A Relatively Hard Game

[dave10000]

[ralphmerridew]

I gave the example above.

A and B agree, in advance, on the following course of action:

They start out roughly the same location.
B signals A by some in-game means (ship's radio, or launching a few missiles); A returns the signal. (This ensures that the two players are in synch.
A travels at high speed to a different location, then returns.
As soon as A returns, B signals A again, with information randomly chosen at that time. (For example, B sees A, rolls a die, then launches that many missiles.)

As a result of time dilation, A's clock will run slower, and A will return (by his clock) well before he returns (by B's clock). (For example, if A travels sufficiently close to the speed of light, A might measure the round trip as taking seconds, while B measures the trip as taking hours. Even if A can't achieve such speeds, any journey will produce a difference in perceived times, and making the journey long enough will produce an arbitrarily large time gap.)

The important difference between this solution and the Chuck's is that, while relativity doesn't rule out time-travel, it doesn't require it, either. However, time dilation is an essential part of relativity.

[dave10000]

I don't see why the "fast round trip" scenario causes a problem. You could have each person's screen have a "personal chronometer." Thus, if A takes action that causes it's clock to read differently from B's, that could be represented by the personal chronometer. To make everything "synch" appropriately, one could have the chronometer show what the apparent time was relative to someone continually at rest at Greenwich, Earth. Thus, everyone would have, say, 2 clocks -- the first would represent their "local" time, which would be the same for everyone, and the second would represent their "relative time" (relative to an observer always at rest at Greenwich, earth).

I'm still at a loss as to why the "fast round trip" could not be modeled in a game. Why can't the game just show them what they would see if they "really" made that trip? In other words:

Can anyone identify specific movements for A and B and actions for A and B that would exist in real life under relativity, but that could not be portrayed (on different screens) for A and B in the game, stating what A and B would see in real life under those circumstances?

[Chuck]

If B moves out and back in several seconds by his clock and A sees that trip as taking several hours then A will have several hours of playing time while B makes the trip. But the player B is a real person sitting at his computer and can't really experience the time as several seconds. While A is playing the game B would have to sit there doing almost nothing for several hours. But B can use that time to review his notes and make plans. The computer can't slow his thoughts. I suppose it could offer him some porn to take his mind off the game but it can't really force relativity on him.

[dave10000]

[gotcha]

If I have two computers at my desk and I am playing two characters, A and B at the same time.
Say, A and B are sitting still around the asteroid belt. And, one asteroid goes past the screen in 1 minute (Both the clocks, i.e. in A's and B's computers will measure this time as 1 minute, and let's say, the clock on the wall also measures this as 1 minute).
Now, I get my brother to hold the controls of A while I take B to a trip around Pluto and back.
Let's say this time should be 5 minutes from A's perspective and 2 seconds from B's.
Now, duting the time I go to Pluto and come back, my brother should have shot 5 asteroids, and that should be an easy task for him rite? coz, the asteroids appear at an interval of a minute by the clock on the wall, remember, he is not moving at all.
And, playing as B I should come back really quick, in 2 seconds. Now, the only way the game could simulate this is by making my clock go really slow, so that, the clock on B's screen should show 2 seconds when the wall shows 5 minutes.
But this means that you can't really travel very far because, it takes 8 minutes to travel 1 AU.

[Celt]

[gotcha]

Yes,

Because remember, B is the one who is moving. When he starts moving, his clock goes awfully slow and B experiences not whole lot of time, but I the human player playing B will have to wait a whole day to make a trip just around the solar system. OBVIOUSLY , this is not practical.
But, there is another problem. Suppose, B decided to destroy hmself and headed toward the Sun at the velocity of light. In a real situation, B would never get an opportunity to change his mind, he would be in the Sun as soon as he headed toward it. But, in this simulation, there would be plenty of chance for that. Doesn't that count as a paradox ?

[dave10000]

[firemedicntx]

Ok, all computer jagon and server probs behind. This game is based on relativity. If all the laws of physics and relativity were applied to this game in theory. It could never become a reality, most of the explaination to this game is fluff. If this was a multi player game and if ship A accelerated to or as it approached the speed of light. It would exsist in a plane of its own, leaving behind the game and the players. Upon return, that is if return is indeed possible in current theory. There would be no game, the user would be dead and ship A would not have a computer upon which to exsist anymore. Thus ending the game briefly for ship A but a lifetime or more to the user.

Just the first thought that came to mind upon reading this. I just found this site. Thought it was an interesting question.

[ewan]

I think this game is possible and the riddle is either a trick (you cant post the check back) or a mistake.

take the ship A flys to puto and back A time = 5 min b time = 2 hours
as A accelerates A's in game clock starts slowing down so that when ship A returns the in game clocks of A and B no longer match

anything we can calculate with the equations of relativity, such as 'how much time should pass for X going at speed Y' can be repersented by doing those calculations on a computer and displaying ther results.

to make things easier the server would have an arbiratry rest frame from which relative clock speeds would be calulated to be displayed in player time.

take the crashing inot the sun example, as the player accelerates towards the sun his clock slows down, so this might apparently casue a problem, since the player has plenty of tiem to change course, make a cup of coffe etc when to be fair to the other player he should not be able to turn out of the way in time.

However, the server would simply make the time actions take to process longer depending on the in game speed of the ship in question. he player diving towards the sun franticaly clicking the 'turn away from sun' button would see his in game finger slloooowwwllly move towards the controls of his ship.

take the players get old and die before anythign happens question.

well this simply depends on how fast the game clock runs, if you move att eh speed of light from one side of the room to the other then no-one will die of old age. if you go on a trip to alpha centurii or are flying around the solar system then the game clock needs to run quite fast, a month of rest frame time per turn for example. but this is normal for many games.

what realy causes problems when trying to program relativity into games is the processing power invloved which expodentialy increases with the complexity of your game, ie. for exach ship or other object you add you have to model the entire universe again as seen from that object. (A shines a torch at the asteroid, when does B see the reflection)

but with a simple game, two ships and laser guns I think you could do it.

[Celt]

You took the words right out of my mouth.
^{(Apparently after I had chewed them a little.)}

[IWTGBTP]

Is it supose to be a red shift not a blue shift?

[ralphmerridew]

Objects moving away from you are red-shifted. Objects moving towards you are blue-shifted. In astronomy, almost everything is moving away from Earth (the Andromeda galaxy is an exception, IIRC), so they primarily talk about red shift. He specifically mentioned "incoming missile are blue shifted".

[What if...]

Haven't been here in forever... Oh, well, since I am too lazy to see if someone else wrote this beforehand, I'll just say some things. 1. If you tried to use general relativity, too, and you can move many large bodies, it might be difficult for you to take every thing into account. Of course, this doesn't matter for most just shooting things. 2. If you have the computers show the perspective from an absolute frame of reference, but the ships experience the time dilation, etc., it should work. Your perspective and the "pilot's" aren't the same. Third, if you could actually move the people into intense gravitational fields and accelerate them as they play the game, it might be easier (or might not...).

[Cristian]

Hello !

ME B new , so dont yell at me for beeing wrong :

Firstly relativity and realism are free for anyone to have ; you dont sell them. SO the author would have no case at all against the man "stealling"
his idea . Relativity wasn't discovered by him , and wasn't made by him either. So BOO to him .

Second, I doubt anyone would read up in the game`s database or somthing about what relativity is about ; the educational purpouse falls. Nobody would now it`s a more calculated game , they all would just want to play it, not read it`s "DNA" .

THat`s it for now

,Cristian

[Burning]

[Burning]

[Celt]

[Burning]

[dave10000]

[Burning]

[dave10000]

[zedmango]

The time dilation solution is right on. The problem with the suggestion to slow down time at different rates for each player is that to slow them down at the right rates, you would have to exactly cancel out the relativistic effects of time dilation, so you would effectively be playing a game in Newtonian physics, at least in terms of time.
It's not a trivial answer at all. It's one thing to speed up trivial tasks in a game, but this would mean you're no longer simulating that aspect of special relativity at all.

[dave10000]

[zedmango]

[dave10000]

[ewan]

I agree, the sdolution or error should be posted.

I think that this riddle has come from a time when multiplayer games were played on a single computer with one screen. The real life game it is obviously aluding to is space wars, where you have two ships and a gravity well and thrusters and they soom about in newtonian physics style way ina 2d eviroment

Obviously if this game were to be 'improved' by the addition of relativity you would be unable to represnt both ships to the single 3rd person view of the screen and have the players identify with thier invidual ship.

however if you split the screen or use two computers connected over the internet as modern games do then an ingame clock solves all your problems as you can show a differnt 'view' from each ship, just as you could calulate with pen and paper, what the lorenzt contraction, apparent position of object would be from any given rest frame

[dave10000]

First, a thanks for posting the solution.

Second, a suggestion that the solution is kinda lame.

It's clear that in order for there to be multiple players, they can't be able to communicate. For instance, we know that A might see a missile as red-shifted and B might see it as blue-shifted. So, they need to have different computer screens. But if A is allowed to see B's computer screen, A could see the missiles as red-shifted *and* as blue shifted. So, we must ensure that A can't see B's screen. Similarly, A can't receive any information from B (in "real" time), else there are faster-than-light issues.

The official solution states the problem is that: "In a multiplayer game, there's no way to guarantee that players won't talk to each other in the "real world" . . . " Huh? Of *course* there is. I've played many games that do just that. You play at some centralized location, and each player gets his own pod. Or even perhaps not a centralized location -- perhaps there are stations all over the world that match people up at random and thus as a practical matter prevent communication during the game. So, out-of-game communication is an issue that must be dealt with, but it is *not* one that is impossible to overcome.

In addition, the situation is not nearly as drastic as the solution suggests. One of the rules of the game is that no one can talk to (or receive any information from) another player (or another player's machine) while the game is in progress. As long as all players followed those rules, then everything would be fine. The fact that *sometimes* players might cheat and thus screw up a particular game does not mean that the entire game, for everyone else and for all time, is worthless. It's *easy* to cheat at games if one is inclined to do so, but those games still exist. For example, "out of game" communication (very loosely defined) in bridge is prohibited, but most people respect that and the game reached Beta a long time ago. Those who do engage in out-of-game communication (secret agreements, signals other than with bids or cards, etc.) ruin the particular instance of the game being played, but do not prevent the game from existing as a meaningful game for those who *do* follow the rules. Same, I think, for Relativity Wars, unless I'm missing something.

In any event, I view the solution as identifying a problem that must be dealt with (and there are, of course, *many* of those) rather than an issue that prevents the game from existing at all. Thus, to me, the official solution is fairly unsatisfying.

[ewan]

I have a new puzzle

bob has a new game idea its like counter strike, but an additional radio jamming device is available for players to use. why will this game never get past beta?

[Zarriar]

I still think it is theoretically impossible to model relativity in a multiplayer computer game.

Let us assume that the computer does handle time dilation by speeding up the clock of the slower moving players. This would mean that slower players would have constant instantaneous feedback on the speed of the fastest moving player in the simulation regardless of the apparent distance between players in the game world. This is effectively information travelling faster than the speed of light. Even if some random element was added to the speed at which time passed for each player you, would still have a sense for how fast your opponents were moving.

If the computer doesn't handle time dilation in this way then what other options are there?

[Lord Ike]

What do you do if you have the sudden need for a bathroom? You shouldn't be able to log out mid-battle, so do you go just become a sitting duck to be fragged at light speed with no resistance whatsoever?