# Realistic Distances in Space Games

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So I was playing around with my space shooter today and I decided to turn the governor off and throttled my space ship up to 50,000 pixels per second. My games scale is 1 pixel = 1 foot The Speed of light is 983571057.9254742 p/s My ship is traveling at 2.5417% the speed of light, It would take my ship 40 years to travel 1 light year Alpha Centauri is 4.36 Light years away from earth. At 50,000 p/s it would take my ship 174.4 Years to travel that distance That might help to give people an idea how fast the speed of light is. Any thoughts?

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You can't see the ship.

BTW my library could find closest position of two ships with error under 100 meters even when they both started at opposite sides of the galaxy. 100000 light years.

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well you can see the ship if your camera is bound to it.

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The way I see it, you have only a few choices: Make the universe unrealistic, situate stars closer together, use FTL technology, create some mechanism by which players are immortal or long lived (but why?), or hide the numbers so that such calculations are impossible.

What is the essential feeling you're going for? Ultra-realism? If so, you could dip into extreme physics (mirror matter? virtual particles?) and explain realistic distances away that way.

Personally, I'm a fan of jump technology. I don't want to sit through even 10 minutes of spaceflight if there's nothing to do.

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Hypergates! Create artificial wormholes which link two points in space such that your ship can transverse seemingly long distances instantaneously!!

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The other thing you could do would be to make the entire plot take place inside a single slar system. Why do you have a finite speed? Couldn't you just keep accelerating indefinietly? it's certaintly not realistic to have a particular speed. The best way to do spaceflight if you hae sustainable thrust is to thrust untill you get halfway to where your going, then turn around and decellarate. the apollo missions didn't do that because they didn't have sustainable thrust, Hydrogen rockets can only give bursts of thrust.

In my game, there will be ten minute transit periods, but there will be always something to do, always some way to indirectly attack your enemy.

I think that you will find that your scale will be too small, given the vastness of space. What scale were you thinking of for engagement sizes? how far apart will ships be when fighting?

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Quote:
 Original post by NIm[...]Why do you have a finite speed? Couldn't you just keep accelerating indefinietly? it's certaintly not realistic to have a particular speed.[...]
Einstein disagrees with you. Modern physics claims it would take infinite energy to reach light speed, so you can't go any faster than that. The faster you go, the more energy it takes to accelerate according to theories einstein worked out that have been shown at least somewhat accurate (more accurate than newtonian physics for sure).

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Of course. I apologize for not taking this into consideration. But surely, that is a minor factor at .02c! Furthermore, as you accelerate, youy subjective time changes, so that less time apears to pass than actually does. One interesting effect of this is that as you accelerate, your total travel time as percieved by you decreases, although I am not sure whethter the effect of time dilation exactly cancels the effect of increasing mass. Your speed with respect to an observer, however, approaces c, but never achieves it.

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I like the way Freelancer does it.

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Some sort of 'jump' technology is the best solution to this problem, in my opinion. I'm slightly biased, though, since it's the solution I'm using. Depending on the ship type, travel in-system is done either via regular sub-light travel or instantaneous jump drives. The design calls for the primary player controlled ship types to all be jump-capable, but other ships in the game universe will be limited to sub-light speeds (mostly commercial vehicles). Some sort of gate technology will allow travel between systems so that I don't even have to consider that particular problem.

One advantage to this approach is that you can realistically limit sub-light speeds. Fuel (or reaction mass for the ship's power source) is heavy and probably expensive to get into orbit. If ships are meant to operate for extremely long periods of time in space, they're probably not going to be burning fuel constantly. Even in a game with psuedo-realistic physics, this effectively limits top speed. You could implement this into the game with some sort of safety that prevents the player from continuously burning for too long or you could actually model fuel/reaction mass consumption over time.

Personally, I'm using a very abstract model for ship reaction mass, but I'm also severely limiting the speed of ships. Since my game design calls for ships to remain in space for very long periods of time, I figured they'd be powered by some sort of fission or fusion reactor. It'd be impractical to rely on chemical rockets for extended space travel, so instead ships use a kind of ion thrusters. Ion thrusters generally provide fairly low thrust, so having the player accelerating constantly to cover long distances with sub-light engines would be impractical. The engines will probably be slow enough that constant burn over a period of weeks or months would be required just to travel between two nearby planets. Even with time acceleration it wouldn't make much sense for the player to take that route.

Another nice advantage to using an instant 'jump' system instead of just a really fast, linear FTL system is that you're not required to model the VAST distances you'd normally encounter in space. You only have to carefully track the position of objects within the player's jump range. Everything beyond that can be modelled in significantly less detail, relative to the player's jump 'sector'. It only becomes important to know exactly where the objects are when the player gets close.

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The way Freelancer handles space travel is fairly decent. It's very similar to the system in Cowboy Bebop. In Freelancer, they have trade laners which are basically a highway system between planets in the solar system. These gates accelerate the ships to much faster speeds (I don't think its quite FTL speeds). The ships themselves are basically pulled/shot to the next system through a series of gate, kind of like a rail gun. For system to sytem, they have to rely on massive jump gates.

I think the jump gate idea is fine. The trade lane idea bothers me a little since I don't think it really takes into account the fact that all of the planets rotate around the sun at different distances and different speeds. So there would be times that I think planets would become unreachable without making major detours.

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The way I'm handling this sort of problem is by starting the player on the surface of ganymede, in the Jupiter system, and thnologically stipulating a speed of about 0.03c to be average, so yu get around very quickly. as time goes on, I'll have ships that travel at ridiculous speed like .7c towards the endgame. I will not have faster than light travel, but in the single player campaign mode, I will have time comression, in addition to the time dilation as described by einstein. I won't have either in the multiplayer game, but in multiplayer, the tech-level, and therefor the speeds that it is possible to achiev quickly, will determine how far apart opposing ships start. at low tech, combat will be accross very short distances(both ships in the same orbit around a planet, on opposite sides of it) and at high tech levels, accross very large distances(one ship starts in low earth orbit, and another ship shows up in jupiter orbit. They close the distance very quickly, because I ignore einsteinian effects in multiplayer.)

if you use time dilation, you can do all sorts of interesting things

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I was thinking about single scenario oriented game where a player needs to defeat an alien invasion force in our solar system in the near future. The player would be responsible for constructing and positioning defensive forces. The player would also be responsible for plotting the combat missions and trajectories from earth to wherever taking into account travel time, gravity and so on.

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Quote:
Original post by Extrarius
Quote:
 Original post by NIm[...]Why do you have a finite speed? Couldn't you just keep accelerating indefinietly? it's certaintly not realistic to have a particular speed.[...]
Einstein disagrees with you. Modern physics claims it would take infinite energy to reach light speed, so you can't go any faster than that. The faster you go, the more energy it takes to accelerate according to theories einstein worked out that have been shown at least somewhat accurate (more accurate than newtonian physics for sure).

Actually Einstiens theories disallow the movement of particles that have mass at the speed of light. Moving faster than it is allowed hence tachyon particles. Tachyon particles are particles which move faster than the speed of light, and when they lose energy they actually go faster. Therefore, it takes energy to approach the speed of light from either end and it takes infinite energy to travel at it unless you don't have any mass (like a photon of light). Of course it is impossible (unless some other theory comes around) to accelerate from below the speed of light to above it without ever traveling at that speed. That keeps "slow" particles from ever exceeding the speed of light.

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Quote:
Original post by T1Oracle
Quote:
Original post by Extrarius
Quote:
 Original post by NIm[...]Why do you have a finite speed? Couldn't you just keep accelerating indefinietly? it's certaintly not realistic to have a particular speed.[...]
Einstein disagrees with you. Modern physics claims it would take infinite energy to reach light speed, so you can't go any faster than that. The faster you go, the more energy it takes to accelerate according to theories einstein worked out that have been shown at least somewhat accurate (more accurate than newtonian physics for sure).

Actually Einstiens theories disallow the movement of particles that have mass at the speed of light. Moving faster than it is allowed hence tachyon particles. Tachyon particles are particles which move faster than the speed of light, and when they lose energy they actually go faster. Therefore, it takes energy to approach the speed of light from either end and it takes infinite energy to travel at it unless you don't have any mass (like a photon of light). Of course it is impossible (unless some other theory comes around) to accelerate from below the speed of light to above it without ever traveling at that speed. That keeps "slow" particles from ever exceeding the speed of light.

Light does have mass. This is why light is affected by gravitational fields and why it's possible to use large gravitational concetrations as lenses to peering at extremely long distances and why even light can't escape a black hole. What light doesn't have is any _rest_ mass.

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I thought it was because gravity bends space time? Or am using an out of date model of the universe? Hmm, you may be right.

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Does light have mass?

Incidentally, tachyons are completely speculative. There is no evidence that they actually exist, in fact most scientists think they probably don't. They were merely proposed as an interesting theoretical "what if?". One derived property of tachyons is that their mass would be an imaginary number.

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Quote:
 Original post by SandmanDoes light have mass?

The answer seems to be that the equations "work", but that intelligent people who know what they're talking about disagree (or remain agnostic) about what the equations "mean" metaphysically/philosophically. (cf. "observations" in quantum mechanics) For example, does E_0=mc^2 mean that energy and mass are two names for the same thing (Is it a sub, a hoagie, a po'boy, or a hero?), or does it mean that they are distinct but one can convert between them (Ice Water Vapor)?

Quote:
 Incidentally, tachyons are completely speculative. There is no evidence that they actually exist, in fact most scientists think they probably don't. They were merely proposed as an interesting theoretical "what if?". One derived property of tachyons is that their mass would be an imaginary number.

We usually throw out the imaginary part of solutions (in particular when dealing with waves), so perhaps we should throw out the imaginary part of the tachyon solution? Or, maybe there is a physical significance to the imaginary part of waves (as opposed to simply being a mathematical shortcut)? Probably unanswerable like speculations about parallel universes or string theory.

Anyway, my thoughts are that games should be fun. Classical physics is often thrown all to hell in the name of fun, why not modern physics? Do what's fun for your target audience. Most people won't care if you throw general relativity out the window, but I realize there are people whose groove is thrown off by incorrect dial placement in a flight sim.

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Quote:
 Original post by Anonymous PosterAnyway, my thoughts are that games should be fun. Classical physics is often thrown all to hell in the name of fun, why not modern physics? Do what's fun for your target audience.

Well that goes without saying, of course. I just thought I'd try and clear up any argument on the subject.

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Quote:
Original post by Sandman
Quote:
 Original post by Anonymous PosterAnyway, my thoughts are that games should be fun. Classical physics is often thrown all to hell in the name of fun, why not modern physics? Do what's fun for your target audience.

Well that goes without saying, of course. I just thought I'd try and clear up any argument on the subject.

Oh, sorry, wasn't directed at you, rather it was in response to:

Quote:
 Original post by SquareDanceSteveAny thoughts?

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When modern science hinders something in Science Fiction, simply make up a new science. Like:

"Dr.Smith descovered energy and matter are actually both made of 'smithies' and 'smithites', and the theories saying that you could not travel at lightspeed was based only on 'smithies', however when 'smithites' are taken into account, the Smith Inversion engine is able to easilly accelerate any object past lightspeeds with no time differentials"

See how easy it is to break laws of science when all you have to do is claim you've done it, and not provide proof?

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Quote:
 Original post by TalrothWhen modern science hinders something in Science Fiction, simply make up a new science. Like:"Dr.Smith descovered energy and matter are actually both made of 'smithies' and 'smithites', and the theories saying that you could not travel at lightspeed was based only on 'smithies', however when 'smithites' are taken into account, the Smith Inversion engine is able to easilly accelerate any object past lightspeeds with no time differentials"See how easy it is to break laws of science when all you have to do is claim you've done it, and not provide proof?

Arthur C. Clarke likes to throw in phrases like "In one of those twists of science..." or "In a coincidence so unlikely no self-respecting author would make it up..." when BSing science. [grin] Sometimes he'll include an appendix with references showing that science might someday actual create it.

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You're writing a game.

Make the "Physics" Consistent, not "realistic".

Consistent means predicatable.

Try and get some Paper, Scissors, Stone element to whatever "additions" you make to Physics. This means Quicker, Cheaper, Better: Choose only 2.

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Quote:

A simple multiplatform library that supports 256 bit registry operations. Like division, multiplication, division by 0, and bitshifts.

It was created in Java, and it should work with any reasonable Java VM that supports at least 4.2.

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Im using visual basic 6, so i guess the lib is out of the question :)

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