d20 Future and Hard SF - some random thoughts

[Plane Sailing]

However, one thing we learn from history is that todays scientific certainties become tomorrows old hat. Newtonian -> Einsteinia -> Quantum physics - each step changes the rules. It doesn't completely invalidate the old one (newtons laws of motion work fine for day to day use and calculations, for instance), but the old theories become invalidated at certain points and new ones appear.

You massive energy cost scenario is but one example of thought about FTL travel (which I take to mean 'getting there faster than light does', not 'accellerating past the speed of light'. The latter would be clearly forbidden by the physical laws we know about, the former is why other conjectures can still be considered.

Interstellar Hard SF nearly always allows for some means of circumventing the FTL problem, and then stays consistent within that; the main exceptions that I can think of are those that deal with relativistic ageing (like the Forever war) and those that deal with generational ships (like Non-Stop by Aldiss)

Cheers

 

[kingpaul]

relativistic ageing (like the Forever war) and those that deal with generational ships (like Non-Stop by Aldiss)

I've not read either of those books, so I'm not sure what your examples mean.

Is relativistic aging similar how Card did it in then Ender series? Ender was still alive long after he should have died because of his star travelling. He only aged as long as the trip last, but everyone outside of the ship aged along a normal curve. Similar to the time dilution chart given in d20F

For generational ships, are you talking about where the crew of a ship would have to reproduce so that their children could take over because the trip was so long?

 

[Johnny Angel]

There are stories premised on various ways of getting around the light barrier. At best they end up using technobabble to avoid giving the technology an 'indistinguishable from magic' feel. We bite the bullet and accept the premise for the sake of the story, but we know that it's strictly speaking, if you'll pardon my French, merde de taureau.

Generally, when we're talking about 'hard' science fiction, it tends to be the kind that accepts the cold hard facts as they're currently understood. In those stories, they do not assume you can break the light barrier. Travel is done in generation ships, or using cryogenics. They simulate gravity through centrifugal force in donut-shaped space stations.

I prefer to take FTL for granted, and for that I'm willing to spew a little technobabble.

 

[hobgoblin]

FTL is impossible because we know of no way to increase speed without acceleration. And the speed of light is the position of the asymtote for energy as applied to acceleration. This means it takes infinate energy to reach c. unfortunately the amount of energy in the universe is probably finate, and besides even if the universe had infinate energy who wants to destroy a universe to get somewhere faster (especially considering that somewhere lies within the universe you have to destroy to reach that speed).

the problem isnt acceleration itself, but that to get to anywhere near light speed in a usefull timeframe would basicly put any living beings under so many G's that they would be crushed.

still, i have read a suggestion about a kind of space bubble. so that rather then accelerating a craft and it occupants, one create a bubble of space around the craft. inside the bubble little or no acceleration, outside the bubble one is hitting light speed, atleast

did someone say warp(ing space) drive?

 

[Morgenstern]

Wow. How does the phrase "massive energy cost" get applied to FTL and not to nanotech ? Most treatments of nanotechnology in fiction are simply absurd in terms of the gross violations of conservation of energy.

Work ain't free, and it usually produces heat.

"Inviasion of nanotech using aliens" has the same base hard-sci credibiliy as "necromancers from the dark places cast an evil spell upon the land", given you assessment of Star Wars' plot .

 

[kingpaul]

Most treatments of nanotechnology in fiction are simply absurd in terms of the gross violations of conservation of energy.

Work ain't free, and it usually produces heat.

I always pictured nanotech using the body's fuel reserve (ala food nutrients) when they work. As such, the person with nanobots would need to increase their caloric intake.

 

[hobgoblin]

Wow. How does the phrase "massive energy cost" get applied to FTL and not to nanotech ? Most treatments of nanotechnology in fiction are simply absurd in terms of the gross violations of conservation of energy.

Work ain't free, and it usually produces heat.

"Inviasion of nanotech using aliens" has the same base hard-sci credibiliy as "necromancers from the dark places cast an evil spell upon the land", given you assessment of Star Wars' plot .

trying to put star wars under the sci-fi headers is just wrong, if i can use that word.
there are little or no attempt made at explaining how something works in star wars. the sabers use a special kind of crystal and some vague energy source, the hyperdrive is at best vaguely explained, and so on...

star trek on the other hand is clearly sci-fi as they atleast try to explain why something work when taking todays science and streching it out there...

hard sci-fi would in that reguard be even less out there then the tech of star trek.

 

[Nadaka]

the problem isnt acceleration itself, but that to get to anywhere near light speed in a usefull timeframe would basicly put any living beings under so many G's that they would be crushed.

still, i have read a suggestion about a kind of space bubble. so that rather then accelerating a craft and it occupants, one create a bubble of space around the craft. inside the bubble little or no acceleration, outside the bubble one is hitting light speed, atleast

did someone say warp(ing space) drive?

The problem IS acceleration.
c is <300,000 km/s
1g is ~9.8 m/s^2 acceleration
To reach c at 1g it would take less than 362 days (assuming you have an infinate energy source)
That isn't to long to make it impossible for interstellar travel.

I don't have my physics books to reference for proof at the moment, but as you accelerate a mass towards c, the gain in speed for a given amount of energy becomes less because the mass of the object increases (or more accurately the timeframe in reference to the object slows). The limit of the change in speed as the objects speed aproaches c is 0. It is therefore improssible to accelerate to c. And if you can not accelerate to c, you can not accelerate past c.

Wow. How does the phrase "massive energy cost" get applied to FTL and not to nanotech ? Most treatments of nanotechnology in fiction are simply absurd in terms of the gross violations of conservation of energy.

Work ain't free, and it usually produces heat.

"Inviasion of nanotech using aliens" has the same base hard-sci credibiliy as "necromancers from the dark places cast an evil spell upon the land", given you assessment of Star Wars' plot .

This statement confuses me. You must have some specific idea of nanotech from a fiction source I am not aware of. Nanotech is real, and yes it uses energy and produces heat. However, I won't have to do a matter/anti-matter annialation of an entire universe to say... make a chair or programatically change the color and texture of a piece of fabric. In fact, If I do it right, the waste energy of the process will be less than the conventional means of doing so.

 

[DarkKestral]

3D printers, especially advanced ones, are likely to be a general cost savings over modern technology, and are already capable of operating at the nano-scale. Modern computer chip fabs basically use a modified form of 3D printing to deposit circuits onto chips. They are expensive, but cheaper and more reliable than other technologies.

 

[kingpaul]

The problem IS acceleration.
c is <300,000 km/s
1g is ~9.8 m/s^2 acceleration
To reach c at 1g it would take less than 362 days (assuming you have an infinate energy source)
That isn't to long to make it impossible for interstellar travel.

Oh boy, physics!

Vf = Vi + a * t
300,000,000 m/s = 0 + 9.8 m/s^2 * t
t = 30,612,244.90 s = 354.31 days

Vf^2 = Vi^2 + 2*a*d
300,000,000^2 m^2/s^2 = 0 + 2*9.81*d
d = 4,591,836,734,693,880 m = 2,853,235,066,395.92 miles

So, in that almost year, you'd travel quite a good distance. Of course, I'm not sure what the distances are to the nearest stars are (besides the sun).