It creates an infinitely curved region of space-time, from which nothing can escape, not even light. Do black holes rotate? This is an interesting but not so simple question that I received in one of my recent lectures. To answer it completely and accurately, we need a clear understanding of the very verifiable properties of black holes as well as about the nature of rotation. To date, the concept of rotating black holes is not new. In fact, every object in the universe, once having a mass large enough to be spherical, will also have a rotation. Since mass exerts gravity, every object tends to compress itself – because its parts attract each other. For small masses, this gravitational compressive force – commonly known as centripetal gravity – is so small that it cannot exert any effect on the object, because it is simply an intermolecular force of cohesion. substance – especially solids – is much larger than it is. But with very large masses, on the other hand, the force of gravity is so great that matter will rearrange until it becomes spherical. That is, the state in which the force of gravity directed at the center of the object from all directions is equal to each other. That’s how every object as large as a planet or a star gets its spherical shape. At the same time, when there is such a large mass, another problem arises, and also related to gravity. Since no single star or planet is perfectly uniform, in fact the gravitational forces in their different regions are unequal. This difference is the main reason they oscillate, and hence the rotation. Thus, all large objects in the universe rotate because of their own gravity. What about black holes? The most common types of black holes known to scientists today are stellar-mass black holes. It is formed from the late-life contraction of the cores of massive stars. These stars are usually at least 8 to 10 times the mass of the Sun. Towards the end of their lives, their cores shrink very rapidly because the fusion reaction no longer produces enough energy to resist the contraction of that enormous mass. This sudden contraction causes an explosion that is considered one of the most violent events in the universe” supernova explosion. This explosion tore apart the stellar shell that was previously in the state of a red supergiant. The remaining core of the star shrinks and collapses to become a black hole. All stars rotate on their own axis (our Sun, for example, has a rotation period of more than 25 days). It is not difficult to speculate that something formed from a rotating stellar core would also have to rotate, because that momentum is simply still there. The same is probably true of supermassive black holes – black holes with masses ranging from hundreds of thousands to billions of times the Sun, located at the center of most galaxies ever observed. In fact, when the first image of a black hole was released in 2019, scientists were able to see the spirals of the accretion disk surrounding the black hole. It shows that the giant accretion disk is rotating, not fixed. Just like the fact that all the stars in each galaxy are constantly moving around the center of the galaxy (for example, our Sun takes about 230 million years to complete one full circle around the center of the Milky Way). Two things need to be clarified before concluding that the black hole rotates on its own The entire initial mass of the black hole – in theory – is packed into an extremely small singularity. It is so small that it can mathematically be considered sizeless. That singularity has a certain radius (Schwarzchild radius) known as the black hole’s event horizon, but it is just a region of pure space-time, not an object like it has a surface. like a star or a planet. As such, it is difficult to consider something with no dimensions, or a boundary without a surface, to be rotating, since there is simply no alternate motion of points to a particular surface. No radiation comes out from within the event horizon, which also means that all information inside a black hole is unknown. If matter were indeed crushed and completely collapsed into a single point, the space within the event horizon could itself be a place of absolute uniformity, i.e. no rotation would occur due to the difference. interesting. With these two points in mind, don’t forget that what we see spinning is itself just the accretion disk surrounding the black hole. Of course, one can also calculate the rotational speed of an accretion disk based on its mass when taking into account as well as when not taking into account the presence of a black hole at the center, from which to compare and predict. It looks like the black holes in those places are spinning very fast. Even so, given that we don’t know anything about what lies within the event horizon, or even something specific happening at its very edge, concluding that black holes are indeed rotate or not and how fast they rotate is still too early. Likewise, the charge of a black hole is also a purely theoretical concept and is calculated from solving Einstein’s equations. There is no way for us to verify if an electric charge really exists after being swept inside the black hole’s event horizon. In the future, to know more about this information, we will need to look forward to new generations of telescopes and new methods to image and track more black holes with much greater detail. compared to what there are today.

As noted by Fox News, NASA’s rocket launch window opened at 20:04 and the rocket launched at 20:36 on the same day. About 10 minutes after launch, the Black Brant XII rocket ejected barium vapor at an altitude of about 350-400km above the Atlantic Ocean, just north of Bermuda and about 870-900km from Wallops. The barium vapor from the NASA rocket is not harmful to the environment and has formed two blue-violet clouds that can be seen across the East Coast for about 30 seconds. However, clouds prevented the launch from being viewed with the naked eye. “This is the last date NASA intends to authorize a rocket launch from Wallops. The vocal rocket was originally scheduled to launch on May 8 but has been postponed several times a week,” Fox News wrote and reported. For further information, the Black Brant XII rocket launched during NASA’s KiNet-X mission – designed to study how energy and momentum is transported between different regions of space with a magnetic connection. The Black Brant XII missile is a 4-stage rocket. Peter Delamere, KiNET-X principal investigator from the University of Alaska Fairbanks said: “The aurorae – also known as the north pole or pole light, is formed when particles in the ‘near universe’ of the Earth’s ‘near space’. Earth interacts with the atmosphere Electrons in Earth’s space environment and in the solar wind are relatively low in energy, however, the aurora is produced by very high energy electrons. Vapors emitted from the rocket’s payload will generate magnetic interference and potentially energized electrons.KiNET-X consists of a single rocket launch carrying seven separable payloads – equipment primary diagnostic device, along with four small sideloads and clouds of barium vapor set to release from two additional, larger payloads”. Beautiful performance Analyzing further, meteorologist Katie McGraw told News 5 that when the launch happened, people in Northeast Ohio could see it thanks to clear skies. NASA called the May 16 launch of the Black Brant XII rocket a “beautiful display” and couldn’t have written a better story. Katie McGraw further revealed that the Black Brant XII rocket was used for the mission to explore energy transport in space. Black Brant is the result of research at the Canadian Arms Research and Development Facility (CARDE) in the 1950s into the nature of the upper atmosphere as part of ongoing research into anti-missile systems. ballistic fire and long-range communications. The launch took place on May 16 after a week of waiting. In 1957, CARDE contracted with Bristol to produce a simple rocket fuselage, called the Propulsion Test Vehicle, for high-powered solid fuel studies. Albert Fia’s design is quite heavy, as it is designed to accommodate a wide range of engine burn times, propellant loads and launch angles well suited to its role as a test vehicle for development. ABM system. The first test flight took place just two years later. CARDE’s attention then turned to long-distance communications, and they found the propulsion test vehicle system useful as a locating missile. To better suit this role, Bristol modified the design to be lighter and more suitable for the Black Brant missile role. CARDE has launched several Black Brant rockets over the years with the original Black Brant I design able to carry a payload of 68 kg to an altitude of 150 km and fly for the first time in October 1960. The missile’s design emphasizes payload reliability and range. There are 12 versions of the Black Brant and the Black Brant XII is a four-stage sonic launcher manufactured in 1995. The missile was first launched from the Andoya rocket range off the northwest coast of Norway and caused an explosion also known as the fear of Black Brant. This incident has put Russia’s nuclear forces on high alert, fearing a high-altitude nuclear strike could blind Russia’s radar, and Russia’s Cheget “nuclear briefcase” has been put on high alert. sent to Russian President Boris Yeltsin, who must then decide whether to launch a retaliatory nuclear strike against the United States. This is the first and only known incident to date where any nuclear-weapon country has activated its nuclear briefcase and prepared for an attack. On September 19, 2009, a Black Brant XII rocket launched to study the clouds caused calls from eastern North America reporting “strange lights in the sky”. NASA reported that the light came from an artificial noctilucent cloud formed by the exhaust particles of the rocket’s fourth stage at an altitude of about 278 km.

At present, China Mobile in Jiangsu has basically achieved continuous 5G network coverage in 13 cities, urban areas and counties in the province, contiguous coverage of key towns and villages, coverage of key traffic trunk lines, coverage of key business districts and scenic spots, and 5G network coverage of key units and places. The number of base stations exceeds 42,000. In addition, in order to meet the needs of establishing a new generation of high-quality home broadband network and supporting smart home information services, China Mobile actively responded to the country’s call for “dual G and dual promotion”, and vigorously promoted the development of home broadband access capabilities in the Yangtze River Delta to gigabit. According to the “plan” issued by the Ministry of Industry and Information Technology, “At the end of 2021, the gigabit optical fiber network will have the capacity to cover 200 million households, and the gigabit broadband users will exceed 10 million.” Focusing on Jiangsu, China Mobile’s gigabit broadband has covered the province. Nearly 90,000 communities, 35 million households, to build a high-quality Gigabit network leading the province. In the recent “Mobile Strong Innovation 5G Helps Growth” Jiangsu Regional Tour, the reporter walked into Jiangsu Mobile to visit and learn about the current development of 5G integration in Jiangsu, and physically visited Jiangsu’s wisdom construction results. 5G financial industry boosts regional economic development Taking 5G Rongbaiye as an example, Jiangsu Mobile has created 100 high-quality 5G “model houses” and promoted more than 800 5G projects: In the 5G+ smart factory of Changzhou Jingyan Technology, the product inspection speed of AI quality inspection robots is faster than that of manual labor. Nearly 10 times; the country’s first smart warehousing project integrating 5G industrial modules landed in Suzhou, and its work efficiency was increased by 30-50% compared to warehousing in a non-5G network environment; 5G+ mind-brain built on mobile 5G network, cloud computing and other technologies The vascular disease Internet diagnosis and treatment and rehabilitation management platform has innovated the medical service model of “5G real-time monitoring, artificial intelligence-assisted diagnosis, cloud platform online diagnosis and treatment, and chronic disease tracking management”; the first batch of the country and the only new 5G infrastructure in the Yangtze River Delta region Collaborative project-Suzhou 5G Internet of Vehicles city-level verification and application, will achieve more than 200,000 connected users and 150 application scenarios… In addition, according to the relevant person in charge, in order to support the transformation of industrial informatization, Jiangsu Mobile established the DICT Ecological Alliance in December 2020 and launched the “9 one platform” plan including smart cities, industrial Internet, smart healthcare, smart education, etc. , To provide partners with one-stop technical support based on 5G private network services such as the Internet of Things, big data, blockchain, and cloud computing. Among them, the “Nanjing Jiangbei New Area Kunpeng Digital Platform” based on the OneCity smart city platform was successfully selected as one of the top ten model projects for China Mobile’s new smart city. In Jiangsu’s transformation with digital intelligence as the means and economic transformation and upgrading as the goal, the Jiangsu 5G Industry Alliance has contributed a lot. As the chairman unit, Jiangsu Mobile makes full use of its own network and resource advantages to create a new digital intelligence ecosystem with industry partners. It is reported that at present, the member units of the industry alliance have reached 626, covering the upstream and downstream of the 5G industry chain, including industrial Internet, transportation, medical care, education and other industries. What’s more gratifying is that, with the support of the industry alliance, Jiangsu won 23 awards in the national finals of the 2020 (third) “Bloom Cup” 5G Application Contest, of which Jiangsu Mobile accounted for 18, ranking the top in all provinces. Create inclusive and shared communication and information services In April 2020, the National Development and Reform Commission and the Ministry of Transport issued the “Higher Quality Integrated Development Plan for Transportation in the Yangtze River Delta”, which proposed to focus on the Shanghai metropolitan area and the Nanjing, Hangzhou, Hefei, Suzhou, Wuxi, and Ningbo metropolitan areas. Inter-city railways, urban rail transit, and urban expressways are the backbone to create a one-hour commuter circle in the metropolitan area. The emergence of the mobile blue card just caters to this traffic development trend. The reporter learned that China Mobile has launched a small blue card public transport card service, combined with the mobile phone’s NFC function, and loaded the transportation card application into the SIM card. The mobile phone can be swiped even if the phone is out of power or black. It can be used in Beijing, Guangzhou, Hangzhou, and the entire Jiangsu province. It is used in more than 300 cities across the country, and the success rate of credit card swiping in the Yangtze River Delta (Jiangsu, Zhejiang, Shanghai and Anhui) is 100%. Not only that, in the field of transportation hubs, China Mobile has achieved full coverage of metro lines in the entire province of Jiangsu, covering 20 metro lines in Nanjing, Suzhou, Wuxi, Changzhou, Xuzhou and other cities. At the same time, China Mobile 5G has covered 57 There are a large passenger flow high-speed railway station, as well as 54 high-speed toll stations and service areas, the entire Shanghai-Nanjing Expressway, key bus stations, and airports. Layout the new carrier of the digital economy in the Yangtze River Delta According to reports, in order to accelerate the full penetration of mobile communication technology from the consumer side to the production side, and to promote digital intelligence technology to empower thousands of industries, China Mobile is empowering the information hub of the Yangtze River Delta and the research and development innovation highland, creating a new carrier for the digital economy in Jiangsu. Promote the construction and operation of data centers. At present, China Mobile Yangtze River Delta (Nanjing) Data Center, China Mobile Yangtze River Delta (Suzhou) Data Center, and China Mobile (Wuxi) Data Center have all passed IDC computer room rating and have been awarded the title of China Mobile’s 2020 “Diamond Five-Star Data Center” . “These data centers are used as computing power and data bearing platforms to realize the security control of the entire chain of data collection, transmission, storage, and use, and build a more comprehensive, higher-quality, and more valuable big data service system from people and things. , Which can provide users in the Yangtze River Delta with professional, stable, and customized cloud computing services, and help the integrated and high-quality development of the Yangtze River Delta.” said Jiangsu Mobile staff. In addition, in order to optimize the layout of scientific research, face the front line of technology and the market, explore the establishment of new R&D institutions, in terms of systematically promoting innovation, in order to implement the national innovation-driven development strategy, China Mobile has deployed scientific and technological innovation R&D carriers in the Yangtze River Delta region and integrated into the national New District-Nanjing Jiangbei New District master plan, the establishment of China Mobile Yangtze River Delta (Nanjing) Science and Technology Innovation Center, China Mobile Zijin (Jiangsu) Innovation Research Institute, together with Southeast University, Zijinshan Laboratory and other key universities and research institutes, fully integrate Jiangsu The provincial scientific and technological innovation resource advantage, organize and promote the Internet of Things, cloud computing, big data, blockchain and other technology research and product application development, and accelerate the cultivation of core competitiveness.

The sea tours are the most chosen by tourists during the holidays April 30 and 1-5. In the photo : The cable car route across Hon Thom sea starts from An Thoi station and ends at Hon Thom (Phu Quoc city, Kien Giang province). Photo: Quynh Danh Many incentives and attractive discounts This year, the 4-day holiday season of April 30 and May 1 is a favorable opportunity for tourism businesses and destinations to attract tourists, increasing revenue in the context of the well-controlled Covid-19 epidemic. in water. To anticipate this tourist season, from the beginning of March 2021, airlines and many travel agencies have introduced attractive stimulus products, suitable to the trends and psychology of tourists. In addition to some flights with “hot” prices every day, such as the one from Hanoi to Nha Trang (Khanh Hoa province), Phu Quoc (Kien Giang province), Con Dao (Ba Ria – Vung Tau province), the Airlines Vietnam Airlines, Vietjet Air, Bamboo Airways, and Pacific Airlines also reserve low-priced tickets in some routes: Hanoi to Quy Nhon (Binh Dinh province), Da Nang with less than 1 million VND / leg; Hanoi – Ho Chi Minh city about 2 million VND / leg. From the travel perspective, Vietravel Tourism Company launched many resort and discovery travel packages with “hitting the floor” price from only 699 thousand VND; Tour Da Nang – Hanoi – Ha Giang 4 days, 3 nights cost 5.39 million VND / person. VietSense Tourism Company introduces tours from Hanoi or Ho Chi Minh City to Con Dao (Ba Ria – Vung Tau province), Da Nang – Hoi An (Quang Nam province), Phu Quoc (Kien Giang province) , Moc Chau (Son La province) … has a discount from 10% to 25%. Flamingo Redtours Travel Company introduces domestic road tour priced from only 1.69 million / person, air tour priced from 8.29 million / person. Evaluation of tourism activities on the holidays April 30 and 1-5, Director of Vietravel Travel Company – Hanoi Branch Pham Van Bay said, as of the end of March 2021, more than 50% of the total 15,000 air tickets that Vietravel Tourism Company reserved to serve customers during the holidays have been sold. Meanwhile, Chairman of the Hanoi Travel Association, Director of Hanoitourist Travel Company Phung Quang Thang, informed that the number of visitors calling or booking online is quite a lot, up from 50% to 100% over the same period last year. . It is forecasted that the number of tourists who ordered tours will increase in the coming days. Director of Vietrantour Tourism Company Nguyen Thi Huyen said that the number of tourists increased and the demand for service quality also increased. And the director of VietSense Tourism Nguyen Van Tai information, marine tourism routes, such as Quy Nhon (Binh Dinh province), Nha Trang (Khanh Hoa province), Phu Quoc (Kien Giang province), Ha Long (Quang province). Ninh) … is still the most chosen by tourists. In addition, many people find information about routes to the East – Northwest, Central Highlands, and West areas. Tourists experience the product of caravan tourism to explore the Northwest of VGreen Club (Hanoi Travel Association). “Leverage” to restore the market According to the travel agencies, due to the impact of the Covid-19 epidemic, tourists do not book tours early, often close to the new registration date, so the holiday tourism activities on April 30th, 1-5 and beyond, summer tourism is subject to change. Many new travel trends such as self-sufficient travel, small group travel, family travel or caravan travel (self-driving) will “take the throne”. Standing Vice Chairman of the Vietnam Tourism Association Vu The Binh assessed that the tourism demand stimulus for the holidays of April 30 and May 1-5 will be “leverage” to regain the growth momentum for the tourism industry in the year. now on. “Psychology of tourists wanting to travel again is clear. The units need to step up their stimulus program, improve service quality, increase product experience to attract more customers, get growth momentum for summer tourism and the rest of the year ”, Mr. Vu The Binh said. Tourism activities across the country in general and Hanoi capital in particular are showing the bustle and excitement again with many promotional activities and events attracting tourists. Notably, the festival of tourism and culinary culture in Hanoi 2021 takes place from April 16 to 18; Opening ceremony of the National Tourism Year 2021 on April 20 in Ninh Binh province; Vietnam International Tourism Fair – VITM Hanoi 2021 took place in May … In order to maintain the stability of the domestic tourism market after the stimulus phase, proceed to prepare conditions to welcome international visitors, according to the Director of the Hanoi Department of Tourism Dang Huong Giang, in addition to strengthening the promotion stage, To build new products, tourism agencies need to pay attention to retraining tourism human resources, attracting back the workforce that has quit their jobs due to the effects of the Covid-19 epidemic. And the Minister of Culture, Sports and Tourism Nguyen Van Hung noted that localities and tourism business units need to give prominence to the prevention and control of Covid-19 epidemic in operations, in compliance with regulations on prevention and combat. according to the recommendations and requests of the Ministry of Health as well as the Ministry of Culture, Sports and Tourism. “Tourism is the industry most clearly affected by the Covid-19 influence. Just appear cases in the community, tourism activities are stopped immediately, so the request for epidemic prevention and control must be of primary concern ”, emphasized Minister Nguyen Van Hung.