The Aharonov–Bohm effect, sometimes called the Ehrenberg–Siday–Aharonov–Bohm effect, is a quantum-mechanical phenomenon in which an electrically charged particle is affected by an electromagnetic potential ( φ {\\displaystyle \\varphi } , A {\\displaystyle \\mathbf {A} } ), despite being confined to a region in which both the magnetic field B {\\displaystyle \\mathbf {B} } and electric field E {\\displaystyle \\mathbf {E} }
The ant on a rubber rope is a mathematical puzzle with a solution that appears counterintuitive or paradoxical. It is sometimes given as a worm, or inchworm, on a rubber or elastic band, but the principles of the puzzle remain the same.
A supertask is a countably infinite sequence of operations that occur sequentially within a finite interval of time. Supertasks are called hypertasks when the number of operations is uncountable.
The black hole information paradox is an unsolved problem in physics and a paradox that appears when the predictions of quantum mechanics and general relativity are combined. The theory of general relativity predicts the existence of black holes that are regions of spacetime from which nothing—not even light—can escape.
A temporal paradox, time paradox, or time travel paradox, is an apparent or actual contradiction associated with the idea of time travel or other foreknowledge of the future. Temporal paradoxes arise from circumstances involving hypothetical time travel to the past.
In probability theory, the Borel–Kolmogorov paradox (sometimes known as Borel's paradox) is a paradox relating to conditional probability with respect to an event of probability zero (also known as a null set). It is named after Émile Borel and Andrey Kolmogorov.
A temporal paradox, time paradox, or time travel paradox, is an apparent or actual contradiction associated with the idea of time travel or other foreknowledge of the future. Temporal paradoxes arise from circumstances involving hypothetical time travel to the past.
Charlesworth's Paradox is a paradox related to kin selection, Hamilton's Rule and the evolution of altruism. The paradox was proposed by Brian Charlesworth and is sometimes used as a teaching example to discuss kin selection.
In decision theory, economics, and probability theory, the Dutch book arguments are a set of results showing that agents must satisfy the axioms of rational choice to avoid a kind of self-contradiction called a Dutch book. A Dutch book, sometimes also called a money pump, is a set of bets that ensures a guaranteed loss, i.e., the gambler will lose money no matter what happens.
In mathematics, a set is countable if either it is finite or it can be made in one to one correspondence with the set of natural numbers. Equivalently, a set is countable if there exists an injective function from it into the natural numbers; this means that each element in the set may be associated to a unique natural number, or that the elements of the set can be counted one at a time, although the counting may nev
Fredkin's paradox reads 'The more equally attractive two alternatives seem, the harder it can be to choose between them—no matter that, to the same degree, the choice can only matter less.' Thus, a decision-making agent might spend the most time on the least important decisions. It was proposed by American physicist Edward Fredkin.
The new riddle of induction was presented by Nelson Goodman in Fact, Fiction, and Forecast as a successor to Hume's original problem. It presents the logical predicates grue and bleen which are unusual due to their time-dependence.
A temporal paradox, time paradox, or time travel paradox, is an apparent or actual contradiction associated with the idea of time travel or other foreknowledge of the future. Temporal paradoxes arise from circumstances involving hypothetical time travel to the past.
The Green Paradox is a controversial book by German economist, Hans-Werner Sinn, describing the observation that an environmental policy that becomes greener with the passage of time acts like an announced expropriation for the owners of fossil fuel resources, inducing them to accelerate resource extraction and hence to accelerate global warming.
The Grelling–Nelson paradox arises from the question of whether the term 'non-self-descriptive' is self-descriptive. It was formulated in 1908 by Kurt Grelling and Leonard Nelson, and is sometimes mistakenly attributed to the German philosopher and mathematician Hermann Weyl thus occasionally called Weyl's paradox or Grelling's paradox.
In philosophy, the Grim Reaper paradox is a paradox involving an infinite sequence of Grim Reapers, each tasked with killing a person if no reaper has already killed them. The paradox raises questions about the possibility of continuous time and the infinite past (temporal finitism).
The hedgehog's dilemma, or sometimes the porcupine dilemma, is a metaphor about the challenges of human intimacy. It describes a situation in which a group of hedgehogs seek to move close to one another to share heat during cold weather.
A temporal paradox, time paradox, or time travel paradox, is an apparent or actual contradiction associated with the idea of time travel or other foreknowledge of the future. Temporal paradoxes arise from circumstances involving hypothetical time travel to the past.
I know that I know nothing' is a saying derived from Plato's account of the Greek philosopher Socrates: 'For I was conscious that I knew practically nothing...' (Plato, Apology 22d, translated by Harold North Fowler, 1966). It is also sometimes called the Socratic paradox, although this name is often instead used to refer to other seemingly paradoxical claims made by Socrates in Plato's dialogues (most notably, Socr
In metaphysics, identity (from Latin: identitas, 'sameness') is the relation each thing bears only to itself. The notion of identity gives rise to many philosophical problems, including the identity of indiscernibles (if x and y share all their properties, are they one and the same thing?), and questions about change and personal identity over time (what has to be the case for a person x at one time and a person y at
The infinite monkey theorem states that a monkey hitting keys independently and at random on a typewriter keyboard for an infinite amount of time will almost surely type any given text, including the complete works of William Shakespeare. More precisely, under the assumption of independence and randomness of each keystroke, the monkey would almost surely type every possible finite text an infinite number of times.
Renewal theory is the branch of probability theory that generalizes the Poisson process for arbitrary holding times. Instead of exponentially distributed holding times, a renewal process may have any independent and identically distributed (IID) holding times that have finite expectation.
In the social sciences, unintended consequences (sometimes unanticipated consequences or unforeseen consequences, more colloquially called knock-on effects) are outcomes of a purposeful action that are not intended or foreseen. The term was popularized in the 20th century by American sociologist Robert K. Merton.
Lombard's paradox describes a paradoxical muscular contraction in humans. When rising to stand from a sitting or squatting position, both the hamstrings and quadriceps contract at the same time, despite them being antagonists to each other.
In physics, Loschmidt's paradox (named for Josef Loschmidt), also known as the reversibility paradox, irreversibility paradox, or Umkehreinwand (from German 'reversal objection'), is the objection that it should not be possible to deduce an irreversible process from time-symmetric dynamics. This puts the time reversal symmetry of (almost) all known low-level fundamental physical processes at odds with any attempt to
In logic and probability theory, two events (or propositions) are mutually exclusive or disjoint if they cannot both occur at the same time. A clear example is the set of outcomes of a single coin toss, which can result in either heads or tails, but not both.
The new riddle of induction was presented by Nelson Goodman in Fact, Fiction, and Forecast as a successor to Hume's original problem. It presents the logical predicates grue and bleen which are unusual due to their time-dependence.
In philosophy, the original position is a hypothetical position from which members of society would consider which principles they would select for the basic structure of their society if they had no knowledge ahead of time regarding the position which they would end up occupying in that society. The idea of having no such knowledge, because everyone is behind a veil of ignorance, represents a thought experiment ofte
The sorites paradox (), sometimes known as the paradox of the heap, is a paradox that results from vague predicates. A typical formulation involves a heap of sand, from which grains are removed individually.
Peto's paradox is the observation that, at the species level, the incidence of cancer does not appear to correlate with the number of cells in an organism. For example, the incidence of cancer in humans is much higher than the incidence of cancer in whales, despite a whale having about 1000 times more cells than a human.
In quantum mechanics, frequent measurements cause the quantum Zeno effect, a reduction in transitions away from the system's initial state, slowing a system's time evolution. Sometimes this effect is interpreted as 'a system cannot change while you are watching it'.
The region-beta paradox is the phenomenon that people can sometimes recover more quickly from more distressing experiences than from less distressing ones. The hypothesized reason is that intense states trigger psychological defense processes that reduce the distress, while less intense states do not trigger the same psychological defense processes and, therefore, less effective attenuation of the stress occurs.
Science fiction (often shortened to sci-fi or abbreviated SF) is the genre of speculative, science-based fiction that imagines advanced and futuristic scientific or technological progress. The elements of science fiction have evolved over time: from space exploration, extraterrestrial life, time travel, and robotics; to parallel universes, dystopian societies, and biological manipulations; and, most lately, to inform
The Ship of Theseus, also known as Theseus's Paradox, is a paradox and common thought experiment about whether an object (in the most common stating of the paradox, a ship) is the same object after having all of its original components replaced with others over time. In Greek mythology, Theseus, the mythical king of the city of Athens, rescued the children of Athens from King Minos after slaying the Minotaur and then
The Sleeping Beauty problem, also known as the Sleeping Beauty paradox, is a puzzle in decision theory in which an ideally rational epistemic agent is told she will be awoken from sleep either once or twice according to the toss of a coin. Each time she will have no memory of whether she has been awoken before, and is asked what her degree of belief that 'the outcome of the coin toss is Heads' ought to be when she is
The Sleeping Beauty problem, also known as the Sleeping Beauty paradox, is a puzzle in decision theory in which an ideally rational epistemic agent is told she will be awoken from sleep either once or twice according to the toss of a coin. Each time she will have no memory of whether she has been awoken before, and is asked what her degree of belief that 'the outcome of the coin toss is Heads' ought to be when she is
The sorites paradox (), sometimes known as the paradox of the heap, is a paradox that results from vague predicates. A typical formulation involves a heap of sand, from which grains are removed individually.
A supertask is a countably infinite sequence of operations that occur sequentially within a finite interval of time. Supertasks are called hypertasks when the number of operations is uncountable.
In fluid dynamics, the tea leaf paradox is a phenomenon where tea leaves in a cup of tea migrate to the center and bottom of the cup after being stirred rather than being forced to the edges of the cup, as would be expected in a spiral centrifuge. The correct physical explanation of the paradox was for the first time given by James Thomson in 1857.
A temporal paradox, time paradox, or time travel paradox, is an apparent or actual contradiction associated with the idea of time travel or other foreknowledge of the future. Temporal paradoxes arise from circumstances involving hypothetical time travel to the past.
The beer question is a thought experiment in politics that attempts to measure authenticity and likability in politicians by asking or polling voters about which politicians they would prefer to drink beer with, as in, spending casual time 'hanging out' with. The question has been discussed as far back as the 2000 United States presidential election, as well as in the context of fictional political works such as The
The Green Paradox is a controversial book by German economist, Hans-Werner Sinn, describing the observation that an environmental policy that becomes greener with the passage of time acts like an announced expropriation for the owners of fossil fuel resources, inducing them to accelerate resource extraction and hence to accelerate global warming.
The ticking time bomb scenario is a thought experiment that has been used in the ethics debate over whether interrogational torture can ever be justified. The scenario can be formulated as follows: Suppose that a person with knowledge of an imminent terrorist attack that will kill many people is in the hands of the authorities, and he will disclose the information needed to prevent the attack only if he is tortured.
Time travel is the hypothetical activity of traveling into the past or future. Time travel is a concept in philosophy, space, time and fiction, particularly science fiction.
In physics, the twin paradox is a thought experiment in special relativity involving twins, one of whom takes a space voyage at relativistic speeds and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling because each twin sees the other twin as moving, and so, as a consequence of an incorrect and naive application of time dilation and the principle of relativity, each
The unexpected hanging paradox or surprise test paradox is a paradox about a person's expectations about the timing of a future event which they are told will occur at an unexpected time. The paradox is variously applied to a prisoner's hanging or a surprise school test.
In philosophy, the original position is a hypothetical position from which members of society would consider which principles they would select for the basic structure of their society if they had no knowledge ahead of time regarding the position which they would end up occupying in that society. The idea of having no such knowledge, because everyone is behind a veil of ignorance, represents a thought experiment ofte