# Are hand-held high energy weapons possible via known physics? **URL:** \ **Category:** Factual Questions\ **Created:** [August 30, 2013, 2:37am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557 "2013-08-30T02:37:55Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Habeed](https://avatars.discourse-cdn.com/v4/letter/h/a587f6/32.png) [@Habeed](https://boards.straightdope.com/u/Habeed)\ **Post date:** [August 30, 2013, 2:37am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/1 "2013-08-30T02:37:55Z")
The reason this is in general questions and not IMHO is it is a factual question based on current accepted knowledge. Conditions : You have the technology to arrange matter in any arbitrary configuration that is stable. Could you build a “hand held” energy source in a weapon that produced, say, 100 kilowatts of continuous electric power, and could fire until the waste heat made it too hot to handle? By “hand held”, it has to be smaller than about 20cmx20cmx20cm, and weigh less than 10 kilograms. Also, it can’t emit fatal (to a human today) amounts of gamma rays. Chemical energy sources won’t do it, and the problem with all the nuclear reactions I know about is that 1. To create a chain reaction, you need a critical mass. That means several kilograms of high purity fissionable material at a minimum, and the real problem is that the neutrons released by a chain reaction can’t be stopped by anything other than a lot of material, far more than 10 kg worth. 2. Nuclear batteries that don’t involve chain reactions can’t be throttled. Short half life Americium that emited beta particles might work, but there would be know way to turn it off. Am I missing anything? I’ve read about a theoretical nanoscale battery that stored energy in electron spin and if you could build trillions of complex molecular subunits to make such a battery, it would be practical. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [August 30, 2013, 2:39am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/2 "2013-08-30T02:39:54Z")
Kinetic energy weapons are quite common. 😉😃 ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 30, 2013, 2:44am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/3 "2013-08-30T02:44:16Z")
Critical mass isn’t (in principle) a problem, either. The critical mass of uranium or plutonium is several kilograms at low pressure, but you can decrease that either by compressing it, or by using a different isotope. With a more active isotope like americium, you can get a critical mass from a few grams. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [August 30, 2013, 2:58am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/4 "2013-08-30T02:58:34Z")
To cheat just a little, you could have “beamed power.” The real power supply is in a big building in Omaha, but it gets beamed to your hand-weapon, which then uses it to produce a zap ray. Otherwise…matter/antimatter power cells. That’s pretty much the upper limit on energy storage. Twelve ounces of matter, twelve ounces of antimatter, unite the two judiciously, and you’ve got a blortload of energy to use. ---
**Author:** ![lisiate](https://avatars.discourse-cdn.com/v4/letter/l/f05b48/32.png) [@lisiate](https://boards.straightdope.com/u/lisiate)\ **Post date:** [August 30, 2013, 3:08am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/5 "2013-08-30T03:08:01Z")
[Energy density](http://en.wikipedia.org/wiki/Energy_density)is the big limiting factor. Your 10-kilo weight limit means even if it’s all devoted to batteries you’ll only have 18 Megajoules of energy total - about the same energy as a cup and a half of petrol. Which can power your 100 kilowatt energy weapon for about 1.7 seconds I think. ---
**Author:** ![Terr](https://avatars.discourse-cdn.com/v4/letter/t/839c29/32.png) [@Terr](https://boards.straightdope.com/u/Terr)\ **Post date:** [August 30, 2013, 3:12am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/6 "2013-08-30T03:12:39Z")
> [@lisiate](#): > > [Energy density](http://en.wikipedia.org/wiki/Energy_density)is the big limiting factor. Your 10-kilo weight limit means even if it’s all devoted to batteries you’ll only have 18 Megajoules of energy total - about the same energy as a cup and a half of petrol. Which can power your 100 kilowatt energy weapon for about 1.7 seconds I think. See matter/antimatter thing upthread. Containment, though, is a bitch. ---
**Author:** ![Mister\_Rik](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mister_rik/32/491_2.png) [@Mister\_Rik](https://boards.straightdope.com/u/Mister_Rik)\ **Post date:** [August 30, 2013, 3:32am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/7 "2013-08-30T03:32:42Z")
So, basically, a handheld, 1920s-style death ray? ---
**Author:** ![Habeed](https://avatars.discourse-cdn.com/v4/letter/h/a587f6/32.png) [@Habeed](https://boards.straightdope.com/u/Habeed)\ **Post date:** [August 30, 2013, 4:38pm UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/8 "2013-08-30T16:38:30Z")
Antimatter doesn’t count. An electron-positron pair annihilation releases 511 KeV gamma rays - see the listed constraints. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [August 30, 2013, 9:17pm UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/9 "2013-08-30T21:17:17Z")
So shield the gamma rays and use the other energy to power your laser. Antimatter/matter is still the absolute limit on energy density. Nothing can possibly ever be better. We’ve driven a surveyor’s stake into the ground, establishing the absolute upper end of weapons efficiency. Because of the need for containment, shielding, etc., the real “best possible” weapon will be somewhere below the position of that end-point. You invoked the “known rules of physics” but then immediately violated them by allowing us to arrange matter in “any arbitrary configuration that is stable.” This means we’re working with speculative future technology which we cannot, now, predict. BTW, why exclude gamma rays? They could make a fairly effective weapon. Would you want to stand in front of someone’s gamma ray gun? (No, not you, Dr. Banner. We know your opinion.) ---
**Author:** ![Habeed](https://avatars.discourse-cdn.com/v4/letter/h/a587f6/32.png) [@Habeed](https://boards.straightdope.com/u/Habeed)\ **Post date:** [August 30, 2013, 9:19pm UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/10 "2013-08-30T21:19:43Z")
You can’t shield the gamma rays - 10 kg weight limit. It requires known physics - by “any configuration that is stable”, I meant you can state “carbon nanotube batteries” or some other exotic material we know exists but cannot make in quantity. We do have to know about it, today, or it isn’t valid. I’m trying to ask if someone could design a ray gun using a CAD system today, and have a reasonable confidence it would work, even if they could not manufacture it. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [August 30, 2013, 9:28pm UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/11 "2013-08-30T21:28:59Z")
> [@Trinopus](#): > > So shield the gamma rays and use the other energy to power your laser. Antimatter/matter is still the absolute limit on energy density. Nothing can possibly ever be better. We’ve driven a surveyor’s stake into the ground, establishing the absolute upper end of weapons efficiency. > > Because of the need for containment, shielding, etc., the real “best possible” weapon will be somewhere below the position of that end-point. > > You invoked the “known rules of physics” but then immediately violated them by allowing us to arrange matter in “any arbitrary configuration that is stable.” This means we’re working with speculative future technology which we cannot, now, predict. > > BTW, why exclude gamma rays? They could make a fairly effective weapon. Would you want to stand in front of someone’s gamma ray gun? (No, not you, Dr. Banner. We know your opinion.) Well, most gamma ray sources are effectively omnidirectional. So they’re more dangerous to the person holding the gun than the target (thanks to the inverse square rule). And you don’t have enough in your 10kg weight limit allowance to meaningfully shield a decent gamma source so that the death rays only come out in the intended direction. ---
**Author:** ![Do\_Not\_Taunt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/do_not_taunt/32/2968_2.png) [@Do\_Not\_Taunt](https://boards.straightdope.com/u/Do_Not_Taunt)\ **Post date:** [August 30, 2013, 11:11pm UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/12 "2013-08-30T23:11:28Z")
> [@lisiate](#): > > [Energy density](http://en.wikipedia.org/wiki/Energy_density)is the big limiting factor. Your 10-kilo weight limit means even if it’s all devoted to batteries you’ll only have 18 Megajoules of energy total - about the same energy as a cup and a half of petrol. Which can power your 100 kilowatt energy weapon for about 1.7 seconds I think. 18 Megajoules is 18 million joules. 100 kilowatts is 100 thousand joules per second. So my division gives you 180 seconds, or 3 minutes, assuming no waste. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [August 31, 2013, 1:50am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/13 "2013-08-31T01:50:37Z")
The [Atomic Rockets](http://www.projectrho.com/public_html/rocket/index.php) site has a page devoted entirely to the pros and cons of [energy sidearms](http://www.projectrho.com/public_html/rocket/sidearmenergy.php). It addresses several problems with the concept. Energy density of power source, waste heat, and especially the problem that any electromagnetic beam (laser, etc.) powerful enough to burn a hole through its target is going to backscatter enough energy to maim or kill the gun wielder. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [August 31, 2013, 2:58am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/14 "2013-08-31T02:58:44Z")
> [@Mister\_Rik](#): > > So, basically, a handheld, 1920s-style death ray? They didn’t go hand-held until the early thirties. ---
**Author:** ![dropzone](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dropzone/32/7515_2.png) [@dropzone](https://boards.straightdope.com/u/dropzone)\ **Post date:** [August 31, 2013, 5:36am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/15 "2013-08-31T05:36:36Z")
> [@Johnny\_L.A](#): > > Kinetic energy weapons are quite common. 😉😃 And this is why the gunpowder-based handguns in _Firefly_ make much more sense than phasers and blasters. Handheld energy weapons are a fun intellectual exercise and I don’t want to derail the thread. I mean, it’s brainstorming and there are no bad ideas in a brainstorming session. [However, Arte Johnson and Peter Sellers say it best.](http://www.youtube.com/watch?v=XkFx3TaOunA)😉 ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [August 31, 2013, 6:31am UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/16 "2013-08-31T06:31:35Z")
> [@Habeed](#): > > Could you build a “hand held” energy source in a weapon that produced, say, 100 kilowatts of continuous electric power, and could fire until the waste heat made it too hot to handle? > … > Chemical energy sources won’t do it… Why are you dismissing chemical energy? 10 kilograms of gasoline contains about 460 MJ of energy. That’s 100 kilowatt x 4600 seconds. If you can get the total efficiency to 1%, you have 46 seconds of use, which seems sufficient for a hand-held weapon. ---
**Author:** ![Habeed](https://avatars.discourse-cdn.com/v4/letter/h/a587f6/32.png) [@Habeed](https://boards.straightdope.com/u/Habeed)\ **Post date:** [August 31, 2013, 5:39pm UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/17 "2013-08-31T17:39:10Z")
> [@scr4](#): > > Why are you dismissing chemical energy? 10 kilograms of gasoline contains about 460 MJ of energy. That’s 100 kilowatt x 4600 seconds. If you can get the total efficiency to 1%, you have 46 seconds of use, which seems sufficient for a hand-held weapon. That fails to meet the stated constraint of “could fire indefinitely, limited by waste heat”. Weaponry like this is a sci-fi trope. In order for it to work, a form of nuclear energy that does not release gamma rays is probably the only valid solution. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [August 31, 2013, 6:53pm UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/18 "2013-08-31T18:53:04Z")
> [@Habeed](#): > > That fails to meet the stated constraint of “could fire indefinitely, limited by waste heat”. You only said “fire until the waste heat made it too hot to handle,” which is very different from “indefinitely”. I took it to mean the weapon overheats before the energy source runs out. > [@](#): > > Weaponry like this is a sci-fi trope. In order for it to work, a form of nuclear energy that does not release gamma rays is probably the only valid solution. I don’t recall any sci-fi weapons having an unlimited power source. Star Trek phasers had power cells that needed to be recharged, for example. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 31, 2013, 6:57pm UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/19 "2013-08-31T18:57:59Z")
And gamma rays are a feature, not a bug. You just need to figure out a way to make them only come out the front, not the sides. ---
**Author:** ![dstarfire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dstarfire/32/5762_2.png) [@dstarfire](https://boards.straightdope.com/u/dstarfire)\ **Post date:** [August 31, 2013, 8:36pm UTC](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557/20 "2013-08-31T20:36:29Z")
So, atomics radiation is out (spiralling into debate of issues irrelevant to this scenario). But what about the old “nuke in a tube” sci-fi trope? Also, what about lasers? I know the Navy has shot down a target drone with a laser. How about microwaves? The Army has a crowd suppression system that uses specially tuned microwaves to create a sunburn-like sensation. Could you tune it instead to boil a person’s tissues while still meeting the OP’s requirements? [Next page](https://boards.straightdope.com/t/are-hand-held-high-energy-weapons-possible-via-known-physics/667557.md?page=2)