Simultaneity Definition and 298 Threads

let's say a train is traveling at relativistic speed along a straight line to right, and a man is standing in the middle of the train. Both end of the train was installed a gun which aims at the man. The right-ward gun aims at the man's leg and the left-ward gun aims at the man's head. In...

Ok so in Einstein's thought experiment with the train, everything makes sense except... Einstein is stating that an event doesn't happen until someone SEES it. But isn't there a difference between SEEING an event happen and the event happening regardless of whether someone sees it or not...

Homework Statement Spaceship with proper length 100m is moving at 0.2c in +x direction. In the back and front of the spaceship is a light source. a. When the light in the back is turned on, how long will it take for the light to reach the front of the spaceship? b. How about the light in...

Simple question, but I don't know exactly where to find the answer so I'll just ask. I'm just starting out learning SR, so I apologize if this is kind of trivial. If you have two inertial reference frames, and one is in motion relative to the other, I know it's possible for two events to be...

Please tell me if I have this correct. A particle has both a future light cone and a past light cone. In the past is everything that can affect the particle without exceeding Special Relativity. Now let’s say you have 2 entangled particles and you measure them so that each measurement is taken...

If I have a 1 light second long spacecraft with a clock at each end that are synchronised before take off, then I accelerate the craft to 0.5C. Are the clocks synchronised or is the leading clock 0.5 seconds ahead of the trailing clock?

In figure 3-1 (page 63) of Taylor and Wheeler's Spacetime Physics, the observer on the train determines that the lightning strikes are not simultaneous because the flashes do not reach her simultaneously. I see two problems with this. 1. The narrative in figure 3-1 contradicts the text in...

I'm sure someone else must have come up with this (the description in the third paragraph), but I haven't seen it. Briefly, for those not familiar with it, radar simultaneity generalizes Einstein's simultaneity convention directly to arbitrarility accelerating observer. Dalsepam has posted a...

Whenever you read about entangled particles, and how measuring one of them "immediately" changes the other, the problem of faster than light travel is usually dismissed with "o, but you can't use it to transmit information, so it doesn't contradict relativity". However, I think there's a more...

I had a much longer post typed with quotes and everything but I was auto-logged out, couldn't recover the text, and don't feel like typing it all in full. >:[ William Lane Craig, in "Einstein, Relativity, and Absolute Simultaneity" says that the Friedman metric as solution to Einstein's field...

Homework Statement The space and time coordinates for pairs of events are (ct,x,y)1 = (0.3,0.5,0.6) meters and (ct,x,y)2 = (0.4,0.7,0.9) meters. Could there be a causal connection between these two events? Is there a frame in which the two events would be recorded as simultaneous? If so...

Lets say that a person in a moving train throws a ball in the direction of motion from one end and hits the other end of the train at 10 mph (relative to the person on the train). According to special relativity, from the perspective of a platform observer though they would see the ball having...

I am interested in how the Lorentz maths were derived from the Maxwell electrodynamic and field equations. But not in a struct mathemetical sense as the math is outside my range but on a simpler conceptual level. For eg. contraction seems to have relevance wrt electron electrostatic fields and...

Homework Statement How fast must the observer be moving in the +x-axis direction so that events A and B occur simultaneously? Homework Equations I am currently in the solving stage of this problem and I need some help factoring this out/entering it into Octave. Can anyone help? The...

Homework Statement A train of 0.8 km (measured by an observer over the train) travels at a speed of 100 km/h. Two lightnings strike simultaneously the back and the front of the train, according to an observer on the ground. What is the time separating both strikes according to the observer on...

Homework Statement Homework Equations don't think need any equation The Attempt at a Solution a) i said that if the lightning is simultaneous in rocket frame, then the pilot is in the rockets frame there the rockets frame is the pilots frame therefore the pilot sees it...

Are accelerating lines of simultaneity correct?? This is an idea and question that I have been considering for a long time but put on hold while I sought a firmer grasp of the geometry of Minkowski spacetime graphs. My current understanding is this: Lines of simultanieity wrt inertial...

Homework Statement Homework Equations L=sqrt(1-(v/c)^2))*l t=T/sqrt(1-(v/c)^2) The Attempt at a Solution I'm having a hard time approaching this question. could someone tell me how to approach this question. NOT ASKING FOR ANSWER. never mid guys i got it. i forgot to read it happens in the...

I have recently attempted quantifying relativity of simultaneity and I was wondering if my attempt has been successful. Watch the below link before reading, as the calculations are based on the same type of event. As the video has no parameters, I have made my own. The velocity of...

Relativity says that there is no absolute simultaneity. Quantum mechanics with its entanglement seems to imply absolute simultaneity. And in between these two I am the one who gets confused. :smile: :confused: Please Help.

Hello all. This question is not specifically about the theory itself; but the way of explaining or interpreting it. I have found few explanations about theory of simultaneity which explain in the below mentioned fashion. My doubt is that - 1.1 Light speed is same in all the reference...

------------Frames and Lines of Simultaneity---------------- Is there any difference between the two? If there is what is it?? I may be missing something obvious but as far as I can see they are just two ways of graphing and conceptualizing a singular entity. Thanks

Iv been trying to get my head around the special theory of relativity and i think i may have found the particular part of the theory i do not understand; that being relativity of simultaneity. I was on a train recently, sitting about half way in the carriage, and i noticed two led clocks at...

In the double slit experiment, an observer appears to change the behavior of the particle/wave. Would it be possible to use relativistic simultaneity to explain the change in behavior of particles/waves? A potential passing by, and being observed by an observer, causes the potential to become...

Hi, A friend of mine asked me something about relativistic physics. It's all hypothetical and I told him it's a paradox that cannot be achieved since you cannot go back in time. Here's his assumption: Let's say that you pass through a 'wormhole' to a planet near Alpha Centauri (26...

Homework Statement A spaceship (SH) moves with speed v=0.6c relative to a space station (SS) (sic!). Two lasers, A and B, on the SS are 5.00m apart as measured by the SS observers. The gamma factor for a speed v=0.6c is 1.25. The lasers are fired simultaneously acc. to the SS observers...

There are two observers, A (stationary) and B (in the middle of a train moving towards A). At each end of the train is a lamp. At a point in time in the frame of reference of B, both lamps emit a pulse of light directed at B (middle of train). When the pulses hit B, they scatter in all...

if two events are simultaneous in an inertial frame, then they would not be simultaneous in another inertial frame as long as they are separated in space.Equally the vice versa is valid.Does this not imply that it would be possible for one to see someone to be born and to be dead at the same time?

I've been following Peter Lynds work- which is a periodic rediscovery of the philosophical difficulties surrounding the concept of discontinuity, threshold, edge etc and its application to Zeno's paradox. Lynds' solution has emerged a number of times in showing the paradox is invalid because...

Homework Statement An astronaut is space-traveling from planet X to planet Y at a speed of 0.17c. When he is precisely halfway between the planets, a distance of 1 light-hour from each, nuclear devices are detonated. The explosions are simultaneous in the astronaut's frame. What is the...

As Einstein pointed out, simultaneity is relative to the reference frame one is observing from. His classic train example describes two concurrent flashes of light viewed as simultaneous to a stationary observer half way between the two sources yet not viewed as simultaneous to an observer...

I was thinking about the Andromeda paradox and the following occurred to me. Any thoughts on whether this would be possible? I'm driving my car in a remote, non-light polluted location and ahead of me, just above the horizon. I see a very-distant star (a supernova). Just then, I see the...

The fact that the relativity of simultaneity causes events to not happen at the same time, dependent on reference frame, seems to imply a separate universe or world for each and every thing in the universe. Different events at different times due to the relativity of simultaneity would lead to...

Hello everybody, I know that there are a lot of questions about simultaneity, but mine is based on a specific aspect of it. In the book University physics ( with modern physics) they explain the train example and how the person inside of it sees the events happening non simultaneously...

Hi guys, I'm studying for a midterm and i decided to do some problems for practice and I'm stuck on a fairly simple one "The space and time coordinates of two events as measured in a frame S are as follows: Event 1 (x,0,0) @ t=x/c Event 2 (2x,0,0) @ t=x/2c There exists a frame in...

The train example discussing non-simultaneity that I'm sure most of you have heard of: However, wouldn't the passenger see the strikes of lightning at the same time? As she is in an inertial reference frame and is equi-distance from the front and back?

I was reviewing this concept last night, and it occurred to me that the statement Two spatially separated events simultaneous in one reference frame are not simultaneous in any other inertial frame moving relative to the first is not specific enough. If the simultaneous (as seen in S) events...

This is my first time posting so it's nice to meet everyone! I'm not trained in physics, but lately I've been very interested in and reading a lot about both Relativity and Quantum Mechanics. With regard to relativity, I found the topic of relativity of simultaneity very interesting. The...

I have recently been reading on the topic of the philosophy of relativity and the nature of spacetime. An interesting example of the difficulty of understanding the physical reality of the relativity of simultaneity has me very much at a loss to explain how the theory of relativity really...

My 9 year old son made an interesting observation, and I couldn't explain it. Maybe you can help. He interlocked several gears on his Lego set, all in a straight line. He then put a handle on the first one and turned it. Simple enough. Then he said to me, "Dad, when I move the first gear...

Ref:http://www.bartleby.com/173/9.html" I am having a little bother with this and hope that someone will be able to explain it for me:doh: If lightning strikes A & B simultaneously then, as those strikes are space-time 'events' they have no motion, only a time and a place. OK? Then, as...

Hi all, I am not a physicist. Some engineer friends of mine and I have a question about special relativity in two dimensions. To set it up, there are 2 lights floating in space parallel to the x-axis and a spaceship is traveling at .8c flying parallel to the y-axis towards the midpoint of...

Hi again, So I'm still relatively new to working with Relativity (no pun intended) and to these forums and I have a question about simultaneity. I have read that simultaneity is broken when events are viewed from different frames. I wasn't quite sure what this meant until I worked out an...

I came up with a sort of thought experiment to help me ask this question. It goes as such: Jack, Jill, and Joe sit near two buttons (Button A, and Button B). Joe sits directly in the middle of the two buttons, and is to push the buttons at the appropriate time. Jack and Jill sit on the left...

I got lost somewhere in this deduction that time is not simultaneous/equivalent for different reference frames. There are two points A and B that are distanced apart from each other along a railroad (the railroad will act as the reference body). Point M is the midpoint of segment AB. While...

I don't know if this is new or not but an alternative way of looking at simultenaity is 1. if you have two events 2. draw a straight line joining the two events 3 find the mid point of that line 4 draw a plane perpendicular to that line at the midpoint any number of observers moving in...

The following is the Einstein’s train but instead of train consider two airships of equal in lengths. http://www.youtube.com/watch?v=wteiuxyqtoM&feature=related Both are moving with same speed but opposite in direction. After certain time they cross each other such that one is exactly...

Hi, I'm studying special relativity this semester and stumbled onto a couple of problems. These have nothing to do with my homework or anything, they're just a couple of things I thought up. Since I have little contact with my teacher (it's an online course), it'd probably be a good idea to...

Hi, what do you think is the best and easiest way to describe the relativity of simultaneity? The best possibilities I'm aware of are: a) The one of Comstock (1910), who uses two platforms. On one platform we have the endpoints A and B, and from the middle between them a signal is sent to...

Hi, I've been reading some literature on Special Relativity, and even if I think I have more or less understood the relativity of simultaneity, some of its consequences (in the way I have understood it) appear too surprising to me. The problem is similar to the Andromeda Paradox, but seems even...