New Celestia-1.4.0pre-FT1 (galaxies) for Testing

[Toti]

Well, I used some "vectorizing code" written by Toti , (after
eliminating some nasty buggies). This simple command-line tool
has it's "own will" somehow, but after practicing enough, the
results are quite neat.

That tool was only meant to build testing templates, it's too difficult to manage well.
I recently implemented a much more sophisticated version which behaves reliably.

[t00fri]

Well, I used some "vectorizing code" written by Toti , (after
eliminating some nasty buggies). This simple command-line tool
has it's "own will" somehow, but after practicing enough, the
results are quite neat.

That tool was only meant to build testing templates, it's too difficult to manage well.
I recently implemented a much more sophisticated version which behaves reliably.

Good I find out about it this way

Bye Fridger

[ElChristou]

...I recently implemented a much more sophisticated version which behaves reliably.

Very good!! a tool like this will be amazing to create artistic interpretation...

[Toti]

Good I find out about it this way

Ha!
It outputs in a completely different format (which I still have to polish a lot) that is incompatible with .pts and thus useless for FT1.1
Works well but it's under heavy development: I'll send you a working version ASAP.

BTW: "recently" is last week

[t00fri]

Good I find out about it this way

Ha!
It outputs in a completely different format (which I still have to polish a lot) that is incompatible with .pts and thus useless for FT1.1
Works well but it's under heavy development: I'll send you a working version ASAP.

Now that I am a "master" in handling 'bmp2pts', I do find that tool quite capaple and the present FT1 .pts templates also could be worse I think . After the parameter settings finally worked...of course

Bye Fridger

[t00fri]

Cham,

well, whatever you are implicitly referring to, the only SERIOUS competitor to DarkMatter is the socalled MOND =MOdified Newtonian Dynamics paradym (1983-84) and modern versions thereoff (Nima Arkani-Hamed et al, Harvard) .

Bye Fridger

No, apparently, there are some misconceptions along the astronomers. Gravitomagnetism may be very strong, at large scales. Classical general relativity may explain the rotation curves, but only if we retains some non-linearities related to gravitomagnetism, in the field equation. Apparently, it isn't a very well known subject, and astronomers tend to be non-rigorous enough with GR. I'm trying to find the articles I've read on this.

cham,

you were actually right. The relevant paper is quite new

http://xxx.lanl.gov/abs/astro-ph/0507619

By using general relativity instead of Newtonian gravity, Cooperstock and Tieu find no need for Dark Matter to explain the observed rotation curves of galaxies. This is because even for weak fields and slow speeds, well-known non-linearities change the /character/ of the solution dramatically. The success of Newtonian mechanics in situations like our solar system can be traced to the fact that in this case the planets are basically "test particles", which do not contribute significantly to the overall field. However in a galaxy this approximation is not a good one -- all the rotating matter is also the /source/ of the gravitational field in which everything rotates!!

So quite along the lines you remembered.

Looks interesting, indeed.

Bye Fridger

PS: In case you care to answer, let's continue in the DarkMatter thread in Physics&Astronomy...

[cartrite]

Hi Fridger,

Question, Is there going to be a way to dimm the galaxies in the new ft-1 version? The images below shows an addon of m31 I'm working on and m31 rendererd by ft-1( 1st, galaxies and nebula on, and 2nd, galaxies off). I thought they would look better together if I could make the renderd m31 dimmer.

[img][img]http://img375.imageshack.us/img375/9365/m31frommarsorbit4bothon9te.th.jpg[/img]
[img][img]http://img226.imageshack.us/img226/4056/m31frommarsorbit48er.th.jpg[/img][/img]

Later,

cartrite

[buggs_moran]

Cartrite,

I believe it is Shift - ( and Shift - )

Buggs

[t00fri]

Hi Fridger,

Question, Is there going to be a way to dimm the galaxies in the new ft-1 version? The images below shows an addon of m31 I'm working on and m31 rendererd by ft-1( 1st, galaxies and nebula on, and 2nd, galaxies off). I thought they would look better together if I could make the renderd m31 dimmer.

[img][img]http://img375.imageshack.us/img375/9365/m31frommarsorbit4bothon9te.th.jpg[/img]
[img][img]http://img226.imageshack.us/img226/4056/m31frommarsorbit48er.th.jpg[/img][/img]

Later,

cartrite

Cartrite,

right now galaxies can only be made brighter then the default. The reason is that a lot of effort went in to come up with a consistent relative brightness scheme. Since the responses are non-linear the relation would be destroyed at much different base-brightness levels.

Did you consider normalizing brightness and contrast correctly for your monitir, by using specialized software?

If more people want to turn down brightness, it is of course utterly trivial to do it in the code...

Bye Fridger

[cartrite]

I didn't know that there was software available to that but I'm not sure if you understood what I was asking. I was looking for a way to dimm (an option) the galaxy drawn by celestia not the whole monitor. So with both the galaxy and nebulae options on, the addons would be shown together, complimenting each other. The pic below may show what I mean by dimming the galaxy. Anyhow it's no big deal. I was just looking for a way to surround the m31 addon I'm working on with a gas and dust cloud.
[/img]

of course this is with faintest stars at the max (15)

cartrite

[t00fri]

I didn't know that there was software available to that but I'm not sure if you understood what I was asking. I was looking for a way to dimm (an option) the galaxy drawn by celestia not the whole monitor. So with both the galaxy and nebulae options on, the addons would be shown together, complimenting each other. The pic below may show what I mean by dimming the galaxy. Anyhow it's no big deal. I was just looking for a way to surround the m31 addon I'm working on with a gas and dust cloud.
[/img]

of course this is with faintest stars at the max (15)

cartrite

Sure I understood, but still the general appearance of galaxies may look quite different with different gamma profiles etc. Perhaps in such a case you would not want to apply any further /individual/ dimming...

Certainly I would not see much /general/ interest to allow for brightness adjustments of each galaxy /individually/. That would sabotage the whole underlying idea of a correct /relative/ brightness representation of deep sky objects. We can hardly attach knobs to each DSO displayed on the screen.

Anything we incorporate as an extra should first be supported my a major class of possible applications, in which obviously a number of people would be strongly interested.

Then it would probably be better if you just turn down by hand the respective AbsMag value in deepsky.dsc. You can always do that since with your planned modifications you lose anyway the connection to realistic rendering.

Bye Fridger

[cartrite]

Ah, The AbsMag value. Seems about a couple of weeks ago I was playing with that value to get my extra m31 to appear in FT1. Didn't know that it controlled the brightness of the rendered galaxy. Thanks Fridger.

cartrite

[wcomer]

Fridger+Cham,

Here is a rebuttal paper:

"Recently a new model of galactic gravitational field, based on ordinary General Relativity, has been proposed by Cooperstock and Tieu in which no exotic dark matter is needed to fit the observed rotation curve to a reasonable ordinary matter distribution. We argue that in this model the gravitational field is generated not only by the galaxy matter, but by a thin, singular disk as well. The model should therefore be considered unphysical."

http://xxx.lanl.gov/abs/astro-ph/0508377

thoughts?
-Walton

[Cham]

Fridger+Cham,

Here is a rebuttal paper:

"Recently a new model of galactic gravitational field, based on ordinary General Relativity, has been proposed by Cooperstock and Tieu in which no exotic dark matter is needed to fit the observed rotation curve to a reasonable ordinary matter distribution. We argue that in this model the gravitational field is generated not only by the galaxy matter, but by a thin, singular disk as well. The model should therefore be considered unphysical."

http://xxx.lanl.gov/abs/astro-ph/0508377

thoughts?

-Walton

Interesting, thanks to share that info.

But don't worry, there will be a rebuttal paper on the rebuttal itself !


And it's all about a **model**, not a totally accurate theory. Even if the details are not right, I have full confidence in General Relativity. Like Einstein said himself : the theory is correct ! And I don't believe in Dark Matter ! However, I strongly believe in ignorance and confusion of the astronomers !!

Subtle is the lord, but malicious he is not.



EDIT: I just have read that rebuttal article (5 pages). In my opinion, that rebuttal is badly written, statements are formulated in a very sloppy fashion, and there are some typographical errors. I have seen much better before, about rebuttals.

You know, Dark Matter is a very "fashion" subject today. There are LOTS of people working on this right now. The article from Cooperstock and Tieu is on the reverse way. So I can understand that many researchers may react negatively. If Cooperstock and Tieu are right (despite some weakness in their arguments), then it would mean that a lot of people are losing their precious time working on a "futile" subject as Dark Matter !

[t00fri]

I suppose you saw my citation of the Cooperstock and Tieu paper a few posts higher up...

I don't find the rebuttal paper all that convincing.

Bye Fridger

[Cham]

I suppose you saw my citation of the Cooperstock and Tieu paper a few posts higher up...

I don't find the rebuttal paper all that convincing.

Bye Fridger

Yes, I saw your post. The rebuttal isn't convincing at all, it's too much badly wrtten for my taste.

We could continue on this subject to the Physics&Astronomy forum, but really, I don't have much to say, except maybe that I'm always impressed by all the BS and nonsenses I read everywhere in books and magazines about cosmology, light travel time, etc. I get very demoralized after some times. Education isn't doing its job.

[wcomer]

Fridger+Cham,

Thanks for the insight. I read some pretty nasty comments on the Cooperstock and Tieu in another physics forum, so I thought I throw the 'rebuttal' at you two and see what you thought. I'm certainly not qualified to judge it myself. But I have high regard for your opinions.

cheers,
Walton

[t00fri]

Fridger+Cham,

Thanks for the insight. I read some pretty nasty comments on the Cooperstock and Tieu in another physics forum, so I thought I throw the 'rebuttal' at you two and see what you thought. I'm certainly not qualified to judge it myself. But I have high regard for your opinions.

cheers,
Walton

The paper by Cooperstock & Tieu got a feature article in the "CERN Courier", the official journal of the world's biggest laboratory in particle physics in Geneva. For such reviews they would typically ask outstanding capacities in the field!

It also implies that at the CERN Theory department there was plenty of rather positive discussion about that paper. I know CERN very well, since I have been a staff member in its theoretical physics department for 7 years.

Bye Fridger

[wcomer]

If this paper stands, why do you suppose it has taken so long for anyone to discover this? I assume all the theory and techniques involved have been well understood for many decades - is this not the case?

-Walton

[Cham]

If this paper stands, why do you suppose it has taken so long for anyone to discover this? I assume all the theory and techniques involved have been well understood for many decades - is this not the case?

-Walton

Yes, it was (partly) known since Heddington's times ! But apparently, most astronomers don't know General Relativity very well. They had a single introductory course in GR, and they assume Newton's gravitation theory applies to everything, if gravity is "weak". Which is false !

If the new finding gets confirmed, it will become a very important new test for General Relativity. Personally, I think it's a major subject and I'll be watching every info on this.