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A Theory

  1. Apr 14, 2008 #1
    First of all, I'd like to say that I am 16 years old and have received no formal training or education in the field of cosmology or astrophysics. All the information I obtain is through this fine forum and books I've read, so forgive me if this is a ridiculous thought.

    I was thinking about the origin and possible fate of the universe the other day and came up with this idea. I've heard that some people theorize that black holes can be compared to a wormhole, with the difference being a black hole could possible be stable as opposed to actual wormholes. The theory goes onto state that any information unlucky enough to fall into the gravitational field of a black hole, could possibly be ejected from a white hole in another dimension of the universe. I made the following idea based on the assumption that this is a valid way of thinking. I imagined the birth of the universe as a point in the middle of an empty sphere. At the point of the big bang, everything started moving away from each other in all directions. I thought of the possibility of the objects reaching the "edge" of the sphere and bouncing off, heading back toward the point at which it was created. It is my understanding that the universe would become more and more dense as it condensed back to it's origin. That said, it is also my understanding that a large amount of gravitational pull would come as a result near the origin. I theorize that based on the aforementioned assumptions, that as the matter reaches the origin, a black hole or something similar is there to "swallow" the matter so to speak. If white holes eject matter that a black hole has captured, could it be possible that the matter is ejected in a nearby sphere (in a situation similar to the bubble theory [I think it is called]), and the process could essentially repeat itself.

    If that is the case, then would it be logical to say that the known universe is essentially finite, but the universe overall is infinite as it is recycled.

    As I said, this may be a ridiculous theory, but the idea just came to me based on what I've heard. I've read a bit on the universe being recycled but I'm not sure how valid it is.

    In conclusion, I was simply wondering if any of this was probable or if it was a ridiculous thought. Thanks in advance.
     
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  3. Apr 14, 2008 #2

    Nabeshin

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    Interesting that you thought of this, but I have a couple things to point out. First off, when people theorize about white holes, it is worthy to note that it is also a possibility that they would exist in completely separate universes (as we have never observed one). Also, I don't know about your idea of the big bang. It is very widely accepted that the big bang was the beginning of space itself; that it's expansion was the expansion of space itself. According to this, at least, the thought of a finite sphere containing expansion of the universe is impossible. Another note, even if the universe was expanding in an enclosed "sphere" there would be a serious problem with running into it. The reason things bounce in the first place is because of mutual repulsion of electrons when they get too close to each other. Something like a barrier of the UNIVERSE would surely behave nothing like this, so what would happen when matter collided with this boundary is entirely in the air.

    Additionally, this would put us at a very young stage in our universe's development (or just mean this hypothetical sphere is very large). Because we seem to be observing overwhelming redshifts from distant galaxies, it appears none have yet "bounced back" from the outer boundary.

    In terms of long term dynamics of such a system, the universe would ultimately degrade. While not a whole heck of a lot is known (or even speculated) about white holes, we know a bit about their black cousins. As mass approaches the event horizon in the accretion disk, it heats up and releases x-rays. Now, assuming this cycle to be infinite, the entirety of matter in the universe should be converted into radiation in this matter. The ultimate fate, indeed is not so good. Although, I suppose it's no more morbid than what current cosmological models are predicting :)
     
  4. Apr 15, 2008 #3
    this reply was totally exciting to read. :)
    you should both watch (if you havent already) the history channel's, the universe series. i have it on on-demand and i absolutely lose myself in it. i think i understood that physicists think that based on current mathematic models, the only thing that makes sense about the expansion of the universe, is its simultaneous collapse due to dark energy?????
     
  5. Apr 15, 2008 #4
    Thank you for your reply. I have a few other questions.

    If we suppose that the creation of the universe (and thus, the hypothetical sphere I'm mentioning) where was all the matter needed to create a big bang, located?
    Branching for the previous question, I feel there had to essentially be space before a big bang occured and that the expansion of space simply means that everything located in it is moving away from one another. Is that illogical?
    And lastly, how exactly would a "Big Crunch" occur?
     
  6. Apr 15, 2008 #5

    Nabeshin

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    I'm going to be careful here when I attempt to answer your questions.

    First off, when you "feel" there has to be space before the big bang, I'm not sure how to contest this. On one hand, this is a VERY common misconception among the public: that something existed before the big bang and the universe is merely expanding "into" it. What we currently believe is that the expansion of the universe is the expansion of space itself, somewhat like the stretching of a beach volley ball as you blow it up. Now, seeing as you are suggesting a theory here, I'm not sure if you already know this or are merely suggesting an alternate hypothesis. If you are suggesting an alternate hypothesis, then like you say it raises the problem of where did this containing sphere come from. Of course, we still don't know where the big bang came from!
    Now, this is my personal feelings, but I'm not so sure if we're ever going to find out where the big bang came from. Theories get so colorful attempting to explain the origin of the universe, that they have almost no basis on scientific fact. After all, science, as we know it, does not (or need not) apply outside of our own universe. One of the theories I'm aware of suggests that branes in a higher dimension (essentially planes) are all stacked, somewhat parallel, and have fluctuations in their smoothness. Occasionally, two branes will collide and from this a universe is born. Now, how an idea this obscure comes to be out of string theory I don't know, but I can't think of any way to test this hypothesis. Furthermore, it merely shifts the blame. Where did the branes come from? The answer is they've always been there, which is hardly more satisfying than simply saying the big bang was the beginning of space and time.

    Before I attempt to field your question about the big crunch, which context do you mean it in? In the context of your spherically enclosed universe, or in that of modern cosmological models?
     
  7. Apr 15, 2008 #6
    First of all, I'd like to clarify that I know what is currently accepted as the expansion of the universe, being the expansion of space itself, and yes, I'm posing an alternate hypothesis.

    I've often read that it would be pointless as to ask what "was" before the big bang, as since spacetime didn't exist yet, there was nothing there anyway (or something along those lines) Regardless, doesn't the law of energy conservation state that energy can be neither created nor destroyed? If that is so, then doesn't that mean the universe couldn't have spawned from nothingness? I'm not a religious person, but if this is valid, I think I could conclude that an omnipotent being had to exist in order for it to be created. Some may pose the question that the omnipotent being had to come from somewhere, but that had to be invalid, for if it had the ability to create the laws of science, it must be able to violate or change them as well. I agree with you that we will probably never know how the universe was created, but my curiosity just won't go away :P

    I should also clarify that I was asking how you yourself would explain a big crunch based on what you know.
     
  8. Apr 15, 2008 #7

    Nabeshin

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    Okay. The law of energy conservation doesn't exactly say that energy can be neither created nor destroyed. We have to remember that mass and energy are equivalent via e=mc^2. Therefore, I believe, it is thought that there was simply an extremely large quantity of energy at the singularity of the big bang, which was converted into matter by understood means of physics. Also, I'm less clear on this point but applying laws such as this back to the moment of the big bang is treading on very very shaky ground. Therefore, I'm not willing to say this statement is correct because I (nor anyone else, I believe) can extrapolate that far.

    As far as the big crunch is concerned, recently it seems to have fallen out of favor due to the acceleration of the expansion of the universe via some mysterious dark energy. But the theory goes something like this. Gravity acts between any two massive objects and is always an attractive force. Therefore, when there is mass in the universe it will attract all the other mass in the universe. The big crunch theory states that if the mass density of the universe is high enough, gravity will "overcome" the expansion of the universe and collapse the entire thing back into a singularity. What I mean by overcoming is that matter will not be moving away from other matter fast enough via the initial expansion to overcome the gravitational attraction. This type of scenario led many to postulate that we are in an infinite series of cyclical universes which are born, grow, collapse, and die, only to be reborn again. Of course, it seems, however that no information is translated from one universe to the next, so again, I find this prediction to be metaphysics.
     
  9. Apr 15, 2008 #8
    Thanks again for your reply. I think I understand it better now.
     
  10. Apr 20, 2008 #9
    I am by no means an expert in string theory, but as far as I understand it, branes are simply strings with vast amounts of energy (and are able to increase in size accordingly).

    Strings are confined to certain branes based on whether of not the strings themselves are open ended or closed loops (open strings are thought of as being attached to a brane by one end and closed loops are free to escape from the brane).

    As far as I know, the possibility of branes simply comes out of the mathematics of string theory, so I am basically in agreement with everything else you have said. Today, these hypotheses are (largely*) untestable and do indeed shift the 'blame' to a big bang which was the beginning of a much larger multiverse.

    * An experiment at the LHC in 2012 will test the hypothesis of gravitons (being closed loop strings) being able to leave our brane (something which would account for gravity's sizable strength difference when compared to the other known interactions). Apparently by observing certain collisions the escape of the graviton to higher dimensional space would be inferred by it's absence in the detector.


    Sorry if I'm rambling or talking about things of which you are already well aware; this is the kind of discussion that fascinates me and I couldn't help but add something.
     
  11. Apr 20, 2008 #10

    Nabeshin

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    I agree that string theory is simply fascinating due to its elegant simplicity.

    In regards to the experiment you mention, I would like to see exactly what they are looking for and how they can infer that something has left our three (four) dimensions. Also, this probably belongs in another topic now but I don't feel like making one: I think I remember reading something about how string theory is, directly at least, completely untestable. Because the strings are on the order of the planck length, it literally is impossible to ever probe down to that length and see if they actually exist. Thoughts?
     
  12. Apr 21, 2008 #11
    I remember seeing in the NOVA TV version of Brian Greene's The Elegant Universe that they gave the scale of a string as being the size of a typical tree on earth if the entire solar system were to represent an atom. So directly, yes, it would seem that string theory is untestable (which is why absences and not observations of expected particles may be what is sought after in the case of higher dimensions).

    My (primitive) guess is that in the observed collisions, misbalances in the equations of conservation of energy and/or momentum would indicate the absence of a particle which one would expect to observe in the detector.

    Here's a link to the website of the ATLAS detector at the LHC, but it doesn't seem to be a very good source of information: h ttp://atlas.ch/index.html

    There is also a Wikipedia page on the ATLAS experiment, but once again the information given is fairly non-specific.
     
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