Unexpected hanging paradox The unexpected hanging paradox, hangman paradox, unexpected exam paradox, surprise test paradox or prediction paradox is a paradox about a person's expectations about the timing of a future event (e.g. a prisoner's hanging, or a school test) which he is told will occur at an unexpected time. Despite significant academic interest, there is no consensus on its precise nature and consequently a final 'correct' resolution has not yet been established.[1] One approach, offered by the logical school of thought, suggests that the problem arises in a self-contradictory self-referencing statement at the heart of the judge's sentence. Another approach, offered by the epistemological school of thought, suggests the unexpected hanging paradox is an example of an epistemic paradox because it turns on our concept of knowledge.[2] Even though it is apparently simple, the paradox's underlying complexities have even led to it being called a "significant problem" for philosophy.[3] Some authors[who?]
Hidden variable theory Albert Einstein, the most famous proponent of hidden variables, objected to the fundamentally probabilistic nature of quantum mechanics,[1] and famously declared "I am convinced God does not play dice".[2] Einstein, Podolsky, and Rosen argued that "elements of reality" (hidden variables) must be added to quantum mechanics to explain entanglement without action at a distance.[3][4] Later, Bell's theorem would suggest (in the opinion of most physicists and contrary to Einstein's assertion) that local hidden variables of certain types are impossible. The most famous nonlocal theory is de Broglie-Bohm theory. Motivation[edit] Under the orthodox Copenhagen interpretation, quantum mechanics is nondeterministic, meaning that it generally does not predict the outcome of any measurement with certainty. In other words, it is conceivable that the Copenhagen interpretation of quantum mechanics is an incomplete description of nature. "God does not play dice"[edit] Bohr-Einstein debates[edit] .
Copenhagen interpretation The Copenhagen interpretation is one of the earliest and most commonly taught interpretations of quantum mechanics.[1] It holds that quantum mechanics does not yield a description of an objective reality but deals only with probabilities of observing, or measuring, various aspects of energy quanta, entities that fit neither the classical idea of particles nor the classical idea of waves. The act of measurement causes the set of probabilities to immediately and randomly assume only one of the possible values. This feature of mathematics is known as wavefunction collapse. The essential concepts of the interpretation were devised by Niels Bohr, Werner Heisenberg and others in the years 1924–27. According to John Cramer, "Despite an extensive literature which refers to, discusses, and criticizes the Copenhagen interpretation of quantum mechanics, nowhere does there seem to be any concise statement which defines the full Copenhagen interpretation. Background[edit] Origin of the term[edit] 1. .
Weird Universe Quantum tunnelling Quantum mechanical phenomenon In physics, quantum tunnelling, barrier penetration, or simply tunnelling is a quantum mechanical phenomenon in which an object such as an electron or atom passes through a potential energy barrier that, according to classical mechanics, should not be passable due to the object not having sufficient energy to pass or surmount the barrier. Tunneling is a consequence of the wave nature of matter, where the quantum wave function describes the state of a particle or other physical system, and wave equations such as the Schrödinger equation describe their behavior. The probability of transmission of a wave packet through a barrier decreases exponentially with the barrier height, the barrier width, and the tunneling particle's mass, so tunneling is seen most prominently in low-mass particles such as electrons or protons tunneling through microscopically narrow barriers. The effect was predicted in the early 20th century. Introduction to the concept [edit] or where .
Ensemble interpretation The ensemble interpretation, or statistical interpretation of quantum mechanics, is an interpretation that can be viewed as a minimalist interpretation; it is a quantum mechanical interpretation that claims to make the fewest assumptions associated with the standard mathematical formalization. At its heart, it takes to the fullest extent the statistical interpretation of Max Born for which he won the Nobel Prize in Physics.[1] The interpretation states that the wave function does not apply to an individual system – or for example, a single particle – but is an abstract mathematical, statistical quantity that only applies to an ensemble of similarly prepared systems or particles. Probably the most notable supporter of such an interpretation was Albert Einstein: To date, probably the most prominent advocate of the ensemble interpretation is Leslie E. Ballentine, Professor at Simon Fraser University, and writer of the graduate-level textbook "Quantum Mechanics, A Modern Development".[3]
70 Reminders to Help You Break Any Barrier I am pleased to introduce this guest article by a new friend John, the creator of HiLife2B, where he hopes to inspire people and to help them achieve their dreams. Follow him on Twitter: @janyasor 1. Believe that even the smallest compliment can save someone’s life 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70.
the childhood beliefs site - I Used To Believe #87: A Superfast Magnetic Shift | Earth Science Every 200,000 years or so, the earth’s poles trade places. Typically it takes several thousand years. But when geologists Scott Bogue of Occidental College and Jonathan Glen of the U.S. Geological Survey examined 15-million-year-old Nevada lava, they found evidence that the planet’s magnetic field shifted several thousand times faster than normal at least once. When lava cools, it locks away a record of the earth’s magnetic field. Examining lavas that cooled in two consecutive years, Bogue and Glen found the field swung 53 degrees from east to north, about 1 degree a week. Bogue thinks the quick shift took place near the end of a millennia-long polarity reversal, when a slow magnetic drift accelerated dramatically for reasons unexplained. Further study could help geologists understand the turbulent motion of the earth’s liquid core, which generates the magnetic field and may initiate its flips.
Objective collapse theory Objective collapse theories are an approach to the interpretational problems of quantum mechanics. They are realistic, indeterministic and reject hidden variables. The approach is similar to the Copenhagen interpretation, but more firmly objective. The most well-known examples of such theories are: Compared to other approaches[edit] Collapse theories stand in opposition to many-worlds interpretation theories, in that they hold that a process of wavefunction collapse curtails the branching of the wavefunction and removes unobserved behaviour. Variations[edit] Objective collapse theories regard the present formalism of quantum mechanics as incomplete, in some sense. Collapse is found "within" the evolution of the wavefunction, often by modifying the equations to introduce small amounts of non-linearity. Objections[edit] The fact that these theories seek to extend the formalism is considered as violation of the principle of parsimony by some. GRW collapse theories have unique problems.
Modality effect The modality effect is a term used in experimental psychology, most often in the fields dealing with memory and learning, to refer to how learner performance depends on the presentation mode of studied items. Description[edit] For serial recall, the modality effect is seen in an increased memory span for auditorally presented lists. Memory span is defined as the maximum number of items that participants correctly recall in 50% of trials. Some studies use the term modality to refer to a general difference in performance based upon the mode of presentation. Bennet Murdock used a basic free recall paradigm, with different types of lists, mixing auditorally and visually presented words. Glenberg[9] showed that the modality effect is also prevalent in long term memory, showing that to-be-remembered word pairs that are separated by distractor activity are better recalled if presented auditorally vs. visually. Several terms have been used to refer to the modality effect on recency.
Is Nuclear Power Safe? - Nuclear Power Safety Myth No. 1 Nuclear Power Isn't a Safe Solution In a recent national poll, 72 percent of respondents expressed concern about potential accidents at nuclear power plants. Some opinion-makers have encouraged this trepidation: Steven Cohen, executive director of Columbia University's Earth Institute, has called nuclear power "dangerous, complicated and politically controversial." During the first six decades of the nuclear age, however, fewer than 100 people have died as a result of nuclear power plant accidents. Power sources such as coal and petroleum might seem safer than nuclear, but statistically they're a lot deadlier. INL nuclear lab's deputy associate director, Kathryn McCarthy, thinks the industry can overcome its stigma.
Consistent histories In quantum mechanics, the consistent histories approach is intended to give a modern interpretation of quantum mechanics, generalising the conventional Copenhagen interpretation and providing a natural interpretation of quantum cosmology.[1] This interpretation of quantum mechanics is based on a consistency criterion that then allows probabilities to be assigned to various alternative histories of a system such that the probabilities for each history obey the rules of classical probability while being consistent with the Schrödinger equation. In contrast to some interpretations of quantum mechanics, particularly the Copenhagen interpretation, the framework does not include "wavefunction collapse" as a relevant description of any physical process, and emphasizes that measurement theory is not a fundamental ingredient of quantum mechanics. Histories[edit] A homogeneous history (here labels different histories) is a sequence of Propositions specified at different moments of time is true at time