A black hole is a region of spacetime where gravity is so strong that nothing, not even light and other electromagnetic waves, is 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. 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.
Jet lag, or desynchronosis, is a temporary physiological condition that occurs when a person's circadian rhythm is out of sync with the time zone they are in, and is a typical result from travelling rapidly across multiple time zones. For example, someone travelling from New York to London, i.e. from west to east, feels as if the time were five hours earlier than local time, and someone travelling from London to New York, i.e. from east to west, feels as if the time were five hours later than local time. The phase shift when travelling from east to west is referred to as phase-delay of the circadian cycle, whereas going west to east is phase-advance of the cycle. Most travellers find that it is harder to adjust time zones when travelling east. Jet lag was previously classified as a circadian rhythm sleep disorder.
Hawking radiation is the theoretical thermal black-body radiation released outside a black hole's event horizon. This is counterintuitive because once ordinary electromagnetic radiation is inside the event horizon, it cannot escape. It is named after the physicist Stephen Hawking, who developed a theoretical argument for its existence in 1974. Hawking radiation is predicted to be extremely faint and is many orders of magnitude below the current best telescopes' detecting ability.
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.
In physics, black hole thermodynamics is the area of study that seeks to reconcile the laws of thermodynamics with the existence of black hole event horizons. As the study of the statistical mechanics of black-body radiation led to the development of the theory of quantum mechanics, the effort to understand the statistical mechanics of black holes has had a deep impact upon the understanding of quantum gravity, leading to the formulation of the holographic principle.
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 and is the second oldest continuously running debating society in the world, behind the University of St Andrews Union Debating Society. 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. His 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.
A travel agency is a private retailer or public service that provides travel and tourism-related services to the general public on behalf of accommodation or travel suppliers to offer different kinds of travelling packages for each destination. Travel agencies can provide outdoor recreation, arranging logistics for luggage and medical items delivery for travellers upon request, public transport timetables, car rentals, and bureau de change services. Travel agencies can also serve as general sales agents for airlines that do not have offices in a specific region. A travel agency's main function is to act as an agent, selling travel products and services on behalf of a supplier. They are also called Travel Advisors. They do not keep inventory in-hand unless they have pre-booked hotel rooms or cabins on a cruise ship for a group travel event such as a wedding, honeymoon, or other group event.
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.
Jane Beryl Wilde Hawking Jones is an English author and teacher. She was married to Stephen Hawking for 30 years before divorcing.
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.
