Page 1 of 2 12 LastLast
Results 1 to 30 of 37

Thread: Ether... i mean, Dark Matter

  1. #1
    Join Date
    Jan 2007
    Posts
    51

    Ether... i mean, Dark Matter

    Hearing all this talk about dark matter... I can't help but find parallels to the fabled "Ether" of last century.

    "There has to be "ether," because our laws state that light-waves can NOT travel through space without it!"

    "There has to be "dark matter," because our laws state that those stars can NOT move that fast without it!"

    Anyone else find some similiarities?

  2. #2
    Join Date
    Mar 2004
    Posts
    15,754
    Quote Originally Posted by timeless View Post
    "There has to be "ether," because our laws state that light-waves can NOT travel through space without it!"

    "There has to be "dark matter," because our laws state that those stars can NOT move that fast without it!"

    Anyone else find some similiarities?
    No. Have you? Was the above one?
    Last edited by 01101001; 2007-Mar-19 at 02:40 AM.
    0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 ...
    Internet searches performed to your specifications. Direct gratuities (suggested $5/search) to Cosmoquest Petascale Server Fund.

  3. #3
    Join Date
    Feb 2007
    Posts
    1,168
    Quote Originally Posted by 01101001 View Post
    No. Have you? Was the above one?



    Straight to the point there what!? have to agree though.

  4. #4
    Join Date
    Jun 2002
    Posts
    1,810
    "Luminiferous dark matter" is a contradiction in terms.

  5. #5
    Join Date
    Sep 2003
    Posts
    1,498
    I find it potentially more like the discovery of the neutrino.

    "Beta decay violates conservation of momentum, angular momentum and energy. Either these well-established principles are wrong, and should be discarded, or there must be another particle emitted." What was violated, specifically, gave scientists a description of what the "missing" particle had to be. After a while, they confirmed its existence.

    With dark matter we're somewhere in the middle — getting an idea of what properties dark matter has to have, and devising ways to look for it.

  6. #6
    Join Date
    Mar 2007
    Posts
    393
    Dark matter doesn't necessarily mean exotic dark matter. Funny how no one seems to be searching for intergalactic dust bunnies and any other forms of regular matter which is not luminating or detectably obscuring distant light. Also, there is the semi-exotic normal matter we're finding - like the ultra dense galactic cores with hundreds of millions of solar masses stuffed into tiny objects - ostensibly super massive black holes. These seem to be present in anything with a nucleus bulge.

    Exotic DM does seem to be good for headlines and probably for better funding than more mundane concepts. And, it gives the particle hunter types an excuse to beg for more money and equipment.

  7. #7
    Join Date
    Sep 2006
    Posts
    1,728
    Quote Originally Posted by cbacba View Post
    Dark matter doesn't necessarily mean exotic dark matter. Funny how no one seems to be searching for intergalactic dust bunnies and any other forms of regular matter which is not luminating or detectably obscuring distant light.
    ...


    Exotic DM does seem to be good for headlines and probably for better funding than more mundane concepts. And, it gives the particle hunter types an excuse to beg for more money and equipment.
    Right. Well then, please give us an idea for a technique we can use to look for regular matter which a) doesn't emit radiation and b) is not detectably obscuring light from distant objects.

    Gee, it sounds as if we'd have to use some indirect method; that normal matter would still have mass, right, so we could search for its gravitational effect on objects which we _can_ see.

    Oh, wait, that's exactly what astronomers do. They find evidence for lots of gravitational force, without the matching emitted light. They call it "dark matter."

    The standard Big Bang theory predicts that only a certain amount of ordinary baryonic matter survived the hot phase of the universe. That amount is unable to provide as much gravitational force as we see in many places. Hence, the provisional hypothesis for non-baryonic dark matter.

    Again, I'd be very interested to hear several techniques we might use to test the notion that there is more baryonic matter than the Big Bang model suggests. Please tell us.

  8. #8
    Join Date
    Mar 2007
    Posts
    393
    Well, let's see,
    some people look for intergalactic dustbunnies (they usually refer to them by names like primordial fog particles or PFPs) by the microlensing effects that batches of them evidently produce when viewing distant objects such as quasars. I'm not sure how you're going to spot a lyman alpha cloud floating around at long distances from any ionizing stars. Dittos on how you see a supermassive blackhole at the center of a galaxy - although some folks think we may actually be able to eventually zoom in really close to the event horizon as techniques progress - assuming the object has an event horizon.

    As for PFPs (dust bunnies) not obscuring anything luminous, that's going to be a trick. You might just have to wait for them to collect enough mass, in rather low density areas, for them to finally start lighting up - or at least - to gain enough mass to release energy in a gravitational collapse. I wouldn't plan on waiting around that long if I were you.

    I'm not sure who coined the notion of exotic dark matter but it seems to have come about long before the search for normal dark matter (or at least baryonic dark matter) was exhausted.

    AFter all, astronomers are particularly biased towards luminous matter. In the past, they were highly biased towards only visible spectrum luminous matter, but with the advent of radio astronomy, infrared astronomy and the x-ray and gamma ray astronomy, they've expanded their horizons significantly in the last few decades.

    Trying to find anything non luminous generally requires it to be backlit. About the only thing around that can do that is the microscopic variances in the microwave background levels and that is so low it would seem to not be very suitable for much detection. If there is no way to detect something by that way, it would seem that a general luminous background would not be available. That being the case, perhaps there is no way to detect some of this material but then if these machos and wimps and other inventions of the apparent lack of baryonic matter don't exist, then they aren't going to be detected either.

    Perhaps a question should be - what is the schwartzchild radius for an object of the density that our universe is believed to be (including the inferred DM mass)?

  9. #9
    Join Date
    Sep 2005
    Posts
    3,066
    Since Non-baryonic DM is going right through all stars, planets, and everything else, there is only one thing that can 'confine' it to a small area...

    A BLACK HOLE

    and as Einstein indicated, space (which is the DM) is curved by ponderable matter (which is baryonic matter, stars, planets).

    So, the answer to the OP is yes.

  10. #10
    Join Date
    Oct 2001
    Posts
    7,732
    Quote Originally Posted by RussT View Post
    Since Non-baryonic DM is going right through all stars, planets, and everything else, there is only one thing that can 'confine' it to a small area...

    A BLACK HOLE
    Huh?

    and as Einstein indicated, space (which is the DM) is curved by ponderable matter (which is baryonic matter, stars, planets).
    Huh, again? Gravitationally, matter is matter!

  11. #11
    Join Date
    Feb 2007
    Posts
    1,168
    Quote Originally Posted by Kaptain K View Post
    Huh?


    Huh, again? Gravitationally, matter is matter!


    I do like a statement with, Substance

  12. #12
    Join Date
    Sep 2005
    Posts
    3,066
    Quote Originally Posted by Kaptain K View Post
    Huh?


    Huh, again? Gravitationally, matter is matter!
    NOT, if it is "Inert" and traveling at "C"!

  13. #13
    Join Date
    Oct 2001
    Posts
    7,732
    Quote Originally Posted by RussT View Post
    NOT, if it is "Inert" and traveling at "C"!
    If it is traveling at "c", it is not matter (dark or otherwise).

  14. #14
    Join Date
    Jan 2006
    Posts
    1,816
    Quote Originally Posted by RussT View Post
    Since Non-baryonic DM is going right through all stars, planets, and everything else, there is only one thing that can 'confine' it to a small area...

    A BLACK HOLE
    Matter cannot fall into a black hole without losing angular momentum. Regular matter, heated to billions of degrees, radiates away angular momentum quite nicely, and spirals in. But since Dark Matter--by definition--does not radiate, it cannot lose angular momentum very efficiently, ergo, will not tend to fall into a BH.

    Black-holes are not harbors of black matter...I mean dark matter

  15. #15
    Join Date
    Nov 2002
    Posts
    6,207
    Quote Originally Posted by RussT View Post
    NOT, if it is "Inert" and traveling at "C"!
    If it's traveling at c, then it is energy, not matter. And to expand a bit on what the good Kaptain wrote, while matter is matter and energy is energy, gravitationally, matter and energy are the same.

  16. #16
    Join Date
    Sep 2005
    Posts
    3,066
    Quote Originally Posted by Kaptain K View Post
    If it is traveling at "c", it is not matter (dark or otherwise).
    BUT is is NON-baryonic.

  17. #17
    Join Date
    Sep 2005
    Posts
    3,066
    Quote Originally Posted by Peter Wilson View Post
    Matter cannot fall into a black hole without losing angular momentum. Regular matter, heated to billions of degrees, radiates away angular momentum quite nicely, and spirals in. But since Dark Matter--by definition--does not radiate, it cannot lose angular momentum very efficiently, ergo, will not tend to fall into a BH.

    Black-holes are not harbors of black matter...I mean dark matter
    So what do you think is 'making up the mass' of millions to billions of sol masses in SMBH's?

  18. #18
    Join Date
    Oct 2001
    Posts
    7,732
    Quote Originally Posted by RussT View Post
    So what do you think is 'making up the mass' of millions to billions of sol masses in SMBH's?
    Mass (baryonic and DM) and energy (which, gravitationally is equivalent to mass).

  19. #19
    Join Date
    Sep 2005
    Posts
    3,066
    Quote Originally Posted by Tensor View Post
    If it's traveling at c, then it is energy, not matter. And to expand a bit on what the good Kaptain wrote, while matter is matter and energy is energy, gravitationally, matter and energy are the same.
    When Zwickey first introduced dark matter (back then it was definitely 'baryonic') for cluster dynamics and Then when Vera Rubin determined the rotation curve of stars in spiral galaxies to be a problem that apparently needs 'extra gravity' to be present to 'fit the observations', the HUNT was on!

    Once it was 'fairly obvious' that baryonic matter could NOT be found in enough quantity to be the 'extra gravity', that is when Mainstream (?) introduced Non-Baryonic Dark Matter.

    Einstein had ZERO idea/concept about this (along with SMBH's, Vast Voids, Inflation, or Modern 11d String/"M" Theory) and therefore, Mainstream HAS introduced NEW PHYSICS into the mix!!!

    They have also "Retro fitted' both CDM and Neutrino's into the early primordial universe and basically 'form fitted' the explanations of these to what is needed to come out right.

    I am agreeing that mainstream has done an excellent job of showing that there is just not enough baryonic matter to be the 'extra gravity', SO I am also agreeing the the Non-Baryonic Dark Matter is 'there', HOWEVER,

    Where it comes from, what makes it, how much of it there is, how it moves, and especially, HOW FAST IT IS GOING, is all debatable in as much as it is definitely NEW PHYSICS and needs to remain an open question, especially considering that we do NOT know "WHY" gravity is SO WEAK.

    Einstein certainly could NOT have conceived of electrons going through his body in profuse amounts, so what do you think he would have thought about Neutrinos and DM?

  20. #20
    Join Date
    Oct 2001
    Posts
    7,732
    ...so what do you think he would have thought about Neutrinos and DM?
    Perry Mason voice "Immaterial, irrelevant and not germane to the point!" /Perry Mason voice
    Time and Science marches on.
    They have also "Retro fitted' both CDM and Neutrino's into the early primordial universe and basically 'form fitted' the explanations of these to what is needed to come out right.
    Hey, that's how science works. If the data does not fit the theory, the first thing you do not do is throw everything out and start over. The first thing is see if the theory can be modified (improved) to explain the new data.

    One thing you may be missing is that while we throw around "dark matter" and "dark energy" like we know what we are talking about, astrophysicists and cosmologists use DM and DE as "placeholders" for stuff that we haven't figured out yet. The characteristics of DM and DE are not unconstrained. Whatever they are, their properties do affect baryonic matter in the ways we observe.

  21. #21
    Join Date
    Mar 2004
    Posts
    13,440
    Quote Originally Posted by cbacba View Post
    Well, let's see,
    some people look for intergalactic dustbunnies (they usually refer to them by names like primordial fog particles or PFPs) by the microlensing effects that batches of them evidently produce when viewing distant objects such as quasars. I'm not sure how you're going to spot a lyman alpha cloud floating around at long distances from any ionizing stars. Dittos on how you see a supermassive blackhole at the center of a galaxy - although some folks think we may actually be able to eventually zoom in really close to the event horizon as techniques progress - assuming the object has an event horizon.

    As for PFPs (dust bunnies) not obscuring anything luminous, that's going to be a trick. You might just have to wait for them to collect enough mass, in rather low density areas, for them to finally start lighting up - or at least - to gain enough mass to release energy in a gravitational collapse. I wouldn't plan on waiting around that long if I were you.

    I'm not sure who coined the notion of exotic dark matter but it seems to have come about long before the search for normal dark matter (or at least baryonic dark matter) was exhausted.

    AFter all, astronomers are particularly biased towards luminous matter. In the past, they were highly biased towards only visible spectrum luminous matter, but with the advent of radio astronomy, infrared astronomy and the x-ray and gamma ray astronomy, they've expanded their horizons significantly in the last few decades.

    Trying to find anything non luminous generally requires it to be backlit. About the only thing around that can do that is the microscopic variances in the microwave background levels and that is so low it would seem to not be very suitable for much detection. If there is no way to detect something by that way, it would seem that a general luminous background would not be available. That being the case, perhaps there is no way to detect some of this material but then if these machos and wimps and other inventions of the apparent lack of baryonic matter don't exist, then they aren't going to be detected either.

    Perhaps a question should be - what is the schwartzchild radius for an object of the density that our universe is believed to be (including the inferred DM mass)?
    There seems to be some confusion here ... "regular matter", in your first post in this thread ("baryonic dark matter" in the post I'm quoting here), is detectable, if it's in the form of dust or gas - from its emission (cool dust is a terrific emission source, as the various IR surveys have demonstrated; hot gas the same, in the x-ray part of the spectrum), or absorption (reddening, lines, bands, ...).

    Regular matter in the form of pebbles, rocks, boulders, asteroids, rogue planets: these may indeed escape direct detection. The reason why these cannot comprise more than a small fraction of the estimated DM in rich clusters and galaxy halos is indirect, but pretty compelling: there's far too much DM. H and He could amount to no more than a trivial (mass) fraction of these solid (or partly solid, partly liquid, in the case of the bigger ones) objects. Why? Because the estimated DM far exceeds the amount of other matter, and that other matter is overwhelmingly H + He ("metals" - astronomers' term for the elements Li to the trans-uranium ones - comprise a mere percent or three). Also, if there were so much regular mass in this form, how come the solar system isn't being bombarded by high velocity extra-solar pebbles through rogue planets?

    Regular matter in the form of dead white dwarfs, dead brown dwarfs, M, T, and L dwarfs, etc: several studies, using microlensing, have looked for these, and failed to find them in sufficient numbers - they do exist, but can make up only a tiny fraction of the estimated DM.

    PFPs: this is the first time I've come across this term, but from your description, it seems they are certainly not 'regular matter'.

    That leaves intermediate black holes (say, a few hundred to a few thousand sols) and various kinds of primordial black holes. AFAIK, neither of these can be ruled out, by astronomical observations, as possible components of DM. But whatever you think of BHs, they sure aren't 'regular matter'.

  22. #22
    Join Date
    Jan 2006
    Posts
    1,816
    There are parallels between the ether of 19th century and DM of the 20th/21st centuries, just as there are similarities between the puff of smoke given off by a match being lit and the mushroom cloud of an atomic bomb.

    Considering the effort that has been put into identifying dark matter, relative to the effort in 19th cent. to identify "ether," however, I would suggest it is really not a fair comparison. The ether hypothesis remained in effect until it became untenable, at which point it was abandoned.

    Dark matter remains very tenable.

  23. #23
    Join Date
    Mar 2007
    Posts
    393
    "PFPs: this is the first time I've come across this term, but from your description, it seems they are certainly not 'regular matter'."

    PFPs have been associated with microlensing (not proven but associated with). Think of them as cold planets, preborn pre brown dwarfs (if not simply rogue planetoids) - perhaps in the process of forming in sparse neighborhoods - hence the time to cool off from the gravitational collapsing and the reason why they are far from becoming lit up as a nuclear powered star. Being far away from anything serious, and being very old, they should have had time to have be approaching room temperature so to say. Dust bunny makes a more amusing and memorable name though in my opinion.

    To the best of my knowledge, the PFP is considered standard baryonic matter - just much denser than a dust cloud or gas cloud as it is a protostar or planetoid.


    "There seems to be some confusion here ... "regular matter", in your first post in this thread ("baryonic dark matter" in the post I'm quoting here), is detectable, if it's in the form of dust or gas - from its emission (cool dust is a terrific emission source, as the various IR surveys have demonstrated; hot gas the same, in the x-ray part of the spectrum), or absorption (reddening, lines, bands, ...)."

    It's rather hard for something that has essentially reached 'room temperature' to be detectable by - unless there is absorption from emissions behind it. If there is no serious sources of radiant energy in the general vacinity of some 'cloud'. Absorption in very tenuous gas clouds (ultra low density) at very low temperatures is not well studied (as I understand it) and cannot be assumed to be the same as laboratory results. Lyman alpha clouds also have evidently been found even in the intergalactic void. (which are probably fairly hot and are absorbing)

    Currently accepted theory has it that the moon was formed after a Mars sized object splatted into the earth a few billion years back. We assume there is an Oort cloud out there from whence comets come from as they get their orbits shifted into inner solar system ones. There's evidence for plenty of stuff that possibly could be out there. Besides, we've been in this galactic orbit for several spins around the galaxy - you'd think we'd do a bit of a number on clearing out the orbit at least a little bit - maybe somewhat better than poor ole Pluto.

    I consider BHs to be regular matter as they are created from regular matter. Even if they are no longer consisting of it. If The missing matter is explainable by as yet undetected regular (baryonic) matter (all forms including BH) then the need for exotic stuff may not be necessary and that stuff may turn out to be simply pie in the sky imagination a temporarily useful kluge (perhaps one that delayed the determination of the regular matter approach).

  24. #24
    Join Date
    Sep 2005
    Posts
    3,066
    Quote Originally Posted by Kaptain K
    Hey, that's how science works.
    Sounds like pure objectivity to me.

    Quote Originally Posted by Kaptain K
    The first thing is see if the theory can be modified (improved) to explain the new data.
    Translation...'Constrain' (and there is a whole lot of 'constraining go'in on!) it to fit the current paradigm and then call it 'observation'!

    The only valid constraints are that Non-baryonic DM 'exists' in galaxies and galaxy clusters!!! That, as I said in another thread IS Non-Big Bang/GR dependent!!! That is what is "Observed"...is that it is THERE/exists in galaxies and clusters.

    Quote Originally Posted by Kaptain K
    One thing you may be missing is that while we throw around "dark matter" and "dark energy" like we know what we are talking about, astrophysicists and cosmologists use DM and DE as "placeholders" for stuff that we haven't figured out yet. The characteristics of DM and DE are not unconstrained.
    Uh, NO, I'm not missing it at all! It is my very point!

    Quote Originally Posted by Kaptain K
    Whatever they are, their properties do affect baryonic matter in the ways we observe.
    So this is totally based on 'assumptions' that are based on the DM being 'slow' and 'cold' and within a certain constrained size/energy parameter, so that it can be treated as you need it to be so it can become a "Galaxy Halo" of DM that can 'somehow' partially clump the way you need it to. Then it is just put into the 'primordial early universe' as to where it 'had' to have formed, 'again somehow' (how when it's straight line motion can only be altered very slightly by stars and planets, and it takes a MBH to be able to curve it all the way in to an event horizon). Etc.

    And then the kicker is that the only real 'observations' for 'galaxy halo's' is
    N-body simulations.

    And then it is defended to the hilt!

    And then I get posts like this...
    http://www.bautforum.com/showpost.ph...4&postcount=13

  25. #25
    Join Date
    Sep 2005
    Posts
    3,066
    Quote Originally Posted by Peter Wilson View Post
    There are parallels between the ether of 19th century and DM of the 20th/21st centuries, just as there are similarities between the puff of smoke given off by a match being lit and the mushroom cloud of an atomic bomb.

    Considering the effort that has been put into identifying dark matter, relative to the effort in 19th cent. to identify "ether," however, I would suggest it is really not a fair comparison. The ether hypothesis remained in effect until it became untenable, at which point it was abandoned.

    Dark matter remains very tenable.
    Again, Einstein, Micholson/Morley, Lorentz, ETC could NOT find an Aether/medium because there was NO concept of Non-baryonic DM At all back then, AND if it is traveling at "c" and going right through baryonic matter (which they could NEVER envisage back then), what is so hard to believe about the fact that it has taken over 100 years to find it???

    In addition, the Non-baryonic DM is at the very heart of unifying GR and QFT. Where it comes from, what makes it, how fast it is going, and the fact that it is virtually "inert", are all clues. Also, what causes the energy that is contained in the "Inert' DM to be released, where does this happen, how does it manefest, are all questions that need to be answered.
    Last edited by RussT; 2007-Mar-24 at 09:47 AM.

  26. #26
    Join Date
    Mar 2004
    Posts
    13,440
    Quote Originally Posted by cbacba View Post
    "PFPs: this is the first time I've come across this term, but from your description, it seems they are certainly not 'regular matter'."

    PFPs have been associated with microlensing (not proven but associated with). Think of them as cold planets, preborn pre brown dwarfs (if not simply rogue planetoids) - perhaps in the process of forming in sparse neighborhoods - hence the time to cool off from the gravitational collapsing and the reason why they are far from becoming lit up as a nuclear powered star. Being far away from anything serious, and being very old, they should have had time to have be approaching room temperature so to say. Dust bunny makes a more amusing and memorable name though in my opinion.

    To the best of my knowledge, the PFP is considered standard baryonic matter - just much denser than a dust cloud or gas cloud as it is a protostar or planetoid.


    "There seems to be some confusion here ... "regular matter", in your first post in this thread ("baryonic dark matter" in the post I'm quoting here), is detectable, if it's in the form of dust or gas - from its emission (cool dust is a terrific emission source, as the various IR surveys have demonstrated; hot gas the same, in the x-ray part of the spectrum), or absorption (reddening, lines, bands, ...)."

    It's rather hard for something that has essentially reached 'room temperature' to be detectable by - unless there is absorption from emissions behind it. If there is no serious sources of radiant energy in the general vacinity of some 'cloud'. Absorption in very tenuous gas clouds (ultra low density) at very low temperatures is not well studied (as I understand it) and cannot be assumed to be the same as laboratory results. Lyman alpha clouds also have evidently been found even in the intergalactic void. (which are probably fairly hot and are absorbing)

    Currently accepted theory has it that the moon was formed after a Mars sized object splatted into the earth a few billion years back. We assume there is an Oort cloud out there from whence comets come from as they get their orbits shifted into inner solar system ones. There's evidence for plenty of stuff that possibly could be out there. Besides, we've been in this galactic orbit for several spins around the galaxy - you'd think we'd do a bit of a number on clearing out the orbit at least a little bit - maybe somewhat better than poor ole Pluto.

    I consider BHs to be regular matter as they are created from regular matter. Even if they are no longer consisting of it. If The missing matter is explainable by as yet undetected regular (baryonic) matter (all forms including BH) then the need for exotic stuff may not be necessary and that stuff may turn out to be simply pie in the sky imagination a temporarily useful kluge (perhaps one that delayed the determination of the regular matter approach).
    I did some digging ... it seems that this PFP idea comes from some work by Carl H. Gibson, and that there are practically no papers on this idea, in the relevant peer-reviewed technical literature, that do not have Gibson (or Rudolph E. Schild) as an author.

    Unless some BAUT member can present a strong case to the contrary, I think we can safely regard this as an ATM idea (and so further discussion on it needs to take place in BAUT's ATM section).

  27. #27
    Join Date
    May 2008
    Posts
    1,153
    Quote Originally Posted by Squink View Post
    "Luminiferous dark matter" is a contradiction in terms.
    nope, not a contradiction at all depending on context

    the term "Luminiferous" means Generating, yielding, or transmitting light.
    http://www.thefreedictionary.com/luminiferous

    air is luminiferious, so is water.

    in this context, the ether is the actual medium that electromagnetic radiation propagates through just like sound sound energy propagates through matter being solid, gas or liquid.



    According to the general theory of relativity space without ether is unthinkable; for in such space there not only would be no propagation of light, but also no possibility of existence for standards of space and time. But this ether may not be thought of as endowed with the quality characteristic of matter, as consisting of parts ('particles') which may be tracked through time.
    (Albert Einstein, 1928, Leiden Lecture)

    is this ether that Einstein talks about actually the "dark matter" that we are trying so hard to understand today?

  28. #28
    Join Date
    Apr 2007
    Posts
    1,188
    Quote Originally Posted by Peter Wilson View Post
    Matter cannot fall into a black hole without losing angular momentum.
    That's obviously false. For a given black hole some particles will be have motion vectors that correspond to event horizon crossing orbits. They donate their angular momentum to the BH.

    Quote Originally Posted by Peter Wilson View Post
    Regular matter, heated to billions of degrees, radiates away angular momentum quite nicely, and spirals in.
    How can angular momentum be radiated away? Isn't thermal radiation symmetrical? I thought the standard theory was that angular momentum was lost as a wind.

    Quote Originally Posted by Peter Wilson View Post
    But since Dark Matter--by definition--does not radiate,
    I see many papers on arxiv that invoke dark matter annihilation as a source of radiation. Dark matter scattering is also sometimes hypothesized to explain various phenomena.

    Quote Originally Posted by Peter Wilson View Post
    it cannot lose angular momentum very efficiently, ergo, will not tend to fall into a BH.

    Black-holes are not harbors of black matter...I mean dark matter
    The orthodox theory of black holes is that they don't harbor matter, only mass, charge and angular momentum (Is Hawking still orthodox on this?). So BHs cannot harbor dark matter any more than they can harbor television sets.

  29. #29
    Join Date
    Jun 2007
    Posts
    5,467
    Quote Originally Posted by timb View Post
    How can angular momentum be radiated away? Isn't thermal radiation symmetrical? I thought the standard theory was that angular momentum was lost as a wind.
    If you look at the accretion disk from the side (from a non-rotating point of view), one side will be red shifted and the other blue shifted. Don't know how significant this is in angular momentum loss, though, and I do recall reading about a wind of high velocity particles that saps energy from the disk (a bit like evaporative cooling).

  30. #30
    Join Date
    Aug 2003
    Location
    The Wild West
    Posts
    9,228
    Quote Originally Posted by sabianq View Post
    ...is this ether that Einstein talks about actually the "dark matter" that we are trying so hard to understand today?
    First of all, Einstein was not always right. Second, dark matter is surely not an "ether." If you need an ether to sleep at night, consider the Higgs ocean. It's not luminiferous in the sense previously thought, so it's a totally different etherial concept than the one conjectured in the late 19th Century; but hey, in the long run, science marches forward.
    Everyone is entitled to his own opinion, but not his own facts.

Similar Threads

  1. Anti-Matter, Dark-Matter, Missing Matter
    By transreality in forum Space/Astronomy Questions and Answers
    Replies: 14
    Last Post: 2011-Mar-11, 09:32 AM
  2. Replies: 10
    Last Post: 2010-Nov-17, 06:24 PM
  3. Replies: 1
    Last Post: 2009-Apr-23, 04:04 AM
  4. Replies: 0
    Last Post: 2008-Aug-27, 06:00 PM
  5. How does matter get its mass from the ether?
    By wisp in forum Against the Mainstream
    Replies: 9
    Last Post: 2005-Dec-10, 08:52 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •