Contraction Definition and 689 Threads

Since special relativity insists that length is not invariant but rather depends on the frame of reference from which an object or distance is observed... and since the cosmos is many billions of years older than any possible observer, then objects and the distances between them must exist...

Homework Statement why the formula of fricitional pipe loss due to contraction is given by formula : kc(V^2)/2g ? why the formula of fricitional pipe loss due to contraction can't be formula : (Va^2)-(Vb^2)/2g ? ,where Va= velocity at inlet , Vb = velocity at outlet ? Homework EquationsThe...

Hey guys, In what circumstance or scenario would you use Lorentz transformations as a opposed to time dilation or length contraction? The reason that I ask this is because in all of the problems that I have worked with, the observer is always stationary relative to the event. For example, if...

Homework Statement what does the author mean by D2/ D1 = 0 ? when D2/ D1 = 0 , the pipe doesn't exist , right ? Homework EquationsThe Attempt at a Solution

When I first learned special relativity it was on an elementary level. I was told that "space itself" contracts in a moving reference frame. Now I am studying electrodynamics out of Griffiths. I just read the derivation of the Lienard-Wiechert potential and the fields for a moving charge...

Homework Statement We can make a rough estimate of how much the envelope of a red giant should expand as a result of the contraction of its core based on conservation of energy. We will consider a star of mass M and initial radius R, with a core of mass Mc and radius Rc. We will focus on the...

I read that: "Length contraction is caused because moving objects bend space. And that is the difference between Lorentz's and Einstein's length contraction concepts. Lorentz thought length contraction really occurs but Einstein thought that length contraction is a consequence of bending space...

I have a very basic question about the relativity of simultaneity (damn that's a mouth full). So basically rule no. 1 would be that it's all relative right? In the example of the ladder thought experiment it's shown that because of "Lorentz length contraction" a ladder which is bigger than a...

(Sorry my bad English). I'd like to know if a body traveling near the speed of light really experiences a length contraction or if it SEEMS to be contracted for an observer in a inertial frame.

Hi, I was wondering if there exists some software to find the following contraction in an easy way $$M_{ad}M^{be}M^{cf} f^d_{bc}f^a_{ef}$$ Here the 4x4 metric M has a block diagonal form $$ \begin{pmatrix} e^\phi & 0\\ 0 & e^{-\phi/3}N \end{pmatrix}$$ With ##N## a symmetric 3x3 matrix of...

I was reading about (The train-and-platform thought experiment) from https://en.wikipedia.org/wiki/Relativity_of_simultaneity and was wondering a couple of things. 1.) Would the observer on the train agree with the stationary observer that event A and B happen at the same place in the stationary...

Homework Statement After year of over-eating and no exercise, Uncle Joe's is overweight, with a waist 50cm wide. He's also out of shape and can only hold his breath for 20 seconds. Worse, he can only jump 20cm high. But at his high-school reunion, he'd like to fool his old friends who haven;t...

Lorentz contraction problem: By Bertrand Boucquillon Components of the problem: - Bob (observer) - 2 identical rods that both measure 1 meter. Let's call them rod X and rod Y - Point A - Point B Scenario (step by step): 1) Bob is at point A, and is at rest with both rods in his hands 2) Bob...

Homework Statement You are watching a race between two space ships who pass you moving at different constant speeds. In your reference frame, both ships are the same length while moving. It takes the first ship 26.8 minutes to get to the finish line a distance 14 light-minutes away. It takes...

Hello, from time to time I got question in physics for which I can't readily find answers. I hope I can get answers here. Here is my current one: Usually textbooks state that space contracts in direction parallel to direction of motion. It sounds strange, because time changes uniformly, and as I...

Hey, I'm currently working on an explanation of the special Relativity. Now I'm at the point of explaining length contraction, but I don't understand why the following example is a reason for length contraction to exist: Imagine we have two Lightclocks in a fast moving Rocket. Lightclock 1...

I have been trying for hours to understand what is physically causing the interferometric rings to contract when the separation of the mirrors is reduced. From the equation: m\lambda = 2Lcos\theta, where m is the number of fringes, if we consider just one fringe at a fixed wavelength...

I was looking at the barn door paradox, http://math.ucr.edu/home/baez/physics/Relativity/SR/barn_pole.html But supposing that instead of a barn, there was a piece of measuring apparatus which was in two halves, with a gap in between through which the pole would pass. One half of the measuring...

Could any of the experts here say whether there could be a clue here as to how to resolve the apparent paradoxes of quantum entanglement? I mean if a distance is reduced to zero, in a photon' s frame, then we should not be surprised that measurements made on one of a pair should be reflected...

Since galaxies are moving away from us, shouldn't they be contracted in length than they would be if they were at rest (wrt us)? In other words, are we observing increasingly shrunken galaxies as we look deeper into space? When measuring supernova light curves, we do adjust for time dilation...

Homework Statement A Train is driving with a uniformed velocity. v=1/4 c. The train is driving under a bridge, which is rotated \theta=30 degree in relation to the railway. The bridges length is 20 m long in a reference frame of the bridge (stationary bridge). Calculate the length of the...

Homework Statement The highest energy protons have gamma factors around ##1.0*10^{12}##. (a) Our galaxy has a disk diameter of 30 kpc, which is ##9.3*10^{20}m##. If a photon and one of these high energy protons start traversing the galaxy at the same time, by how long will the arrival of the...

Homework Statement can somebody help my figure out what t0 l0 l and t is? For instance: A girl an her dad are in an airplane, the girl starts running 20m in 8 seconds. There is also a boy standing beneath the plane (lets pretend that the airplanes floor is seethrough. Homework EquationsThe...

Considering the enormous number of questions posed on this forum and other places, the concepts seem fundamentally flawed (because both are formally and practically unobservable). The calculations themselves (together with the Lorentz Transform) are highly error-prone and the results misleading...

First, let me clarify if my understanding of length contraction is correct. Is it accurate to say that relativistic velocities not only affect the measured length of an object in the direction of motion, but also the distance to the object from an observer in the direction of motion? For...

traveling at the ~speed of light leads to length contraction. based on that wouldn't a 20AU path be shorter if traveled at speeds near the speed of light ?

A number of contemporary models propose that the universe was contracting prior to expansion. However I have found this critique of such a proposal from Geroge Elliss: “initial conditions have to be set in an extremely special way at the start of the collapse phase … in an acausal way (in the...

bcrowell wrote: "Lorentz contraction doesn't describe what we see. When we see things, that's an optical measurement. Relativistic optics is a whole separate subject. Lorentz contraction describes the results of the kind of elaborate surveying process that we have to undertake in order to lay...

A highly accelerated object near the speed of light,should be seen contracting faster,than the speed of light.Maybe the contraction could not be observed?

Reading an old thread (wich is now closed or i would post the question there) there was a discussion about the size of a photon, and if it was an adequate question at all. The discussion on the other thread couldn't agree on a response. Yet there was some postulates that could work with this...

1,2,3. Homework Statement I tried to derive the length contraction using the Lorentz transformation matrix and considering 2 events. I reached the correct result but there's a step that I had to assume that I don't understand. Consider a ruler of length L along the x-axis for an observer at...

Let (X, d) be a complete metric space, and suppose T : X → X is a function such that T^2 is a contraction. [By T^2, we mean the function T^2 : X → X given by T^2(x) = T(T(x))]. Show that T has a unique fixed point in X. So I have an answer, but I am not sure whether it is correct. It goes as...

Let $X=[1,\infty)$ and $T:X\to X$. Define $T=x+\frac{1}{x}$...Please show that T is not a contraction

Big bounce cosmic models, as a research topic, shouldn't be confused with cyclic models where there is a recurrent bounce. The earlier thread by mykamakiri got a bit distracted because of that kind of confusion so I thought I would split off a separate topic just to focus on the question in the...

Let $\left(X,d\right)$ be a complete metric space and suppose that $f:X\to X$ satisfies $d\left(fx,fy\right)\le\beta\left(d\left(x,y\right)\right)d\left(x,y\right)$ for all x,y $\in$ X where $\beta$ is a decreasing function on ${R}^{+}$ to $[0,1)$. Then $f$ has a unique fixed point. The...

İn some fixed point theory books, I saw an expression...But I didnt understand what this mean...Please can you help me ? " It was important in the proof of banach contraction principle that the contraction constant "h" be strictly less than 1. Than gave us control over the rate of convergence...

Please can you prove that $f\left(x\right)={e}^{{-e}^{-x}}$ is contraction mapping on R...Thank you for your attention...

So i was watching this video : And it got me thinking... i began wondering why, when space contracts from someones frame of reference (In the video, this would be the frame of reference of the cat), why is it that the protons don't become black-holes when the space contracts? If the density...

Say you have a scalar ##S=A^{\alpha}_{\beta}B^{\beta}_{\alpha}## . Since this just means to sum over ##{\alpha}## and ##{\beta}## , is it allowable to rewrite it as ##S=A^{\alpha}_{\alpha}B^{\beta}_{\beta}## . I don't see anything wrong with this, I simply rewrote the dummy indices, but since I...

It was important in the proof of BCP that the contraction constant h be strictly less than 1. That gave us control over the rate of convergence of f^n (x0) to the fixed point since h^n goes to 0 as n goes to infinity...If we consider f is contractive mapping instead of a contraction, then we...

Just wondering if someone could check that I am understating this aspect of length contraction correctly... I am in a spaceship moving at say a speed of 0.6c relative to some imaginary ruler in space which has increments set 1 meter apart. (1 meter in the ruler's rest frame.) I am moving along...

Let $(X,d)$ be a complete metric space, and suppose that $f:X \to X$ satisfies the condition: for each $\epsilon >0$, there exists $\delta > 0$ such that for all $x,y \in X$ $$ \epsilon \le d(x,y) < \epsilon+\delta \implies d(f(x),f(y)) < \epsilon.$$Clearly, this condition...

I have been coding a speed of light simulator and I am having a bit of trouble with a few aspects of the project. My first question is: Are the length contraction and relativistic aberration formulas BOTH needed in my calculations or does the relativistic aberration formula already account for...

Please see the picture. Red dots are stars, lines are the path that light takes, our observer is at center. Assuming that stars are somewhat uniformly spread around us, I suppose that stationary observer (left picture) sees about as many stars in every direction, but an observer moving in...

If a frame is moving at constant velocity relative to an observer, this observer perceives a time dilation and a length contraction. But in this case how the velocity (length/time) can appear constant ? It is expected to be contracted.. Thank you in advance for the explanation

I hope to lay to rest two of the misconceptions about special relativity that are evident in the many questions asked here. 1) Why is the speed of light a constant ? Everybody believes Pythagoras's theorem that the length of the hypotenuse of a right angle triangle is ##\sqrt{s_1^2+s_2^2}##...

Hi all, I want to make sure of a particular information. Length is contracted only in direction of motion. If I am on a spacecraft moving with high speed, I shall see the universe is contracted just in front of me that I am going to, but there would be no contraction If I look to regions that...

Suppose I have something like \left( \nabla_\mu \nabla_\beta - \nabla_\beta \nabla_\mu \right) V^\mu = R_{\nu \beta} V^\nu Can since all the terms involving ##\mu## on the left and ##\nu## on the right are contractions, can I simply do: \left( \nabla^\mu \nabla_\beta - \nabla_\beta \nabla^\mu...

Dear PF Forum I want to know about these questions that are still bothering me, Does the universe have preferred frame of refference? Why there's twins paradox? Motion is relative, why 1 clock experiences time dilation while the other doesn't? V = \sqrt\frac{3}{4} ≈ 86.6\% If V define ratio of...

Muon created by fast cosmic ray has speed 2.99X10^8 m/s and life time 2.2 micro sec. According to this numbers muon should travel only 0.66Km with respect to Earth in his life time. however it travels more than 10 km (10.4km) due to time dilation. in muon frame of reference, Earth travels only...