Plasma Cosmology - Woo or not

[DeiRenDopa]

I am not sure, but there may exist a common "galactic radius", beyond which the rotation curve flattens out. You know, some relationship between that point and the total mass of the galaxy, for example.

Interesting idea ...

There may well be several hundred, to several thousand, papers on this topic, and IIRC at least one Universal Rotation Curve (or similar name) has been proposed.

However, also IIRC, it'd be quite a stretch to say the data (which is now into the tens of thousands of good observations) are consistent with your idea, as expressed.

I just wanted to make the point that TT did not have any qualifiers in his discussion of star orbits. Not every star orbit in the universe requires "dark matter" to explain.

Quite.

But perhaps then you are hoist on your own petard?

By conflating "stellar orbits" and "rotation curve" perhaps?

After all, not every galaxy has a "rotation curve", does it?

As far as Peratt's model, I am not sure. If I had to conjecture, I would say that there was some constant EM field extending throughout the galaxy, and for large radius orbits, it would tend to add velocity over and beyond what could be expected from gravity alone. Of course, there are myriad other problems with a supposition such as this. I'm not qualified to pinch-hit for Zeeeuuuuussssss.

Fair enough.

Nothing to do with galaxy rotation curves then? And we can get back to our regular programme?

 

[DeiRenDopa]

Wangler: I read somewhere that the accepted magnetic field of the galaxy could account for about 10% of the stellar velocity discrepancy at large galactic radii.

You don't happen to have the reference to hand do you?

Without it I can't be sure, but I suspect you may have mis-read, misunderstood, or mis-remembered ...

 

[Tubbythin]

I just wanted to make the point that TT did not have any qualifiers in his discussion of star orbits. Not every star orbit in the universe requires "dark matter" to explain.

I was responding to Zeuzzz's response about how PC explained galactic rotation curves. Whether some orbits can be explained with gravity without DM seems somewhat irrelevant. The point was that if Perratt's model uses our current law of gravity without DM to explain rotation curves, then it fails.

 

[Reality Check]

I was responding to Zeuzzz's response about how PC explained galactic rotation curves. Whether some orbits can be explained with gravity without DM seems somewhat irrelevant. The point was that if Perratt's model uses our current law of gravity without DM to explain rotation curves, then it fails.

Peratt's model then really, really fails since it does not use gravity at all. The software used to produce his maps of plasma density was plasma simulation software.

 

[Dancing David]

DD,

I agree that stars in galactic orbits of sufficiently large radius do not rotate as slow as they should.

Stars closer to the galactic bulge follow a Keplerian drop off quite nicely.

Which is why the model have the DM distributed in the halo, right?

I could be wrong.

Star clusters, I am not sure of. Are you taking about globulars, or galactic clusters? Any references or further information?

The clusters in the halo of the MW, I have assumed that they show the rotational acceleration of gravity+DM, otherwise it would be a huge hole in the theory.

Most of the research seems to be in formation of the clusters and not in their apparent motions.

 

[NoisyAstronomer]

I read somewhere that the accepted magnetic field of the galaxy could account for about 10% of the stellar velocity discrepancy at large galactic radii.
.

Eh?? How does a magnetic field disturb a massive neutral object? That makes no sense. Magnetic fields in the galaxy are responsible for large scale movement of ions, creating what we call "cosmic rays", which are charged particles that are accelerated to very high speeds. But a star is a massive, neutral object that is only easily deflected by the gravitational tug of mass around it.

Anyway, the wikipedia article on galactic rotation curves does a nice job of summarizing the problem, and how it is only one indicator of dark matter. Also important are galaxy velocities within clusters and its role in the concordance model of cosmology. It even discusses dark matter's only good contender, which is MOND, although that has fallen into serious trouble thanks to new evidence.

One day soon, we should be able to detect dark matter directly for the first time! I'm anxiously awaiting results of GLAST... sorry, now Fermi!

 

[sol invictus]

Eh?? How does a magnetic field disturb a massive neutral object? That makes no sense.

We had a long discussion of this. Zeuzzz was shown how totally absurd the idea is - you'd need such a huge charge on the star that it would instantly explode from electrostatic repulsion, for one thing. That doesn't seem to have any effect on his faith, though, and he now seems to have conveniently forgotten all about it.

 

[NoisyAstronomer]

...you'd need such a huge charge on the star that it would instantly explode from electrostatic repulsion...

Huge explosion? If it were true, the Mythbusters would do it!!

(Sorry, still high from the Moon Hoax episode.)

It's amazing. Dark matter had it's decades of being treated very suspiciously by the astronomical community. Now with the mountains of evidence in its favor, it's clearly a conspiracy!!!11!!!11

*Sigh*

 

[Wangler]

Wangler: I read somewhere that the accepted magnetic field of the galaxy could account for about 10% of the stellar velocity discrepancy at large galactic radii.

You don't happen to have the reference to hand do you?

Without it I can't be sure, but I suspect you may have mis-read, misunderstood, or mis-remembered ...

I know I've given this reference twice in the time I have been posting on JREF, but I cannot search back to my very first posts (#1 thru #54, I think it's in there somewhere).

If you think I may have misunderstood, it sounds as if you think that 10% of the velocity discrepancy (from the expected rotational velocities based upon luminous matter alone) at large galactic radii is unreasonable?

Mind you, I am not saying that electromagnetism is the magic answer, but it is likely part of the correct answer........

 

[Wangler]

Eh?? How does a magnetic field disturb a massive neutral object? That makes no sense. Magnetic fields in the galaxy are responsible for large scale movement of ions, creating what we call "cosmic rays", which are charged particles that are accelerated to very high speeds. But a star is a massive, neutral object that is only easily deflected by the gravitational tug of mass around it.

Did those stars just pop into existance? Perhaps a multitude of "Small Bangs"?

I think that they were actually formed from clouds of partially charged particles. Certainly a formed star has a neutral net charge, but I think that it may be possible that the primordial cloud that the star condensed from obtained some velocity around the galaxy itself when it was disperse, and possibly charged.

 

[Wangler]

Which is why the model have the DM distributed in the halo, right?

I could be wrong.

No, you are usually right, and you are in this case (I think).

I think that the requirement for the DM halo distribution is what gives rise the the "cuspy" problem as you get close to the center of gravity of the system (the galactic core).

The clusters in the halo of the MW, I have assumed that they show the rotational acceleration of gravity+DM, otherwise it would be a huge hole in the theory.

Most of the research seems to be in formation of the clusters and not in their apparent motions.

I think I misunderstood. You are talking about motion of the cluster as a whole, not movement within the cluster. I see now.

 

[DeiRenDopa]

Wangler: I read somewhere that the accepted magnetic field of the galaxy could account for about 10% of the stellar velocity discrepancy at large galactic radii.

You don't happen to have the reference to hand do you?

Without it I can't be sure, but I suspect you may have mis-read, misunderstood, or mis-remembered ...

I know I've given this reference twice in the time I have been posting on JREF, but I cannot search back to my very first posts (#1 thru #54, I think it's in there somewhere).

Thanks for trying.

Without the reference, I can't see any way to progress this, as I'm sure you'd agree.

If you think I may have misunderstood, it sounds as if you think that 10% of the velocity discrepancy (from the expected rotational velocities based upon luminous matter alone) at large galactic radii is unreasonable?

Huh?

Can you clarify please? I can't see how "10% of the velocity discrepancy (from the expected rotational velocities based upon luminous matter alone)" has anything to do with the topic anyway! At the very least you seem to have conflated random variation about a mean with a systematic effect (the solar system has a well-established motion with respect to the local standard of rest, for example).

Mind you, I am not saying that electromagnetism is the magic answer, but it is likely part of the correct answer........

Perhaps.

I'd like to understand the question first, before trying to come to grips with any potential answers, if you don't mind.

 

[sol invictus]

I read somewhere that the accepted magnetic field of the galaxy could account for about 10% of the stellar velocity discrepancy at large galactic radii.

So, a field about 10 times as large as commonly accepted would do nicely.

I know I've given this reference twice in the time I have been posting on JREF, but I cannot search back to my very first posts (#1 thru #54, I think it's in there somewhere).

Let's see...

I have seen published estimates that galactic electromagnetic fields can account for approximately 10% of the galactic rotational discrepancy at large radii.

I was mistaken, I was confusing 10% with 10 km/sec velocity due to galactic magnetic fields.

See my post here for the references (they determine 10 to 20 km/sec rotation velocity may be due to magnetic fields).

http://www.internationalskeptics.com/forums/showthread.php?p=3592547#post3592547

This effect is certainly larger than 10^22 of gravity, I think.

Sorry for being incorrect in my memory, though.

Your memory doesn't seem to have improved since April, since you made the same mistake again here.

More importantly your references don't say what you say they say... from the first:

For magnetic effects to occur the gas must be partially ionized.

and the second:

...the orbits of Galactic globular clusters,
the satellite galaxies and possibly the dynamics of remote
stars in the outer Galactic halo, which are not affected
by magnetic fields, strongly argue in favor of a dark halo
around the Milky Way.

They are talking about ionized gas. We were talking about stars.

 

[Dancing David]

Did those stars just pop into existance? Perhaps a multitude of "Small Bangs"?

I think that they were actually formed from clouds of partially charged particles. Certainly a formed star has a neutral net charge, but I think that it may be possible that the primordial cloud that the star condensed from obtained some velocity around the galaxy itself when it was disperse, and possibly charged.

This would not explain the current velocity past that of gravity-DM.

 

[Reality Check]

Did those stars just pop into existance? Perhaps a multitude of "Small Bangs"?

Definitely not - normal and well known astronomical processes formed stars. No cosmology needed.

I think that they were actually formed from clouds of partially charged particles. Certainly a formed star has a neutral net charge, but I think that it may be possible that the primordial cloud that the star condensed from obtained some velocity around the galaxy itself when it was disperse, and possibly charged.

I am not sure what stars your are talking about (stars in general?). You are correct that the gas cloud that a star formed from might be possibly charged. This would from a really odd local condition.
It would not be common and the star would quickly become electrically neutral. The conclusion from previous discussions of this is that stars are close enough to being electrically neutral so that the galactic magnetic field is many magnitudes too weak to affect them (26 orders from memory).

 

[Wangler]

Let's see...





Your memory doesn't seem to have improved since April, since you made the same mistake again here.

More importantly your references don't say what you say they say... from the first:



and the second:



They are talking about ionized gas. We were talking about stars.

Sol,

thanks for finding those..when I looked, I had 254 posts, and I could not search on any but the last 200 posts that I made. I also could not find in a general search of the forums.

Could you tell me how to find that older stuff?

 

[Wangler]

They are talking about ionized gas. We were talking about stars.

So, Sol, I am disappointed that you are the second person here who seems to think that a star's velocity cannot be dependent upon any group velocity that it's primoridal creation cloud may have had.

 

[Wangler]

Definitely not - normal and well known astronomical processes formed stars. No cosmology needed.


I am not sure what stars your are talking about (stars in general?). You are correct that the gas cloud that a star formed from might be possibly charged. This would from a really odd local condition.
It would not be common and the star would quickly become electrically neutral. The conclusion from previous discussions of this is that stars are close enough to being electrically neutral so that the galactic magnetic field is many magnitudes too weak to affect them (26 orders from memory).

I guess what I am trying to say, is the following:

IF a cloud of gas was partially ionized, and this cloud was within a EM field, it is possible that the cloud could obtain some group velocity (meaning the whole cloud has a common velocity, in a particular direction). Then, a star condenses from the moving gas cloud, retaining the common velocity.

I don't think that this would necessarily require the star to retain some net charge.

Now, it seems to me that for the star to end up neutrally charged, the cloud itself would be neutral, and wouldn't move, but I am not sure exactly.

Aren't a lot of these clouds of gas ionized? Won't that make them move under EM influences.

 

[Wangler]

Let's see...





Your memory doesn't seem to have improved since April, since you made the same mistake again here.

I was mistaken, I was confusing 10% with 10 km/sec velocity due to galactic magnetic fields.

See my post here for the references (they determine 10 to 20 km/sec rotation velocity may be due to magnetic fields).

http://www.internationalskeptics.com/forums/showthread.p...47#post3592547

This effect is certainly larger than 1022 of gravity, I think.

Sorry for being incorrect in my memory, though.

Well, here http://archive.ncsa.uiuc.edu/Cyberia/Cosmos/RotationsReckon.html

they show M31's rotation curve flatlining at about 200-220 km/s.

So 10-20 km/sec would be 5% of the rotational component, at minimum. This is making the simplistic assumption that the magnetically derived velocity is constant at those large radii where the rotation curve flattens out.

 

[DeiRenDopa]

I guess what I am trying to say, is the following:

IF a cloud of gas was partially ionized, and this cloud was within a EM field, it is possible that the cloud could obtain some group velocity (meaning the whole cloud has a common velocity, in a particular direction). Then, a star condenses from the moving gas cloud, retaining the common velocity.

I don't think that this would necessarily require the star to retain some net charge.

Now, it seems to me that for the star to end up neutrally charged, the cloud itself would be neutral, and wouldn't move, but I am not sure exactly.

Aren't a lot of these clouds of gas ionized? Won't that make them move under EM influences.

Oh dear ...

I guessed that in your earlier posts you had intended some meaning like this, but pretty much dismissed it because you'd seemed to follow the basic physics reasonably well.

Not so, it seems.

Simple analogy: if you have a weight attached to a string, and swing it round, so that it's going in a circle (more or less), what happens when you cut the string? Does the weight continue to go round in a circle?

Newton - remember him? - wrote down some 'laws of motion' a century or three ago; do you remember the one about continuing in a straight line (unless ...)?

Now once a star has condensed, from its gas+dust cloud, it's like a weight all of whose strings have been cut but one (gravity) ... how could such a star continue in its (nearly circular) orbit around the galactic nucleus?