Newtonian Aurora

[Ominous]

We already produce enough food for every body, we just don't distribute it as well as we should.  Also if Africa had the per capita food production of the United States then there would be even more extra food.

Indeed.   World food production generates enough food for every single person on the planet to have 4. 5 pounds of food a day, consisting of all food groups.

[UnLimiTeD]

An then theres the billion or so people that can't eat wheat, or milk, or...
The main problem here is that the food is not evenly distributed, and it's not only a question of incompetence, but also logistics, of possibility.
Transporting food to the areas where people live, from where it's produced, costs time, excessive amounts of energy, and pollution, while increasing the size of the populous will not only result in more produced greenhouse gas, but also additional pollution, as people will want to do something, and production results in a strain to the environment.
The more land is used for habitation, production, or agrarian use, the less will there be for the biosphere; and where actually damn dependent on that.
Note how in large cities the amount of allergies surges upwards?
Those kind of problems will come up, so at some point, we'll have to spend a large amount of the production on health care, and eventually use special infrastructure to recycle gasses and keep our atmosphere healthy.
And the more people there are in one spot, the more damage will be done by natural disasters, which are more likely the more people there are....

[Mel Vixen]

Wellit depends on how much meat a future civilisation would consume. Right now the USA alone could feed 2 Billion people if the meat-production would go down by 90%.

[UnLimiTeD]

Insects.
The food of the future.

[Corik]

I've been reading a lot about newtonian aurora and I think it's cool.  However I'm not sure about space travel.  First of all, if I understand correctly (my english is a little bit rusty) there are 3 types of space travel: some kind of "sub-light" travel, hyperspace and jump drives, right?

I've been doing some quick maths about current sub-light acceleration and it seems a little slow to me.  Maybe it's just that I have got used to Stargate's space travels, I don't know (Daedalus achieves 200. 000 km/s pretty fast).  Another issue I see here is that there is not a speed limit at all.  I really think that there should be one, dependant on ship armor or armor type or a combination of both.  Even if we take structural stability out of the equation, space debris will hit your ships harder and harder at higher speeds, plus there's the light speed limit of 300. 000km/s.  Again, maybe I'm totally biased about speeds because of Stargate, and maybe 200. 000 km/s is way too high speed even at higher tech levels, I don't know.  But I really think "high-end" engines should be able to achieve that for a well armored ship.

About hyperspace, there are lots of theories about it, and I don't really like the idea that your speed in hyperspace is dependant on your speed in real space, or improvements being made by switching to other dimensions.  Again, maybe Stargate biased, but a single hyperspace dimension and improvements being made by more efficient hyperspace engines (from hyperdrives which let you arrive at near stars at a viable speed to high end hyperdrives that let you reach pretty distant stars and even other galaxies if someday it is implemented. . .  who knows!) and those hyperdrives with a fixed speed not dependant on sublight speed.

About Jump Drives I don't have a lot of info right now.  If I understand correctly it works similarly to Battlestar Galactica?

Sorry if my thoughts are offensive in any way, just sharing my thoughts with you guys

[Steve Walmsley (OP)]

I've been reading a lot about newtonian aurora and I think it's cool.  However I'm not sure about space travel.  First of all, if I understand correctly (my english is a little bit rusty) there are 3 types of space travel: some kind of "sub-light" travel, hyperspace and jump drives, right?

I've been doing some quick maths about current sub-light acceleration and it seems a little slow to me.  Maybe it's just that I have got used to Stargate's space travels, I don't know (Daedalus achieves 200. 000 km/s pretty fast).  Another issue I see here is that there is not a speed limit at all.  I really think that there should be one, dependant on ship armor or armor type or a combination of both.  Even if we take structural stability out of the equation, space debris will hit your ships harder and harder at higher speeds, plus there's the light speed limit of 300. 000km/s.  Again, maybe I'm totally biased about speeds because of Stargate, and maybe 200. 000 km/s is way too high speed even at higher tech levels, I don't know.  But I really think "high-end" engines should be able to achieve that for a well armored ship.

About hyperspace, there are lots of theories about it, and I don't really like the idea that your speed in hyperspace is dependant on your speed in real space, or improvements being made by switching to other dimensions.  Again, maybe Stargate biased, but a single hyperspace dimension and improvements being made by more efficient hyperspace engines (from hyperdrives which let you arrive at near stars at a viable speed to high end hyperdrives that let you reach pretty distant stars and even other galaxies if someday it is implemented. . .  who knows!) and those hyperdrives with a fixed speed not dependant on sublight speed.

About Jump Drives I don't have a lot of info right now.  If I understand correctly it works similarly to Battlestar Galactica?

Sorry if my thoughts are offensive in any way, just sharing my thoughts with you guys

Catching a plane in two hours but I thought I had better answer this before Byron (no offence Byron

There are two types of travel for Newtonian Aurora - sub-light and faster than light (FTL). The jump drive is from standard Aurora although I think its probably been used interchangeably with FTL drive in discussions about Newtonian Aurora. In any event the FTL Drive (AKA Jump Drive) is a way to move from normal space into hyperspace and back again in order to exceed light speed.

Stargate is one of my favourite TV programs but its probably not the ideal model for realistic space travel. Space travel works on the principles of Newton's laws of motion

    First law: The velocity of a body remains constant unless the body is acted upon by an external force.
    Second law: The acceleration a of a body is parallel and directly proportional to the net force F and inversely proportional to the mass m, i.e., F = ma.
    Third law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear.

In very simple terms (and ignoring gravity for the moment) to move in a particular direction, you need to throw something in the opposite direction. If you have a 100 ton spaceship and throw a 1 ton object out of the window at 10 meters a second then the ship will move in the opposite direction at 0.1 meters per second. Force = Mass x Acceleration. So the force is equal to a 1 ton mass at 10 meters per second, that same force will move a 100 ton mass at 0.1 meters per seconds.

That is the basic principle behind the rocket engine, except it is the fuel that is being thrown out of the ship at very high speed. For example, if a 1000 ton rocket uses 1 ton of reaction mass per second and that mass leaves the ship at 10,000 m/s (the exhaust velocity), the force is equal to 10,000 m/s x 1 tons, so the 1000 ton rocket will be pushed forward by 10 m/s. Of course, the rocket now only has a mass of 999 tons, so the second ton of reaction mass pushes it by 10.01 m/s and it is now travelling at 20.01 m/s. This will carry on until the fuel runs out (at which point the rocket cannot slow down). The vast majority of the mass of any modern rocket is fuel - the payload is very small in comparison.

As you might guess, the exhaust velocity is very important because the faster the reaction mass leaves the rocket, the more acceleration the rocket will gain from that fuel. However, the energy required to accelerate the reaction mass has to come from somewhere too. In chemical rocket engines, the fuel itself provides the energy from its own combustion. In more exotic engines the energy may come from a nuclear reactor. In any event, achieving high exhaust velocities is the key to fuel efficiency and high speed space flight. This has a limit thought because the exhaust velocity cannot exceed the speed of light (as Yonder recently pointed out .

Newtonian Aurora uses vastly more efficient engines than anything even dreamt of at the moment in real life. The exhaust velocities of the top end engines come very close to the speed of light.

Stargate spacecraft get around these problems by completely ignoring the laws of physics . I did the same for standard Aurora but for Newtonian Aurora I am trying to create a more realistic feel to the game.

Steve

[bean]

Steve: No offense taken.  I probably go too technical some times.  That said, I think you might have missed a few specific points.  Also, I'm not terribly familiar with stargate, so I may be pointing in the wrong direction.
Khalador: There are a number of different models for FTL travel.  For physical realism (or at least lack of impossible) stargates are probably closer then the newtonian aurora system.  That said, we are talking about FTL, so realism is subjective.
Acceleration is limited by a number of factors.  Mostly, the strength of the human body.  We don't work terribly well under even 2Gs, which limits sustained accleration.  The available engines are another limit, as is the ship's structure, but for most cases, the men are the big issue.
A speed limit is unlikely to be a huge problem.  Maybe we could include some armor degradation at certain speeds, but a ship has to be armored against weapons that are more lethal then space debris.  That said, it is something to keep in mind.

[UnLimiTeD]

As for the argument of speed retention in Hyperspace:
Think: How would Hyperspace work?
It's obviously some sort of dimension, in real space, a ship isn't going to suddenly move that fast, and more over, it would definitely keep it's speed when reaching it's target destination.
So, how does that dimension work?
If it's what we assume it to be, the ship will essentially enter a dimension where everything is somewhat smaller, and moving a certain distance will result in a lot higher distance in real space; the efficiency of the engine is basically a matter of how close you apply the magnifying glass.
If the ship would accelerate in hyperspace on it's own, why does it have to decelerate when it jumps out again?
Not desirable, it would require more technobabble (YAY, technobabble!).
A third, potentially working option would be ships moving in Hyperspace like they do in standard Aurora.
This would allow mid-course changes, and not be influenced by starting speed, but it would result in fuel burn over the entire distance. Including range caps.
Steve has decided against this, and I suppose it's fine to have the most newtonian approach available.

[fcharton]

Hi,

This has a limit thought because the exhaust velocity cannot exceed the speed of light

Beware! As soon as speeds get limited to lightspeed, Einstein steps into the picture, and everything becomes quite complicated once objects (any object in theory, but more importantly manned or remote controlled vehicles) achieve relativistic speeds, ie 10-15% of light speed.   

Even in a "purely newtonian" environment, if electromagnetic radiations travel at the speed of light, transmitting information to fast moving objects (ships or missiles) become quite complicated (the signals may take a long while to "catch up").   You could then decide that information can move almost instantaneously through hyperspace, but if so, "hyperspace lasers" could also be built, which would cause problems of their own.

To avoid this, it might be a good idea to create (through the proper use of "dream science") a law which limits all/most practical movement out of hyperspace to non relativisitic speeds.   In other words, there would be a theoretical speed limit at 300 000 km/s, but also a practical one (for ships, fighters, and perhaps missiles) around 40 000 km/s, to keep Newtonian Aurora away from Lorenz transforms. . .   

The problem, I think, is that, if you consider speed is limited to c, the only way to avoid Einstein is to move very slowly.


Francois

[Corik]

Beware! Once you limit speeds to lightspeed, Einstein steps into the picture, and all calculations become much more difficult as soon as objects (any object in theory, but more importantly manned or remote controlled vehicles) achieve relativistic speeds, ie 10-15% of light speed.  

That's why I think sometimes, in gaming and science fiction (Stargate ), physical laws must be bent or simply ignored to make the game or the show more enjoyable.  Are you traveling at relativistic speeds? Invent something that creates some kind of space-time bubble around your ships to maintain coherence.  Are you accelerating at a rate which would kill any human? Put some cool inertial dampener which god knows how it works.  Do you need to turn around your ship to counterattack an enemy ship at your back? Just do it like a boss.

Beside, science change a lot every few years.  Actual working physical laws can be completely wrong in a decade.  Adapting centuries of development and science investigation in our campaings to 21th century physics is like trying to supply water to a growing city through the same pipes.  Sure, they will work for the first 200,000 hundred people, but when the city reaches 1 million inhabitants, those pipes are not going to be enough.

However, I think it's pretty interesting that kind of aproach.  Personally, I would prefer a little "science fiction" here and there, but trying to build a space empire with today's limitations is. . .  challenging at least.

Sorry if I sound like a complete idiot, I'm new here and I don't think I should be arguing about this kind of things.  Beside, I really like your work Steve, you have achieved a level of complexity unseen in any other 4X.  And again, please, excuse me for my poor english skill.

[chrislocke2000]

Hi,

Beware! As soon as speeds get limited to lightspeed.... 

The problem, I think, is that, if you consider speed is limited to c, the only way to avoid Einstein is to move very slowly.

I think you may have gotten a little confused between exhaust velocity and ship velocity. Although the exhaust velocity may get very close to c it's very unlikely that any ship will get anywhere near close to relativistic speeds due to the fuel requirements to achieve this. If you look at the rules thread you will see that Steve has created some example ships to demonstrate the effectiveness of the new engines, in these examples you can see ships will a delta v of not much more than 12,000 kms and that is with a ship with a very large proportion of its mass in fuel.

[fcharton]

I think you may have gotten a little confused between exhaust velocity and ship velocity.     Although the exhaust velocity may get very close to c it's very unlikely that any ship will get anywhere near close to relativistic speeds due to the fuel requirements to achieve this.   

This seems strange to me. . .   
From Tsiolkovsky rocket equation,
deltaV= Vexhaust ln(M_initial/M_final)

For delta-V equal to a fifth of exhaust velocity (to accelerate in straight line to relativistic speeds, with exhaust velocity a bit under c), I need a mass ratio equal to exp(1/5), or 1.  22 (double if I slow down).   The cost in reaction mass is not prohibitive.    That's the gist of the formula : mass ratio only becomes huge when delta v gets higher than exhaust velocity.   

The rest belongs to fuel efficiency: how much fuel I need to accelerate reaction masses to close to light speed.   There's an approximate equation for the energy on the Tsiolkovsky wiki page, in our case, half of reaction mass times velocity times delta-v, or one tenth of reaction mass times exhaust velocity squared, or the energy in one tenth of the reaction mass (going for a 100% efficient antimatter drive).   Again, I see no theoretical limit here.   And besides, it is not relevant to ship speed, just to whether such exhaust speeds are feasible.     

This brings back my original point: if engines with such exhaust speeds are possible, relativistic ships and missiles will probably have to exist in Aurora.   

Francois

[Yonder]

In these examples you can see ships will a delta v of not much more than 12,000 kms and that is with a ship with a very large proportion of its mass in fuel.

That's actually not accurate. While these ships had a large proportion of mass in fuel in comparison to normal Aurora ships (which generally have around half a percentage point of their mass in fuel) they don't actually have a large amount of fuel compared to modern spacecraft. With exhaust velocity at c, then 63% propellant mass will get your spaceship up to the speed of light, and 86% propellant will get it to slow down to a stop again. Those ships may not be good in a fight, but scouts, probes, and missiles could totally reasonably get up to very substantial fractions of c in the late game.

Beside, science change a lot every few years.  Actual working physical laws can be completely wrong in a decade.

That's a misleading way of looking at things. Science changes, but the overthrowing comes in the form of the underlying mechanics, not the observed results. You can't look at something that is demonstrably impossible where current theories work well, and hope some new theory will show that it actually can all happen. It's the poorly fitting edges of the old theories that are cleared up in the next generation of advances.

Beware! As soon as speeds get limited to lightspeed, Einstein steps into the picture, and everything becomes quite complicated once objects (any object in theory, but more importantly manned or remote controlled vehicles) achieve relativistic speeds, ie 10-15% of light speed.   

Even in a "purely newtonian" environment, if electromagnetic radiations travel at the speed of light, transmitting information to fast moving objects (ships or missiles) become quite complicated (the signals may take a long while to "catch up").   You could then decide that information can move almost instantaneously through hyperspace, but if so, "hyperspace lasers" could also be built, which would cause problems of their own.

To avoid this, it might be a good idea to create (through the proper use of "dream science") a law which limits all/most practical movement out of hyperspace to non relativisitic speeds.   In other words, there would be a theoretical speed limit at 300 000 km/s, but also a practical one (for ships, fighters, and perhaps missiles) around 40 000 km/s, to keep Newtonian Aurora away from Lorenz transforms. . .   

The problem, I think, is that, if you consider speed is limited to c, the only way to avoid Einstein is to move very slowly.

That's not necessarily true. The only way to smoothly and totally realistically make faster than light movement impossible would be to actually fully model relativity, however you can do several simpler, yet more hacky and discontinuous affects as well. The easiest thing to do would just have full Newtonian motion until c, and then do an arbitrary ful stop so that nothing could go faster than that. Honestly, that's not any different from doing the same thing at .1c, or .15c. The next step (which may be the best choice) would be to do a little bit of relativity modeling, where you do accelerations and delta-v's using relativity math, and nothing else. For example, if you have a ship going .5c, with a railgun that shoots .6c, a completely Newtonian system would create a projectile going 1.1c, a Newtonian system with a hard speed limit at 1c would make a projectile going 1c, but a relativity system would make a projectile going (totally random numbers here, I'm not looking up the math) .85c.

At that point do we have a realistic system? No, there are a lot of weird reference frame shifts and time distortion affects that wouldn't be modeled, but that's perfectly ok, because that lack of modeling keeps you from getting into trouble.

For example, even though we have instantaneous communications, it's impossible to make hyperspace lasers in the game, because those communications are just completely and totally handwaved. The mechanics aren't actually handled in any way, so contradictions like that can't actually come up.

[fcharton]

Hi Yonder,

The next step (which may be the best choice) would be to do a little bit of relativity modeling, where you do accelerations and delta-v's using relativity math, and nothing else.  For example, if you have a ship going . 5c, with a railgun that shoots . 6c, a completely Newtonian system would create a projectile going 1. 1c, a Newtonian system with a hard speed limit at 1c would make a projectile going 1c, but a relativity system would make a projectile going (totally random numbers here, I'm not looking up the math) . 85c.

I don't think this is "a bit" of relativity modelling.  What you suggest amounts (I think) to calculating everything in Minkowski space and translating it back into one specific frame, the "map frame", the only one the Game understands. 

For projectiles (anything without propulsion), you are using special relativity.  The calculations are a bit more involved than newtonian kinematics, but it is only kinematics.  For ships and missiles, forces and acceleration come into play, and your get a new layer of complexity. 

At this point, you have quite a bit of relativity in the model (not all, since gravity, electromagnetism and causality are not in).

But of course you only need to handle this when "propelled objects" move at relativistic speed.  This is why I suggest to keep this to a minimum. . .

For example, even though we have instantaneous communications, it's impossible to make hyperspace lasers in the game, because those communications are just completely and totally handwaved.

I understand, and it makes perfect sense so long we talk of general in-game information, player omniscience if you like.  I find it less convincing when it comes to tactical information.  Aurora models weapon systems with a lot of details, from power supply and ordnance to detection and fire control.  Not including comunication delays seems a bit strange to me.

Also, I believe that in long distance space battles, the time needed to communicate with missiles is a very important factor, which adds interesting aspects to the game : the further away you fight, the less control you have. . .
But this is another matter.

Francois

[procyon]

The next step (which may be the best choice) would be to do a little bit of relativity modeling, where you do accelerations and delta-v's using relativity math, and nothing else.  For example, if you have a ship going . 5c, with a railgun that shoots . 6c, a completely Newtonian system would create a projectile going 1. 1c, a Newtonian system with a hard speed limit at 1c would make a projectile going 1c, but a relativity system would make a projectile going (totally random numbers here, I'm not looking up the math) . 85c.

Hi Yonder,

I don't think this is "a bit" of relativity modelling.  What you suggest amounts (I think) to calculating everything in Minkowski space and translating it back into one specific frame, the "map frame", the only one the Game understands. 

For projectiles (anything without propulsion), you are using special relativity.  The calculations are a bit more involved than newtonian kinematics, but it is only kinematics.  For ships and missiles, forces and acceleration come into play, and your get a new layer of complexity. 

At this point, you have quite a bit of relativity in the model (not all, since gravity, electromagnetism and causality are not in).

But of course you only need to handle this when "propelled objects" move at relativistic speed.  This is why I suggest to keep this to a minimum. . .

My hope is for realistic game, not reality.  Newtonian is fine for me.  I don't expect Steve to come up with a game capable of modeling all the physics we have available.  If projectiles cross each other at 1+ c, that is fine with me.  The game doesn't need to shift reference for most.  Honestly, most people don't know the math, and I doubt those that do want to spend their free game time worrying about it (I sure don't).  If it was going to be that complicated, we would be harping on Steve to figure in the change in relative size of an object travelling at high velocities just to see if it affects whether we hit the target or not.

If you really want that level of difficulty it takes 9-12yrs at a good institution or two (and a passable doctoral thesis), and then you can deal with these problems regularly - and get paid for it.

I don't expect this level of detail.  Just a good 'realistic feel' with no outright violations (other than FTL travel) of reality.  (I'm sorry if guidance systems on projectiles undergoing 1/4 million G accel felt like a violation for me.)

I understand, and it makes perfect sense so long we talk of general in-game information, player omniscience if you like.  I find it less convincing when it comes to tactical information.  Aurora models weapon systems with a lot of details, from power supply and ordnance to detection and fire control.  Not including comunication delays seems a bit strange to me.

To me the comm issue is less of a hurdle.  I did a fair amount of time in the military and lack of comm is a common problem.  That is what all the training and SOPs are for.  To keep everyone on the same sheet of music without having to check in with each other every few seconds.

Also, I believe that in long distance space battles, the time needed to communicate with missiles is a very important factor, which adds interesting aspects to the game : the further away you fight, the less control you have. . .
But this is another matter.

Francois

Lag time for a non self guided munition would be a problem.  But I really forsee most of the missiles having some onboard guidance systems.  Only time will tell how this game will play out, but I forsee most missile exchanges occuring at very long range with the opponents dropping ordinance and then beginning evasive manuvering to try and run the opposing missile over its delta-v budget so that it will be impossible for it to make intercept.  Groups of ships will likely release missiles from vastly different locations and speeds to bracket a target to make it more difficult for a ship to break away from inbound ordinance.  In this environment, interplanetary range duels will be quite possible.  I forsee the side best able to put missiles on a target from one AU+ to be the winners in this kind of duel.

But as I said, time will see (and I truly can't wait to try it out for myself).