What happens if you don’t switch your smartphone to airplane mode during flight 

Here is what really happens if you don’t put your smartphone into flight mode/airplane mode when flying

You may have traveled a lot by air and may have been told and warned to switch your smartphone to flight mode or airplane mode. Have you ever wondered why you are asked by the flight attendants on board to switch your devices to airplane mode during transit? Did you ever imagine what would happen if you didn’t put your smartphone on airplane mode when you are up in the air?
Most of us may feel it is unnecessary to switch to airplane mode during flight. Some of us even feel that doing so is a waste of time as it achieves nothing as it doesn’t interfere with plane’s electrical and telecommunication systems and is not a matter of life and death, some think it can cause occasional disturbance not leading to a crash for sure.
So, what is the truth? Let’s find out what exactly happens when passengers or crew don’t switch their phones to airplane mode during a flight!

There is no evidence that signals from passengers’ electronic devices have ever caused a plane to malfunction and crash. The reason for prospective safety concerns is due to the fact that when you are more than 10,000 feet in the air, your cell phone signal bounces off multiple towers and sends out a stronger signal. This is something that might congest the networks on the ground. But, there has never been a case of a cell phone causing a plane to crash.
Also, if you leave it on, it can annoy pilots and cause an unpleasant sound for air traffic controllers. A smartphone’s radio emissions can be very strong, up to 8W, which cause this noise due to parasitic demodulation. However, in a worst case scenario, repeated interference from mobiles could cause the crew to miss a crucial radio call from air traffic control.

In a blog post for Airline Updates, a pilot said that transmitting mobiles can cause audible interference on an aircraft’s radios, but it is rare. He said: “Your phone will probably annoy a few pilots and air traffic controllers. But, most likely, not badly enough for them to take action against you if that’s what you want to know.”
“You may have heard that unpleasant noise from an audio system that occasionally happens when a mobile phone is nearby. I actually heard such noise on the radio while flying. It is not safety critical, but is annoying for sure.”
Those problems are something like the noise that can be heard when a smartphone rings near to a speaker: a slow, percussive thumping. But instead of coming out of a speaker it can be heard through the headsets that are worn by pilots.
Further, he also continues by saying that if 50 people on the plane did not turn their smartphone onto flight mode, it would cause a lot of “radio pollution.”

An engineer named ‘Coenraad Loubser’ said on Quora: “To compound matters, the weaker the signal your cell phone picks up from the tower, the more it amplifies its signal to try and get a response (and the more battery it uses). Planes with onboard cell coverage, allow your phone to communicate using very low power, or Wi-Fi. When you put your phone in Airplane mode, the GSM/3G Radio inside your phone is completely disabled and you can still use the phone for other functions.”
So, when you are flying next time, it is advisable to stick to the rules onboard.

By Kavita Iyer

China Beats US On Supercomputer List

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Here are the three reasons China can now claim the title of having built the world’s fastest supercomputer.

In 2001, China had no presence on the list of the top 500 supercomputers in the world. Today, the world's most populous country has the most supercomputers on the list, including the world's fastest — and for the first time ever it no longer relies on chips made by U.S. companies.

The Sunway TaihuLight supercomputer based at the state-funded Chinese Supercomputing Center in the city of Wuxi, Jiangsu province, a two-hour drive from Shanghai. China already held the top spot on the list of fastest supercomputers with the Tianhe-2, but that featured processors built by Intel, a U.S. company.

However, a chip built by the Shanghai High Performance IC Design Center called SW26010 is capable of achieving 125.4 petaflops (Pflop/s). That means it can carry out more than 125 quintillion calculations per second. The SW26010 is comprised of more than 10 million processing cores, and to put its performance in context, Tianhe-2 topped the list in 2015 with a performance of 33.86 Pflops/s.

“As the first number one system of China that is completely based on homegrown processors, the Sunway TaihuLight system demonstrates the significant progress that China has made in the domain of designing and manufacturing large-scale computation systems,” Guangwen Yang, director of the Chinese Supercomputing Center, told TOP500 News.

The supercomputer will be used for research and engineering work in areas such as climate, weather and earth systems modeling, life science research, advanced manufacturing and data analytics.

The list of the world's fastest 500 supercomputers is compiled by research organization TOP500, and the list this year shows that for the first time China has more supercomputers (167) on the list than the U.S. (165), with Japan a distant third with just 29.

So how has China gone from supercomputer nobody to powerhouse in such a short time?

1. China's Government 

China's government wants to lessen (and where possible eradicate) the dependence on overseas technology, specifically technology designed and built in the U.S. To do this, it has invested heavily in research and development such as the National Supercomputing Center to develop homegrown solutions.

According to Wall Street research firm Sanford C. Bernstein, the country buys half of all the semiconductors produced in the world, but it doesn't have a single domestic chipmaker among the world's biggest. For this reason, China's government has told local media that it will pledge 1 trillion yuan ($152 billion) to help create a Chinese chip industry by 2025.

The Sunway TaihuLight is a major milestone on the road to creating this industry.

2. U.S. Embargo

In addition to being spurred by its own government, the Chinese technology industry was given a push by the U.S. government, too. In April 2015, the U.S. blocked high-end processors, such as Intel's Xeon Phi chips, from being sold to a number of Chinese supercomputing centers. The U.S. Department of Commerce never publicly said why the embargo was in place, but the rules state certain items can be blocked if there is "a significant risk of being or becoming involved in activities that are contrary to the national security or foreign policy interests of the United States."

The move precipitated a more concerted effort in China to develop and manufacture such chips domestically.

3. Money

While the market for supercomputing chips is not huge, there is a huge market for computer chips in general, and by showing that it can produce processors capable of matching, and beating, those on offer from Intel and IBM, China is now in a position to begin marketing its homegrown solutions to server manufacturers and data centers — a market that is currently dominated by Intel. 

Companies like Intel and Qualcomm know just how important the Chinese market is and are aware of the risks a well-funded domestic chipmaker could have on their bottom lines. To that end both companies have invested heavily in China, partnering with local companies to bring manufacturing to the country.

Universe expanding faster than expected

By Robert Sanders

Astronomers have obtained the most precise measurement yet of how fast the universe is expanding, and it doesn’t agree with predictions based on other data and our current understanding of the physics of the cosmos.

A Hubble Space Telescope image of the galaxy UGC 9391, one of the galaxies in the new survey. UGC 9391 contains the two types of stars – Cepheid variables and a Type 1a supernova – that astronomers used to calculate a more precise Hubble constant. Click on the image to see the red circles that mark the locations of Cepheids. The blue “X” denotes the location of supernova 2003du, a Type Ia  Hubble Space Telescope. The observations for this composite image were taken between 2012 and 2013 by Hubble’s Wide Field Camera 3. (Image by NASA, ESA, and A. Riess [STScI/JHU])

The discrepancy — the universe is now expanding 9 percent faster than expected — means either that measurements of the cosmic microwave background radiation are wrong, or that some unknown physical phenomenon is speeding up the expansion of space, the astronomers say. “If you really believe our number — and we have shed blood, sweat and tears to get our measurement right and to accurately understand the uncertainties — then it leads to the conclusion that there is a problem with predictions based on measurements of the cosmic microwave background radiation, the leftover glow from the Big Bang,” said Alex Filippenko, a UC Berkeley professor of astronomy and co-author of a paper announcing the discovery.
“Maybe the universe is tricking us, or our understanding of the universe isn’t complete,” he added.
The cause could be the existence of another, unknown particle — perhaps an often-hypothesized fourth flavor of neutrino — or that the influence of dark energy (which accelerates the expansion of the universe) has increased over the 13.8 billion-year history of the universe. Or perhaps Einstein’s general theory of relativity, the basis for the Standard Model, is slightly wrong.
“This surprising finding may be an important clue to understanding those mysterious parts of the universe that make up 95 percent of everything and don’t emit light, such as dark energy, dark matter and dark radiation,” said the leader of the study, Nobel laureate Adam Riess, of the Space Telescope Science Institute and Johns Hopkins University, both in Baltimore. Riess is a former UC Berkeley post-doctoral fellow who worked with Filippenko.
The results, using data from the Hubble Space Telescope and the Keck I telescope in Hawaii, will appear in an upcoming issue of the Astrophysical Journal.
Afterglow of Big Bang

A few years ago, the European Space Agency’s Planck observatory — now out of commission — measured fluctuations in the cosmic background radiation to document the universe’s early history. Planck’s measurements, combined with the current Standard Model of physics, predicted an expansion rate today of 66.53 (plus or minus 0.62) kilometers per second per megaparsec. A megaparsec equals 3.26 million light-years.

Astronomers used the Hubble Space Telescope to measure the distances to a class of pulsating stars called Cepheid variables to calibrate their true brightness, so that they could be used as cosmic yardsticks to measure distances to galaxies much farther away. This method is more precise than the classic parallax technique. (Image courtesy of NASA, ESA, A. Feild [STScI], and A. Riess [STScI/JHU])

Previous direct measurements of galaxies pegged the current expansion rate, or Hubble constant, between 70 and 75 km/sec/Mpc, give or take about 5−10 percent — a result that is not definitely in conflict with the Planck predictions. But the new direct measurements yield a rate of 73.24 (±1.74) km/sec/Mpc, an uncertainty of only 2.4 percent, clearly incompatible with the Planck predictions, Filippenko said. The team, several of whom were part of the High-z Supernova Search Team that co-discovered the accelerating expansion of the universe in 1998, refined the universe’s current expansion rate by developing innovative techniques that improved the precision of distance measurements to faraway galaxies.
The team looked for galaxies containing both a type of variable star called a Cepheid and Type Ia supernovae. Cepheid stars pulsate at rates that correspond to their true brightness (power), which can be compared with their apparent brightness as seen from Earth to accurately determine their distance and thus the distance of the galaxy. Type Ia supernovae, another commonly used cosmic yardstick, are exploding stars that flare with the same intrinsic brightness and are brilliant enough to be seen from much longer distances.
By measuring about 2,400 Cepheid stars in 19 nearby galaxies and comparing the apparent brightness of both types of stars, the researchers accurately determined the true brightness of the Type Ia supernovae. They then used this calibration to calculate distances to roughly 300 Type Ia supernovae in far-flung galaxies.
“We needed both the nearby Cepheid distances for galaxies hosting Type Ia supernovae and the distances to the 300 more-distant Type Ia supernovae to determine the Hubble constant,” Filippenko said. “The paper focuses on the 19 galaxies and getting their distances really, really well, with small uncertainties, and thoroughly understanding those uncertainties.”
Calibrating Cepheid variable stars

Using the Keck I 10-meter telescope in Hawaii, Filippenko’s group measured the chemical abundances of gases near the locations of Cepheid variable stars in the nearby galaxies hosting Type Ia supernovae. This allowed them to improve the accuracy of the derived distances of these galaxies, and thus to more accurately calibrate the peak luminosities of their Type Ia supernovae.
“We’ve done the world’s best job of decreasing the uncertainty in the measured rate of universal expansion and of accurately assessing the size of this uncertainty,” said Filippenko, “yet we find that our measured rate of expansion is probably incompatible with the rate expected from observations of the young universe, suggesting that there’s something important missing in our physical understanding of the universe.”
“If we know the initial amounts of stuff in the universe, such as dark energy and dark matter, and we have the physics correct, then you can go from a measurement at the time shortly after the Big Bang and use that understanding to predict how fast the universe should be expanding today,” said Riess. “However, if this discrepancy holds up, it appears we may not have the right understanding, and it changes how big the Hubble constant should be today.”
Aside from an increase in the strength with which dark energy is pushing the universe apart, and the existence of a new fundamental subatomic particle – a nearly speed-of-light particle called “dark radiation” – another possible explanation is that dark matter possesses some weird, unexpected characteristics. Dark matter is the backbone of the universe upon which galaxies built themselves into the large-scale structures seen today.
The Hubble observations were made with Hubble’s sharp-eyed Wide Field Camera 3 (WFC3), and were conducted by the Supernova H0 for the Equation of State (SHOES) team, which works to refine the accuracy of the Hubble constant to a precision that allows for a better understanding of the universe’s behavior.
The SHOES Team is still using Hubble to reduce the uncertainty in the Hubble constant even more, with a goal to reach an accuracy of 1 percent. Telescopes such as the European Space Agency’s Gaia satellite, and future telescopes such as the James Webb Space Telescope (JWST), an infrared observatory, and the Wide Field Infrared Space Telescope (WFIRST), also could help astronomers make better measurements of the expansion rate.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C. The W. M. Keck Observatory in Hawaii is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA.

Filippenko’s research was supported by NASA, the National Science Foundation, the TABASGO Foundation, Gary and Cynthia Bengier and the Christopher R. Redlich Fund.