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[Duke 2.0]

 Names stick. Also, would you rather be shooting Dark Matter lasers or HR-12 theoretical particle emitters?

[Leafsnail]

Names stick. Also, would you rather be shooting Dark Matter lasers or HR-12 theoretical particle emitters?

Dark matter particles are, according to the theory, massive, but so weakly interacting that they've only been very slightly hinted at by some experiments.  An dark matter ray would do damage so small that it couldn't be measured.

[Virex]

Names stick. Also, would you rather be shooting Dark Matter lasers or HR-12 theoretical particle emitters?

Dark matter particles are, according to the theory, massive, but so weakly interacting that they've only been very slightly hinted at by some experiments.  An dark matter ray would do damage so small that it couldn't be measured.

More acurately, they're believed to interact with normal mater through gravity primarely. Considering that gravity is the weakest of the elementary forces, that does say something.

[bjlong]

Dark matter is still a commonly used term. It refers to what is thought to be weakly interacting particles changing the spin of galaxies. (The error between how we think a galaxy should spin and how it does spin is enormous the further you go out.)

Dark Energy is thought of as "negative gravity." It's uses to explain the expansion of the universe.

The only real correlation between the two is that we don't know where these things are or where they come from, and they have the word "dark" in their names.

[Cthulhu]

If I invented a gun using that part of physics that doesn't make any sense, I'd call it the Doomzappy.

[Areyar]

I don't think a matter+dark matter reaction is possible: the basic principle of DM is that it will not interact with photonic matter except by gravity. hence the 'dark' bit, it is not actually there according to conventional observation.

light momentum: photons have mass, light has velocity -i> mass+speed = momentum.
As a special rule, light cannot be slowed down (from the lightspeed in a given medium).
ed: don't have an official edu in partcle physics, so meh.

From practical application: lightsails can impart momentum from solar light.

[bjlong]

Photons specifically don't have mass. If they did, they'd not be able to travel at the speed of light. It's a relativity problem. See the above posts on momentum.

Doomzappy is a good name. So is Boomstick. And Dan.

[Virex]

Photons specifically don't have mass. If they did, they'd not be able to travel at the speed of light. It's a relativity problem. See the above posts on momentum.

Correction, (and I would have given it a capitol C even if I didn't properly punctuate my posts) it doesn't have a rest mass. But light does have energy and since energy and mass are essentialy two sides of the same coin, one could say that light has some sort of mass. However, since it doesn't have a rest mass, nearly everything dealing with mass doesn't count for it. Those laws generaly deal with rest mass and not "energy mass"

[bjlong]

Apologies, this is correct. However, this mass is unlike any that we experience in our day-to-day lives, so I find it much easier to explain as a "massless particle," with the caveats thrown in if people seem interested.

[Grek]

When dealing with reletivity, it is better to just say p=(m+e)v/c^2