Lasers

>With no contaminants in the air at all, just a pure gas
So no Oxygen?

>>57461787
An oxygen mix is fine. Just no solid contaminants.

>>57461765
Yes. However, you need one that the gas is opaque to. If it's a clear gas, you'll have to use wavelengths outside of the visible spectrum. Also, you might need a quite powerful laser unless you can contain the heat in spot.

>>57461865
Do you have a source or anything? I'm having a disagreement and the asshole wont listen without any proof.

>>57461903
That's basic physics knowledge. Point him to a wiki article about optics or something.

>>57461922
Alternatively, try to find something via google about heating gases with light/laser beams. If you can find anything that heats a gas above the ignition point of methane or hydrogen, you've won.

>>57461903
Ask him what is needed for fire. Then ask him if they're all present in an oxygen gas mixture with a laser.

>>57461903
It's not that hard. If the gas is not opaque to the laser, it's absorbing the light. Light is just energy. So what does the gas do with it? Turns it into heat.

The stronger the laser, the further it will shine through non opaque gas, thus splitting the energy on this path. Having a stronger laser will not make any point absorb that much more energy.

No, you cannot light methane with a laser. If you had some really dark non reflective smoggy gas with a low burning point then you could do it.

>>57462020
There are wavelengths methane, or oxygen, or nitrogen, or hydrogen are opaque to, which allows you to heat and ignite a gas.

>>57461765

>lasers

go back to >>>/x/ you fucking schizo
this isn't a science fiction larp outlet for your stupid cartoon fantasies

>>57461765
Yes, but Im too lazy to give links that i found in 30 seconds of googling. Go look it up you lazy faggot.

>>57461952
This, if you can't see the laser reflection in the gas it's likely just going through it without any significant energy getting absorbed
Of course lasers operate in much more than the visible light spectrum, it's practically impossible to get no light absorption from any gas

With one powerful enough, yes. Exactly how powerful, I don't know.

yes

depends on the molecule/atom and depends on the laser/intensity

>>57461765
You need a very powerfull impulse laser and you need to focus it in a point where the gas is. if you do that you can create a small plasma point mid air wich will ignite the gas.
A laser that powerfull usualy needs liquid nitrogen to cool down, its gigantic and costs a few million.
Source: I have a physics major and have worked with one at uni.

>>57464282
Oh and a gas is probably one of the very few things you can burn with it focused, cause anything else just vaporises before it gets a chance to burn.

>>57464282
>>57464356
There are colourless gases with autoignition temperatures as low as 21 degrees Celsius or lower. I doubt you need to create a localised plasma to ignite gas.

>>57461765
>OP is trying to set his farts on fire with a laser

>>57464994
http://www.9news.com.au/world/2016/11/01/13/03/fart-burns-woman/?ocid=9newsfb

File: 1266283879014.jpg (4KB, 126x79px) Image search: [Google]

4KB, 126x79px

>>57465028
>I hope this is real

File: 1457543345216.png (25KB, 500x501px) Image search: [Google]

25KB, 500x501px

>>57462444
>lasers aren't real