What is Copenhagen: Definition and 70 Discussions

Copenhagen (Danish: København [kʰøpm̩ˈhɑwˀn] (listen)) is the capital and most populous city of Denmark. As of 1 January 2020, the city had a population of 794,128 with 632,340 in Copenhagen Municipality, 104,305 in Frederiksberg Municipality, 42,989 in Tårnby Municipality, and 14,494 in Dragør Municipality. It forms the core of the wider urban area of Copenhagen (population 1,336,982) and the Copenhagen metropolitan area (population 2,057,142). Copenhagen is situated on the eastern coast of the island of Zealand; another portion of the city is located on Amager, and it is separated from Malmö, Sweden, by the strait of Øresund. The Øresund Bridge connects the two cities by rail and road.
Originally a Viking fishing village established in the 10th century in the vicinity of what is now Gammel Strand, Copenhagen became the capital of Denmark in the early 15th century. Beginning in the 17th century, it consolidated its position as a regional centre of power with its institutions, defences, and armed forces. During the Renaissance the city served as the de facto capital being the seat of government of the Kalmar Union, governing the entire present day Nordic region in a personal union with Sweden and Norway ruled by the Danish monarch serving as the head of state. The city flourished as the cultural and economic center of Scandinavia under the union for well over 120 years, starting in the 15th century up until the beginning of the 16th century when the union was dissolved with Sweden leaving the union through a rebellion. After a plague outbreak and fire in the 18th century, the city underwent a period of redevelopment. This included construction of the prestigious district of Frederiksstaden and founding of such cultural institutions as the Royal Theatre and the Royal Academy of Fine Arts. After further disasters in the early 19th century when Horatio Nelson attacked the Dano-Norwegian fleet and bombarded the city, rebuilding during the Danish Golden Age brought a Neoclassical look to Copenhagen's architecture. Later, following the Second World War, the Finger Plan fostered the development of housing and businesses along the five urban railway routes stretching out from the city centre.
Since the turn of the 21st century, Copenhagen has seen strong urban and cultural development, facilitated by investment in its institutions and infrastructure. The city is the cultural, economic and governmental centre of Denmark; it is one of the major financial centres of Northern Europe with the Copenhagen Stock Exchange. Copenhagen's economy has seen rapid developments in the service sector, especially through initiatives in information technology, pharmaceuticals and clean technology. Since the completion of the Øresund Bridge, Copenhagen has become increasingly integrated with the Swedish province of Scania and its largest city, Malmö, forming the Øresund Region. With a number of bridges connecting the various districts, the cityscape is characterised by parks, promenades, and waterfronts. Copenhagen's landmarks such as Tivoli Gardens, The Little Mermaid statue, the Amalienborg and Christiansborg palaces, Rosenborg Castle Gardens, Frederik's Church, and many museums, restaurants and nightclubs are significant tourist attractions.
Copenhagen is home to the University of Copenhagen, the Technical University of Denmark, Copenhagen Business School and the IT University of Copenhagen. The University of Copenhagen, founded in 1479, is the oldest university in Denmark. Copenhagen is home to the F.C. Copenhagen. The annual Copenhagen Marathon was established in 1980. Copenhagen is one of the most bicycle-friendly cities in the world.
The Copenhagen Metro, launched in 2002, serves central Copenhagen. Additionally, the Copenhagen S-train, the Lokaltog (private railway), and the Coast Line network serve and connect central Copenhagen to outlying boroughs. Serving roughly two million passengers a month, Copenhagen Airport, Kastrup, is the busiest airport in the Nordic countries.

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  1. Jacob Peters

    B Copenhagen Interpretation - Superposition - confirmed?

    Hi, From what I read here, they did a double slit experiment test with neutrons that seemed to confirm superposition that the particle was in both places at once. Thoughts?
  2. M

    I Input on a basic Copenhagen question

    As if you couldn't guess from the question, I'm very much a layman wrt physics, but here it is anyway: I've read a number of (non-technical) books on quantum physics but I can't seem to find much - indeed anything at all - on the role of time in collapse of the wave function when considering...
  3. entropy1

    I Deterministic wind down of the Universe under MWI or Copenhagen?

    Is it correct to say: Under the Many Worlds Interpretation: If we rerun the universe repeatedly from the same state S(0), it winds down the same way each time, which is determinism; Under the Copenhagen Interpretation: If we rerun the universe repeatedly from the same state S(0), it may well...
  4. entropy1

    B Copenhagen Interpretation and collapse moment

    Is it still true that under the Copenhagen Interpretation the standard theory of QM tells us that a measurement apparatus gets into superposition of possible measurement outcomes and does not tell us how and when we get a single decisive outcome? (The so-called "Measurement problem")
  5. Lynch101

    I Exploring QM Interpretations: Copenhagen & Blockworld

    Reading the very interesting thread that @Demystifier started, I was hoping to get a better understanding of certain ideas. I don't think these questions would be suitable for that particular thread. The first such question pertains to the following exchange between DarMM and Demystifier. Are...
  6. D

    I What is the Copenhagen interpretation according to its originator(s)?

    I feel that contemporary authors' statements about the copenhagen interpretation don't really match with what the founders of quantum mechanics said. Also, different authors give seemingly contradictory statements about it is. What do the members here think about this? What is the copenhagen...
  7. entropy1

    I Probability in MWI and the Copenhagen interpretation

    Suppose we have an operator with three eigenvectors/eigenvalues ##e_1##, ##e_2## and ##e_3##. The operator measures wavefunction ##\psi##. Could we say that we find outcome ##e_x## with probability ##P(\psi,e_x)##, and could we extend this to an infinite dimensional operator as a spectrum of...
  8. johnconner

    I Copenhagen interpretation & Delayed-choice quantum eraser

    For explaining Delayed-choice quantum eraser experiment, what if I change the Copenhagen interpretation a little. When the experiment is concluded, we observe one detector (the first detector with the shortest path) has detected the pattern long before the wavefunction is collapsed (before the...
  9. LCSphysicist

    I What are current Physicists' general positions on the Copenhagen Interpretation?

    Actually, is not a doubt as a question, in which there is wrong or right. I just want to update myself with respect to the current physicists opinion about the Copenhagen interpretation of Bohr and Heisenberg. Summarizing, there is a consensus among the majority? In another words, there is still...
  10. Lynch101

    I For and Against the Copenhagen Interpretation

    Given the various different interpretations of quantum mechanics, I am interested in getting a general overview of most/all of them. I think it would be interesting to hear what people list as the positives of each interpretation as well as issues they perceive with each. I was thinking that, if...
  11. Demystifier

    I A Copenhagen solution of the black hole singularity problem

    Due to strong gravitational tidal forces, any living observer will die and any macroscopic measuring apparatus will be destroyed before it reaches the black hole singularity at the center of a macroscopic black hole. Hence the black hole singularity cannot be observed, so from an experimental...
  12. M

    I Qbism vs Copenhagen: What is the Difference?

    I read a few articles about Qbism, but feel like I don't understand the difference from Copenhagen. One author claims the difference is that each observer has his own view of the world (and own probabilities in qbism). I thought that was also the case in Copenhagen. E.g. the old Wigner's...
  13. mollwollfumble

    A Bohr's contribution to the Copenhagen interpretation

    I wish to learn about Bohr's contribution to the Copenhagen interpretation by reading his original papers on QM, preferably in English. Which papers are most important?
  14. J

    I Copenhagen and Decoherence

    Something puzzling and inconsistent. Decoherence was supposed to remove the need for observers in Copenhagen. But how come Lee Smolin didn't discuss anything about decoherence with regards to the Copenhagenists but only the Everettians in his book "Einstein Unfinished Revolution: The Search for...
  15. Demystifier

    A Copenhagen: Restriction on knowledge or restriction on ontology?

    The title of this thread is motivated by frequent arguments I had with other members here, especially @DarMM and @vanhees71 . The so called "Copenhagen" interpretation of QM, known also as "standard" or "orthodox" interpretation, which is really a wide class of related but different...
  16. J

    I Quantum Suicide: Exploring Copenhagen & Many Worlds Interpretations

    Is it possible to modify the original quantum suicide experiment in a way in which rather than dying you are put to sleep for someone to distinguish between many worlds and Copenhagen interpretations?
  17. MichPod

    I What has changed since the Copenhagen interpretation?

    If to look at the foundations of QM and if to ignore various not much verifiable alternative interpretations of QM which emerged since the Copenhagen, starting with Bohm and Everett, what are the commonly accepted and recognized changes to the original views of the QM creators? There are planty...
  18. PeterDonis

    Insights The Fundamental Difference in Interpretations of Quantum Mechanics - Comments

    Greg Bernhardt submitted a new PF Insights post The Fundamental Difference in Interpretations of Quantum Mechanics Continue reading the Original PF Insights Post.
  19. B

    News Have you visited the LHC in Copenhagen?

    With so much terror attack in Europe like London, Belgium, Madrid, etc. and shooting, violence, mob attack in the United States and elsewhere.. Copenhagen seems to be one of the safest place on Earth (agree?). Has anyone visited Copenhagen? Is Bohr house still there? Have you gone inside it? It...
  20. durant35

    I Can entropy drop in the Copenhagen interpretation?

    I've been reading some speculative articles about the possible quantum arrow of time which emerges through collapse and irreversibility. My question is: does collapse in the Copenhagen interpretation (or perhaps in a objective-collapse model) allow the spontaneous decrease of entropy where an...
  21. N

    I Is there a psi ontic Copenhagen interpretation?

    Is there a psi ontic version of the Copenhagen interpretation ( where the wave function is regarded real)? Can the wave function be real in Copenhagen interpretation?
  22. hsdrop

    Does the Copenhagen interpretation require consciousness for the same outcome?

    does it matter if a person or a computer looks at the result I guess I'm asking if something needs consciousness to have the same outcome in the case that I'm not making any sense please ask and I will try to seaplane in more detail and thank you for anyone that respons
  23. entropy1

    Do CI and MWI Interpret Quantum Probabilities Differently?

    Suppose we fire a photon P at a polarisation filter F1, and it passes the filter, thus forcing the polarisation of P in an eigenstate M1. Subsequently, the photon falls through a polarisation filter F2, forcing P in eigenstate M2. Now, if I understand correctly, the probability of P passing F2...
  24. D

    Copenhagen interpretation and entropy confusion?

    I don't see how the Copenhagen interpretation and the second law of thermodynamics can be compatible. In the Copenhagen interpretation, upon losing coherence the system chooses a single definite state and all other possible states are eradicated. This seems to be losing entropy to me, as it's...
  25. A

    Can decoherence validate the Copenhagen interpretation?

    Hi, I am an amateur enthusiast and this is a direct question (not a proposal, I'm not nearly qualified to offer a proposal). I would like to throw to experts and people who are more qualified, because it's got me a bit stumped. Could I ask for an answer which is as simple as I am please, lols -...
  26. S

    Is Copenhagen interpretation a collapse theory?

    I have been learning about the different interpretations of QM, and I am trying to build a taxonomy of them in my mind (I find that trying to build taxonomies is a good way of learning about things). I have read about collapse theories and non-collapse theories. If I have got this right, the...
  27. Jesayntly

    Copenhagen - What qualifies as "measurement" and "observer"?

    Hey guys and gals, clearly I'm new here, not only new here but new to QM (relatively speaking). I've read a few threads here pertaining to a thought I've been pondering on but the answer doesn't seem clear. In the Copenhagen interpretation, what qualifies as a "measurement", and/or what...
  28. 1977ub

    Copenhagen Interpretation of Sleep / Unseen brain?

    What is the accepted interpretation of these two similar related issues: 1) When I am sleeping do my brain and body revert to un-collapsed wave state until and unless seen by a different observer? 2) I *never* have "seen" my brain - have the wave functions of the atoms and cells collapsed?
  29. N

    What Distinguishes Neo-Copenhagenism from the Copenhagen Interpretation?

    Is it the same thing as the copenhagen interpretation, what's different about it?
  30. N

    Question about copenhagen interpretation

    Does the Copenhagen interpretation allow for particles(electrons) to be in more than once place at the same time. I am not talking about quantum superposition here. I'm asking if it allows for electrons to be in many places at once like the many worlds interpretation does.
  31. J

    Living Opponents of the Copenhagen Interpretation

    I was wondering if anyone could tell me who are considered the leading opponents of the Copenhagen Interpretation who are alive today?--and even what would be the best way to get myself some formal physics education under such individuals? I would love to learn more about physics, although I...
  32. noir1993

    Books on Interpretations of Quantum Mechanics

    What are some good textbooks dealing with various Interpretations of Quantum Mechanics? I am not asking for popular science books. I have a book called 'Understanding Quantum Mechanics' by Ronald Omens on the consistent histories approach and I am looking for something like that.
  33. P

    A question regarding the Copenhagen interpretation.

    hi guys, i just have a quick question concerning the Copenhagen interpretation of things. say there is a star, very far away (perhaps 1 billion light-years from Earth) that for the sake of this idea, has never been observed, by any intelligent being, anywhere. we happen to turn our telescope...
  34. A

    Copenhagen Interpretation vs Instrumentalism

    For 2 years now I have been reading posts at my university student forums about how the Copenhagen Interpretation is redundant because ensemble physics is the equivalence of CI and it is ensemble that is used in day to day physics. While I sympathize with applied physics and engineering I just...
  35. Greg Bernhardt

    Engineering the Copenhagen Wheel: Revolutionizing Biking?

    Looks pretty awesome! Any thoughts from a engineering standpoint? Could it revolutionize biking? https://www.youtube.com/watch?v=S10GMfG2NMY
  36. H

    Copenhagen Suborbitals open source space travel

    Very interesting bunch of guys trying to get a man into suborbit as cheap as possible. Found their website and youtube videos links at the bottom. Thought I would share. They have interesting video's of engine tests as they try to design the first rocket to send a man into space...
  37. T

    Can Quantum Mechanics be studied without the Copenhagen interpretation

    Hello everyone, I'm a doctoral student of particle physics in ETH Zurich, and have a question in fundamental QM. I remember a friend telling me that the professor that taught him Quantum Mechanics in ETH Zurich did not believe in the Copenhagen interpretation, and thus taught the class...
  38. Filip Larsen

    Copenhagen Suborbitals performs sea launch of guided rocket

    The danish rocket group Copenhagen Suborbitals are scheduled to perform a sea launch of their first guided rocket, the 5.3 m long http://www.copenhagensuborbitals.com/contentgfx/Sapphire_specs.pdf, on Sunday, June 23th at around 9:00 UTC (11:00 CEST, 05:00 EDT, 02:00 PDT) from the test range ES...
  39. Monique

    News CNN reporter thinks Copenhagen is the capital of the Netherlands

    I thought CNN was a reputable broadcaster, but then a reporter standing on the Dam square in Amsterdam says "you have people from all over the Netherlands coming here, to Copenhagen, to have a great time" (to celebrate the new king). Really, CNN?
  40. G

    Understanding the Copenhagen Interpretation

    This is from Wikipedia regarding the first point of the Copenhagen Interpretation: What does it mean to make a measurement? Is this something that only living beings do or can a dead particle make a measurement? Why does measurement collapse the wave function.
  41. A

    Copenhagen interpretation of Big Bang

    How old was the universe when the first wave function collapsed? Just wondering. I've checked all the FAQs on this, and the one hit in Google doesn't really cover it from a cosmological angle. I see there is a "Participatory Anthropic Principle" but my question is really more about, well, how...
  42. Filip Larsen

    Copenhagen Suborbitals to perform double sea launch of SMARAGD Friday at 08 UTC

    According to the latest status and weather reports, the danish amateur rocket group Copenhagen Suborbitals [1] is still go for a sea launch of one or both of its two-stage SMARAGD hybrid rockets in the expected launch window Friday, July 27 at 08 to 12 UTC [2]. The first launch will be...
  43. R

    Arrow of time in copenhagen interpretation.

    Most physicists don't draw a distinction between past, present and future.. this is called the arrow of time. Physicists such as Sean caroll, Paul Davies e.t.c But if all events exist in some sense then the future is <not> open. If the future is not open then determinism is true.. thus...
  44. S

    Understanding the copenhagen interpretation

    This is an extract from the lecture notes I took for the 'Foundations of QM' third year course. Copenhagen QM - classical-quantum division State: wavefunction ψ(x); (ψ,\varphi) = \int d^{3}r ψ^{*}(r)\varphi(r) Evolution: TDSE Observables (\hat{x},\hat{p},\hat{H}): A = A-dagger...
  45. R

    What is the difference between the Copenhagen Interpretation and Quantum Theory?

    They say Copenhagen Interpretation is not Shut Up and Calculate. So what really is Copenhagen Interpretation. What is its belief and statements? And how many percentage of physicists just focus on Quantum Theory and not care about interpretations and how many of them are into Copenhagen?
  46. A

    MWI vs Copenhagen Interpretation

    I recently read an article entitled, "The Interpretation of Quantum Mechanics: Many Worlds or Many Words?" authored by Max Tegmark and it raised many questions on the matter as well as curiosity. In the article, Tegmark provides two tenable but diametrically opposite paradigms regarding physical...
  47. E

    Multiverse vs Copenhagen, John von Neumann

    According to John von Neumann’s interpretation of QM, consciousness is why the wave function collapses. Copenhagen is on the same general idea, but does not mention it that categorically. Multiverse interpretation of QM says there is no wave function collapse, therefore the observer or...
  48. D

    More Support for The Copenhagen Interp.

    What do ya'll make of this: http://www.newscientist.com/article/dn20600-quantum-magic-trick-shows-reality-is-what-you-make-it.html "It appears that you can't even conceive of a theory where specific observables would have definite values that are independent of the other things you...
  49. V

    Is Copenhagen the pragmatic or actual interpretation of quantum theory?

    How many percentage of physicists believe Copenhagen is pragmatism and how many percentage believe Copenhagen is actual in that the particles attributes are really nonexistent before measurement? Quoting Herbert in Quantum Reality: "Some physicists confuse the Copenhagen doctrine with a...
  50. B

    Copenhagen and Ontological (Bohm) insterpretations

    Homework Statement Briefly compare and contrast the Copenhagen and Ontological interpretations with reference to the two slit experiment and the role of wave particle duality. Give four unique points. Homework Equations N/A The Attempt at a Solution I already have rough draft, I...