Ask a physicist anything. (3)

[KIYX]

I think you might have missed all the quests leading up to it. Early on, there was one where you pretend to join an end-of-times cult and wear a sign, preaching about the end of the world. It kind of reminded me of these forums. lol

I've been playing wow for over 3 years and I have to say I haven't enjoyed myself this much in a long time.

Go to Western Plaguelands and do the quests there... it'll be more helpful if your lvl 30.

 

[Wiccan_Child]

...unless you're talking about the stereotypical WoW addict.

I'm friends with WoW addicts, nothing stereotypical about it

 

[Supreme]

More a chemistry question, but can you get postive electrons and negative protons?

 

[Cabal]

More a chemistry question, but can you get postive electrons and negative protons?

Antimatter.

(well, sort of. I think it still needs to be experimentally verified whether or not antimatter falls downwards under gravity, but I could have heard that wrong.)

 

[Wiccan_Child]

More a chemistry question, but can you get postive electrons and negative protons?

No... though their antimatter counterparts, the positron and antiproton, have virtually exactly the same properties (mass, etc), and the exact opposite charge.

So while you can't get positive electrons technically, the positron is pretty much a positive electron. Hence the name

 

[Lillen]

I don't know how I can set forth the following problem... But how can light travell through space - It has nothing to interact with?

 

[Cabal]

I don't know how I can set forth the following problem... But how can light travell through space - It has nothing to interact with?

Light doesn't require a medium to travel.

Although one could argue that the "vacuum" is a medium in its own right. It's certainly not inert in other contexts.

 

[Wiccan_Child]

I don't know how I can set forth the following problem... But how can light travell through space - It has nothing to interact with?

Well, why can't it travel through space? It doesn't need something to interact with, does it?

I suppose you could question with respect to what is it travelling at c...

 

[Lillen]

How can it be visible, it has nothing to interact with?

 

[Cabal]

How can it be visible, it has nothing to interact with?

Detection and propagation are two different matters.

 

[PhoceanCity]

How can it be visible, it has nothing to interact with?

Someone can correct me if I'm wrong but it interact with your eye, the captor of a camera or any photosensitive material.

 

[Lillen]

Well, why can't it travel through space? It doesn't need something to interact with, does it?

Inorder for it to be visible yes! It should be absorbed since space is black?

 

[Cabal]

Inorder for it to be visible yes! It should be absorbed since space is black?

Black isn't a colour caused by the presence of visible light, but rather its absence.

 

[Lillen]

Thats what i said cabal. So how can ligth travell through the abscence of light during night?

 

[Lillen]

Why is the space black, space has to be the abscence of light?

 

[Wiccan_Child]

Why are the space black, it is the abscence of light? is it not?

Space looks black because there's no light there. Space isn't a big sponge that absorbs light, it's an empty void through which light can travel unimpeded.

 

[Cabal]

Thats what i said cabal. So how can ligth travell through the abscence of light during night?

Because it's not interacting with anything, so it goes straight through unimpeded. Like Wiccan_Child said, it's not dark because it's absorbing, it's dark because there really just is nothing (visible) there.

Why is the space black, space has to be the abscence of light?

Well, it's not really a matter of "has to be". It just is that way because it's largely empty. Very little light is received in all directions apart from the light heading away from the light sources in space themselves.

 

[Lillen]

So in other words, light is invisible in space?

 

[Cabal]

So in other words, light is invisible in space?

If you want to think of it that way, sure. You don't ever see light in transit (unless it's going through a scattering medium like air, and even then what you're actually seeing is the light that's being reflected, not the actual light that carries on in a straight line), you only over see it when it interacts with a detector.

 

[Wiccan_Child]

How can it be visible, it has nothing to interact with?

Because it comes from somewhere. The light we see when we look at a green pea looks green because the pea is emitting specifically green light. That's why it's green. If there's no light coming from a particular direction, we see that as 'dark' or 'black'.