The Israel-Palestine conflict is one that has been fraught with violence and displacement, more so for the Palestinians. This is a complicated history of war and disagreement over the possible solutions. However in recent years, the actions of Israel’s right-wing coalition government under Prime Minister Benjamin Netanyahu are making the path to peace even more difficult.
Many artists, especially those of Palestinian origin, across the creative mediums, have turned to art as a medium of expression against the Israeli government’s repressive policies and to show the suffering of the Palestinian people.
Graffiti of Marouane Barghouti, imprisoned Palestinian activist | Source: thierry ehrmann via Flickr
The heroes of Palestinian resistance against the Israeli occupation are a popular subject of resistance art by Palestinian artists. It is mainly expressed in the form of murals, graffities, and posters.
Another important theme in Palestinian art surrounds the Nakba, which refers to the exodus of a large number of Palestinians after the formation of the state of Israel.
Palestinian refugees leaving the Galilee in October–November 1948 | Source: Fred Csasznik via Wikimedia
A popular street artist Banksy has left his unique mark in support of Palestinian resistance, and not just in the form of street art which lines the Israeli West Bank barrier and other areas of the West Bank.
Banksy also opened the Walled Off Hotel in 2014 where all the rooms overlook the barrier or apartheid wall, as it is known in Palestine, and each contains various artworks depicting life under occupation.
The most recent contribution from Banksy in this regard has been a small art piece that was displayed inside the hotel last Christmas, called ‘The Scar of Bethlehem.’ It depicts a nativity scene (the birth of Jesus) set to the backdrop of the concrete barrier, with a bullet hole in it resembling a star and has garnered praise from many western news outlets as a symbol of solidarity with Palestinian suffering.
Posters, and innovative methods of distributing the same, are another form of artistic protest. These range from the posters by various artists published in a leftist French newspaper, meant to be cut out and pasted on walls by the public; to the Turkish graphic design professors using public walkways to exhibit posters in solidarity with Gaza.
Posters have also sprung up in various places across the world, including Israel, calling for active demonstrations against Israel’s plans to annex the West Bank. All of the mentioned posters continue to be collected in the digital archives of the Palestine Poster Project.
Another popular collection dates back to 1970s Australia, circulated by Ali Kazak, a Palestinian ambassador, called “landscape posters” for their focus on Palestinian land. Many posters utilised symbols such as traditional Palestinian dresses, fruits such as olives and oranges, and keys, which refer to the refugees.
Some of the older art from around the 1970s focused on pre-war Palestinian life and culture, while the newer art takes a multi-media form through photographs, science fiction and films. Similarly, many murals can be found surrounding Land Day, which serves as a reminder of a massacre in 1976 in response to a protest.
Artistic symbolism also often uses the concept of Sumud, which means resilience in Arabic, and is used to refer to a “sense of rootedness” to Palestinian land.
Music also found its voice as a form of self-expression and resistance. In 2018, music platform Boiler Room hosted Boiler Room Palestine for the first time. The show featured a diversity of Palestinian artists from Palestinian and Israeli territories. The crew for the show had to enter Palestine through Israel, giving them a small taste of the limitation of movement for Palestinians.
Palestinian art continues to grow as a form of self-expression, as a form of resistance to Israeli policies, and as forms of cultural history in an endeavour to keep Palestinian spirits and identity alive as their lives get shrunk into smaller and smaller pieces of land.
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Detecting The Ultra-High Energy Cosmic Rays With Smartphones
Smartphones have become the most commonplace objects in our daily lives. The unimaginable power that we hold in our hands is unrealized by most of us and, more importantly, untapped. Its creativity often gets misused but one can only hope that it’s fascinating abilities would be utilized. For example, did you know that the millions of phones around the globe can be connected to form a particle detector? The following article covers the CRAYFIS (Cosmic RAYs Found in Smartphones) phone-based application developed by the physicists from the University of California—Daniel Whiteson, Michael Mulhearn, and their team. CRAYFIS aims to take advantage of the large network of smartphones around the world and detect the cosmic or gamma rays bursts which enter the Earth’s atmosphere almost constantly.
What Are Cosmic Rays?
Cosmic rays are high velocity subatomic particles bombarding the Earth’s upper atmosphere continuously. Cosmic ray bursts have the highest energy compared to all forms of electro-magnetic radiation. When we say ultra-high energy particles (energy more than 10<sup>18</sup> eV), we mean two million times more energetic than the ones that can be produced by the particle colliders on Earth. These rays are thought to be more powerful than typical supernovae and can release trillions of times more energy than the Sun. They are also highly unpredictable as they can enter Earth’s atmosphere from any direction and the bursts can last for any period of time ranging from a few thousand seconds to several minutes.
Despite many theoretical hypotheses, the sources of these ultra-high energy cosmic rays are still a mystery to us even after many decades of their discovery. These rays were initially discovered in the 1960’s by the U.S. military when they were doing background checks for gamma rays after nuclear weapon testing. Cosmologists suggest that these bursts could be the result of super massive stars collapsing - leading to hypernova; or can be retraced to collisions of black holes with other black holes or neutron stars.
How Do We Detect Them?
When the high-energy particles collide with the Earth’s atmosphere, the air and the gas molecules cause them to break apart and create massive showers of relatively low-energy particles. Aurora borealis i.e., the Northern and the Southern lights are the lights that are emitted when these cosmic rays interact with the Earth’s magnetic field. Currently, these particles are hitting the Earth at a rate of about one per square meter per second. The showers get scattered to a radius of one or two kilometers consisting mostly of high-energy photons, electrons, positrons and muons. But the fact that these particles can hit the Earth anytime and anywhere is where the problem arises. Since the Earth has a massive area, it is not possible to place a detector everywhere and catch them at the exact moment.
Energetic charged particles known as cosmic rays hit our atmosphere, where they collide with air molecules to produce a shower of secondary particle | Source: CERN
Detecting such a shower requires a very big telescope, which logically means a network of individual particle detectors distributed over a mile or two-wide radius and connected to each other. The Pierre Auger Observatory in South America is the only such arrangement where 1,600 particle detectors have been scattered on 3,000 square kilometers of land. But the construction cost of the same was about $100 million. Yet, only a few cosmic ray particles could be detected using this arrangement. How do we spread this network around the Earth?
In addition to being cost-effective, such a setup must also be feasible. The Earth’s surface cannot possibly be dotted with particle detectors which cost huge fortunes. This is where smartphones come into the picture.
Detecting The Particles Using Smartphones
Smartphones are the most appropriate devices required to solve the problem. They have planet wide coverage, are affordable by most people and are being actively used by more than 1.5 billion users around the planet. Individually, these devices are low and inefficient; but a considerably dense network of such devices can give us a chance to detect cosmic ray showers belonging to the highest energy range.
Previous research has shown that smartphones have the capability of detecting ionizing radiation. The camera is the most sensitive part of the smartphone and is just the device required to meet our expectations. A CMOS (Complementary Metal Oxide Semiconductor) device is present in the camera- in which silicon photodiode pixels produce electron-hole pairs when struck by visible photons (when photons are detected by the CMOS device, it leaves traces of weakly activated pixels). The incoming rays are also laced with other noises and interference from the surroundings. Although these devices are made to detect visible light, they still have the capability of detecting higher-energy photons and also low-ionizing particles such as the muons.
A screenshot from the app which shows the exposure time, the events- the number of particles recorded and other properties
To avoid normal light, the CRAYFIS application is to be run during nighttime with the camera facing down. As the phone processor runs the application it collects data from its surroundings using a camera as its detector element. The megapixel images (i.e., the incoming particles) are scanned at a speed of 5 to 15 frames per second, depending on the frame-processing speed of the device. Scientists expect that signals from the cosmic rays would occur rarely, i.e., around one in 500 frames. Also, there is the job of removing background data. An algorithm was created to tune the incoming particle shower by setting a threshold frequency at around 0.1 frames per second. Frames containing pixels above the threshold are stored and passed to the second stage which examines the stored frames, saving only the pixels above a second, lower threshold.
The CRAYFIS app is designed to run when the phone is not being used and when it is connected to a power source. The actual performance would be widely affected by the geometry of the smartphone’s camera and the conditions in which the data is being collected. Further, once the application is installed and is in the operating mode, no participation is required from the user, which is required to achieve wide-scale participation. When a Wifi connection is available the collected data would be uploaded to the central server so that it could be interpreted.
There is much complicated math used to trace back the information collected from the application. The most important parameters for the app are the local density of incoming particles, the detection area of the phone and the particle identification efficiency. These parameters are used to find the mean number of candidates (photons or muons) being detected. Further, the probability that a phone will detect no candidates or the probability that a phone will detect one or more candidates is given by Poisson distribution. The density of the shower is directly proportional to the incident particle energy with a distribution in x and y sensitive to the direction in which the particle came from. An Unbinned Likelihood (it is the probability of obtaining a certain data- in this case the distribution of the cosmic rays including their energy and direction, the obtained data is arranged into bins which are very, very small) analysis is used to determine the incident particle energy and direction. To eliminate background interference, a benchmark requirement has been set that at least 5 phones must detect and register a hit to be considered as a candidate.
It is impossible to express just how mind-blowing this innovation is. As the days pass, Science and Technology around us keep on surprising us and challenge us to rack our brains for more and more unique ways to deal with complex problems. The CRAYFIS app is simply beautiful and it would be a dream-come-true to the scientists if the project works out and we are able to detect these high energy, super intimidating cosmic rays with smartphones from our backyard.
Further Reading
The paper by Daniel Whiteson and team can be found here.
An exciting book “We Have No Idea” by Daniel Whiteson and cartoonist Jorge Cham can be found here.
