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Thread: Observable Universe

  1. #1 Observable Universe 
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    If the Universe is only 13.7 billion yrs old why is the observable universe 46.6 billion lightyears? I'm really confused on this, shouldn't it be less than 13.7 billion lightyears? Or am I mistaken about something?
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    In reply to ThirdReaction, re: your #1 post.

    An excellent question! Although I believe the 46.6 fig. refers to an estimated distance of "observability" due to light-shift or emanated radiant factors...I think the estimate is due to applying

    distant velocity factors to various entities since "BB", as in a "general increase in velocity over distance" using a template of "further=faster" in relation to the observer.

    I'm sure "Physicist" or "Jilan" know a more complex "official" way to explain the dichotomy of "age of Universe vs. extreme observations".

    This would generally be regarded as an "SR" issue...and the extrapolations of math can be tricky (not my forte')

    ......

    (Thanks for reading!)
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    I have absolutely no knowledge of "SR" lol I think it has "cannot travel faster than the speed of light" in it but that's all I know. However even that confuses me. I think speed is relative so objects can be traveling faster than the speed of light (yea I'm getting off topic but this interests me) but only as the speed is relative to another object. Never faster than the light produced in it's own "speed" such as we can't travel faster than the light produced in our sun but we could technically travel faster in relation to the light produced in another star. This is just a hypothesis that I have yet to develop the mathematical skills to test or actually properly hypothesize. Back to the BB and the observable universe. Could the light we see have been produced by these stars many years ago (billions) back when the stars were closer to us and it is only since then that the stars traveled further away? Would that properly explain why we see the light from stars located that far? And back to the 'faster than the speed of light' thing, like if you were riding a spaceship going 99.9% of the speed of light and you fire a projectile that also goes 99.9% the speed of light, it should be going faster than the speed of light in relation to what you were relating to but slower in relation to you. Does that make sense? Also to Physicist or Jilan or anyone else who can give me a more complex view on this, I would be very interested in knowing why my view would be wrong or right or w/e.
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    In reply to ThirdReaction, re: your #3 post.

    You are jumping into a very contentious topic that involves at least a books' worth of reply! "KJW" a "super-mod" here (what does "super" mean? IDK) can likely give a more satisfactory

    answer than myself..."SR" paradoxes can be debated ad infinitum, and still no positive answer. As for me, I have been reading concerning the "meanings and implications" of SR for

    forty years, and I understand less now than when I started! (the more I know, the less I can understand)

    ......

    Your spaceship/projectile scenario is the same one I have read hundreds of times, in various formats (such as the "Twin Paradox") and any answer I could give you would fall into the

    "alternate theory" section...at any rate, I wish you luck in this "comprehension of SR" as you will need it! (even Einstein had problems w/ it, and he WROTE IT)


    (Thanks for reading!)
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    40 years?!? I can't even picture that amount of time to be honest, being half that age. But I would love to know anything that you do know (what fields you are knowledgeable about etc). I'm here to learn, I have a high capability for learning but a low tolerance for being taught if that makes sense. I love things I don't comprehend completely, complete knowledge of something makes that something boring in my eyes. What are some good resources for learning SR? I started reading some of the threads on it in that section but I didn't even complete precalc completely so I'm at a total loss in the mathematical part of it.
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  6. #6  
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    Quote Originally Posted by ThirdReaction View Post
    If the Universe is only 13.7 billion yrs old why is the observable universe 46.6 billion lightyears? I'm really confused on this, shouldn't it be less than 13.7 billion lightyears? Or am I mistaken about something?
    The starlight that was emitted so long ago was emitted when the universe was much smaller than it is now. In the meantime the space between the stars has expanded. So we see these distant stars in the position they were then, not where they currently are.
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    So how is the observable universe 46.6 billion lightyears in radius? If we are seeing the light where it once radiated from, it should still be 13.7 billion lightyears right? That should be the endpoint of what we see, however it's not. How is what we see 46.6? Or is that just conjecture on the stars current position and not based on the light we see?
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    The 46.6 billion light years is a calculation based on the redshift. I would use the word calculation rather than conjecture.
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    How did they get 46.6 billion light years if it's impossible to travel faster than the speed of light? Or is it that particles 'blown out' for lack of a better word of my knowledge during the Big Bang went faster than the speed of light creating matter further away than what would be possible in other circumstances. Please forgive my ignorance on this topic but it's confusing given the extent or lack thereof of my knowledge
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    In reply to ThirdReaction, re: your #5 post.

    Don't to be too impressed w/ the "40yr." figure, I was referring to reading own my own...I have never studied physics formally (just medicine)

    Stay w/ "Jilan", she has a proper education...in England, you'd best "keep your socks up!" in formal classes there! Also, as I said, "Physicist" knows theory well also.

    ......

    In terms of "absolute answers" in SR...they will be hard to establish, as much of the topic is extrapolated theory using mathematics as a "counter-weight" to establish validity.

    At some point, almost everything is a "best guess" w/ SR...since it is extremely difficult to establish what constitutes fundamental "causalities".


    (Thanks for reading!)
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  11. #11  
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    That's awesome. I've heard that universities in England are much better than the ones here in the USA. And 40 years of reading on your own is impressive. I usually can't keep reading on a single topic for longer than a few months, however math, physics and cultural anthropological books seem to stay on my mind for longer than other topics.
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    Quote Originally Posted by ThirdReaction View Post
    How did they get 46.6 billion light years if it's impossible to travel faster than the speed of light? Or is it that particles 'blown out' for lack of a better word of my knowledge during the Big Bang went faster than the speed of light creating matter further away than what would be possible in other circumstances. Please forgive my ignorance on this topic but it's confusing given the extent or lack thereof of my knowledge
    The phrase "impossible to travel faster than the speed of light" needs to be understood very carefully not to apply to space itself; the expansion of the universe can have any speed. So, as Jilan correctly says, the observable universe is of more than triple the radius than you would expect on the basis of the age of the universe alone, because the universe has been expanding all that time.

    Mind-bending stuff, eh?
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  13. #13  
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    Quote Originally Posted by ThirdReaction View Post
    How did they get 46.6 billion light years if it's impossible to travel faster than the speed of light? Or is it that particles 'blown out' for lack of a better word of my knowledge during the Big Bang went faster than the speed of light creating matter further away than what would be possible in other circumstances. Please forgive my ignorance on this topic but it's confusing given the extent or lack thereof of my knowledge
    The important thing to bear in mind is that the universe is still expanding and furthermore that expansion is accelerating. We can only see light from stars that was emitted up 13.7 billion years ago, but that doesn't mean that the stars are still only 13.7 billion light years away. The intervening space has been increasing in the meantime.

    You might want to read this
    Observable universe - Wikipedia, the free encyclopedia
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    So the "cannot travel faster than the speed of light" is false? Or is it that you can't travel faster but space can expand faster than light can travel across the same distance?
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    I don't think there is a limit on the rate of expansion of space. Here is a nice discussion on the subject.
    Curious About Astronomy: Is the universe expanding faster than the speed of light?
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    So objects never reach c in a local frame but in a universal frame because two objects are moving away from each other as space expands it expands further than light can travel in the same given time? Which gives the appearance of speed faster than light speed but it's not.
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    You need to Be careful here, information cannot travel faster than the speed of light, but that does not put the blockers on any faster than light phenomena. As this site
    Faster-than-light - Wikipedia, the free encyclopedia
    says
    " Rules that apply to relative velocities in special relativity, such as the rule that relative velocities cannot increase past the speed of light, do not apply to relative velocities in comoving coordinates, which are often described in terms of the "expansion of space" between galaxies"
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    In reply to ThirdReaction, re: your #11 post.

    It's unfortunate that an accumulation of knowledge has very limited value, at least in terms of "knowing a thing", (I have found this very appropriate where females are concerned, as in

    "you only think you know" what they are about) the more I know, the less I am able to accomplish w/ it, at least as far as physics theory is concerned!



    (Thanks for reading!)
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  19. #19  
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    Gerry, you are not alone. One approaches Physics thinking it will give you all the answers, but the deeper you get into it the more you realise how little we really know and the disappointed you become. I reckon you are in deep!
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    Have a read of this Scientific American Article, it explains it all in layman's terms:

    http://www.dark-cosmology.dk/~tamara...Am_BigBang.pdf
    Jilan likes this.
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    In reply to Jilan, re: your #19 post.

    I am not as "alone" as you might think...whenever I examine anything in physics theory, I do my best to say "what would Einstein think of this?"(50% me,50% him) and in this way try

    to arrive at an answer that least has some possibility of a "solid foundation". In my thinking, "GR" applies to all things...or it applies to none. It may SEEM that "Relativity" is ruled-out

    in regard to many theoretical posits of "SR" but I have no real reason to believe so...at least thus far in what I have read involving QM theory.

    I think there are far too many "valid conclusions" reached with regard to equations in SR...while completely ignoring the reality of "close at hand" examples of "how things work", such

    as our own Solar System. If we knew everything there is to know regarding how our own system works...the rest of the Universe would reveal itself.


    (Thanks fro reading!) Ta Ra!
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    When I think, I make it 100% me.

    Space can also expand faster than light can transverse.
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    Do we understand why? Or is the entire point not understanding why but knowing that it is?
    Crush a bit, little bit, roll it up, take a hit
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    Sorry, I responded more because I felt, Gerry, was a retard.

    We still don't understand why gravity works. (Curvature of space..? Graviton...?) So, I think we should do the best we can do and let future generations come to a better understanding of things where it is applicable. But, that doesn't mean I wont try to do it now.
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    In reply to beer, etc.

    This particular "retard" has a gravity concept that is real...and it WORKS, no matter how many fellow retardates deny it. (keep on making personal comments, we'll see who wins!)
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    Quote Originally Posted by ThirdReaction View Post
    Do we understand why? Or is the entire point not understanding why but knowing that it is?
    We don't understand this yet, but lots of people are working on it. Aren't we lucky to be alive now?
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    Quote Originally Posted by Gerry Nightingale View Post
    In reply to beer, etc.

    This particular "retard" has a gravity concept that is real...and it WORKS, no matter how many fellow retardates deny it. (keep on making personal comments, we'll see who wins!)
    Apparently, in your post, you forgot to show us how it works.

    By all means, show us your Noble Prize winning material...
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    And the old geezer runs away...

    So sad. Was waiting to be educated by his monumental accomplishments. His intellect. His breakthroughs...
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    Such unkindness in one so young.... Sigh!
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    In reply to BeerW/Straw, re: your numerous pithy comments of nothing.

    My name is Gerry Louis Nightingale, born 4/21/54 in Garden City, Mich. My current address is 393 N. Canal St, Cave-in-Rock, Illinois. My mailing address is P.O. Box #152 (62919)

    My cell # is (618) 294-6289...available betw. 2pm to 4pm.

    .......

    I am not intimidated by you or anyone...ever. I don't run...ever. (you want my DD-214?) Feel free to drop me a line...or better still, PLEASE show-up at my paid-for home (Google it, it looks

    much better now than the photo!) and tell me to my face "what a retard" I am...I will show you what the practical applications of "matter in motion" really mean in terms of physicality.

    The only "so sad" to me is that internet "trolls' seem to be unable carry thru w/ any sort of meaningful dialogue...or their threats. I personally would RELISH the opportunity to "explain"

    things to you and others of your ilk on a personal basis just "who is superior to whom" on whatever basis you have in mind.
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    A further addendum...you cannot post "alternate theories" on this thread...so I didn't. If you read and do NOT understand the content of anything I write, then ask "what do you mean"

    instead of insults and accusations and veiled comments of implication that "you have knowledge and I don't" or that I don't understand the meanings of "real science". I do understand,

    and I don't agree w/ many so-called "facts" that have nothing to do w/the realities of gravity and energy as established by "Relativity".
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    And you are not making any sense. This is consistent with you, however.

    Still waiting for your supreme understanding of gravity. But of course, we all presume you're going senile.
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    Quote Originally Posted by Jilan View Post
    Such unkindness in one so young.... Sigh!
    But who's fault is it?

    I'm reacting to the environment.
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  34. #34  
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    At some point one grows up and stops blaming the enivironment.
    Some people get there quicker than others. Some never get there.......
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    If you're old, don't try to change yourself, change your environment. - B. F. Skinner at BrainyQuote

    I'm nsorry, I thought this could be a physics forum, and not one just for cranks.

    Gerry, is nothing but a hypocrite.
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    Oh...I forgot! I don't really have any interest in being awarded a "NOBLE" prize...the "NOBEL" would be nice, tho...I can put the money to good use.

    >>>is this an example of your skills? >>>"Noble"<<<? (I suggest you study a few more years...starting with proper nouns)
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    I suggest you study physics.
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    In reply to ThirdReaction, re: this thread.

    Please accept my apologies for being a co-enabler of your "topic thread" being hijacked, courtesy of "BeerW/Straw".

    I'm sorry I allowed myself to be goaded.

    Gerry N.
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    Lie.

    What would Jesus do? 50% Jesus! That's what I think, really!
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    Its all fine. I choose to ignore personal rabble on posts. So do you think we will ever be able to find out why space expands as fast as it does?
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    In rely to ThirdReaction, re: your #40 post.

    I assume you are asking me..."we will ever find out..." and my answer is "I don't know". There are so many conditions being applied to "expansion" that I have difficulty envisioning

    how to "juggle" them all. It is possible (IMO) that expansion is not 'increasing the square of velocity in relation to distance from an observer". I have no idea of the mechanisms that

    could stimulate such responses, never mind the postulates that dictate that it is actually occurring!

    I cannot follow such a line of rationale...an idea that proposes that extremely distant galaxies may actually have a speed approaching light itself. Taking the next logical step, such a concept

    would dictate that further order of distance may actually mean a galaxy might be, or would be, exceeding lightspeed. (at least that seems to be the implications to my understanding)

    If one states it is actually an "expansion of the spacetime continuum" it would still mean that some distant galaxy is embedded within the continuum and is "scurrying to catch up".

    ......

    I think Physicist may have a better grasp of this than I do, or one of the "Mods". (Jilan knows this stuff MUCH better than I do...I can't wrap my head around it. My "thinking cap" won't

    allow it!)

    (Thanks for reading!)
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    Interesting. What do you mean by "some distant galaxy is embedded within the continuum and is "scurrying to catch up"" I feel as if that implies that there is galaxies outside the spacetime continuum which should be impossible right? Or would it just be improbable?
    Crush a bit, little bit, roll it up, take a hit
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    I guess the best is to make quantitative models to describe the workings of the universe. From observations from instruments like COBE, WMAP, and HST. Understanding of things is pretty much dictated on how much is required. Newton's model of gravity is fine for apples falling from tress, but General Relativity is needed for GPS satellites. Negative pressure could be one way to describe the workings of Dark Energy. I, however, still don't understand rapid inflation:

    "t  10^-34 s. By this moment the universe has undergone a tremendously rapid
    inflation, increasing in size by a factor of about 10^30, causing the formation of
    matter in a distribution set by the initial quantum fluctuations. The universe
    has become a hot soup of photons, quarks, and leptons at a temperature of
    about 10^27 K, which is too hot for protons and neutrons to form."

    (This is a copy and paste from the pdf Fundamentals of Physics 9th Edition. I have a hard copy of the 8th which says the same exact thing. Haven't looked at the 10th edition though.)
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    In reply to ThirdReaction re: your #42 post.

    What do I mean by "embedded?" Okay, let me try to explain...think of a pool of water. There are various bodies within the water. Apply an expansion factor, such as heat...and the water

    expands in direct corollary w/the input...the objects in the water respond to the motion of the water, in effect they are entrained and must move as the water dictates they should.

    ......

    The above paragraph is not a direct analogy to expansion...but it illustrates what I meant by "embedded in a given timespace continuum". The entities in the water demonstrate a similar

    characteristic to the movement of a Galaxy, just substitute "space" for "water"...the greater the stimulus, the greater the reaction to the stimulus.

    What truly puzzles me is the "source' of the stimulus, and to "where" or "what" is a Galaxy moving? In relation "what" continuum? A "void" of nothing, maybe? I would think so, since

    the presence of "something outside" our Universe presents what I think of as "currently insoluble".


    (Thanks for reading!)
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