On Creating Imaginary Worlds: Science Fiction

[goldenapples]

And have been asking for 7000 years: Carnac, Stonehenge, Avebury, which is no time at all in Earth terms, recent, in fact. I agree we're irrepressibly sentient because of the imponderable questions.

We've been going that way for years though coping with 'the life force', or the brain that grew eyes in single cell blobs on the ocean floor. We're all linked. We've got it, the blobs have got it. Yahoo!

It's easier than it used to be to 'grow eyes' though. Even as recently as 1000 AD you'd get your arms and legs lopped off just for giving the impression you were conscious through eye contact, asking difficult questions, or having unjustified ideas. I think that's why we like Sword and Sorcery. It reminds us of the struggle to be sentient in an unthinking world.

 

[The Judge]

That's a different angle on it.

Non angli, sed angeli.

 

[J-WO]

I've heard that static (or 'snow') on a tv screen is--in some sense at least--a lingering indicator of the Big Bang. My questions are-

Is this true?

In what sense?

Can anyone direct me to a web site, or whatever, that I can read up more about it? I had a look at TV static in Wikipedia, but there was no mention of the Big Bang.

Any help much appreciated.

 

[J Riff]

This page: Can you explain 'the big bang theory?' | Answerbag, says this:
Well red shift is a good start and also if there is a bang there is often an echo. We found this, a thermal "echo" of the big bang called the Cosmic Microwave Background Radiation. About 1% of the static on your TV is this background radiation if memory serves.​

 

[Ursa major]

So some of the TV 'snow' is the whimper.

 

[J-WO]

Thanks, J Riff!

And interesting point, Mr Bear...

 

[Noob1ett]

Necro sticky time:

Where does one really start in worldbuilding? I have about a dozen loose concepts (some that contradict each other) that I want to include into the same world. Its based around an Apocalyptic event that "changes" things in a sense that the previous political boundaries no longer apply, and from there it gets weird. (there are fantasy and sci-fi elements all over the place in my concept but its more a sci-fi leaning ideal)

Where should I start, or where would be the best place to look for help on determining what I can keep and what I cant to make it a continual world without too much BS?

 

[J-WO]

Well, here's the wikipedia page about it, with lots of handy links.

From the sounds of it, I'd begin with fully working out the nature of the 'changes'- how it looks, the 'science' of it etc- for your world to work, I'd say it's vital to have a confident understanding of this anomaly, because that's the part of your world that effects everything else.

 

[Moonbat]

Ok, I've spent the last three days reading through this thread (not constantly, but between doing important things like eating, sleeping and pooping) and I have seen some amazing answers from our residents.

I have a few questions of my own.

I noticed someone asked if a planet could orbit a black hole, obviously far enough away to not fall into it, although I think I'm right that all orbits degrade over time, but I'm not sure if this was ever answered. If it is possible, and I don't see why not, would the planet get any kind of heat in the form of Hawking (or other) radiation?

I have seen mocked up pictures of large orbiting bodies as seen from a planet, and I wondered how large a body could look before it is too large. Io would have a very large Jupiter in the sky, but it would be too large as Io is so close that it is affected by the gravity to such an extent that it would be nigh on inhabitable. I understand that a planet could be big but not dense, so I'm guessing the answer will also depend on the mass of the planet, but how realistic are large Suns and planets when viewed from the surface of another planet?

We had a great discussion in a thread ages back about the terminal velocity of water, and for the purposes of a waterfall that starts in ice and ends in steam the best suggestion was ice that was travelling very fast from outside of a planet's atmosphere and heating up on re-entry until the friction with the atmosphere managed to turn it into steam. So how could this work, I have supposed two closely orbiting bodies and one somehow (gravity i guess) takes water from the other, I'm sure the other has to asssit in giving it away, so that it accelerates through space before hitting the atmos of the other planet and becoming the eternal waterfall. the other issue with this is how does the water then flow back to the first planet?

ok, that is all for now. But as I am working on the second draft of my first novel which happens to be a comedy space opera, it involves lots of strange places that will require some scientific justification, I maybe back to ask plenty more.

So for you brain boxes out there, be ready to have your brains boxed

 

[chrispenycate]

A planet could orbit a black hole for umpteen millions of years in perfect stability. It would probably be some considerable distance from it, but this is only because the collapse itself would cause major disruption in its vicinity. There's no physical reason why the orbiting body couldn't pass within a few thousand kilometres of the singularity (tides would be something else. It might have to be as rigid as a ball bearing to prevent slowing due to tidal distortion).

I can't see a convenient way of getting radiant energy in a system like this. Hawking energy, from something massive enough to have a planet orbit it? doubtful. If there is enough matter around to form an accretion disk, with some falling into the hole all the time you might get flashes from near the event horizon as atoms were torn apart, but nothing reliable enough for photosynthesis.

With an elliptical orbit you could generate heat energy from kinetic by the aforementioned tidal effects; certainly this would, over a few billion years, cause the orbit to decay slowly; but there's time there for species to evolve, develop technology and telescopes and become extinct.

To get your ice interchange you're going to need two planets with a common atmosphere (see Forward's "Rocheworld" or Shaw's wooden spaceships), and even then it's going to be hard to develop a weather system that concentrates tons of water at the gravitational null, then lets it drift away in sky icebergs which, as they leave the region between the two major masses start to spiral down (sorry, I can't manage a straight fall) until the ice starts to steam, the steam (being lighter than air) rises and is carried to the flying pole, to freeze onto the block…

 

[Moonbat]

Thanks Chrispy

So hawking radiation (or any as yet undiscovered/untheorised energy that radiates from a black hole) isn't going to be bright/strong enough to help photosynthesis, but what about heat? I'm guessing that it is too weak a form of energy to really heat up anything approaching livable standards.

As for the tidal energy, it would create plenty of heat inside the planet (I'm assuming some kind of molten core) but would it also cause massive regular earthquakes (of a scale unknown on Earth (in our recent history) that would hinder any kind of evolution of life?

With regards to the ice interchange, could one of the planets have a supermassive geyser that spewed forth heated water at such a speed that it reached escape velocity (I'm imaginging a fairly small planetoid). I will have to look up the common atmosphere suggestions, but on that note can two planets orbit each other whilst orbiting a parent star? I expect the orbits wouldn't be stable for particualrly long (unless the planets were very far out in the system) but a mergre million years is probably enough for my needs, its more of a galactic tourist attraction than a thriving ecosystem.
But on that note, if very simple life (or even slightly more complex) was brought to a planet that was devoid of life (possibly devoid of fauna) would it be able to find a niche to live in and suvive and then evolve over a relatively shorter time span than it would take for life to develop on its own. I'm also assuming here that we do more than bring a lone bug to a sterile planet and let it loose. Go on little cockroach, do your worst!!!

 

[ktabic]

So hawking radiation (or any as yet undiscovered/untheorised energy that radiates from a black hole) isn't going to be bright/strong enough to help photosynthesis, but what about heat? I'm guessing that it is too weak a form of energy to really heat up anything approaching livable standards.

If the Black Hole has an accretion disk, then yes. Easily. In fact, maybe to much. Temperature somewhere in the region of 12000K (about twice as hot as the Sun). Most of this would be ultraviolet radiation, so pack your spf 1million. The visible light emitted would be bluish-white (the Sun is yellowish-white), but is probably not as bright as the light from the Sun. These should be for a relatively small black hole, somewhere between 3 and 10 times the mass of the Sun.

can two planets orbit each other whilst orbiting a parent star?

Yes, but only becuase of the the planets would be a moon of the other. Both Titan (moon of Saturn) and Ganymede (moon of Jupiter) are larger than Mercury, and if they where orbiting the Sun, rather than gas giants, would be considered planets.
Orbiting a smaller planet is possible to, the Moon isn't that much smaller then Mercury. But it's still going to be a smaller one orbiting a larger one.

 

[chrispenycate]

If you want to start from scratch a cockroach isn't going to make it alone; before you get an oxygen atmosphere, you need photosynthesis. So, green plants, and a few anaerobic bacteria, maybe a fungus spore or two to help prepare the way.

Perhaps a cress sandwich, with the potential of going mouldy…

Or, for a really tough environment to come, a fruit salad containing blackberry pips (can you imagine the animal forms that would evolve from brambles?)

 

[Moonbat]

Thanks guys.

Ok so the black hole needs an accretion disk because it needs to be fed matter slowly so that it can expel some of the energy as radiation. Could this be acheived unnaturally, could a species feed matter into a black hole with intention of heating a neaby orbiting planet? And visible light would be emitted? Hmm, that changes things. Not so much a black hole but a bluish white hole (not as romantic)

but only becuase of the the planets would be a moon of the other

I'm going to assume there is a 'one' missing in this sentence, which basically means yes, but one would be considered to be a moon of the other. How would this be worked out, would it be the larger of the two, or if one was smaller but more massive would it be the planet, I guess it would be whichever was closest to the lagrange (did I spell that right?) point? (or at least one of them).

With the cockroach I was being facetious, but I love your mould cress sandwich idea
But I was thinking more along the lines of trying to get life to evolve, and I mean complex but probably non-sentient life, on a planet that (by our standards of how long it took life to evolve here (easily a billion years or more)) would be considered short lived, mainly because it is in some unstable but more exotic form, like the shared atmosphere.

 

[Venusian Broon]

A black hole doesn't need an accretion disk - but it'll probably have one. Unless it in a dust/gas free part of the universe. Then it'll have used up anything in the vicinity and will be starting to (slowly) shrink. We think.

I always thought, as a rule of thumb, that Black holes and their accretion discs were excellent X-ray emitters. Which would probably not be a good thing for life. Although as Ktabic points out, using a relatively light black hole might work - could rein in production of hard radiation.

Planets and moons - it's an interesting thought, having two 'planets' orbiting each other. Mass is the key thing, so for example the moon is about the quarter the diameter of the Earth but only just over 1% of the mass. So that puts the centre of mass of the Earth-Moon system somewhere near the Earths core.

If you have, say, two Earth sized objects in a pair going around the sun then the centre of mass will be right in the middle between the pair. My guess would be though it's not really a long-term stable solution. If they started out quite close to each other, then tidal effects would turn both places into volcanic infernos, then they would probably very quickly increase the distance between each other as the friction of the tidal effect can only decrease orbital velocity. Then you have the problem of this long 'dumb-bell' increasingly throwing the planet(s) through big extremes of big freezes and scorching summers - not really giving life much of a chance. Finally if the distance gets too great, then other objects would start to nudge these earths apart onto seperate orbits (if not on collision paths or even ejected way out of the system...)

As for life - that's a tough one. We don't really have many other examples to compare and contrast! It looks like life came to earth remarkably quickly once the crust had cooled down - but it was likely to be very primitive. The trouble with seeding a barren world with a more sophisticated bug, is that although there may be a niche for it, I'd guess that it's used to a much more controlled and stable environment - small changes in the environment of a barren world will be much more likely to wipe them all out. The primitive bugs (whatever they were) by definition had to be much hardier. At least that's how I'd see it. I ain't no astro-biologist so don't take the above as gospel!

 

[ktabic]

Ok so the black hole needs an accretion disk because it needs to be fed matter slowly so that it can expel some of the energy as radiation. Could this be acheived unnaturally, could a species feed matter into a black hole with intention of heating a neaby orbiting planet? And visible light would be emitted? Hmm, that changes things. Not so much a black hole but a bluish white hole (not as romantic)

No reason why you couldn't deliberately feed a black hole. Make a great garbage disposal
Getting enough material to a black hole to make an accretion disk would be a hell of a feat. A serious piece of stellar (or even interstellar) engineering. Yes, there would be visible light emited, I'm not sure how much (my back-of-an-envelope calcualtions come out between 1/3 to 30 times the the amount the Sun emits, for a 3 solar mass black hole. I think my envelope is faulty).

Form a planet orbiting the black hole, the 'sun' would appear as a long, thin strip, rather than a circle. From above or below the black hole, it would be circular but diffuse and not as bright. Also, directly above or below the black hole, you would be sitting in its X-Ray emission jet. Not a healthy place.

I always thought, as a rule of thumb, that Black holes and their accretion discs were excellent X-ray emitters.

(saw your reply while writing this one)
It's all down to the mass of the black hole. The emissions are a result of the black holes gravity on the material of the accretion disk. A article falling into a small black hole has less angular momentum and gravitational energy than one falling into a large black hole, so the emission energy from particles around small black holes is lower than large black holes. For small black holes this starts in the ultraviolet range, moving further into the X-ray range as mass increases.
Both smaller and large black holes produce strong X-ray jets from their poles, but that's a different effect from the accretion disk emissions.

I'm going to assume there is a 'one' missing in this sentence, which basically means yes, but one would be considered to be a moon of the other. How would this be worked out, would it be the larger of the two, or if one was smaller but more massive would it be the planet, I guess it would be whichever was closest to the lagrange (did I spell that right?) point? (or at least one of them).

The one with the lower mass would be the moon. It's because a lower mass body (such as the Moon) doesn't orbit a higher mass body (such as the Earth). Rather they both orbit their averaged out centre of mass. In the case of the Earth - Moon, the centre of mass of the Earth and Moon combined is very close to the centre of the Earth, so it appears that the Moon orbits the Earth. But basically the lighter one orbits the heavier one.
As two planets masses become more equal to each other, they start orbiting a point in space between the two planets. But their orbits would become more unstable, and prone to disruption from any third body, like the Sun. The disruption from a third body should be enough to total destroy their mutual orbit in an (Astronomical) wink of an eye.

While checking what I'm writing, I discovered that there is an example of two planets (well, dwarf planets) that orbit a centre of mass which is outside of both planets in out Solar System - Pluto and it's moon Charon. The point they orbit is about 1000km above the surface of Pluto. The reason they haven't smashed each other to bits is because there is still a large mass difference between (Charon is only 11% of the mass of Pluto), and the third, disrupting body, the Sun, is really far away. If you magically transported them to an orbit around the Sun like ours, they would smash each other to pieces in no time.

 

[Moonbat]

Good answers Ktabic and Venusian Broon, Thank you.

I love the idea of the black hole looking like a thin strip of light, it seems to me that it might look like a long neon light strip, and so those kinds of lights would have a nostalgic effect on the people who live on the planet orbiting it, don't worry they will be very hardy and able to survive the onslaught of radiation.

I was thinking more about the waterfall, which doesn't actually have to be water, and element/compound would do, as long as it can begin as a solid and end up as a gas. What if comets from the outskirts of the solar system were to bring large amounts of ice in system with them, the ice then being captured by the planet as the comet passes and raining down, a regular stream of comets might provide enough for regular showers that add to the waterfall. Would it be possible to have some (possibly more than one) orbiting body on such an eliptical orbit that it disrupts the proposed disc of ice (or small chunks of a frozen gas) and brings a trail of it in system to become caught by the planet?
Actually now, I think of it (and I am probably way off the mark) could we have a sort of astroid belt made up of ice that acts like a ring of the planet but slowly bits of it fall in planet (obvisouly faster than the terminal velocity of the liquid to ensure it becomes heated to gaseous state) as the planet orbits? I think I'm clutching at straws here.

 

[chrispenycate]

If you were terraforming a dry,cold (Mars-like) world, it might be practical to have robot ships out in the Kuiper belt fitting drives to small comets and crashing them into your planet, thickening the atmosphere and increasing the temperature with each impact. Not intended as a tourist attraction, no, but that's no reason not to charge entry. This would go on for a century or more, and the thicker the atmosphere is, the more reasonable it is to bring them in on a spiral, burning out by friction rather than impacting and thus causing hurricanes and air shocks rather than earthquakes.

Even with the cloud cover from all the condensing steam it should be a pretty impressive sight.

Saturn's rings are largely ice crystals, so it's not ridiculous to consider a habitable planet getting some. The big problem with these solutions is the small region where there is liquid phase. A big lump if solid ice, with the front of it heated to plasma by friction, and steam boiling off it by the ton; what's the difference between that and a piece of rock? I doubt we can get it clean and homogenous enough that it's transparent, and glitters, nor make the process last long enough that you can have fish swimming around in it; they'd be boiled before they were defrozen.

 

[Venusian Broon]

Both smaller and large black holes produce strong X-ray jets from their poles, but that's a different effect from the accretion disk emissions

.

Yep that's what I was thinking of Ktabic, and as you rightly point out these X-ray sources are highly directional.

Of course you still have a problem of how to explain how to get a planet to orbit on the same plane as the accretion disk. (and closely enough to benefit from the light). If it was a relic of the star system before, and assuming that the new black hole formed its accretion disc in the same plane as the orginal stars, the effect of creating a black hole would surely have fried the poor planet to a very black crisp.

If the black hole picked up a retinue of planets after its creation - then I can't see any strong reason why they would all line up on the accretion disc plane, more likely to go in random, highly elliptical, off-plane orbits and potentially getting close to the bad radiation areas of space. Of course the universe is big and there has to be some planets and things that by luck find themselves being injected into the correct orbit...

Moonbat - Maybe you need to change your ice to get it to work! I mean Titan has rain, clouds, river systems and lakes of hydrocarbons; Venus might have snow of Tellurium; Triton geysers of liquid nitrogen, we think.

A rain/flow of heavy metals might make a nice 'waterfall' effect. If there are oxygen breathing dwellers on the planet, they might not like it though! What about Gallium - melts at room temperature, boils at ~2500K - so may have interesting properties if heating up entering the atmosphere. I don't think it's particulary toxic, although I wouldn't pour it into your cornflakes.

Or a waterfall of diamonds that by the time it reaches the bottom has turned into graphite and carbon dust.

 

[Moonbat]

Interesting ideas Venusian.

Ok, sorry to keep going on, but I did promise some boxing.

With the ice falling into the atmosphere would it necessarily be travelling fast enough to miss out the liquid phase? What if the atmosphere was thinner, therefore causing less friction? As I said it doesn't have to be H2O it could be something else that might have a significantly longer liquid phase. I have no idea how to go about calculating the speeds that anything would accelerate to if falling into a planet. Do the rings of saturn orbit the planet, or are they static, or geosynchronous, would a gentle descent, i.e a low angled orbit give us a longer a liquid phase, although then my waterfall wouldn't be very stright more like a water slide.
This isn't for atmospheric creation, it is purely to try and get the solid/liquid/gas waterfall that would be a hell of an attraction for galactic tourists.

As for the black hole, if the planet did exist before the star went black (or bluish white ) and was therefore hit quite bad by radiation, could it not recover? The accretion disc allows for a longer lifespan of the blakc hole, so could it be possible that a fairly dead planet with only the hardiest forms of life beginning to carve out a niche existing, was then fried to a crisp but a tiny fraction survived and then continued to exist in much harsher enviroment, so then over the millions of years that our Black hole keep pumping out bluish light life regains the upperhand and evolves into something extremely hardy, and a perfect place for a race of galactic villains to live.

I hadn't mentioned this yet, but all my aliens (or at least 95% of them) will be homosapenids, humans that have spread out through the galaxy and been isolated on different planets each then evolving to thrive in the enviroment chosen. This will be over many millenia (possible several million years to give a good degree of genectic/evolutionary diversity) and will be a gradual thing with, hopefully, some humans evolving to breathe in different atmospheres. I want my villians to be so ghastly that they produce their own smog that they choke to life on.