What is Simultaneity: Definition and 297 Discussions

In music, a simultaneity is more than one complete musical texture occurring at the same time, rather than in succession. This first appeared in the music of Charles Ives, and is common in the music of Conlon Nancarrow and others.
In music theory, a pitch simultaneity is more than one pitch or pitch class all of which occur at the same time, or simultaneously: "A set of notes sounded together." Simultaneity is a more specific and more general term than chord: many but not all chords or harmonies are simultaneities, though not all but some simultaneities are chords. For example, arpeggios are chords whose tones are not simultaneous. "The practice of harmony typically involves both simultaneity...and linearity."A simultaneity succession is a series of different groups of pitches or pitch classes, each of which is played at the same time as the other pitches of its group. Thus, a simultaneity succession is a succession of simultaneities.
Similarly, simultaneity succession is a more general term than chord progression or harmonic progression: most chord progressions or harmonic progressions are then simultaneity successions, though not all simultaneity successions are harmonic progressions and not all simultaneities are chords.

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  1. R

    Doubt in Relativity of Simultaneity

    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...
  2. Stephanus

    Simultaneity of Events: Understanding Observer Perspectives on Time

    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...
  3. Noctisdark

    Understanding the Relativity of Simultaneity in Special Relativity

    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...
  4. H

    Problem Perceiving Simultaneity (Special Relativity)

    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...
  5. F

    Clock synchronization and relativity of simultaneity

    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...
  6. P

    Symmetrical time dilation implies relativity of simultaneity

    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...
  7. S

    SR vs GR Simultaneity: Comparing Moving & Static Observers

    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...
  8. L

    Interpretation of Relativity of Simultaneity

    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...
  9. MattRob

    Lightning Bolts / Relativity of Simultaneity

    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...
  10. sjkelleyjr

    The importance of velocity in simultaneity

    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...
  11. A

    Special Relativity and the Relativity of Simultaneity.

    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...
  12. M

    Relativity of Simultaneity and the Perception of Time in Motion

    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...
  13. Coffee_

    Understanding Simultaneity in Special Relativity

    "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...
  14. F

    Special Relativity - "Simultaneity"

    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...
  15. D

    Is the Relativity of Simultaneity Always True?

    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...
  16. F

    Simultaneity and Spatial Separation

    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...
  17. J

    Does the relativity of simultaneity exist 'at a distance'?

    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...
  18. J

    Rotation and circular motion under different simultaneity conventions

    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...
  19. A

    Relation between relative simultaneity and velocity

    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...
  20. andromeda

    Is Relative Simultaneity Real?

    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...
  21. T

    Entanglement and Simultaneity

    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...
  22. A

    Time dilation, length contraction and relative simultaneity on Earth

    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...
  23. A

    Differences between different simultaneity conventions

    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...
  24. D

    Simultaneity & Digital Clockfaces: Understanding Relativistic Time Syncing

    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...
  25. Y

    Simultaneity, Rotation & Gravity: Agree?

    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...
  26. J

    Simultaneity in circular motion

    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...
  27. A

    Why do we always need to define simultaneity in relativity. The

    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...
  28. T

    Relativity Of Simultaneity Problem

    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...
  29. A

    Distance role in simultaneity measurement

    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...
  30. WannabeNewton

    Is Clock Synchronization Throughout a Time-Like Congruence Transitive?

    "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...
  31. J

    Simultaneity in 2 spatial dimensions

    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...
  32. PeroK

    Simultaneity between events in reference frames

    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...
  33. G

    Simultaneity at Speed of Light: Twin Paradox Explained

    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...
  34. T

    Paradox within relativity of simultaneity

    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...
  35. B

    Relativity of Simultaneity Issue

    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...
  36. A

    Role of distance in defining simultaneity

    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...
  37. J

    Einstein & Simultaneity: Two Questions

    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”...
  38. A

    About the convention of simultaneity

    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...
  39. Solarmew

    GRE Prep: Simultaneity Questions - Answer: No, Never

    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"...
  40. A

    Do rotating frames have planes of simultaneity?

    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...
  41. A

    Can Observers See the Future in Relativity?

    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...
  42. M

    Relativity of simultaneity objections

    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...
  43. D

    Unraveling the Implications of Simultaneity in Special Relativity

    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...
  44. D

    Relativity of simultaneity and parthood?

    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...
  45. D

    Simultaneity in Special Relativity

    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...
  46. Z

    Special Relativity, simultaneity and spatial separation

    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' =...
  47. ash64449

    Still confusion in relativity of simultaneity and time dilation .

    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...
  48. ash64449

    Relativity of simultaneity through lorentz transformation

    Hello friend, Can you give me an example that shows simultaneous events in one reference frame not simultaneous in other reference frame with the help of lorentz Transformation?
  49. R

    Does the relativity of simultaneity imply a sort of determinism?

    This came up at lunch today when a friend of mine brought up that he had recently watched the Nova episode of Fabric of the Cosmos where they talk about spacetime as a sort of loaf where relative motion has the effect of cutting different angled slices out of the "loaf" of space time (for those...
  50. tomwilliam2

    Simultaneity of Uncertainty Principle

    All of the statements of Heisenberg's uncertainty principle that I've read seem to state that there is a fundamental limit on the precision to which you can measure the values of conjugate pairs (like position and momentum) at the same time. So is this simultaneity necessary? I ask because...
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