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Author Topic: Does dark matter really exsist  (Read 8076 times)

Offline Eric A. Taylor

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Does dark matter really exsist
« on: 03/11/2009 14:42:45 »
The 19th century saw huge advances in science. However there were rather large problems.

Light (electromagnetism) was known to be a wave. Physicists knew that all waves needed a medium through which they could propagate. To explain how light passed through seemingly empty space physicists made up something called luminiferous aether. It proved incredibly hard to detect because it didn't interact with matter. It could not be detected by sensors made of matter.

The other problem in physics was orbital anomalies in Mercury's orbit. To explain them it was suggested that an undiscovered planet lay closer to the sun inside the orbit of Mercury. This planet also proved very difficult to detect.

Both of these problems were solved by Relativity. You could say that Albert Einstein "discovered" this unknown planet and luminiferous aether by presenting a theory that showed they didn't exist.

You would think science would learn a lesson here: Don't make stuff up to make your theory jive with observation. Yet cosmologist have made up dark matter and dark energy to make anomalies jive with modern theories of gravity. So which is more likely? 95% of the universe is made of some unknown, undetectable matter that does not interact with light but does interact with normal matter through gravity, or that out theories of gravity are inaccurate and extremely large scales.

We know that Relativity and/or Quantum Theory are not quite accurate because they break down when combined. This is a huge problem. Imagine a city in which all the passenger cars stop at red lights and proceed at green lights, while all the trucks stop on green and go on red. This arrangement would not be a problem so long as the trucks and cars stayed in separate parts of town. But where cars and trucks meet in the middle you're going to have crashes.

If a theory does not match observation it must be wrong.


 

Offline Vern

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« Reply #1 on: 03/11/2009 15:22:40 »
I think the speculations about dark matter are still speculations; there's something going on but nobody has pinned it down exactly. All of the speculations are interesting. I don't know of a speculative idea that exactly matches all the observations.
 

Offline graham.d

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« Reply #2 on: 03/11/2009 17:42:28 »
I agree, there is a lot of speculative ideas on these subjects but, to a large extent, this is the way developments come about: people come up with theories and then these have to be disproved by observation. The concepts regarding dark matter and dark energy (really two concepts), Dark Energy would form 72% of the universe and Dark Matter 23%. The dark matter idea comes from observations of galaxies whereas the dark energy idea comes from recent estimations of the rate of expansion of the universe. The relative numbers come from tying the two effects together.

There are plenty of other theories which try to explain the observations, including many that modify QM and GR, but I have a suspician they are not any more palatable than these ones.
 

Offline litespeed

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« Reply #3 on: 03/11/2009 17:57:59 »
Vern,

I like the rule-of-thumb-law that a simplesr explanation already has an advantage. I think it is entirely possible all that missing matter is simply regular matter that does not luminesce.  Think of a planetary system that forms around a failed star.  I suspect LOTS of cosmic acreation discs form without the required critical mass to make for the central gas giant to ignite.

Further, we seem to believe the early universe produced a larger proporton of red giants then is the case to day. If that is the case, VERY large numbers of 'lower mass' black holes could be residual all over the place.
 

Offline graham.d

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« Reply #4 on: 04/11/2009 10:12:33 »
I believe that the reason for the suggestion of dark matter as something distinct from non-lumenescent bodies is that the rotation of galaxies and the virial theorem implies that there is a fairly even mass distribution of such matter within galaxies. The amount of extra mass (23%) is such that it is not thought likely that we would not have detected it if in the form of solid bodies (even if dark). Also, there is no model of star formation that would also suggest that such bodies would have formed to this extent. Although this apparently simple solution may well prove to be right, it is probably not correct to suggest that this concept has been rejected in favour of a more exotic one out of perversity. The truth is that we have not got any solution that fits all the observations or existing theory.
 

Offline LeeE

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« Reply #5 on: 04/11/2009 10:20:57 »
I'm broadly in agreement with the other posters; there seems to be an anomaly that we can't currently explain definitively.

Also, as the others point out, there's a pretty wide range of possible answers, ranging from the exotic to the prosaic, that explain most of the observed phenomenon, but not all of them.

In the end, we know that our current theories are inadequate.  It may be because they're fundamentally incorrect, but it is more likely that, in view of how large parts of our theories do work, and work well, our theories are just incomplete and that eventually we'll fill in the gaps.
 

Offline Don_1

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« Reply #6 on: 04/11/2009 10:54:20 »
There was a good programme on the BBC about black holes last night.

If you missed it, its on the iplayer here http://www.bbc.co.uk/iplayer/episode/b00nslc4/Horizon_20092010_Whos_Afraid_of_a_Big_Black_Hole/

I'm not sure if this can be viewed outside the UK.
 

Offline LeeE

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« Reply #7 on: 04/11/2009 12:04:51 »
Thanks for the link - I'll have a look.

The problem I find with science documentaries that try to deal with 'extreme' physics is that the majority of the intended audience just isn't familiar enough with some of the concepts involved to be able to understand them properly so the subject has to be 'dumbed down' to the point where they become inaccurate and sometimes even misleading.  Dunno the solution to this though :(

One of the strange consequences of this is that when I'm watching science programs, usually with my parents when I visit them (they know I don't have a TV and give me the remote control), I end up repeatedly criticising many of the statements made in the programmes even though I agree with the underlying science.  Oh well...
 

Offline Vern

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« Reply #8 on: 04/11/2009 12:16:37 »
Quote from: litespeed
Further, we seem to believe the early universe produced a larger proporton of red giants then is the case to day. If that is the case, VERY large numbers of 'lower mass' black holes could be residual all over the place.

Your notion becomes more probable if more time is allowed for burnt out dark stars to form. But then there is the question of why don't we see the dark objects blocking more distant light?
 

Offline that mad man

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« Reply #9 on: 04/11/2009 16:08:32 »
There was a good programme on the BBC about black holes last night.

If you missed it, its on the iplayer here http://www.bbc.co.uk/iplayer/episode/b00nslc4/Horizon_20092010_Whos_Afraid_of_a_Big_Black_Hole/

I'm not sure if this can be viewed outside the UK.

Caught it, and yes it was good. The conclusion was scientists just don't know what black holes are made of as none has yet been observed directly.

 

Offline Mr. Scientist

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« Reply #10 on: 04/11/2009 16:12:58 »
There was a good programme on the BBC about black holes last night.

If you missed it, its on the iplayer here http://www.bbc.co.uk/iplayer/episode/b00nslc4/Horizon_20092010_Whos_Afraid_of_a_Big_Black_Hole/

I'm not sure if this can be viewed outside the UK.

Caught it, and yes it was good. The conclusion was scientists just don't know what black holes are made of as none has yet been observed directly.



That would also mean, following the same logic, we don't know if black holes are real or not, since they have not been varified-observationally.
 

Offline Vern

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« Reply #11 on: 04/11/2009 16:51:39 »
Quote from: Mr. Scientist
That would also mean, following the same logic, we don't know if black holes are real or not, since they have not been varified-observationally.

I am very suspicious of the notion that Black Holes can exist. I have tried to write a computer simulation of both scenarios, spinning and straight line collapse, and neither work when I include relativity phenomena in the algorithm. The problem is that acceleration contains time as an element and time is gravity dependant. So the program can never reach a gravitational singularity. Said simply; gravity affects gravity, diminishing gravities effect as gravity increases.

In electronics, we call that negative feedback. And; I wonder if this negative feedback might have something to do with the rotational anomalies we observe in galaxies. :)

« Last Edit: 04/11/2009 20:24:52 by Vern »
 

Offline graham.d

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« Reply #12 on: 04/11/2009 17:07:51 »
I intended to watch the Horizon programme but the problem with Horizon is that it invariably sends me to sleep. I had also had a couple of beers which made me think I would never get through it. As it's been recommended I will view it on Iplayer. Am I alone in thinking that Horizon pitches its presentation so that if you know about a subject, it is 90% imagery with no significant content, and if you don't know anything about the subject it is hard to discern the useful stuff from the dross. Either way => sleep (at least for me).
 

Offline Mr. Scientist

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« Reply #13 on: 04/11/2009 17:10:36 »
Quote from: Mr. Scientist
That would also mean, following the same logic, we don't know if black holes are real or not, since they have not been varified-observationally.

I am very suspicious of the notion that Black Holes can exist. I have tried to write a computer simulation of both scenarios, spinning and straight line collapse, and neither work when I include relativity phenomena in the algorithm. The problem is that acceleration contains time as an element and time is gravity dependant. So the program can never reach a gravitational singularity. Said simply; gravity affects gravity diminishing its effect as it increases.

In electronics, we call that negative feedback. And; I wonder if this negative feedback might have something to do with the rotational anomalies we observe in galaxies. :)



Interesting hypothesis.
 

Offline Vern

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« Reply #14 on: 05/11/2009 13:43:07 »
The more I think about the rotational anomalies of galaxies in light of recent posts in this forum, the more I realize that there are probably multiple causes. Several candidates identified are:

Burnt out neutron stars
Remnants of galactic parental accretion material
Gravitational effects upon gravity itself; negative feedback
Spewed out star dust from billions of years of galactic star life

It seems to me that all of these things should have some effect upon orbital speeds of individual stars within a galaxy. The least likely probability is that there is some unknown kind of dark matter. Of course, we could just associate the term "dark matter" with all of the list and save the dark matter hypothesis.


Edit: If it is true that the above list of things contribute to the galactic orbital anomaly, then the degree of orbital anomaly might be a measure of the age of a galaxy.
« Last Edit: 05/11/2009 17:14:01 by Vern »
 

Offline litespeed

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« Reply #15 on: 05/11/2009 18:22:01 »
LeeE - You wrote: "The problem I find with science documentaries ...[is they are] 'dumbed down' to the point where they become inaccurate and sometimes even misleading."

I actually think this is an advantage to those of us who know just enough to be dangerous. Almost every one of these science shows seem to miss something very important, or get something very wrong, in addition to being very informative.

In fact, I find my self replaying many of then in order to accumulate areas to investigate further.  One big example is I have never seen a discussion of whether a Neutron Star can become a BH though simple mass accretion.
 

Offline litespeed

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« Reply #16 on: 05/11/2009 18:31:59 »
Vern

I think you are very much on the right track. Everything entering a black hole accelerates to relativistic levels, thus complicating the entire description endlessly.

My own conclusion is BHS are nothing more then ordinary mass accumulations that have both mass and velocity sufficient to bring the contents to a near time stop as they approach the center. In fact, there could actually be some sort of non relativistic mass at the center such as a neutron star.

That neutron star would have been created in the initial supernova explosion. That central object then gravitationally re-attracts much of the expanding matter that has been spread far and wide.  If enough of that matter is far enough away to achieve relativistic velocities upon returning, you might end up with something like a neutron star at the center, with a shell of matter comming to a near stop from time and mass dialation.
 

Offline Vern

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« Reply #17 on: 05/11/2009 19:27:34 »
Looks like we'll have to forgo the Nobel for our discovery :) Someone else beat us to it. But it seems they cite a different mechanism. I wonder why no one seems to have tried a computer model of a forming Black Hole taking into account relativity phenomena.

Quote from: the link
They find that the gravity of the collapsing mass starts to disrupt the quantum vacuum, generating what they call "pre-Hawking" radiation. Losing that radiation reduces the total mass-energy of the object - so that it never gets dense enough to form an event horizon and a true black hole. "There are no such things", Vachaspati told New Scientist. "There are only stars going toward being a black hole but not getting there."
« Last Edit: 05/11/2009 19:29:49 by Vern »
 

Offline litespeed

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« Reply #18 on: 05/11/2009 20:23:23 »
Vern

"There are no such things", Vachaspati told New Scientist. "There are only stars going toward being a black hole but not getting there."

I think we can we might still wrangle up that Nobel. I believe there are locations in space where gravity, mass, and relativistic speeds prevent luminescense. Sounds like a damned black hole to me. We should ask Vachaspati to provide a photograph of one of his stars that is not quite getting there.

 

Offline litespeed

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« Reply #19 on: 05/11/2009 20:33:27 »
Vern

PS: Sadly, I doubt anyone would get a Nobel by showing nothing out of the ordinary is going on in these BH areas.
 

Offline Vern

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« Reply #20 on: 05/11/2009 20:37:48 »
We will have to put some numbers to our mechanism. Lets see; the mechanism is that acceleration contains time as an element; matter must accelerate to fall in; as gravity increases, time slows; as time slows, acceleration slows, and at some point the matter is not moving any more. :)

It is hard to get my mind around that; we know there is some super massive thing at the centre of galaxies. Now if we apply our gravity damping mechanism to the galactic centre we may be able to predict the orbital anomalies we observe.

 

Offline Vern

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« Reply #21 on: 05/11/2009 20:38:27 »
Vern

PS: Sadly, I doubt anyone would get a Nobel by showing nothing out of the ordinary is going on in these BH areas.
Yep; I was just kidding of course. :) I suspect they have stopped giving the Nobel for real achievements. It seems more of a political tool now.
« Last Edit: 05/11/2009 20:40:32 by Vern »
 

Offline litespeed

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« Reply #22 on: 05/11/2009 20:45:56 »
Vern

I nominate President Obama to accept our award and donate the proceeds to Acorn on a one to one matching basis from Soros!
 

Offline Vern

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« Reply #23 on: 05/11/2009 20:48:02 »
I just thought of another mechanism that might contribute to the decrease in gravity. The almost-black-hole at the galactic centre could be spinning so that its rim is at near light speed. Relativity kicks in and our gravity reducing mechanism has another contributor. We have gravitational negative feed back and speed induced relativity helping to reduce gravity.
 

Offline Vern

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« Reply #24 on: 05/11/2009 20:48:32 »
Vern

I nominate President Obama to accept our award and donate the proceeds to Acorn on a one to one matching basis from Soros!

Hey; I like that; good idea !!
 

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