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Question about dark matter gravity and the expanding universe.

  1. Jun 29, 2011 #1
    My question/thought is this...

    We know gravity is related to matter, could dark matter have "anti-gravity"

    Just like magnets have different polarities, one to attract and one to repel, could gravity have similar properties that we are unable to identify, perhaps related to types of matter or energy that we cannot identify, yet?

    This is a question I thought of while pondering the mysteries of the expanding universe and I thought that gravity is the only force that can affect things on such a huge scale, but since it is expanding and not contracting I thought maybe there could be a type of gravity with an opposite "charge".

    I also wondered if gravity could be the contributor so I will also ask could there have been other big bangs all throughout an infinite universe and our observable universe is being pulled by those other hyperclusters of galaxies, I don't know what else to call the sum of matter created by a big bang, and they are too far away for their light to reach us?

    And if the gravity from something is reaching another object does that mean its light should reach it as well?
    Meaning that gravity works at the speed of light?
  2. jcsd
  3. Jun 29, 2011 #2


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    That would defeat the whole purpose that dark matter is supposed to serve. Dark matter provides the extra gravity needed to explain the rotation curves of galaxies. If it had anti-gravity it would have exactly the opposite effect.
  4. Jun 29, 2011 #3
    So you are asking if gravity has currently undetectable effects on currently undetectable matter? I dont think you will get very far with that vein of questioning so you may want to reconstruct your question.

    What do you mean by this? Remember that gravity is one of the weaker electromagnetic forces, gravity also doesnt have a "charge". While I understand what you mean, essentially repellant, gravity in GR is the curvature in space time and there is a clear distinction between gravity in GR and newtonian gravity.

    This can be ruled out by current observations and CMB uniformity. Essentially CMB is so uniform it is likely this is not the case, the idea of an infinite space to expand into is one explored in a Milne topological Universe and one that has a lot of observational evidence against it.

    Newtonian gravity assumes instantaneous gravitational "force", this can be seen using newtonian mechanics on calculations of solar orbits - where without instantaneous propogation orbital mechanics fail. However in GR gravity is not a "force", in GR, the curvature in space/time created by gravity propogates at the speed of light. These may seem to contradict each other but they do not, in GR, the gravitational center is not central to the center of mass but takes into account velocity and position. Essentially the compounded result is that the propogation of gravity at light speed is almost cancelled resulting in the same results as newtonian mechanics.

    Anyone that can expand on this would be greatly appreciated.
  5. Jun 29, 2011 #4
    I think the universe expands increasingly fast becouse on the outside of our universe is less matter, so time moves faster there.

    And i think in contrary to popular thought that time and space and matter begun at a big bang, only time and matter begun at the big bang, space was already there.
    Before the big bang, time went infinetely fast becouse there was no matter.
    I see matter as a disturbance in space. If you think about it, what we percieve as 'nothing' has more complexity in it than matter. All kinds of waves go through it and once it hits matter the waves materialize like we see in the dual slit experiments.
    Its like the 'emtyness' part of the universe is 1 membrane and the matter side of the universe is another and they bumped into eachother in a higher dimension. The only things the two share is energy and time.. The time in the one domain of waves moves at a constant speed of light, the time in the domain of matter is constant.

    I think dark matter is a calculating error. Sceintists wanted to account for 'missing matter'. There is no missing matter. I saw once on discovery channel that it was a calculating error and after that never more. But i believe that is the truth.

    I am sure many won't agree with me but this is my view.
    Last edited: Jun 29, 2011
  6. Jun 29, 2011 #5
    Many of the points you made are without foundation (at least not a referenced one you have provided) - in fact some of these statements are a little ridiculous.

    If you can strengthen the points you made with accompanyting scientific papers - and articulate your points more clearly and concisely, making a clear distinction between ideas then you will recieve better feedback. Essentially you have just flown in the face of accepted science without any credible argument, "I believe" does not count unfortunately.

    Please do not take this as harsh criticism, as if you approach the site in the correct way there are many things you can learn and great discussions to be had. However you must consider the PF rules and promotion of personal theory is a breach of these.

  7. Jun 29, 2011 #6


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    You should allow your views to be shaped by evidence, rather than prejudice. Ignoring empirical evidence in favor of preconceived ideas about nature is dangerous, and in my opinion, a terrible waste of a functioning intellect.
  8. Jun 29, 2011 #7
    Thank you for your oppinion on my views.
    Although my words seem like logic to me it didn't occur to me people like you want me to back up my words by other peoples sceintific papers. Or maybe you want me to make a sceintific paper for you?
    If sceintists thought the same, nothing new would ever be discovered or developed.
    I have done a great deal of thought about the subject and have done my reseach.
    On the same note i haven't seen any link to sceintific papers here yet. But then i am here since yesterday.
    Also i haven't seen many TV programs or youtube movies refering to sceintific papers.
    In the future i will expain more clearly why i think the way i think it.
    But i don't obey the rule 'shut up if you don't think the same as i'.

    Einsteins theory of relativity states that time goes slower on places where there is more matter (energy). On the outside of the universe is less matter so time goes faster there.
    Last edited: Jun 29, 2011
  9. Jun 29, 2011 #8


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    There is no such rule, the way that science works is that people learn the subject first (this way they can demonstrate a good enough understanding of the topic for people to take them seriously as well as allowing them to come up with good hypotheses), develop a hypothesis about some observed phenomenon, test their hypothesis with experiments, publish the data.

    It is not enough to misunderstand the current science, say "I think" and then complain when people point out your flaws.

    P.S This site is packed full of links to scientific papers. Many of us here are scientists. I would advise you to check your facts before making claims, in all walks of life.
  10. Jun 29, 2011 #9
    Ok i will not use the words 'I believe' or 'I think'.
    And i will refer more to established sceince.

    In all walks of life huh?
    Where did you get evidence that i don't do that already in other walks of life.?
    It must be hard to have a conversation if you have to check your facts every sentence and while you are double checking it, double check it elsewhere too (you said all walks of life).

    Point taken: Will refer more to established sceince.
    Point rejected: What i said is just a little ridiculous becouse i didn't refer to established sceince / papers.

    But this thread isn't about me. go back to topic please.
  11. Jun 29, 2011 #10


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    Yes in all walks of life it is best to have empirical evidence before making a decision, it is definitely best to say something only when you know there is evidence for it.

    What you said was not just ridiculous because you did not show any evidence to support your non-mainstream ideas but because much of it conflicts with what has already been established by mainstream physics.

    Science does not work by someone coming up with random ideas off of the top of their heads (even if their ideas do have internal consistency), it works off of what we already have established.

    What does "outside of the universe" even mean? Current understanding in physics is that there is no such thing.

    Time and space are one (hence "spacetime"), you cannot have one without the other. Physics has nothing to say about what occurred "before" the big bang or even if that makes any sense. If you are going to suggest something you are going to need evidence for it.

    Time does not "go" at all.

    This doesn't even make much sense. If you are proposing the existence of other universes you are going to need evidence that such things even exist before trying to discuss their properties.

    To back up that statement you need evidence from peer-reviewed literature. It is not enough to claim something without evidence.
    Last edited: Jun 29, 2011
  12. Jun 29, 2011 #11


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    You have made several assertions that have no basis in scientific fact in a science forum. Seriously...you don't see the issue?
  13. Jun 29, 2011 #12
    As far as i know there is evidence. And i don't see anyone refering to papers proving the opposite. So its a bit silly people say how to do it and at the same time don't do it themselves. This is based on hard evidence in this thread.

    Well, i am against establishment. I am all for evolving. Humans are evolving creatures not established and so should be their idears.

    Yes it does. All evolution start with random events. Evolution of humans and other life forms by random changes to the DNA, evolution of universes and stars by random pull of matter into stars and planets and even sceince have evolved from newton to einstein by random brainwaves and observations and will keep evolving. The events that don't work are rejected but that doesn't mean they should not have happened.
    But noone here tells me exactly why it cannot be, refering to papers. But rather say i shouldn't have the idear at all and attack it on the words i am using and the fact that it isn't supported by established papers.
    It seems there are two types of people, those who want to discover and evolve and those that want to keep the established established.

    Please go back to topic.
  14. Jun 29, 2011 #13


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    I refer you to the burden of proof, specifically the fact that the onus is on the claimant.

    Now you are being very, very ignorant. Everything around you is the product of the scientific method, it works by intelligent people taking what we know and pushing it further. This is done through research, observation, hypothesis, testing, conclusion. It is not accomplished by ignoring what scientists already have to say and spouting inconsistent, illogical ideas that go against mainstream science.

    Cosmological development and biological evolution are nothing to do with the gradual improvement in our understanding of the world around us. As I have said the scientific method is based on intelligent exploration of the world through well performed, methodical experimentation. Not random musings or "brain waves", if you were trying to "discover" you would have read physics books on the subject and proposed ways of testing your hypothesis.

    Some reading for you;

    Last edited: Jun 29, 2011
  15. Jun 29, 2011 #14


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    My problem with this (and maybe others), aside from lacking evidence to back up the claims, is that you can't just put together physics terms from different frameworks and hope to come up with something coherent. If you can bring mathematics to the table then you can be taken more seriously. Statements like "The time in the one domain of waves moves at a constant speed of light" can't be plucked from thin air - there has to be some mathematical formulation of it; there is a reason why mathematics is the language of physics. Otherwise, such statements will come off as absurd as many have pointed out.
  16. Jun 29, 2011 #15


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    Please see the following FAQ: http://www.astro.ucla.edu/~wright/cosmology_faq.html#XIN , "What is the Universe expanding into?" There is no "outside."

    The rest of this material is overly speculative.

    One of the main goals of PF is to help students learn the current status of physics as practiced by the scientific community; accordingly, Physicsforums.com strives to maintain high standards of academic integrity. There are many open questions in physics, and we welcome discussion on those subjects provided the discussion remains intellectually sound. However, it is against our posting guidelines to discuss new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current professional scientific discussion.

    The following are some online forums that specialize in discussing independent research, highly speculative ideas, or ideas that run counter to mainstream science:

    http://groups.google.com/group/sci.physics.research -- Read this first: http://math.ucr.edu/home/baez/spr.html
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  17. Jul 1, 2011 #16


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    If you intended to ask question about expanding universe then it seems that you have mixed up dark matter and dark energy.
    So if you would ask if dark energy could have "anti-gravity" then the answer would be that dark energy basically is "anti-gravity".
  18. Jul 1, 2011 #17


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    That's not so. At least until you have tried to model dark matter this way and proved that this gives poor match for actual observations.

    The thing is that it depends how you distribute sources of anti-gravity. If you place source of gravity and source of anti-gravity at opposite sides from point in question you would get increased gradient of field.
  19. Jul 1, 2011 #18
    Zonde, the observed, higher than predicted, rotational velocities of stars on the outsides of galaxies somehow requires a greater gravitional force towards the center of the galaxies otherwise they would move out to higher orbits or even be ejected altogether. So it seems to me that having a negative gravitational field outside the galaxy pushing these stars back in, might produce a similar effect as additional mass, but I am only a layman. I just scrapped a BSc in Physics and Electronics a long time ago, didnt even study GR at all as I recall. :)

    Last edited: Jul 1, 2011
  20. Jul 6, 2011 #19
    I tried to phrase my question without sounding like I was proposing unfounded ideas, but someone else came along and did it anyways.
    With that being said I'm glad that we got back to my question, I could've phrased it better so that everyone would have seen what I was trying to say, but it seems like the last two posts are moving toward the direction I intended.
  21. Jul 11, 2011 #20
    Hello, I'm new here and a layman by any terms of the word with a very general knowledge of mathematics.

    I have a few questions I was hoping some of you could help to answer. They are regarding dark matter and here they are together with some assumptions I have made that may not be correct.

    As I understand it, dark matter is a name we gave to "something" that seems to be adding gravity to the galaxies and causing them to remain together in a higher rate of spin as they would have otherwise.

    My first question is if this dark matter or "something" is in any way found to be somehow linked to gravity, by proportion or otherwise. As I understand it, this dark matter is a massless particle that adds gravity (?). I put this as a question because as I understand it, all the mass in the galaxy can be explained but what cannot be explained is the gravity associated with the galaxy so I assume that it is mass-less. If this is so, doesn't this seem a lot like the definition of a graviton?
    How absurd would it be to imagine that this dark matter has something to do with the messenger that pertains to gravity?

    My last question regarding dark matter is how large of a scale do we need to use before we can measure its effects. We already know that it can be measured at the scale of galaxies but can it be measured in smaller scales like individual stars? planets? moons? molecules? quantum level particles? More clearly, how large a scale do we need to go to before we see an anomaly in F=Gm1m2/r2?

    Well that's about it, I hope I haven't embarrassed myself too much and thanks for any answers.
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