## Science-based what-if questions

For the discussion of the sciences. Physics problems, chemistry equations, biology weirdness, it all goes here.

Moderators: gmalivuk, Moderators General, Prelates

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

...So what type would work the best?

Eebster the Great
Posts: 2893
Joined: Mon Nov 10, 2008 12:58 am UTC

### Re: Science-based what-if questions

gmalivuk wrote:No, it doesn't make any difference. No amount of simple lenses can do what you want.

It's not that "no amount of lenses" can do it, because the Sun is certainly hot enough, it's that the total area of such lenses must be gigantic.

gmalivuk
GNU Terry Pratchett
Posts: 26036
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

### Re: Science-based what-if questions

How many lenses will get you a death beam?
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

Copper Bezel
Posts: 2416
Joined: Wed Oct 12, 2011 6:35 am UTC
Location: Web exclusive!

### Re: Science-based what-if questions

I don't understand andykhang's original question - the nanomachines are driving water droplets in the air around, and that's what's making up the lenses? But a death beam with a defined diameter is collimated.
So much depends upon a red wheel barrow (>= XXII) but it is not going to be installed.

she / her / her

Flumble
Yes Man
Posts: 1990
Joined: Sun Aug 05, 2012 9:35 pm UTC

### Re: Science-based what-if questions

gmalivuk wrote:How many lenses will get you a death beam?
fifty-twelve

At what point can a collection of focal points be considered a 'beam'? If we go for a 5cm spacing between all focal points, you only need some billions of lenses for a 70cm wide 'beam' from high in the sky down to the ground. And a multitude of that in water droplets.

Eebster the Great
Posts: 2893
Joined: Mon Nov 10, 2008 12:58 am UTC

### Re: Science-based what-if questions

More than a few it seems. But "billions" is not necessarily deal-breaking for nanobots. I feel like you might be underestimating the requirement a little.

KittenKaboodle
Posts: 135
Joined: Thu Dec 16, 2010 6:36 am UTC

### Re: Science-based what-if questions

gmalivuk wrote:No, it doesn't make any difference. No amount of simple lenses can do what you want.

While the OP perhaps did imply using the water droplets as lenses, since they have "absurd amount of [magical] nanomachines" I think we can do better than "simple" and while the word "beam" is problematic, they did say "converge" and I'm not so sure "beam" nesicarilly means it is collimated.

If (and don't forget we are using magic here) we use reflection rather than refraction an assuming we know the position of our target in three dimensions (allowing using a conical "beam"): http://web.mit.edu/2.009/www/experiments/deathray/10_ArchimedesResult.html and https://www.youtube.com/watch?v=bEvbj3O_yt8

edit: well, of course, refraction can work too: https://www.youtube.com/watch?v=i_8cynWnAw8 and a Fresnel is something one might be able to make with water drops (and magic)

morriswalters
Posts: 7073
Joined: Thu Jun 03, 2010 12:21 am UTC

### Re: 10 kg of antimatter

andykhang wrote:What happen if you put 10 kg of antimatter into the core of the earth:

1. Through a straight, vacuumed hole into the center?

2. Instantly through a 1 way portal?

And what would you do, personally, to destroy the earth with the above?
If we are dealing with magic then travel through your one way portal to the asteroid belt and get some rock moving towards earth. Like Ceres. If if space travel is too much take some to each super volcano on the ring of fire and try to set them off. You might get lucky. I like the nanobots. Make seven billion, give each a little antimatter and have them enter the bodies of all humans and use it to blow the aorta. No collateral damage to the planet.

p1t1o
Posts: 823
Joined: Wed Nov 10, 2010 4:32 pm UTC
Location: London, UK

### Re: 10 kg of antimatter

morriswalters wrote:
andykhang wrote:What happen if you put 10 kg of antimatter into the core of the earth:

1. Through a straight, vacuumed hole into the center?

2. Instantly through a 1 way portal?

And what would you do, personally, to destroy the earth with the above?
If we are dealing with magic then travel through your one way portal to the asteroid belt and get some rock moving towards earth. Like Ceres. If if space travel is too much take some to each super volcano on the ring of fire and try to set them off. You might get lucky. I like the nanobots. Make seven billion, give each a little antimatter and have them enter the bodies of all humans and use it to blow the aorta. No collateral damage to the planet.

Just for fun:

10kg / 7e9 = 1.43micrograms

Annihilate 2.86ug of matter+antimatter liberates = 2.57e8 J

1ton TNT equivalent = 4.184e9 J

Blow the aorta? Each person would have the equivalent of ~60kg of TNT allocated. No need to worry about specific bodyparts.

Soupspoon
You have done something you shouldn't. Or are about to.
Posts: 2963
Joined: Thu Jan 28, 2016 7:00 pm UTC
Location: 53-1

### Re: 10 kg of antimatter

p1t1o wrote:Blow the aorta? Each person would have the equivalent of ~60kg of TNT allocated. No need to worry about specific bodyparts.
Surely, though, if you were going to be indiscriminately killed off by a maniacal genius, you'd appreciate such a normally insignificant detail being arranged 'just so'... It shows that they do care. After a fashion.

p1t1o
Posts: 823
Joined: Wed Nov 10, 2010 4:32 pm UTC
Location: London, UK

### Re: 10 kg of antimatter

Soupspoon wrote:
p1t1o wrote:Blow the aorta? Each person would have the equivalent of ~60kg of TNT allocated. No need to worry about specific bodyparts.
Surely, though, if you were going to be indiscriminately killed off by a maniacal genius, you'd appreciate such a normally insignificant detail being arranged 'just so'... It shows that they do care. After a fashion.

Its true, I didnt take into account "wow" factor!

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Matter-Antimatter Anti-Structural Sniper Rifle

Suppose you have a sniper rifle with infinite durability (or something that could stand 100% mass-energy conversion,like here), it have a 1000 mm barrel and used a heavily modified 7.62×51mm NATO round, with the head and jacket made out of the same material of the rifle, and gunpowder capable of the method above, slotted in the middle is solid hydrogen. Suppose you shoot that thing, what will happen? I can only guess that the gas itself would create a nuclear reaction, but nothing else.

p1t1o
Posts: 823
Joined: Wed Nov 10, 2010 4:32 pm UTC
Location: London, UK

### Re: Matter-Antimatter Anti-Structural Sniper Rifle

Its unclear what you are trying to describe?

A sniper rifle that uses matter-antimatter annihilation to propel a solid hydrogen slug? Do you mean "metallic hydrogen under pressure"? Or just "some hydrogen"?

Or a solid hydrogen propellant for an antimatter-containing bullet?

"What would happen?" Well what do you think? Given that our barrel and bullet are assumed to be appropriately indestructible, you would get a very fast moving bullet with a nice and energetic warhead.

How fast? Well that depends on a lot of things.
How destructive? Well that depends on a lot of things.
"Nuclear reaction"? Again, its not clear exactly what you are describing, but if you want a hydrogen-filled bullet to fuse on impact, it will have to be going very, very fast indeed. Whether or not an antimatter powered "rifle" can do this for you is probably down to very sophisticated engineering since expanding gas is very very inefficient at moving things beyond a certain rate. You might end up with a slug only going a few times the speed of sound, just very very hot.

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

Sorry, I mean the bullet is like this: bullet head ->Solid Hydrogen (as padding, basically I want something that would expand as fast and as powerful as possible)-> propellant (Matter-Antimatter). Though if you said that it was inefficient, then what do you suggest? ( Personally I think this bullet need to act as a rocket itself (meaning to skip the solid hydrogen part), though that probably isn't as effective either, since matter-antimatter annihilation only release gamma ray as most)

p1t1o
Posts: 823
Joined: Wed Nov 10, 2010 4:32 pm UTC
Location: London, UK

### Re: Science-based what-if questions

andykhang wrote:Sorry, I mean the bullet is like this: bullet head ->Solid Hydrogen (as padding, basically I want something that would expand as fast and as powerful as possible)-> propellant (Matter-Antimatter). Though if you said that it was inefficient, then what do you suggest? ( Personally I think this bullet need to act as a rocket itself (meaning to skip the solid hydrogen part), though that probably isn't as effective either, since matter-antimatter annihilation only release gamma ray as most)

So you want a device that will shoot a projectile as fast as possible, and a projectile with the maximum amount of destructive force contained within it, is that about right?

Or are we talking a practical machine that could actually be used for anti materiel sniping?

You also need to do away with things like "Made from something indestructible" because if you have a material which is "indestructible" even in the context of being exposed to antimatter, or a significant antimatter annihilation event, then we can do a LOT of interesting stuff with that material, just nothing real.

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

The former,please. Piercing power isn't really a problem when this thing could annihilate most conventional structure on earth. (though I should have thought to used a 20mm for this)

Also it's for a novel I was thinking about, so it isn't need to be realistic (or even practical (it's a character thing), but it's recommended)

Edit: By the way, what is the interesting thing you're talking about? I see it could be used as a drill, but that it's

gmalivuk
GNU Terry Pratchett
Posts: 26036
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

### Re: Science-based what-if questions

For a portable rifle, recoil becomes an issue long before you get to velocities that require matter annihilation.
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

You could always fix that with a fixed bidet bolted on the ground with 100m long support pole drill deep into the ground. Or for my case, "magic".

doogly
Dr. The Juggernaut of Touching Himself
Posts: 5362
Joined: Mon Oct 23, 2006 2:31 am UTC
Location: Somerville, MA
Contact:

### Re: Science-based what-if questions

andykhang wrote: Or for my case, "magic".

This kinda attitude isn't gonna last you long in science club.
LE4dGOLEM: What's a Doug?
Noc: A larval Doogly. They grow the tail and stinger upon reaching adulthood.

Keep waggling your butt brows Brothers.
Or; Is that your eye butthairs?

commodorejohn
Posts: 1033
Joined: Thu Dec 10, 2009 6:21 pm UTC
Location: Placerville, CA
Contact:

### Re: Science-based what-if questions

...is there some alternate definition of "bidet" of which I'm not aware?
"'Legacy code' often differs from its suggested alternative by actually working and scaling."
- Bjarne Stroustrup
www.commodorejohn.com - in case you were wondering, which you probably weren't.

p1t1o
Posts: 823
Joined: Wed Nov 10, 2010 4:32 pm UTC
Location: London, UK

### Re: Science-based what-if questions

andykhang wrote:The former,please. Piercing power isn't really a problem when this thing could annihilate most conventional structure on earth. (though I should have thought to used a 20mm for this)

Also it's for a novel I was thinking about, so it isn't need to be realistic (or even practical (it's a character thing), but it's recommended)

Edit: By the way, what is the interesting thing you're talking about? I see it could be used as a drill, but that it's

Can you be more specific with practical requirements? - if the criteria are "as XYZ as possible", with no other constraints the concept could quickly become unrecognisable.

Do you have size/weight/capability requirements? Does it need to be man-portable? If it is a weapon, what is the intended target? What are the desired effects? Do you want to dig a hundred-foot crater or just punch through as much armor as possible? Do you have range requirements? Where will it be used?

For example, if you want to use it in-atmosphere, ramping up the speed of a kinetic projectile beyond a certain point will just increase how much energy is dumped into the atmosphere right in front of you, with negligible increase in energy on-target. But in space, muzzle velocity is almost unconstrained.

Then we can start thinking of some good ideas The difficulty of any design project with no upper bound on the design goals should be becoming apparent!

Oh, are there any story-based requirements - is the character required to "point" it at things? Threaten people with it? Does it need to last a long time or would a single-use/single shot thing be ok? Does it have to look a certain way? Does it matter if it is radioactive or otherwise detectable?

When fired, what are your requirements for the survival of anyone near your location? Is the user required to survive? Are local cities required to survive?
(Some of these are probably obvious, but the answers rule out or allow various concepts)

If you desire an explosive payload then antimatter would be the way to go, just handwave a very miniature variant of a penning trap, no indestructi-matter required.

***

The most powerful propulsion method I can concieve is to illuminate the base of your projectile with very (VERY) intense radiation, the sort of intensity you get if you were pressing your eyeball up against a nuke on detonation. An ablative layer on the projectile would very (VERY) rapidly vaporise, giving very high thrusts. Radiation pressure itself would add further significant thrust. This way, forces many orders of magnitude greater than gas pressure alone can be generated, and with sufficient energy (and dependant on projectile properties), significant fractions of the speed of light can be attained.

The science of this is very real and related to the mechanisms of compression utilised in real-life nuclear weapons.

Whether or not this is suitable for your requirements Im not sure, it may require some indestructi-matter to enable your user to survive using it, or if you want the weapon itself to survive being used.

***

You can only think of a drill to utilise indestructi-matter?
Ok, so lets drill a hole right through the earth, line it with the same matter and use it for transport. Or how about a submarine for going into the sun? A tank that can survive a direct multi-megaton nuclear strike? Or howabout a normal room lamp, but the lightbulb is a multi-megaton nuclear weapon in a little box- if we can let a little visible light leak out
You could even use it to manufacture very compact nuclear weapons as you could use its infinite physical strength to vastly enhance compression.
Heck, you could just use it to make flasks to contain large quantities of antimatter and slosh it out onto anything you want to destroy...
You could make wafer-thin skyscrapers and bridges almost too thin to see, space elevators become trivial.
You could make vacuum dirigibles, ringworlds, rimworlds, dyson spheres, generation ships, ships the size of planets - you could try your hand at stellar engineering and build a Shkadov thruster or convert the Earth into Globus Cassus!

I think I could go on for some time! What a fun excersize!

***

Im not sure, but that might be the most question marks I have ever used in one comment XD

***
gmalivuk wrote:For a portable rifle, recoil becomes an issue long before you get to velocities that require matter annihilation.

Unless you construct a "recoilless" design, with equal forces in either direction. Projectile goes forwards, diffuse blast goes backwards, zero recoil.

Not the only problem of course.

Soupspoon
You have done something you shouldn't. Or are about to.
Posts: 2963
Joined: Thu Jan 28, 2016 7:00 pm UTC
Location: 53-1

### Re: Science-based what-if questions

commodorejohn wrote:...is there some alternate definition of "bidet" of which I'm not aware?

The "bathroom" bidet is named after the French for a small pony, assumedly which one might sit astride with feet on/barely off the ground. I learnt that just the other day, coincidentally.

I suspect that a tripod(tetrapod?)-like bolting platform might also be considered a pony-equivalent load-bearer enough to have gained the same name, but I'm not actually aware of this perhaps rather specialised term in the field of ballistic weapon mountings.

Or just find an actual bathroom bidet, bolted to some convenient bit of floor (the discreet bathroom window perhaps being a useful look-over onto a wide but mostly distant range of urban environment, in your chosen field of fire, without attracting too much obvious attention1 from counter-snipers, and reinforce this with the 100m drilling pole (however you get that into the WC!). But I suspect the pole, alone, will suffice (if it does help at all!), so the logical conclusion is that it's disinformation, intended to draw the counter-sniper beads onto all frosted glass windows and air-vents in the buildings, leaving you free to emplace your supersniper-rifle in some other location (a bay window, with vertical blinds closed, and firmly anchored against unexplainable/unforgivable draughts that might catch your opponents' eyes?), set it up with the necessary remote firing system then get out of there before the annihilative percussion mechansim is used, to irradiate the room and perhaps kill any operator even quicker than the retaliatory fire back-tracks there itself.

1 At least until you fire... The various effects in the vicinity of the weapon and along and around the projectile trajectory will probably be unmaskable, maybe fuzzable at best.

gmalivuk
GNU Terry Pratchett
Posts: 26036
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

### Re: Science-based what-if questions

p1t1o wrote:
gmalivuk wrote:For a portable rifle, recoil becomes an issue long before you get to velocities that require matter annihilation.
Unless you construct a "recoilless" design, with equal forces in either direction. Projectile goes forwards, diffuse blast goes backwards, zero recoil.
Yeah, more generally I meant the problems that arise from however Newton's Third gets dealt with. If you're putting out a diffuse blast right next to the shooter, there's still in principle a limit to how big that blast can be.

Soupspoon wrote:I suspect that a tripod(tetrapod?)-like bolting platform might also be considered a pony-equivalent load-bearer enough to have gained the same name, but I'm not actually aware of this perhaps rather specialised term in the field of ballistic weapon mountings.
As far as I can tell, it doesn't have that specialized meaning in English, but it might in andykhang's native language.
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

p1t1o, I like your idea .

Requirement:

Size/Weight/Capability: aside from the 1000mm,with 20mm bullet and have a cadtridge, not much else.
Man-portable: Yes, though if that the case, maybe the weight should be adjusted...or add anti-gravity cus why not?
Intended target: Mass army and/or stronghold. Being able to change the terrain with just a single shot (Though a nuke would be better for that, but romance)
Desired effect:Hm... maybe as if leave the trail, the trail itself undergone heat explosion. And yeah, 100-foot crater it is (though it could be multi-purpose, but that just require to change the bullet)
Range requirement:...With this kind of weapon, it's comparable to an ICBM in range already, so how about that (though that mean you must adjusted for the curvature of the earth, or how for the bullet to go through the mantle and hit any spot on earth, which need different requirement, so marked as "potential")...Maybe should have added to adjusted the range as will, but that could be solve by bullet.
Location: Prefertively to still be able to used as "significant speed of light" in-atmosphere, though testing the speed in space sound good...

Story: Yes it need to be able to pointed as thing, last a long time. Prefertively me and anyone within a 2m radius to survive (though that could be solve by "writting", so it could be ignore). Any look is okay. And not really (since everyone who saw it is death )

p1t1o
Posts: 823
Joined: Wed Nov 10, 2010 4:32 pm UTC
Location: London, UK

### Re: Science-based what-if questions

andykhang wrote:p1t1o, I like your idea .

Now we’re talking, you don’t need anything near indestructimatter for these requirements.

First up, we want to put a decent sized explosion into a 20mm round, enough to create a 100foot crater, very roughly put. This should fulfil the criteria of 1-shot bunker demolition, terrain changing and a plausible threat to a “mass army”.
Using 1960’s technology we can already put a20kiloton nuke into a 155mm arty shell. There are plausible designs for an antimatter-catalysed thermos-nuke. So into our little 20mm shell we’d have a lithium deuteride secondary and a tiny speck of antimatter in the nose (properly constrained of course, see: penning trap).

You could keep it a straight antimatter warhead, though in my opinion, that makes it less interesting. But it does allow fuel sharing (see below).

With antimatter, you are looking at about 80kilotons of yield (roughly 4x Hiroshima) for 1 gram AM annihilating with 1gram matter. There are complicated particle physics reasons why it wouldn’t be quite so much, could be as low as half that, but its still pretty potent. You should be able to get several grams into your device but don’t forget the containment mechanism! And that you need some AM for propulsion.

So we have a nice little 20mm package to get to target.

Wow, these requirements are a little stronger (Im reading down as I go). Basically global range, with the option of firing through the Earth.
I would put the “through the Earth” requirement to the side for now, unless it is absolutely essential to the narrative. This capability far outweighs the destructive potential you desire, and would probably require some VERY exotic physics (or more likely, completely made-up physics, like teleportation).

You definitely don’t want the projectile to reach relativistic speeds in-atmosphere as this would liberate considerable energy right in front of your face. But you could have an “in-atmos” safety catch and a “vacuum – unrestricted” switch for when it is useful.

These speed and range requirements should be taken care of by putting a wee bit more antimatter in the rear of the projectile for propulsion, and a tiny AI for guidance. Im not sure how much AM you’d need to get the round up to a decent fraction of lightspeed, but it should be ballpark enough for your use. You can even share the “warhead” and “fuel” AM capacity so that you can sacrifice yield for more speed/range.
Note that this weapon will not require a “barrel”, range/speed requirements mean that gas propulsion is of negligible use.

It might resemble more of a miniature-drone “dispenser” that “releases” rounds to find their own way to the target. The “knife drones” from Iain Banks’ “Culture” novels are similar in concept they are usually used for covert assassination or self-defence, though a high-yield capability is never really ruled out.

I dunno if you watch “The Expanse” but there is a neat scene in a season 2 episode where a Martian Marine is shown to have a similar weapon mounted on her back (minus the nuclear warhead and relativistic capability), check it out.

So, a first draft: a backpack or briefcase. A large slot spits out something that resembles a 20th century 20mm round. A very miniature set of reaction-control thrusters powered by minute amounts of on-board antimatter allow it to move through the air at will (with antigrav being a slightly less plausible option). It could loiter around you, or it could depart immediately. It could even be told to loiter somewhere else, take a roundabout route to target, or anything else its limited but smart AI can think of.

On activation, its main AM drive fires. In-atmos, it is very limited but still capable of high-hypersonic flight (think London-to-Sydney in an hour or two), though long-range planetary shots could be made sub-orbital and thus you can open up the throttle a bit in space. So it can strike anywhere on the globe within, say, an hour? That’s not bad, the atmosphere gets in the way a lot, not much to be done about that unless you want to invoke teleportation - which is a bit of a boring solution in my opinion (not to mention a little outside-of-science)

The round is going to give off significant radiation, mainly gamma, when it uses its drive (and of course on detonation). You could make it so the main exhaust is highly collimated - ie: as long as you are not directly behind it, you are fine, but the round should take care not to irradiate anything (like bystanders) too badly by accident - and the lower dosage given off by the positioning thrusters can be said to be below the threshold of your futurey medical science. The exhaust will also be very, very hot and bright, across the whole EM spectrum unless operating at a very, very low setting. The slower it goes, the "quieter" it will be.

Atmospheric speed will be limited by the heat tolerance of the round itself (temperatures above several thousand degrees kelvin can easily be reached at only a handful of Mach, see: atmospheric re-entry) and the signature that you want the round to leave in its wake, don’t forget the beam of radiation which is the exhaust.
The drive itself is like a barely constrained version of the warhead – potentially very destructive, so the round’s AI would have to take pains not to accelerate too fast whilst still near you (or any bystanders) or point it’s a\$\$ in your direction until at a safe(ish) distance.

Essentially, its as if you would be carrying a magazine on you loaded with an array of tiny, high powered, kamikaze spaceships, with all of the tactical flexibility that that offers.
You couldn’t “point” it, like a handgun, at someone, but you could easily have a round on hover-standby approach someone very closely, with its sharp tippy-tip, the radioactive tickle it gives off and rather delicious payload, it should suffice for intimidation purposes, if that was what you wanted.

Did I miss anything? It cant be fired through the Earth, but it hardly needs to be. The design relies heavily on a high degree of miniaturisation (relative to 21st century Earth tech) but it should be scientifically plausible.

***
From "The Expanse", see the slot on the left side of the backpack? Pretty much spot-on, only ours is a couple orders of magnitude more capable, thats the antimatter advantageTM

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

Hm...I could let the briefcase to transform into something "sniper rifle" like, with it acting like a guidance lauchpad by way of electromagnetic transportation (or railgun), save a bit of fuel and stuff. As for the "Through the earth" stuff, I will let it be the job of AM orbital bombarment. Other than that, good enough for now. This thing is probably the best I think of, aside from warp cannon.

As for the speed, I guess the rocket equation should be good enough. Not sure about the effective exhaust velocity of such a drive though.

Edit: Also you could used something like lead to increase the yield while saving some space too!

p1t1o
Posts: 823
Joined: Wed Nov 10, 2010 4:32 pm UTC
Location: London, UK

### Re: Science-based what-if questions

andykhang wrote:Hm...I could let the briefcase to transform into something "sniper rifle" like, with it acting like a guidance lauchpad by way of electromagnetic transportation (or railgun), save a bit of fuel and stuff. As for the "Through the earth" stuff, I will let it be the job of AM orbital bombarment. Other than that, good enough for now. This thing is probably the best I think of, aside from warp cannon.

As for the speed, I guess the rocket equation should be good enough. Not sure about the effective exhaust velocity of such a drive though.

No reason the deployment mechanism cant be rifle-shaped and give it a nice push, the dangerous exhaust is a good excuse for this.

Im a fan of coilguns for my electromagnetic launches

http://www.projectrho.com/public_html/rocket/

Depending on the particular design and mechanism, an AM engine can have exhaust velocities anywhere from several tens of km/s all the way up to large fractions of the speed of light, though this says nothing about the thrust level.

If half the mass of the projectile is AM, and with a middling (for antimatter) exhaust velocity, you can easily see delta-V's in the thousands of km/s.

In fact, unless I am very much mistaken, if half your mass is propellant, then dV = exhaust velocity.

**edit**
Dont take my word on that last sentence, Im not sure. Should be ok for ballpark figures.

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

Oh yeah, worked as a "funtional" and completely intentional nuclear flamethrower, if you're brave enough. And the ratio should be e/1 if you want dv= exhaust velocity.

Edit: also I did a ballpark estimate too: If for an instance the exhaust velocity is about 10% of the speed of light, you could get the bullet to that speed with a 3/1 ratio (or 2g of proppelant for 1g of projectile) (of course, realistically you only get about 1% or so as most, in vacuum)

Edit 2:...Unless you get a beam core or a plasma core. Which mean that you need a coil gun-like mechanism to "guided" the charge pions from the bullet (since railgun can't do that). So this thing need to act more like a booster (a very,very,very powerful booster).

Edit 3:...And that with real science. If you somehow could achieve 100% conversion... Yeah, you probably still need some indestructium after all.

Edit 4: By the way, I would probably named the nuclear flamethrower Laevatein mode, and sniper the Gungnir mode

Sableagle
Ormurinn's Alt
Posts: 1437
Joined: Sat Jun 13, 2015 4:26 pm UTC
Location: The wrong side of the mirror
Contact:

### Re: Science-based what-if questions

p1t1o wrote:
andykhang wrote:By the way, what is the interesting thing you're talking about? I see it could be used as a drill, but that it's
Ok, so lets drill a hole right through the earth, line it with the same matter and use it for transport. Or how about a submarine for going into the sun? A tank that can survive a direct multi-megaton nuclear strike? Or howabout a normal room lamp, but the lightbulb is a multi-megaton nuclear weapon in a little box- if we can let a little visible light leak out
You could even use it to manufacture very compact nuclear weapons as you could use its infinite physical strength to vastly enhance compression.
Heck, you could just use it to make flasks to contain large quantities of antimatter and slosh it out onto anything you want to destroy...
You could make wafer-thin skyscrapers and bridges almost too thin to see, space elevators become trivial.
You could make vacuum dirigibles, ringworlds, rimworlds, dyson spheres, generation ships, ships the size of planets - you could try your hand at stellar engineering and build a Shkadov thruster or convert the Earth into Globus Cassus!
Assuming you can get fancy enough to build a rifle out of this vibranium-adamantium stuff, you should have no trouble building really good kitchen knives, coping saws, cross-grain saws, long-grain saws, chainsaws with truly smooth runners and gears and bars and blades only 0.1mm thick so they take far less power to operate, really efficient, really lightweight bicycles that never rust or bend and will float if you ride into a canal, body armour with very low weight and plenty of flexibility up to a limit that conveniently matches the wearer's natural flexibility, vacuum airships, minefield clearing equipment that never gets blown up, lighter and more efficient trains and trams, feathery bridges that'd make Rivendell look clunky, super-light airliners with much-improved safety (including zero risk of a ruptured fuel tank incident), ... and if you could control this material's optical and properties, really awesome thermos flasks.
Oh, Willie McBride, it was all done in vain.

gmalivuk
GNU Terry Pratchett
Posts: 26036
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

### Re: Science-based what-if questions

p1t1o wrote:From "The Expanse", see the slot on the left side of the backpack? Pretty much spot-on, only ours is a couple orders of magnitude more capable, thats the antimatter advantageTM

I dunno, I think even if you had this antimatter weapon, Bobbi Draper could still wreck your shit if she needed to.
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

gmalivuk wrote:
p1t1o wrote:From "The Expanse", see the slot on the left side of the backpack? Pretty much spot-on, only ours is a couple orders of magnitude more capable, thats the antimatter advantageTM

I dunno, I think even if you had this antimatter weapon, Bobbi Draper could still wreck your shit if she needed to.

Not if it explode in her face, though that miiiight be a bit of a pyrrhic victory

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

So...now that the gun is done, how do we figure out the way to defend against a AM drive bullet coming your way. I suggest using that inderstrutium, but do you guy have others idea?

Soupspoon
You have done something you shouldn't. Or are about to.
Posts: 2963
Joined: Thu Jan 28, 2016 7:00 pm UTC
Location: 53-1

### Re: Science-based what-if questions

Be somewhere else!

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

But what if it is aimed at you? Especially for this type of bullet, jamming won't work, either because the circuitry inside it is tough enough to withstand such force, or it have been long fried, or too late to do anything when it reach that speed. A shield is good, but you need the same type of material that make up the gun to make the shield, and you need to deal with the force it is carried too, so sometime the best way is to literally firing the same thing as it like some active defense system installed on battleship. And any other method would require some illegal science. (like the klein's bottle field, that need some convienience way to bend space)

p1t1o
Posts: 823
Joined: Wed Nov 10, 2010 4:32 pm UTC
Location: London, UK

### Re: Science-based what-if questions

andykhang wrote:So...now that the gun is done, how do we figure out the way to defend against a AM drive bullet coming your way. I suggest using that inderstrutium, but do you guy have others idea?

Well theres always decoys or electronic jamming to try and spoof your weapons guidance, but if you want a hard-kill the obvious answer is use another copy of the weapon itself. We're not talking very high fractions of lightspeed so you can still see it coming if your sensor coverage is good enough - the rounds have quite high EM signitures.

The only caveat is you have to stop it whilst still outside the blast radius. If in space, there may also be the matter of AM continuing along the weapons trajectory and reaching you anyway, though that would not be as bad as a direct hit.

"Armor" isnt really a useful concept with weapons of this magnitude, either the target is vulnerable or it isnt (perhaps it is protected by a mile or so of rock, I wouldnt exactly call that "armor")

**edit**
Oh looks like you already thought of most of that. I wouldnt rule out jamming though, it doesnt matter how "hardened" your circuitry is, you can still mess with its sensors.

The defence question is similar one to what militaries face today. For example in anti-ship warfare - how do you defend against an impossibly fast weapon that you can only detect with a minute or so notice and you can only move at 20 knots or so. Electronics, decoys and hard-kills at a long a range as possible. Fighter jets do it slightly differntly as they have the ability to manouvre and their signitures are far less, so jamming/decoys are more effective, but close-in weapon defence is less possible with sucha small platform.

Defence (and attack for that matter) will always be a trade-off of many factors, ie: jamming alone might not work, but it might make the incoming weapon more susceptible to a decoy, which might give you more time to engage with a close-in weapon system.

Of possible relevance - there is a new technique called "Jaff" or "Jammed Chaff" whereupon an aircraft will deploy chaff decoys, and aim electronic jamming at the chaff. The weapon now percieves a jamming effort coming not from the target but from elsewhere. This counters the "home-on-jam" capability that some modern weapons have to defeat classic jamming.

So there are alot of potential ways to defeat your weapon, some techniques very old even. But this is why we gave it an antimatter engine and a smart AI, to give it the best chance against the best targets. It remains of course, very deadly.
Last edited by p1t1o on Thu Mar 09, 2017 4:43 pm UTC, edited 1 time in total.

p1t1o
Posts: 823
Joined: Wed Nov 10, 2010 4:32 pm UTC
Location: London, UK

### Re: Science-based what-if questions

gmalivuk wrote:
p1t1o wrote:From "The Expanse", see the slot on the left side of the backpack? Pretty much spot-on, only ours is a couple orders of magnitude more capable, thats the antimatter advantageTM

I dunno, I think even if you had this antimatter weapon, Bobbi Draper could still wreck your shit if she needed to.

Yes I think I'd very much prefer using this weapon whilst being on her side.

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

But then that mean we get a strongest spear without even a suitable shield. Even if we wired the rifle itself with many security, it disturbingly simple mechanic (relatively) behind it would mean that someone, somewhere would build crude, but remain very deathly similar weapon and pointed it at us if they even get a whiff of the tech. Though lower level of tech mean that what you said could work.

Now for a design: Probably the same as the weapon, but it instead fired short-range (though "short" still mean 2-3 digits kilometer away), but rapid and in burst to hard-kill this as much as possible. The bullet itself also have to have great acceleration, along with many jamming and disturb tech as possible (such as chaff (though any chaff that could survive hypersonic speed is still enough to knock down a plane), smoke, short-range EMP or somehow drastically slow the speed (by briefly increase the density of the air or smear it with friction-gaining subtance) to trick it have undergone lithobreaking and explode). Probably triple the firing rate of a gatling gun for it to work, and an accurate enough wide-field detection and guidance system to coordinate the bullet hell it give out.

p1t1o
Posts: 823
Joined: Wed Nov 10, 2010 4:32 pm UTC
Location: London, UK

### Re: Science-based what-if questions

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Re: Science-based what-if questions

Hm...that work itself perfectly actually. The carrier itself could be launched by a railgun, and you just need to tweet it a little for it to fire AM drive... the size is a bit of a problem though, since this thing obvious design to knock rocket out of the sky, but it actually work well if you incoporate some drive that need a bit more size.

andykhang
Posts: 192
Joined: Mon Sep 05, 2016 4:40 pm UTC

### Pierce through the Sun

Now that I'm mostly done with my previous question, let go with this one: Suppose I create something (a weapon, spaceship,etc...) that could be used to pierce through the Sun right in the center. What is the requirement, and what would happen as this is passing through it?