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[RedWarrior0]

Photons have no rest mass because, as something gains velocity, its mass increases. Specifically, relativistic mass is rest mass over sqrt(1-v²/c²). As a result, anything with nonzero rest mass moving at c is going to have undefined observed mass, no matter how small that rest mass is. Moving faster or slower than c is fine, but you might end up with imaginary components to mass/energy.

[TheProphet]

I believe this belongs in the various physics threads. But since I doubt it's going to move that easily, I'll chip in. I'm not convinced a photon is actually without mass. Ridiculously small, I have no doubt. In fact, I have no doubt in my mind that if a photon particle were at rest, it would be so small that we could not measure it with our modern equipment. But the fact that it has inertia says there must be something the energy is attached to. It also works with my theory that black holes are just super compressed matter, and that all the distortion and phenomena that surrounds them is just super gravity working it's magic on it's contents and everything around it. If a photon has mass, surely gravity would have an effect on it, and a black hole is strong enough to be easily noticed. Time would not be a factor.

But we are getting off topic, and in dire need of more WTF. I'll get us started.

I suggest you read "A Brief History of Time" by Stephen Hawking. Should give you a good intro to the subject.

[kaijyuu]

A photon having non-zero rest mass would require it to have infinite energy to attain the speed of light. Since we're not all spontaneously exploding when hit with a photon, it's pretty safe to assume it has zero mass.


I suppose you could argue that its mass is so tiny that it LOOKS like its going the speed of light but is going an incredibly small amount slower, but we've seen no measurable evidence of that.

[Max White]

You are making an interesting assumption there. You see it takes an infinite amount of energy for something to accelerate to the speed of light over non-zero time, but if a photon reached the speed of light with no acceleration then that should be fine, and I have never heard of one going at less than the speed of light because it hasn't got up to speed yet...

[Aklyon]

If a Daggerfall Guard and a photon meet, who halts first?

[Karnewarrior]

You are making an interesting assumption there. You see it takes an infinite amount of energy for something to accelerate to the speed of light over non-zero time, but if a photon reached the speed of light with no acceleration then that should be fine, and I have never heard of one going at less than the speed of light because it hasn't got up to speed yet...

Good point. What happens when light is slowed by one medium and then released into a medium it can go through faster? Does it speed back up? Then something is pushing it. Does it stay the same? Then we can stop it and measure it's mass and weight and all. Maybe even powder it eventually.

Powdered light. Just add battery acid!

[TheBronzePickle]

It doesn't 'slow down' when it goes through a medium where it goes slower. It hits the electromagnetic field of the atoms in the medium and makes one or a few of the electrons more energetic. The electrons can't hold on to this energy, so they quickly release it as more light which travels on roughly the same path as the original light. This happens slower than the actual speed of light does, though, so the light travels 'slower' even though it's still the same speed.

[612DwarfAvenue]

So, slight derail here but i've been wondering about this for ages: I'm probably missing something here, but why does everyone assume lightspeed is the fastest speed possible, that nothing can go faster than light*? Is it possible we simply haven't found anything faster than light just yet?

*And don't say space. Space is an absence of something, i'm talking about something quantifiable.

[Darvi]

Relativity. Because of physycks, an object aproaching c gains NI mass, which increases the energy necessary to accelerate it. At exactly c you divide by zero meaning that you need infinite energy to get to that speed, unless you don't have any mass.

[Max White]

So, slight derail here but i've been wondering about this for ages: I'm probably missing something here, but why does everyone assume lightspeed is the fastest speed possible, that nothing can go faster than light*? Is it possible we simply haven't found anything faster than light just yet?

*And don't say space. Space is an absence of something, i'm talking about something quantifiable.

Because relativity is a thing. The more you put energy into something, the more energy is required for acceleration of the same magnitude. This means that if you graph energy to acceleration, you get a line that approaches, but never reaches the speed of light.

Ninja'd.

[ChairmanPoo]

My current immediate superior is capital H hot. I find my mind wandering all too often

[Lagslayer]

There seem to be quite a few differences in how those within the physics circle define things, and how it all gets sensationalized to the public. So many inconsistencies that need to be cleared up before we continue.

My current immediate superior is capital H hot. I find my mind wandering all too often

Huh?

[olemars]

My current immediate superior is capital H hot. I find my mind wandering all too often

Huh?

Let's just say there's an attractive woman a bit to the left of ChairmanPoo's avatar.

[Lagslayer]

My current immediate superior is capital H hot. I find my mind wandering all too often

Huh?

Let's just say there's an attractive woman a bit to the left of ChairmanPoo's avatar.

Oh, hot as in attractive. NVM, I understand now.

[Nadaka]

My current immediate superior is capital H hot. I find my mind wandering all too often

Huh?

Let's just say there's an attractive woman a bit to the left of ChairmanPoo's avatar.

Oh, hot as in attractive. NVM, I understand now.

No man, she is literally on fire. A burning person is somewhat distracting in most work environments.