Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Help with understanding BBT

  1. Sep 26, 2009 #1
    I have a few problems with the big bang theory that I just don't understand as of yet.
    • Matter and energy can never be created nor destroyed, or so they say. So then how did the BBT pull off this seemingly physics defying act of creation?
    • There appears to be very old mature high density galaxies only 750 million years after the big bang intermingling with the younger galaxies.
    • We've also found galaxies not far from our own that are on the order of a few hundred million years old to one billion years old.
    • There doesn't appear to be any convergent point in space that all matter has come from, everywhere we look we see space getting equally larger the further out in every direction as if we were in the dead center of the universe.
    • The universe appears to get "older" the more powerful our telescopes get, we keep finding galaxies further out near the so called beginning and have pushed the age of the universe up
    • Inconsistencies with using redshift as an indicator of distance, I haven't heard any explanations for this as of yet.
    • Do we really see space itself expanding or is the entire theory based on the movement of galaxies and then the extrapolation of that movement backwards in time? If we can't point to an actual patch of space itself and show it expanding, then how can we conclude that space itself is expanding?
    • Why if the BBT is so obviously true, do we need to invent invisible things that are not observed? We claim we have observed dark matter and all, but we still haven't shown it or know what it is or how it works. There are other competing theories that explain away this magical form of matter with more accuracy and without the need to invent magical invisible substances that defy physics.
    • Why are not all galaxies moving or receding away from each other as if 'expanded' from a singularity of dense hot matter? It appears that galaxies are following a more haphazard route across the cosmos. There doesn't appear to be any discernible pattern of expansion. Some coming towards, some moving away and large patch's heading towards a point in the sky as if being tugged by something larger beyond the universe while everything else is not. To explain all this we invent magical invisible unobserved forces.
    • What mechanism was at play that has been observed that would allow the early universe to expand at an exponential rate that defies the laws of physics?
    • I've also noticed that galaxies tend to move at different rates of speed compared to one another, which seems counter-intuitive of a magical singularity expanded outwards in space. Did this singularity defy physics and not expand space in a uniform fashion?
    • Black holes are considered singularities and yet we say nothing can ever escape from them. If this is the case, then was the BBT singularity a magical singularity?
    • There exists large voids in the CMB when there shouldn't be with current BBT theory as well as larger than accountable voids in surrounding space between galactic super clusters.

    That's all for now. Just a few problems I have been having with the BBT recently.
  2. jcsd
  3. Sep 26, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    First of all, I'd suggest you not use such loaded words in your questions if you actually want to promote a constructive dialogue.

    A few of the points:

    Energy is always conserved, but matter can certainly be created. From a Newtonian perspective, the gravitational attractive energy of the universe exactly balances with the positive kinetic energy, keeping the total energy of the universe to be exactly 0.

    There certainly is no convergent point in space where all matter has come from, as the universe has no centre. We expect to see galaxies flying away from us, and this is what every point in the universe expects to see.

    The age of the universe can be inferred from the Hubble constant, and the matter/energy content of the universe. As far as I know, all astrophysical objects that have been found are consistent with this age.

    There are, as far as I know, no alternative theories right now that can explain observations such as the bullet cluster, without dark matter. Dark matter and dark energy certainly do not defy physics - they are very easily incorporated into the equations of cosmology.

    Exponential expansion certainly does not defy the laws of physics.

    Black holes are certainly not considered singularities, only the singularity at the centre of a black hole is considered a singularity. But really, we do not yet have a sensible enough theory of quantum gravity to discuss what happened at the moment of the big bang.

    Really? Does this not look like a discernible pattern? http://www.valdostamuseum.org/hamsmith/MRRhubble.gif [Broken]
    Last edited by a moderator: May 4, 2017
  4. Sep 26, 2009 #3
    is your post a question or a statement of intent?
  5. Sep 26, 2009 #4
    All I'm trying to do is raise a few questions and problems I have with the big bang theory. I'm not a creationist or religious, just a curious person who see's a few problems.

    How is matter created then and can we confirm the creation of matter from nothing in a controlled setting?

    If the universe was born from a singularity then how can it have no center? How does something expand from a singular point in space without a central point of expansion? Why do we see galaxies not just flying away from but also towards us, each other, and in haphazard paths that don't appear to be expanding from anything?

    And yet we see various galaxies of various ages intermixed. I've also been reading about problems with redshifts. Quasars with obvious bridges to galaxies. I've heard that this is just chance alignment and that not all quasars are connected to galaxies. Only problem I have with that is that chance shouldn't account for every single alignment showing an obvious bridge to a quasar when it's in close proximity to a galaxy. Chance just doesn't work like that as far as I'm concerned.

    I'm sure I could mathematically incorporate all sorts of unobserved things as well, yet we don't know what dark matter/energy is. We can't create it, we can't see it, we can't experiment on it. For all intents and purposes it appears that dark matter/energy is nothing more than a mathematical construct to make actual observations fit with the current theories.

    I can agree with that statement so long as the expansion is actually coming from something, which it does not appear to be doing so. I mean, what are we expanding from and into? You said there is no central singularity that we are expanding from, and yet the BBT says all matter and energy came from this singularity. Were the laws of physics somehow different back then? Can we demonstrate that the laws of physics can change on a whim?

    You knew what I meant. Regardless, we don't even have a grasp on the theory to explain where this singularity came from or why it suddenly expanded. QG isn't going to tell us that. How can such an immensely large hot dense mass singularity escape it's own gravitational tug? Light can't do it, but somehow an entire universe can, that sounds like a physics defying act to me.

    When I look at maps of galaxies in the universe, I don't see any actual pattern suggesting expansion from something. If space itself is expanding, then how come we can't show it doing so or have a verifiable mechanism for it?


    A little of both I suppose. I'm genuinely curious about the points I raised, but I'm also starting to realize that the potential problems with the theory show an either larger universe with a different mechanism for the birth of the universe or an infinite universe with a finite amount of matter. I personally think an infinite universe is the more simplest answer than a big bang that came from something which raises the question of where that came from and so on.
    Last edited by a moderator: May 4, 2017
  6. Sep 26, 2009 #5


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    I won't go through your entire list, but have a comment on this first item. The Big Bang Theory makes no claim about conditions before the Big Bang. There is no claim that energy was suddenly created out of nothing, merely that all energy at one instant in time was located at the same point in space.

    That may be a simplification of the theory, but that's the gist of it.
  7. Sep 26, 2009 #6
    1 You are misinformed.
    Singularity IS NOT a point.
    In fact, if (which is very likely) our universe is infinite in space, it was ALWAYS infinite in space. 'Expanding from a sigle point' is an over-over-simplified junk you can read in some popular articles.

    2 WRONG. The only galaxy which is approaching us I know is Andromeda. There are other few galaxies. All other galaxies are running away from us.
  8. Sep 26, 2009 #7
    1 Map shows POSITIONS, not velocities! What did you expect to see looking at the map? When space is expanding or contracting on the map you will see the same - galaxies spread evenly everywhere (with some voids and clouds)

    2 Red shift is a verifiable mechanism. It is known long time ago, Hubble's discovery.
  9. Sep 26, 2009 #8


    User Avatar
    Staff Emeritus
    Science Advisor

    You seem to be hung up on a point that the 'big bang theory' requires an explosion and an expansion from a central point in the universe. This is not true. All that the big bang says is that as you go further into the past, the universe was a lot hotter and denser than it is today. If you extrapolate back further you will find a singularity, however, most physicists do not believe that such a singularity physically exists, but instead that this is simply a warning that our model does not cover that initial time. This is quite a reasonable thing to think: as the universe gets smaller and smaller going back in time, there will come a point when quantum effects become important. However, since we don't have a theory of quantum gravity yet, our model cannot feasibly cover this point.
  10. Sep 27, 2009 #9
    It is certainly looking to us as it all came from one point, if you trace back mass energy distribution throughout time. But what you should keep in mind is that even time was squeezed into a point, with no cause leading to consequence, and no theory can give any predictions what was happening before BB, or what triggered it. (Note that even our language fails here, verbs "to happen", and "to trigger" have no meaning without time)
    We must accept that our logical concepts are based on our everyday experience, and Big Bang is not part of that.
    To search for answers to questions like "When was the time for time to begin?", we must resort to concepts that are impossible to picture in our minds, like imaginary time.
    So for now Big Bang's theory arguments can be described as "It walks like a duck, it quacks as a duck - so it is a duck". Is it a duck? What kind of duck? It remains to be seen.
  11. Sep 27, 2009 #10


    User Avatar
    Science Advisor

  12. Sep 27, 2009 #11
    I understand the big bang makes no real claim to where matter and energy came from, but it does propose that it all existed as a hot dense singularity, but in order for this singularity to exist with all the current matter in the universe, it had to be one huge singularity, bigger than any observable claimed black hole.

    The problem I have with that is that we say nothing, not even light can escape a singularity, so then how does one lay claim that the universe can come from one? Why do we have to mathematically invent an unobserved force that can not be tested for or recreated and proved to explain the universe's current size? I would hazard a guess that anything that needs to be invented that hasn't been seen or observed nor can be tested for to make a theory work should be enough to falsify the theory itself. It's like claiming god is real and then not showing the work.

    Everything I've read about singularities liken it to an infinite hot dense point. How is it that everything I've read on the theory say this, but now you say this is not true? Are all those thing's I'm reading lying?

    Not only is redshift a verifiable mechanism, but it's also a variable mechanism and has been demonstrated to be so in lab settings. If redshift is indeed variable, which it does seem to be so, then how can it be used as an accurate measure of anything across vast distances? Even Hubble had mentioned something against using redshift.

    I'm hung up on it because of what a defined singularity is and that we say space is expanding, one plus one equals two. If the universe is not expanding from what we say the universe had came from, then what is is expanding from or into? The further out we look with our telescopes we never see the universe getting smaller, sparser or denser. The only hot spot around is the CMB, but there are other theories that have accurate predictions for the CMB as well. If the singularity didn't exist then where did everything come from?

    I'm a little upset that only a few of my points have gotten somewhat answered. Whenever I read something new, it seems more like the big bang didn't happen. There are other theories out there (thanks to the internet because I probably would have never heard of them otherwise) that explain what we see without inventing fifteen different untestable and invisible things required for the current model to work. Whatever happened to occam's razor?

    I just don't get it at all.
  13. Sep 27, 2009 #12


    User Avatar
    Staff Emeritus
    Science Advisor

    Like I said above, you shouldn't take the notion of the initial singularity too seriously. You should just know that the big bang theory says, roughly, that the universe was once in a very hot and dense state, and has expanded from that.

    Again, no scientist says that 'the universe came from a singularity' (whatever that even means). Please read the link Chalnoth gave above: it should help clear some things up.

    To be fair, a lot of your points are repeated, and many of them come back to your misunderstanding of standard cosmology.

    What '15 untestable and invisible things' does the standard model of cosmology employ? As for Occam's razor, it only applies when two theories make the same predictions; then one can say that the simplest is the best. I don't know of any current theory rivalling the standard model that makes exactly the same predictions, and accounts for the observations in an equivalent way, without making some of the assumptions (like dark matter).
  14. Sep 27, 2009 #13
    True, there is no one theory, but there are a bunch of different theories that explain certain aspects without the invention of invisible unseen things. A simpler explanation of redshift exists and has been demonstrated in the lab whereas the space is expanding explanation hasn't been demonstrated. That strangely sounds like two opposing theories with one having a simpler solution that has been accounted for while the other shows no such accountability. There even exists observed evidences of such out in the cosmos with quasar/galaxy pairs with obvious bridges, chance doesn't allow for bridges to exist by random alignment with every single quasar close to a galaxy nor to appear in front of a galaxy. I've also been reading some thing's on the electric universe which I just found out about yesterday that makes more sense on how the universe works without the invisible unseen inventions of the big bang, it even allows for the filament like formations that occur across the universe and we know that this is how plasmas behave in the lab. Whereas in order to explain these structures we have to invent dark matter which we can never play with in the lab. Again, another more simpler, observed, and experimented explanation without invention of unseen invisible untestable things.

    I understand now that BBT is just describing how the universe works, but with other theories that describe the same of how the universe works with testable observations, how can we still lay claim to something so complex that requires invisible untestable things to work with what we see?
  15. Sep 27, 2009 #14


    User Avatar
    Staff Emeritus
    Science Advisor

    You should really read the link that is given above.

    As for other theories: it seems like you're picking and choosing certain predictions that each model makes. The beauty of big bang cosmology is the number of pieces of evidence that support it (which are also given in the link above). To date, no other theory (that I've seen) agrees with the same number of pieces of evidence.
  16. Sep 27, 2009 #15
    Existence can be started from nothing

    Two methods.

    1) ET = 0 = (+E) + (-E) = (Σ+mc2) + (ΣU) = (Σ+mc2) + (Σ-GMm/r) = 0 = ET
    ( U has a - value )

    2) ET = 0 = (+E) + (-E) = (Σ+mc2) + (Σ-Mc2) + (ΣU) = 0 = ET
    ( U has a ± value )

    Existence can be started from nothing.

    Good Lucks!
    Last edited: Sep 27, 2009
  17. Sep 27, 2009 #16


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    (bold added)

    "the electric universe" is not science, and contains no scientific theories.

    In fact, it's intellectually http://dealingwithcreationisminastronomy.blogspot.com/2009/08/electric-universe-creationism.html" [Broken] (be sure to read the rest of Tom's 2009 blog entries).

    To take just one example: "There is no way that a measurement taken at only one end of a transmission channel can reveal changes that have occurred farther up the channel." That's from the horse's very own mouth ... which means that astronomy cannot inform us of anything unless and until we can visit the source of the photons we detect (the author uses this to refer to neutrinos, but what's good for the neutrino goose is good for the photon gander).

    Reading widely is good, as is having an open mind; however, if your mind is so open your brain falls out ...
    Last edited by a moderator: May 4, 2017
  18. Sep 27, 2009 #17
    You heard that black holes contain singularities inside.
    Then you heard that light cant escape from black hole
    So now when you think about the BB singularity, you conclude that light cant escape from it - WRONG

    Light cant escape from black holes, this is true, but it is a property of the Black Holes only, and more precisely, it is a property of their 'surfaces' called Event Horizons. Singularities can be visible in some cases - for the observers inside rotating black holes, for example.
  19. Sep 27, 2009 #18
    Singularity IS NOT a black hole!

    Finally, if our universe in infinite, it was always infinite, hence the initial singularity was infinite in size. Singularity, as I said before, in not always a point.
  20. Sep 28, 2009 #19
    Your smearing the meaning of 'singlularity' left, right and centre...
  21. Sep 28, 2009 #20
    Re: Existence can be started from nothing

    What in the world does that all mean?
  22. Sep 28, 2009 #21


    User Avatar
    Science Advisor

    Re: Existence can be started from nothing

    With zero total energy, you can still have lots of stuff. Basically the positive energy in matter fields is offset by negative energy in the gravitational field.
  23. Sep 28, 2009 #22
    Thank you Chalnoth.
  24. Sep 28, 2009 #23
    Re: Existence can be started from nothing

    I’m sorry, I can’t English well.
    Please, understand my insufficient explanation!

    It’s mean that our universe can be starting at zero energy by physically.

    So, universe need not started from the black hole shape of that all matter of present was concentrated at one point.
  25. Sep 28, 2009 #24


    User Avatar
    Homework Helper

  26. Sep 29, 2009 #25
    err.. thanks.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook