A black hole is a region of spacetime where gravity is so strong that nothing, including light and other electromagnetic waves, are capable of possessing enough energy to escape it. Einstein's theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of no escape is called the event horizon. A black hole has a great effect on the fate and circumstances of an object crossing it, but it has no locally detectable features according to general relativity. In many ways, a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is of the order of billionths of a kelvin for stellar black holes, making it essentially impossible to observe directly.
Time travel is the hypothetical activity of traveling into the past or future. Time travel is a widely recognized concept in philosophy and fiction, particularly science fiction. In fiction, time travel is typically achieved through the use of a hypothetical device known as a time machine. The idea of a time machine was popularized by H. G. Wells's 1895 novel The Time Machine.
Smithsonian is a science and nature magazine, and is the official journal published by the Smithsonian Institution in Washington, D.C., although editorially independent from its parent organization. The first issue was published in 1970. The Smithsonian holds events such as the American Ingenuity Awards, Future Con, and Museum Day.
In general relativity, a white hole is a hypothetical region of spacetime and singularity that cannot be entered from the outside, although energy-matter, light and information can escape from it. In this sense, it is the reverse of a black hole, from which energy-matter, light and information cannot escape. White holes appear in the theory of eternal black holes. In addition to a black hole region in the future, such a solution of the Einstein field equations has a white hole region in its past. This region does not exist for black holes that have formed through gravitational collapse, however, nor are there any observed physical processes through which a white hole could be formed.
The Cambridge Union Society, also known as the Cambridge Union, is a debating and free speech society in Cambridge, England, and the largest society in the University of Cambridge. The society was founded in 1815, it is the oldest continuously running debating society in the world. Additionally, the Cambridge Union has served as a model for the foundation of similar societies at several other prominent universities, including the Oxford Union and the Yale Political Union. The Union is a private society with membership open to all students of Cambridge University and Anglia Ruskin University. The Cambridge Union is a registered charity and is completely separate from the Cambridge University Students' Union.
John Titor and TimeTravel_0 are pseudonyms used on internet forums between 2000 and 2001 by an individual claiming to be an American military time traveler from the year 2036. Their posts discussed various aspects of time travel, and described future calamitous events, including a global nuclear war. The uniform inaccuracy of their predictions and inconsistencies in their explanations has led many to view the story with skepticism. A 2009 investigation suggested that the entire affair was a hoax created by Larry Haber, a Florida entertainment lawyer, and his brother John Rick Haber, a computer scientist. These claims have never been verified.
The chronology protection conjecture is a hypothesis first proposed by Stephen Hawking that laws of physics beyond those of standard general relativity prevent time travel on all but microscopic scales - even when the latter theory states that it should be possible. The permissibility of time travel is represented mathematically by the existence of closed timelike curves in some solutions to the field equations of general relativity. The chronology protection conjecture should be distinguished from chronological censorship under which every closed timelike curve passes through an event horizon, which might prevent an observer from detecting the causal violation.
A temporal paradox, time paradox, or time travel paradox, is a paradox, an apparent contradiction, or logical contradiction associated with the idea of time travel or other foreknowledge of the future. While the notion of time travel to the future complies with the current understanding of physics via relativistic time dilation, temporal paradoxes arise from circumstances involving hypothetical time travel to the past – and are often used to demonstrate its impossibility.
A bachelorette party or hen night is a party held for a woman who will soon be married. While Beth Montemurro concludes that the bachelorette party is modelled after the centuries-old stag night in the US, which is itself historically a dinner given by the bridegroom to his friends shortly before his wedding, Sheila Young argues that its British counterpart evolved from a number of earlier pre-wedding traditions for women whose origins are obscure but which have been around for at least a century in factories and offices across the UK. Despite its reputation as "a sodden farewell to maiden days" or "an evening of debauchery", these events can simply be parties given in honor of the bride-to-be, in the style that is common to that social circle.
Ronald Lawrence Mallett is an American theoretical physicist, academic and author. He has been a faculty member of the University of Connecticut since 1975 and is best known for his position on the possibility of time travel.
Time travel is a common theme in fiction, mainly since the late 19th century, and has been depicted in a variety of media, such as literature, television, film, and advertisements.
Stephen Hawking (1942–2018), a theoretical physicist, has appeared in many works of popular culture.
Stephen William Hawking was an English theoretical physicist, cosmologist, and author who was director of research at the Centre for Theoretical Cosmology at the University of Cambridge. Between 1979 and 2009, he was the Lucasian Professor of Mathematics at Cambridge, widely viewed as one of the most prestigious academic posts in the world.
There have been multiple accounts of people who allegedly travelled through time reported by the press or circulated on the internet. These reports have turned out either to be hoaxes or to be based on incorrect assumptions, incomplete information, or interpretation of fiction as fact, many being now recognized as urban legends.
Workaway is a platform that allows members to arrange homestays and cultural exchange. Volunteers or "Workawayers", are expected to contribute a pre-agreed amount of time per day in exchange for lodging and food, which is provided by their host.
Harsh Vardhan is an Indian otorhinolaryngologist. He had served as the Minister of Health and Family Welfare, Minister of Science and Technology and Minister of Earth Sciences in the BJP-led NDA government of Prime Minister Narendra Modi from 30 May 2019 to 7 July 2021. He represents Chandni Chowk in Delhi as a Member of Parliament in the 17th Lok Sabha. He was elected to the office of chairperson of executive board of the World Health Organization from May 22, 2020. Vardhan has been prominent in the Indian government's response to the COVID-19 pandemic. He later resigned from his cabinet post ahead of the cabinet reshuffle in July 2021.
Jane Beryl Wilde Hawking Jones is an English author and teacher. She was married to Stephen Hawking for 30 years.
Breakthrough Starshot is a research and engineering project by the Breakthrough Initiatives to develop a proof-of-concept fleet of light sail interstellar probes named Starchip, to be capable of making the journey to the Alpha Centauri star system 4.34 light-years away. It was founded in 2016 by Yuri Milner, Stephen Hawking, and Mark Zuckerberg.
Brief Answers to the Big Questions is a popular science book written by physicist Stephen Hawking, and published by Hodder & Stoughton (hardcover) and Bantam Books (paperback) on 16 October 2018. The book examines some of the universe's greatest mysteries, and promotes the view that science is very important in helping to solve problems on planet Earth. The publisher describes the book as "a selection of [Hawking's] most profound, accessible, and timely reflections from his personal archive", and is based on, according to a book reviewer, "half a million or so words" from his essays, lectures and keynote speeches.
The following is a timeline of the COVID-19 pandemic in Singapore in 2021.
