There is no dark matter

[observer7]

--there is no such thing as dark matter-- <br /><br />instead, there are other exlainations for the erroneous rotation rates of galaxies. Most notable among the alternate theories is that the gravitational constant is not. For large scale structures, the force of gravity is manifest in a way that is not consistent with what we observe on Earth/Solar System wide scales. <br /><br />This idea appeals to me, because I picture gravity in avery Eistein like fashion (the elastic sheet being bent) and I can visualize little pockets of gravity (stars) that sit in a larger depression (galaxy) in such a way that the sum of the stars gravity is much less then the total of the galaxy. This also works on smaller scales (ie why two bowling balls don't attract each other in a very visible way). <br /><br />Now I know tha the math seems to work for very small and very large masses. It (gravitational constant) also has been measured to very presice values and it works. I just think that this alternate theory has some merits like <br /><br />- doesn't require a new class of "stuff" in the universe <br />- only requires a slight modification in the gravitational constant at different scales <br />- can be used to develop a cosmological model that is consistent with CMB observations and required energy density of the known universe <br />- might explain the observed acceleration of universal expansion (given a proper curve to the scale factor, it is possible that gravity is strongest at galactic/galactic neighborhood scales and falls off on both sides, larger and smaller) <br />- can encompass both Newtonian and Einsteinian gravity within the larger theory <br /><br /><br />I think it might also have implications for quatum gravity and black holes. <br /><br />Your thoughts on the subject please.<br /> <div class="Discussion_UserSignature"> <em><font size="2">"Time exists so that everything doesn't happen at once" </font></em><font size="2">Albert Einstein</font> </div>

 

[search]

Saying there is no dark matter is rejecting a very valid theory. Even the dark matter theorist do not reject (or should not) the contender theories.<br /><br />The fact is that there is a big degree of uncertainty on this subject and it is necessary to look for a solution from several angles. <br /><br />An example of attemting to improve Eintein Theory:<br />http://www.innovations-report.de/html/berichte/geowissenschaften/bericht-55201.html <br /><br />The abstract on that theory:<br />http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2006ApJ...638L...9Z<br /><br />As you can read. The problem is that for somethings it works and for others it does not and then there is also the degree to which the observation can match with this theories.<br /><br />What we can say is that it is an open subject and it should be trated as such keeping the options open and leaving behind the emotional attachment that humans are so good at when they came up with ideas otherwise science becames a field of ideologies instead of a field of ideas.

 

[observer7]

I completely agree with the idea of keeping an open mind.<br /><br />What I'm looking for is how good are the alternates? I can find thousands of papers or references on dark matter, its harder to find alternate information. <br /><br />Who can educate me on the pros and cons of MOND? or other theories that do not subscribe to dark matter?<br /><br />-- <div class="Discussion_UserSignature"> <em><font size="2">"Time exists so that everything doesn't happen at once" </font></em><font size="2">Albert Einstein</font> </div>

 

[harmonicaman]

<b>SEARCH -</b><br /><br />I agree with what you said about Dark Matter, it's still all open to conjecture. Don't rule anything out yet!<br /><br />If you have an original idea about Dark Matter, you should present it to the forums for debate and criticism without any undignified emotional hyperbole. Scientific ideas are more correct or less correct based on reality and not on how excited you are about it...

 

[search]

Try the MOND pages<br />

 

[search]

Ok. Then check this

 

[eso44527]

Angus et al looked at the new bullet cluster results in the context of TeVeS and showed that contrary to the claims of Clowe et al, the cluster is consistent with MOND if there is additional mass in the form of neutrinos.

 

[eso44527]

A significant problem with DM is the preferred DM candidate (cold dark matter) rather than the inference that some form of DM might explain the observations. Specifically CDM is supposed to be a collisionless particle - meaning that the interaction with normal matter is only gravitational. On galaxy cluster and supercluster scales CDM seems to work pretty well. But on the scale of individual galaxies CDM fails in several ways. <br /><br />First, the predictions of computer simulations are notconfirmed by observations in a number of ways - the most critical being that the density of the DM halo in the core is greater in simulations than inferred from observations ("cuspy" core problem). But even if we assume that these types of problems will disappear with improved simulations, there is a more significant problem: observations of galaxies reveal in numerous ways a tight coupling between the distribution of luminous matter and the distribution of the inferred DM. This coupling is unexpected for a collisionless particle such as CDM. <br /><br /> Sancisi discussed this problem - but there are numerous other papers that can be cited revealing the same problem. <br /><br />The problem is actually as old as the candidacy of CDM. Bahcall & Casertano pointed out in 1985 that there is a lack of any feature in spiral galaxy rotation curves to indicate the transition between baryonic matter dominance and DM halo dominance. Such a feature should be present if the Halo is made of a collisionless particle. The lack of such a transition requires that either dark and lumonous mass are coupled (and therefore not CDM) or a fine tuning in the distribution of the dark and lumonous matter (disk-halo conspiracy).

 

[observer7]

Thanks everyone.<br /><br />Let me look this over to see if I'm duplicating something with my idea and I'll put together some pictures and (ugh) MATH to see how it works. Depending on my work schedule I should have this mid-week.<br /><br />Thanks again.<br /><br />-- <div class="Discussion_UserSignature"> <em><font size="2">"Time exists so that everything doesn't happen at once" </font></em><font size="2">Albert Einstein</font> </div>

 

[newtonian]

Observer7 - Perhaps there is no exotic dark matter, but I suspect there is.<br /><br />Certainly there is matter which is dark from an astronomer's point of view, observationally. A white dwarf will eventually change (or, er, evolve) into a dark mass quite invisible, hence dark matter.<br /><br />I have a theory to posit independently:<br /><br />What if there are exotic forms of matter which are not effected as strongly by gravity, hence exist in halo's around galaxies more than in the centers of said galaxies?<br /><br />Could dark matter have expanded faster initially, and then pulled more ordinary matter later in a sort of inflationary model?<br /><br />Could, in fact, this dark matter have mostly accelerated beyond our visibility horizon and be the cause of acceleration of expansion - perhaps by something akin to gravity from dark matter effecting the slower ordinary matter within our visibility horizon by a sort of domino effect caused by overlapping light cones (consider each light cone to be one domino which has cause and effect relationships directly with closer light cones (adjacent dominoes) but also has by said domino effect a cause and effect relationship with matter beyond its light cone, notably our observable universe's light cone, aka our visibility horizon.<br /><br />Simply put, dark energy could be ordinary gravity from dark matter from beyond our visibility horizon by a domino effect - at least in part.<br /><br />Just a theory (hypothesis, idea, etc.), btw.

 

[search]

Read trhough this. Maybe it helps understanding pros and cons of MOND <br /><br />http://en.wikipedia.org/wiki/MOND#Consistency_with_the_observations

 

[eso44527]

The MOND pages do a nice job of overviewing MOND. There is also a section of comments responding to the recent Bullet Cluster results that have been claimed to falsify MOND.

 

[nojocujo]

MOND might be dead. Mond was an alternative for CDM. Which was cold dark matter in light of recent observations in might be collisionless dark matter.

 

[eso44527]

Unfortunately for CDM enthusiasts galaxy scale observations contradict the notion of collisionless DM. This is a very interesting paradox. They claim from the Bullet cluster that there must be CDM, but they are forgetting about the overwhelming evidence on galaxy scales which shows that the inferred DM is coupled to the distribution of baryonic matter - an impossible trait for collsionless CDM. So on galaxy scales CDM has been falsified.

 

[observer7]

Thanks for the inforamtion and links.<br /><br />Based on what I was able to review the idea that I had seems to be a variation of MOND that is closer to GR.<br /><br />Here is the general idea.<br /><br />Gravity is described as the curvature of space-time. With this in mind I envision several scales of curvature. First, the scale of things we are familiar with and can observe. From grains of sand to stars and planets, we observe gravity acting in a particular way that is described by Newtonian theory. Einsteins GR provides a better description and accounts for things like the precession of Mercury better then strictly Newtonian theory.<br /><br />In this same light, we can consider a larger scale where galaxys create additional curvature in space-time. This allows the stars in the galaxy to be bound to each other more like a liquid or solid and orbit the galaxy center together. The galaxy behaves like a solidd planet, tightly bound together. We don't expect the outer regions of a planet to rotate at different rates (other then the difference due to the greater circumference they have to follow) because of gravity.<br /><br />Picture the classic description of space-time as a stretched net with balls representing masses. In the classic interpretation we add the separate indents (stars) of each mass together and claim this is the mass of the combined heap (galaxy). I see the indivdual indents embedded in a larger indent caused by the large scale curvature of space-time. Net result, it looks like there is more gravity then can be accounted for by the individual masses.<br /><br />I think the large scale curvatue is a function of mass. Larger masses (like galaxies) start to show this effect. I do not have the math skills to even guess at the nature of this function but I look to someone here to give me a guess. I looked at some of the alternate theories and this seems to be a defensible idea. On even larger scales it could curve the entire universe enough to accout <div class="Discussion_UserSignature"> <em><font size="2">"Time exists so that everything doesn't happen at once" </font></em><font size="2">Albert Einstein</font> </div>

 

[Kalstang]

<blockquote><font class="small">In reply to:</font><hr /><p>Saying there is no dark matter is rejecting a very valid theory. Even the dark matter theorist do not reject (or should not) the contender theories.<p><hr /></p></p></blockquote><br /><br />And yet the theories of ET's visiting Earth are continually being shot down because there's no physical evidence. Just like theres no physical evidence of Dark Matter. Yet Dark Matter is more accepted?....hrmm seems a bit hipocritical to me.....<br /><br />Disclaimer: I believe in both ET's visiting Earth AND Dark Matter. Was just makeing an observation is all. <div class="Discussion_UserSignature"> <font color="#ffff00"><p><font color="#3366ff">I have an answer for everything...you may not like the answer or it may not satisfy your curiosity..but it will still be an answer.</font> <br /><font color="#ff0000">"Imagination is more important then Knowledge" ~Albert Einstien~</font> <br /><font color="#cc99ff">Guns dont kill people. People kill people</font>.</p></font><p><font color="#ff6600">Solar System</font></p> </div>

 

[search]

Clarification:<br /><br />Dark matter: <br />"Physical objects or particles that emit little or no detectable radiation of their own and are postulated to exist because of unexplained gravitational forces observed on other astronomical objects. Dark matter is believed to be part of the missing mass."<br /><br />Dark matter existence: <br />Still not found. Effects have been detected. There are other theories to explain those effects (like MOND) and scientists are grouped in different fronts to find out what is really happening. Most of the times it is a collaborative effort. Sometimes it is percieved as fight between them. <br /><br />ET: <br />An extraterrestrial being or life form.<br /><br />ET existence: <br />Some claim to have met them and that they have visited earth. Scientists do not (in general) deny their existence. They tend to challenge the earth visits as this would imply travelling imense distances and (according with our actual knowledge and thechnology) that would take years, centuries if not milleniums. <br /><br />There is actual theories relating cosmology to extra terrestrial visits so there is space for all in science:<br />http://www.ufoskeptic.org/JBIS.pdf#search="Extra%20Terrestrial%20theories"<br /><br />In my own humble opinion (IMOHO):<br />I believe that there is either 'dark matter" (it is an unfortunate name in scientifical terms, although very trendy-scientists percieved already that they need to attract common people through the media) or the formulations and laws are compromised and carry an inner miscalculation or misinterpretation of the reality. It is easier that the laws are wrong than the mathematics because it is easier to check and correct mathematics. Laws require more extensive prove. However the next years will surely give a great insight on either of this.<br /> <br />I believe in extra terrestrial life in diverse biological forms and shape

 

[Kalstang]

<blockquote><font class="small">In reply to:</font><hr /><p>I would, however, not compare the case of dark matter to the case of ET's. <p><hr /></p></p></blockquote><br /><br />Why not? They both are talked about by observers/interested parties. They both have valid theories. They both have no physical proof. Yet the theory of ET's visiting Earth is scoffed at far more then the exsistence of Dark Matter. I've read the report you linked several times before. It seems to be the one that proponnets of ET's visiting us use more then anything else to prove that its possible for them to travel here even over immense distances. <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Scientists do not (in general) deny their existence.<p><hr /></p></p></blockquote><br /><br />True scientists shouldn't. The ones that do are more concerned about thier reputation then the actual science. <div class="Discussion_UserSignature"> <font color="#ffff00"><p><font color="#3366ff">I have an answer for everything...you may not like the answer or it may not satisfy your curiosity..but it will still be an answer.</font> <br /><font color="#ff0000">"Imagination is more important then Knowledge" ~Albert Einstien~</font> <br /><font color="#cc99ff">Guns dont kill people. People kill people</font>.</p></font><p><font color="#ff6600">Solar System</font></p> </div>

 

[search]

I said: "I wouldn't" it does not mean others wouldn't. It is a preference I have.<br /><br />I agree on the second one (although not all care so much about reputation as they care about true science).