Contraction Definition and 689 Threads

Lets say we have an infinite charged wire with a line charge \lambda on it. Now when I move with respect to this wire the E field will increase do to length contraction. And there will also be a B field that we could calculate with ampere's law. But the increased E would make it seem...

Mach's principle is considered falls by many because mass anisotropy would not be consistent with the Huges-Drever experiments, which showed the isotropy of nuclear resonance. However, anisotropy appears as well in GR in the form of radial length contraction, which can be interpreted as increase...

Hi is this a correct contraction: R_{\mu \nu}=\eta^{\rho \alpha} \eta_{\alpha \sigma} R^{\sigma}_{\mu \nu \rho}

My understanding is that as I move, from my FoR all objects and space itself (according to Einstein) contract along the direction of my movement. This length contraction occurs for all space and objects in front of me for an infinite distance. Furthermore, relative motion is relative, and the...

I am confused about these two concupiscences of the consistency of light. One of my books/notes says that time dilation and length contraction do not happen at the same time because they are 'the same thing' which kind of makes sense but the other says "when we reach relativistic velocities both...

Unfortunately, my knowledge on this is limited to wiki which I trust is relatively correct but I would like to clear up some ambiguity. (I don't mind technical but please back it up with a general explanation since I am completely new to this. The general explanations I value more.) Wiki...

http://https://www.physicsforums.com/attachment.php?attachmentid=56297&stc=1&d=1362318192 problem:- The situation is shown in attachment. the right angled frame of rods (in stationary ) is moving at speed v perpendicular to its hypotenuse. according to length contraction the corresponding...

Special Relativity states that a ruler flying by at near the speed of light will appear to be shortened as observed by a stationary observer in the lab frame. This is, of course, exactly what happens to macroscopic objects. The question is how far can we push this into microscopic realm...

Hi I am struggling to see how the relation: (df:U)(dh:V)-(dh:V)(df:V) (1) can be rewritten as: U(fdh:v)-V(fdh:U)-fdh:[U,V] (2) I have tried expanding (1) out by making a scalar vector product of Udh:V but i don't think that is right and i am just not sure how best to proceed. It was...

according to special relativity theory, any object that has relative velocity also has lorenz- contraction L' = L0 *sqrt (1-(v/c^2)) it sounds odd that this is only kind of length contraction known to exist. why there are no other kind of length expansions or contractions, or are them...

Homework Statement Hey All; I am trying to follow along with the following example in my book, but I am getting lost somewhere. "We can perform another gedanken experiment to arrive at the same result (showing that length contraction is described as L=Lo/γ; this time we lay the meterstick...

f:[1,infinity)->[1,infinity) $f(x)=x^{0.5}+x^{-0.5}$ I thought about using MVT but it doesn't work and I've tried showing it conventially but i can't reduce it to k|x-y|

A body with a mass of 2 kg is released from rest a height of 0.4m above the edge of a vertical rested spring with k= 1960 N/m. Assume there is no energy loss in the collision: 1. what's the maximal contraction of the spring? 2. to what height will the body reach back? about 2 - Because I...

suppose I have a horizontal problem where I have a spring attached to a wall, a body that moves toward it in some inital speed and the surface isn't smooth so I have friction along the surface towards the spring and also while the body contracts the spring. I'm asked what's the maximal...

This is a very common topic especially regarding the apparent slowing down of time, the twins paradox etc. I have come across the figures for a muon and the relativistic effects that allow it to reach the Earth's surface despite its very short life. The relevant transforms show length...

Consider observer A at rest, seeing observer B traveling in a rocket at high speed towards a star C. Star C is at rest w.r.t. A. A in his frame sees B's rocket to be length contracted. B considers his distance to C to be shorter than (contracted) compared to what A sees. I seem to be...

Am I correct in thinking that the quantum mechanical de broglie wavelength explains relativity's contraction of matter? because lambda = h/p, as the velocity of say a proton increases, the momentum also increases, and the wavelength should get smaller because lim p-->infinity of h/p = 0. At very...

Double contraction of curvature tensor --> Ricci scalar times metric I'm trying to follow the derivation of the Einstein tensor through double contraction of the covariant derivative of the Bianchi identity. (Carroll presentation.) Only one step in this derivation still puzzles me. What I...

Hello, in my other topic members on the forum helped me to understand time dilation by using Minkowski spacetime diagram. Now i would also need some assistance with explaining length contraction in Minkowski spacetime diagram. I have observer Žiga in his frame ##x,ct## and observer Ranja...

I am on a spacecraft as it makes a journey between two planets. I use a lightpulse to measure the distance before I set off, I then accelerate to a speed that is close to the speed of light and measure the distance again. I find that the distance when I am stationary (relative to the planets)...

Hi, this isn't really a homework problem... but I'm just wondering I see the time axis as c*t, now people say that its to scale the time axis so that the world line of light is 45 degrees. But if you were to multiply time by the speed of light, wouldn't you just get the units metres or...

Here's a scenario: A rod shaped object 1m in diameter and 300m in length is moving through space at a velocity of .999994444429013c (picked that velocity arbitrarily for the 300:1 length contraction). The Lorentz factor is 300 for this problem. So the equation to figure length contraction is...

Hi Consider a spaceship at rest in space, this ship is equipped with a bomb connected to two rings. Once the rings connected to each other, the bomb explodes making the ship also explodes. The proper distance between the rings is one meter. Now consider a conducting rod of proper length one...

Inspired by Aziza's question i came up with a similar, seemingly puzzling question. Imagine a space-platform with a big cylinder on it. The cylinder has a hole drilled in, with a bomb-button at the end of the hole, which would trigger a bomb destroying the whole galaxy. A terrorist is on that...

Length Contraction "Ether wind" Homework Statement Due to the ether wind, anything that moves along it is "contracted". The Attempt at a Solution Taking L1 to be contracted length, (L1)2 = (L1x)2 + (L1Y)2 = (L10,X/γ)2 + (L10,Y)2But what they wrote is the opposite..

from wikipedia - "The Bohr radius is a physical constant, approximately equal to the most probable distance between the proton and electron in a hydrogen atom in its ground state." in Planck units bohr radius (a0) = (mp/me).(1/\alpha).(lp) the 1st 2 terms of the RHS of the equation are...

A spaceship with an arbitrarily large quantity of fuel cells departs Earth and accelerates away from it with a fixed trajectory until it reaches .9c. It continues to accelerate, but never reaches c because that is impossible for any object with mass. From the frame of reference of the crew...

Hi, I have a question that's been bugging me. For simplicity, assume everything is inertial. Let's say I take off in a spaceship from Earth towards a distant galaxy at .99999999C - so basically, the trip will be very fast, and let's say in one week time in my reference frame, it will appear...

If I am moving through space at a velocity that is a significant fraction of c, are all objects ahead of me in my path contracted in the direction of my travel for an infinite distance? In other words, are planets and stars from right in front of me to the edge of the known universe contracted...

Would it be possible for a truck, measuring 5ft tall when stationary, to pass under a 4ft barrier by accelerating towards the speed of light? If so what would a spectator see if standing next to the barrier, would the spectator see the truck shrink? What would you see of the barrier from the...

Hi, I have attempted the following questions but I am unsure of my answers/method. Could you guys please help me through? A super fast spacecraft is moving at a speed of 0.80c with respect to the observers on Earth. The spacecraft leaves Earth in May 2004 on its way to a distant solar...

U is the universal rest frame. A and B space ships pass U at t=0, moving at v. Both experience equal length contraction in the x direction. If length contraction is a result of em deformation in response to acceleration, then length expansion should be the response to deceleration. If the B...

Suppose you've just established the existence of time dilation using Einstein's 1905 postulates and the light clock. Is there any nice, easy way to go on and prove length contraction? Here are a couple of incorrect arguments that I've been guilty of using in the past: Symmetry: The Lorentz...

why does space time not contract uniformly in every direction around a fast moving object?

Homework Statement Two momentarily coincident observers approach a small and distant object. One measures the object to be twice as large as the other's measurement. Find their relative velocity. Homework Equations Lorentz Transforms L/L_0 = \sqrt(1 - \beta^2) The Attempt at...

Homework Statement A spaceship moves past you at speed v. You measure the ship to be 300 m long, whereas an astronaut on the ship measures a length of 356 m. Find v. Homework Equations L=L1sqrt(1-v^2/c^2) The Attempt at a Solution I have tried this by using the above formula. I...

Preparing for a classical prelim by going over previous exams. Homework Statement A relativistic meter stick moves with speed v in the lab. It collides head on with an impenetrable wall completely inelastically, thereby coming to rest in the lab frame. What is the maximum length of the stick...

In this thread in another forum, I calculated the coordinate speed of light as measured by a distant observer. As far as I understand it, the length contraction in GR is only in the radial direction, right? None tangent, correct? The time delay of light found, though, trying different examples...

If two clocks with observers attach to them move away from each with symmetrical acceleration, they will experience symmetrical time dilation, meaning they both see the rate of each other's clocks slow down relative to their own. However, if the acceleration is asymmetrical, the time dilation...

1: Does an observer, standing on the moon, see a brick, that is falling straight down, to contract? 2: Does an observer, standing on the moon, see a light pulse, that is falling straight down, to contract?

Homework Statement The picture shows the settings of the experiment.The aim of this experiment is to investigate about the expansion and contraction of gas. When the boiling tube is put into boiling water,the coloured water rises as air in the tube expands when heated When the boiling tube...

OK, I've found a great explanation of the derivation of the Lorentz transformation, with x' = γ [ x - v t ] t' = γ [ t - ( v / c2 ) x ] so if I take the other term as 0, there is x'( t = 0 ) = γ x t'( x = 0 ) = γ t but the problem is that the time dilation & length...

Homework Statement Two spaceships having rest length 100 m pass each other traveling opposite directions with a relative speed of 0.901 c As the front of the spaceships just cross, each pilot sets off a small flare at the back of her own ship, synchronized to the same instant (t=0 in her own...

Homework Statement Show that the length contraction deforms a sphere in motion to an oblate rotational ellipsoid whose volume decreases by a factor of γ (gamma) Homework Equations x=x'/γ v=4∏r^3/3 (volume for sphere) v=4∏(a^2)b/3 (volume for prolate and oblate spheroid) The...

hi sorry about my english. i am from france. i have a few questions about the image i have found in my schoolbook that i attached to this post. there is a light signal moving up and down and each time it reaches the upper mirror this is somehow detected. there are also two observers: one...

Can one detect length contraction due to general relativity? I.e does length/width/height change with distance to a gravitational centre? If so does the object get longer or shorter? I know this is the case with increasing speed in special relativity, but what about GR... If i went into...

An observer on Earth sees a meteor approaching rapidly, heading directly for the Earth's surface. At a certain instant, the Earth observer sees the meteor at 650m altitude. If the meteor is traveling at 0.92c, as recorded by an Earth radar, what would be the altitude as measured by the alien...

I have been wondering why the universe should behave in such a way. There is no obvious reason why gravity or speed should change the rate you travel through time or the relative distances, 1 second should be 1 second and 1 metre 1 metre whatever the strength of gravity or speed. The only...

Consider two observers in relative motion.At x'=0, t'=0, x=0, t=0. There's a box at distance x metres in the unprimed frame. Since the primed frame moves with a relative velocity v, he observes the length x to be contracted by a factor gamma. Does this imply that when the obsever in the unprimed...

Lets say I have 2 charged spheres that are connected by a spring and they are a distance d apart. The spring is made of a material that will not allow the charge to evenly distribute. And each sphere has the same charge q on it. Now I move with respect to this object and I should see the spring...