Light years?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by wegs, Jul 16, 2022.

  1. Dicart Registered Senior Member

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    465
    This delay of the speed limit doesen't imply that there is not a universal now (even when parrots will not say this).

    https://arxiv.org/html/gr-qc/9911111v8

    This only say that at a distant location you can not see this universal now (because you see things using light per example), and this point if total obvious.

    The proof that a universal now exists, is that you can take any space traveler from any point of the space, let them travel toward a particular location and... every of them will arrive at the same "now" (so no multiple universe here).
    Did i forget to mention that reality ("now" is the reality) is what happens localy ?
     
    Last edited: Jul 18, 2022
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  3. Dicart Registered Senior Member

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    Science is not saying Dave is a good guy so i will believe him and not Dicart.
    Here you are doing politic, not science.
    Science imply using his own brain, try it.
     
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  5. DaveC426913 Valued Senior Member

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    Please, for the sake of the OP, try to stay on-topic.
    Trolling is not on-topic.
     
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  7. parmalee peripatetic artisan Valued Senior Member

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    Jesus. I can't quite figure what you're saying here, but what little I do think I grasp kinda seems like advice which perhaps you oughtta heed.
     
  8. Dicart Registered Senior Member

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    It is you who do some derivation with your "universal now" considerations.
    Who will really understand this ?
    Look, there are some specialists trying to understand it (you not for sure, you already know you know everything) :
    https://www.quantamagazine.org/a-debate-over-the-physics-of-time-20160719/

    Perhaps you will not only read the title and learn something new ?
     
  9. Dicart Registered Senior Member

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    465
    Sorry i dont understand when somebody speak in slang.
     
  10. Seattle Valued Senior Member

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    "I can't quite figure what you're saying here, but what little I do think I grasp seems like advice which perhaps you should heed."
     
  11. parmalee peripatetic artisan Valued Senior Member

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    It's fine to expand and expound upon another's explanation, but stating that said explanation is "wrong"--as you do in post# 13--simply because it is not complete and comprehensive is not helpful, and it only confuses matters.
     
  12. Dicart Registered Senior Member

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    465
    In this case the question should have been formulated in physics (because it is a basic question), not in cosmology.
    "Do i see the things like they are ?" Not; there is a speed of light.
    Oh my gosh, its incredible !
     
  13. wegs Matter and Pixie Dust Valued Senior Member

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    9,253
    But, it is incredible. Maybe for the first time, I’m realizing just how incredible the concept of light years really is. I was (in my mind) confusing it with time (as a measurement) and not as a measure of distance. Thus, this thread came to be.

    As an aside, threads evolve. As more people chime in, the answers sometimes beg more questions. That’s the point of these discussions.

    Why don’t you just discuss the topic with others, and not question the motives of everyone in the thread, Dicart?
     
  14. Dicart Registered Senior Member

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    465
    Try to use your brain.
    If you have a question, why dont you try to answer it yourself ?
    Here you already have all the facts, and you think i am the one who agress other ?
    I just give punches back, and you can verify this reading it carefully.
    But you can also just repeat what other say. It is up to you.

    I will help you.

    This is a very clever guy beeing able to identify my motivation ...
     
  15. parmalee peripatetic artisan Valued Senior Member

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    Not a precise match, but I would posit that you were committing what is sometimes termed a numeracy bias or a precision bias:

    Precision bias is a form of cognitive bias in which an evaluator of information commits a logical fallacy as the result of confusing accuracy and precision. More particularly, in assessing the merits of an argument, a measurement, or a report, an observer or assessor falls prey to precision bias when he or she believes that greater precision implies greater accuracy (i.e., that simply because a statement is precise, it is also true); the observer or assessor are said to provide false precision.

    https://en.wikipedia.org/wiki/Precision_bias

    It's hardly the most heinous of offenses, but it does sometimes make things needlessly complicated, and confuses rather than illuminates.
     
  16. Dicart Registered Senior Member

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    465
    Do i really need to reply to this....?
     
  17. Bells Staff Member

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    Mod Note

    Whether you reply to a comment is up to you.

    How you decide to reply to it, however, is dictated by the rules of this forum. If you are unsure about those rules, you can access them here: http://www.sciforums.com/threads/sciforums-site-rules.142880/

    I would suggest you pay particular attention to the part about trolling and flaming.

    So here's how we are going to address this. You will receive an infraction for trolling and flaming this thread and the participants in it. If you persist in acting this way, you will be barred from the discussion. And if you can't seem to stop yourself, you will receive more infractions until *poof*, the system will automatically ban you from this site.

    I hope this clears up any confusion you may have.

     
    wegs likes this.
  18. Dicart Registered Senior Member

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    465
    The truth is you defend the trolls that drive users away, and that you never have recognized as such.
    Not sure why but the result is that this website now sucks and nobody really care about.

    Bye Bye (and i will not recommend this website for sure to anyone (more surely i will warn others that this website is full of trolls)) !!

    PS : You can safely ban me, i will never log in anyway.
     
  19. exchemist Valued Senior Member

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    Splendid, splendid!

    Bye.

    Please Register or Log in to view the hidden image!

     
  20. geordief Valued Senior Member

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    You could say that LA is (guessing) 10 walking speed days from SF or 1 cycling speed day ,or 6 car speed hours or 1 plane speed hour
    (Or 1 Trump corruption contagion second

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    )

    And ,maybe 1 tenth of a light speed seconds to get that same distance from LA to SF.

    So the light years is the same kind of a combination measurement, combining the speed of something with the time taken and giving a distance as a result


    You could measure the distance to the Sun from the earth as how long it would take a snail to get there if if could pull itself there eventually.

    Probably 10 followed by millions of noughts of snail speed centuries.

    8 light(speed). minutes is more sensible.

    You also asked about the speed of light if the emitting object was moving or accelerating with respect to the observer.

    As Dave (I think it was him) said the light would just be "red shifted" and the speed would be the same in a vacuum as if the emitting body was stationary


    That seems a little strange but it does seem true (and it is very important in the mathematics of relativity)
     
    wegs likes this.
  21. wegs Matter and Pixie Dust Valued Senior Member

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    Read something over the weekend that served as a light bulb moment (no pun)

    If someone were to drive to my house with the starting point being one mile away holding a sticky note that read “it’s 2 PM,” by the time the person arrives to my home, the sticky note is meaningless, because it’s 2:30 PM by that point. Because the speed of the car traveling to me isn’t instantaneous. (This coincides with what Dave posted in terms of there not being an indisputable “now” when it comes to space.)

    So, the light that I’m seeing from an object far away, has that same “delay effect” as the person traveling to me, except with light years, it’s much longer and the speed faster. One light year means it takes one year for the light of that object, to get to me.

    Has anyone in this thread or forum ever taught science in high school or college? Just wondering.
     
  22. DaveC426913 Valued Senior Member

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    18,935
    So now you're tapping on the lid of a can of worms.

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    That "object" cannot travel one light year in one year. No object with mass can travel at the speed of light.
    It can travel at just under the speed of light (say, 99.99%), but if it did so, it will have experienced the journey as only about 5 days long!

    But that's a whole 'nother thread.
     
  23. wegs Matter and Pixie Dust Valued Senior Member

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    Oh. I posted the light of the object, not the object itself. lol If something is one light year away from Earth, it will take one year for the light of that object to reach me seeing it. Yes?
     

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