEDITATION
Learning Yoga
Learn Meditation
Yome
Free Meditation
Online Meditation
Do Yoga With Me
Yoga Learning Center
4. PHOTOGRAPHY & FILMMAKING
Exposure Guide
The Bastards Book of Photography
Cambridge in Color
Best Photo Lessons
Photography Course
Production Now
nyvs
Learn About Film
Film School Online
5. DRAWING & PAINTING
Enliighten
Ctrl+Paint
ArtGraphica
Google Cultural Institute
Drawspace
DragoArt
WetCanvas
6. INSTRUMENTS & MUSIC THEORY
Music Theory
Teoria
Music Theory Videos
Furmanczyk Academy of Music
Dave Conservatoire
Petrucci Music Library
Justin Guitar
Guitar Lessons
Piano Lessons
Zebra Keys
Play Bass Now
7. OTHER UNCATEGORIZED SKILLS
Investopedia
The Chess Website
Chesscademy
Chess.com
Spreeder
ReadSpeeder
First Aid for Free
First Aid Web
NHS Choices
Wolfram Demonstrations Project
Please feel free to add more learning focused websites.
*There are a lot more learning websites out there, but I picked the ones that are, as far as I’m aware, completely free and in my opinion the best/ most useful.
The eye is a basically a dipole ( a separation of electric charges )
It was observed by Reymond in 1848 that the cornea of the eye is electrically positive relative to the back of the eye.This potential was surprisingly not dependent on the amount of light falling on the eye.
The cornea is the transparent front part of the eye
This means that as the eye moves from side to side, the dipole moves as well. To capture the movement of the dipole, one places two electrodes on both sides of the eye. ( like the one placed on this guy )
If the eye moves from the center position to the right, one of the electrodes becomes slightly positive and the other negative. This leads to a spike in the positive direction.
Source
And if the eye moves from the center position to the left, the polarity of the electrodes reverses. This leads to a spike in the negative direction.
That’s about it. That’s EOG for you all. I hope you guys enjoyed this post.
Have a great day!
Sources and Extras:
More about EOG
Gif source : The backyard brains
Window phone concept
Is it a window, is it a phone? No. Actually, it’s Window phone and this is the part where you are saying “Whaaat? What are you talking about?”. The phone is actually a concept with extraordinary features. Surely if this could be actually put into production, it would set a new standard for the term “cool”.
Comments of the Week #92: from the Universe’s birth to ten decades of science
“[I]f there were antimatter galaxies out there, then there should be some interface between the matter and antimatter ones. Either there would be a discontinuity (like a domain wall) separating the two regions, there would be an interface where gamma rays of a specific frequency originated, or there would be a great 2D void where it’s all already annihilated away.
And our Universe contains none of these things. The absence of them in all directions and in all locations tells us that if there are antimatter galaxies out there, they’re far beyond the observable part of our Universe. Instead, every interacting pair we see shows evidence that they’re all made of matter. Beautiful, beautiful matter.”
There’s no better way to start 2016 than… with a bang! Come check out our first comments of the week of the new year.
Willst du immer weiter schweifen? Sieh, das Gute liegt so nah!
Do you want to roam further and further? Look, the good things are so close!
Johann Wolfgang von Goethe (1749 – 1832), German poet, dramatist, natural scientist, and statesman
(via thatswhywelovegermany)
Star Clouds Toward the Southern Crown
The Great Nebula in Carina : In one of the brightest parts of Milky Way lies a nebula where some of the oddest things occur. NGC 3372, known as the Great Nebula in Carina, is home to massive stars and changing nebulas. The Keyhole Nebula , the bright structure just above the image center, houses several of these massive stars and has itself changed its appearance. The entire Carina Nebula spans over 300 light years and lies about 7,500 light-years away in the constellation of Carina. Eta Carinae, the most energetic star in the nebula, was one of the brightest stars in the sky in the 1830s, but then faded dramatically. Eta Carinae is the brightest star near the image center, just left of the Keyhole Nebula. While Eta Carinae itself maybe on the verge of a supernova explosion, X-ray images indicate that much of the Great Carina Nebula has been a veritable supernova factory. via NASA
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