If the universe is much more bigger

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Saint, Sep 14, 2019.

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  1. geordief

    geordief Valued Senior Member

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    The source of the light (presumed because we cannot receive it) and the observer (us) is receding from us at a speed greater than the speed of light as a result of the increase in distances caused by expansion.

    As I have (hopefully correctly) heard . I think it is mainstream cosmology.
     
    geordief, Sep 16, 2019
    #21

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  3. Saint

    Saint Valued Senior Member

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    the older the universe, the bigger it is.
    true?
     
    Saint, Sep 16, 2019
    #22

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  5. kx000

    kx000 Valued Senior Member

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    This universe we see as outer space was born in fire and will die in it, but existence is eternal alpha and omega.
     
    kx000, Sep 16, 2019
    #23

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  7. geordief

    geordief Valued Senior Member

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    It may depend whether it is expanding or contacting.

    For now it seems to be expanding - and so getting bigger.
     
    geordief, Sep 16, 2019
    #24
  8. Michael 345

    Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Number of points I checked on over night

    1/ doubtful anything traveling faster than light (while there does appear to be a discrepancy in this regard)

    2/ a Galaxy which we were observing at the edge of our Universe may disappear agreed, BUT not because of it receding faster than light. Even if it was, its light emitted in our direction, would still reach us
    I would vanish because not ENOUGH light was reaching us

    3/ reason for acceleration of edge of Universe Galaxies

    This is puzzling

    Is there something out ahead of our Universe edge pulling? Doubtful. It would require the object to either be stationery or also heading away with our Universe trailing along

    Is there something within our Universe pushing? Doubtful.

    Is the expansion the Big Bang still in operation? Could be. With nothing, outside, in the way to slow down expansion, and only gravity, internal to the Universe, which does not appear to be working no reason for expansion to continue. Acceleration is another matter

    I disagree as currently it appears the Universe is headed for, what is called The Big Rip, where expansion is never ending and every single atom ends up alone

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    Michael 345, Sep 17, 2019
    #25
  9. James R

    James R Just this guy, you know? Staff Member

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    There's a connection.

    Consider the average distance between galaxies, for instance. We observe that this is increasing with time, with all the galaxies moving away from one another, on average. Hubble's law says that the further away from us a galaxy is, the faster it is receding from us. We can use this observation to work out the elapsed time since all the galaxies were in the same place, which is the time since the big bang, or in other words the age of the universe.

    That's where the 13.8 billion year figure comes from.

    Although, it just occurred to me that you might be referring to the total size of the universe - not just the observable universe. There's no way to determine the total size of the universe, since we can only see the things that light has had time to travel to us from.
     
    James R, Sep 17, 2019
    #26
  10. James R

    James R Just this guy, you know? Staff Member

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    The expansion of the universe is not primarily an expansion of things in space, but an expansion of space itself. The rate of the expansion of space is not limited to the speed of light. The speed of light is the speed limit for things travelling through space, not the speed limit of space itself.

    If space is expanding faster than the speed of light, then light emitted from a region of space that is receding from us faster than light could not reach us.

    The cause of the acceleration is given the name "dark energy". It's almost like an anti-gravity force pushing the universe apart. More accurately, it's an extra thing that causes space itself to expand over time.

    We don't yet know exactly what this dark energy is. We only see what it does.

    Even without dark energy, there are a number of possible scenarios for the universe's evolution. What would happen, in the absence of dark energy, would depend on the average mass density of the universe. If that is higher than a certain critical value, the universe's expansion will eventually stop, then it will collapse, eventually ending in a "big crunch". If the mass density is less than or equal to the critical value, on the other hand, then the universe will continue to expand forever, although at a decreasing rate over time. None of this, however, explains how the universal expansion could be accelerating, which is what we observe. That's why we need dark energy.

    The big rip is an effect of dark energy.

    Of course, it's possible that either our observations or our explanations or both are wrong, such that there is no dark energy...
     
    James R, Sep 17, 2019
    #27
  11. James R

    James R Just this guy, you know? Staff Member

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    Please do not preach in our Science forums.
     
    James R, Sep 17, 2019
    #28
  12. Michael 345

    Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Does that mean

    SPACE ie NOTHINGNESS ie just space and not the contents ie no fields or the other contents Galaxy stuff is being left behind?

    Or SPACE is carrying the stuff in it - field's and Galaxy stuff - with its expansion?

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    Why?

    You are saying a (theoretical powerful enough spotlight shining towards us) will not travel to us but trail along behind the spotlight?

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    OK ? Pushing or pulling ???

    Astronomers theorize that the faster expansion rate is due to a mysterious, dark force that is pulling galaxies apart

    https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy

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    Amen to that - not preaching

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    Michael 345, Sep 17, 2019
    #29
  13. geordief

    geordief Valued Senior Member

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    I was indeed-and I also made the point a little earlier (post#18) that we may have to specify whether we mean the observable U or the total U as that misunderstanding can lead to us talking past each other.
     
    geordief, Sep 17, 2019
    #30
  14. James R

    James R Just this guy, you know? Staff Member

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    Michael:

    The better picture is that space carries the stuff along with it. Alternatively, you might like to imagine "more" space being continuously created in the gaps between the stuff.

    An analogy might be to imagine a large rubber sheet with galaxies and things drawn on it. Pull on the edges of the sheet and all the galaxies move apart from one another. In one sense, they move with the sheet. In another sense, they stay where they were before on the sheet, but "more" sheet is created in between them as it stretches.

    Think about rolling a marble along the rubber sheet. If, as that is happening, you simultaneously stretch the sheet at a great enough rate, the marble will never reach something else on the sheet that it is rolling towards.

    It doesn't matter. Physics makes no distinction. A force is a force.

    Sometimes you'll see arguments on the internet about whether gravity is a "push or a pull", or silly things like that. A force is a force. Forces can be attractive or repulsive. Whether you want to call them pushes or pulls is up to you, and possibly a matter of perspective.
     
    James R, Sep 19, 2019
    #31
  15. Michael 345

    Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    However what you are stating seems to negotiate the Michelson–Morley experiment

    Also if space is expanding (like a rubber sheet with the stuff of the Universe embedded within it), and at a rate faster than light, then the embedded stuff is moving faster than light

    Something stinks in Holland

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    Michael 345, Sep 19, 2019
    #32
  16. geordief

    geordief Valued Senior Member

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    Yes ,something like that . It doesn't make sense to me either ,but it apparently matches what is observed.

    I don't understand expansion (or inflation) either but my incomprehension has no bearing at all on the theory. (I do understand James' rubber sheet analogy but it is just an analogy I assume)

    Yes ,c is does not apply when it comes to expansion/inflation ,it seems.
     
    geordief, Sep 19, 2019
    #33
  17. Michael 345

    Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Well my take, the section where you note, apparently matches what is observed, I would reply, concentrate on apparently.

    The obs are incorrect or being incorrectly matched

    More data required me thinks, or more betterer explanations - I know that feeling

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    Michael 345, Sep 19, 2019
    #34
  18. Xelasnave.1947

    Xelasnave.1947 Valued Senior Member

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    The Big Bang theory/ model has the universe at about 13.5 billion years old. This number gets adjusted but mine is upto date but maybe add another .2 billion years.
    What is hard to understand is that the size of our observable universe of is now some 90 billion light years diameter. We are the centre..you personally are at the centre so if anyone asks put them straight and tell the that you are at the very centre of the universe, observable universe that is. How can important is that.
    The expectation is the universe being 13.5 approx years old means that it's diameter must be 26 approx billion years but then the expansion factor means that it grew to at least 90 billion years diameter in those 13.5 billion years.
    However it may be the universe is larger. Observable recognises our ability or lack to see further... The " observable
    " In the observable universe tells us our limitation on observation. But it is big really really big and them some. The suggestion is objects at the edge of our observable universe will eventually disappear as their light can never reach us as they move past a point.

    Alex
     
    Last edited: Sep 23, 2019
    Xelasnave.1947, Sep 23, 2019
    #35
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