Any scubadiver or biochemist to help me with my sci-fi setting?

[Turanil]

Hey! Thanks for all the good answers! Keep them coming! Maybe I will have to do planets with less differences than first intended, but nonetheless, I don't want to create twins of Earth everytime a new humanoid race is created! (Especially when humans encounter an alien starship for the first time, and the aliens speak english and use a technology compatible with that of humans... Despite this, I still love Star Trek anyway).

 

[LightPhoenix]

Well, you can have some vast differences in your planets, because if these planets were colonized "ages" ago, depending on the length of time involved it should be plenty to allow them to adapt to different conditions. The longer "ages ago" was, the more time people will have to evolve and adapt. Outsiders may well need to use a special apparatus to visit these planets.If "ages ago" wasn't all too long ago (say, a thousand years) then perhaps the Ancients also gave the normal mutation rate a little kick in the pants, allowing for slightly faster adaptation, but also slightly higher rates of death (since not all mutations are beneficial).

 

[radferth]

two unrelated thoughts

1) A planets orbit would need to be quite eliptical to have much affect on temperature. Earth's seasons are caused by the angle of sunlight changing due to the axial tilt. The northern hemisphere is acutally a bit further in the summer. Albeit the Earth's orbit only varies by about 1% as to how far we are from the sun.

2) If you want humans to be able to survive on a planet without too much equipment, you want to have the partial pressure of oxygen about equal to Earth's. If we round off and assume Earth has 1 atm of pressure and 20% oxygen, then we have .2 atm partial pressure of oxygen. So if you want a planet with .5atm, you could breath alright with 40% oxygen. At 2 atm you would need a atmosphere around 10% oxygen. I don't know how low you can go in overall pressure before other physical problems occur, but I do know (from watching old Jasque Cousteau) that at high pressures the toxicity of other stuff in the air becomes a problem at high pressures. When they would go down very deep, they would use an oxygen/helium mixture, since helium is quite inert and caused no problems. If you want a high pressure planet, I would suggest having Argon as the main component, as it is inert like helium but has a similar density to oxygen and doesn't make your voice so funny.

Danny -former science teacher, lifetime science geek

 

[CarlZog]

As I think more about it, Turanil, forget about scuba diving. The troubles scuba divers experience with decompression is a result of not breathing gases at ambient pressure. If your adventurers travel to a world with a different atmospheric pressure, they will not have to worry about decompression in the way that a diver on earth does.

However, hyperbaric chambers (which are used to treat decompression sickness in divers) are also used in a growing variety of medical treatments -- including cancers and the like. I don't know much about this field, but raises interesting questions about the ability of diseases, viruses, parasites, etc to be hindered or helped by changes in atmospheric pressure.

To go to a planet with a higher atmospheric pressure could be a boon for some with terminal illnesses that may respond to the higher pressure -- altering the makeup of the population.

Similarly, differences in atmospheric pressure could allow exotic species to thrive and monopolize an ecosystem.

(Diaglo was right about Superman, but we all overlooked it: Yes, what if Superman had really just been a plant or animal -- capable of mindlessly consuming a planet's ecosystem with its newly unleashed super-characteristics.)

There is plenty of real world examples of exotic species destroying ecosystems. Google for zebra mussels, kudzu, or melaleuca in the U.S.

Anyway, a planet would certainly have a vested interest in protecting itself, leading to all kinds of laws, regulations, etc waiting to be either broken or enforced by PCs. Additionally, perhaps one or more of your planets has already experienced these problems, altering the face of it in some unique way. Monocultures tend to be unsustainable and eventually collapse.

All these factors would lead to extensive arrangements of quarantines and acclimatization for beings in interplanetary travel.

Anyway, all these factors would certainly deter the development of a lot of homogenous, cookie-cutter planets.

zog

 

[jasper]

post your question on the t20 traveller site. They will probly give you the formulas.

 

[Jehosephat]

Perhaps you can find some stuff here that would help.

http://www.specficworld.com/resources/world.html

It's got all kinds of resources for world building.

 

[tjoneslo]

Ah the weird question!

So my problem is: I am still working on my sci-fi setting, and there is a few Earth-like planets, with humanoid species. However, I really don't like when some spacefaring dude lands on an unknown planet, and it's the same gravity, climate, atmospheric pressure, and breathable air as in California or Europe. I wanted to tweak that ludicrous staple of science fiction.

My return question to you is, how much science do you want in your fiction?

The key words you want to google on is "Partial Pressure". What determines how breatable the atmosphere is the partial pressure of oxygen. And if the remaining atmosphere is inert enough not to affect the humans breathing it.

For example, the partial pressure of oxygen in our atmosphere is (1 atm * 0.20 oxygen) = 0.20. So on a world with three atmospheres of pressure, the percentage of oxygen need to be about 6% or so.

If the partial pressure of oxygen exeeds 0.3 or so, it will allow almost anyting (including wet wood and flesh) to burn. Conversly, free oxygen does not exist in an atmosphere without a planetary ecosystem to replace it.

Mars: has been terraformed, and has now 0.38 G; 0.5 atmospheric pressure; and air with less dioxide of carbon, but well...

Planet-3: I want an heavy atmosphere for a heavy gravity world (around 1.3 to 1.5 G). Since the planet is far from sun, it would be cold, but heavy atmosphere makes a greenhouse effect, thus retains heat (by the way it is a dim and foggy sky of red color). Plus greater size and heavier gravity give more volcanism, and thus more gases into atmosphere. Hence I was seeing something like a 3 atmospheric pressure. However, how would fare non-native humans there? And how would fare native from this world when on Earth? Ideas about air composition?

As stated above, oxygen is about 5%, which makes it breathable to humans, without too much difficulty. Dust will be a problem, so non-natives may want a filter mask.

Planet-4: I want a bigger but less dense planet as Earth. So 1,1 G; I was thinking of 1,3 atmospheric pressure; I don't know for air: what to have humans and the heavy-world native live without equipment there? Otherwise, it's a world with an elliptic orbit, so summers are insufferably hot, and nothing live in the deserts; sky is pale green.

Tinting air color is difficult. So either don't bother, or don't bother to explan how. The reason is that chemicals that might tint an atmosphere one color or another would be sufficiently concentrated to cause very bad effects on the people breathing them.

As others have suggested, post your questions to the Citizens of the Imperium boards for better answers.

 

[Rel]

I'm with CarlZog in that I think you should forget about the scuba diving angle for the most part. The "Bends" is not something that is of concern if you are breathing air of a constant pressure, even at a pressure higher than you are used to.

One thing that might be a problem however is the higher saturation in the blood of certain gasses. Like Nitrogen. The absorbtion and release of Nitrogen is what causes the Bends when a diver undergoes a rapid decrease in pressure. But the absorbtion also can contribute to a condition known as Nitrogen Narcosis. Essentially it is a feeling not unlike being drunk and it can be dangerous if you're in a hazardous environment.

One story in particular chills me when this topic comes up:

My father (who is a dive instructor) was on a trip to Cozumel Mexico. Much of the diving in Cozumel is what is called "wall diving". Basically you are diving along the edge of an island and the bottom drops off steeply into an undersea trench. As a result you need to pay careful attention to your depth guage to make sure you aren't going too deep because you are without your usual indicator of that condition (i.e. the bottom). My father and a group he was travelling with was on such a dive along with a few other people who were vacationing there.

One woman who was diving with this group started to stray a little too deep and so one of the dive guides came over to her, got her attention and signaled that she should ascend to a shallower depth. She signalled "ok" and swam up a bit. Unfortunately she was probably already starting to fall into the grips of Nitrogen Narcosis. Her mind was not funtioning properly. She didn't adjust her buoyancy any and obviously wasn't paying much attention to her depth guages.

A short time later, somebody noticed that she was missing. The dive guide swam back against the current and looked for her. He spotted her dive light shining around and it was DEEP. He rapidly descended and stopped when he reached around 150 feet. He could still see her dive light and it was shining far below where he was. She was never found and was probably mercifully drunk at the time of her death.

Certain people are more susceptable to this condition than others and that could be the basis for some interesting adventures. Watch the Abyss for an appropriately dramatized story of pressure induced insanity.

Also, always dive with a buddy and abort the dive if either of you starts to feel any disorientation.

 

[CarlZog]

Having been through both the bends and nitrogen narcosis, I can tell you the narcosis was a lot more fun. But then, I experienced the narcosis in a controlled setting as part of a dive training exercise, so I certainly was never in jeopardy like the woman in Rel's story. The bends was another story. Not to veer off topic, suffice to say it sucked.

zog

 

[Someone]

You´ll find that cooking works different in those planets, too.