FTL travel/special relativity

[mcwaffles2003]

So we're going to have engines in this game capable of moving significant fractions of the speed of light. I'm not talking about warp drives, but in reality the speed of light is a "speed limit" due to the effects of special relativity at relativistic velocities. KSP doesn't have this speed limiting effect, if you turn on infinite propellant you'll zoom on past light speed in due time. And why would the game prepare itself for that when the highest vacuum ISP engine in stock has an ISP of 4200s.. So, if this game wishes to remain in the original spirit of KSP I think the speed of light would be considered, especially since we will may be seeing craft that if physically built and working as theoretically predicted would travel at significant fractions of the speed of light. They would be held back to these speeds, I believe, due to relativistic effects. So do any of you think some form of special relativity will actually be implemented? Because unless FTL isn't a problem, I think it will have to be.

[HenryBlatbugIII]

Keep in mind that the speed of light is infinite in KSP1.  (One light-second in real life is 30 Mm, but there's no signal delay when you're controlling a probe that's multiple Gm away from Kerbin.)  I doubt they're planning to change that in KSP2.

[Incarnation of Chaos]

3 hours ago, mcwaffles2003 said:

So we're going to have engines in this game capable of moving significant fractions of the speed of light. I'm not talking about warp drives, but in reality the speed of light is a "speed limit" due to the effects of special relativity at relativistic velocities. KSP doesn't have this speed limiting effect, if you turn on infinite propellant you'll zoom on past light speed in due time. And why would the game prepare itself for that when the highest vacuum ISP engine in stock has an ISP of 4200s.. So, if this game wishes to remain in the original spirit of KSP I think the speed of light would be considered, especially since we will may be seeing craft that if physically built and working as theoretically predicted would travel at significant fractions of the speed of light. They would be held back to these speeds, I believe, due to relativistic effects. So do any of you think some form of special relativity will actually be implemented? Because unless FTL isn't a problem, I think it will have to be.

No; because even the more exotic engines are only going to achieve 30-40% of C realistically. And that's assuming they have realistic stats; which they won't because we have a 1/10th scale universe.

So there's no need for Relativistic effects; they're going to balance around the size of the universe which will limit the upper bounds far more than the math could anyway.

[Guest]

53 minutes ago, HenryBlatbugIII said:

Keep in mind that the speed of light is infinite in KSP1.  (One light-second in real life is 30 Mm, but there's no signal delay when you're controlling a probe that's multiple Gm away from Kerbin.)  I doubt they're planning to change that in KSP2.

I wouldn't read too much in the lack of signal delay, that's just a level of abstraction to account for the fact that in real space exploration any probe or ship has a whole team of programmers automating every action.

When you pilot with an actual pilot on board you're impersonating him, when you're piloting a probe you're impersonating the probe's own programming.

I would love the game clarifying this by giving signal delay to science transmission but not to control.

Edited February 17, 2020 by Guest

[KSK]

Complete and utter waste of developer time to implement something that’s only going to be a concern if you turn on infinite fuel.

Also, if a player wants to turn on infinite fuel to get to a destination quickly, why should the developers thwart that by putting a speed limit in anyway? 

[HenryBlatbugIII]

3 hours ago, KSK said:

Complete and utter waste of developer time to implement something that’s only going to be a concern if you turn on infinite fuel.

I don't know.  I'd consider it a fun use of their time to add one specific speed of light effect: a hidden achievement (with a suitably plaid picture of Jeb) that's unlocked when you travel faster than 299,792,458 m/s.

[mcwaffles2003]

7 hours ago, Incarnation of Chaos said:

No; because even the more exotic engines are only going to achieve 30-40% of C realistically. And that's assuming they have realistic stats; which they won't because we have a 1/10th scale universe.

So there's no need for Relativistic effects; they're going to balance around the size of the universe which will limit the upper bounds far more than the math could anyway.

But for those ships that reach 30-40% c they are experiencing increased mass during that climb to those velocities, and if it were not for relativistic effects they would be going a fair bit faster

6 hours ago, KSK said:

Complete and utter waste of developer time to implement something that’s only going to be a concern if you turn on infinite fuel.

Also, if a player wants to turn on infinite fuel to get to a destination quickly, why should the developers thwart that by putting a speed limit in anyway? 

.The mention of infinite fuel was in regards to KSP 1 and chemical rockets, it wasn't referencing future tech.

[Bill Phil]

18 minutes ago, mcwaffles2003 said:

But for those ships that reach 30-40% c they are experiencing increased mass during that climb to those velocities, and if it were not for relativistic effects they would be going a fair bit faster

Eh. 

The difference between 0.4c and 0.43c (calculated using the Newtonion kinetic energy formula after finding KE at 0.4c using relativistic kinetic energy) is small enough that it likely won’t affect gameplay.

Not to mention having to add in a ton of reference frames and Lorentz transformations between ships, planets, and so on.

It really isn’t worth doing.

[KSK]

2 hours ago, mcwaffles2003 said:

But for those ships that reach 30-40% c they are experiencing increased mass during that climb to those velocities, and if it were not for relativistic effects they would be going a fair bit faster

.The mention of infinite fuel was in regards to KSP 1 and chemical rockets, it wasn't referencing future tech.

In that case it’s even more pointless. Without infinite fuel, you’re not going to get to relativistic velocities with a rocket engine, future tech or no future tech. 

My reference point for that statement is Project Daedalus, which was basically a two stage inertial confinement fusion rocket - ie the top end of KSP tech as far as we know. It was projected to reach about 0.12c and it was a one shot deal - forget about slowing down at your destination.

Reaching 0.3 to 0.4c with rocket propulsion is silly. Besides, even at 0.4c your relativistic mass is only about 10% higher than your rest mass.

So including relativistic effects is a lot of faff for a pretty small effect that only becomes a noticeable issue if we’re assuming that KSP2 will let rockets get to implausible speeds anyway.

I’m standing by my original post.

 

[Xd the great]

7 hours ago, KSK said:

In that case it’s even more pointless. Without infinite fuel, you’re not going to get to relativistic velocities with a rocket engine, future tech or no future tech. 

My reference point for that statement is Project Daedalus, which was basically a two stage inertial confinement fusion rocket - ie the top end of KSP tech as far as we know. It was projected to reach about 0.12c and it was a one shot deal - forget about slowing down at your destination.

Reaching 0.3 to 0.4c with rocket propulsion is silly. Besides, even at 0.4c your relativistic mass is only about 10% higher than your rest mass.

So including relativistic effects is a lot of faff for a pretty small effect that only becomes a noticeable issue if we’re assuming that KSP2 will let rockets get to implausible speeds anyway.

I’m standing by my original post.

 

Agreed that relativistic effects are a waste of developer's resource.

However, you underestimated my ability to build fusion rockets with multiple stages.

[Guest]

Simulating time dilation and other relativistic stuff is totally worth it... seeing as everyone will run into them if they want to travel to other stars.

You either travel at a respectable fraction of the speed of light or the alternative is that your journey takes so long that your ship vacuum ablates out from under you and the only thing arriving at the destination is a cloud of dust. Relative time experienced by the ship is a legit consideration effecting the amount of life-support and other resources needed for the trip. Don't be boring.

Edited February 18, 2020 by Guest

[KSK]

1 hour ago, Dale Christopher said:

Simulating time dilation and other relativistic stuff is totally worth it... seeing as everyone will run into them if they want to travel to other stars.

You either travel at a respectable fraction of the speed of light or the alternative is that your journey takes so long that your ship vacuum ablates out from under you and the only thing arriving at the destination is a cloud of dust. Relative time experienced by the ship is a legit consideration effecting the amount of life-support and other resources needed for the trip. Don't be boring.

In no particular order.

Once again - at speeds achievable by rocket propulsion, relativistic effects are small. That Project Daedalus ship I mentioned. Travelling at 0.12c? Its relativistic mass is less than a percent higher than its rest mass. 

Having relative time as a legit consideration assumes that KSP2 is going to include time as a meaningful factor and indeed life support as a meaningful factor. Judging from what we've heard about bases - so far -which seem to be arranged so that the player can set them up and then forget about them, that's at least debatable.

From a gameplay perspective, you've got time dilation backwards. At relativistic speeds, time outside the ship will pass more quickly so that, for example, after a 1 year round trip to Planet X and then back to Kerbin, 10 years will have passed on Kerbin. You'd still need to make sure that your ship was equipped for a 1 year journey - you're not gaining or losing anything there.  I suppose it might make logistics a bit more interesting but again, that assumes that logistics are going to be a factor in KSP2 - see previous comment about bases.

But - lets assume that KSP2 does let you build rockets that can travel fast enough for relativistic effects to be non-trivial. Let's also assume some gameplay mechanics where time is a legit consideration. From a gameplay perspective, how do you communicate relativistic effects to the player so that the player can plan for them or even visualise them in a fairly user friendly manner?

As a (fairly) simple thought experiment, imagine two spaceships. The player sends Jeb off to Planet X at 0.2c and Bob off to Planet Y at 0.4c. The distances to both planets from Kerbin are such that the ships both take a year (measured on their internal clock) to arrive. The player runs a science experiment on each probe and transmits the data back to Kerbin. From Gene's perspective back at Mission Control, neither Jeb nor Bob have even arrived after a year.

More generally, we've now got three frames of reference to think about - Mission Control back on Kerbin, and a separate one for either ship. How do you communicate that to the player? How do you account for the fact that switching between locations on the Map Screen (or the KSP2 equivalent) is also jumping around in time? Which location do you measure that time relative to? 

The whole thing is giving me a headache just thinking about it. It's not boring I suppose but neither is it particularly fun when I just want to get on with the game and have Jeb and Bob transmit their science back to Kerbin so that I can finish researching Ludicrous Speed Drives before the end of the next budget period.

TL:DR. Relativistic effects. Realistic, not boring but no fun and a complete pain to build a user interface around. I vote no.

 

Edited February 18, 2020 by KSK

[mcwaffles2003]

54 minutes ago, KSK said:

In no particular order.

Once again - at speeds achievable by rocket propulsion, relativistic effects are small. That Project Daedalus ship I mentioned. Travelling at 0.12c? Its relativistic mass is less than a percent higher than its rest mass. 

Having relative time as a legit consideration assumes that KSP2 is going to include time as a meaningful factor and indeed life support as a meaningful factor. Judging from what we've heard about bases - so far -which seem to be arranged so that the player can set them up and then forget about them, that's at least debatable.

From a gameplay perspective, you've got time dilation backwards. At relativistic speeds, time outside the ship will pass more quickly so that, for example, after a 1 year round trip to Planet X and then back to Kerbin, 10 years will have passed on Kerbin. You'd still need to make sure that your ship was equipped for a 1 year journey - you're not gaining or losing anything there.  I suppose it might make logistics a bit more interesting but again, that assumes that logistics are going to be a factor in KSP2 - see previous comment about bases.

But - lets assume that KSP2 does let you build rockets that can travel fast enough for relativistic effects to be non-trivial. Let's also assume some gameplay mechanics where time is a legit consideration. From a gameplay perspective, how do you communicate relativistic effects to the player so that the player can plan for them or even visualise them in a fairly user friendly manner?

As a (fairly) simple thought experiment, imagine two spaceships. The player sends Jeb off to Planet X at 0.2c and Bob off to Planet Y at 0.4c. The distances to both planets from Kerbin are such that the ships both take a year (measured on their internal clock) to arrive. The player runs a science experiment on each probe and transmits the data back to Kerbin. From Gene's perspective back at Mission Control, neither Jeb nor Bob have even arrived after a year.

More generally, we've now got three frames of reference to think about - Mission Control back on Kerbin, and a separate one for either ship. How do you communicate that to the player? How do you account for the fact that switching between locations on the Map Screen (or the KSP2 equivalent) is also jumping around in time? Which location do you measure that time relative to? 

The whole thing is giving me a headache just thinking about it. It's not boring I suppose but neither is it particularly fun when I just want to get on with the game and have Jeb and Bob transmit their science back to Kerbin so that I can finish researching Ludicrous Speed Drives before the end of the next budget period.

TL:DR. Relativistic effects. Realistic, not boring but no fun and a complete pain to build a user interface around. I vote no.

 

What if an engine has already been built for it and is open source?

Spoiler

 

Also, as @Xd the great mentioned, I dont think we should underestimate the ingenuity of fellow players getting to and passing the speed of light in a newtonian engine. Also, this game has taught us all orbital mechanics so well, is it a waste of time if we could all also accidentally learn relativity as well?

If it's not in stock though, I really hope this becomes KSP 2's new principia

[Guest]

3 hours ago, KSK said:

TL:DR. Relativistic effects. Realistic, not boring but no fun and a complete pain to build a user interface around. I vote no.

I vote yes. Minus the rest.

2 hours ago, mcwaffles2003 said:

Also, as @Xd the great mentioned, I dont think we should underestimate the ingenuity of fellow players getting to and passing the speed of light in a newtonian engine. Also, this game has taught us all orbital mechanics so well, is it a waste of time if we could all also accidentally learn relativity as well?

My sentiments exactly

[KSK]

3 hours ago, mcwaffles2003 said:

What if an engine has already been built for it and is open source?

  Reveal hidden contents

 

Also, as @Xd the great mentioned, I dont think we should underestimate the ingenuity of fellow players getting to and passing the speed of light in a newtonian engine. Also, this game has taught us all orbital mechanics so well, is it a waste of time if we could all also accidentally learn relativity as well?

If it's not in stock though, I really hope this becomes KSP 2's new principia

Possibly. Assuming that KSP has a sandbox mode I’m sure someone will try. If. Whackjob was still around it sounds like the kind of monster rocket project that he’d take on.

But really, this whole discussion is why I’m not particularly excited about interstellar travel in KSP2.

I know I keep rattling on about this but I tend to use Project Daedalus as a baseline. From Wikipedia:

“Daedalus would be constructed in Earth orbit and have an initial mass of 54,000 tonnesincluding 50,000 tonnes of fuel and 500 tonnes of scientific payload. Daedalus was to be a two-stage spacecraft. The first stage would operate for two years, taking the spacecraft to 7.1% of light speed (0.071 c), and then after it was jettisoned, the second stage would fire for 1.8 years, taking the spacecraft up to about 12% of light speed (0.12 c), before being shut down for a 46-year cruise period.”

Please bear in mind that Daedalus is a one way trip. If you want to go into orbit around anything at the end of the journey you need a Daedalus sized vessel to carry out that breaking burn - and of course you then need an even bigger departure stage to boost your fully fuelled Daedalus up to 0.12c in the first place.

It’s just too big. Multiple hundred thousand tonne vessels, burns that last for literally years and journey times measured in decades. 

In KSP1 I can play in that scaled down sandbox and happily suspend my disbelief because the numbers are still within the right ballpark of the real life numbers. Journeys to the Mun and back in a day, journeys to the nearest planets in months, journeys to the outer planets.

In my opinion, wedging interstellar travel into KSP2 is going to involve fudging the numbers so badly that suspension of disbelief will not be possible and it will become glaringly obvious that we’re playing in a scaled down sandbox. 

The fact that we’re blithely arguing about whether relativistic effects being a noticeable thing is good or not, speaks to that fudging of numbers. Remember - at 12% lightspeed, relativistic effects are still pretty small.

Edited February 18, 2020 by KSK

[Dirkidirk]

8 hours ago, Xd the great said:

However, you underestimated my ability to build fusion rockets with multiple stages.

and you underestimate my ability to build fusion rockets with multiple stages AND multiple boosters, with asparagus staging.

[mcwaffles2003]

8 hours ago, KSK said:

Possibly. Assuming that KSP has a sandbox mode I’m sure someone will try. If. Whackjob was still around it sounds like the kind of monster rocket project that he’d take on.

But really, this whole discussion is why I’m not particularly excited about interstellar travel in KSP2.

I know I keep rattling on about this but I tend to use Project Daedalus as a baseline. From Wikipedia:

“Daedalus would be constructed in Earth orbit and have an initial mass of 54,000 tonnesincluding 50,000 tonnes of fuel and 500 tonnes of scientific payload. Daedalus was to be a two-stage spacecraft. The first stage would operate for two years, taking the spacecraft to 7.1% of light speed (0.071 c), and then after it was jettisoned, the second stage would fire for 1.8 years, taking the spacecraft up to about 12% of light speed (0.12 c), before being shut down for a 46-year cruise period.”

Please bear in mind that Daedalus is a one way trip. If you want to go into orbit around anything at the end of the journey you need a Daedalus sized vessel to carry out that breaking burn - and of course you then need an even bigger departure stage to boost your fully fuelled Daedalus up to 0.12c in the first place.

It’s just too big. Multiple hundred thousand tonne vessels, burns that last for literally years and journey times measured in decades. 

In KSP1 I can play in that scaled down sandbox and happily suspend my disbelief because the numbers are still within the right ballpark of the real life numbers. Journeys to the Mun and back in a day, journeys to the nearest planets in months, journeys to the outer planets.

In my opinion, wedging interstellar travel into KSP2 is going to involve fudging the numbers so badly that suspension of disbelief will not be possible and it will become glaringly obvious that we’re playing in a scaled down sandbox. 

But wouldn't having the game built around these mechanics make modding more smooth on top for that ideal ball park that you are personally looking for? That alone should be more than enough reason to include this. Not to mention the exotic stars and possibly nebulae, black holes, and other galactic wonders. I'd like to see a game that's prepared to take these type of expansions on more fluidly, enabling more modders to continue pushing out the boundary and make the basic mods themselves less taxing overall. Also, if you don't want to leave the solar system out of fear of immersion breaking then just don't leave it, the game isn't going to force you to. The base Kerbolar system will still be there performing more optimally than ever for you.

8 hours ago, KSK said:

The fact that we’re blithely arguing about whether relativistic effects being a noticeable thing is good or not, speaks to that fudging of numbers. Remember - at 12% lightspeed, relativistic effects are still pretty small.

If you believe project Daedalus is the peak for how far this community will go then I believe you are mistaken. Stratzenblitz and Bradley Whistance competing lead to a land vehicle going over 4000 m/s and a race to orbit coming down to 33 seconds.

[KSK]

That’s probably going to be a significant part of my decision whether or not to buy KSP2 actually. Is there a decent game to be had in the Kerbol system or is that just intended to be the starter system and a way to climb the tech tree to the real game aka going interstellar. Hopefully the former.

As for mods - I don’t really care about them to be honest. I’ve got nothing against them either mind, but if a game isn’t fun for me out-of-the-box then I’m not particularly motivated to hunt around for just the right combination of mods to paper over the flaws. I’ve got no shortage of other things to do or games to play.

And no - I don’t believe for a moment that Daedalus is the peak of how far this community will go. However it is my personal ballpark for the numbers involved in somewhat plausible interstellar flight.

Edited February 18, 2020 by KSK

[Xd the great]

Spoiler

Why do we need relativity effects when we can just use FTL Kraken drives?

 

[mcwaffles2003]

2 hours ago, KSK said:

That’s probably going to be a significant part of my decision whether or not to buy KSP2 actually. Is there a decent game to be had in the Kerbol system or is that just intended to be the starter system and a way to climb the tech tree to the real game aka going interstellar. Hopefully the former.

As for mods - I don’t really care about them to be honest. I’ve got nothing against them either mind, but if a game isn’t fun for me out-of-the-box then I’m not particularly motivated to hunt around for just the right combination of mods to paper over the flaws. I’ve got no shortage of other things to do or games to play.

And no - I don’t believe for a moment that Daedalus is the peak of how far this community will go. However it is my personal ballpark for the numbers involved in somewhat plausible interstellar flight.

I also think play within the Kerbolar system will have to be top notch or else it will once again keep new players away and play here will dominate a large portion of any persons play through. I just hope interstellar is the icing and the cherry on top as well as the side of ice cream.

[Guest]

14 hours ago, Dirkidirk said:

and you underestimate my ability to build fusion rockets with multiple stages AND multiple boosters, with asparagus staging.

You both better not be underestimating my ability to build fusion rockets, with multiple stages and asparagus staging AND using the entire solar system as a giant slingshot @_@

Edited February 19, 2020 by Guest

[Dirkidirk]

You both better not be underestimating my ability to build fusion rockets, with multiple stages and BOOSTERS FOR EACH STAGE ALL WITH ASPARAGUS STAGING, using the entire solar system as a giant slingshot, and PUTTING BOOSTERS ON BOOSTERS AND USING A MAGSAIL TO SLOW DOWN! 

[Satellitefanatic]

You all better not be underestimating my ability to build singularity-powered rockets, with multiple stages and BOOSTERS FOR EACH STAGE ALL WITH ASPARAGUS STAGING, using the entire galaxy as a giant slingshot, PUTTING BOOSTERS ON BOOSTERS ON BOOSTERS AND ENCOMPASSING THE SAID BOOSTERS WITH SMALLER BOOSTERS AND ENCOMPASSING THE SMALLER BOOSTERS WITH INVERSE SEPERATRONS, USING A MAGSAIL TO SLOW DOWN, AND UTILIZING THE LANDING LEG KRAKEN WITH DECOUPLERS AS THE FIRST STAGE.

Edited February 20, 2020 by Satellitefanatic

[Bej Kerman]

On 2/18/2020 at 8:57 AM, mcwaffles2003 said:

What if an engine has already been built for it and is open source?

  Reveal hidden contents

 

Also, as @Xd the great mentioned, I dont think we should underestimate the ingenuity of fellow players getting to and passing the speed of light in a newtonian engine. Also, this game has taught us all orbital mechanics so well, is it a waste of time if we could all also accidentally learn relativity as well?

If it's not in stock though, I really hope this becomes KSP 2's new principia

That engine doesn't account for more than one object's time dilation. How would you change what engine a half-built game is using anyways?

[mcwaffles2003]

6 hours ago, Bej Kerman said:

That engine doesn't account for more than one object's time dilation. How would you change what engine a half-built game is using anyways?

Would it be that difficult to just run lorrentz transformations? They're computed in 4x4 matrices just like graphics, maybe link them through GPUs to calculate them faster. I realize this is more difficult than I'm making it but I dont know to what scale the difficulty would be.