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General suggestions for SpaceEngine

Posted: 21 May 2017 11:14
by jasperhb
ephu wrote:
So what is the amount the funding goal has to reach for Vlad to hire another developer?

The exact value is somewhere between Graham's Number and infinity. (It doesn't seem like Vlad's going to hire another developer any time soon.)

General suggestions for SpaceEngine

Posted: 22 May 2017 22:49
by realmezzzz
In the in-game editor, is there a way for automatically calculating length of orbit (like 1-year) based on semimajor-axis and radius of black hole given its mass? Like you could click a button that says 'Calculate' and it sets the expected parameters. Also hide luminosity for non-stars, etc.

General suggestions for SpaceEngine

Posted: 25 May 2017 23:27
by Barnard68
Will Gaia star catalogue be included? 1 BLN stars guys @@ 1 BLN

General suggestions for SpaceEngine

Posted: 25 May 2017 23:32
by realmezzzz
Gaia catalogue has distance data for only 2 million stars which is essential.

General suggestions for SpaceEngine

Posted: 26 May 2017 02:07
by FastFourierTransform
realmezzzz wrote:
Source of the post Gaia catalogue has distance data for only 2 million stars which is essential.

The Gaia catalogue "per se" has not been released with the parallax measurements yet. But the first release, Gaia's DR1, has been integrated with the Hipparcos catalogue (the one that has 2 million stars) to make the parallaxes of Hipparcos more accurate.

In reality the GAIA catalogue would have parallaxes for more than 1.400.000.000 of stars indeed. You just have to wait a few years. Integrating all of that in SE would be trully awesome indeed, I don't think the engine is prepared for this amount of data but Vladimir (A.K.A the creator of the SE universe) said a few times in the old forum that the changes in the core of the engine that he has made will probably allow for this some time soon.

General suggestions for SpaceEngine

Posted: 27 May 2017 14:21
by Mouthwash
It appears that the accretion disks around supermassive black holes rotate much faster than the speed of light. Maybe this is just the result of scaling up from normal sized black holes?

General suggestions for SpaceEngine

Posted: 27 May 2017 14:23
by Mouthwash
I mean, it obviously needs to be fixed - I'm just not sure why they would be this way.

General suggestions for SpaceEngine

Posted: 27 May 2017 14:57
by Mouthwash
I just realized that supermassive black hole size in SE is tied to how large their galaxy is, not their real-life estimated size. This has kind of soured my black hole-gazing experience.

General suggestions for SpaceEngine

Posted: 27 May 2017 18:03
by Watsisname
Mouthwash wrote:
Source of the postIt appears that the accretion disks around supermassive black holes rotate much faster than the speed of light. 

I've looked at a few and it doesn't appear that way to me.  Can you post an example?

General suggestions for SpaceEngine

Posted: 27 May 2017 18:33
by spaceguy
Left picture has been drastically compressed in paint.jpg, but hopefully it's somewhat accurate enough to depict what I mean.
Granules are typically very small compared to the size of the sun, so shouldn't the surface smooth out like left when at such a distance? Sunspots are also typically not uniform across the surface and are varying in shape and size. 

Or is the left picture not accurate at all?

General suggestions for SpaceEngine

Posted: 27 May 2017 19:12
by Hornblower
The left image is pretty accurate. Sunspots form in regions on the sun called "active regions." These storms usually migrate towards the equator of the star. There can be many storms (like 10) on the sun at any given point in time and none at other times. Active regions normally have 2 sunspots, but some can have more. SE is still a WIP. The star surfaces haven't been updated for a while and are by no means realistic. But more realistic star surfaces are definitely planned for the future.

General suggestions for SpaceEngine

Posted: 28 May 2017 01:06
by Mouthwash
Watsisname wrote:
Mouthwash wrote:
Source of the postIt appears that the accretion disks around supermassive black holes rotate much faster than the speed of light. 

I've looked at a few and it doesn't appear that way to me.  Can you post an example?

Looked at both Sagittarius and the central black hole of IC 1101, which I think is the largest one in SE (and whose disk is around a light-year across). i think the speed of the latter is over 20 times c, just by eyeballing.

General suggestions for SpaceEngine

Posted: 28 May 2017 01:39
by PlutonianEmpire
Mouthwash wrote:
Watsisname wrote:
Mouthwash wrote:
Source of the postIt appears that the accretion disks around supermassive black holes rotate much faster than the speed of light. 

I've looked at a few and it doesn't appear that way to me.  Can you post an example?

Looked at both Sagittarius and the central black hole of IC 1101, which I think is the largest one in SE (and whose disk is around a light-year across). i think the speed of the latter is over 20 times c, just by eyeballing.

The way I tried to find out for myself was to put the camera in airplane mode, and then try to match the speed you see on the animated details of the AD, while simultaneously trying to maintain a constant speed and distance from the BH as close to it as possible. Then check your speed readings to see if c > 1. My computer wasnt the most ideal for this maneuver, so maybe someone with a faster computer and a better observant eye can try. :)

General suggestions for SpaceEngine

Posted: 28 May 2017 02:05
by Mouthwash
PlutonianEmpire wrote:
Mouthwash wrote:
Watsisname wrote:
I've looked at a few and it doesn't appear that way to me.  Can you post an example?

Looked at both Sagittarius and the central black hole of IC 1101, which I think is the largest one in SE (and whose disk is around a light-year across). i think the speed of the latter is over 20 times c, just by eyeballing.

The way I tried to find out for myself was to put the camera in airplane mode, and then try to match the speed you see on the animated details of the AD, while simultaneously trying to maintain a constant speed and distance from the BH as close to it as possible. Then check your speed readings to see if c > 1. My computer wasnt the most ideal for this maneuver, so maybe someone with a faster computer and a better observant eye can try. :)

Just speed up time and watch from a distance, no?

General suggestions for SpaceEngine

Posted: 28 May 2017 03:04
by Watsisname
Mouthwash wrote:
Source of the post Looked at both Sagittarius and the central black hole of IC 1101, which I think is the largest one in SE (and whose disk is around a light-year across). i think the speed of the latter is over 20 times c, just by eyeballing.

Ok, I checked and calculated directly rather than eyeballing, and you're right, it is a few times faster than c for the middle and outer parts of the disk.

The problem is that the current implementation of accretion disks is limited to rigid rotation (and a shrinking), so all parts of it rotate with the same angular velocity.  The rotation rate itself is actually calculated correctly, but for the inner part of the disk very close to the hole (if you apply it there for SgrA*, for instance, it is less than c and about the correct velocity from Kepler's Laws).  So naturally the outer parts having the same angular velocity have faster linear speeds, and can exceed the speed of light.  

The only way to fix this to be more realistic is to change way disks are rendered in such a way that allows them to be sheared.