sci-fi weapons and focal points

[athon]

For the physicists here:

I'm picturing a sci-fi weapon - it uses a wavelength of light that can pass through skin, but if it uses a focal point beneath the flesh it will concentrate at a point and cause burns.

I'm researching for a friend who wants to write a short story using a concept like this. Is this a conceivable concept? Could you focus a laser beneath skin and burn, say, bone or muscle and leave little to no sign on the surface?

Athon

[davidhorman]

Hmm, interesting, but I'd think that to have a beam focused inside the body, and not so focused at the skin that it would burn there, would need a huge and very accurate transmitter (that's just layman's guesswork).

There is/was a technique for dealing with brain tumours called Stereotaxia - they'd fire radio waves from multiple sources at the tumour. A single radio source wouldn't do any damage, and would pass through the rest of the brain, but where all the sources lined up it would destroy the tumour.

David

[Nucular]

Ooooh ooh, sounds like in Dr Who, the (I think) disruptor beam?

"Doctor, he looks okay"
"Hmm, disruptor beam - insides are a mess"

It may or may not have been a device to avoid having to fork out for expensive 'horrific injuries' make-up on a tiny budget, but I remember thinking "cool!" (in a non-serial killer way, of course).

[davidhorman]

Are you thinking of Remembrance of the Daleks? Young squaddie gets in the line of fire and *zblat*, gets hit by a bolt of blue light, throwing him backwards and momentarily revealing his skeleton. It was one of the best effects they ever had on that show (another being the floating coffin in a later episode of that story).

I think the technical word used by the Doctor was "scrambled" :D

David

[Nucular]

Originally posted by davidhorman
Are you thinking of Remembrance of the Daleks? Young squaddie gets in the line of fire and *zblat*, gets hit by a bolt of blue light, throwing him backwards and momentarily revealing his skeleton. It was one of the best effects they ever had on that show (another being the floating coffin in a later episode of that story).

I think the technical word used by the Doctor was "scrambled" :D

David Yes! I think it was! Was that Sylvester McCoy?

[davidhorman]

Yes! I think it was! Was that Sylvester McCoy?

Yup - and I met him a couple of weeks ago and got his autograph :D

I'm remembering more of that scene now.. he has a quick feel around the squaddie and pronounces the cause of death as "massive internal displacement", if i remember correctly. And that squaddie was already dead, it was a second later that buys it on screen.

David

[wollery]

Originally posted by athon
For the physicists here:

I'm picturing a sci-fi weapon - it uses a wavelength of light that can pass through skin, but if it uses a focal point beneath the flesh it will concentrate at a point and cause burns.

I'm researching for a friend who wants to write a short story using a concept like this. Is this a conceivable concept? Could you focus a laser beneath skin and burn, say, bone or muscle and leave little to no sign on the surface?

Athon

Actually all you'd need is a wavelength that would pass through skin but not bone. Don't ask me what wavelength, the only one I can think of is X-ray, and you'd need one hell of a massive generator to produce enough X-ray power to do serious enough damage for a weapon. For the idea of focussing to work you need to figure out a way to accurately (and actively) range find which feeds into a very precise beam focuser. Can't see it being practical, but then it is for a fiction story! :D

ps just thought, the difference between the beam travel length to the skin and the focal point would probably be too small, unless the beam emitter was quite wide, or the weapon was used from very close range. You'd end up with a virtual focus on the skin.

Oh well, just a couple of random thoughts! :cool:

[Hexxenhammer]

Better not use the word "laser" I would think.
The weapon could have 2 or more emitters that focus the Q-beam (or whatever) under the skin.

[daver]

The concept sounds vaguely familiar. Maybe i'm thinking of time-reversed sound waves being used to shatter kidney stones without surgery. Maybe a similar concept could be used to focus light through a translucent medium.

[Soapy Sam]

Electromagnetic induction weapons. Remote ball lightning generator in effect. Two focussed EM fields interact at a preset point to produce an interference standing wave which manifests as a plasma ball. Hiding behind something is pointless. The explosion due to the plasma ball can be very small, as aim is precise. (Inside the head of a fighter pilot for instance). Clearly, there would be an inverse square range limit, but you just use a bigger generator. Hand versions would be limited to pistol range, full battlefield jobs could take out tanks, towns, you name it.
Fiddly things to set of course, so the fire rate is low, but then every one's a hit. If you are shooting back with a rifle, your only hope is your higher rate of fire.

As used by the garlesqueeg battalions of the Squelk Sector.

Feel free to use. I hope it's total nonsense.
(My Stimpy Detector is starting to flash! Start the generators).

[TillEulenspiegel]

Actually these type of devices do exist in hospitals, they focus positrons or X-Rays to a particular area ( mostly used for inoperable brain tumors) and destroy only the cancerous/ tumor tissue. The machines take up two rooms , cost a kabillion bux , and require complete stillness on the part of the patient. The cost in energy is huge , the cost id dollars is in the millions. So does the concept seem viable yes... for a mass produced, hand held weapon ..err, coff,coff

[Nucular]

Originally posted by TillEulenspiegel
for a mass produced, hand held weapon ..err, coff,coff Why mass produced, why hand-held? Daleks don't have hands.

[Nucular]

Originally posted by davidhorman
Yup - and I met him a couple of weeks ago and got his autograph :D:eek: Sir, I am impressed.

[EdipisReks]

Originally posted by Nucular
Why mass produced, why hand-held? Daleks don't have hands.

the toilet plungers are certainly close enough ;)

[teddygrahams]

http://www.imdb.com/Title?0060548

Now if some of these things were made invisible and launched from a cannon at the intended victim you could have some good effects.

[Reginald]

Microwaves?

If focused at depth they could generate a lot of damage and you can make some very very powerful emiters. Im thinking superheated steam, internal explosions......hmmmm.

Mind you the counter measures would be fairly simple to get.

[RSLancastr]

Sounds like a microwave oven to me...

[Reginald]

Originally posted by RSLancastr
Sounds like a microwave oven to me...

:D

[neutrino_cannon]

How about this: Use a particle that does not interact with matter (usualy) but decays at a set rate. At about the time when the particles converge on the focus of the weapon (some distance inside the target) the particles decay into other particles that do interact with normal matter, as well as giving off energy, thereby frying the innards of the target without losing an energy into the tissue the flood of particles went through.

This sort of decay has been observed in various particles, but you might want to do more research before your friend uses the concept. One particle that has been observed to transmute is the neutrino. You could have a neutrino cannon!

[Diamond]

Originally posted by TillEulenspiegel
Actually these type of devices do exist in hospitals, they focus positrons or X-Rays to a particular area..........

They store positrons in hospitals ready for use? That's got to be risky....

[neutrino_cannon]

Originally posted by Diamond


They store positrons in hospitals ready for use? That's got to be risky....

I think they're refering to positron emmisions topography (PET). An isotope of something or another is absorbed into the brain tissue at differential rates based on the activity there. The positrons are spontainiously emited by the something or another, and the gamma ras given off by the resultant annihilations can be measured to give an idea of what the brain is doing where.

It's poor man's MRI as I understand it.

[athon]

Originally posted by TillEulenspiegel
Actually these type of devices do exist in hospitals, they focus positrons or X-Rays to a particular area ( mostly used for inoperable brain tumors) and destroy only the cancerous/ tumor tissue. The machines take up two rooms , cost a kabillion bux , and require complete stillness on the part of the patient. The cost in energy is huge , the cost id dollars is in the millions. So does the concept seem viable yes... for a mass produced, hand held weapon ..err, coff,coff

I thought this was the case. I just wanted to be certain the basic principles were sound.

As for everybody else's ideas, I think we have a few good sci-fi writers here. Then again, when you spend any amount of time exploring paranormal claims, you get a feel for how good science fiction works.

Cheers,

Athon

[sorgoth]

For the big guns...use solar charged satellites, that orbit the earth so that they're always in the sun. I figure, you get three or so, aim them all so they converge on a target, and send rays that make the convergence point burn.

[neutrino_cannon]

Originally posted by sorgoth
For the big guns...use solar charged satellites, that orbit the earth so that they're always in the sun. I figure, you get three or so, aim them all so they converge on a target, and send rays that make the convergence point burn.

It's easier than that. Solar sails, big pieces of really thin mylar are being investigated as a cheap way to get around in the solar system, since the pressure of photons is essentialy indefinate. Simply take your three square mile solar sail, focus into parabola, and viola! Solar powered weapon of mass destruction! Smite countless people from the face of the earth and at the same time tap into renewable energy!

[Diamond]

Originally posted by neutrino_cannon


It's easier than that. Solar sails, big pieces of really thin mylar are being investigated as a cheap way to get around in the solar system, since the pressure of photons is essentialy indefinate. Simply take your three square mile solar sail, focus into parabola, and viola! Solar powered weapon of mass destruction! Smite countless people from the face of the earth and at the same time tap into renewable energy!

Is this a WMD that burns up in the atmosphere on re-entry? Are you trying to scare people to death by showing them an artifical meteor?

[TillEulenspiegel]

Originally posted by athon


I thought this was the case. I just wanted to be certain the basic principles were sound.


Athon
Well I was inexact =) the impression i was trying to convey is the massive amounts of energy involved in either generation or focusing of those energies. If you think of a TV it has a small filliment in the back of the picture tube powered by 6 volts. Now we have to accelerate the electrons, that takes a field of 16,000+ plus volts ( not a lot of current ) , now we also have to focus the beam, that requires 500-700 volts and much current. Now thats OK for a statonary object like a TV or even a EM weapon gun turret, but not practical for a hand held weapon. Just remember that you cannot output more energy from a system then it contains. even in potential form. ( like an atomic explosion, which BTW you don't want to hold in you hand , unless your Ahhhnold)