What is Paradox: Definition and 1000 Discussions

A paradox is a logically self-contradictory statement or a statement that runs contrary to one's expectation. It is a statement that, despite apparently valid reasoning from true premises, leads to a seemingly self-contradictory or a logically unacceptable conclusion. A paradox usually involves contradictory-yet-interrelated elements that exist simultaneously and persist over time.In logic, many paradoxes exist which are known to be invalid arguments, but which are nevertheless valuable in promoting critical thinking, while other paradoxes have revealed errors in definitions which were assumed to be rigorous, and have caused axioms of mathematics and logic to be re-examined. One example is Russell's paradox, which questions whether a "list of all lists that do not contain themselves" would include itself, and showed that attempts to found set theory on the identification of sets with properties or predicates were flawed. Others, such as Curry's paradox, cannot be easily resolved by making foundational changes in a logical system.Examples outside logic include the ship of Theseus from philosophy, a paradox which questions whether a ship repaired over time by replacing each and all of its wooden parts, one at a time, would remain the same ship. Paradoxes can also take the form of images or other media. For example, M.C. Escher featured perspective-based paradoxes in many of his drawings, with walls that are regarded as floors from other points of view, and staircases that appear to climb endlessly.In common usage, the word "paradox" often refers to statements that are ironic or unexpected, such as "the paradox that standing is more tiring than walking".

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  1. A

    Light travel paradox? Please, help to figure it out

    I need your help to figure it out if the following thought experiment makes sense. Imagine two points in space at the same distance from Earth, 100 light years. At one point a previously unknown supernova explodes; we observe it’s bright light in the sky for several months, and after that it...
  2. bohm2

    Special Relativity and the existence paradox

    Do you find this argument by this author that SR implies "at least one continuum other than our own spacetime" flawed or reasonable? According to the special theory of relativity, observers stationary relative to one another will measure the time in the rest frame of an entity moving relative...
  3. M

    What would happen if entangled particles experienced the twin paradox scenario?

    Okay so everyone is probably familiar with the twin paradox. Basically my question is what would happen if 2 entangled particles somehow underwent a similar scenario? Would they become untangled, or would they remain tangled, and somehow experience time at a different rate then their...
  4. A

    What faster than light have to do with cause and effect paradox ?

    I really can't understand how faster than light travel creates the cause and effect paradox. I have spent many days on internet searching this specific problem but not able to get it. Can some one explain it to me in the easiest way. Another question : i have read many times that...
  5. L

    Can someone explain the resolution to the complex power paradox?

    Hi, Can anyone help me resolve and understand this paradox: e=e^{1+2i\pi} and so e=\left[e^{1+2\pi i}\right]^{1+2\pi i}=e^{1+4\pi i-4\pi^2}=e^{1-4\pi^2} which is obviously fallacious. This paradox is from Roger Penrose Road to Reality and is currently hurting my head. I keep...
  6. A

    How can the uncertainty principle and relativity coexist?

    The uncertainty principle says that you can't simultaneously measure position and momentum with arbitrary precision. So you can measure one at a time t1 and the other at a time t2 with t2 > t1, thus not measuring both simultaneously, but relativity tell us that there exists a frame of reference...
  7. A

    How Does Acceleration Affect Time Dilation in Twin Space Travel Scenarios?

    We think of two very similar scenarios: 1. Two twins are hoovering with their spacecraft s at an earthlike distance A from the Sun and with no velocity with respect to the Sun. Then one of the twins suddenly accelerates to 100 km per second in some direction. He is now the accelerated twin...
  8. A

    What is the outcome of the twin paradox in a new version?

    We think of two very similar scenarios: 1. Two twins are hoovering with their spacecraft s at an earthlike distance A from the Sun and with no velocity with respect to the Sun. Then one of the twins suddenly accelerates to 100 km per second in some direction. He is now the accelerated twin...
  9. K

    Understanding the Parallelogram Area Formula: A Quest for Proof

    Hi there! My question involves the area of a parallelogram. Now, I know how to prove the commonly used formula (b*h) very easily, however, there is a formula given on Wikipedia as an alternative that states...Given two sides B and C with angle (theta), B*C*sin(theta)=Area of a parallelogram. Now...
  10. J

    Is the Paradox Day Paradox Real?

    I got this problem from one of my favorite webcomics: Paradox occurs on a random day during the year such that it is unexpected which day it is. This precludes paradox day from occurring on December 31st since on December 30th we would know it had to occur the next day. Likewise, since paradox...
  11. Y

    Accelerating spaceship paradox

    Hi, Please consider: At time zero a spaceship takes off from Earth and keeps traveling under constant acceleration. From Earth's perspective, the spaceship's speed keeps increasing but never reaches c. Also from Earth's perspective, the clock on the spaceship keeps slowing down and...
  12. A

    How Does Time Dilation Explain the Twin Paradox?

    Hello, I was talking with my Physics professor the other day about something I could do in Special Relativity, since I'm only in Physics III and haven't experienced much of it, yet find it very interesting. He mentioned that I could do stuff with the Twin Paradox. Now I know the basic idea...
  13. J

    Unveiling the Belt Paradox: Exploring Interferometrics Cart Phenomenon

    Interferometrics Cart Imagine that a cart is mounted with two electric motors, connected each to a pulley. Between the pulleys is installed a belt of equidistant holes that always coincide at the same points in relation to the cart. This allows the passage of luminous flux. Like a...
  14. N

    Set-Theory, a paradox from Zeno and Russell/Cantor confusion.

    I can't come to a comfortable conclusion which doesn't make positive, negative, real, imaginary, complex, irrational or transcendental numbers seem much different fundamentally. Zeno (to the best of my interpretation) illustrates a large part of my problem with: "If there are many, they...
  15. J

    Twin Paradox with no asymmetry

    Twin "Paradox" with no asymmetry Here is another variation of the twin paradox. Suppose we let both twins start their journey from a space station far from any heavenly bodies, so that the whole experiment can be carried out in free space. The twins Jack and John are equipped with identical...
  16. fluidistic

    Understanding Time Dilation: The Paradox of Aging in Outer Space

    I've thought about something that is a paradox to me. I think I know what would happen in reality but I can't explain why the other option is discarded. Imagine you are an observer that can live "forever". You are over the Earth and looking toward the Sun. For the sake of simplicity, let's...
  17. A

    More thoughts on the twin paradox. One persons view has to be an illusion?

    Everyone knows the situation. The one twin takes off in a rocket, and both twins see the others clock as running slow. Upon the return, its the one who has experienced acceleration that ends up being incorrect. So at some point, the "moving" twins view must show time on his brothers Earth clock...
  18. N

    Bullet-hole Paradox: Train Frame & Stopped Train Measurements

    Bullet-hole "paradox" This is a variant of the so-called "bullet-hole paradox" (the guns can be lasers and the train a spaceship): Two guns are mounted a distance of 40 ns apart (SR unit system) on the embankment beside a railroad track. The barrels of the guns project toward the track so...
  19. R

    Help resolving absolute motion paradox please.

    Hi, I’ve been teaching myself SR, currently reading Relativity for the Questioning Mind by Daniel F Styer. My math is not great, so I have been avoiding the heavy calculations for now. I will learn those too, but I wanted to understand the concepts first. For the most part I think I have...
  20. C

    Question about the Banach–Tarski paradox.

    I was reading a little bit about the Banach–Tarski theorem. Is this similar to a line segment of length 1 having the same points as a square with side lengths of 1. And then also a cube with sides of length 1. So then I should be able to take a square and pick out all the points and construct a...
  21. B

    Is the Twin Paradox Truly Unsolvable?

    can twin paradox be solved,if no, what r the difficulties scientist face to solve it?? or is there a solution on it.
  22. D

    Exploring the Paradox of Relativity's Speed of Light

    I'm a relative newbie to relativity (no pun intended -- I know you've heard that one too many times), as well as to this forum, so forgive me if this is a dumb question... As I understand it, there is a significant percentage of those that believe that people, spaceships, etc. will never travel...
  23. E

    Need help resolving this paradox with time dilation

    Before I post this, I want to assure everyone that I am not a conspiracy theorist who doubts Einstein or relativity theory in any aspect. I just don't understand special relativity as well as Id like to and I think having this paradox resolved in my mind will help. The paradoxes that I've...
  24. M

    Paradox: The infinite square well vs. the Uncertainty Principle

    I've come across an apparent paradox in elementary quantum mechanics, and after a little Googling, haven't found a reference to it. Here goes, The 1-D infinite square well is a classic problem in introductory QM. We find that the position-space eigenfunctions of the Hamiltonian (the "allowed...
  25. S

    Hydrostatic paradox one step further- weights of the different fluid amounts

    Homework Statement Two open-top containers, #1 on the left and #2 on the right, with equal base area A are placed on two scales. The #2 container on the right has an lower diameter twice that of its upper diameter and the height of its lower (larger) diameter is half that of its water height...
  26. 0

    A paradox in commutation relation

    The following paradox was put forward by "Fredrik" in a discussion on "time-uncertainity relation"- Lets look at this closely, using position momentum operators and a general quantum state- \langle U|xp - px|U \rangle This can be rewritten as- \sum_{x'}\sum_{x"}\sum_{p'} (\langle...
  27. S

    How is twin paradox resolved in case of no/zero acceleration?

    how is twin paradox resolved in case of no/zero acceleration/deceleration? two twins one on Earth and other on a ship moving at constant velocity (say 80% speed of light). the other twin does not turn around ..thus no acceleration/deceleration. how we resolve the paradox now? twin A will say...
  28. B

    Olbers' paradox - Poisson model

    Olbers' paradox states that if the universe is infinite, static and homogeneous then why is the night sky dark. Of course it's been resolved but it brings up an interesting probability question: If we model the universe with a spatial Poisson model (probability that a small element is...
  29. D

    Paradox for the existence of 4,5 and 7 using Brocard's problem

    I have attatched my Paradox for the existence of 4,5 and 7 using Brocard's problem . I don't know where i have gone wrong as 4,5,7 exist, surely.
  30. S

    The Final Solution of the Liar Paradox

    Let us check the derivation of the liar paradox. 1 Sentence 1 is not true. (Assumption 1) (LIAR SENTENCE) 2 Sentence 1 = "Sentence 1 is not true) (True by inspection of 1) (LIAR IDENTITY) 3 "Sentence 1 is not true" is true if and only if sentence 1 is not true (by definition of truth)...
  31. C

    Solving the Paradox of Quantum Mechanics & Special Relativity

    Introduction: (can be skipped) We know the problems around the collapse of the state (specially that we don't know how an outcome is selected from the preferred states). Now thousand of experiments shows us that this strange not unitary transformation of the states occurs when a measurement...
  32. W

    Ohm's Law and AC Power: Explaining the Paradox

    I am confuse at a point that is: I equation P=IV there is an inverse relation between I and V But according to ohm law there is direct relation between I and V. How in in ac Power transmission line 1100 volt cause small current than 220 volt... please solve my this trouble... Everyone...
  33. H

    What happens when the rope goes off hook?

    Hi all. Suppose we have two objects A and B, and suppose we tie a rope R to the objects with the rope R's two edges hooked to a pole or hook on each of the objects. The rope is loosely connected to the hooks on such a way that as objects will move away from each other, then as the rope will...
  34. C

    What time does an observer see when watching a clock on a rotating circle?

    Hi, I'm new here. This question may already have an answer but I didn't find it. Sorry if there's already one. It's a static version of the twin paradox, without travel and without twins. We have 2 circles C and C' that are superposed. C is fixed, with time t and co-ordinate x along the circle...
  35. G

    Exploring the Paradox of Movement: Is it Possible?

    i'm trying to conclude on HOW this would be possible... though its a paradox doesn't it seem very possible? in case you don't know what it is its saying movement is immpossible. Example to get from point a to point b you have to go halfway but before you get from point A to A1/2 you have to get...
  36. D

    Understanding Russell's Paradox: The Paradox of Self-Referential Sets

    1. Russell's paradox is: A={x:x∉x} Is A a subset of itself? But my question is: Let there be a set M such that: M={1,2,3,4} The now, one asks if M is a subset of itself. Most probably he would hear a know but, since M={1,2,3,4} and again I write here M={1,2,3,4}, {1,2,3,4} can be...
  37. G

    Is the speed of light a paradox?

    If observed time approaches 0 at the speed of light, does that mean the distance one travles at the speed of light is infinite? Since speed = distance/time, does this mean that, at the speed of light C= infinity/0 which = 0? There then appears to be no speed at the speed of light. Does this...
  38. B

    How would a trampoline solve the twin paradox in relativity?

    So we have covered relativity a couple weeks ago and I've been thinking about the twin paradox. It is when one twin travels on a high speed ship to some distant planet and back. But since all frames of reference are equivalent, each twin measures the other to be younger. My book explained that...
  39. Grinkle

    Black hole growth paradox question

    Are the two following hypothetical observations contradictory according to GR? 1. Particles fall towards a black hole but never cross the event horizon 2. After observing this for a few million years, the mass of the black hole is observed to have grown over that few million years. Or...
  40. V

    Time dilation and twins paradox

    "The confusion that arises in problems like Example 26.1 lies in the fact that movement is relative: from the point of view of someone in the pendulum’s rest frame, the pendulum is standing still (except, of course, for the swinging motion), whereas to someone in a frame that is moving with...
  41. H

    Question relating to the Ehrenfest Paradox

    My question relates to the “Ehrenfest paradox”. I try to grasp it. “In its original formulation as presented by Paul Ehrenfest 1909 in the Physikalische Zeitschrift, it discusses an ideally rigid cylinder that is made to rotate about its axis of symmetry. The radius R as seen in the...
  42. K

    Twin paradox alone kills special relativity

    twin paradox alone kills special relativity: the story: A stays on the planet, B round-travels by spaceship; when back, based on spectral relativity, B youngs. analysis: when special relativity is be applied, the property difference between planet and spaceship is never used; so...
  43. B

    Time Dilation - Is this a paradox?

    [PLAIN]http://www.science27.com/forum/rocketL2.jpg Above the head of observer “A” a mother-ship is moving east 100,000 km/s. and right above the Earth it is launching a small spacecraft moving west with the same speed (100,000 km/s). REFERENCE FRAME A Observer “A” would now (from...
  44. K

    Wave Vectors of Light vs. Phonons: A Puzzling Paradox

    In his paper, "Radiative exchange of heat between nanostructures" Pendry makes this statement : "In general phonons have much smaller wave vectors at a given frequency than does light " Isn't wave vector given by 2*Pi /Lambda? So how can wave vectors be smaller for phonons than for...
  45. R

    Is Planck's constant a paradox?

    The following is a quote from Wikipedia on Irrational Numbers (the bold is mine): If this is the case and there is no "small indivisible unit that could fit evenly into one of these lengths as well as the other", then how can Planck's Constant be true, unless it is a paradoxical number that is...
  46. V

    Relativity of Simultaneity: A question about the train paradox

    Hi, I was reading the book "Spacetime Physics" by Taylor/Wheeler. In their discourse on the relativity of simultaneity, the example they have used is Einstein's Train Paradox. See and also the attachment for the Train Paradox. My question is this: The analysis of what the train observer(TO)...
  47. S

    Room in Spaceship: Apparent Paradox?

    Imagine a room in a spaceship. At each end, a laser is set up that points toward the center. At the center of the room there is a double-sided light detector that is connected to a switch. When the switch is flipped, it completes a circuit which causes a light-bulb to turn on. If both laser...
  48. P

    Twin Paradox in Relativity: Examining Motion, Time and Distance

    According to what I have researched in Relativity (thanks to you guys) there is no such thing as absolute motion, time, or distance. I had a question about this paradox mentioned. Paraphrase: Two people that are exactly 20 years old are on earth. One decides to fly to planetX and some...
  49. J

    What's the Secret Behind the Geometry Paradox of Increasing Triangles?

    Check it out: http://imgur.com/EpYQv Where's the trick?
  50. A

    Resolving the EPR Paradox: Exploring Signal Models and Special Relativity

    We consider a typical version of the EPR paradox where an electron and a positron are produced collinearly in the +y and -y with the spins polarized in the positive and negative z directions. The pair is emitted with zero linear and zero spin-angular momentum. If the positron is detected in the...
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