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

[Spaceman Spiff]

Hmm, is that a cue for a Purgatory Poll Point?

At first I was a bit perplexed at symaski62's curt posts, but afetr a little thought, I realised I could begin to understand what was posted, because you see, symaski62 speaks ?„m?¶tikon(TM), the new BBwide universal language.

symaski62's last message actually says: "I say, chaps, look here! One can obtain Celestia for Windows, Linux and even Macs! Isn't that marvellous?"

And symaski62 can write French or continue with ?„m?¶tikon - fine by me!

Spiff.

[buggs_moran]

I think it's time for us, people who understand french language, to ask all of you, people who don't understand french, THE question :

Is it Ok with you if symaski62 writes ALL his messages in french ?

If you agree, and if symaski62's french is clear enough ( ), we'll translate his messages into english for you...

If you don't agree, this forum will keep a bit of its exoticism and mystery, which wouldn't be a bad thing...

Je pr?©f??re ma langue de pays. Les gens devraient se servir de leur langage s'ils ne comprennent pas des autres. Quand j'ai la difficult?© j'employez Google pour traduire d'une mani??re dont je puis comprendre.

So, I'll just speak English and leave my rusty French out of this. Sorry if the above was spotty at best, my French teacher didn't like my straight translations either, but then that was 20 years ago ... Maybe it's time to start a new thread on release of FT1.1, eh fridger. People like me keep cluttering this one with off topic posts...

http://www.google.com/language_tools

[Malenfant]

I think it's time for us, people who understand french language, to ask all of you, people who don't understand french, THE question :

Is it Ok with you if symaski62 writes ALL his messages in french ?

I'd rather he did that instead of copy/pasteing something, drawing arrows and adding smileys and leaving it to the reader to figure out what the hell he's talking about.

[jdou]

Hi Fridger and Toti,

Are you ready to modify your galaxies ?

I say that because this week I read some articles about galaxies in the french review "Science et Vie".

- The first article I read says that our Milky Way is a "spiral galaly" but seems to be a "Barred galaxy" type SBA or SBB with a narrow straigth bar on its center. More, some scientist say with perhaps a second bar in the first one
They found that with the american satellite "spitzer".

- The second article was about how was turning the galaxies :
15 astrophysicists from Nederland, Great Britain and France at the Palma observatory have tried to determinate the galaxies rotations.
For that, they used a sensor collector of light (made in France ) named "Sauron"
The results are amazing :
For example the lenticular NGC 4550 is composed of 2 stars disks.
The external disk turns in clockwise direction and the internal disk in reverse direction
NGC 4365 has also 2 disks but they run in perpendicular directions each other
etc...
So, I think your work is not finished

jdou

[t00fri]

Hi Fridger and Toti,

Are you ready to modify your galaxies ?

I say that because this week I read some articles about galaxies in the french review "Science et Vie".

- The first article I read says that our Milky Way is a "spiral galaly" but seems to be a "Barred galaxy" type SBA or SBB with a narrow straigth bar on its center. More, some scientist say with perhaps a second bar in the first one
They found that with the american satellite "spitzer".

- The second article was about how was turning the galaxies :
15 astrophysicists from Nederland, Great Britain and France at the Palma observatory have tried to determinate the galaxies rotations.
For that, they used a sensor collector of light (made in France ) named "Sauron"
The results are amazing :
For example the lenticular NGC 4550 is composed of 2 stars disks.
The external disk turns in clockwise direction and the internal disk in reverse direction
NGC 4365 has also 2 disks but they run in perpendicular directions each other
etc...
So, I think your work is not finished

jdou

Jdou,

I have implemented the appropriate barred Hubble type (SBc) into deepsky.dsc substantially before that Spitzer article started to be copied by many media. There is more solid evidence for the morphology of our galaxy than that coming recently from Spitzer. Spitzer is just boosted by the media (<=NASA) a lot for reasons easy to understand.

See my previous respective post here:
http://www.shatters.net/forum/viewtopic.php?t=7820&highlight=2mass

As to you second point, have you thought about the time scale involved in those quoted galaxy rotations ? Also whenever we start talking about rotation of galaxies we have to talk about DARK MATTER as well!

Bye Fridger

[jdou]

For the first point You are right. I should read the others topics.
I thought it was new
For the second point, as developer too, I know what these kind of movements should need to implement.
It was just some french humour

Don't forget the

Bye jdou

[t00fri]

For the first point You are right. I should read the others topics.
I thought it was new
For the second point, as developer too, I know what these kind of movements should need to implement.
It was just some french humour

Don't forget the

Bye jdou

Jdou,

I think you misunderstood my answer to your second point: with "time scale" I was not complaining that an implementation of rotation into the code would take too long. I was actually referring to the fact that rotation periods in case of galaxies are VERY long compared to what we are used to . Hence in practice it's hard to see any movement...Also one MUST have an idea about how to treat DARK MATTER if one wants to implement rotation into galaxies.

Bye Fridger

[ElChristou]

...how to treat DARK MATTER...

One day whe sholud have a serious discution on how we could represent it...

[t00fri]

...how to treat DARK MATTER...

One day whe sholud have a serious discution on how we could represent it...

As the name says, dark matter cannot be seen visually, at no wavelength! Yet since it is massive matter, it subtends gravitational interactions. The evidence for dark matter precisely came first from deviations of the rotation profiles of the luminous (i.e. visible) parts of galaxies from the known physics laws. The popular way out was to assume the presence of another form of matter, the mass of which affects the rotation profile but it is not lumninous, hence cannot be seen. There are various candidate particles (e.g. neutralinos in Supersymmetry) that could form dark matter.

There is still a small possibility that there is no dark matter at all, but rather that the laws of gravity have to be modified at such large distances ( typically from the galaxy centers to their periphery) . But this is NOT easy.

In any case, there will be NOTHING to display in Celestia . Dark matter would only affect the rotation speed of the luminous parts of galaxies that MAY be displayed in Celestia...

Bye Fridger

[Cham]

There is still a small possibility that there is no dark matter at all, but rather that the laws of gravity have to be modified at such large distances ( typically from the galaxy centers to their periphery) . But this is NOT easy.
Bye Fridger

There's also another possibility : there is no dark matter AND general relativity is badly applied by astrophysicists and astronomers. I've read that general relativity CAN actually explain the rotation curves without the need for any dark matter. The problem lies in the linear approximation used by most workers in the field. It is simply inadequate at the galactic scale. Some crucial non-linearities must be kept in the field equations in order to explain the rotation curves.

[t00fri]

There is still a small possibility that there is no dark matter at all, but rather that the laws of gravity have to be modified at such large distances ( typically from the galaxy centers to their periphery) . But this is NOT easy.
Bye Fridger

There's also another possibility : there is no dark matter AND general relativity is badly applied by astrophysicists and astronomers. I've read that general relativity CAN actually explain the rotation curves without the need for any dark matter. The problem lies in the linear approximation used by most workers in the field. It is simply inadequate at the galactic scale. Some crucial non-linearities must be kept in the field equations in order to explain the rotation curves.

Cham,

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

Bye Fridger

[Cham]

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.

[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,

there may well be articles about alternatives, yet --as I emphasized-- they are not taken seriously in the respective community. It so happened that I had dinner with last year's Nobel Prize Laureate in Particle Physics (Yes Bob, he is from MIT ) and other colleagues two days ago, where we discussed precisely this issue among world experts...

Bye Fridger

[Malenfant]

Fridger, if you don't mind I started a thread quoting your initial dark matter post on the Physics and Astronomy board - I'd like to explore that more there rather than here where it'd get lost in the other general discussion...

[abramson]

Folks,

Speaking of possible extensions of the galaxy rendering, let me share that I have been thinking of adding a pseudo realistic dust disk to the current F&T disk+bulk rendering of spirals. Perhaps it could give a realistic touch, especially when they are seen sideways. I have been reading the code, but again, with little C++ knowledge and less time, it has been uphill... Perhaps someone else...

Cheers,

Guillermo

[t00fri]

Folks,

Speaking of possible extensions of the galaxy rendering, let me share that I have been thinking of adding a pseudo realistic dust disk to the current F&T disk+bulk rendering of spirals. Perhaps it could give a realistic touch, especially when they are seen sideways. I have been reading the code, but again, with little C++ knowledge and less time, it has been uphill... Perhaps someone else...

Cheers,

Guillermo

Hi Guillermo,

I am not sure whether I understood precisely where you want to place the dust disk in case of spirals. Do you have some way of illustration with a graphics program, perhaps? (GIMP)

Cheers,
Fridger

[danielj]

What about the halos?

Folks,

Speaking of possible extensions of the galaxy rendering, let me share that I have been thinking of adding a pseudo realistic dust disk to the current F&T disk+bulk rendering of spirals. Perhaps it could give a realistic touch, especially when they are seen sideways. I have been reading the code, but again, with little C++ knowledge and less time, it has been uphill... Perhaps someone else...

Cheers,

Guillermo

Hi Guillermo,

I am not sure whether I understood precisely where you want to place the dust disk in case of spirals. Do you have some way of illustration with a graphics program, perhaps? (GIMP)

Cheers,
Fridger

[BlindedByTheLight]

Hey guys...

Been away for a while. Just saw this post... without going into all 15 pages, has anyone done an OS X version or should I roll up my sleeves?

Steven aka BlindedByTheLight

[t00fri]

Hey guys...

Been away for a while. Just saw this post... without going into all 15 pages, has anyone done an OS X version or should I roll up my sleeves?

Steven aka BlindedByTheLight

Hi Steven,

you might take our FT1 code "to warm up" until our FT1.1 update will be out that contains a number of fixes and further enhancements.

Cheers,
Bye Fridger

[BlindedByTheLight]

Hey guys...

Been away for a while. Just saw this post... without going into all 15 pages, has anyone done an OS X version or should I roll up my sleeves?

Steven aka BlindedByTheLight

Hi Steven,

you might take our FT1 code "to warm up" until our FT1.1 update will be out that contains a number of fixes and further enhancements.

Cheers,
Bye Fridger

Sounds like a good idea to me. As I never really knew what I was doing in the first place - and it's been so long since I've done it - a little warming up is probably in order...