The speed of light (more generally, the speed of propagation of electromagnetic radiation) in a vacuum, denoted c, is an important fundamental physical constant in many areas of physics. It has an exact value of 299,792,458 meters per second, because the meter length unit is redefined based on this constant and the standard second. According to special relativity, c is the maximum speed that all energy, matter, and information in the universe can reach. It is the speed at which every massless particle bound to physical fields (including electromagnetic radiation such as light photons) propagates in a vacuum. It is also the propagation speed of gravity (such as gravitational waves) predicted by current theories. Particles and waves travel with velocity c regardless of the motion of the source or of the observer’s inertial frame of reference. After Einstein founded relativity, it became known that the speed of light is indeed very fast, because this is the upper limit of the local speed in the universe, and no other speed can be exceeded. through it. Moreover, regardless of the medium in the frame of reference, the measured speed of light is exactly the same. Based on the principle of the constant speed of light in relativity and the highly accurate measurement of the speed of light, physicists have also determined the speed of light to be 299,792,458 meters/second without affecting the speed of light. affect the current physical quantity. In this way, people no longer have to worry about accurately measuring the speed of light, and can also solve the problem of errors in the equipment used to determine the clock. The speed of light propagating in a vacuum is independent of both the motion of the light source as well as of the observer’s inertial frame of reference. The constancy of the speed of light was postulated by Einstein in his 1905 paper on special relativity. Physicists can now only experimentally confirm the speed of light by methods above two Two-way speed of light is frame-independent, because the speed of light cannot be measured in one-way speed of light, ignoring some conventions of uniformity. synchronization between the clock at the source and the clock at the receiver. Whether it’s electron transition, nuclear fusion, nuclear fission, or the annihilation of yin and yang matter, these processes produce light. Once light is created, their speed will immediately reach the speed of light, and they will always travel at this speed. If light were not absorbed by matter, they would not be dissipated in the universe, and the speed would always remain at the speed of light. For example, the first photons created in the universe 13.8 billion years ago are still present today, and they travel through the universe at the speed of light. So, how did light reach the speed of light? How does light maintain the speed of light? What is the driving force that drives the light forward? If it is explained from the point of view of the particle nature of light, then light is composed of photons with no rest mass. According to special relativity, since the static mass of photons is zero, their speed can only be the speed of light. According to the Higgs mechanism of the Standard Model of Particle Physics, when photons without static mass pass through the Higgs field throughout the universe, the photons will not be coupled, so they will not gain static mass, and their speed will not decrease. Once the photons are generated, their speed will directly reach the speed of light, and there is no acceleration from zero to the speed of light. Propagation of photons does not require energy to propagate, if they were not absorbed by matter or a black hole, they would always travel aimlessly through a vacuum at the speed of light. On the other hand, if explained from the evaporation of light, the nature of light is electromagnetic wave. Maxwell’s equations of electromagnetism show that electricity and magnetic fields are essentially unified, that a changing electric field excites a magnetic field, and a changing magnetic field excites a repeated electric field, creating out electromagnetic waves. Since electromagnetic fields are formed at the speed of light, electromagnetic waves travel at the speed of light. The generation and existence of electromagnetic fields are independent of the medium, so light can travel at the speed of light in a vacuum. Although the spatial structure continues to expand, light propagating through space will appear redshift, but they will not completely disappear in the universe.

During a trip to discover the village of Bru Van Kieu people in Quang Binh, blogger Vinh Bear took time to visit Cha Loi cave. Before the trip, the tour unit will give visitors helmets with lights, army shoes for trekking and gloves for climbing… The structure of Cha Loi cave is divided into 3 floors. The 2nd floor is the entrance to the cave, after that, visitors will move down to the 1st floor and finish by climbing up to the exit on the 3rd floor. “As soon as I got to the cave entrance, I saw the cool breeze inside blowing out. Turning on the flashlight to shine inside, I started the journey to discover Cha Loi”, Vinh Bear shared. The first impression is the stalactites in the cave. This blogger admitted to having “A eyes, O mouth” when looking at the natural masterpieces of Cha Loi cave. It is known that each year, stalactites are only about 0.03 mm long. Therefore, visitors absolutely do not touch or touch them during the exploration of the cave. Leaving the 2nd floor, you will go down to the 1st floor to continue the journey of discovery. The stalactites on this floor are equally majestic as the ones above. However, it is more special because there are stalactites like human heads. A stalactite block shaped like a bust of General Vo Nguyen Giap. In addition, Cha Loi cave is also known as “Ong Giap cave”. A better view of the famous stalactite in the cave. In the journey to explore the cave, you also need to be prepared to wade in the water. Some sections of water are just knee-high. However, there is a stretch of water up to the chest. Impressive pictures when checking-in in the cave is what you can expect with this exploration. The journey to explore Cha Loi cave takes about 4 hours. According to Vinh Bear, this is a relatively suitable journey for all subjects. “In my group there is a 60-year-old girl and two 6-year-old children, but walking is not difficult,” he said. After the adventure in the cave, the group moved to Ban Coi. There is a love valley area suitable for night camping. There are only 3 Bru Van Kieu households living in this area. After setting up the tent, you can immerse yourself in the cool stream to wash away dirt in the process of exploring Cha Loi cave. “The feeling is nothing. Alone, free to struggle”, Vinh Bear shared. The dishes will be prepared by Bru Van Kieu people. This time, the group enjoyed roast pork, walking chicken and fresh river fish. “One of the things I like most here is that people talk to each other more. This area has no phone signal, so messages and social media notifications can’t distract us,” he said.

Advantages of yachts Professional staff attitude My first impression was the warm welcome from the staff. To get to the cruise, guests have to take a speedboat to the middle of the bay. When the ship approaches the yacht, staff such as chefs, receptionists, bartenders… all stand out and wave to welcome guests. This is a professional gesture, easy to win sympathy. During the time on board, the staff also support customers enthusiastically and pay attention to the smallest details. The behavior and attitude of the staff is the plus point of the journey. Beautiful design In fact, the 5-star yachts on Lan Ha or Ha Long Bay now have a luxurious design, different from the old-fashioned bay cruise ships. Walking 3 floors of the yacht, you will find enough angles to take pictures of “fire”. Guests can also go to the deck to check-in the pool or pose with the beautiful bay in the background. Luxury yacht space, many beautiful photo angles. For those who prefer a little more “sexy” photography, the bathroom is definitely worth a try. The bathtub is located right next to a bay view window. Just a little alignment, a sexy photo with the natural space behind is not difficult. Beautiful and delicious “fine dining” meal At dinner, guests will experience fine dining with dishes such as oysters, abalone soup, grilled shrimp… In my opinion, seafood is fresh and delicious. The processing method is not too traditional, suitable for modern people. Delicious, beautiful dinner, suitable for those who like to take pictures of food. The plus point of the meal is the beautiful decoration. Tourists who have the habit of showing off their photos before a meal will surely like “both eyes and stomach” when the dishes are presented. Diverse experiences During 2 days and 1 night on the cruise, you can choose to join a cooking class, practice vovinam or kayak, explore caves… In general, with a leisurely schedule, this is enough for you and your loved ones to experience. However, for families with young children, these activities are not very suitable. Unsatisfied things Weak phone signal If you are looking for a place completely separate from daily life, a yacht is definitely a great choice. However, for those who still need to update news and work, this is an unnecessary experience. Weak waves are what makes many travelers uncomfortable while on cruises. Of course, the weak phone signal is not the yacht’s fault. This is something you have to learn to accept as you go deeper into the bay. However, this also makes the experience of many customers less pleasant. Not vibrant You can see the luxury yachts bobbing in the music on the film. However, this is not something you can see when traveling on cruises in Vietnam. Most tourists go on a cruise to relax. In addition, despite the discount compared to before the epidemic, the fee for 2 days and 1 night on the cruise is still relatively high (about 2.7 million VND/adult). Therefore, most of the guests on the yacht are families, honeymooning couples, relaxing… Quite a few groups of young people choose yachts. Life on a yacht is not as exciting as it is in the movies. Therefore, before deciding to choose this form of tourism, you should put aside the vibrant images often seen on movies. Life on the yacht passed quite gently and smoothly. Even the bar on the deck is not very lively at night. At about 0:00, the music was turned off to avoid disturbing other guests. Buffet is not diverse The “fine dining” meal is a plus for the cuisine on the cruise, but the buffet is not worthy of the “5 star” title. Quite a few options for the lunch and breakfast buffet. The food is not too special, repeating dishes such as corn soup, fried noodles, fried squid… You should choose a 5-star yacht if you belong to the following groups: – Family on vacation – Couple on vacation/honeymoon… – People who like to check-in luxurious and sexy space – No seasickness (in fact, the cruise is relatively quiet) – No work pressure related to phone, laptop…

Album Into The Woods Mr. Dang Cong Nhat (HCMC) recorded a 2-day and 1-night picnic in Lac Duong forest, pursuing a type of Vintage camping (traditional camping). “We chose Lac Duong because this location is not too difficult to go, moreover, the terrain and climate suitable for the vintage fashion we pursue”, Mr. Cong Nhat shared with Zing. “Unlike normal travel, nature discovery journey offers a more enjoyable experience,” he said. The trip has a style similar to wildlife survival but is not challenging but aims to be in harmony with nature and explore your own limits. The necessary equipment for the trip include: cooking utensils, tents, sleeping bags, blankets, waterproof tarpaulins, and some camping tools such as knives, axes, lights … “The items are synchronous, the same style is Vintage Americana (American classic), but each member will have variations. Like me the Vintage Military style (military classic) with US WW2 tent (American tent However, most of the items dating back to the 1930s – 1970s, have the same design and materials to create a unified whole, “Nhat said. Vintage Camping has many limitations because it does not have the support of modern equipment, needs proficiency skills, as well as physical requirements. However, the trip offers an unforgettable experience. Spent two days without phone waves, no noise or dust pollution, Nhat said: “Camping like this helps to feel more with nature. We can watch more and more carefully because we often camp. Two days or more. Fun activities like spring bath, cooking, night star viewing, or regional botanical exploration. This type of picnic is quite new in Vietnam. “If young people want to join, we should camp in close and safe places first to gain experience. We also go for many years before we dare to go,” said Nhat. He added: “Vintage Camping is for those who are really passionate because they have to spend time researching and understanding each item, the amount of money to own them is not cheap.”

Reputation of the hero From the pier in Tam Thon Hiep commune, Can Gio district, we followed a canoe to the headquarters of Division 1 – a forest protection unit belonging to the Can Gio Mangrove Management Board (MB). In the midst of the immense water waves, talent Nguyen Hoang Phi, an employee of Can Gio Mangrove Management Board, skillfully allowed a canoe to turn the waves of Long Tau River towards the Dua River, soaring. The wind winds all four sides, taking a full breath, it feels like all the freshness, freshness of the sea, the green forest is going deep into the chest. Belonging to the next generation, he has never held a gun to fight in fierce war days, but when it comes to Rung Sac, Phi can never stop talking. Just right on the Long Tau river, he proudly: “This is a” graveyard “buried hundreds of enemy warships, including many military transport ships with a tonnage of tens of thousands of tons. Come is the river that contributes to the honor of the heroic Rung Sac “. The Standing Deputy Secretary of Ho Chi Minh City Party Committee Tran Luu Quang planted a souvenir tree at Rung Sac Square on April 27, on the occasion of the People’s Committee of the city announcing the Prime Minister’s decision to recognize Can Gio district meeting the new rural standard. 2020 Photo: HOANG Trieu In order to decipher this strategic position, in order to block the enemy’s military supply path, protect our supply forces, on April 15, 1966, the Regional Command decided to establish the Special Forest Military Zone. Sac (later renamed to Group 10 Special Forces of Rung Sac). Since then, Rung Sac is within the range of enemy destruction. Can Gio Mangrove Management Board is managing and protecting 34,713.64 ha of forest and forestry land, of which forest area accounts for 32,446.44 ha; allotted forest protection to 133 households and 11 units. Anh Phi said that in the early years of the resistance war against the US, the forest was dense with trees. But from 1964 onwards, more than 4 million liters of chemicals, 2 million tons of bombs and ammunition of the enemy fell down to devastate, making Rung Sac almost bare. The special mission combatants Rung Sac fell into poverty in the middle of the wild. However, thanks to the “natural la geotung” map with a series of canals, forest trees form favorable walls for guerrilla tactics, shielding our troops from the eyes of the enemy, along with our products. Heaven bestowed and the warfare inherent in the people, Rung Sac base was still not wavering. Residents of the forest After half an hour of floating, the canoe took us to Division 1 headquarters. It was a grade 4 house built on a triangular islet in Tam Thôn Hiệp commune overlooking the Dua River, surrounded by marshland. drown. This is the workplace and living place of 4 officers, employees, managers of 14 households and 28 employees of the subdivision. Mr. Tran Van Ho, Head of Division 1, picked us up and took us around the headquarters. What caught our eyes was the simple leaf kitchen, full of black pots and pans. Mr. Ho pointed to a wood stove hidden in the corner, and said that in the first wave, this wind was very rare. To save money, people only use firewood for cooking. In Can Gio forest, green vegetables are also precious because the soil here is almost completely acidic. If you want to grow vegetables, you need to invest in soil, manure and fresh water from the shore. However, the most precious is still fresh water. Only the rainwater tanks located around the Division 1 headquarters, Mr. Ho explained: “The water here is 120,000 VND / block, but sometimes there are boats changing. Therefore, the subdivision is equipped with these tanks to catch the water. rain water used. Many households around, when the water runs out, often stop by and ask, whoever wants to scoop as much as possible “. Telephone waves in Rung Sac are “luxury”. Where the waves can be caught, the forest guard leaves the phone “catchy” like this. Photo: TUYET TRINH Seeing that on a number of pillars in the kitchen where there are many horizontal plastic bottles, we asked curiously, Mr. Ho replied: “This is the phone holder to … catch the signal”. It turns out, not only lack of necessities, but also the telephone signal here is a “luxury”. Where you can catch the phone signal, you tie up bottles like this to mark it. Lack of and many things, Mr. Ho has been sticking to the forest for more than 20 years. “So attached, now I no longer think about going ashore looking for another job. Getting acquainted with the muddy smell, the taste of salty water here and I can not leave,” – he said, his eyes dazed. up steadiness, steadfastness. Mr. Ho took us to visit the people of the second generation who are continuing their parents to protect and preserve Sac Forest. The first place we visited was the family of Mr. Nguyen Hoang Phien – brother of Phi, the leader of Division 1 Self-Management Group. Session said that his father, Mr. Nguyen Van No, was one of the 10 first forest keepers in Rung Sac. In 2012, Phien succeeded his father, “partly due to a difficult family and unable to go to school; a part has attached blood and flesh to each tree, the wave of when my brothers were in a hurry to practice speaking” . The session emphasized that the most important job of contracted households here is forest patrol. Mr. Phien’s family is managing 109 hectares, on average, each month, he patrols 20-30 times regardless of day and night, including traveling alone and with self-management team. Patrols must be done regularly to promptly detect if forest loggers or wildlife have appeared. Leaving Mr. Phien’s house, we went to the forest post of Mr. Tran Minh Tung’s family. Canoes run in the middle of the immense Sac Forest, Mr. Ho shows us how to distinguish fish, mangrove, tiger, parrot … covered like “roofs”. In more than 32,447 hectares of forest today, there are over 60 species of plants, each having its own role in the “war” with the sea. He said: “In it, mangroves play the role of reinforcing the battlefield, because with the intricate roots, the tall and wide foliage, it can retain what is most necessary that water has brought to the earth”. Launching our eyes around, we were very pleased with the blue landscape. It is hard to imagine this is a land that once suffered from enemy bombs and chemical toxins decades ago. The green color of the forest has covered all traces of the war, making it difficult for visitors to imagine this is a land once destroyed by bombs. Talking about the revival of this dead land, it must be mentioned the efforts of tens of thousands of people from all over the districts of Saigon – Ho Chi Minh City, the core of the youth volunteer force has poured in here to plant trees and rejuvenate. forest creation. Among those people was Mrs. Dinh Thi Hong, the mother of Mr. Tran Minh Tung. Like the Phi – Phien brothers, Tung also had a childhood associated with Rung Sac – Can Gio. When he was a child, he went with his mother to plant forests. Growing up, thanks to planting forests, he met his wife today. Later, he and his wife stayed in Can Gio, replacing their mother to keep the forest. In the afternoon, the canoe took us back to the pier. The sudden beating in the deep water made us startled because we remembered the stories about the water in the past where many crocodiles were hiding and stalking this person. In the forest there are many dangers, poor living conditions. However, the residents that we have met or known through the story have never intended to leave the forest to live on shore. Many people stick to their parents’ career, others – like Tung and his wife – are unable to leave a peaceful life thanks to being surrounded by mother nature here. “We stick wherever we go, we can do everything together. That is happy enough” – Mr. Tung expressed. In the distance, looking at the identical mangrove forests that have opened up the direction of ecotourism development for Can Gio, we again silently thank the residents of Rung Sac who have been sticking to this day. The most fear is deforestation At night, driving a motorboat to patrol and guard the forest, there are all kinds of dangers waiting for unarmed people like Nguyen Hoang Phien if they accidentally face a logger or a wild beast. We asked Phien if he was afraid, he laughed: “The most fearful thing is the loss of the forest”. “In the past, following my father to the forest, I have many times encountered loggers and” lash out “on the river. Later, due to good propaganda and awareness raising for the people, there is no longer a phenomenon. cutting trees, deforestation “- Mr. Phien said.

Doctor Nguyen Van Cong – Deputy Director of Cardiology Center, Vinh Phuc General Hospital said: As for the syndrome of Nguyen Thanh A patient encountered, it is a rare disease, especially young patients. The treatment is somewhat more difficult, in addition to the time of treatment (fast, timely) also has a great significance in keeping the patient’s life. Currently, there are 3 methods of treating disease such as using electric shock machines, drugs to suppress the disease and electromagnetic waves to detect the location to burn (damage) and destroy the disease waves. The above methods are the most radical treatment plan compared to other methods, definitive treatment does not recur.

Doctor Nguyen Van Cong added that the case of A patient was the first case of Wolff Parkinson White syndrome successfully treated by Vinh Phuc General Hospital. Usually, this dangerous disease will have to be transferred to higher levels for treatment and few provincial hospitals can treat patients with the above syndrome.

Before that, patient Nguyen Thanh Y was taken to Vinh Phuc Province General Hospital on April 11, 2021 with clinical symptoms such as anxiety, shortness of breath, chest pain, and heart palpitations. Admitting the patient, the doctors diagnosed the patient with paroxysmal tachycardia, the time of checking the patient’s heart rate 229 times / minute (compared with a normal person with a heart rate of 70-80 times / minute). Patient was diagnosed with Wolff Parkinson White syndrome (WPW), described in 1930 by 3 authors L. Wolff; J. Parkison and PD White. The development of the patient’s health, the treating doctors contacted Hanoi Heart Hospital for professional and technical support. Through confirmed diagnosis this is a case of Wolff Parkinson White syndrome, very rare, the rate of 20 to 30 people / hundred thousand people. With a scientific treatment regimen, after 1.5 hours of actively treating Nguyen Thanh Ut patient’s health, she has recovered normally. Currently, the patient’s health is stable.