Paradox Definition and 1000 Threads

http://www.fas.harvard.edu/~scdiroff/lds/NewtonianMechanics/PascalsParadox/PascalsParadox002.gif the picture is from http://www.fas.harvard.edu/~scdiroff/lds/NewtonianMechanics/PascalsParadox/PascalsParadox.html The pressure on base of the first container (far left) and that of the second...

Ok for the record I havn't studied physics in a year, I'm a math student. But I was reminded of a paradox I came up with once in physics: Suppose we place a positively charged ball above an infinite plane with positive charge. We know by Gauss law that the electric force on the ball ends up...

Hi, I've seen many variations of explanations of the twin paradox using special relativity, but i haven't yet seen an explanation that bothers to take into account the initial acceleration of the traveling twin away from planet Earth. Is it safe to say that this can be neglected...

Now I know there's another thread like this, and I read through it but still don't understand... So I'll present my own 'case' here. Two astronauts pass each other in space at speeds close to that of light (let's say one is at rest while the other one has a velocity greater than zero). As...

so here is the problem The block in the figure below lies on a horizontal frictionless surface and is attached to the free end of the spring, with a spring constant of 40 N/m. Initially, the spring is at its relaxed length and the block is stationary at position x = 0. Then an applied force...

I was discussing the possibility of intergalactic travel with a friend and suddenly this occurred to me. Classically, if someone speeds away at the speed of light (or near to it), he returns without having aged as much as everyone else. But to him everything else sped away in the opposite...

Suppose we have time-dependent operator a(t) with the equal-time commutator [a(t),a^{\dag}(t)]=1 and in particular [a(0),a^{\dag}(0)]=1 with Hamiltonian H=\hbar \omega(a^\dag a+1/2) The Heisenberg equation of motion \frac{da}{dt}=\frac{i}{\hbar}[H,a]=-i\omega a implies...

If a spaceship housing humans were to travel near a black hole, time would slow down due to the increased gravity. However, with what we currently know about cellular biology and gravity, humans need to stay around 1g to proliferate properly. Now if the spaceship generates an artificial...

In my opinion the key to dealing with the current cosmological problems require applying some of the ancient spiritual Philosophies like buddhism. As I understand the big bang: Nothing can travel faster than light. Light travels at 2.998E^8m/s. The universe is accelerating at an increasing...

Just learned about it recently, and I'm curious to understand more. The 'mixing' form of the paradox goes something like this: Imagine a box partitioned in the middle. The two partitions are the same volume. In each there is a gas, on one side labelled A, and on the other B. The are held at...

I've read most of the Paradox within a Paradox thread but rather than hijack it to get to my point I thought I'd start a new thread. First, if this has already been addressed from this angle my apologies, but it is next to impossible to read through all the TP threads to try and find one from...

1) So let's say we have twin A and twin B. 2) Twin A stays on Earth. 3) Twin B goes on a trip nearly at the speed of light. 4) Twin A sees twin's B clock moving slower. 5) Twin B sees twin's A clock moving slower. 6) When twin B returns, twin A is older. #6 Implies that twin B's clock...

Homework Statement When Achiles decided to race with the tortoise, it had already walked 64 meters. After Achiles lowered the distance between him and the tortoise 8 times, he realized that he was 15 times faster than his opponent. Achiles stopped the race. How far did Achiles run before he...

So if you were to take the twin paradox, but make it so instead of the ship turning around and going to earth, the ship bends space through higher dimensions to return to Earth with no movement, what happens then? I'm sure this has been thought up of before, but i can't find an explanation that...

Hi. I am learning special Relativity and I am seeing that the answer to the twin paradox involves the Doppler effect, and I am struggling to understand what is going on. First let me explain what I know about the Doppler effect. If an object produces waves (might it be light waves or sound...

Consider A and B are moving in a linear motion, A claims B to move, and B claims that A is in motion, now when they look at each other they would clearly see which clock is running slower. Let us denote the resting object by x and the moving object by y. The special relativity explains, that...

Hi, I'm trying to prove D'alembert's paradox, but considering a nonviscous, irrotational flow of a fluid around a cylinder. I used the following webpage to help me, which was very good, but I got to a part where I can't seem to solve, perhaps cause my maths needs some brushing up...

Probably not but I'm too dumb to figure it out. I'll describe the scenario as clearly and concisely as I can: Suppose a space probe is sent out into space moving away from Earth at a relatively high velocity, but not high enough that there are any significant time dilation effects. Without...

Please excuse me if I seem inexperienced (I am new to this forum), but lately I've been thinking a lot about a length contraction paradox called the Barn-Pole Paradox. The paradox: A pole and a barn are both at rest relative to each other. When both are at rest, the pole is slightly longer...

Confused about this blueshift/redshift "paradox" Say you had a light probe with a sensor that converts light energy into electricity and and uses electricity generated to draft a chart of energy converted on paper. Now you send the probe on a 1 LY round trip. The probe has an internal drive...

The Grandfather Paradox Something that's been on my mind for sometime... If you were to travel back in time and kill your grandfather you would no longer exist...I believe this is false and What I'm saying is: If you travel back in time, you have removed yourself from your original...

The train paradox used to demonstrate relativity of simulatneity says that ( I will assume most people are familiar with it and therefore be brief) the observer on the train moves into the light from the front of the train and away from the light coming from the back of the train, therefore...

Homework Statement Hi! We have a parallel circuit on 230V, 60Hz voltage. One of the parallel's has a 0.0768H coil, the other has a 50 Ohm resistance on it. The question is: What is the effective I in the main current? Homework Equations Z = Lw The Attempt at a Solution OK, so I...

Friends, I will be happy if anybody throws light on the following concepts: (1). In the case of time dilation it is said that a clock in a moving frame appears to go slow to an observer in a resting frame.It leads to the famous twin paradox in which 'A' who spends some time in a spaceship...

When an ideal wheel rolls without slipping on a horizontal floor there is a frictional force exerted at the instantaneous point of contact between the wheel and the surface in the opposite direction to motion. But this frictional force does no work on the moving wheel because the point of...

Hi everyone I was in philosophy class today and my professor was going over what he said was a paradox with E=mc^2. He said that as defined energy is the ability to do work and that it does work on matter and in turn the work done on the matter creates energy in a cyclic process. The professor...

The cosmological principled as applied to modern cosmology and the standard model concerns only the spatial part of spacetime, this has been criticized based on Minkowski's predicated non-separability of spacetime, that led(among other things) to the "perfect cosmological principle" that...

Can we "use" the Andromeda Paradox? Perhaps the term I should be using is "relativity of simultaneity"... anyway :) Usually I see the Andromeda Paradox stated in terms of a stationary observer and another who is moving toward the galaxy. I did find one source that said the reverse effect...

we know that when the energy drops the entropy increases. but when the energy of a gas drops then it will become eventualy solid which has less degrees of freedem and therefore the entropy should decrease and not increase. Moreover high temp. has more entropy (gas for ex.) and as long as the...

I've read that the acceleration produced in the center of mass of a rigid body is equal to: AccelerationCenter of mass = Forceexternal / Mass However, that leads to a counter-intuitive conclusion. The reason that seems unintuitive to me is that I would expect some rotation to happen...

Here is a thought experiment to illustrate the problem... Suppose you have a light source capable of emitting single photons on command from a computer. these photons travel through a barrier with two parallel slits and then strike a charge coupled device. The computer records each strike and...

A warm up problem 1 Somebody flips two coins on table, and then hides them with some two pieces of clothing. You observe, when one of the coins is revealed, and it is heads or tails. You are then asked to guess what's the side of the unrevealed coin. Which ever answer you give, you are right...

Here comes the model situation. I have a man on a planet and two ships. One ship will go straight to from a planet and another one will go opposite direction. Well that's for me very interesting. Because i will travel with ship near to speed of light from Earth the Earth time will be for me...

I have read many arguments concerning the issue of the famed “Twin Clock Paradox”. Very many arguments go through considerably complex explanations so as to defend Special Relativity or dispute it. But the explanation is actually much simpler. In every proposed twins paradox, there is a Frame...

I discovered a mathamatical truth that seems to have no clear logical foundation. Could anyone here explain the math behind the following? A.Given the following recursive series: S(1) = 3 S(2) = 2 S(n) = 6*S(n-1) - S(n-2) - 4 Define a new series as follows N(i) = (S(i) + S(i+1) +...

You have a weightless rod with a wheel attached to one end (weightless, frictionless) and a weight attached to the other. The weight is mounted on a short axle, and can rotate freely. With the wheel on the floor, the rod is held at 45 degrees to the horizontal and then released. Since the rod...

The title is the best way I could group this thought. And the following is most likely sloppy so I do apologize. I get the 'feeling' (subjective I know), that the measurement effecting the outcome i.e. only being able to measure position over velocity, collapsing wave functions, etc... comes...

Just an amateur (and hardly even that)... so take it easy on me... but I have some questions about the Grandfather Paradox. Assuming time travel to your past were otherwise possible, doesn't that imply that each moment in time is its own unique physical state existing simultaneously...

I'll first derive here the gravitational pot. energy by my method, and then I'll give the method that has been formally used in books. My answer differs from the actual one by a minus sign. My derivation: Let mass M be at the origin O. Let another mass m be at an arbitrary position r from...

This relates to another thread about trains and manhole covers at relativistic speeds falling (or not) down gaps that would be normally be too small. Consider two hollow cylinders aligned with each other along their long axes with a short gap between the hollow cylinders. They are designed...

Hi We've just begun studying magnetic force in school. Our teacher told us to explore the possibility of a paradoxical situation as F=qBv From different inertial frames, the apparent force will be different, won't it ? Our teacher told us that Einstein's theory of relativity solved the...

In this hypothetical, an experiment is going to be conducted concerning the repositioning of clocks. two clocks are placed at the leading end of a vessel, that is 1 light second long, to an observer at rest relative to it. This vessel is shot into space from an observation station at...

This is a paradox that I have derived based on my understanding of relativity of simultaneity. Upon someone resolving it, I should be better able to understand the concept, which seems rather contradictory of the greater theory at this point in time. If events are considered to be...

We're all too familiar with the version of the Omnipotence paradox, the so-called paradox of the stone : Can God create a rock so heavy that even he cannot lift it? ... (1) ... which has been discussed ad nauseam in philosophy classes and on the web. Now, how about this version: Can...

A friend of mine posed this SR paradox to me a few weeks ago and I was unable to come up with a convincing answer (nor have I been convinced by any I've heard!). The problem is as follows: Assume we have a train track which has certain gaps in it. At rest, the train which moves on the track is...

First of all, hello forum. I'm new. :biggrin: Alright, so I was recently informed of two things. I'm no physics student, but nonetheless I was still interested in these things. 1. The speed of light is always constant for all observers. 2. To compensate for the paradox of a light particle...

In four dimensions, a flat torus is an object that has zero curvature but still has closed geodesic curves. What this means is that if you try to measure geometry locally, you will find that it is perfectly Euclidean. Nevertheless, if you travel on a straight line, you'll eventually end up...

Why do we call them 3 dimensions when all that they are, are just the ability of movement in space? Physical movement cannot be restrained in any vector. It takes place in a 3 dimensional dimension. Thus 1 dimension is physical movement in space and the second dimension is time. Within the 1st...

I was just working on my knowledge of the twin paradox, and had a question that I couldn't find an answer to anywhere: If I understand it correctly the paradox is resolved because the two frames are not symmetrical, one is non-inertial, so that frame has it's clock run slower. So if you carry...

1. Homework Statement Suppose that in sherwood forest, the average radius of a tree is equal to R= 1m and the average number of trees per unit area sigma = 0.005 m^-2 . If Robin Hood shoots an arrow in a random direction , how far , on average, will it travel before it strikes a tree? 2...