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Science fiction: what is the green goo in Half-Life?

  1. Aug 11, 2012 #1
    This being a physics forum, I'm sure many of you have heard of the 1998 computer game Half-Life.

    If you don't know, the game is set within a top secret research laboratory deep within the deserts and mesas of Arizona. All hell breaks loose after a massive screwed-up experiment. The protagonist is a theoretical physicist who has to somehow survive.

    Anyway, at the start of the game you travel across a canal filled with some glowing green sludge.

    (its near the end of this video)

    I'm extremely curious as to what the sludge could be. Apparently its radioactive. But does radioactive fluid glow like that? Is there such a thing in real life?

    In the game there is also a weapon called the Gluon Gun. Its pure fiction, but I wonder, is it possible to create a stream of gluons like a stream of photons? A gluon "laser" perhaps? After all, gluons can all occupy the same quantum state.
  2. jcsd
  3. Aug 11, 2012 #2


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    The "green glowing goo" is just a video game cliche. Kind of like exploding barrels.
  4. Aug 11, 2012 #3
    what about the gluon laser? Is it possible to create one?
  5. Aug 11, 2012 #4


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    What do you mean by "gluon laser"?
  6. Aug 11, 2012 #5
    similar to a conventional photon laser, but using gluons instead.
  7. Aug 11, 2012 #6


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    Water does glow in presence of certain kinds of radiation, but the real glow is blue. Here is a picture. Green glow being associated with radiation in popular culture has most likely started due to phosphorus having a greenish-yellowish glow in presence of radiation. This has been used both for detecting radiation early on, and later for various glow in the dark paints.

    Gluons are color-charged, and so cannot exist as free particles. It might be theoretically possible to lase glue balls, but by itself, concept of gluon laser makes no sense.
  8. Aug 12, 2012 #7
    I've never been able to understand why there is constructive interference when a β-particle flies through the water at a speed faster than the local speed of light.

    I've always thought that its due to the particle slowing down to the local speed of light and losing energy in the process.

    Besides that, I've heard that radioactive cesium gives off a blue glow. A la Goiânia accident. But I can't find any picture of that.
  9. Aug 12, 2012 #8
    The green liquid can be seen in Half Life 2 as well and represents some sort of radioactive waste associated with the technology of the aliens. Green is just a popular color to use for backgrounds in horror films and video games because it helps to compensate for the poor contrast of LCD monitors and any fluctuation in the lighting. It's become an especially popular choice in modern video games because blue is considered too pretty and red is used for blood and to indicate damage to your character. That leaves green as the color of choice for symbolizing darkness and all things gross and evil.

    You might think such lighting and color choices are trivial, but the fact is they are far from trivial. Films and video games can be played in anything from a completely dark room to one lit by daylight and reflections on the screen and the lighting of the room in general can make a huge difference in the perceptible contrast. Between that and the already low contrast of common LCD displays a poor choice in colors and lighting can ruin the experience with some scenes becoming completely black and unviewable without some sort of compensation. Even with the infinite contrast of OLED displays so long as the ambient room lighting remains a huge variable there is no other way to make them short of introducing some sort of new technology that can automatically compensate for ambient lighting. There are plenty of other technical problems that also contribute to the widespread use of green as a background color and this is just the quick and dirty explanation.
    Last edited: Aug 12, 2012
  10. Jan 3, 2013 #9
    @K2 - phosphorus does not give greenish-yellowish glow in presence of radiation. There are materials called phosphor which do and they have particular lattice + impurity structures to do so. However, white phosphorus slowly burns without emitting heat in contact with O2 with a green glow (chemiluminescence).
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