Simultaneity Definition and 298 Threads

Hello PF. There are two lightning flashes , and two stationary observers. Observer 1 who is equidistant from the flashes, sees them as simultaneous Observer 2 stands one step to the side of observer 1, and is not equidistant. He sees the flashes as separate, the light having unequal distances...

As I understand, one of the Special Relativity roots is the statement that two events SIMULTANEOUS in one inertial frame are NOT necessarily simultaneous in another inertial frame that is moving against the first one. To illustrate and PROVE this statement Einstein gave his well known example...

A field is defined as a distribution throughout all space (or at least a portion of it). But all of (a portion of) space means all of space at a particular moment, no? But that sounds as if it assumes simultaneity. But I thought simultaneity was a meaningless concept, according to relativity...

Hey everyone, I have this doubt for quite some time now. So could somebody please help me and explain where I am going wrong with this. According to the relativity of simultaneity, it is impossible to say in an absolute sense whether two distinct events occur at the same time if those events...

Dear PF Forum, What does "at the same time" mean for two observers? I've read https://www.physicsforums.com/threads/criteria-of-simultaneity.699560/. But I want to ask a simpler question. 1. Does "At the same time" mean different for two COMOVING observers than two REST observers? And about this...

Good morning, Yesterday I was reading a book about special relativity, It focused a lot about consequences of the theory, but there's only one thing I couldn't understand, which is as the title suggests, Relativity of simultaneity, that two different observers can't agree if two event are...

Hi, This is not a question aimed at answering a homework problem, but since it is part of a course on Special Relativity, I believe I'm supposed to put my question here. The course itself, however, is a Dutch High School syllabus on SR, so I won't be able to link to source material. The...

I addressed already recently in this thread the issue of defining the synchronicity of clocks moving relatively to each other (considering that the synchronization by Einstein's method implies clocks at rest), but it occurred to me now that even for clocks at rest relatively to each other there...

This is something I've been meaning to write for a while, I finally got the time to do it, though the topic isn't currently "hot". I'm sure it will pop up again, though. Imagine we have two observers, moving at a constant velocity relative to each other far away from any objects that might...

In SR, we may choose any inertial observer and his reference frame at which he is at rest, and other observers are movin wrt to him. All the moving observers 'slice' spacetime in a different way than the observer at rest, at different angles relative to his simultaneity surfaces. This is all...

If relative simultaneity implies that one event that could be already measured w.r.t. one reference frame not yet measured w.r.t. another reference frame: then could one find an reference frame at which none of the events were measured? If such reference frame exists, could one observe the...

So, I think most of the folks here are familiar with Einstein's thought experiment that illustrates the relativity of simultaneity by using two lightning bolts and how the light reaches an observer on a moving train; that an observer on the ground observers the strikes simultaneously, but an...

Please take this post with a grain of salt as I am a computer scientist and not a mathematician or physicist. I started in on Einstein's Relativity: The Special and The General, and just finished the section on the train thought experiment involving simultaneity. I then started in on the...

The position of the rocket is not specific. We just know that it is at the left of the galaxy. We know that R will explode first in the rocket's frame. Maybe the galaxy could be moving fast enough so that the time it takes for L to explode is enough for the rocket to see R's light first. In...

according to the relativity of simultaneity, when two people are at opposite ends of a moving train, and in their reference frame sign a paper at the same time when a beam of light emitted from the center of the train reaches them, observers on the outside of the train will say that the person...

"I've looked this up and came up to similar questions but haven't seen it been explained very clear yet. Excuse me if such questions were already posted here. There are two different kinds of simultaneity it seems to me:Let's take the event of two lightning bolts striking earth. Observer A is...

Homework Statement An experimenter triggers two lights simultaneously, which produces a large flash located at the origin of his reference frame and a small one at x = 23.8 km. An observer, who moves with speed 0.374c in the positive x direction, also views the flashes. What is the time...

I also have a question about the Relativity of Simultaneity ( S&G part 1 sec. 9 ). In Einstein's thought experiment lightning strikes the tracks at each end of a train. The embankment observer who is equidistant from the strikes sees them as simultaneous. The onboard ( moving ) train observer...

1. Two events occur simultaneously in an inertial reference frame, separated by a distance of 3 metres. Within a different inertial frame that is moving with respect to the first, one event occurs 10^-8 seconds later than the other. (a) In the moving frame, what is the spatial distance between...

I have been studying special relativity and in working with Minkowski diagrams I have come to wonder if when simultaneity is shifted based on relative movement, does this 'shiftting' of simultaneity happen instantaneously across all of space? When a reference frame moves relative to something...

A interesting question came up to my mind, and it's related to the concept of different synchonization methods. If we change the synchronization parameter from 1/2 to some other value, light will have different velocities in opposite directions, which implies that two velocities with opposite...

Hi guys, I was thinking about the relativistic effects a little bit, and I have a question regarding relative simultaneity. Time dilation and length contraction grow as a function of the speed of the observer, and become noticeable and large on speeds close to the speed of light. By this...

One problem in understanding Special Relativity is that it is intuitively hard to agree with relative simultaneity. My major problem is that I cannot quite answer the question: Is relative simultaneity a real effect or only a mathematical artifact of Lorentz transformation? I am not...

Instantaneous action-at-a-distance (which is how we explain quantum entanglement) implies event-simultaneity, but we know (from SR) that an observer's "now" is dependent upon their velocity/reference frame. Imagine that we have two observers, Scott and Sean, and two entangled particles. Scott...

The three main effects of SR occur in inertial frames and change the description of space-time relative to a particular observer. My question here is how do these effects occur on Earth, since we know that motion on Earth is non-inertial. I know that we travel at small speeds and that we can't...

Hi guys, I'm reading a text regarding different possible ways of synchronizing clocks in an inertial frame, so maybe somebody could help me with some details. The standard ways, the Einstein synchronisation, is characterized by the synchronisation parameter which is 1/2. Since I've red that...

I am having a hard time understanding a scenario that I have not found discussed elsewhere. It has to do with simultaneity and information content. There are two digital clocks on either end of a spaceship. Clock L on the left, Clock R on the right. They have digital displays, showing time...

We have had a number of threads on how to synchronise clocks around a rotating ring. One method of doing this is to start all the clocks on the ring via a signal from the centre of the ring. This method has the advantage of being transitive, but has the disadvantage that the local one-way speed...

Hey guys based on the Einstein train thought experiment we can say that different inertial frames disagree on simultaneity. In that specific example, the train observer is moving towards one thunder, and away from the second and in his frame the thunder in front of him occurs first followed...

Why do we always need to define simultaneity in relativity. The moving train with a light signal at the mid point reaches the engine and caboose at the same time and gives us a way to define simultaneity. But what is it's purpose. if G = gamma = 1/ ( [ 1-V*V/C*C ] ) ^1/2 And from...

Imagine a 2.3 Ly long box. At the middle of the box there's a half silvered mirror (S) which splits laser beam into two and reflects to the both end of the box which is also mirrors that are facing each other (mirror A & B). Another observer (O) is placed 1.15 Ly away from mirror A in a series...

Thanks for the answers on my previous thread, it made some sense, and if I'll reply if there's further misconception. My new question is quite connected to the famous Andromeda paradox. So it's stated that the Andromeda is far away and moving towards the galaxy will cause the observer to have...

"Global simultaneity surfaces" For a long time I had basically taken for granted the usual interpretation of one-parameter families of orthogonal space-like hypersurfaces relativized to a time-like congruence as "global simultaneity surfaces" (c.f. MTW section 27.3), and left it at that. See...

Homework Statement Two objects, Red and Blue, are in inertial motion with respect to each other and are graphed on the attached Minkowski diagram (representing a third inertial frame). Red and Blue are in relative motion along the x axis, and offset slightly on the z axis such that they...

Hi, I've been trying to understand the (lack of) simultaneity between events in reference frames moving wrt each other. I'd be grateful if someone could confirm that I've got things right: If two events are simultaneous in one reference frame (S'), then they will not be simultaneous in a...

Hi, I have been pondering a special relativity question about the concept of simultaneity when moving at speed of light. Say for instance I took a round trip to Alpha Centauri 4 light years away, traveling at the speed of light both out and home (using negligible time to turn around). Then...

Recently i found a problem with relativity of simultaneity, its a paradox within relativity of simultaneity. It is probably unexplainable and i would like to publish it without losing my credit. Can anybody tell me any way to publish it? I'm not rich to spend money, but is there any simple way...

Hi, Consider an observer S pushing a fork towards a material x-axis as seen in the figure below According to this observer E and F cut x-axis simultaneously. Now consider an observer S' moving along x-axis with a constant relativistic speed. It is very easy, using Lorentz transformation, to...

Hi guys, I thought lot about this and I need an opinion from people who will be able to give me an appropriate answer that may serve me well. My question is about the consequences of Lorentz transformations. So I hope you'll be able to correct if I'm wrong in some sentences and add what's been...

I’ve been trying to get my brain around Einstein’s theory of special relativity, and I find I'm a bit perplexed about his thought experiment (TE) involving the speeding train and the two simultaneous lightning strikes. To briefly summarize, observer M is standing on a stationary “embankment”...

Heys guys, I asked a similar question in one of the previous threads and therefore I apologize if anybody is offended or thinks I'm asking too much. I just want to clear and define some concepts in my head. So it is agreed that simultaneity is a convention and that in SR inertial frames...

i'm reading over the GRE prep book and i just got to the question: "System S' travels with constant velocity v≠0 w.r.t. system S. If two events, separated by a distance x≠0, occur simultaneously at time t in S, do they occur simultaneously in S'?" the answer is "No, never". But the "never"...

It's a pretty straight-forward question, and it got me confused since most articles on the internet mention planes of simultaneity in the context of inertial frames. So if rotating frames also have planes of simultaneity, what SR says about it and how does it differ from the planes of...

Hi guys, I've recently started studying relativity and I thought I was on a good path but I got a little confused with some concepts. I've red a lot about the Andromeda paradox, the train and tunnel experiment and so on so I'll present my question in a way related to those topics. In my...

Hi, I'm not a physicist, I'm 32 years old and I like physics. For the past years I've been troubled by an issue: the known thought experiment of Einstein with the train and the relativity of simultaneity notion. Now, most probably I'm wrong or I'm missing something but I think that there is a...

Hi, this question may sound similar to the one I asked about a month ago, but I will give my shot to explain what's been bothering me. In almost all interpretations of the special relativity, it is stated that two events that are simultaneous in one reference frame are not in another. And that's...

This question may be kind of metaphysical, but I don't understand the relativity of simultaneity and its implications. If the temporal order of two distant events varies depending on the reference frame, are the parts of the event (or a temporal object) simultaneous with it in all frames of...

So I've been doing some review on special relativity and I realized that I never fully understood how simultaneity is relative in special relativity. Taking the thought experiment about a lightbulb being turned on in a train, I get that the observer in the middle of the train will see light...

Homework Statement To an observer in frame S, two events are simultaneous and occur 600km apart. What is the time measured by an observer in frame S' who measures their spatial separation to be 1200km? Explain the sign of your answer. Homework Equations Lorentz Transformation t' =...

Still confusion in relativity of simultaneity and time dilation... Hello friend, Still Something in my mind is saying that Relativity of simultaneity is the reason for time dilation even though i had some corrections in my understanding by posting various threads. Well,let me use Einstein's...