Science question.

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Phasmatis
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Science question.

Post by Phasmatis »

This isn't for a hard science world but I would like to base it on some semblance of realism.

If a device for manipulating mass and gravity were to be invented (I'm worried I'm getting into Mass Effect territory here), this would partially lead us to long distance space travel because travelling faster than light leads to infinite mass and requires infinite energy, I think, please correct me if I'm wrong. If the mass manipulating device could some how change a space ship's mass to a negative number, theoretically this would allow the ship to travel FTL and if the ship has no mass then it shouldn't collide with anything, as stuff would pass through it, do I have that right?

I just had a look at a Mass Effect wiki and the Mass Relays; "create corridors of virtually mass-free space allowing instantaneous transit between locations separated by years or even centuries of travel using conventional FTL drives." which isn't what I'm doing exactly but it's similar which is annoying.
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Re: Science question.

Post by Phasmatis »

I was ill yesterday and posted this while on co-codamol just before I went to bed and it seems I didn't finish the post. Basically I'm asking if what I propose sounds plausible in a sci-fi setting?
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Re: Science question.

Post by Jonas »

As a non-scientist at least, that sounds convincing enough for me. But also as a connoisseur of Science Fiction, I would note that if there's a device that can manipulate gravity, it can probably also be used as a weapon, which could potentially be kinda cool. I've seen it in other works, "gravy guns" that can crush another ship just by increasing its mass to hideously unsustainable levels, and I'd love to see a gravity weapon in a videogame.
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Re: Science question.

Post by Phasmatis »

Thanks Jonas. What I have planned doesn't actually involve combat but I do like the idea of a gravity weapon or at least using the gravity manipulating device as a weapon so I may have a think about that.
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Re: Science question.

Post by Jaedar »

Phasmatis wrote:If the mass manipulating device could some how change a space ship's mass to a negative number, theoretically this would allow the ship to travel FTL and if the ship has no mass then it shouldn't collide with anything, as stuff would pass through it, do I have that right?
So, there's a couple of things I'd like to say.

First of all, negative mass. As far as we know, no such thing exists, and because of this, we really don't know what would happen. It may be that it would just be a - sign in all the equations, it may be that it would make us take the absolute value in all equations, or a mix thereof or something different. The negative energy states of matter that appear when you solve a particular differential equation in relativistic qmech are usually just interpreted as anti matter, but as far as we know, antimatter masses behave like regular masses(although this has not been properly tested yet).

As for collisions: the collision is essentially 2 objects doing forces on eachother. If one of them has negative mass, we don't know what would happen, as above. If one has 0 mass you can't really interact with it a lot, so odds are yes, it would just pass through. However, to accelerate something you have to apply a force, so I don't know how you'd set a massless object in motion, nor how you'd slow it down. There's particles in nature with ridiculously low mass (neutrinos) and these basically don't interact with anything. But as I think more about it on the fundamental level you view it as the atoms and particles creating virtual particles by breaking the conservation of energy(in accordance with the uncertainty relation) and I guess regular particles would do that all the same.

As for 0 mass allowing you to travel to FTL speeds: Probably not. There's a good youtube video about this but I can't find it right now. Basically, photons have 0 rest mass but all this does is force them to travel at speed of light. If you were to cancel the 'increase in mass' from going really really fast, you would still probably need infinite energy to go faster than the speed of light.

tl;dr mass is fucking weird.

If you actually want to have FTL, go with bending space time to shorten your distance imo, that's at least theoretically possible.

Also don't forget its science fiction ;)
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Re: Science question.

Post by Phasmatis »

Thanks Jaedar. The whole antimatter thing worries me, if the ship can have negative mass would it not collide with antimatter which also has a negative mass (theoretically), which would obviously cause problems when hurtling through space and of course like you say, how do you apply force to massless object anyway. AND this very mass effect like, maybe I'll look into something else.

I didn't go for the bending of space time approach because it's been done a lot but that's probably because it's theoretically possible and quite easy to visualise.

Hmmm, what if I married to the two, sort of. Start the ship moving towards the speed of light then shift the ship into another dimension and in this dimension the ship can travel faster than light because the physics for mass and gravity are different. The contents of the ship may be an issue for that though. what happens to the people on board, this might be too complicated for it's own good.

The ship needs to travel for days to get to other systems for my story to work so wormhole technology is kinda out of the question, unless they have to travel for days to get to the wormhole of course, kinda like Stargate or the X games.

Well I've got few possibilities to think about now, which is good.

By the way if anyone does have a passing interest in physics, I recommend http://sixtysymbols.com/, it's awesome!
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Re: Science question.

Post by Jaedar »

Phasmatis wrote:The whole antimatter thing worries me, if the ship can have negative mass would it not collide with antimatter which also has a negative mass (theoretically),
Antimatter does not have negative mass. It has regular mass. As wikipedia states: "In particle physics, antimatter is material composed of antiparticles, which have the same mass as particles of ordinary matter but have opposite charge and other particle properties such as lepton and baryon number"
Phasmatis wrote:Hmmm, what if I married to the two, sort of. Start the ship moving towards the speed of light then shift the ship into another dimension and in this dimension the ship can travel faster than light because the physics for mass and gravity are different. The contents of the ship may be an issue for that though. what happens to the people on board, this might be too complicated for it's own good.
Make the other dimension hell and let the ships have a force field powered by god and you've got warhammer 40k :) (sort of)
Phasmatis wrote: The ship needs to travel for days to get to other systems for my story to work so wormhole technology is kinda out of the question, unless they have to travel for days to get to the wormhole of course, kinda like Stargate or the X games.
Well, I don't see how that is an issue, why do the wormholes have to have entry and exit points right next to planets? If the travel time needs to be days just have an explanation for why wormholes typically appear days away from inhabitable planets?
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Re: Science question.

Post by Phasmatis »

Oh, I thought I might be a bit confused about antimatter oh well.

I think you're right, wormholes are probably the best option. I thought about using a fusion engine type thing where the engine makes a small star using hydrogen, I know there is something like that being worked on in the real world so perhaps these wormholes could use the star of each system as a means of power, in which case the ships need to travel from the habitable planet to the wormhole. If it takes 8 minutes for the sunlight to reach us then the ships could be relatively slow and not require a huge amount of energy to move.

This won't be seen in the game or anything but I do think it's important to have a lot of background information, if the wormhole can only be a certain size that means the ship needs to be a certain size, the engine doesn't have to be huge now either and I'm sure it will effect other stuff too.

This is awesome. Thanks Jaedar and Jonas!
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Re: Science question.

Post by fantsu »

You should not read mass effect wiki, just the Bible. It will explain you everything you need.
Antimatter would have been mentioned in it, if it really excists.
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Re: Science question.

Post by G-Flex »

I have no idea if the above post is a joke or what, but antimatter does exist and has been produced artificially, albeit not in large quantities at all. It's also produced naturally in minute amounts in the form of positron decay (used in PET scans).
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Re: Science question.

Post by AEmer »

Mass Manipulation is a decent way to envision FTL.

Speed and mass are interlinked; there's not really any difference in the gravity pull a fast object excerts, and the gravity pull a heavy object excerts. Reducing the mass is the equivalent of increasing the speed.

Of course, there's also relativity; you can't make two objects move away from eachother faster than the speed of light, that's the law we know, but there's also another law: The metric expansion of space.

Basically, if I'm standing 2 meters away from you now, then in a second, I'm standing more than 2 meters away from you; except the size of a 'meter' itself has also, in that time, expanded, meaning that I'm still standing 2 meters away from you.

Zuh? you say. So what does this matter? you say. It matters if there's so much space between us that, in the time it takes me to move a lightyear towards you, the distance increases with more than a light year. You will in effect, then, be outside of my event horizon; beyond my capacity to ever reach or affect.

This is important, because it's the reason the universe is not 13.3 billion lightyears accross - the 'observable' universe is hundreds of billions of lightyears, because everything has moved apart because, well, everything (including distances) has grown, whilst the speed of light? has remained the same. Or something. I'm not entirely clear on it, but it's effect is very real.

The important thing is, space itself isn't just empty, it's a property, an object which has size and so on. Now here's a question: Could an object beyond an event horizon have to adhere to the laws of relativity with objects on the other side? No. No it could not: Then information could escape beyond the event horizon, which means it would have to move faster than the speed of light. Which can't happen. So.

If you want to break the light speed barrier, and not to sound like mass effect, you can use gravity manipulation to get to the speed of light pretty easily, but you have to break space itself to move away from anything faster than the speed of light. So what do you do? You _dissappear_. You move beyond an event horizon from the point of view of the rest of the universe, and then you are no longer on the same plane of existence as the rest of the universe, therefore you do not have to obey any laws of relativety to anything that still exists there.

In a sentence, you go through the Tannhauser gate. Source in a bit of very famous monologur from the 1982 film Blade Runner, the Tännhauser gate is a concept the anime studio Gainax introduced in their anime 'Gunbuster', and it's a very sciency little thing that's just the black hat for your rabbit to disappear into:

It's two singularities (the center of a black hole), caught in a pulsar-like orbit that is so rapid that the schwarzchild radius 'orbits' them in a torus-like shape, and the singularities themselves are 'naked', because their fast movement makes their gravities cancel eachother out. Spaceships in gunbuster supposedly travel through this 'hole' in the 'ether' of the universe in order to achieve warp.

So. Have your spaceship have two points at geometrically opposite sides of the ship, have it spin (rotate) rapidly, have it within a gravity reduction field to the point where it's travelling at the speed of light, then make two artificial singularities (using gravity manipulation) at either the two points to 'dissappear' from reality altogether, and boom - FTL. To the rest of the galaxy, the FTL ship is simply a stream of dark energy, flowing outside of anything and everything, which appears to coalesce at it's destination moments after disappearing from it's origin.

And don't worry about ripping off gunbuster. For one, bad artists imitate, great artists steal. Secondly, gunbuster is a 30 years old direct-to-vhs anime that was only released in japan, was poorly animated, and which itself ripped off Top Gun and some...tennis anime or other. Trust me. Not stepping on anyones toes here.
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Re: Science question.

Post by AEmer »

fair enough :-)

To me, tieing the idea of an event horizon together with FTL is just so neat. You could do the same thing with stargates; same basic concept. They'd just be big structures disappearing stuff.

Fusion is totally realistic by the way. You can both do it via fusion thrusters (which is pretty cool), or you can do it using some kind of amped up electro thruster (generating thrust by accelerating a steal of particles).

Noone will think twice about either.
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Re: Science question.

Post by Phasmatis »

I think I'm going to have to go with a wormhole at each system's star and propulsion. The main ship is a passenger ship so seeing outside the ship is something I would like and having the ship as a rectangle helps with the design. There are small ships too and these need to be able to travel systems like the larger ones so a simple-ish fusion engine would probably be more readily available, thanks for the idea though.
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Re: Science question.

Post by DDL »

This is basically Iain M Banks' Algebraist universe: a whole galaxy of connected wormholes located a gravitationally zero positions (so lagrange points, deep space etc). All other travel uses conventional physics, so it can take a day to jet over to a wormhole in the same system, then no time at all to leap to the other side of the galaxy.

Plus it means that if your wormhole gets destroyed, you're cut off from everything until they can ship over a new portal at conventional (sublight) speeds, which could be hundreds or thousands of years.

Artificial gravity is always an awkward proposition, and mass effect's silly handwavy explanation is a terrible example of such. It's basically "we really want there to be a consistent DOWN on our spaceships for ease of game design" (replace game design with set design for sci fi movies). Gravity isn't a linear field, and obeys the inverse square law: the only reason you don't feel markedly heavier on the ground floor of a building vs the tenth floor is because the distance from you to the centre of the earth is a much, much greater difference than ground vs 10th floor, so the proportional change is tiny. In a spaceship like the normandy, you could be anything from RIGHT NEXT to the A-grav centre, or...something like fifty times further away. In shepard's cabin you'd feel floaty, in engineering you'd be close enough to detect differences between your feet and your head. And if you fell through a hatch and landed on the field centre, you'd be instasquished.
They wave this away with 'linear A-grav fields', which make even less sense (how far out do they propagate? Do they fall off linearly, with the inverse square, or even at all? Are they doublesided? This would mean ordinance launched from the underside of the normandy is essentially escaping a gravity well every time), and suggests that gravity fields can have edges, which is all kinds of strange.

Admittedly I'm in love with rotating frames of reference as a gravity substitute, so I'm biased, but hey.


Anyway, if you're not going down the wormhole route, then the pseudo-mass effectian idea of corridors of masslessness or similar isn't a bad idea. Something like a ship generating a 'bubble' around itself where the physics are different/more malleable, or simply resistant to the restrictions of conventional physics ("we don't go faster than light, we travel at a fairly sedate pace within the bubble. The bubble? Oh, yeah, that thing SHIFTS.")

And of course you avoid problems like time dilation, too. Close to light-speed travel brings up all kinds of problems in plotting nice stories. "I will hunt you down, even though it will take me 20 years to reach you! Er...and that's my sublight subjective time. It'll be 400 years for you. Ok, nevermind the hunt."
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Re: Science question.

Post by Phasmatis »

I did some research into artificial gravity for another project ages ago and the best solution was rotation, but there's a golden zone. The wheel or what ever that rotates needs to be slow enough as to not cause sickness, fast enough to produce the right about of gravity and big enough so there's very little or no difference in gravity between your feet and your head. With this project I have to say, you know what, it's the future and I have no idea how you would manipulate or direct gravity but I'm going down the artificial gravity route anyway because it's a shit load easier haha.

I looked into wormholes on the other project too and read up on macro wormholes that are formed in the quantum foam, I think it may be Stephen Hawking's theory, I can't quite remember. Linking quantum wormholes with my new project... If we somehow find two connecting wormholes that go to where we want, say near our sun to another system's star then make those wormholes bigger, we wouldn't need to travel millions of light years just to place another wormhole.

I don't like that fact that I have to go against physics but I can't see any other way. Especially as I would like to have situations where the player needs to turn gravity off or on to proceed.

I am now thinking about not having gravity at all now though. It would be different and perhaps more interesting that's for sure.
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