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".
Consider two concentric circles of radius r1 and r2 as might be drawn on the face of a wall clock. Suppose a uniform rigid heavy rod of length
| r2-r1 |
is somehow constrained between these two circles so that one end of the rod remains on the inner circle and the other remains on the...
if two equal capacitor one of then is charged and the other is not.then the switch is closed, half of the stored energy of the 1st capacitor will be lost.
if there is a way to move electrons from one of the positive plates to the other positive of the other capacitor,will it require less...
Optics would predict that objects appear bigger in size as higher the redshift and the density should be the same independent of the galaxys redshift.
As far I know this is not supported by observations. Anybody has an explanation please?
sdgs_cat
I need your opinion/help, guys.
Well-know American logician H. Curry once expressed the opinion that in spite of the fact that it seemed to be absolutely impossible to explain Russell's paradox in terms of conventional 19th century logic, it may happen in modern days that some error would be...
Homework Statement
Does anybody have any idea about magnetic paradox.i saw a university question where they asked to write a short note on it.i searched google , griffiths, jackson , feynman.all my search has gone in vain.i am doing bsc hons in physics and in my 2nd year course of studies...
http://en.wikipedia.org/wiki/Ladder_paradox#Man_falling_into_grate_variation
In the resolution it says: "It should be stressed that, since this bending occurs in the rod's rest frame, it is a true physical distortion of the rod which will cause stresses to occur in the rod."
I wonder if...
Hi,
I did a search for "crackpot physics" and found https://www.physicsforums.com/showthread.php?t=111647 and then this forum.
A friend of mine found some strange twins paradox on the net but he can't remember where.
Neither of us can figure out the solution, but it must be crackpot...
Let T be an operator on the vector space V and let λ1, ... , λn be it's eigen values including multiplicity .
Lets find the eigen values for the operator T*T then ( where T* refers to the adjoint operator . <u,v> denotes inner product of u and v )
< Tv , Tv > = < λv, λv >
=...
We all know that whenever an object is subjected to move against a conservative force field by an external agent,work should be done to do that.Let that work be W(applied). This is stored as Potential energy of the system.
If F is conservative force acting on a body and if we move that body...
seems to be a "paradox" in galilean relativity
Hello
I'm having a little bit of trouble with so-called rest frames. I will distinguish two cases.
consider frame S, and a particle moving along the x-axis at speed v.
Case I: consider the rest frame S' traveling along with x at speed v...
Four boys: Alfredo, Bucky, Declan, and Franklin.
They're on an island (with lots of beautiful girls!).
Alfredo likes looking at beautiful bikini-clad girls. He settles on the beach.
Bucky hops in a spaceship.
Declan hops in another spaceship.
Franklin hops in a machine attached to the...
The first thing we learn in relativity is that what we measure is relative motion, i.e., with respect to a particular frame of reference. The values of position, velocity, acceleration differs with the frame of reference chosen.
When we go on, we come across time dilation. The theory mentions...
I'm having a bit of a problem getting my head around Olber's paradox. The explanations haven't convinced me (I'm sure the fault is with me). According to Wikipedia:
"To show this, we divide the universe into a series of concentric shells, 1 light year thick (say). Thus, a certain number of...
Triplets, three boys.
Assume all this happens on the same day and at the same time.
Boy A: leaves Earth in vessel going .9c in zig-zag directions for thirty days. Returns to earth.
Boy B: leaves Earth in vessel going .9c but goes in straight line (15 days), turns around and returns to Earth...
I watched this documentary about an argument involving information loss in a black hole, Stephen Hawking managed to wind everybody up by claiming information was lost and therefore broke existing laws of physics.
Its an old recording so it may not be relevant anymore but one part of this...
we can see from length contraction of inclined bodies to the velocity,
consider situation in figure.A spaceship is moving with respect to observer 1 at velocity V.
as shown in the diagram,the observer inside observs length equal to PQ.
the observer outside observes length to be PS .
if this is...
suppose a rigid ball roll on a rigid level with constant velocity , the friction on the contact surface decrease the forward velocity but increase angular velocity ,
how do you explain this paradox?
Disclaimer: I am relatively illiterate on the subject so please try to keep explanations generally understandable. Aerospace undergrad programs get zero exposure to relativity I suppose.
[Gravitational Time Dilation]
First I want to know if I am correct in saying that the gravitational...
Look inside the paint doc.
My question is why does the paragraph say ...A positive charge q gains kinetic energy as it falls towards the negative plate...
However the graph shows that the positive charge q loses kinetic energy...
I am confused what am I not understanding?
Suppose you have two people who are in identical orbits around a large star. The only difference between them is the direction they are traveling. At a certain point where they meet ( there are two such points ), they sync clocks.
After a few orbits, they meet again and again compare clocks...
For a free particle stationary state, one would expect the expectation values are constants, for example, <x> (t) = 0. From its one dimensional wave function psi(x,t)= exp(ipx/h-iEt/h)/L^1/2, <x> is undefinied (or zero since x has odd parity).
How does one reconcile the above with Ehrenfest's...
Homework Statement
Suppose that Hilbert's Grand HOtel is fully occupied on the day that the hotel closes all the even numbered rooms for maintenance. Show that all guests can remain at the hotel
Homework Equations
The Attempt at a Solution
I am not quite sure how to solve this, my...
Homework Statement
Suppose you choose a random family with two children. One of them is a
girl. What is the probability that both children are girls?
Derive your answer by explicitly constructing an outcome space and a probability
measure, and naming the relevant events in terms of this...
Well its a paradox to me haha. If light has a maximum speed but yet every one object in the universe is moving relative to another... 1. Wouldnt I technically be moving at the speed of light since the light emitted from my iphone are zooming past me at 300,000,000 m/s?
2. If no, then there...
Hi, my first post on the forums. I've known about twin paradox for a while, so when we learned special relativity at school in September, it wasn't anything weird. Math is elegant, unlike quantum physics. But a few weeks ago, I started wondering something. It might be just an ordinary logical...
Hi!
I am not much of astrophysicist or something but read something about Black hole information paradox in a book. Could anybody please explain me what is the meaning of term and why does it happen?
P.S. Please include Hawking's radiation as well
Thank you in advance
Personally I don't believe that paradox's can exist in nature, it just means something has been missed.
Senario - we will use a velocity where 1 year in space = 10 years on earth. The Earth will be our control clock. The space traveller just has to be able to see the earth, in orbit if this...
I was studying the twin paradox (of Einstein special relativity) and everything was working well until I get to the traveler's spacetime diagram.
First let me introduce the paradox for you to understand the diagram.
Pam is the twin sister of Joe. Pam goes out Earth in 2007 in a spaceship...
Description of the paradox:
We have a charged ring, which rotates at high speed. Since rotating charges produce cyclotron radiation, it emits photons. There is a toroidal mirror around the ring, spinning together with it. The mirror reflects the photons back inside, preventing them from...
Homework Statement
We are given that there are two hospitals A & B.
Each hospital has two separate wards: one for low-risk patients (LR) and one for high-risk patients (HR.)
Hospital A had 120 patients total and cured 60 total. (.5 cure rate)
Hospital B had 700 patients total and cured...
I'm not sure if this belongs here or in Cosmology - possibly either would do, I think. I was reading the thread about open/closed/flat universes that's currently ongoing in Cosmology, and a related question occurred to me.
According to post #7 you can have geometrically flat universes that...
Imagine two bodies A & B. they have same mass and same speed, but they are traveling in different direction. the kinetic energies of both the bodies is equal (1/2*mv^2), because they have same speed and mass. now they collide each other. As they have same mass and speed they both stop. now the...
This is the barn pole paradox using a slightly curved pole and a silo instead of a perfectly straight pole and doors on a barn. Let's say we have a pole of proper length of 1 light-year that is traveling around a circle that has a curvature of 1 meter over 1 light-year of length. Let that pole...
i can't get my head around the twin paradox at all.
so twins A and B move relative to each other and as a result, according to special relativity, from twin A's perspective twin B will of aged less but from twin B's perspective twin A will of aged less. when they meet up which one will of...
I'm studying special relativity and I can't understand the following.
Let's imagine me and my twin brother making the following experiment: I stay in Earth and my brother travels in a spaceship with velocity 0.5c. For moving referentials the time passes more slowly, but for the first...
I guess the title gives it all. I understand the concept on a basic level. What i don't understand is that how does it "fit" in physics and astronomy. Any and all opinions are appreciated. Thank you :) .
i have encountered a problem with gravity, acording to logic gravity should not be able to work as it does in our universe or any other that has spatial dimensions that work in an identical way (even if said universe has less dimensions than our own). you are probobaly aware of a paradigm that...
Hello everyone.
My nine year old son and I were discussing the concept of the multiverse and he said this to me.
"I can disprove the theory of the multiverse"
"How?" I said
"We'll, if there exists at least one universe for every possibility then there must be a universe where there isn't...
Much of what people say about the vicinity of black holes doesn't seem to make sense.
For instance, it seems to be impossible for a black hole to grow by "ingestion" by scooping up matter around it or in its path, at least in the traditional sense. Gravitational time dilation takes care of...
I keep looking at these experiments that demonstrate violation of Bell's inequality and I really can't figure out why anyone cares. The scenario always seems wrong in some way.
For example the EPR paradox. The argument goes like this, if you start out with a source of entangled "photons"...
So once again, I'm trying to wrap my head around the asymmetry in the twin paradox problem. Here's my setup. The two twins start on a very massive but small planet such that they always have an unobstructed view of each other.
1. They each attach a beacon to themselves that will briefly flash...
Hi All,
I think that I understand (as far as you can!) the ideas behind explaining why two twins have different ages if one travels at near light speed away for a time and then returns to his twin on Earth (the return journey changing the inertial reference frame).
I have a related...
Hello
I have been doing some thinking related to Ampere law and behaviour of magnetic field inside materials of different permeability. In the process, I came up with the following thought experiment:
Try imagining a very long solenoid with steady current I. Turns of the solenoid are...
Say you have a particle in a one-dimensional box of length L.
The particle can only have momentum values of the form
p_{n} = \frac{nh}{2L} according to the De Broglie standing wave condition.
Now say I don't measure the position of the particle, but I know for certain that it is in the box...
What would be the example of the twin paradox where there is no acceleration at all ?
Only different periods of constant velocity for both twins. Or of periods with different velocities for both twins.
The black hole information paradox is resolved by considering that "...information is not lost in a black hole, but that all of the information of what is inside of a black hole can be viewed on the event horizon".
As the black hole gets smaller and smaller through the emission of Hawking...
Hi, I just recently studying special relativity in my class. It's fun and I kind of understand what's going on. But the professor skips the acceleration/deceleration part because it's for advance level. So what happens during the acceleration and deceleration (assuming the object won't get...