Time travel is the hypothetical activity of traveling into the past or future. Time travel is a concept in philosophy and fiction, particularly science fiction. In fiction, time travel is typically achieved through the use of a device known as a time machine. The idea of a time machine was popularized by H. G. Wells's 1895 novel The Time Machine.
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.
John Titor and TimeTravel_0 are pseudonyms used in communications and on internet forums between 1998 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.
The Hartle–Hawking state, also known as the no-boundary wave function is a proposal in theoretical physics concerning the state of the universe prior to the Planck epoch. It is named after James Hartle and Stephen Hawking.
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 online. 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.
Model-dependent realism is a view of scientific inquiry that focuses on the role of scientific models of phenomena. It claims reality should be interpreted based upon these models, and where several models overlap in describing a particular subject, multiple, equally valid, realities exist. It claims that it is meaningless to talk about the "true reality" of a model as we can never be absolutely certain of anything. The only meaningful thing is the usefulness of the model. The term "model-dependent realism" was coined by Stephen Hawking and Leonard Mlodinow in their 2010 book, The Grand Design.
Visitors to Azerbaijan must obtain a visa from one of the Azerbaijani diplomatic missions unless they are citizens of one of the visa-exempt countries, or citizens eligible for an electronic visa on arrival, or citizens eligible for an electronic visa.
Harsh Vardhan is a former Indian politician and 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 the executive board of the World Health Organization from 22 May 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 before divorcing.
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.
Peter Dean is a British artist and designer. His artistic work often takes inspiration from examples of Victorian letterpress printing. He is most notable for his recreation of the Victorian circus poster that was owned by John Lennon and inspired the Beatles song Being for the Benefit of Mr. Kite!. as well as creating the poster at the centre of Stephen Hawking’s famous time travel experiment. His work can be found in both the permanent collections of the Victoria and Albert Museum and the Science Museum, both in London, UK and has also been seen on The Late Show with Stephen Colbert.
