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Quantity of matter in the universe?

  1. Feb 19, 2015 #1
    https://www.physicsforums.com/threads/is-matter-still-being-created.424456/
    I don't think anyone truly understood what this person was saying.
    He is asking several things.
    Is the big bang done or is it still exploding; the universe is expanding after all?
    How do we know the expanding universe isn't the effect of an on-going explosion?

    Finally, for some reason, I suspect myself and many others have imagined something similar to the following mind-bender. For some reason, I seem to think that the matter within the billions of galaxies that exist today and that stretch through nearly the beginning of time that this represents a fraction of existing matter from the beginning of time or a fraction of the existing energy/particles convertible into matter from the beginning of time. Let try to refine that mind-bender.
    I know the visible matter in the universe is 4.6%, is that percentage growing as time goes by?
    In other words is the universe as a whole done converting non-visible matter into visible matter?
    Or is the percentage of visible matter expected to grow not due to universe processes but due to ongoing big bang processes?

    If you think I am confused, then please tell me everything I need to know so that this matter never confuses me again.

    "Dark Matter - You exist and I will discover all your secrets"
     
  2. jcsd
  3. Feb 19, 2015 #2

    phinds

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    I disagree completely. His question was understood and answered.



    The "Big Bang Theory" is a description of how the universe has expanded from a hot, dense, plasma of unknown extent (but NOT an explosion from a point in space). Yes, the universe is continuing to expand.

    No

    huh?


    It's not expected to grow for ANY reason.

    Then I foresee a Nobel Prize in your future.
     
  4. Feb 20, 2015 #3

    Bandersnatch

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    I'm sorry ericore, but nearly nothing of what you said is consistent with current cosmology.
    Rather than going bit by bit explaining the mistakes, I'd instead recommend clicking on the link in phinds' signature above and reading the article contained therein, as well as the articles linked at the bottom of that page.
     
  5. Feb 20, 2015 #4

    phinds

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    I agree w/ bandersnath. Eric, it appears that you did not pay any attention at all to my first set of answers and you still have a very badly mistaken understanding of cosmology. Perhaps the link in my signature will be of some help to you but even it will not dispel all of your misunderstandings. I suggest that you read more basic cosmology and try to avoid new age woo woo.

    Please realize that we are not trying to give you a hard time here, we are trying to help you understand cosmology but right now you are just stringing together buzz words in ways that have no relationship to reality, so it really would be most helpful if you did more basic reading and then made posts that briefly address one point at a time where you still have questions.
     
  6. Feb 20, 2015 #5
    Hold on just a minute, the big bang happened somewhere from a point, that point is the center of the universe.
    How can you dispute this? The article specifically says there is no center. Well that makes no sense. Also, I already understood perfectly that galaxies farther away are from earth's point of view are travelling faster away.
     
  7. Feb 20, 2015 #6

    phinds

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    Well, welcome to cosmology. "Makes sense" is a concept that is badly overrated in science since both Quantum Mechanics (the very small) and cosmology (the very large) both discuss reality that is outside of our direct human perceptions. There was absolutely zero survival value in understanding things that are outside our perceptions so we evolved without that understanding and yes, both subjects often lead to solid conclusions that seem to defy "common sense" / "intuition".

    Whether you like it or not and whether it "makes sense" to you or not, that is the way it is. Until you are willing to let go of such notions, you will have great difficulty understanding either QM or cosmology.

    Personally, when I first started reading about Quantum Mechanics I was pulling out my hair and screaming cusswords and shouting "THAT CAN'T BE RIGHT !!! " But the universe does not care what we humans think is right, it just does what it does and if you want to understand it, you have to accept that.
     
  8. Feb 20, 2015 #7

    Bandersnatch

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    That's just one of many misconceptions you had had. Keep on reading. All the statements you can find in those articles are supported by observations.

    As for this specific bit - at no point (pardon the pun) in the history of the BB theory did it suggest the universe started from a single point. A universe with a spatially-localised origin of matter would look in a very specific way. For one, you could trace the point of origin by looking at the distribution of galaxies and their velocities. What we see doesn't support such a view.
     
  9. Feb 20, 2015 #8

    Orodruin

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    For the same reason that physicists dispute anything: It does not match with observations.

    Regardless of what you have read in popular descriptions of the Big Bang, it was not an "explosion" in the normal sense of the word. The Big Bang theory is a description of the evolution of the Universe in its very early stages and describes how space and its contents evolved. This involves the expansion of space itself, not simply that distances between objects increased by the objects flying apart.
     
  10. Feb 20, 2015 #9
    Mmmm, thank you bandersnatch for that constructive answer.
    Suprisingly everything in the article except for the center of the universe aspect is reflected in my long explanation.
    Do point out the items which are not because, word for word, it is almost copy/paste.
    I accept that observations do not support the universe having a center; it is not precious to me that the the universe have a center, merely logical from an explosion point of view. How does the big bang theory hold up without a center? And what does the distribution of galaxies and their velocities tell us? Don't say not much. Make it obvious to me how given observations, there can be no center or there likely is no center

    SECOND: SIZE/SHAPE: Yes I know the universe is likely flat, and this is what most believe so I can say this.
    The pennies don't change size. Know that as well.
    what cosmology REALLY says is not that space stretches or expands but rather just simply that gravitationally bound systems keep getting farther away from each other. I have to agree with that since we can't see an edge though you must understood that many almost all publications that the public reads miscommunicate this
    . So that's not my fault.
    FIFTH: COSMOLOGICAL TIME, I understand time not as iminating from the center though I can understand how my explanation may have conveyed this. I understand time simply as the space-time continuum. Beyond that I don't bother with time. I think my knowledge of time needs expanding.

    INFLATION --- In a very early and very tiny fraction of second, just after the singularity, the universe "expanded" in an incredibly massive burst. This is known as INFLATION. Yap I know, and knew it. However, within plank time it is said that dark matter, dark energy and matter were conceived. To me inflation is an effect. You can ask the question not what caused the big bang, but rather what caused the inflation. I say dark energy was conceived the moment the universe came into being, and later dark matter and matter were conceived within plank time. I agree this is speculation, but it is reasonable speculation. How can you talk about dark matter without speculation. I say the understanding of inflation, expanding universe and dark energy at the balloon analogy link is comparable except it doesn't answer the question why the inflation. Dark energy does: because dark energy must have the most minuscule density, it rapidly inflated the whole universe; the path of least resistance, then it slowed down as the universe cooled (quantum mechanics at play); it almost as if the particles that make up dark matter hate each other and want to be the furthest away from each other as possible, so dark matter continued to not only move the galaxies away from each other at increasing speed, but in fact this was an effect of it expanding space. the balloon theory page is a whole different theory, less complete or beautiful in my opinion. It says we don't know if space has any boundaries but we do know galaxies move away from us faster anywhere and even faster if they are further. It says dark energy doesn't expand space, space just exist nothing expanded it because it is stricly against dark energy expanding it. In my explanation dark energy is a a fluid that likes to be the least dense possible. It's speculation either way I say.


    It makes no sense that dark energy pushes galaxies directly.
    It makes more sense, that dark energy stretches space and that galaxies are affected in this way.
    I tackle inflation/accelerated expansion in one punch. They are not separate phenomenon.
     
    Last edited: Feb 20, 2015
  11. Feb 20, 2015 #10
    So then when you design a simulation, how does the universe start if not from a point, circle or any other 2d geometric shape?
    All of a sudden there is stuff everywhere? What happened to plank time, what shape do you give the universe then?
     
  12. Feb 20, 2015 #11

    phinds

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    No reason why it should make sense, since no one has said that it does, unless you have some special meaning of "pushes".

    See, there you go again with "it makes sense". It may make sense to you but it's wrong.

    Yes, they are. If you can show otherwise, once again I predict a Nobel Prize in your future.
     
    Last edited: Feb 20, 2015
  13. Feb 20, 2015 #12

    Bandersnatch

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    I can't respond w/r to the contents of your deleted post.

    As for the question:
    The observation is that galaxies all recede from the observation point (Earth), with velocities increasing linearly with distance V=H0d. The proportionality constant is called the Hubble constant (itself a bit misleading name, but let's not get into that now).
    There are only two ways the observed recession velocities of galaxies can be interpreted: either the Earth is the centre of the universe, or there is no centre and all distances increase with time. The first option needs to be dismissed on the grounds of the Copernican principle. This leaves the other option, which will produce the effect of 'apparent centre' for any and all observers - this can be seen through the application of the balloon analogy by picking any point on its surface and graphing the recession velocities of surrounding points.

    An explosion from a central point would produce non-isotropic spread of velocities, with redshifts depending on which direction you look and lacking the general linear relationship with distance. Specifically, looking at objects lying on an imaginary surface of a sphere centred around the point of origin would produce the Hubble relationship (the farther you look the faster they go) due to geometric properties. But it would not do so for objects lying on the radius of the sphere, as there is no geometric reason for the velocities to vary with distance here.

    But anyway, this would be merely a somewhat weird interpretation of observations if not for the underlying support from General Relativity. It is this theory, whose validity has been checked thoroughly, that first suggested the universe may be in a state of expansion or contraction. The solution of Einstein's field equations provided by Friedman, Lemaitre, Robertson and Walker (see: FLRW metric) describes the evolution of the geometry of the universe - not of matter contained in it suspended in pre-existing space, but of the whole thing, matter, energy and space.

    The observations of Hubble and later the discovery of the Cosmic Microwave Background radiation came afterwards, giving support to the existing mathematical framework. Not the other way around, mind you.

    Conversely, there is no existing solution of the field equations that could produce a universe with matter exploding from a point in a pre-existing space. Such a set-up is impossible according to GR, so it was never proposed.


    One final point, when talking about BB theory keep in mind that it doesn't aim to provide any description of whatever happened at or past the time it stops making sense (the singularity). It says nothing about creation or whether and what came before. It merely describes expansion from an earlier denser state to what we see currently (with all the implications involved, like nucleosynthesis, CMBR, baryon oscillations etc.).
    It's good to draw a line between what is well established (BB) and what is increasingly more speculative (the closer to the singularity you get).
     
  14. Feb 20, 2015 #13

    phinds

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    and to expand just slightly on what bandersnatch has said, there is a very wide-spread item of confusion that I'm sure is causing some of your problems.It is this: The term "big bang" really has two very distinct meanings both of which, sadly, are usually just called "the big bang", which is what leads to a lot of the confusion.

    (1) The Big Bang Singularity --- this is treated by pop science woo woo as though it is a defined thing (an explosion from a point) which is just nonsense. The term "singularity" in this context does not mean "point in space" it means, quite literally, "the place where our models break down and we have no idea what was really going on"

    (2) The Big Bang Theory --- this is the very well studied and verified description of how the universe expanded from a very hot dense plasma into the universe that we live in today. It might have been infinite in extent at that point or it might have been finite but unbounded; we don't know but the current data is trending towards infinite. The only contentious point about this model is whether or not the period of inflation (which is not an established fact, although it is strongly believe to be true) should be included as part of the Big Bang Theory or not. One model is called the "HOT big bang theory" to specifically refer to the period starting after inflation.
     
  15. Feb 20, 2015 #14

    Orodruin

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    The currently dominating cosmology model is that of a Friedmann-Robertson-Walker universe. This describes, using general relativity, a space-time where the space is homogeneous and isotropic. There are three possibilities here, either space is flat, positively curved, or negatively curved. The main point is that it looks the same everywhere, in fact, this is what homogeneous means. Regardless of which point in space you are at, you will see a universe which looks the same. At very early times, the universe had a shape similar to the one it has now, only that the curvature (if the geometry of space is curved) was much smaller. And yes, the Universe was full of "stuff", the same everywhere, as a result of inflation (or whatever initial conditions you are putting on the Universe - what is clear is that it was the same everywhere or we would see much larger deviations today).
     
  16. Feb 20, 2015 #15
    One of the moderators edited my post without leaving a trace.
    Better that way I guess, then by re-appearing with a new pseudonym.
    Thank you for you replies; they are most informative.
    I shall munch on it and several books for now.
     
  17. Feb 20, 2015 #16
    There were some contradictions, lack of precision in my original description of the big bang.
    The following is speculation that I put before you, and I put it before you, to see if you can point to any evidence that would dismiss it.
    Let me be as clear as possible this time.
    What exists is a matter of perspective or where the observer is.
    I like the idea that the outer most observer (the one on top of it all) is correct.
    However, I caution the difference between correct and real.
    There is no correlation necessary between correct and real and this is crucial to understand.

    So, let's step outside the big bang as an observer.
    What you would see (if you had eagle eyes) is a singularity being stretched in 2D.
    From any place you look at the singularity from the outside, it will look like it is being stretched in 2D.
    I'm not speaking to whether the universe is within a another universe; let's keep it simple and focused.
    Here comes the ultimate lottery.
    Let us have an observer inside the singularity directly face an observer outside the singularity; what chance.
    The observer on the inside of the singularity sees 3 dimensions, while the observer on the outside of the singularity sees the singularity being expressed/stretched in 2D, and he only sees it because it is being stretched. Our reality is such that there is space, but in reality there is no space :) bless the outsider.
    Well what's the point of saying that? Very good question.
    The point is we must now refer to space as the effect of a stretched singularity.
    So what about the 3rd dimension? Very good question.
    The 3rd dimension is what makes outer space space is it not?
    It is not! There is nothing more offensive you could say to me; nothing.
    The 3rd dimension is the result of the mass of the content of the universe causing a depression on the space-time continuum.
    Well now you need to be smacked you might think as you just said space doesn't exist and now you talk about space-time continuum.
    Wrong! 2D space exists and the space-time continuum is 2D; lols.
    Now the space-time continuum existed the moment the universe banged; stretched.
    What caused the stretching was both the inception of 3rd dimension and sparse dark matter as opposed to galaxy forming dense dark matter.
    I touch back on this later, specifically on the sparse dark matter.
    I believe the flatness of the universe is a result of the a singularity being stretched in 2D.
    So it makes perfect sense from our view point that the is mostly flat when in fact it is perfectly flat; perfectly.
    There is one major problem with my theory, whether you know it or not, I have already implied our universe is within another universe.
    Putting that aside which is somewhat rude or thoughtful depending on your view point.
    The universe-wide depression along the space-time continuum doesn't stretch the singularity.
    The depression creates space within not out of nothing, but out of mass.
    So 3D space is thanks to everything that is within the universe.
    Indoors, 3D exists because of mass.
    Outside, the observer sees a 2D singularity, but cannot see within it.
    And the reason is because light cannot escape a black hole.
    If light could travel through a black hole and come out of it; it would have effectively seen what was inside.
    Otherwise, a black hole conceals a hidden world.
    So here's a slight mind-bender if you haven't already found the aforementioned mind-blogging:
    Does the 3rd dimension exist?
    .
    ..
    ...
    ....
    .....
    That depends on your point of view.
    It exists, but its existence is dependent on mass. In a generalized way, where there is mass, there is existence.
    The 3rd dimension is not to be confused with 3D space.
    What I am saying is the mass of the universe creates a depression along the space-time continuum which creates the 3rd dimension in our universe.
    Space is actually a combination of the existence of the 3rd dimension and of space expansion.
    Because of this, I personally avoid the word space as much as possible as it encourages entanglement of ideas.
    And cosmic models must as much as possible avoid entanglements.

    Now let's see if the Big Bang and CMB can support the theory.
    According to Big Band and CMB, the universe rapidly expanded within 1 second, then quickly decelerated at an exponential rate, then decelerated at a more linear rate for almost 5 billion years, and then accelerated ever since; this is referring to gravitationally bound systems of course.
    A stretched singularity not only gives you an additional dimension, but increases the distance between galaxies with the effect that wherever you look from the further galaxies always seem to separate faster. The universe stretches in all directions equally (only 2D).
    But what about the galaxies that our a distance along the thickness of the universe?
    This is the tricky part.
    What you have to remember is that 3D space is attached to a 2D membrane; when 2D stretches so too does 3D.
    Mass creates 3rd dimension of space but doesn't control the motion within.
    As I stated earlier, 3D space is a combination of the 3rd dimension (mass) and singularity stretching (space expansion).
    The singularity was in a state of perfection prior to it stretching; a perfect soup.
    Then all of sudden the perfection was broken.
    Prior to this event the universe did not require major action (if any at all) to keep the soup perfect.
    From now on, the singularity will constantly have to tweak itself to stay in balance.
    Sparse dark matter (persistent density) was the first responder.
    In 1 second, the singularity fixed the major imbalance, but minor imbalances would ensure.
    What the singularity essentially did in that first second is pump lots of sparse dark matter into the universe.
    This caused the singularity to stretch rapidly.
    It pumped it as fast as it could.
    As the singularity approached a state of balance, it quickly decelerated the sparse dark matter (SDM) pump.
    But minor imbalances would endure, so the singularity kept pumping SDM but a more linear decelerated speed.
    Up to 5 billion years after the big bang.
    Then the singularity experienced a slight relapse of the initial imbalance.
    So that it would have to accelerate the SDM pump, and continues to do so.
    In other words, there has been no other major event with the singularity since after its first 5 billion years.
    Oh the life of a singularity!

    So is there any observation that could easily dismiss the above mathematically incomplete theory?
     
  18. Feb 20, 2015 #17

    Chronos

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    Keep in mind that every observer in the universe is trapped in an observational prison that is a sphere with a radius the size of the speed of light times the age of the universe. The finite speed of light creates the illusion of a spherical universe with each observer at its center. If you could instantly travel from earth to anywhere in the universe, the CMB from there would appear to be just as distant as it appeared to be from earth at the instant of your departure. You would, of course, see earth as it appeared in the past. It would not look the way it did when you departed until enough time had passed for its light to reach your new location.
     
  19. Feb 20, 2015 #18

    berkeman

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