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Time/electromagntec spectrum and causality

  1. Sep 19, 2011 #1
    A question I have puzzled over for a year now is how we define time. We chose light as the fastest thing we know (currently) as our mathematical limit, as only massless particles can only reach c our calulations of Gr and Sr are based on this. Unitl I started hearing terms of backwards in time (relatively from the observer) I had no issue with that. Now recongnizing that the tachyon is still not proven, It is as hypothecally accepted as the higgs boson etc.
    The properties of the tachyon is that its slowest speed is c. I started wondering how our mathematics of relativistic effects would shape were we to base our mathematics of Gr around its maximum speed, rather than stating it travels backwards in time, which is a clear violation of causality. Part of the problem I see is that human observation can only percieve in the elctromagntic spectrum, therefore our perception of time must also follow those rules shown by Gr.
    There have been numerous experiments that perceptually have faster than light observations the term " information cannot travel faster than light' Is often quoted to keep those effcts from violating causality, but could not the illusive tachyon carry information ?
    Or is the information it carries also going to be described as travelling backwards in time in violation of causality.
    I am curious as to how the professional physicists explain this dilemna I have.

    For the record I do trust Gr in its accuracies and predictions and am not atempting to debunk it, merely stating a possibility, the whole laws of causality problem in regards to tachyons and those experiments. (If I understand what little I do involve wave manipulation of light through a material giving the effect of reflected light prior to light beng sent).
    Speaking of tachyons, What would be its maximum speed? The speed where how we define bakwards in time matches up with the speed of light were the tachyon travelling forward? I have a hard time visualizing the limits of the tachyon on a 4-d model its like saying that if a photon were to exceed the speed of light it would reverse course back the way it came on its 4th degree bearing. Hope I make sense with that last statement.
    Last edited: Sep 19, 2011
  2. jcsd
  3. Sep 19, 2011 #2


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    Staff: Mentor

    I was under the impression that the tachyon was all but disproven. Perhaps I was mistaken?
  4. Sep 19, 2011 #3
    To be honest I don't know if it is or isn't I've been reading the information of thermodynamics articles posted on wiki (in an attempt to better understand the term information as it applies to quantum mechanics etc) Also to undertand better its causality implications and at this point I can't decide which is more correct Penrose, Hawkings or Preskill? Whats the latest findings or accepted definition in regards to the blackhole paradox?

    In November 2010, Penrose and V. G. Gurzadyan announced they had found evidence of such circular patterns, in data from the Wilkinson Microwave Anisotropy Probe (WMAP) corroborated by data from the BOOMERanG experiment.[4] The significance of the findings was subsequently debated by others.[5]

    this is from one of the wiki pages on the blackhole paradox any verdict on the debate?
    its hard to understand something thats still heavily under debate lol and the whole information term is something I lack understanding in.


    this is what I've been currently poring over.

    this is my understanding of the tachyon as other articles I've found have thus far been less reliable

    http://en.wikipedia.org/wiki/Tachyon I would enjoy more detail and up to date articles on the subject.
    Last edited: Sep 19, 2011
  5. Sep 19, 2011 #4


    Staff: Mentor

    Do you have a mainstream scientific reference for this topic?
  6. Sep 19, 2011 #5
    I wish most of my understanding on the recent has been through this site and a few other forums, Space.com articles, Scientific America wiki and sometimes youtube but in all these sites its tricky deciding which is more reliable or correct though I'll trust Space.com and Scientific America over youtube and wiki for obvious reasons.
    My profession is a Systems controls technician so this is all self study and interest for me.
  7. Sep 20, 2011 #6


    Staff: Mentor

    The reason I ask is that the rules of the forum do not permit discussing speculative topics. Tachyons are kind of borderline. They are not forbidden by theory, but they have not been detected either. So there may be mainstream scientific work on this topic, which would be appropriate to discuss. Otherwise I suspect the conversation will necessarily remain at the "tachyons violate causality" stage, which I assume would not be satisfying to you.
  8. Sep 20, 2011 #7
    I've wondered about how to define the rules in that regard, From my viewpoint string theory with 11 dimensions, multiverse models such as bubble universes (recent article in last months edition of Scientific America), Higgs boson and tachyon are all published speculations as none of the above are proven. How does the non Physicist learn what is no longer considered main stream science and which is not allowed discussion in the scientific community as represented by this forum?
    A search on Wiki does not provide that answer I've seen posters mention tachyons recently on this forum so I thought those would be considered relatively safe.
    I honestly don't know if discussing the scientific article mentioned above would be safe even though some big name scientists have spent A lot of time working out their mathematical models to try to support the bubble universe theory or the cyclic theory universe etc...
    I have no problem with the rules of the forum as I can understand the reasoning behind them, its one of the reasons I consider this one of the top 13 forums/40 forums I visit. I hope the site can understand that to the non phycisist that there is a LOT of material on the internet that one such as myself has to sort through with great trouble trying to seperate the facts from the fiction or to understand what is main stream or not.

    In regards to the above post I posted that question as the "speed of information " justification I've come across in FTL findings (in regards to recent experiments) is confusing as a protection of Gr theory.
    Reading the above posted links in regards to quantum information terms just left me more confused more specifically in regards to the blackhole paradox. Tachyons is merely a more recognized term of an FTL particle in regards to the question.
    One of my confusions in information loss is that in order to observe something we must naturally rely on the electromagnetic spectrum, We can only see light which is the fastest form of the elctromagnetic detection we have. All of our instruments of measure rely on the electromagnetic, so one cannot help but wonder if the backward in time terminology, how we measure time itself (and its resultant mathematics) is merely limitted by those factors.
    As far as I know the law of causality has never been disproven so I would think that its one of the most fundamental of all the laws/theories above. So I'm looking for a better understanding on how the "speed of information" (which from what I can tell also relies on the electromagnetic measurements) handles the FTL violations of causality problem.
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