Can somebody explain time dilation to me please?

Discussion in 'Physics & Math' started by maxjojo, Mar 13, 2017.

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  1. rpenner Fully Wired Staff Member

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    You are quoting from wikipedia: Absolute time and space
    In my opinion, this is not a good summary of Newton's views, because the quotation (which comes from the Scholium of Book I of his Principia Mathematica, immediately after the definitions) is part of a larger section where he goes on to show that absolute time is knowable by using the best clocks and mathematically correcting the time given by bad clocks. The section also introduces the composition of velocities which is one of the places where Newton's assumptions were wrong.

    In Newton's model of motion, the duration of relative time properly inferred between two events (Newton allowed correction for bad clocks) is always the same as duration of absolute time. Thus the absolute simultaneity based on absolute time is one that can be inferred and relied upon examining motion of a system (like the motion of clocks).

    However, Newton's model of motion was wrong, and his metaphysics of absolute time does not contribute to physics. They were guesses that might have been good enough 330 years ago, but not today.
    The motivation behind the repeated question doesn't seem to be based on anything in the current discussion.

    Talking about "the rate of time" is wrong thinking and the wrong way to understand time dilation, which is not a time-phenomenon but a trajectory-specific phenomenon of space-time. Of all the ways to get from (here and now) to (there and then) only one has the longest proper time measurement: the inertial trajectory.

    What Newton called relative time and relative space are related to what we call imaginary inertial Cartesian coordinate systems which are predicated on describing events and motion relative to a particular spatial origin and a particular state of motion called "at rest". Such a system is good for attaching numerical labels (coordinates) to places (here, there) and times (now, then) but these labels have no absolute meaning, and because the choice of which state of motion is called "at rest" is arbitrary, a different coordinate system may legally disagree than the events (here and now) and (there and now) happen at the same time. (Relativity of Simultaneity).

    In any such a coordinate system, given the same particular trajectory between events, we can apply a formula and calculate the proper time which would be measured by a clock sent on such a trajectory. Thus proper time is more physically real than coordinate time, even if it is trajectory-dependent. Shorter: proper time is more fundamental than coordinate time.

    And if we can calculate any proper time, we can show that the trajectory with the longest proper time is the one which is a straight line with constant velocity: an inertial trajectory. So independent of the choice of coordinates (independent of what Newton would call relative space) we may calculate the proper time of an inertial path that connects any two events, even if space is empty and nothing actually happens at those merely potential events. Therefore empty space has a geometry which respects the quantity between 4-dimensional points (potential events): c² (Δt)² − (Δx)² − (Δy)² − (Δz)² = c² (Δt')² − (Δx')² − (Δy')² − (Δz')² and so we glimpse space-time as something more fundamental than coordinates, or coordinate time.

    If one of the two points are fixed as (here and now) then the equation: c² (Δt)² − (Δx)² − (Δy)² − (Δz)² = c² (1 second)² describes a two-sheeted hyperbolic surface of all future event I may travel to inertially with a elapsed proper time of 1 second and a second sheet of all past events from which I could have travelled inertially to (here and now) with an elapsed proper time of 1 second. The asymptotic surface to these sheets are all events I could communicate by means of a signal traveling to or from me with speed c, which forms a double-cone of light-speed possibilities. This hyperbolic surface and light-cone is the same for all coordinate systems.
     
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  3. maxjojo Registered Member

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    Trolling? you make some strange assumptions. I have asked a few questions, I said I do not understand time dilation and how time can slow down, I never said I did not know any science.
     
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  5. exchemist Valued Senior Member

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    But it is not going off-topic. That's the point. There are two complementary phenomena in special relativity. One is the apparent contraction of length in the direction of motion relative to the observer, often called Lorentz contraction, and the other is time dilation. Both are consequences of the invariance of the speed of light with respect to relative motion.

    Nobody can understand time dilation without also taking on board Lorentz contraction, and the relationship of both to this invariance of the speed of light.
     
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  7. maxjojo Registered Member

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    Huh? for several posts now I have been trying to get an answer to my question, a question which is very related. Time dilation states that the rate of time slows down for an object in motion relative to an object in an inertia reference frame at relative rest.

    My question was , did Newton by absolute time mean that the rate of time was immediate?

    If Newton did mean this, then surely he would be correct and absolute time would be immediate and simultaneous to all ?

    I fail to see why you can't answer this relative to time dilation subject question?
     
  8. exchemist Valued Senior Member

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    It might help us if you can indicate what science you know and where your difficulties start. At present we are all guessing at your level of familiarity. Specifically, are you familiar with Newtonian mechanics? And, do you understand how waves propagate in a medium? Also, are you comfortable with simple algebra?
     
  9. karenmansker HSIRI Banned

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    So, maxjojo . . . . according to physics as we (think we) know it . . . . Theoretically, travelling at c, we can get anywhere (in the direction of motion) in no time at all!!! . . . . HAHA! (joke here!)
     
  10. maxjojo Registered Member

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    I do not see why you would need to know my level of knowledge, I can assure you I am not ''stupid'' and think that is all you really need to know about my personal life. My question does not involve algebra or light although I do know a little about the subjects.
     
  11. origin Trump is the best argument against a democracy. Valued Senior Member

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    OK I'm bored I will play a little more.
    What is that suppose to mean?
    He thought that 2 things that happen simultaneously in one frame would be simultaneous in all frames. He was wrong.
     
  12. exchemist Valued Senior Member

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    Aha. So a troll then.

    Anyone reasonable would have had no difficulty answering that question, which is not in any way about your personal life.

    Right, I'm out of this now. [click]
     
  13. maxjojo Registered Member

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    What does immediate normally mean? there is no ''spacing'' between increments.


    He would only be wrong if time had a slower rate than immediate?

    added-
    immediate
    ɪˈmiːdɪət/
    adjective
    1. 1.
      occurring or done at once; instant.
      "the authorities took no immediate action"
     
  14. maxjojo Registered Member

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    I think you are rather rude, I am a lone female on a public forum and you want me to give things away that could give away my identity. No sir, I am not a fool.
     
  15. karenmansker HSIRI Banned

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    Ah, yes, in time (OP pun intended!) "the truth will out" . . . . In case you don't understand, Maxjojo, such responses as here (above) reveal another modus operandi of the forum . . . . "kill the messenger"! . . . . When members who are supposedly knowledgeable of the subject matter cannot sufficiently respond with sought answers, they simply degrade and insult the questioner's integrity and sincerity by accusing them of being trolls! Granted, there actually are some trolls around here but they are few and easily recognized by their self-serving attitudes. May there perhaps be 'trolls' within the forum administration? . . . . I could name a few suspects! Hang in there Maxjojo!
     
  16. karenmansker HSIRI Banned

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    Maxjojo . . . . try this link . . .

    https://www.thoughtco.com/time-dila...4865b1df-a81c-452d-bd3c-0ce253b110a6-0-ab_gsb
     
  17. origin Trump is the best argument against a democracy. Valued Senior Member

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    I still do not know what you mean. Seconds are an increment of time. So it sounds like you are saying 10 second is immediate - which must be wong because it makes no sense. Are you saying we only exerience the moment?
     
  18. origin Trump is the best argument against a democracy. Valued Senior Member

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    No Newton was definitely wrong, time is not absolute, there is no question about it.
     
  19. gmilam Valued Senior Member

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    I could - but you apparently don't understand how the invariance of the speed of light leads directly to time dilation. So I was trying to make it a little more obvious.
     
  20. karenmansker HSIRI Banned

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    . . . . so, (NOT trolling!) . . . . . Origin, now you have piqued my interest. Since time is not absolute (but is relative) pls comment regarding the 'absoluteness' of distance, considering Lorentz-Fitzgerald contraction and c. Also, I am of the understanding that relativity deals mainly with the acceleration of frames of reference, pls correct me if I am wrong in this assumption. Perhaps we should discuss in a different thread rather than detract from this OP?
     
  21. maxjojo Registered Member

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    You must be pretending to not understand the question because I put the question in English but again I suppose for your amusement of taking the ''mick'', I will try to explain further more.

    A second is an increment of time passed. A second is not an increment of future time, FYI.

    We experience the ''now'' moment, the next ''now'' moment is adjoined to the previous ''now'' moment with no spacing between the ''now's'' . Time is continuous and the next ''now'' is immediate. There is no distance to contract when immediate is ''adjoined''.
     
  22. rpenner Fully Wired Staff Member

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    Newton is not considered an authority in physics. Empricial observations of phenomena are the authority in physics and we humans do the best we can to construct general frameworks to reliably and precisely predict all behaviors over wide domains of phenomena. At one time, Newton's physical theories related to motion, momentum and gravity were considered the best frameworks humans had, but we got better ones in 1905 and 1916.

    Newton is and always was wrong about absolute time, and the evidence for this began mounting up fast between 1859 and 1908. Some of this evidence is discussed in post #38. Nowadays everyone who successfully gets from place-to-place with SatNav helps prove Newton wrong.

    As a consequence of the demonstration of the contra-factual nature of Newton's Absolute Time, there is no Absolute Simultaneity, and the idea that "the present" or "now" has universal meaning is a fiction which requires humans to collaborate on an agreed upon standard trajectory for the legal and social purposes so that we all synchronize our clocks the same way. Having the bulk of humanity living near sea level on the same planet is the only thing that makes this fiction a reasonable-seeming lie. But when you test this lie with precision instruments or with abnormal situations, like sending humans into space, it begins to reveal itself as tawdry social construct devoid of universal applicability.
     
    Last edited: Mar 15, 2017
  23. exchemist Valued Senior Member

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    And you think that helps?
     
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