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Power of inflation in relation to expansion

  1. Aug 4, 2012 #1
    how much more power had big bang in inflation theory than in standard expansion theory? (if standard expansion big bang = 1 )

    i assume it was over-c because of that power

    standard expansion would be 18000000 km/min

    and inflation... ?

    and after how much time did speed of light turn unto what is known today?
  2. jcsd
  3. Aug 4, 2012 #2
    Brian Greene in THE FABRIC OF THE COSMOS, Chapter 10, says the energy and negative pressure contributed by the Higgs field studied by Guth and Tye was more than 10100
    larger than the value Einstein had chosen...via a cosmological constant.

    But he also says the expansion of the universe during inflation may have been 1030 or 10100 or more....so I suspect you can pick "really,really, big' or 'nobody really knows' as an answer.

    As far as is known, the speed of light has always been it's current value, 'c'.
  4. Aug 4, 2012 #3
    if c was always constant then how it can be consistent with inflation if everything can move only max speed of c?

    wouldnt it violate inflation theory?

    inflation needs a bigger speed than that of light if its ought to be a different theory than that of standard expansion

    ive read that singularity has something to do with this
  5. Aug 4, 2012 #4


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    It's important not to confuse the pattern of expanding distances with ordinary motion. In expansion, nobody gets anywhere. No traveling from here to there. No change in relative positions with one's neighbors. Expansion just means all distances increase by same percentage growth.

    Geometry is dynamic, it can be approximately static and Euclidean over short distances and for short intervals of time but that is not its fundamental nature. Gen Rel. is the theory of geometry and how it changes.

    Distance growth is not limited by the speed of light.

    Even today, the distances to most of the galaxies we can see with a telescope are increasing faster than c. There is no law forbidding that :biggrin: Most of the galaxies we can see are quite far away (i.e. technically "beyond the Hubble radius") and so the distances to them must be growing faster than c. It's a consequence of the Hubble law---the pattern of expansion---or, if you like, by the definition of Hubble distance.
    Last edited: Aug 4, 2012
  6. Aug 4, 2012 #5
    The exact value of the expansion during inflation varies, but it's generally taken to be above 60 ##e##-folds.

    Also, the expansion of the universe (including inflation) increases the distance between sufficiently dense objects that are at rest with respect to the cosmic microwave background, such as galaxies. Special relativity forbids faster-than-light transfer of information, but there is no way to use the expansion of the universe to transfer information. There is no conflict.
  7. Aug 5, 2012 #6
    1 why is unobservable universe invisible(wikipedia doesnt explain this good enough)?

    2 and if observable universe is over 13,75bly then there must be pictures of this area, mostly what i see are pictures concerning age of universe(hubble deep), and maybe confuse this with space distance,
    but who is right regarding volume of observable universe, here its 42bly (but state that they can see up to 47 bly), in wikipedia there someone estimated at 78b ly and even a visualization of 93b ly, whats actual estimated OU?

    3 which one is right?

    and why cant quantum mechanics be compatible with relativity theories? or who is more wrong than another?

    13,75*3,141= 43..

    3 is it a coincidence or has it some meaning?(consider if now observable universe is 43b ly big)

    4 do galaxies move from each other or do they all move away from one point(ala explosion)

    -and if they move away from each other why i heard often theories that m31 and milky way will sometime collide?

    -or does galaxy expands itself?


    5 are they in contradiction? one looks like implosion other looks like explosion

    if to consider: if it imploded then shouldnt be the center be the oldest matter and the more it (as sphere) gets bigger the more newer is it at the age?

    anybody can understand my way of thinking(3d logical), if i accept one thing then i see contradiction with another, are there simple english content other than wikipedia or how did you spent time understanding big bang?

    6 if something expands with over lightspeed, wouldnt it contribute to big rip? and at which speed does "universe" actually expand?

    7 how many km would it be from earth to distance of 13,75b ly(just to better understand bigger distances), ive came to 13006656000000000000000km

    without all these questions answered i cant continue to understand
  8. Aug 5, 2012 #7
    Hey Fat f....lots of questions!!! if you study the following you'll get your answers or be able to calculate them for yourself. [One thing I forgot to post: also see nedwrightcalculator for a popular cosmological calculation tool]

    Some standard dimensions...from Marcus of these forums I believe: [see below for calculation method and explanations]

    ..Here are key excerpts from my notes [many from discussions in these forums] when I was learning this:

    So we use a convention, an agreed upon "metric' [distance measurement] in the FLRW cosmological model.

    I honestly did not understand much of this myself until I came across this illustration....http://en.wikipedia.org/wiki/Metric_expansion_of_space

    Click on the illustrations so you can see them more clearly,,,,,note the red and brown lines and compare with the yellow 'distance'...This pictures the convention utilized.

    and here:

    Some sample calculations via Marcus and instructions how to do them yourself:

    see Post #29


    Also of interest, more complex, I think,

    How is the number of observable galaxies changing right now?
  9. Aug 5, 2012 #8
    1) Light travels at a finite speed. So, when you observe an object that is far away from you, you see what the object looks like when that light was emitted. So, when you look at Mars, you are seeing what it looked like 14 minutes ago, since that's how long it takes light to reach earth from mars. Since the universe has a finite age, light from outside of a certain radius cannot reach us.

    2). It has a radius of 46.5 billion light years. This corresponds to a diameter of 93 billion light years. It's also about 14 billion parsecs.

    You may think that it should be 13.7 billion light years, but this is wrong. Remember that along with growing with time as we can see more light, the observable universe grows with the expansion of the universe. So the radius is larger.

    3) Quantum mechanics is perfectly consistent with relativity. See relativistic quantum field theory.

    4). All galaxies move away from each other (the space in between galaxies expands). No explosion involved. The Andromeda galaxy is so close to ours, that gravity can pull it in towards us and overcome expansion. In cosmological terms, we group all of the galaxies close to us into one 'cluster'.

    No, galaxies do not expand. They are at CMB rest, so the distances in between the galaxies expands. Think of pennies taped onto an expanding balloon.

    5). I can't see your image. But I can tell you that the universe has no center and no edge, like the surface of a sphere.

    6). This is not really a valid question. Expansion is a local phenomena, you can only specify the rate if expansion of the distances in between galaxies, since the universe has no edge or boundary. Since the space in between galaxies is expanding, it looks like the galaxies are all moving away from us with recessional velocities. However, the galaxies actually have very little velocity. Remember, it's space that is expanding. This apparent velocity is given by Hubble's Law, V = H0D. D is the distance to the galaxy, H is Hubble's constant. So, I guess the best way to answer your question is to give you H, which is about 70 mega parsecs per second.
    Last edited: Aug 5, 2012
  10. Aug 6, 2012 #9
    What This means is that distant galaxies on average move away from each other when distances are sufficient for expansion to predominate; The further away, the faster they recede, like in the inflating balloon analogy. 'close in galaxies' move randomly
    and two adjacent galaxies {like the Milky Way and Andromedia} may collide. {These don't model well in the simple inflating balloon analogy.}
  11. Aug 25, 2012 #10
    http://www.astro.ucla.edu/~wright/CMB-MN-03/FRL-28Oct08clean.pdf (last pic)

    #do people on galaxies which are 13bly away see "first galaxies" when they look towards milky way?#

    and do they see that milky way and andromeda are moving away from each other and/or away from observer's direction (like observers on earth see how galaxies are moving away in the distant space(like in picture))


    here it looks like implosion(inside of a sphere), because dark age can be observed around the universe(in each direction)


    and this looks like surface of a sphere model


    is reality in between these models? then it would be like a donut model. if there is no centerpoint which serves as center of universe then it would support what i put into "# #"


    this doesnt help stuff because if universe would be this way then there one could also look back(away from the center):


    was explosion(big bang) this enormous that space expands with 70mpc / s? is inflation responsible for this?


    does somebody understands it trully? i follow scientifical concept to understand something and if i take away one step before another i cant precede, understanding starts from simple and gets more complicated once something is understood but i read stuff where people start from the middle and then its complicated, then i must ask things(puzzle parts) and if they dont contradict each other, i get the picture from answers

    did knowledge came(to cosmologists) from observing mathematical equations which dont contradict each other and was it then applied to understanding(imagination) which then trully understood how universe works/looks like?
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