Questions on space travel for a sci-fi story

[StarkRavingMad]

Sci-fi writer looking for help

Hello everyone. I am working on some ideas for a new science fiction comic... more of a space opera really. I'm not a cosmologist or even a physicist, but I actually can understand (or at least grasp) about half of what I've read on the subject.

I am hoping that I can bounce some questions off these forums to get me on the right track for how to approach interstellar travel and ship mechanics, and maybe get some ideas... like when a Star Trek script just says [...TECH...] for dialogue.

Obviously I don't want to get -too- mechanical. I'm just a storyteller at heart. Basically I want to know enough so that I don't sound like an idiot.

Would this general "lounge" forum be the best place, or would such questions be more appropriate in the Cosmology or Astrophysics forums... assuming they are okay to post at all.

 

[Mk]

General Discussion and General Physics are good, although the mods might want you to stay in General Discussion. Ask as you like.

 

[Danger]

Be prepared to sacrifice accuracy for art. I was a writer myself, specializing in hard SF (until I got on ADD meds and haven't been able to write since :grumpy: ), so I can help you to make something sound quite plausible to a non-scientist. It is a fact, though, that some things necessary for any inter-planetary, inter-stellar, or inter-species story are simply not possible in reality.

 

[Ivan Seeking]

It is a fact, though, that some things necessary for any inter-planetary, inter-stellar, or inter-species story are simply not possible in reality.

This is based on our current understanding of physics which may or may not be nearing completion - likely not. We can't say with certainty what might be possible. We can only speak to the limits within our current frame of reference - within the domain of applicability of today's level of knowledge.

The most interesting thing to come along recently is the Heim Theory, which according to some could make possible an interstellar gravity drive system capable of traveling at many times the speed of light. We began here with links to other threads later.
https://www.physicsforums.com/showthread.php?t=105915
https://www.physicsforums.com/showthread.php?t=106059

Without a unified theory, we can only guess at the absolute limits of physics. There is more information available at this site:
http://www.nasa.gov/centers/glenn/research/warp/warp.html

 

[Danger]

There's no point of me even looking at the Heim article; my math ability is zero. If you and Integral are on board with it, though, that's good enough for me. FTL travel, though, was only a component of the problem. There are also the issues of inertial effects upon a crew during battle maneouvres (Astro's beloved 'Raspberry Jam Delta-V'), the question of how much power can be not only generated, but also safely controlled, in a hand-held weapon, the dispersion of energy beams over distance, the impossibility of building a 'transporter' ala Star Trek, etc..

 

[Integral]

All good SF breaks a few physical laws. The key to "good" is that the author must be aware of WHAT Physical laws are violated, then come up with some excuse (some made up tech etc) which allows the violation. The fewer laws broken the better, the better the understanding of the violation, the better.

Heim theory, should be a rich source of future techs, trouble is very few really understand what Hiem is doing. In a few conversations with Ivan I am very intrigued, but do not know enough, nor am I ambitious enough, to attempt to actually learn about it in depth. It may be a decade before the jury is back on this one. Meanwhile the SciFi writers will be mining this like crazy. Should be a good time for the writers, while the physicist are puzzling it out.

 

[Ivan Seeking]

I don't know if anyone is onboard with Heim yet, but many of us mere mortals anxiously await word from the ivory towers. It seems that the DOD, the USAF, and NASA were interested enough to take a look at the gravity drive concept - a spin-off from Heim's work.

late post. This was in response to Danger. And yes, if Heim has something, it could a very long time before we know for sure.

 

[Ivan Seeking]

Oh yes and Danger, don't worry about g's, after all, all that we need are some Heim gravity compensators.

Transporters will take some time I think...still working on the Heisenberg compensators.

As Michael Okuda (technical advisor on Star Trek) said when asked by Time (28 Nov 1994), "How do the Heisenberg compensators work?" "They work just fine, thank you."

http://en.wikipedia.org/wiki/Heisenberg_compensator

 

[Integral]

So is it time to start work on the improbability drive?

 

[Ivan Seeking]

Not likely...so I guess so.

 

[StarkRavingMad]

Glad to see I sparked some discussion already. I will have to look at those HEIM threads, since I was thinking along the lines of using gravity propulsion already.

Be prepared to sacrifice accuracy for art. I was a writer myself, specializing in hard SF

Oh yeah I know. I don't want to be hard SF. To much time on the numbers takes away from the story IMO. The episodes of Star Trek that seemed only about the numbers just made my eyes glaze over. On the other hand, the times when someone like Michael Stackpole got into the mechanics of X-Wings was really cool, because it wasn't the whole focus.

Anyway... more questions later. Thanks guys.

 

[DaveC426913]

Larry Niven has some good rules for writers interested in sci-fi.

eg.

1] For most advanced sci-fi tech, you will have to tell some lies ("warp drive was invented that can get us to the nearest star in one week"). Tell the lie as soon as possible in your story, so that the readser accepts it as a premise. The bigger the lie, the sooner you should tell it.

2] You must be internally consistent about your lies (as well as any truths). If transporters can detect and beam every atom of an enemy crew member off their own bridge, then sensor technology can sure the heck tell what that crew member ate for lunch.


And other goodies.

 

[Mk]

http://en.wikipedia.org/wiki/Heim_theory
What do you think about that article?

Heim theory as non-mainstream unified field theory? Sounds crackish.

 

[StarkRavingMad]

Both are good advice. I've had a chats with authors at cons that said similar things. Consistency is definitely the key. In essence you are creating your own universe with it's own laws of physics. :)

Larry Niven has some good rules for writers interested in sci-fi.
1] ...Tell the lie as soon as possible in your story, so that the readser accepts it as a premise. The bigger the lie, the sooner you should tell it.

Another approach is the Farscape model. How does it work? It just does.

Starburst is never actually explained, but establishing it up front is basically the same thing as what Niven says here.

But regular ship propulsion through normal space is never explained either. When confronted about this by NASA engineers in the episode where Crichton returned to Earth, he just said... "Then your calculations are wrong."

Can't work for everything, but yeah if you are going to explain it at all, do it up front. My goal is to inject just enough science to keep the story grounded without getting too caught up in it.

 

[StarkRavingMad]

1. Does mass or distance factor into red shift equations?

Specifically, if a spaceship exhausted a large enough energy burst to be seen from a great distance... would the energy stream and the ship appear red as they accelerated toward lightspeed? How fast would it need to go to appear red? Or does this principal apply only to large celestial bodies lightyears away?

2. How fast would a VASIMR drive make a ship go? (asked like a Pakled)

I saw that this kind of magnetic/plasma drive has a theoretical exhaust velocity of 300,000 m/s. But what does that actually mean in terms of speed of the ship? In km/h and % of lightspeed? Assume a freighter sized ship, which I'm thinking would be the size of a destroyer, eg 5500 tons.

3. How much velocity could a ship gain with aid of a magnetic sail helping the engine with the thrust/mass ratio? Same size ship.

4. How much velocity does a slingshot actually add?

Those last three questions can be rephrased... how does a decrease in mass/thrust ratio convert into actual speed?

I understand the concepts, but the math is making my head explode. Be gentle. I got through Calc 1 and 2, but flunked Calc 3 in college :yuck: ... which was over 10 years ago. :uhh:

 

[StarkRavingMad]

One more while I am thinking about it...

5. How much space is between galactic arms?

The ideal spot for habitable planets is in the empty space free of the dust that concentrates in the spiral arms. How wide and long is the sliced area between Sagittarius and Orion, for example?

 

[Danger]

You're rapidly weirding me out here, pal. You passed Calc 1 & 2, and took 3, in college, and yet you're here asking questions that seem remedial. I don't mean any offense by that, but it confuses the hell out of me. I have a grade 9 math level, and never finished high-school, but some of your questions seem like grade 8 stuff. Most of your questions in the last post, for instance, depend upon factors that you haven't introduced. Exhaust velocity, as a case in point, can't be directly related to the speed of the vehicle unless you also specify the mass of the reaction thrust v/s the mass of the ship. The 'slingshot' effect, similarly, depends upon the mass and velocity of the incoming vessel combined with the mass of the planetary body. We need a lot more information before we can even start to assist you.

 

[StarkRavingMad]

Sorry for making the separate thread. Mods keep a tight ship here.

Anyway, I'm not surprised that my questions sound odd. It seems that no matter what subject I try to tackle... I reach a point where the mechanics of it get so overwhelming that it's like my brain shuts down.

Case in point: math. I got A's in my accelerated courses through high school. The downward curve started when I took Calc... then I hit college level math and you could literally hear my brain break down. Any time I get from high end concept down into the nuts and bolts or pretty much anything, I get lost.

What all that means is that I probably shouldn't think so hard about speed because I have NO idea what thrust would be in these kinds of drives. I'm lost on the concept and how to use mass/thrust ratio to determine speed.

And yet I can read Stephen Hawking and follow it!

All I can figure is that I overestimated the size the ship I'd use. It'd be more like 100 tons.

I was hoping that there was a figure for how many times a magnetic sail or a slingshot could multiply any given speed for a ship like that. I am now guessing there is not.

Picking arbitrary numbers out of the air, I was wondering if you had a hypotheical drive that got a ship up to .1c in real space... would a sail get it up to .3c?

From what I understand, a sail or a slingshot are just ways of conserving energy, because they won't require as much thrust to get the same speed... so with the boost, you'd effectively go faster by channeling the engine's output more effeciently.

Or am I completely misunderstanding? Explain it to me like I'm an 8th grader at Star Fleet Junior Academy.

I'm actually most concerned with the redshift question. It's a "minor" detail that affects what I was hoping would be a signature of the series.

 

[StarkRavingMad]

I got wrapped up in the "Blog" thread, and forgot why I originally came here. I'd like to bump this by reposting the main question that I hope can still be answered about redshift...

If a spaceship exhausted a large enough energy burst to be seen from a great distance... would the energy stream and the ship appear red as they accelerated toward lightspeed? How fast would it need to move to appear red? Or does this principal apply only to large celestial bodies lightyears away?

On space travel times, I think I just need to come up with arbitary numbers. The math, factoring mass/thrust ratio is just completely beyond me.

Unless someone can give me a general idea of how much velocity a magsail or slingshot relative to the size of the planet/moon would add to a starship's travel, I'll just wing it and hope I don't sound retarded.

 

[Astronuc]

So is it time to start work on the improbability drive?

That's hard to beat!

But I'd still like to know how Max Quordlepleen got from the Big Bang Burger Bar (beginning) to Milliways. Whatever method he used, it must be very froody!

 

[Ivan Seeking]

Last night I caught one of the new Twilight Zone episodes. It was a play on the idea that androids will one day look and act like, and eventually replace humans.

It struck me that I don't recall any sci-fi that takes this idea through many iterations. Given a few million years, what would the androids build that replaces them, and so on? I guess it would be a sort of super-evolution.

 

[Astronuc]

Wasn't there a Star Trek epsiode (original) that kind of explored that theme. I remember 4 androids, 2 male and 2 femaled. Mr. Scott gets one of androids drunk. And Captain Kirk . . . well . . . does what he use does when women are around. I have to wonder how much of Kirk was Roddenbery's alter ego.

 

[Ivan Seeking]

Allegedly, Kirk was based on the idea of [Marshal] Matt Dillon in space.

And we all know about Matt and Kitty...

...still trying to remember the episode...

 

[Ivan Seeking]

Okay, I remember the scene with Scotty...thinking...thinking...

 

[Astronuc]

I think it was the Saurian Brandy that did the trick.

Spoc was playing chess with the other dude, IIRC.

Ah, found it, but it appears they were aliens - not androids.

http://www.memory-alpha.org/en/wiki/By_Any_Other_Name

The Androids were on the I, Mudd program. They were androids from the Andromeda galaxy, and they were built by a dying civilization.

http://memory-alpha.org/en/wiki/I,_Mudd

 

[Ivan Seeking]

Oh heck, that "I Mudd", with the infamous Harvey Mudd
http://www.treknation.com/episodes/tos/season2/i_mudd.shtml.

Yes, that was still a first super-evolution.


Edit: Ah you know that already.

 

[Danger]

Allegedly, Kirk was based on the idea of [Marshal] Matt Dillon in space.

You missed that just a mite. Roddenberry's thought throughout the creation of the show was of Horatio Hornblower, not Dillon.

 

[StarkRavingMad]

Uhm... Hello? :uhh:

 

[Astronuc]

Uhm... Hello? :uhh:

We were nostalgically musing/reminiscing back about 40 years ago to see what has been done in terms of propulsion and scenarios/missions/plots.

For relativistic travel, one has to be concerned with blue shift in the direction of travel and red shift toward aft.

There is not a magnetic sail that would get a craft to relativistic velocities in a reasonable amount of time. A slingshot or rather a railgun or electromagnetic eqivalent of a catapult could do it, but it would have to be long. In space, it would be preferable to lauch from a heavy body without an atmosphere, or one has to apply thrust to keep the EM catapult stable and in orbit, if it is so.

The problem with a catapult is what happens at the desitination when the craft wishes to decelerate, and also how does one maneuver?

If one has warp drive, the one simply warps around the galaxy or universe depending on how outrageously imaginative or easy one wants to be.

One also might wish to review programs like Star Trek to see what the mass of such a vehicle would be.

I think 100 MT (100,000 kg) is small and offers little protection to GCR. If the trip takes several years or decades, one will want protection from GCR.

I have one of the Space Nuclear Power Symposium (SNPS) publications which might have some farout 'real' concepts, I'll dig around my archives. SNPS was the forerunner of STAIF.

 

[StarkRavingMad]

I have one of the Space Nuclear Power Symposium (SNPS) publications which might have some farout 'real' concepts, I'll dig around my archives. SNPS was the forerunner of STAIF.

Thank you very much.

What is GCR? This sounds like an important factor.

Are you saying that any ship that would be able to cross light years at relativistic speeds would HAVE to be over 100 megatons? That's a lot heavier than I imagine the Millenium Falcon or a especially a Star Trek shuttle to be. Could the protection you describe be theoretically handled by magnetic shielding?

 

[Astronuc]

GCR is Galactic Cosmic Radiation, and you can probably find discussions in the Astronomy and Cosmology sections if you go to that forum and search for GCR. Basically it's high energy particles traveling through space like solar wind, but they can be more damaging because of spallation reactions in the structure of the craft. Then there is the X-ray/gamma-rays from secondary radiation.

No I mentioned 100 MT (100,000 kg) where M = metric. Metric ton is commonly used in the nuclear industry, but I suppose it's easy to confuse with megaton.

According to special relativity though, there is a mass increase associated with matter approaching the speed of light.

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/tdil.html#c3

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/relcon.html#c1

In fact, hyperphysics is a good source to browse for topics on physics and some of the math behind it.

As for a mission scenario - you might want to look into the current status of exosolar planets, e.g. http://www.everything-science.com/content/view/196/1/

 

[StarkRavingMad]

Thank you for those links.

I had assumed that increase in mass was the result of force, not actual mass. See... told you I was a Pakled when it came to this stuff.

 

[Astronuc]

Well, as others pointed out, one can take substantial license with reality in Scince Fiction, with Faster Than Light (FTL) travel, or worm holes, and in the extreme, Douglas Adams has a character who pops in at the End of the Universe (end of time as we know it) from the beginning of the universe (Big Bang).

One has to decide what contraints one wishes to impose on the technology of space travel. Either one goes with real phyics, in which case, interstellar travel takes a long time, or one goes with being able to pop anywhere at anytime, or anything in between.

 

[StarkRavingMad]

Astronuc, I'd like to send you a PM sometime giving a few of the details, just to see if they sound "feasible" in a sci-fi sense. I am going for that middle ground between impossible and grounded. :)

I don't want to post them on a public forum on the off chance another writer is surfing and steals them, because I think they are fairly unique, at least as far as things I have read and watched.

 

[Astronuc]

Sure - all PMs are treated as confidential.