1. Feb 2, 2014

javascripter

So I was reading some books with implosion grenades in them, and was wondering if they were theoretically possible.
Here are a few things I came up with from research and my own brain, the ones from my own brain may be garbage, and if so please let me know.

So apparently a light bulb is basically a weak implosion grenade. Problem is, you need a massive object to create a small implosion using this.

I don't know anything at all about quantum teleportation, but would it be possible to cause everything within a small radius to teleport a ways away and therefor create a temporary vacuum? Or even just all gas? (if the teleporter is required to be larger than the materiel being teleported, or things have to be controlled this obviously won't work, but if you could teleport a sheet or a polygon.)
Another idea I had was create a black hole, problem here is first you need it to decay immediately, I don't know how fast hawking radiation would cause a smallish black hole to decay, but I'm somewhat certain if it pulls things in it won't decay fast enough to stop it from growing massive and killing everything. And if we have this technology send a drone with the biggest black hole generator you can.
Final idea: Somehow convert all matter in the area to energy, this would also have the advantage as a weapon of causing other damage, but would that have to end up as basically a nuclear grenade that wouldn't actually work because most matter is to stable?

I'm probably over-thinking it, but I was curious if implosion grenades were theoretically possible, and if my brains processes are worth anything or garbage?

2. Feb 2, 2014

Simon Bridge

You need to start out by thinking what you mean by "implosion grenade" ... technically anything that dramatically reduces the pressure in a volume produces an implosion. For example, drop a match into an empty can and seal the opening and watch it implode.

1. teleportation: physical translocation of matter without passing through the intervening space?
Does not happen. But if it did then you could teleport the air from some volume and that would create the needed low pressure.

2. black holes: quantum black holes could decay almost instantly - the trouble is that a black hole is only as strong as it's mass ... small black holes have no more gravity that the mass they replace. OTOH: some methof to dramatically collapse matter in the target volume would also leave a sudden low pressure (the volume has suddenly reduced) ... so you get an implosion effect.

3. total conversion of matter - would result in an explosion.

I don't know where you get the idea that a light bulb is an implosion device.

3. Feb 2, 2014

Enigman

Breaking a container of rarefied gas or total vacuum should decrease the pressure causing an implosion of sorts, shouldn't it?

4. Feb 2, 2014

Simon Bridge

Oh I see ... sure: evacuate a container and arrange for it to break.
Well done.

5. Feb 2, 2014

javascripter

That is what I figured. (Especially on the third one. Unless through some magic you could convert it to light, in which case you are the <Tesla/Da Vinci/Archimedes> of this age. Would that work if we figured a way out to do that?) Forgot criteria for it to count as a grenade.
So here it is:
1) Able to be thrown by a human. This could rule out black holes for being to heavy.
2) Not a suicide grenade. This could also rule out black holes, but if you have this it is just a bomb, send a drone.
3) Causes enough damage to make sense to throw. This is why lightbulb doesn't count.

Another idea dependent on the matter in the air: If for example (I actually have no idea on the accuracy of this, but it is an example) O3 (ozone) takes up less space than O2 (oxygen) could you set something up to rapidly convert O2 to O3?

6. Feb 2, 2014

Enigman

Don't need no woo woo, antimatter will do. BUT converting even a measly 145g of matter (mass of a parrot) into light will give enough energy to do this:

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

I am thinking a vacuum bubble. A small orb of handwavium which would rapidly expand and then burst off causing an implosion.
Requires too much energy I would think, an explosive grenade would do more damage with the same energy.

7. Feb 2, 2014

javascripter

Oh, that is slightly humorous, I said Archimedes and then forgot about his mirror towers. (That show that light can cause damage.(realized that sentance was horrible communication, but hopefully you get what I meant by "cause damage".))
I didn't think about it, but I guess if you had dense antimatter you could cause an implosion, not sure if it would be throwable though.
It looks like 1 mole of hydrogen is about 1 gram, according to Google. It also looks like a frag grenade can weigh 15 ounces, or 396.893 grams according to Google. So you could fit almost 400 moles of hydrogen, if you had a strong enough shell that could break.
According to wikianswers air at sea level has about 1.2 kg per cubic meter, which is 1200 grams per cubic meter.
So you could get rid of a third of a cubic meter with a 400 gram grenade? Not sure how much of an implosion that would cause, but the volume of a 5.15 cubic inches for a light bulb, according to a youtube video I found (Didn't watch the whole thing.) which is 8.43934e-5 cubic meters (copy/pasted from google calculator) you would have a much larger volume than that, but I don't know if it would cause any damage, and if it would, would it make sense to make that with antimatter?

8. Feb 2, 2014

Enigman

400gm gives 3.595 x 1016 J
Fat Man had a payload of 8.8 x 1013J (nuke at Nagasaki)
Little boy had a payload of 6.3 x 1013J (nuke at Hiroshima)
Your 'implosion' grenade would then cause an explosion with payload of [strike]238 times[/strike] 476 times(forgot to account for the matter annihilated) of Hiroshima and Nagasaki COMBINED.

Last edited: Feb 2, 2014
9. Feb 2, 2014

cjl

Or in other words, about half as big as this explosion:

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

10. Feb 2, 2014

javascripter

Ah, ok. I didn't know much about antimatter other then it went away when combined with normal matter, so ya, antimatter doesn't sound like it makes implosions.
I hereby come to the conclusion that with our current understanding of physics logical implosion grenades are impossible.

The Thing about an expanding material seems interesting, but I have no idea how that would work, if there is a way that a hollow object to expand by several factors of itself and then burst or something.

However, I can say that an antimatter grenade sounds somewhat dangerous. And my knowledge has been expanded, so that is good.

11. Feb 2, 2014

SteamKing

Staff Emeritus
Old-style televisions with CRTs made much bigger implosions than a typical light bulb, but they weren't dangerous unless you got cut on some glass.

I think the reason you don't see any implosion grenades is that the implosion is necessarily limited in scope. An exploding device, even one as small as a hand grenade, is capable of much more destruction.

A typical nuclear detonation is much more destructive in the atmosphere because the release of nuclear energy causes a sudden heating of the surrounding air. It is the expansion of this air which wipes away what remains after the heat from the fireball has done its work. A nuclear detonation in outer space, while spectacular, would not be nearly as destructive as one in atmosphere, excepting things like EMP of course. I believe there was a discussion recently of whether a nuclear detonation on the moon would even be visible on the earth if one were not already looking for it.

12. Feb 2, 2014

Simon Bridge

... the light is the exploding part. Sure you have a sudden absence of matter but the outwardly exploding light exerts it's own pressure. After the explosion you'd get an inrush ... just like with any high explosive where the reaction products are more dense than the reactants. It's just that the outrushing light will do far more damage over a larger volume than the wee pop from the implosion.

Black holes don't have to be very massive (SF here) - but wouldn't make an implosion happen anyway. At least not due to it's gravity.
... see the same author on the Star Trek reboot: how a black hole really destroys a planet from inside.

So how a BH grenade would go:
Your SF terrorist/freedom-fighter throws a small handlheld object that, after a delay, suddenly collapses into a black hole ... that would make a pop as the surrounding air rushes into the gap - maybe get a gamma ray burst when the inrushing air gets too close to the center.

Grenades, like you describe, are just bombs with a short timer.
Otherwise: same notes as before.

And the black hole too. The effect is just too small.
(Leaving aside other reasons it may make sense to throw a lightbulb at someone...)
Mind you, if you had teleporters there is always teleporting a planet at your target - the grenade, then, is basically a remote control/homing device and machines do the actual "throwing".

Or get your special ops team to illuminate the target, then the orbital teleportation beams transport the target to the bottom of the sea. Use "castling" style teleportation and the drug-cartel stronghold just turned into a spherical bowl of seawater.

Maybe - but you can convert O2 to CO2 very fast and that can make an implosion too - the match in a can example ... just heating air a lot makes it rush upwards sucking more air inwards too.

Putting a shell of explosives around something makes the something implode - it's how atom bombs are set off and has been proposed as a safety-gimmick for oil wells. Presumably it could be used as a precise way to manage demolitions: put a collar of charge around key supports... the destruction goes just where you want. I think it is more likely to use other kinds of shaped charges though. As the others point out - you get more wanton destruction more easily from explosions.

There is a SF staple with giving people explosive collars ... from this discussion you can see the explosives don't have to be all that powerful. Imagine a home-detention scheme where the collar around your ankle severs your foot if you step outside the safe zone?

It can also be used as a way to study how materials behave under extreme stresses.

You realize there are applications to the idea that do not involve destroying things or killing people right?

13. Feb 3, 2014

Enigman

Er, no. A burning match(cellulose) just adds $H_2O$vapours and $CO_2$ in the system along with heat.
At the end you have more moles of gas than before, BUT the heat in the system means the gases have expanded which after cooling down (and sealing the opening) causes the implosion.

14. Feb 3, 2014

Enigman

Castle Bravo was 6.3 x 1016 (wolframalpha figure).
A 400g of antimatter means 800g annihilated which is 7.19x1016
And that's 1.14 times of Castle Bravo.

15. Feb 3, 2014

Simon Bridge

Hmm... I gave an incomplete, possibly misleading, description of the process.

I thought it would still work, though, if the match was struck in the sealed container: since the water condenses on the walls. Or is that what you mean?

There's probably a better example of a chemical reaction whose products have much higher density than the reactants.

16. Feb 3, 2014

Enigman

It doesn't matter if the water condenses (though it would take a longish time to condensate), the number of atoms of CO2 is still equal to O2.
Assuming there is no significant change in number of moles and volume is constant (well, just at the beginning of the implosion)
$\huge{\frac{P_1}{T_1}=\frac{P_2}{T_2}}$ (Gay-Lussac's law... I think)

Here P_1 the initial pressure is equal to atmospheric pressure

As $T_1>T_2$

$T_1/T_2>1$

$P_2/P_1<1$

$P_2<P_1$

$\large{\it{\mathcal{*\!S\!M\!A\!S\!H\!*}}}$

Last edited: Feb 3, 2014
17. Feb 3, 2014

cjl

I was using your figure of 3.5*1016J, since I figured it had been amended when you amended the other figure (I didn't run the calculation myself). That explains the discrepancy...

18. Feb 4, 2014

Beowulf2

I would recommend Steven Donaldson's Gap Series aka The Gap Cycle see here: http://en.wikipedia.org/wiki/The_Gap_Cycle loosely based on Wagners opera The Ring Cycle, or Der Ring des Nibelungen in the original German, for viable ideas about implosion grenades; whilst the physics in The Gap Series refers to singularity grenades it is much of a muchness. And for someone who is not a Scientist I think he does a pretty good job of explaining how singularity grenades might work, if of course they could.

Of course in the actual books they are far from being able to be thrown, in fact they are so dense that only a superhuman could carry one, and even then it would require an almost impossible strength, none the less though this technology is deployed by something more than human, and in a way that explains how it could be. That said it's called fiction for a very good reason. Thor can indeed wield Mjolnir (look it up, it's Thor's hammer) because of his inhuman strength the point in the book though is should he cast such a heavy hammer at any human let alone gods let alone should one such as Thor be allowed to wield such power even to defend the gods inevitable demise in the Twilight of the Gods..

Meh end of the day I recommend it as damned finely told fantasy/Sci Fi, it certainly is perhaps one of the best series I ever read, perhaps up there with The Lord of the Rings Trilogy et al. But then to make a very weak joke "I AM BEOWULF!"

Last edited: Feb 4, 2014
19. Feb 5, 2014

Simon Bridge

This is sort-of an aside - maybe we need a separate thread?
But isn't CO_2 denser than O_2 (at the same temperature) - i.e. you'd need a higher temperature to get the same pressure?

Also - isn't condensed water is denser than water vapor? So when the vapor condenses out you get a pressure drop?

I understood the vapor condenses almost right away on the cooler sides of the metal container.
Mind you - needs help on a hot day.

Another approach to the demo is to boil water inside a can, remove the heat, seal the can, put it in a cold place. eg.
http://www.nsta.org/publications/news/story.aspx?id=51859

I've seen it demonstrated by just dropping a match in ... but have not found an online example.

20. Feb 5, 2014

Enigman

Yes, $CO_2$ and $O_2$ are not ideal gasses but as the pressure and temperature are in the normal range the approximation holds.
Compressibility factor $Z_{CO_2}$=0.9949838625 $Z_{O_2}$=0.9989935 which are almost equal to 1.
http://www.peacesoftware.de/einigewerte/calc_co2.php5

Yes, its denser but I don't think the volume of water vapour is so much that it can't be safely neglected. Anyway dew point temperature is 20 °C (dry bulb temp at 1 bar) and the trick works at much greater temps (I did it in about 27°C).