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Original post by Raduprv
The higher the speed is, the less manouvrable(sp?) the ship is. So, yes, eventually, the ship will be VERY hard to control.

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Not true. No matter how fast it is going the spaceship is as manoeuvrable as it is when at rest.

The thing that makes vehicles difficult to control on Earth is not their speed but their interaction with their environment. E.g. tyres are rated up to a certain speed, car suspensions have to work harder at higher speed, steering needs to change direction quicker at higher speed, etc.

Spaceships have no such interaction. Satellites in low Earth orbits slowly lose speed and fall to Earth over the years, but far away from Earth''s atmosphere even this effect disappears. And it''s easy to design things to use air resistance/drag as a stablising effect (from arrows to Apollo launch rockets). Gravity also has a simple effect that does not destabalise objects.

In space there''s no such thing as absolute velocity, so you cannot meaningfully measure the speed of anything alone. Everything is moving relative to something else, e.g. we move around the Earth every 24 or so hours, the Earth moves around the sun every year, the Sun is orbiting the centre of the galaxy, which itself is moving relative to other galaxies.

It''s possible to measure the relative speed of two objects, to work out how long you need to ''brake'' one of them to match speeds. But unless they are intereacting on some way more complex than drag and gravity this will not make either of them ''hard to control''

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Original post by johnb
This is complete nonsense !

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Only for those who didn''t understand what he meant. Read more carefully!

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Original post by johnb
Not true. No matter how fast it is going the spaceship is as manoeuvrable as it is when at rest.

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If by maneuvering a spaceship one means to make it follow a certain path through space, then yes, it will become harder at higher velocities, since the forces needed for the maneuvering will increase in magnitude. At relativistic speeds maneuvering will become ever harder, as the relativistic mass of the spaceship increases.

>> This is complete nonsense !
> Only for those who didn''t understand what he meant. Read more
> carefully!

I did read it carefully. I also posted a brief summary of what was wrong with what was written. If you disagree with anything I posted please state where you think I''m wrong. Don''t just post anonymously implying I didn''t understand what he wrote.

> If by maneuvering a spaceship one means to make it follow a
> certain path through space, then yes, it will become harder at
> higher velocities, since the forces needed for the maneuvering
> will increase in magnitude.

You cannot associate a single velocity with an object in space, as there''s no fixed frame of reference. Each uniformly moving object has it''s own frame of reference, and within this frame of reference the dynamics is the same. If you cannot give an object a velocity you cannot associate properties with it, such as manoeuvrability, dependent on it''s speed or velocity.

You can define the velocity of one object relative to another, and you can then work out the energy required to reduce this velocity to zero, i.e. to bring them together so they have the same frame of reference. A higher relative velocty means this will require more energy but but does not make one or both more difficult to control.

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Original post by johnb
I did read it carefully. I also posted a brief summary of what was wrong with what was written. If you disagree with anything I posted please state where you think I''m wrong. Don''t just post anonymously implying I didn''t understand what he wrote.

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Well, I did in fact state were I thought you were wrong. Your summary was fine, but it didn''t contradict Metoricals post. That''s how I figured you had misunderstood him.

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You cannot associate a single velocity with an object in space, as there''s no fixed frame of reference. Each uniformly moving object has it''s own frame of reference, and within this frame of reference the dynamics is the same. If you cannot give an object a velocity you cannot associate properties with it, such as manoeuvrability, dependent on it''s speed or velocity.

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If, like I said, maneuvering a spaceship means to make it follow a certain path through space, then you do, by definition, have a reference frame relative to which you move, namely that of the path you''re trying to follow. Following that path at a higher speed is more difficult, as it requires bigger forces and more precise timing.

Good sites for information on space physics are sites for information on physics - the laws of physics are the same in space.

In many space sims, ships will slow down when the engines are turned off. This is incorrect. Although it would be acceptable to suppose that the flight computer could be configured to slow the ship relative to some reference frame when the throttle is released it simply isn't acceptable for a ship to consume fuel just because it happens to be in motion.

There is virtually no air-friction in space. There is some 'air' - mostly hydrogen - but it's so sparsely distributed that you would be unlikely to notice it unless you were travelling very fast indeed (relative to the gas, of course).

Lasers are invisible. In gas clouds particles can reflect the lasers. The reflections will take away energy from the laser. This raises two possibilities - a ship could eject a dense gas to absorb laser fire, and in gas clouds you could scan the particles to see if laser fire had been exchanged recently (along the path of the laser the particles would be hotter than their neighbours, and with no air to speak of, it would take some time for the particles to conduct their heat away).

It's not really relevant, but some nebulae do glow. The reflective type reflect the light from the stars inside them. The emissive type are so hot that they are glowing. Being inside an emissive nebulae is likely to be hazardous to your health. I believe you can tell the type of a nebulae from its colour, but I forget which colours the emissive ones tend to be.

It's worth observing that you cannot simulate relativity in a multiplayer game - it's simply impossible. I think you can simulate it for a single player game, but time dilation would mean that at high enough speeds you wouldn't be able to do all the physics/AI calculations quickly enough.

Although position and velocity are relative, you have to store a single position and velocity for an object in order to simulate it. Assuming you aren't simulating relativity, I don't see why you can't select a special frame of reference for anything in the scene and use that for simulation.

With relativity, the issue is that events that appear to occur in one order for player's frame might appear occur in another order in some other frame. This is a difficult enough problem to grok for battle against bots, but clearly there's no way that each player in a multiplayer game can see events appear, in realtime, in a different order - i.e. when one player is sent event A, another should recieve event B: but the server hasn't even simulated that yet.

I don't see how you could cope with the lack of simultaneaty (apologies for the spelling) without having a hairy non-realtime simulator.

Something tangential occurs to me - if a ship moves through a nebula faster than the speed of light in that nebula, it would probably emit Cherenkov radiation, which could be detected. This would mean that a ship moving (very) quickly in a nebulae-based map would be visible on radar even if it had cloaking technology. This is only useful for a game where ships habitually move faster than the speed-of-light in a nebula - an _Imperium Galactica_ style game, say.

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My apologies for recklessly using 'nebulae' as though it were a singular noun.

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Hail Eris! All fnord hail Discordia!

[edited by - Mayrel on November 24, 2002 4:51:05 PM]

JohnB:

I know a ship flying at the speed of light is nonsense but look at how many sci-fi series/films have done it. I thought it might be a relevant thought considering this is a ''game''.

Secondly I think my point was that the speed of light was a constant and therefore the speed wouldn''t cumilate (not that it''s that relevant unless on a massive scale). This is something along the lines of what you said in your summary so I don''t see the contradiction

On a less interesting note:
Also inertial frames suck (a lecturer said it 23 times in one particular lecture ).