relativistic effects in orbiter

[Topper]

Hi,

i have some time in my chrismas holydays and some ideas how to simulate relativistic effects in orbiter!

At first, we can use the "time accelerator" to simulate the "time dilatation".
For example, if youre focus is on a ship, the time accelation will be set automaticly in relation to the "Earth time" and accordingly the relativ speed to earth. (I will use earth as reference because the clock in orbiter is showing the time on earth :lol
The formulaic is:

t' ... Ship clock time
t ... Earth clock time
v ... speed (in c? 0.9 means 90% light speed i think) relativ to earth
c ... the speed of light (299 792 458 m/s)

I have to think about how to calculate the acceleration factor from this formulaic
to that a clock in an MFD will show earth-time and ship-time.

What do you think about this idea will it be possible?
I will try to make a "Einstein MFG" to test it out!
Have you more ideas like this witch you want to see in my Einstein MFD?

Topper


edit
oh that is easy: The time acceleration (a) must be:
a = sqrt(1-(v*v/c*c))
or
a = sqrt(1-(c*c/v*v))
hmm i will try it iam not einstein...
lol

 

[Thunder Chicken]

There was another thread that discussed this idea.

The fundamental problem comes in when you attempt to have multiple views or players - as time is relative to the observer, how do you communicate the fact that different viewers perceive themselves and each other at different times?

 

[RisingFury]

I think the better question is: Do you really *need* relativistic physics in Orbiter? I mean, if you look at it, the fastest I've ever gone is around 200 km/s, relative to the Sun and that's still not even 0.1% of the speed of light. If you look at the function the equation describes, you'll notice that there is not much of a difference until you come to like 15% of speed of light... until then, it's pretty much no difference.

Also, the v in your equation is the relative velocity, not the percentage of speed of light.

If you take 200 km/s and put it in your equation, you'll notice your time is still going at 99.96% of what it usually would. And given that most of the time velocities are way lower (~11 km/s will get you to the Moon, a bit more to Mars,...), I really don't think there is any need for relativistic effects in Orbiter.

 

[Topper]

I think the better question is: Do you really *need* relativistic physics in Orbiter? I mean, if you look at it, the fastest I've ever gone is around 200 km/s, relative to the Sun and that's still not even 0.1% of the speed of light. If you look at the function the equation describes, you'll notice that there is not much of a difference until you come to like 15% of speed of light... until then, it's pretty much no difference.

Also, the v in your equation is the relative velocity, not the percentage of speed of light.

Yes ok u are right, but you can set c=1 , then c will be the percentage vale of youre c . (Sorry stupid answer i know it :lol

If you take 200 km/s and put it in your equation, you'll notice your time is still going at 99.96% of what it usually would. And given that most of the time velocities are way lower (~11 km/s will get you to the Moon, a bit more to Mars,...), I really don't think there is any need for relativistic effects in Orbiter.

Hmm it's depend on witch ship u wan't to fly.
And it will be funny i think

 

[Andy44]

Back on M6 Martins ran a thread in which he discussed the possibility of building a second sim which would simulate the effects of relativity. Since he built Orbiter as a tool for demonstrating Newtonian physics, he said he was thinking of building another for the purpose of exploring relativity. He also said it would be, at best, a back burner project so don't hold your breath. Besides, one outstanding, mind-blowing sim is enough for me for now.

 

[jedidia]

Another problem prone to show up is that our current navigational tools will get in trouble when you simulate relativistic physics. On the other hand, when moving at speeds that high, our Nav-tools aren't that useful anyways.

 

[TJohns]

Check out Virtual Relativity to see how the world looks at high speeds...
http://www.vis.uni-stuttgart.de/relativity/vr/

 

[cr1]

the fastest I've ever gone is around 200 km/s

I remember having been to something like 0.47AU/s after bouncing off the Sun with the default DeltaGlider... (I originally wanted to try landing on it)

 

[Imagineer]

I think the better question is: Do you really *need* relativistic physics in Orbiter? I mean, if you look at it, the fastest I've ever gone is around 200 km/s, relative to the Sun and that's still not even 0.1% of the speed of light. If you look at the function the equation describes, you'll notice that there is not much of a difference until you come to like 15% of speed of light... until then, it's pretty much no difference.

While the realistic speeds of space vehicles limit relativistic effects to the fifth significant digit or less, sometimes even these small errors can render a system useless if not corrected for. One example is the Global Positioning System. http://en.wikipedia.org/wiki/Global_Positioning_System#Relativity

 

[Topper]

Hi!
Iam working on a MFD witch can show an "relativistic clock" (the dt between 2 moving objects where ever they are).

For example, if one object is on earth and one object is moving "near the speed of light", it can show you 2 different dates. The date on Earth and the date inside the ship.

The time-dialation related to the speed is no problem and this is allready working (the calculation is easy with the formula i've posted) .
But now i have to think aboute the time-dialation in relation to the gravity.
For example, if one "Clock" is on earth and one is orbiting the earth it is easy too, using the formula:

Dt2 = sqrt(1-((2GM)/(c*c*r)))*Dt1

Dt1 => delta t in system1
Dt2 => delta t in system2
c => Speed of light
r => Radius to reference body
G => Gravitational constant
(Sorry for writing in these c-like syntax!)

But what happend if one object is on earth (grounded at 2000m alt, for example) and one object is in jupiters orbit? Then i have 2 different masses and 2 different radii.
The next quetion is what is happening when one "System" is in the middle of two gravity objects? For example, one ship is near the Lagrange point or between earth and moon? How i can calculate things like this?

I do not really know what really would happen in these cases.
I think i can use the Force Vectors acting to these 2 objects right?
( For Coders:
vessel->GetForceVector(&V3);
double VTotal = sqrt((V3.x*V3.x)*(V3.y*V3.y)*(V3.z*V3.z));
... or something like this ... and something more...
)​

Can someone tell me a formula (witch is using forces) for these problems?
I know, this is a hard quetion but thanks for helping!

 

[RisingFury]

While the realistic speeds of space vehicles limit relativistic effects to the fifth significant digit or less, sometimes even these small errors can render a system useless if not corrected for. One example is the Global Positioning System. http://en.wikipedia.org/wiki/Global_Positioning_System#Relativity

Yes. GPS requires very accurate time keeping. 4 satellites are needed to send out exact time so you can calculate your position. Since the difference in time received from the 4 satellites are small enough, relativistic effects do make a big difference over time.


It's true that Orbiter would be more accurate with relativistic effects, but the first thing that should be done to increase it's accuracy are hidden in the computer itself. Computer can only hold a finite amount of decimals, which means you don't have infinite accuracy in your numbers. I think that error alone is larger then relativistic error in most cases.

 

[garyw]

Only three GPS satellites are needed to work out postition. With four you get altitude as well.

Obviously the more the better but for postition just the three.

 

[Imagineer]

Only three GPS satellites are needed to work out postition. With four you get altitude as well.

Obviously the more the better but for postition just the three.

With GPS navigation you have four unknowns: Your position in three dimensions and the exact time. Thus you need four measurements to solve for the four unknowns.

If you know your altitude then three satellites are "enough" because the altitude "measurement" replaces one satellite measurement.

But suppose that two satellites you are using are each near a point where their orbits cross? In that case a "small" measurement error could cause a "large" displacement in your horizontal position. This is called "Geometric Dilution of Precision".

And suppose the temperature control on one of the atomic clocks on a satellite fails, which has happened once before? You would get a bogus position but how would you know?

For these reasons few modern GPS receivers are content to track just three or four satellites. Even some consumer grade hand-held models will track up to 12. This allows averaging to reduce the probable error as well as allowing a failing satellite to be identified and kicked out of the navigation solution. This latter feature is called "Receiver Autonomous Integrity Monitoring".

I spent five years at a major aircraft manufacturer integrating GPS with the rest of the navigation and display systems. During that time I got to learn more than anybody wants to know about leap seconds, the speed of propagation of microwaves through the ionosphere, and the undulation of the geoid.

GPS is a huge topic with a lot of math and physics behind it. It is an interesting topic to explore if you are so inclined.