Time dilation Definition and 999 Threads

I would like to know why it is called time DILATION and not time CONTRACTION?

I'm sure the answer to this is obvious, but I'm at a loss. In the Hafele and Keating experiment where atomic clocks are flown east and west and compared to a stationary clock the eastbound clock lost 59 ns and the westbound clock gained 273 ns. My question is that if both eastbound and...

In SR, pure relative velocity between two observers causes a time dilation between them. It seems that if the two observers were at rest w.r.t. each other at some point in time, then the one who accelerates to achieve the relative velocity is the one who gets time dilation (i.e. comparatively...

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...

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...

Why is it that when describing time dilation, we say that the object (the thing observed) slows down relative to the subject (the observer), rather than vice versa? If the subject were to speed up, everything around them would appear slowed down, correct? Let me take a crack at this myself...

Homework Statement A spaceship approaches Earth with a speed of 0.6c. A passenger in the spaceship measures his heartbeat as 60 beats per minute. What is his heartbeat rate according to an observer who is rest relative to Earth? 1. 48 beats per minute 2. 56 beats per minute 3. 65 beats per...

Ok, so I just watched the nova fabric of the cosmos (blew my mind). Anyways, suppose I jumped on top of a beam of light and road it as it traveled out into space. Now, suppose that as I was traveling out there, another person is coming at me in the exact opposite direction on another beam of...

Time Dilation problem I understand Time Dilation and most of the principals involved. However I am still stuck on this one lingering question that I can’t make sense out of. If anyone could answer this I would really appreciate it. Given: 1. Person A is the traveler 2. Person B is...

Homework Statement Proxima Centauri, the star nearest our own, is some 4.2 ly away. (a) If a spaceship could travel at a speed of 0.24c, how long would it take to reach the star according to the spaceship's pilot? (b) What would someone in the frame that moves along with the spaceship...

I've been wondering.. If a person (A) is, say, on top of Mt. Everest, he would be moving faster than a guy (B) at the foot of the mountain since A is further from the center of the earth, but he would also be experiencing a weaker gravitational force than B. So, for which of the invidividuals...

I guess I have no problem with time dilation for stuff moving at less than c, but the step from less than to to c, is confusing me.

The distance to Alpha Centauri is 4,3 light years. How fast would a spaceship have to travel to get there in 10 years, according to the crew? The answer *should* be 0,395c. So far I've gotten all sorts of answers but not much close, so I seem to be approaching the problem the wrong way.

I've pondered a hypothetical problem Take as time perspective "A" as being relative time dilation of Earth Time dilation "B" being half of "A" slower due to relativistic effects. assuming both "A" and "B" were both formed at the same time say 5 billion years ago. If you were to...

If someone was to travel from the solar system to Proximi Centauri, I believe that from their point of view time would pass normally and regardless of how fast they were travelling, the speed of light would still be c. As I understand it, as the person traveling approaches c relative to Earth...

After i figured out how to show length contraction in this topic. I tried to use a similar way to show time dilation in Minkowski diagram. Time dilation means that time interval between two events is the shortest in the frame in which those two events happen in same place. We call this frame its...

I am trying to understand if SR can explain a real, measurable velocity time dilation as seen in experiments/observations like GPS satellite or Bailey et. al. Let us say we have twins sitting in their identical, individual spaceships in space, close to each other, and far away from any large...

As I understand it from what I have read the gravitational time dilation concept was arrived at through the equivalence principle. That the differential dilation at different locations in an accelerating system were derived from SR and included in GR by EP. But I have never encountered the...

Homework Statement At what speed relative to a laboratory does a clock tick at half the rate of an identical clock at rest in the laboratory. Give your answer as a fraction of c (speed of light) Homework Equations Δt=Δt'/√1-^2 The Attempt at a Solution My professor assigned this...

Does time dilation only affect matter that has mass? For example, A spaceship is 1 light year away from Earth at rest. It sent out a radio wave to Earth then travels at 99.99% of the speed of light. On Earth, from our perspective, we will receive that radio wave 1 year later but the spaceship...

Q1. Time Dilation Question Homework Statement Three identical triplets leave Earth when they reach the age of 21, in the year 2121. Each triplet goes on a spaceship journey that takes T years, as measured by a clock in each spaceship. During the journey they travel at a constant speed v, as...

1. Is there anyway we can measure time without depending on or using light? If we can, what are they and do special relativistic effects still take place in "close to c" relative velocity situations by using this method of time keeping? 2. My second question relates to relative movement. Time...

Hi, so I think I have a problem with how I am thinking about time dilation anyway here it is so if two events occur at the same position say light beam going up then back down and this occurs in frame S', this would be the proper time right? the interval between the two events. Now the...

I am sure this question is a lot more elementary than a lot of other posts on here - I am definitely a layman rather than a specialist, so I hope this isn't a problem. My hypothetical question is this: Person A is standing directly on earth, looking at his watch (so moving at the same speed...

Hi.. Speedo, flying in space, is at large speed compared to c relative to his brother on earth. Therefore, after a long time meeting at rest relative to each other, Speedo aged less than did his brother from his brother perspective. But from Speedo's point of view, his brother was also moving...

Firstly does a typical massed object surely prone to both kind of time dilations in its lifetime?? Consider 2 cases.. Firstly a person on a heavily massed planet where his time dilation is due to mass of that planet and in other case same person moving at c/2 away from any significant massed...

If you travel at a sufficiently fast speed, then according to relativity, you will age at a slower rate compared to your slower moving contemporaries. This implies that biological functions (say, of a person) and mechanical functions (say, of a machine) are literally functioning at a slower...

Hi, I am new to this forum, and I wish I get some help here. I really can't find any solution to this paradox; I am going to deny all the special theory of relativity because of this. The paradox is very simple, here it is: Consider two persons sitting on two adjacent trains at rest...

Hello When we try to find a formula for time dilation, we think of a situation where the velocity of the other frame is perpendicular to the velocity of the light (http://en.wikipedia.org/wiki/Time_dilation) Why is this? I know if we try any other direction there is length contraction...

Hi, I am having a hard time understanding one thing about this experiment for Time Dilation. I have one observer on a moving train measuring the time it takes for light to travel a distance d and be reflected back and one observer who is stationary, watching the same events. I understand the...

If I wanted to figure out the gravitational time dilation at different points in a the field around earth, could I just use v=gt. and find the speed that I would be moving if I went into free-fall from point x to point y. To figure out the time difference between x and y? and the t in v=gt...

Consider a massive object moving close to the speed of light. Imagine it travels close to a black hole, but does not enter the black hole. How do you calculate the exact time dilation experienced by the massive object's reference frame? How does time dilation due to movement stack with...

Imagine there is a train moving at .9c with a person on the train and an observer on a platform watching the train go by. The person on the train walks forward while shining a flashlight. To the observer on the platform, the person on the train is time dilated and walks forward in "slow...

Question: Why is the Bailey et. al. (1977) muon storage ring experiment not considered a refutation of GR, rather than being a corroboration of SR theory? It seems to establish that only velocity is the cause of time dilation, and the very high acceleration (order of 10^18g) plays no part in...

i just started studying special theory of relativity and am confused a lot. its first consequence,that is moving clocks run slow confuses me a lot. if two events happen then the time difference between them as measured by a clock in a frame moving at .9c would be lesser than the time measured by...

This is something that interested me after reading about time dilation. For the point of making it simpler, ignore relativity relating to gravitational fields Lets say for example, that the Earth does not orbit the sun, and the solar system doesn't orbit within the galaxy etc (makes it easier...

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...

I know that a black hole creates infinite curvature in spacetime and hence infinite time dilation. I was wondering though, if I could think of this stopping of time due to the fact that a light ray moving radially towards the centre of a black hole would have to travel infinitely far along the...

We all know that in general relativity, there is the idea that the gravitational force and accelerating reference frames are very closely related. In GR, gravity acts through distortions of the space-time continuum, which causes phenomena such as redshift and time dilation. My question is this...

Lets say I have 2 elevators And I have the same experiment in both. Now the first elevator goes into free fall in a constant gravitational field. Now a little bit later the second elevator goes into free fall. Now as the second elevator goes into free fall its wave function is the same as the...

New here, guys. I anterospectively appreciate your patience with me. I am neither a professional physicist nor even a student (at least not formally) of physics. However, after some perusing I just now understand the rudiments of special and, I think, general relativity. And, like a child...

My knowledge toward physics stay on high school level, and all i know about relativity are from wiki, so please make the explanation simple~ In wiki, it said it is possible and logical that B's time runs slower relative to A while A's time runs slower to B. But i still can't understand how...

I have a light clock onboard a spacecraft moving past the Earth parallel to an observer. The lightclock measures the time it takes for light waves to bounce between two mirriors. I have two sets of mirriors, one on the vertical axis perpendicular to the direction of travel and also a...

First post on PF! Anyways, I'm a high school student so please forgive my lack of knowledge in some areas :) So I was reading about special relativity and I understand the ideas behind both postulates. It's the application of those postulates that confuses me. For example, please let me...

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...

Ok I have attached a picture of what I am talking about. A, B, C, represent people with clocks. And A is at rest with respect to the middle of the planet. A, B , C all synchronize their clocks . Then B and C start to orbit around the planet with the same speed but in opposite directions...

Hi all. I'm having trouble getting an intuitive understanding for the following situation. Let frame A and frame B be moving with relative velocity v. It's true that a clock in frame A will be time dilated with respect to a clock in frame B, but also that a clock in frame B will be time...

Let's say I start out a few thousand kilometers from a black hole, and I begin to move toward the black hole due to it's gravitational pull. What type of time dilation would I experience as I fell into the black hole before the event horizon, and after the event horizon? By the time I die...

In the case where you have a photonic clock bouncing a photon between 2 mirrors, if the mirrors are alligned on the vertical axis, bouncing the photon up and down and the overall clock traveling along the horizontal axis, then the whole thing makes sense to me. However, if you were to rotate the...

If a simulated universe works on einstein relativity would the real world have ... ...To work on relativity? I think the maximum speed of the universe between real and simulated universe could vary but would time dilation still exist in both? And just for myself time dilation is when...