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The Universe is Pretty Big

Posted by michael on from the duh dept.

Psiolent writes "According to a recent article on Space.com, the universe is pretty big (156 billion light years across, to be more precise). Some recent research examining 'primordial radiation imprinted on the cosmos' has led to this conclusion, as well as a few others. This finding is particularly interesting considering the universe is only 13.7 billion years old (which would mean the universe has been expanding faster than light travels), but the article does a good job addressing this seeming paradox."

4 of 134 comments (clear)

  1. obligitory Douglas Adams Quote by Adrick42 · · Score: 4, Insightful

    Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the drug store, but that's just peanuts to space.

    Douglas Adams
  2. Re: Excerpt from the Weekly World News ?!?!? by Corvus9 · · Score: 5, Insightful
    The frame of reference is given in the quote; "us". That is, Earth. According to the Big Bang model, the universe expanded from a point. Since every place was once at that same point, every place has an equal claim to be the "center of the universe". Picking Earth is just as valid as picking any other place.

    There's another good reason to pick Earth as the center; if the universe is 13.7 billion years old then there is no way that anything - light, gravity, particles, aliens - from farther than 13.7 billion light years has reached us. We are at the centre of a 13.7 billion light year sphere containing everything which we can possibly observe.

    Not only does this not rule out the possibility of light which hasn't reached us yet, it is defined by it. This observable universe, which some have called "the cosmos", expands by 1 light year every year, as light further out has time to reach us. The entire universe could well be much larger than this; we can only theorize.

    By the way, the observable universe is very symmetrical in every direction, so we can consider ourselves to be at the centre even in a literal geometric sense of the word.

  3. not symmetrical last time I observed it... by Roman_(ajvvs) · · Score: 3, Insightful
    The placement of earth in its galaxy has no symmetry and the placement of the galaxies on the observable universe is anything but symmetrical

    In addition to this, the observable universe has no visible boundaries which could be deemed symmetrical, as what we observe is not so much the universe itself but the contents thereof. Since the contents aren't spread symmetrically or in any particular order for that matter, any observed boundaries can't be symmetrical.

    If you can't see where it ends, does that mean it ends where you no longer see it?

    --
    click-clack, front and back. I'm not moving this car otherwise.
    1. Re:not symmetrical last time I observed it... by hajihill · · Score: 3, Insightful

      Okay, well.....

      I have a couple more questions... which may only serve to indicate my ignorance in both posing the above issue and asking these questions....

      Taking this quote into consideration:
      "One seemingly paradoxical consequence of Hubble's observation is that galaxies sufficiently far away will be receding from us at a velocity faster than the speed of light. This distance is called the Hubble radius, and is commonly referred to as the horizon in analogy with a black hole horizon."

      Wouldn't it be assumed that, while the Universe is definitely expanding, the distance being observed is simply this "Hubble Radius"?

      How could we ever make realistic, meaningful observations about the size of the universe when we acknowledge, by means of this and general relativity that at a certain point the expansion of the universe prevents us from observing things more than a specific distance away, for when they reach this distance, defined conceptually by this Hubble radius, they would essentially become unobservable?

      To rephrase this you could say that when things get far enough away they will be receding, with the expansion of space-time at a rate faster than the speed of light, and light coming from them will no longer be observable.

      Wouldn't this explain why the universe has this 'symmetrical' appearance from our point of observation?

      Wouldn't it make more sense to say that this 13.7 billion light-year radius says something not about the size of the universe but in fact about it's rate of expansion?

      --
      Of blankness, I know nothing.