Anti-Dark Matter

Discussion in 'Physics & Math' started by joepistole, Nov 18, 2012.

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  1. joepistole Deacon Blues Valued Senior Member

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    If there is dark matter, as most professional physicists seem to think, and dark matter consists of slow moving particles, then shouldn’t there be anti-dark matter particles? And how do you explain the existence of so much dark matter? What happened to all the anti-dark matter?

    http://chandra.harvard.edu/blog/node/351
     
    Last edited: Nov 18, 2012
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  3. Tach Banned Banned

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    There is no rule that there should be equal quantities of matter and anti-matter. Therefore, there is no expectation that there is anti-dark matter, much less than the anti dark matter exists in a quantity commensurable with the one of dark matter.
     
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  5. brucep Valued Senior Member

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    There's direct evidence that dark matter exists. WMAP says 23% of the observable universe is dark matter.
    A direct empirical proof of the existence of dark matter
    http://arxiv.org/abs/astro-ph/0608407

    Should there be anti dark matter? So far science knows it interacts with matter gravitationally but not electromagnetically [at least not in the normal way]. The following is the proposal I find most interesting. Robert Foot's Mirror Dark Matter.
    http://arxiv.org/pdf/astro-ph/0407623.pdf
    This is really easy to read.
    Does Mirror Matter exist?
    http://arxiv.org/pdf/hep-ph/0207175v1.pdf
     
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  7. Trippy ALEA IACTA EST Staff Member

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    I'll have to have a look when I have more time, but, I have a recollection that there is at least one WIMP theory that predicts that dark matter is its own anti-particle, an that one of the pathways involves the production of an positron electron pair. I have a feeling that there were some GLAST results that looked promising, but I have an inkling they might have been shown to be inconsistent at some point. Having said that I also have a recollection that the GLAST results had recently been bought back into the running by a new study.
     
  8. Farsight Valued Senior Member

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    I got as far as the first line: "There is a very strong scientific case that most of the matter in the Universe consists of non-baryonic stable particles." There isn't any evidence for this at all. We have good evidence that there's something that causes flat galactic rotation curves, and we tend to call it "dark matter". But we have no evidence whatsoever that it consists of non-baryonic stable particles. An important reminder is provided by the self-energy of a gravitational field, which in itself causes gravity. That gravitational field energy has a mass-equivalence, but it is not made up of non-baryonic stable particles. Don't forget that gravitons remain hypothetical, and would be virtual particles at best - field quanta rather than actual particles.

    I'm also unimpressed when I read things like this:

    "The mirror partners have the same mass as their ordinary counterparts, which is reminisant of anti-particles. However, there is a crucial difference. Unlike anti-particles, the mirror particles interact with ordinary particles predominately by gravity only. The three non-gravitational forces act on ordinary and mirror particles completely separately [and with opposite handedness: where the ordinary particles are left-handed, the mirror particles are right-handed]."

    This doesn't recognise the opposite chirality of particles and antiparticles. The end-product is an unsupported conjecture I'm afraid. And that's putting it kindly. If some poster here had advanced this idea, it would get short shrift.
     
  9. Tach Banned Banned

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    Huh?
     
  10. PhysBang Valued Senior Member

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    Maybe you should actually read something rather than simply ignore anything that might inform you that your beliefs are incorrect? (Why not learn the math of the physics that you claim to know?) The evidence for dark matter is not simply about flat rotation curves. Indeed, it is truly moronic to claim that these are the best evidence for dark matter.
    Now we get to the lying part of your post.

    You know that scientists have actually worked out the influence of the gravitational field on things like the Earth and on galaxies. You know that they have demonstrated that it is far too miniscule to do anything on the order of magnitude of dark matter effects. I know this because we can see you retracting this insane claim that you made above when pressed on other boards. If you want to defend this insane claim in an honest way, you would learn the relevant math and then show directly the impact of these effects. It can be done; you need only show how the many scientists that you are insulting have done their math incorrectly.

    Again, given that you cannot do this and you have been asked about this before, you are simply lying when you present this idea as an alternative to dark matter.
     
  11. brucep Valued Senior Member

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    Good [informative] post PhysBang. Thanks for writing it down. He should change his user name to shortsight or blindsided.
     
    Last edited: Nov 18, 2012
  12. brucep Valued Senior Member

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    You're a nonsense machine so most folks are going to hopefully recognize that FACT. The team that did the weak lensing research don't give a crap 'what internet cranks think about their work'. As PhysBang said you can't even do a real analysis of the physics so your opinion is irrelevant.
     
  13. Farsight Valued Senior Member

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    I didn't. I merely mentioned one item of evidence.

    No I don't. And the fact remains that a gravitational field is an example of something that causes gravity and which doesn't consist of particles. That isn't a lie. That's relativity.

    I haven't retracted this anywhere. And again, a gravitational field is an example of something that causes gravity and which doesn't consist of particles. If some people find that insulting because their reputations hang on WIMPs which remain undetected after decades, that's their problem.

    I'm not lying. But you are over-reacting. In fact, you're sounding desperate.


    What I said is true. Let me reiterate in case you missed it the first time. There is no evidence that most of the matter in the Universe consists of non-baryonic stable particles. There's no evidence to support Foot's conjecture either. If you beg to differ, show us some. But if you can't, outrage and abuse aren't going to make up for it.


    Go look it up. Search on say positron chirality. Chirality is "handedness". The positron has the opposite chirality to the electron. Your left hand reflected in mirror looks like your right hand. Antimatter is "mirror matter". So Foot's conjecture falls at the first hurdle.
     
  14. Trippy ALEA IACTA EST Staff Member

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  15. Tach Banned Banned

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    Once again: "Huh?". Where do you see that the author "doesn't recognise...". Quite the opposite the text shows clearly that the author knows the basics.
     
  16. PhysBang Valued Senior Member

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    Again you lie. You only mentioned one piece of evidence. Then you neglected every significant piece of evidence, like you do on every topic in physics.
    I see that, as always, you fail to address any of the science that I or anyone else knowledgeable on the subject brings up. That is a lie of omission; a predicable one.

    You claim to know GR (yet demonstrably do not). If you want to show that everyone working on galactic and galaxy clustering dynamics for the last 90 years is wrong, then all you have to do is show us how to account for the "self-energy of a gravitational field". You need merely show the amount of the influence, that it is significant to the dynamics, and how those who have previously calculated this same part of the physics have been mistaken. (You should also show why the people who have calculated this for the Earth were wrong and what corrections we should thus make to satellite and solar system dynamics. You might also want to tell the moon to change its orbit to the correct Farsight orbit.)
    Indeed, no evidence other than the evidence. Can you show us where the WMAP work is wrong, Farsight?
    You should remember this. No one will take your outrage and abuse seriously unless you can show us the basis for your claims in the science. You have lied in your claims of the "self-energy of a gravitational field" and your continued failure to produce one shred of evidence in favor of your position demonstrates this.
     
  17. brucep Valued Senior Member

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    You're recollection is just fine. Other than knowing dark matter exists, how much, it interacts gravitationally, and doesn't interact electromagnetically [at least in a way which would make it visible to detection] it's a crap shoot. I agree with everything this Prof says about WIMPs [if they exist, duh].
    Query: Do WIMPs have antiparticles?
    http://www.madsci.org/posts/archives/2012-04/1335415060.Ph.r.html

    When I first read Robert Foot's paper "Does Mirror Matter Exist"
    Does Mirror Matter exist?
    http://arxiv.org/pdf/hep-ph/0207175v1.pdf
    And the proposal for Mirror Dark Matter
    Robert Foot's Mirror Dark Matter.
    http://arxiv.org/pdf/astro-ph/0407623.pdf

    I was fascinated in a similar way to my initial fascination with Guth's Inflationary Universe. A good thing is we won't have to wait for the great CMBR experiments to test theoretical predictions for Mirror Dark Matter. There's ongoing experiments doing this as we speak. There's a proposal to build an experiment in the Southern Hemisphere to have better access to Mirror Dark Matter particles [if they exist]. You can look at cite base to find more recent technical discussion about the experiments and the theoretical predictions. The following encapsulates some experimental results and the proposal for the Southern Hemisphere experiment. Trippy stuff. Pun intended.

    http://indico.cern.ch/getFile.py/ac...nId=5&resId=0&materialId=slides&confId=189477

    This slide show covers most the proposal.
     
  18. LaurieAG Registered Senior Member

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    Charles Dodgson gave a bit of thought to all these different matters and at least his stories return back to reality at the end.

    http://en.wikipedia.org/wiki/Alice's_Adventures_in_Wonderland
    http://en.wikipedia.org/wiki/Through_the_Looking-Glass
     
  19. Farsight Valued Senior Member

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    I haven't lied at all. We know there's something out there that causes flat galactic rotation curves and other phenomena, but we have absolutely no evidence whatsoever that it's made up of WIMPs or any other form of non-baryonic stable particles. Read the paper Trippy linked to. And do please try to resist ad-hominem abuse. It's no substitute for hard scientific evidence.
     
  20. prometheus viva voce! Moderator

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    Au contraire
     
  21. Farsight Valued Senior Member

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    Pay attention to what I said: "We have good evidence that there's something that causes flat galactic rotation curves, and we tend to call it 'dark matter'. But we have no evidence whatsoever that it consists of non-baryonic stable particles." Now read what your own link and pay attention to what that says: "Thus, SBBN does not provide evidence that most of the baryons in the Universe are dark." It also says this: "It indicates that most of the matter in the Universe consists of nonbaryonic dark matter". It doesn't say that the dark matter consists of WIMPs or any other kind of non-baryonic particles.
     
  22. prometheus viva voce! Moderator

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    What is the difference between a WIMP and non-baryonic dark matter? (this is not a joke)
     
  23. PhysBang Valued Senior Member

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    Again you lie by omission. You have said that dark matter can be accounted for by "self-energy of a gravitational field". Can you demonstrate this? Can you show where every person working in this field has gone wrong in their calculations and in ignoring this particular feature of GR as irrelevant to the problem?

    It is not an ad hominem to point out that you are not offering an argument. It is relevant to the discussing to point out that you are repeating the same demonstrable lies.
     
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