Jump to content

Einstein and KSP 2


SOXBLOX
 Share

Recommended Posts

If we're getting near-rockets in KSP 2, the devs will have to implement relativistic equations and time dilation, right? KSP 1 is Newtonian, in that it seems to permit arbitrarily high speeds, though for chemfuel rockets this works fine. Has this been discussed before, and are there any answers on it? 

Link to comment
Share on other sites

2 minutes ago, MechBFP said:
32 minutes ago, SOXBLOX said:

the devs will have to implement relativistic equations and time dilation, right?

Nope. Why would they have to?

It wouldn't be too useful, but would still be a fun feature to see as a patch or a mod.

Link to comment
Share on other sites

I haven't seen anything in the information for KSP2 that suggests 'near-c' travel; Daedalus drives and other fusion tech with delta-V in the hundreds of thousands or even the millions, yes, but that still only grazes 1% of light speed, or 10% if light is scaled to the same scale as the Kerbal universe (~1/10 of real size). I don't see the value in trying to add this sort of thing as it would only complicate things for no obvious gain except 'realism' and would detract from the game's playability by adding another layer of stuff to wade through in order to lob some Kerbals at another star.

Link to comment
Share on other sites

6 hours ago, SOXBLOX said:

If we're getting near-rockets in KSP 2, the devs will have to implement relativistic equations and time dilation, right? KSP 1 is Newtonian, in that it seems to permit arbitrarily high speeds, though for chemfuel rockets this works fine. Has this been discussed before, and are there any answers on it? 

Time has to flow at the same rate for all the players. That limits what you can do with relativity. For example, if we time-warp players to matching global time, time on ships at near-light speeds may be running at slow enough rate to be effectively unplayable.

There are ways to mess around with all of this, but I think I"d personally prefer Galilean relativity with purely Eucledian space-time. In other words, no relativistic effects and time being globally shared.

Link to comment
Share on other sites

14 hours ago, jimmymcgoochie said:

Daedalus drives and other fusion tech with delta-V in the hundreds of thousands or even the millions, yes, but that still only grazes 1% of light speed, or 10% if light is scaled to the same scale as the Kerbal universe (~1/10 of real size).

I think that fusion drives could start getting you closer to 5% c, particularly staged fusion drives (but with 10% c dV, unless you are just doing fly-bys, you only head to the other star at 5% c). The end game "torch ship" drive, that has been speculated to use antimatter (pure matter-antimatter? or antimatter activated fusion, who knows?), would likely have fractions much higher.

Even with these higher numbers, I think its not a problem (except maybe the torch ship) - I wouldn't scale C down to 1/10th our light speed - and the 1/10th scale means that even higher fractions of c aren't needed for interstellar travel, so you can stay at low c%s, and still get to other stars in reasonable time frames.

http://www.projectrho.com/public_html/rocket/slowerlight3.php#gamma

Note that you can get to 40% the speed of light before the time dialation factor (and lenght ocntraction, nad other weirdness) is 10%... which is enough for me to ignore, and enough that I wouldn't criticize KSP 2 for ignoring it.

The atomic rockets guy sets his threshold at a gamma of 1.01 (not 1.10), which corresponds to 14% c http://www.projectrho.com/public_html/rocket/slowerlight.php

Which is still faster than we are likely to see in KSP 2 with fusion engines (really not sure about the "torchship engine"), so I don't think its a problem (and yet I think other engines are a problem, so hopefully this also shows I'm not just complaining about any "future tech").

Link to comment
Share on other sites

15 minutes ago, K^2 said:

I'm not following that logic.

I suppose it’s related to the inherent difference in time that MP would cause for KSP - that is there would have to be a way to account for different time warp settings in a server so that the game works.

Introducing Special Relativity wouldn’t be hard mathematically - rather it might be problematic because you have to accomodate it. A way to switch reference frames in map view might be desirable. But then you might as well add n-body physics since that’s also pretty easy mathematically and having the ability to switch between different reference frames in map view would also benefit that. 

There may also be a sizable performance hit as various transformations would be needed at all times and some calculations can be relatively intensive.

It may also overly complicate multiplayer.

I can’t see it being worth it. It likely won’t add much challenge and it doesn’t seem to improve the experience. But that’s just me.

Link to comment
Share on other sites

2 hours ago, Bill Phil said:

I suppose it’s related to the inherent difference in time that MP would cause for KSP - that is there would have to be a way to account for different time warp settings in a server so that the game works.

Yeah, but allowing players to run at different warp is unsolvable. Never mind the re-simulation, you just can't get causality right. If I time-warp to tomorrow and dock with the station, doing the math to simulate it forward a day is pretty straight forward. But if another player who hasn't time-warped then goes to the station, collides with it, and destroys it, they've still done "yesterday" from my game's perspective. So now my game learns that the station has been destroyed after I've already docked to it. Oops.

So we simply can't run simulation at different rates for different players. However Intercpet decides to solve time warp, there is still going to be a shared rate at which time flows for every player by strict necessity. If somebody time-warps, everyone time-warps. And that just isn't how relativity works. If I got to near light-speed, a minute of my time might correspond to ten minutes of time for another player. The only way to keep up with it is for my simulation to go to warp 0.1. And that's just going to suck. This is why I'm not following logic in @Gargamel's post. Relativity being easy doesn't follow from MP being there. Just the opposite. Doing relativistic sim in a pure single player - that would be peanuts.

2 hours ago, Bill Phil said:

But then you might as well add n-body physics since that’s also pretty easy mathematically and having the ability to switch between different reference frames in map view would also benefit that.

I'm actually not sure you can do n-body physics without introducing contradictions for players in different frames of reference unless you go full GR. Now that would be expensive to do computations on. With SoI orbits, I think you can still handle this, so long as you account for ladder paradox.

2 hours ago, Bill Phil said:

There may also be a sizable performance hit as various transformations would be needed at all times and some calculations can be relatively intensive.

This probably isn't a place to for me to geek out and get too technical on similarities between Lorentz boosts and coordinate transformations*, but bottom line, both the relativistic frame changes in 3D + time and non-relativistic 3D transformations that include rotation and translation are handled with 4D matrix multiplication. Because games have to handle a lot of rotations and translations, the hardware and math libraries for video games are built to handle these in very efficient way, and so incidentally built to be very efficient at making huge number of relativistic computations as well. So this actually isn't a problem at all.

* Broadly, the relationship between the two is via Geometric Algebra.

Link to comment
Share on other sites

2 hours ago, K^2 said:
5 hours ago, Bill Phil said:

I suppose it’s related to the inherent difference in time that MP would cause for KSP - that is there would have to be a way to account for different time warp settings in a server so that the game works.

Yeah, but allowing players to run at different warp is unsolvable. Never mind the re-simulation, you just can't get causality right. If I time-warp to tomorrow and dock with the station, doing the math to simulate it forward a day is pretty straight forward. But if another player who hasn't time-warped then goes to the station, collides with it, and destroys it, they've still done "yesterday" from my game's perspective. So now my game learns that the station has been destroyed after I've already docked to it. Oops.

Ask the developer of Dark Multiplayer how to deal with this. I don't know how DMP solves paradoxes (reverts to docked player's instance of the station when attacker unloads station and syncs with docked player?), but it's good enough for KSP.

Link to comment
Share on other sites

4 hours ago, Bej Kerman said:

Ask the developer of Dark Multiplayer how to deal with this. I don't know how DMP solves paradoxes (reverts to docked player's instance of the station when attacker unloads station and syncs with docked player?), but it's good enough for KSP.

It effectively doesn't. It just syncs game states. So every player runs the sim for their own ship at their own rate, and the current position of the ship is reported. So to another player, it just looks like your ship instantly accelerated to ludicrous speed whenever you warp. There's also, apparently, an option to run the game with the same warp setting applied to everyone. I'm not really sure if just one player controls it, or if anyone can change the warp for everyone.

Neither of these are compatible with relativity in any meaningful way.

Link to comment
Share on other sites

14 hours ago, K^2 said:

I'm not following that logic.

 

9 hours ago, Kerbart said:

I am. I’m pretty certain @Gargamel meant “if they can figure out multiplayer, the complexities of special relativity are trivial

Yes, it was a tongue in cheek sarcastic comment about how hard MP is to work out. 

Link to comment
Share on other sites

32 minutes ago, Gargamel said:

Yes, it was a tongue in cheek sarcastic comment about how hard MP is to work out. 

See, that's why it confused me. Because in single-player game, relativity really is simple. It's when you have to have several observers (players) sharing the timeline that things get very complicated. Hence, while I agree that making multiplayer in general is way harder than making a single-player game with relativity work, making a game with multiplayer and relativity is almost impossible without making something either irrelevant or not fun. Because multiplayer is the thing that makes including relativity in KSP2 hard, cursed, even, that seemed like a total non-sequitur of a statement.

Link to comment
Share on other sites

If nearby star systems are 0.4 to 1 light year away (1/10th scale, so like proxima centauri - Epsilon Eridiani in real life), and you can get to 10%c, then it takes 10 Earth-years of game time to get to nearby stars. This is about 10x as long as it takes to get to Eeloo by hohman transfer, but still quite reasonable. Time dialation at these speeds would be insignificant.

Its only 1% difference at 14% c, and still less than 10% at 40%c.   As long as they don't make these engines powerful enough to go beyond about 0.5c, the time dialation effect can be ignored. 

I think we don't need to worry.

Also, if we did have separate time warp rates, your time to reach the nearest system would be the same. You see, if you were going at near light speed to a star 10 light years away, it wouldn't take 10 years of ship time, it would be nearly instant in terms of ship time, because lenght contraction would make it seem like the ship wasn't 10 light years from the star.

So if its a 10 light year journey, and there's one time flow rate for players, the playing time to reach that other star will be the same with and without relativity, even at 0.99c.

Sure at 0.99c your time warp rate will have to be much lower than the time warp rate for a player doing an inter system-hohman transfer to Eeloo, to stay in sync... but your ship will not be making a 10 light year journey from its perspective, but a journey much much shorter.

So we're just limited by syncing times for players, which yields the same problem as if relativity is ignored, and you want to go interstellar, while someone else wants to go to Mun from Kerbin.

At least... that's my understanding of it...

Link to comment
Share on other sites

On 7/21/2020 at 4:49 AM, έķ νίĻĻάίή said:

I seriously doubt that we're even going to approach anything near lightspeed

You can get past light speed in KSP if you use an high twr engine, probe core, an reaction wheel and a rtg
I guess some monster asparagus ship with high end engines, lots of fuel and let i run for an year. 

Still you can not have time dilation in an game with no communication delay and you can jump between ships. The clock will be a bit off in the fast ones and few would notice. 
Now you could lower acceleration if getting close to light speed, again few outside of people exploiting will notice. 

Launched an probe a bit after posting this with 24 sepratrons without fuel and infinite propellant cheat, its doing 60 g, just passed Duna orbit and reached 1% of c, game say 2 hour ago but run on 4x physical speed. 
Two hour to Dress orbit, going to bed now :) 
 

Edited by magnemoe
Link to comment
Share on other sites

On 7/20/2020 at 9:49 PM, έķ νίĻĻάίή said:

I seriously doubt that we're even going to approach anything near lightspeed

You forget that we are going to strap 100 giant nuclear-pulse engines together with struts and duct tape and slingshot around the biggest star in the game with the monstrosity.

Link to comment
Share on other sites

2 minutes ago, cubinator said:

You forget that we are going to strap 100 giant nuclear-pulse engines together with struts and duct tape and slingshot around the biggest star in the game with the monstrosity.

Bruh, that is single-handedly the best idea since sliced bread!! :D

Link to comment
Share on other sites

This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...