1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Energy weapons: reality and fiction

  1. Aug 11, 2010 #1
    Hi all.
    Sorry if I am posting in a wrong section as I am new there and di not figure it out where my post belongs to.
    I would like to ask about energy weapons in fiction and reality. We have movies, video games, novels where lots of weapons (of different designs) are used. As far as I understand, only laser weapons may be used in our days, although without such a devastating effect (like Death Star) or visual effects (like Star wars, where beam could be easily seen). Also, if I am not wrong - plasma weapons are very unlikely to function.
    The question is about reality of some science fiction weapons:
    1. ion cannon - not speaking about its effect (in star wars - blueish weapon, capable of disaablin ship; in master of Orion2 - yellowish weapons, bypassing armor)
    2. photon based beam weapons (some science fiction novels) - is it real or not?
  2. jcsd
  3. Aug 11, 2010 #2
    lasers are photon weapons...

    plasma would be pretty easy to deflect in smaller doses, but a ton of ions, with the associated heat from reactions, could be viable... like a plasma torch the size of a stadium.

    but i have very little info on the subject
  4. Aug 11, 2010 #3
    What about "proton torpedoes" (from Star wars), explained as "torpedoes with photon warheads"? They managed to use missiles (nuclear?), then - proton torpedoes. SOme writer even invented "proton grenades", little enough and still devastating.

    In this forum I have read ion cannon cannot be real (yes, that pretty strike from c&c - too).
    In such case: is there any other military technology usable in space,except laser weapons and nuclear warheads?
    "Master of Orion2" uses "Graviton beam", yet gravitons are something -if I am not wrong- yet to be found, something theoretical...or aren't they?
  5. Aug 11, 2010 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You might want to ask this question here: http://groups.google.com/group/rec.arts.sf.science

    It's going to be hard to get any kind of closed-ended answer to this, since there are so many different ways in which such things have been portrayed in SF, and there is a whole spectrum running from hard SF to soft SF.
  6. Aug 11, 2010 #5
    Oddly enough, I just saw a preprint which discusses the limitations of lasers intensity due to pair creation from the vacuum from the laser field.

    The preprint is here: http://arxiv.org/abs/1004.5398

    EDIT: to be a little more clear- this paper places a limit on the use of a lasers as cataclysmic weapons.
  7. Aug 12, 2010 #6
    Well, the laser may be used as a "cut" weapon: think about "star wars" blasters, used by clone/storm troopers, not that fictional star destroyers' big greenish rays that travels too slow. While I can admit that laser colour may be corrected - the Big Ray would just make a hole, not blow up. Therefore, no "death stars". The only question about laser weapons (well, we are speaking about reality) is - are they capable of effectively cutting something?
    Example: a huge bridge stands and army B is defending it at all costs. Army A wants bridge to be destroyed, but all conventional attacks fails: missiles taken down,planes, helicopters, troops - everything is repelled. Then some bright mind brings up a powerfull laser and simply cuts columns that support the bridge, one by one. Hurray, victory.
    1st question: is that possible? The physical size of the laser does not matter and the energy can be obtained from neariest 10 nuclear power plants.
    2nd question - still about ion and alike cannons. Is it theoretically possible to create a beam that would be deadly when used in space (except laser)?
  8. Aug 12, 2010 #7
  9. Aug 12, 2010 #8
    Thanks for the link. Laser Avenger was the most usefull item there (not speaking about Israeli battle robot with 2 machine guns: not GDI walking tanks, but still...).
    ...and what about the laser cutting?
  10. Aug 12, 2010 #9
    Laser cutting of materials?
    Well, it's standard technology today, if that's what you mean.
  11. Aug 12, 2010 #10
    Well, I mean big distance (kilometres, or even thousands of them) and cutting, say, a part of well armoured battleship. Is it possible that hostile battleship A is approaching US border and they have a megacanon on the shore - and just cut that ship into 2 parts by one shot?
    Energy consumption is not crucial: let us presume out military guys may use all the powerplants within USA.
  12. Aug 12, 2010 #11
    The preprint I linked to places limits on the power of a laser. Remember that in a medium like an atmosphere, a laser will have a decrease in power with increasing distance. This fact coupled with the limits on laser power due to pair production from the vacuum makes the use of a laser as a weapon extremely unlikely.
  13. Aug 12, 2010 #12
    Norman, has e+e- pair production from lasers ever been demonstrated in a lab?

    But neither this, nor the atmosphere, prevents lasers from being used as weapons.
  14. Aug 12, 2010 #13
  15. Aug 12, 2010 #14
    Yes. See "[URL [Broken] Rev. Lett. 79, 1626–1629 (1997)
    I agree in the general sense. There are plenty of other issues for lasers as weapons (power mainly, I believe). I was merely considering the fanciful, crazy Star Wars death rays, etc. Cutting a bridge in half from a few miles away with a laser is not likely to be feasible.

    EDIT: Missed Gerenuks post. Nice read. Also, I am far from an expert in lasers. I am sure many more people on here (likely Dr Lots-o'watts included) are much more versed in the practical development and theory of lasers. I had a passing interest in grad school, but have not seriously thought about lasers in a few years.
    Last edited by a moderator: May 4, 2017
  16. Aug 12, 2010 #15
    And working full time in the laser industry doesn't make me an expert in every aspect. Is has become a very wide field.
  17. Aug 16, 2010 #16
    We have micro tractor beams that can trap and move dielectric particles around the size of bacteria. They're called laser tweezers and optical traps. Technically, you can make one with pretty much any kind of laser, even a laser pointer, and an objective. They're not big enough to trap any spaceships, but I bet we have bacteria shaking in their little membranes.
  18. Aug 17, 2010 #17


    User Avatar
    Science Advisor
    Homework Helper

    Laser tend to be line of sight - so if they are used their only viable purpose is close quarter anti-missile defenses.
  19. Aug 17, 2010 #18


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    http://en.wikipedia.org/wiki/Boeing_YAL-1" [Broken]
    The USAF have tested an airborne chemical laser which actually works; blasts tanks etc.. It seems to be the nearest thing to Star Wars weaponry to date.
    Electrically powered lasers are very inefficient and the chemical laser gives the required 'population inversion' when you mix the two appropriate chemicals together. You bet far more bang per buck's worth of fuel you carry on board if you don't use electrical energy as an intermediate stage.
    Last edited by a moderator: May 4, 2017
  20. Aug 17, 2010 #19


    User Avatar
    Science Advisor
    Homework Helper

    Blasts tanks is a little optimistic - it might (just about on a good day with a following wind...) burst a liquid fueled ICBM's fuel tanks
    This is from a device that takes an entire 747 with enough nasty chemicals on board that you would do rather more damage to the target by simply landing on it.
  21. Aug 17, 2010 #20


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    You spoilsport. It's a start ain't it?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook