Mayhem Orbital Command: The Physics Lab

Games, RP, general Mayhem (within reason, of course)

Moderators: TingYi, anti-paragon, DarkShive

Mayhem Orbital Command: The Physics Lab

Postby Teleros on Mon Oct 15, 2007 6:31 pm

MAYHEM ORBITAL COMMAND: PHYSICS LAB
PART 1: INTRODUCTION & OVERVIEW



INTRODUCTION
This thread is primarily for people who desire a little realism in their science fiction (if you don't, click back now). Whilst the focus will be on real-world physics, various sci-fi elements will be covered, with the objective being to help people create a universe that is internally self-consistent. This is only an introduction mind you - there are much better and more detailed resources online than this!


USEFUL LINKS
Atomic Rockets: An excellent site that takes a hard look at building spaceships and the like.
Metals & Weights: The mass of various metals in kilograms per cubic metre. Useful in calculating for example how much a starship might weigh. Part of a site with various other useful figures and conversions.
Unitconversion.org: One of the handiest sites out there, it has various calculators on it. Want to know how many joules in a gigaton of TNT? Find out here.
Stardestroyer.net: A very good site for proper science fiction analysis, just be prepared for harsh language. "I want YOU for the Galactic Empire" should be your first stop, as it contains a whole bunch of useful information on science and the like. The forums meanwhile have plenty of information on other sci-fi series, from Halo to Warhammer 40,000.
Kinetic Energy Calculator: Has two sections, one for Newtonian and one for relativistic kinetic energies.
Acceleration Calculator: How fast a ship will be moving after a period of a certain acceleration.
Asteroid Destruction Calculator: Works out just how much energy you need to pump in to melt / fragment / vaporise an asteroid of arbitrary size.
Nuclear Explosion Calculator: Just how big will that fireball be?
Stellar Radiation Calculator: How much radiation will hit your ship?
Planetary Parameter Calculator: Working out things like gravity, horizon distance etc for an alien world.


USEFUL STARTING FACTS
Efficiency: You can't get 100% precision, 100% perfect reactions etc etc etc, unless you're willing to play with the Second Law of Thermodynamics (bad idea!).

Force: Force (Newtons) = Mass (kilograms) x Acceleration (metres per second per second). So, 1 Newton is the force required to accelerate a 1kg object at a rate of 1 metre per second squared.

Energy: Measured in Joules. Also remember the Conservation of Energy: if you put energy into something, it has to go somewhere, it can't just vanish. If you bombard an ocean from orbit with your super-powered lasers, then all the energy from the lasers must be accounted for. Some will be absorbed by the atmosphere, but most will be used in heating the water.

Power: Power is the rate at which energy is expended, and is measured in Watts. 1 Watt = 1 Joule of energy per second. So, 1 Joule in 1/10 of a second = 10 Watts. 1 Joule over 10 seconds = 0.1 Watt, etc. To do damage to something though, you need a high energy weapon: delivering a small amount of energy very quickly will not do the job.

Reactions: Every action has an equal and opposite reaction: that's what the recoil is when you fire a gun. You cannot magic this away without violating Conservation of Energy - and if you violate it, you've just built a perpetual motion machine (!). Now of course you can use shock absorbers and the like to reduce the impact of recoil, but the energy is still there, and there will be limits to what you can do without breaking physics.

First Law of Thermodynamics: The amount of energy in a closed system is fixed - ie, energy can neither be created nor destroyed (FYI, mass - ie matter - is technically a form of energy, so don't worry about nuclear reactors etc violating this!). This is important when say dealing with weapons: if you have a kilogram of anti-matter and matter annihilating one another, you simply cannot get more than 1.8e17 joules of energy (43 megatons of TNT) out of it - and that's assuming 100% efficiency of course, which as we note above is impossible.

Big Numbers: Whenever you see a figure like this: "1.1e3", it means "1.1 followed by 3 zeroes", or in this case 1100.


Power Generation
There are probably four main sources of power for most starships:
  • Fission & total conversion reactors
  • Fusion reactors
  • Matter / Antimatter reactors
  • Exotic sources
Fission reactors are fairly well known - they're what power our nuclear subs and power plants. They usually use fuel like uranium, plutonium and the like. A really efficient fission reactor will convert a very high proportion of the mass of the fuel into useable energy - what I've called a total conversion reactor. These are likely only to be built by a very advanced civilisation, but with 100% efficiency you would get 9e16 joules of energy for 1kg of fuel.

Fusion reactors are on the horizon for us today, and use very light elements such as hydrogen isotopes such as deuterium or tritium. 6.2e14 joules per kilogram is the very best energy output you'll get from a deuteriu-based fusion reactor, but such a figure is very unlikely.

Matter / anti-matter reactions will 1.8e17 joules of energy assuming 100% efficiency - twice as much as the ideal total conversion reactor, but at a cost of twice the fuel needed. And don't forget that anti-matter needs to be very carefully confined! However, if you can produce enough anti-matter, and contain it, then this isn't a bad power supply.

Exotic sources can range from other dimensions to the cosmic energy of the Lensman and Skylark universes, miniature black holes and all sorts of other weird and wonderful things, like the Death Star's hypermatter reactor. My sci-fi setting uses what are essentially supercharged batteries, because no ordinary reactor can possibly provide enough energy to power their systems.


Engines
Science fiction is full of a huge number of engine types, but they essentially boil down to two types: reaction drives, and reactionless drives.

The former work by hurling something out the back of the spaceship: it could be plasma, photons (ie, literally a giant laser-propelled starship), chemical propellants, etc.
Atomic Rockets covers the types of engines pretty well: have a look.

Reactionless drives... let's not go there. Really. Honestly.
...
Fine, you asked for it.
The problem with reactionless drives, is that they violate the Law of Conservation of Momentum - ie, in a closed system, the total quantity of momentum cannot change. You can of course have one if you don't have a closed system - but these tend to be boring devices like solar sails or a planet-based laser etc, and consequently aren't very good for deep space.

It's also worth pointing out the problem of manoeuvring in space. Namely, that there's no atmosphere out there. So if you want your starfighters banking and turning like in Star Wars, start inventing technobabble, because it ain't going to happen. Real fighters will manoeuvre like the Babylon 5 Starfuries: that is, they will continue in a straight line until they can say put the engines in reverse and overcome their momentum. Of course you could have a fighter bank by sticking miniature engines all over it, but it'd be horribly inefficient.

Finally, there's another problem with engines. If they're too powerful, you've got at the very least a makeshift weapon. If your spacedrive can get you to Mars in 12 days, it can also do Very Bad Things to other spaceships. Not to mention wherever it's supposed to land.
And if they're really powerful, you end up turning your starship into a planet-killer. Let's say we have a thousand tonne starship travelling at 100,000km/s. If it hits a planet at that speed, it will impact with 5.46e21 joules - that is, 1304 gigatons of TNT - that is, 1% of the estimated energy of the asteroid impact that wiped out the dinosaurs!


Size Does Matter
Sounds corny, but it's true. The bigger the spaceship, the more stress you place on its structure. For example, if you scale a building up by a factor of ten, it will be 100 times as strong... but 1000 times heavier.

It gets worse when you want to build some truly staggering constructions. Remember the Dyson Sphere in "The Next Generation"? Well, it had a 100 million kilometre radius. If we make it out of iron (not that we could, as iron isn't strong enough), and make it 2km thick, it will weigh... wait for it... as much as the Sun. Well, that's fine... until you remember that you're building it around a star. All that gravity as its being built is going to play merry hell with the star you're building it around, and you'll need some super-strong materials to build it too, because of the gravitational pull.

Remember, the same applies to creatures too. If you make a human ten times his or her normal size, he/she will, like the building above, weight 1000 times as much, but the cross-sectional area of her bones etc will only be 100 times as big. Result? Well, you couldn't do many acrobatic moves, and in fact you'd find it very hard to move. Actually, impossible to move, because you'd be dead: your heart wouldn't be able to pump your blood around your body, it'd pool in your ankles, and that'd be the end of it.


Sensors
Look out your window. See the horizon? Of course you do. Now look up into space. See one up there? Nope.

It may sound obvious to some, but space does not have a horizon. Wait long enough and the light show from a space battle at Pluto will reach the Earth. Try and hide your spaceship, and unless you can mask all electromagnetic radiation (like sensors, weapons, the reactors...), your ship will be picked up for certain.

Of course, there are limits: if the resolution of your sensors aren't good enough, then something with a sufficiently small profile will be missed (ie, a missile coming directly at you has a small profile, whereas a missile speeding past has a larger profile).


Waste Of Space
What's a waste of space? Why, the crew of course. If your sci-fi setting has sufficiently advanced computers, then there's no rational reason to have living crew aboard a ship. Crew require all that space-intensive, energy-intensive, mass-intensive life support: cut it out and you have more space for missiles, reactors, armour. And this applies doubly to starfighters, however much we love the image of them zipping around huge capital ships.

Of course, there are workarounds: you may not have sufficiently powerful computers, or the crew may be a cultural hangover the government is unwilling to scrap for whatever reason (I use this excuse myself). Star Trek does it by having powerful computers with appalling security measures: the crew is always on hand to fix the computer when its security is breached.


Shields
Shields are a staple of sci-fi space battles: bubbles of energy that reflect, absorb or otherwise neutralise incoming enemy fire. They come in just about every shape and size, from fields of microscopic black holes to Star Wars' deflector shields and Star Trek's frequency-based shields. For now, let's look at the most common type of shield: an energy barrier that stops attacks.

First off, we have to remember that Conservation of Energy still applies to shields. So, if a physical object (say an asteroid) hits the shields, its kinetic energy cannot simply vanish - it has to go somewhere (typically the shield generator). This sets an absolute upper limit for your asteroid shield: if the kinetic energy is too much, the shield generator will be knocked loose inside the ship!

This also applies even to say a shield designed to stop lasers: because photons have momentum, it's possible for a laser to knock the shield generator loose, even if the shield generator can absorb the energy of the shot.

You should also consider how you intend to fire through your shields: Star Wars ships can open small holes in their shields to shoot out of. Star Trek ships can't do this and so have to use a frequency, timing their weapon shots (rather like how machine guns on early fighters were timed to fire through the propellor blades without hitting them). Ships from the Lensman universe had shields that only blocked incoming fire, so they could fire through their own shields without any problems.


Missiles
Well you've survived the boring stuff, so now it's time to look at the big guns :) . Let's start off with missiles - both guided and unguided.

First off, we have projectile cannons - railguns, coilguns and the like. These aren't actually very good in space, because unless you're fighting at very close range, they'll take a long time to cross the gap - time in which the other side can shoot them down or even simply move out of the way.

Next up we have guided missiles. With no human crew they can withstand some pretty powerful accelerations, and may in fact be manoeuvrable to dodge some point defence fire. However, regular course changes will limit their top speed.

Now for the fun bit - relativistic missiles. These are objects travelling at 1% of the speed of light or faster (so approximately 3000km/s or faster). At these speeds the kinetic energy is tremendous. In my sci-fi universe, the Alliance Navy can deploy missiles that weight just half a ton and reach speeds of 95% lightspeed. Result? 2e22 joules of kinetic energy - about four times that of our thousand-tonne starship mentioned under the ENGINES section earlier.

The one consolation is that relativistic missiles take absurd amounts of energy to accelerate to such speeds.


Plasma Weapons
No! Never!

Ok, outburst over. There is a reason behind that though, which is that plasma weapons do not actually work in real life - unless it is in the form of a particle beam (which isn't really a plasma weapon as most understand it). Unless you're going to employ some handwavium to get them to work, use something else.

Stardestroyer.net has an excellent analysis of plasma weapons and why they don't work.


Energy Weapons
Very broadly, there are three types of energy weapon: lasers, exotic weapons, and particle beams.

Lasers are beams of energy that travel at lightspeed (usually - some universes have FTL forms of energy). Real lasers are invisible unless scattering off something (the target, dust in the atmosphere, etc), but they work by imparting their energy to the target. An infrared laser for example will heat the target up, whilst a gamma ray laser (often called a "graser") will be effective at bypassing enemy armour (because gamma rays are hard to block - hence why nuclear reactors etc have so much protection inside). The good bit is that they operate at lightspeed, making dodging them... hard without some sort of FTL sensor or similar.

Real particle beams come in three varieties: protons, electrons, and neutrons. They may also be called ion cannons, but the key thing is the charge of the particles - positive, negative or neutral. Postively / negatively charged beams however suffer from beam spreading (particles with the same charge repel one another remember), and electromagnetic fields will be an effective defence against them. Neutron cannons and similar however, because they don't carry a charge, will not suffer from beam spreading or electromagnetic shielding.
Because the particles are not massless, your particle beam won't be as fast as a laser. However, you can still expect it to reach a significant fraction of lightspeed if you've a decent reactor behind it, so you'll be imparting a lot of energy onto the target.

Finally, we get the exotic weapons, from phasers to gravity beams. Quite how phasers work is not known (although Stardestroyer.net has come up with a very good theory), but in the official literature they're "nadion particle beams". Gravity weapons like the Xeelee-universe starbreakers are pretty weak against ordinary matter... but can make a star go nova!
These weapons are very hard to quantify in terms of tons of TNT etc: Star Trek phasers are seen making human bodies disintegrate rapidly, but cause damage to starship hulls more consistent with lasers or particle beams (ie kinetic / thermal damage). Starbreakers, as noted, are designed to blow up stars, not enemy starships.


Brain Bugs
Or, common but stupid ideas...
  • Plasma weapons - see above.
  • Exploding consoles. Why the hell Starfleet doesn't use electricity instead of plasma and install some safety features I do not know. It doesn't happen in real life after all.
  • One-dimensional races. You know the sort of thing - all Ferengi are cowardly and greedy, all Klingons are honourable warriors etc. I mean, humans are just like this, aren't they :roll: ...
  • Bioships. Are stupid. A metre of solid metal is just that: a metre of solid metal. A metre of organic armour is going to be riddled with blood vessels, nerves and God-only-knows what else - ie, it's going to be rubbish compared to the inert lump of metal. Babylon 5 really kick-started this I think, but the Vong in Star Wars, Zerg in Starcraft and Tyranids in 40K haven't helped.
  • Quantum technology. Just because it has quantum in the name doesn't mean it's super-duper technology. Quantum torpedoes? Just a meaningless name.
  • Gravity. Is actually a really weak force, especially compared to, say, electromagnetism. The latter makes solid objects solid, the former is so weak people can jump several feet in the air without any problem.
  • Exploding reactors. Especially fusion reactors - the damn things just don't go off like fireworks. Now, an anti-matter reactor might go boom if the fuel leaks into the rest of the ship, but that's what failsafes are for (except on Federation vessels :P ).


CONCLUSION
This has been only a basic introduction to things - in the future I plan on going over several of the points here in more detail, particularly when it comes to weapons - because let's face it, that's the bit we all like when it comes to big starships ;) .
Last edited by Teleros on Tue Oct 16, 2007 4:36 am, edited 1 time in total.
Teleros
Keenspot Juggernaut
 
Posts: 3517
Joined: Fri Mar 30, 2007 4:22 am

Postby VOR on Mon Oct 15, 2007 6:55 pm

Everything there's correct...except your one-line critique of bioships. They can work. They're probably not going to evolve on their own, somebody would have to engineer them (probably a society which developed in very different technological directions from our own), but they can work.

An outer hull would have to be more like the unliving shell of a shellfish such as an oyster than like the bones we chordata are used to: namely, a really hard, relatively inert, stonelike surface. If you're allowing an intelligently-designed bioship (built by a team of alien bio-engineers), it's plausible for it to harness the energy of one of the engine-types you've outlines above for purposes of metabolism, or solar energy if it's operating primarily in-system.
"But first, I must meditate for a time." -Mahasamatman
User avatar
VOR
Keenspot Deity
 
Posts: 11374
Joined: Mon Apr 04, 2005 6:21 pm
Location: The Future!

Postby ChroniclerC on Mon Oct 15, 2007 6:59 pm

It's also worth noting that some ships ( :shifty: ) will have access to magic: the ultimate Handwaviun.
Image Image Image
Image
User avatar
ChroniclerC
Keenspot Deity
 
Posts: 11263
Joined: Mon Jan 09, 2006 4:21 pm
Location: Mad? We're all mad here.

Postby Teleros on Mon Oct 15, 2007 7:04 pm

Yes you're probably right, but "inorganic" technologies tend to be much easier to put to use, and are generally better at what they do than organic versions. If you can make some of the materials on this site, I'd be very surprised if you could find an organic version that's any better.

CC - if the magic has laws etc then it's really just a sort of fancy physics like all that Star Trek subspace stuff... if it's just pure handwavium then get the filthy stuff out of my thread :P .
Teleros
Keenspot Juggernaut
 
Posts: 3517
Joined: Fri Mar 30, 2007 4:22 am

Postby ChroniclerC on Mon Oct 15, 2007 7:07 pm

Don't worry, I always try to have some kind of reality in my magic, although if I need something to absolutely work (or I'm too lazy to quantify it) I'm willing to just say "A wizard did it." But it's my favored tool to fight opponents using absurd amounts of Handwavium.
Image Image Image
Image
User avatar
ChroniclerC
Keenspot Deity
 
Posts: 11263
Joined: Mon Jan 09, 2006 4:21 pm
Location: Mad? We're all mad here.

Postby KylenPhylar on Mon Oct 15, 2007 8:28 pm

Meh. Thanks for taking the fun out of Sci Fi. I'm gonna go play with my plasma sword now. *uses Portals to leave, and puts Teleros into an infinite loop fall.
Avatar By Sanchay. Yes, the Original is back
ImageImage
Because I think I am. As does Nok, who counted the points
~ I know -I'm- not dead, just lacking in the meat department. ~: BinaryWraith

Supreme Commander of Fort Mayhem. Meaning No "My Gun is Bigger" fights, got it?

My ForumFics: The Writer's Pen, Wolf of the Seas
Image
User avatar
KylenPhylar
Keenspot Juggernaut
 
Posts: 9320
Joined: Sun Jan 01, 2006 9:25 pm
Location: Cuddling with Hinata, working on a world domination plan.

Postby vitrial on Mon Oct 15, 2007 8:40 pm

do what DOOM did, put a computer inside the plasma ball with an electromagnetic generator to controle the bolt, simple realy.
i make avatars... just throwing that out there.
Image
User avatar
vitrial
Grand Poobah Keenspotter
 
Posts: 442
Joined: Mon Jun 18, 2007 1:03 am
Location: rock bottom, and makeing the best of it

Postby 10.0.0.1 on Mon Oct 15, 2007 10:09 pm

My 2 cents on this

Applying RL rules to fantasy RPs at best brings in massive amounts of restrictions that will create headaches for both players and GMs.
At worst it renders an RP so complicated you have to quadruple check everything before doing much more than breathing or talking.

Some realism is needed to keep it grounded (the sprit of reality's laws rather than the letter of them if you will) but glossing over how things work makes the story better by keeping the focus on the individuals rather than the technical how of the world. A universe needs to be consistent with it's own rules, if the rules change every week you have a problem. If the rules ignore the formal rules of reality it is not a big deal unless it gets to out of hand.

If you actually try to explain all the details of your universe you end up in the realm of OCBAS (overly complex background anima syndrome) where joining requires you to study what can amount to a small text book.

Ok that tuned out to be closer to 75 cents but still.

Edit: added a link to the OCBAS page
FerretBob: The angry young lady with the hammers is 10.0.0.1
Yun in regards to my RP style: Like the RP equivalent of AC/DC... you play the same character every time, but she's a great character, so we don't mind ^_^
BinaryWraith (Steph from classmates): That was wierd. Not 'sweet transvestite' wierd, more 'sitting in a belltower with a rifle, singing "I've got a lovely bunch of coconuts"' wierd.
binarywraith: What the loligoth. :)
Jonixlord: Does it bother anyone that a girl RPing a guy is getting into a relationship with a guy RPing a girl? just curious.
From Aspects Chapter 8: Ten watched the professor with utmost caution. She trusted this man about as far as she could throw him. Which, given her upper body strength, or lack thereof, wasn’t very far at all.
Yun: Riten himaini ni-Ten, den risenka nige himai (Person-writes not-well Ten, but person-thinks he well)

Kraggi: The fact that you're insulting a majority and not a minority does not make it any more tasteful.
User avatar
10.0.0.1
Keenspot Deity
 
Posts: 11367
Joined: Thu Nov 10, 2005 11:36 pm
Location: 10.0.0.0/24 subnet of the Mayhem Forum

Postby Cameo on Mon Oct 15, 2007 11:40 pm

I aim for my sci-fi to be as hard as I can get it without breaking the plot/other intended results (which includes applying more realism to some elements than to others; throwing out the square-cube law to allow winged people to fly doesn't mean I'll allow there to be buildings or spaceships that break the same law of physics, for instance), so this is really useful. I don't always require that what I envisioned work the same way as I originally had in mind, either, so long as something more realistic can achieve the same results or something different but functionally identical.

However, even though I strive for maximum possible realism and do have a certain minimum standard thereof, internal consistency is even (and considerably) more important than adhering to the real-life laws of physics.

I'm with VOR on the bioships, although I do agree that metal is almost always harder to penetrate than an organic shell.

One-dimensional races (both the ones with a species-wide personality and the ones who just have a single species-spanning culture) annoy me even more than any independent breach of physics possibly could. I'll admit to having done it myself in the past, just to avoid being labelled a hypocrite, but I know better now.

vitrial wrote:do what DOOM did, put a computer inside the plasma ball with an electromagnetic generator to controle the bolt, simple realy.

I don't know enough physics to determine if that would even work, but assuming it does, how do you avoid frying the computer?
ImageImageImageImageImage
I continue to be female!
How devious.
Anyone who wants to draw Cameo can refer to this.
Hooray for avatars I made!
[12:02:17] cameoAppearance: I am an adult. I can make my own ice cream decisions.
The Cammy Guarantee: All sig quotes make sense in context!
User avatar
Cameo
Keenspot Deity
 
Posts: 12719
Joined: Wed Feb 23, 2005 4:19 pm
Location: My Face O'Clock

Postby Reaver225 on Tue Oct 16, 2007 2:21 am

*applauds Teleros* That's quite a bit of material there.. a fairly decent overview of most of the hard sci-fi stuff available.

Just a few points to add or discuss...

VOR wrote:Everything there's correct...except your one-line critique of bioships. They can work. They're probably not going to evolve on their own, somebody would have to engineer them (probably a society which developed in very different technological directions from our own), but they can work.
This is fairly true, however consider a designed bioship that uses the same super-materials as what Teleros stated earlier... what exactly separates it from a normal ship designed from the super-materials? It's 'alive' somehow? Pretty much every function for two different types would be at the least very similar for ultimate efficiency... what IS the difference between the two?

vitrial wrote:do what DOOM did, put a computer inside the plasma ball with an electromagnetic generator to controle the bolt, simple realy.
Wait... so each plasma bolt has a generator that holds together the projectile until it strikes the target?

They have minature generators that are able to hold balls of superheated gas together AND fly in a straight line (because, hot air rises, and superheated plasma would rise faster than a bullet without containment)? AND can force the plasma ball through the air at low velocities? If they've got that technology that can be used as bullets... why don't they just use them in electromagnetic cannons that'd be able to shoot through an entire space station? Why not personal shielding if they've got magical containment devices? It's really, really really really silly. Either they've got supertech to get the plasma to fly in a straight line and don't use it in anything else where it'd be useful, or they're not using real physics.

10.0.0.1 wrote:Applying RL rules to fantasy RPs at best brings in massive amounts of restrictions that will create headaches for both players and GMs.
At worst it renders an RP so complicated you have to quadruple check everything before doing much more than breathing or talking.
This is very true, which is a problem... hard sci fi, unless you have an exceptionally gifted GM AND players, will become incredibly boring, because reality limits a lot of options.
| Mental note: Refrain from using the Force while drunk. | Caption contest winner! | "Screw it. Rocks fall, everyone dies." |
I shall delete you, recreate thyself. - Mutamu
"All citizens to either go to the graveyard and dig up corpses or become corpses for not complying." - hazardswake
Maldraugedhen wrote:That would only be if stupidity was a Boolean thing, or if it was like always multiplying a pair of negative numbers (assuming positive is intelligent).
Stupidity has its own infinite continuum, from bordering on the brain dead to just shy of normal.
...I need to not delurk right after a long coding session.
User avatar
Reaver225
Keenspot Juggernaut
 
Posts: 4771
Joined: Thu Mar 09, 2006 12:38 pm
Location: Spatial error, resetting search pattern

Postby Stardrake_ on Tue Oct 16, 2007 3:10 am

ChroniclerC wrote:Don't worry, I always try to have some kind of reality in my magic, although if I need something to absolutely work (or I'm too lazy to quantify it) I'm willing to just say "A wizard did it." But it's my favored tool to fight opponents using absurd amounts of Handwavium.


Same here.

Like Cameo, I like the science to be accurate where possible - but I'm willing to bend the rules for the good of the story. There's also the argument that we simply don't know everything - what we can't do now may be found to work in the future.

Incidentally, for the record, I tend to think of plasma weapons as being what your essay describes as a particle cannon. The difference in my mind is a particle cannon is homogenous - a stream of electrons, or whatever, utilising the properties of the particle in question to weaponise it. An ion beam is similarly composed just of the ions in question, usually using acceleration through electric fields to impart kinetic energy.

A plasma beam, however, is heterogenous, containing both electrons and positive ions and utilising the properties of a bulk plasma to apply kinetic energy (that's actually something I noticed in the essay. I may simply have missed it, but it seemed to treat a plasma as having the same properties as a gas. I don't remember my plasma physics well enough to pick out if the writer has actually missed something that would destroy the argument being made, but there is a reason its referred to as the fourth state of matter, and my gut feeling is saying that they've missed something - or even several somethings. I'd start hitting the books myself, but I think my housemate is getting a little antsy about the dishes getting washed.

Certainly, though, the Doom-style slow-moving plasma glob is silly, and even a more realistic plasma weapon is going to be relatively short-ranged compared to other options.
"The conflict is not between Christianity and Islam or between East and West - instead, it is between stupid people and other stupid people." - Terry Pratchett

AKA Stellar_Dragon (lost when an attempt to change the linked email address went wrong) and Stardrake (obliterated in the Great Keenspot Crash of '03).

People who are fed up with unreadably small font may wish to look here. For those who POST such text, however, this is not an excuse. Surely 6-pt gets the point across without requiring shenanigans to read?
User avatar
Stardrake_
Keenspot Juggernaut
 
Posts: 5326
Joined: Wed Feb 18, 2004 4:40 am
Location: Department of Paranormal Zoology, Magitech Division, Funky Horror

Postby Teleros on Tue Oct 16, 2007 3:54 am

vitrial wrote:do what DOOM did, put a computer inside the plasma ball with an electromagnetic generator to controle the bolt, simple realy.

Unfortunately not: you end up with a whole bunch of other problems as a result.

10.0.0.1 wrote:Applying RL rules to fantasy RPs at best brings in massive amounts of restrictions that will create headaches for both players and GMs.

To a fantasy RP, yes. To most sci-fi RPs, I think it can actually make things more interesting and encourage creative thinking.

Stardrake_ wrote:There's also the argument that we simply don't know everything - what we can't do now may be found to work in the future.

I think the big one here though are energy shields: I haven't the faintest idea how you'd get one to work (if I did I'd holed up in an MoD lab :lol: ), but I'm having them anyway. Ditto for FTL travel and the like. It's the stuff like conservation of energy you should try never to break though, at least unless you've really thought through the consequences.

that's actually something I noticed in the essay. I may simply have missed it, but it seemed to treat a plasma as having the same properties as a gas

In terms of the problems with containing it it's pretty similar to a gas.
Teleros
Keenspot Juggernaut
 
Posts: 3517
Joined: Fri Mar 30, 2007 4:22 am

Postby RichM90071 on Tue Oct 16, 2007 4:02 am

Teleros wrote:Metals & Weights: The mass of various metals in kilograms per cubic metre. Useful in calculating for example how much a starship might weigh - under one Earth gravity at least.
Or how much it masses, regardless of gravity. Mass != weight. It's worth noting that technically, a kilogram is a unit of mass, not weight.

Interesting concept, but I'm not sure how relevant real-world physics is to Mayhem, which seems to be powered mainly by narrative necessity. However, discussing science as it relates to science fiction in general would be interesting.

Much of the best science fiction combines gritty realism with sufficiently advanced technology. It's most satisfying when the "indistinguishable from magic" is consistent in the way it works. If you can "reverse the polarity" without blowing your gismo up, and you can solve problems by spouting a lot of polysyllabic words that don't really mean anything, then what you're doing is truly magic, and not any kind of science.
He Who Lurks in All Shadows, EGS-DF Hist-Div, Combat Historian. We write history and make it, too.
Updated character bio on the EGS Mayhem wiki
The Lurker now has his own LiveJournal
My own personal wiki: http://richardsindexwiki.pbwiki.com/
My LiveJournal: http://richm90071.livejournal.com/ -- currently uploading info on the ETIA:
Extra-Terrestrial Intelligence Agency
A thin black line between Earth and the rest of the Galaxy
User avatar
RichM90071
Grand Poobah Keenspotter
 
Posts: 264
Joined: Sat Oct 09, 2004 2:30 pm
Location: potentially everywhere

Postby Teleros on Tue Oct 16, 2007 4:36 am

RichM90071 wrote:Or how much it masses, regardless of gravity. Mass != weight. It's worth noting that technically, a kilogram is a unit of mass, not weight.

:oops:
I blame writing it at 2am in the morning :shifty: .

Interesting concept, but I'm not sure how relevant real-world physics is to Mayhem, which seems to be powered mainly by narrative necessity. However, discussing science as it relates to science fiction in general would be interesting.

I'm sure that most of the people here will get along just fine without this - this is for those who are trying to make self-consistent / semi-realistic sci-fi settings. The next bit I'm doing is going to go into various useful laws of science, which are probably the most important things to remember if you're making a universe.
Teleros
Keenspot Juggernaut
 
Posts: 3517
Joined: Fri Mar 30, 2007 4:22 am

Postby Stardrake_ on Tue Oct 16, 2007 5:35 am

Teleros wrote:In terms of the problems with containing it it's pretty similar to a gas.


Actually, that's one of the big differences - plasmas respond to electromagnetic fields, while gases as a rule don't. This is important in containment - in experimental fusion reactors the conditions required for fusion are partially achieved through confinement by electromagnetic fields - the pressure on the internal walls of the reactor is quite low. I'm trying to find references, but not having much luck at the moment - the relevant group at my university doesn't seem to have technical documents up at the moment.

It's also significant where the question of propogation comes up - a plasma will be accelerated in the direction of a diverging magnetic field, for instance, and if subjected to a perpendicular electric and magnetic field will be accelerated in a third direction. This is what makes it different to the 'steam gun' analogy - there are ways to accelerate it, some of which are being exploited to work on plasma thrusters. Of course, there's a big difference between an engine and a weapon - but as Howard Taylor points out at one point, some of the things that are causing problems with getting a thruster to work could actually be an advantage in a weapon.

It is still, however, essentially a particle-beam weapon rather than the plasma bullets that get shown in sci-fi. I actually find it amusing that your link refers to 'familiarity breeding contempt' with sci-fi writers. I think it may actually be the opposite: Sci-fi writers like to use something with properties that aren't well-known except possibly to specialists of the field so they can turn it into bolts that make good special effects without expecting to be caught out. At the time of the Original Trilogy, lasers fit the bill - nowadays, most people know that those green and red bolts do not behave anything like real lasers leading to hypotheses like 'they're really plasma weapons, really!'. Instead of changing the special effects to fit, movie producers instead just changed the name of the little bolt thingies to something else without generally known properties.

Incidentally, going through some of your entries and applying my thoughts:
Reactionless drives: Some forms of FTL proposals essentially rely on bypassing the laws of momentum (and, more importantly, special relativity) - to put it crudely, they move space around the ship rather than moving the space itself in a variety of ways, usually by manipulating gravity in ways that we have little idea of how to actually achieve in practise, but depending on your method of achieving FTL - the Alcubierre warp drive, for instance - you may well end up with a reactionless STL drive almost as a byproduct simply by using it at lower power.

Shields: One thought I've had on generating an 'energy barrier' type shield is through the observation that the reason that solid objects cannot occupy the same space is because of repulsion between the electrons in the two objects. If you assumed a sufficiently advanced control of electromagnetic forces, it might be possible to mimic the fields associated with a solid object without actually having a solid object there.

As some less dramatic forms of shielding, artificial gravity and antigravity are staples of the genre (possibly as byproducts of developing the gravity manipulation technology that allows FTL travel). If you've got antigravity, projecting an antigravitational field from your ship's hull can serve to reduce the kinetic energy of the enemy's weapons and apply redshift (therefor reducing the energy) of lasers or similar weapons.

In a related means of protecting oneself by projecting a 'passive' field could be to generate a magnetic field, protecting the ship in a similar manner as the Earth's magnetic field protects against certain kinds of radiation (something which, on rereading, you've already mentioned in your description of particle beams). Just make sure that the poles are heavily protected. :wink:

Energy weapons: If you can get gravity-based weapons to the point of creating black holes, they will start hurting people. As you said, though, that takes a LOT of energy. The problem is... so does most forms of FTL. By the time you can open a wormhole to an arbitrary point in space, you can plonk a singularity in an enemy ship if they don't have countermeasures.

The saving grace, however, is that if you're assuming a war between FTL-capable civilisations, the target would also have that sort of gravitational control, so you could hypothesise a situation where the difference in difficulty between manipulating gravity and preventing such manipulation is such that it stops being a viable weapon, rather than any battle between two ships simply being a contest over who can put a singularity in the enemy ship while preventing the enemy from doing the same in return.

In situations of gross technological disparity, however, I could see such an attack method being used as the 'with the contempt of swatting a fly' attack.
"The conflict is not between Christianity and Islam or between East and West - instead, it is between stupid people and other stupid people." - Terry Pratchett

AKA Stellar_Dragon (lost when an attempt to change the linked email address went wrong) and Stardrake (obliterated in the Great Keenspot Crash of '03).

People who are fed up with unreadably small font may wish to look here. For those who POST such text, however, this is not an excuse. Surely 6-pt gets the point across without requiring shenanigans to read?
User avatar
Stardrake_
Keenspot Juggernaut
 
Posts: 5326
Joined: Wed Feb 18, 2004 4:40 am
Location: Department of Paranormal Zoology, Magitech Division, Funky Horror

Postby Teleros on Tue Oct 16, 2007 7:17 am

Actually, that's one of the big differences - plasmas respond to electromagnetic fields, while gases as a rule don't.

However, you're in effect just replacing a physical container with an electromagnetic one: the latter still has to be able to withstand the pressure of the plasma.
Teleros
Keenspot Juggernaut
 
Posts: 3517
Joined: Fri Mar 30, 2007 4:22 am

Postby OzLionHeart on Tue Oct 16, 2007 8:25 am

Cameo wrote:...throwing out the square-cube law to allow winged people to fly...


This deserves to be added to the Mayhem Laws of Physics, if it isn't there already.
Image Image Image Image
My inventory/extended profile | My wiki page

"We demand rigidly defined areas of doubt and uncertainty!" - HHGTTG
"I'm supposed to know how magic works?" - Ellen

Ciennas, on my RP style: "I like how your characters can travel through the brink of insanity, catch the reflected light of eternity off of a whole wave of attacking zombie plant things, and still be able to calmly get people out of danger and towards safety."
User avatar
OzLionHeart
Keenspot Deity
 
Posts: 10101
Joined: Sat Dec 03, 2005 4:22 am
Location: Somewhere convenient to watch the action

Postby Teleros on Tue Oct 16, 2007 11:40 am

PART 2: IMPORTANT CONCEPTS & USEFUL FIGURES


INTRODUCTION TO PART 2
This is one of the most useful parts you can read, for three reasons:
1. It explains some of the most fundamental laws of physics - the ones you should be especially leery about playing with.
2. It has the cool stuff like time travel in it.
3. The last section has several very handy numbers for when you're either developing your own sci-fi setting or analysing another one.


The Zeroth Law Of Thermodynamics
"When two systems are put in contact with each other, there will be a net exchange of energy between them unless or until they are in thermal equilibrium, that is they contain the same amount of thermal energy for a given volume."
-Wikipedia

So, if I have a cubic metre of iron at 20
Last edited by Teleros on Mon Jan 14, 2008 3:01 pm, edited 5 times in total.
Teleros
Keenspot Juggernaut
 
Posts: 3517
Joined: Fri Mar 30, 2007 4:22 am

Postby Ajac on Tue Oct 16, 2007 5:01 pm

Nice. But, since I don't think it's been said yet....
OH, GOD NO! The Catgirls, the Poor Poor Catgirls! How could you, Teleros?! WHYYYYYYYYYYYY?!
"Life is actually very simple. We make it difficult."--Confucious.
"IDIC- Infinite diversity in Infinite combinations."--Gene Roddenberry, the Great Bird of the Galaxy.
Q'apla my trekkie bretheren across teh inter-web!
Ut is est Fio mos non planto is Verum.
God wants Spirtual Fruits, not religious nuts.
User avatar
Ajac
Keenspot Juggernaut
 
Posts: 8322
Joined: Thu Nov 16, 2006 7:20 pm
Location: Far flung corners of the quantum universe.

Postby A Fan on Tue Oct 16, 2007 5:08 pm

I've managed to keep the casualties to 50% of what was forecasted. I just had to direct half of the divine wrath to destroying the souls of the already killed catgirls.

...What?
For information on this and other subjects, consult your local ninja.
Best EGS Video. Ever.
Remember: You can't spell combustion without two O's
I had to remove my personality test graph from my sig. You can still see it by clicking these sentences.
If you encounter a strange symbol in my posts, it's from a glitch in my keyboard. I can't see them, so just ignore them. Fnord.
User avatar
A Fan
Keenspot Juggernaut
 
Posts: 4481
Joined: Fri Sep 29, 2006 11:09 am
Location: In front of a computer

Postby Ajac on Tue Oct 16, 2007 5:13 pm

God wrote:Oi! For the record, it's an act of MERCY, not WRATH! Catgirls can't survive in a High RL Physics Environment, and the natural death is...look, you just don't wanna know.
"Life is actually very simple. We make it difficult."--Confucious.
"IDIC- Infinite diversity in Infinite combinations."--Gene Roddenberry, the Great Bird of the Galaxy.
Q'apla my trekkie bretheren across teh inter-web!
Ut is est Fio mos non planto is Verum.
God wants Spirtual Fruits, not religious nuts.
User avatar
Ajac
Keenspot Juggernaut
 
Posts: 8322
Joined: Thu Nov 16, 2006 7:20 pm
Location: Far flung corners of the quantum universe.

Postby Grim Atescu on Tue Oct 16, 2007 5:21 pm

*transforms Catgirls into plushies to protect them*
This is my sig. It is cute. --> @_ *wai!*
The sig likes cookies. --> c@_ *nom*
You will give it cookies, or it will steal your soul. --> @/ *rar*
Beware the cuteness of the sig!
===
"And YOU, Grim, write adorable honeymoon scenes." - VOR
User avatar
Grim Atescu
Keenspot Deity
 
Posts: 17752
Joined: Fri Oct 21, 2005 7:42 pm
Location: Stealing countries with the cunning use of flags.

Postby VOR on Tue Oct 16, 2007 6:55 pm

ChibiMe: ...where'd my army go just now?
"But first, I must meditate for a time." -Mahasamatman
User avatar
VOR
Keenspot Deity
 
Posts: 11374
Joined: Mon Apr 04, 2005 6:21 pm
Location: The Future!

Postby Grim Atescu on Tue Oct 16, 2007 7:06 pm

AnimeMe: *hands ChibiVOR the plushies* Here ya go, I got most of 'em plushified.
This is my sig. It is cute. --> @_ *wai!*
The sig likes cookies. --> c@_ *nom*
You will give it cookies, or it will steal your soul. --> @/ *rar*
Beware the cuteness of the sig!
===
"And YOU, Grim, write adorable honeymoon scenes." - VOR
User avatar
Grim Atescu
Keenspot Deity
 
Posts: 17752
Joined: Fri Oct 21, 2005 7:42 pm
Location: Stealing countries with the cunning use of flags.

Postby ChroniclerC on Tue Oct 16, 2007 11:09 pm

I would assume that the lab is meme-shielded. Wouldn't want to accidentally take out one of your own.
Image Image Image
Image
User avatar
ChroniclerC
Keenspot Deity
 
Posts: 11263
Joined: Mon Jan 09, 2006 4:21 pm
Location: Mad? We're all mad here.

 
Next

Return to Mayhem

Who is online

Users browsing this forum: No registered users and 6 guests