In our physics discussion we run into a problem. On the one hand, physics needs to be unified across the verse to keep things simple enough so the GM's head does not explode. On the other hand, there are a number of past theories which have been discarded, current theories in contention, and future SF novels with radically different scientific theories.
To some degree we can deal with this historically. That is, just say, this is how things were, and are, and then ignore the difference.
In other cases, such as my 'magnetic drive' as in the works of James P. Hogan, we can largely ignore the difference except in special circumstances.
And if we really want to challenge our minds, we can extrapolate through the whole list of changes, and make up a new physics. I've seen MJ do this a bit before. Its hard, and I'm not going to be doing that right now. Although I will say that one of the tenets of publishable game design is to try to do what the ordinary GM cannot to give that GM resources to do something extraordinary. This category seems to fit that rather nicely.
I suspect the best way for most such worlds based on different theory is simply to describe them, and go forward. Ignore theory, and just make the world.
So, I have a long list of unconventional theories. I'm considering doing a set of Parallel Worlds. In one the Laws of Known Science apply, in the other, something that I think is closer to Actual Reality applies.
Let's start with Anthropogenic Global Warming or AGW. This is the idea that Humanity by releasing greenhouse gasses is going to melt the icecaps and raise the level of the oceans dramatically, and probably cause desserts, mass die-offs, and large amounts of underarm odor.
Note: There are a number of AGW expectations. I'm not going to pick the mild ones because That's Just Boring. And yes, this is tongue in cheek. Its more fun that way, and its easier.
In Lutelandas A, the people are hard-working, atomized socially, and profiligate consumers. Its not really their fault for their actions as the Maddies have long ago perfected Suggestive Techniques of Mental Manipulation. After several decades of being exposed to television, the average consumer is so programmed that a graduate of the Insitute of Symbology can effectively make him his puppet in a few minutes of 'innocent' conversation. The result is that the People do what the television advertisers tell them to do.
The Institute of Symbology provides ad-men, lobbyists, music managers, marketing directors and the like for the top-tier companines in the world. It has imitators in other countries, but no equal.
The Council of Oil is another major player in the Lutelandas social landscape. They have bought a variety of technologies, and buried them as these techs would endanger their dominant role in society. When outright buying doesn't work, they can hire The Man, Inc..
The Man, Inc. operatives are conservatively dressed in suit, tie, and white shirt. They are expert at planting evidence, intimidation, gunfighting, and becoming anonymous (hiding, losing a tail, and appearing and dissapearing in a city.) There is a reason they are so good at such things. The Man, Inc. operatives are clones created by an alien commando force in Earth orbit. Their objective is to make Earth spiritually and economically weak to prepare for invasion so they help the Council of Oil and other lesser Business Councils (the Council of Steel, the Council of Soft Drinks, etc...).
Worse, there is the League of Denialists. This League denies even its own existence, and it denies being in the pay of the business councils. In truth, to be a member of the League you must 1)Get a degree in a college in a field related to weather. 2) Sell your soul in exchange for your college loans being cancelled, and guaranteed economic success. Its not certain who they sell their soul too as Denialists are too terrified of the one they call The Boss to describe him. The primary purpose of the League is to come forth and provide pseudo-scientific justification for anything the Business Councils want to do.
But happily there are a few noble forces loose in the land.
The mighty words of the Prophet sway millions every Sunday as he preaches from the pulpit of the First Church of Gaia. He thunders out condemnations. Some of these condemnations have the force of the Goddess behind them, but others require a little help from his friends.
Pax is here to search out the enemies of the people, and help bring them down. They slip into boardrooms, and tape incriminating evidence. They use telephoto lens to take pictures of typical executives dumping toxic waste into the school swimming pool. They tail stretch limosines...but its too horrible to say what those dark cars do.
And sometimes Ultrapax is on the job. A particular polluter is so rampant, a man is condemned by the Prophet, or one is found to be a member of the League, and Ultrapax is on the job. Swift, merciful, and with only one bullet, the Fifemen assasin does his job, and then he goes and unburdens his soul to one of the Goddesses' young, female special assistants.
Of course, for those who are not rampant polluters, but only mild ones, or for mild denialists there are gentler means. The Lutelandas Correctional Facility is there to hold the maladapted and the moderately wicked in their hundreds of thousands behind barbed wire with carbon neutral machines guns to hold back the savages. But, already the temperatures have soared ten degrees, the water laps up Wall Street, Washington DC has dikes to hold out the water, New Orleans is abandoned, and still people won't learn.
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In Lutelandas B, the people are hard-working, somewhat socially atomized although they struggle against it, and relatively happy consumers although they remind themselves frequently that 'stuff isn't the most important stuff'.
The legions of advertisers pat themselves on the back for how they mold the Lutelanders. In truth, the People mostly ignore the ads, and use that time to get ice cream, or to holler at the kids.
The Agency for Green Conservation hands out to pro-global warming scientists a total of a billion dollars a year in grants which comes from the tax money of Joe Six-pack. Joe knows better than to complain however because there are a number of Children of the Prophet around. It is a small, but very active cult, and its members specialize in suing people like Joe for 'Denialism' like 'I don't see why I have to pay that global warming guy on TV with the Armani suit a pay raise when I can barely afford mac and cheese. Why do I have to have a ten cent tax increase on 'all carbon using products?'"
That remark landed Joe in Eco Court where he was ordered to attend a hundred hours sensitivity training, and go to the Prophet's Sunrise Service, and give the complainant, a Ms. Kimberly Martin-Stuart, a secretary at Joe's place of employment a lump sum settlement of fifty thousand smackers for 'causing her gross suffering and anguish by defaming the Earth.'.
Naturally, he tried to go bankrupt.
He was joined in Bankruptcy Court by the reporter who asked a leading GW researcher why that researcher failed to show the numbers he based his speculations on.
Due to the various taxes and treaties and attempts to lower carbon use, the economy was going into a recession. Unfortunately, it looked as if the remedy for a drop of poison was to finish the bottle. The Green Party was very strong.
Of course, anyone, like the leading Nobel prize winning researcher who could not get tenure, or the politician who said 'I'm here to protect the people and the Earth, not just the Earth.' tended to land in bankruptcy court.
There they found that in a new rule that Eco Court rulings could not be evaded by the Bankruptcy Court. Full of gloom, they left to go to a waiting room full of over a hundred clear thinkers. Happily, they did not linger in their gloom for long.
The outer door opened, and several carbon neutral grenades got tossed in.
Enough incidents like that to add to the bankruptcy and job loss and even imprisonment of its foes, and the Green Party won in a landslide.
Then they realized they could not feed enough people organically. There was a solution. It involved opening a work camp in Soylent, Oregon....
And unfortunately, the weather has turned cool as the Sun has entered a cooling cycle. Its not going to bring an ice age, just cool summers and colder winters. Life would be a bit harder, but not near as hard as people were going to make it on themselves.