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<blockquote data-quote="Umbran" data-source="post: 7634596" data-attributes="member: 177"><p>Yes. I agree. <em>That's exactly the point.</em> But when you tell them the speed of light, or how gravity scales, you are telling them how the fantasy universe works! They don't have to assume it when you tell them.</p><p></p><p>I meant that a GM shouldn't use the language of real-world physics to express how real-world physics doesn't work. Because when the GM says these things, they are Truth. And players should be able to rely on that truth, and work with it... and as we will see in a bit, that gets ugly.</p><p></p><p></p><p></p><p>Do you know the phrase, "not even wrong"?</p><p></p><p>The thing about the laws of physics is that they are <em>self-consistent</em>, and interconnected. The thing about a fiction in which you change essentially random elements of physics at need to make your magic and game mechanics work is that the result is almost guaranteed *not* to be self-consistent. </p><p></p><p></p><p></p><p>You don't have to be going at almost the speed of light to see relativistic effects. They start becoming easily notable when you are moving at 5% to 10% of the speed of light. If your speed of light is 500km/s, you know what moves 5% to 10% the speed of light? Planets. If you have something like a solar system, people looking up at night will see the effects. </p><p></p><p>More important, if you have a planet the size of the Earth, with a rotational period of about 24 hours... the equator is moving at about 460 m/s - about 0.1% of the speed of your light. The poles will not be. Relativistic effects mean that means that as you move things from the equator to the poles, they will have to rise in mass, and that tmass will have to come from some energy input. How much mass?</p><p></p><p>Doing some quick number crunching, if I have my powers of ten right... for a 1 kg weight, taking it from 0 to 0.1% of the speed of light increases its rest mass energy by about 45000 megajoules, which is 10.7 million kilocalories. Burning 1 gallon of gasoline will release 11 kilocalories. So, to move a thing from the pole to the equator will take... 970,000 gallons of gas above what it does on our world.</p><p></p><p>So, you just created a world in which nothing ever moves north-south! We'd have to question how such a planet could form. You could say, "Well, it isn't even a planet, it is a flat disk on the back of a turtle - the fundamental point has been established anyway, and it'll show up in some way for anything large enough to call a world, whatever geometry you try to dodge with.</p><p></p><p>Well, then you say, we just get rid of relativity! But... that's going to be difficult. Because, you see, that the speed of light is constant is not a *result* of relativity. Relativity is the result of the speed of light being a constant and the laws of physics being the same in all inertial reference frames. And those things are *all* you need for Special Relativity to hold.</p><p></p><p>Oh, so you say, the laws of physics aren't the same in all inertial reference frames!</p><p></p><p>Fine, I say. But, that means perpetual motion machines are possible, which is a violation of the laws of thermodynamics - we have just lost conservation of energy. Which is fine, in a way, as it makes those fireballs easier to swallow. But it does beg the question of why anyone in this world does any manual labor at all - we aren't going to need magic to extract nigh infinite simple mechanical energy out of this...</p><p></p><p>And it is all downhill from there. It would have been better to say that the speed of light isn't constant, or to not name it. Or just don't worry about the speed of light at all!</p><p></p><p>You can have awesome great stories, never mentioning the laws of physics of the world in any detail. I suggest folks do so.</p></blockquote><p></p>
[QUOTE="Umbran, post: 7634596, member: 177"] Yes. I agree. [I]That's exactly the point.[/I] But when you tell them the speed of light, or how gravity scales, you are telling them how the fantasy universe works! They don't have to assume it when you tell them. I meant that a GM shouldn't use the language of real-world physics to express how real-world physics doesn't work. Because when the GM says these things, they are Truth. And players should be able to rely on that truth, and work with it... and as we will see in a bit, that gets ugly. Do you know the phrase, "not even wrong"? The thing about the laws of physics is that they are [I]self-consistent[/I], and interconnected. The thing about a fiction in which you change essentially random elements of physics at need to make your magic and game mechanics work is that the result is almost guaranteed *not* to be self-consistent. You don't have to be going at almost the speed of light to see relativistic effects. They start becoming easily notable when you are moving at 5% to 10% of the speed of light. If your speed of light is 500km/s, you know what moves 5% to 10% the speed of light? Planets. If you have something like a solar system, people looking up at night will see the effects. More important, if you have a planet the size of the Earth, with a rotational period of about 24 hours... the equator is moving at about 460 m/s - about 0.1% of the speed of your light. The poles will not be. Relativistic effects mean that means that as you move things from the equator to the poles, they will have to rise in mass, and that tmass will have to come from some energy input. How much mass? Doing some quick number crunching, if I have my powers of ten right... for a 1 kg weight, taking it from 0 to 0.1% of the speed of light increases its rest mass energy by about 45000 megajoules, which is 10.7 million kilocalories. Burning 1 gallon of gasoline will release 11 kilocalories. So, to move a thing from the pole to the equator will take... 970,000 gallons of gas above what it does on our world. So, you just created a world in which nothing ever moves north-south! We'd have to question how such a planet could form. You could say, "Well, it isn't even a planet, it is a flat disk on the back of a turtle - the fundamental point has been established anyway, and it'll show up in some way for anything large enough to call a world, whatever geometry you try to dodge with. Well, then you say, we just get rid of relativity! But... that's going to be difficult. Because, you see, that the speed of light is constant is not a *result* of relativity. Relativity is the result of the speed of light being a constant and the laws of physics being the same in all inertial reference frames. And those things are *all* you need for Special Relativity to hold. Oh, so you say, the laws of physics aren't the same in all inertial reference frames! Fine, I say. But, that means perpetual motion machines are possible, which is a violation of the laws of thermodynamics - we have just lost conservation of energy. Which is fine, in a way, as it makes those fireballs easier to swallow. But it does beg the question of why anyone in this world does any manual labor at all - we aren't going to need magic to extract nigh infinite simple mechanical energy out of this... And it is all downhill from there. It would have been better to say that the speed of light isn't constant, or to not name it. Or just don't worry about the speed of light at all! You can have awesome great stories, never mentioning the laws of physics of the world in any detail. I suggest folks do so. [/QUOTE]
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