/sci/ - Science & Math

Herp derp, Because it's light.

Because light is made of energy

>to move something with a mass

Here's a thought. If light had mass, light would have infinite energy.

Shame it doesn't have mass.

The rest mass of light is zero. So the amount that you need to move photons is 0 * infinity, that roughly is a finite value. Because of this effect you can gain electricity through photovoltaics.

>>1489464
Everything is made of energy. Or matter. Diffraction by a double slit also works for electrons or even protons.

>>1489491
Almost, once it moves, it also has a mass because it has some energy and therefore has an impulse.

>>1489491
>Shame it doesn't have mass

So /sci/ believes in ghosts.

>>1489491
>Shame it doesn't have mass.

Isn't a photon a particle?
Don't all particles have mass?

>>1489544
Oh, this isn't even funny.

light is 100% energy.
for something with mass to move at the speed of light it would have 100% energy too. But since it has mass it can never be 100% energy. Unless it has infinite enrgy.

>>1489546
I'm serious...All the science I learned was from comic books. I thought that light is made of photons and that photons are particles. I also thought that all particles have mass. Please set me straight.

>>1489544

Photons are both particles and waves, because it's a giant clusterfuck

>>1489554
There are plenty of particles that don't have mass. Photons, gluons and gravitons.

>>1489583
so do gluons and gravitons move at lightspeed?

>>1489589
Yes, just like photons.

So many chem/bio fags up in here

>PhD in mathematics
>any jon i want
>300k starting

can a photon move slower than the speed of light?

this is a serious question

>>1489615

no

>>1489589
um. i don't think we know yet. we don't have a good description of what might cause gravity on a partical scale level.

>>1489619
yes it only moves at the speed of light if travelling through a vacuum.
also they have mass when going through certain materials. don't know why though.

>>1489628

so there is no such thing as a stationary photon?

do any other particles exhibit this property?

>>1489622
Gravity is not described by the current standard model of physics. When we talk about gravitons, we mean "the field particle that is assumed to mediate the force of gravity", whatever it may be. Since gravity appears to have infinite range, such a particle is probably massless.

>>1489628
>yes it only moves at the speed of light if travelling through a vacuum.
Correct. In anything that isn't vacuum, photons will be scattered resulting in a lower speed. Imagine them bumping into the other atoms, going in a zig-zag pattern such that the average speed becomes lower.

>also they have mass when going through certain materials. don't know why though.
Photons may be described as massive particles in some non-mainstream theories, but probably not in the way you are suggesting. Photons are massless in any material.

>>1489912
Photons are energy and have the mass equivalent described in E = mc².
Their paths are bent by gravity fields and they impart a physical force on objects they impact.

Wave-Particle Duality, motherfucker. Do you speak it?

>>1489865
Depends on what you mean. Light can be slowed significantly using certain optical phenomena. If you were to "move along" with this light, it would appear stationary in your frame of reference. I've personally never heard of such a thing as a stationary photon in the lab frame.

>>1489948
They've managed to slow it down to a couple centimeters a second, though.

>>1489937
Not really, no. I don't understand how light can be both particles and waves at the same time. I know it is a fact, but I don't understand how it works.

>>1489453

Photons, unlike you, are not composed of subparticles of infinite laziness. To counteract the infinite laziness, an infinite amount of effort is required. Photons, however, not being lazy and all that, only take a slight suggestion to travel at the speed of light.

Maybe you too could go at the speed of light if you weren't being such a lazy ass all the time.

>>1489930
>Photons are energy and have the mass equivalent described in E = mc².

<span class="math">E = mc^2[/spoiler] is a simplification of the more strict formula <span class="math">\sqrt{E = (mc^2)^2 + (pc)^2}[/spoiler]. Is is obtained by putting <span class="math">p = 0[/spoiler], making it valid for non-relativistic (slow) particles. Since photons have no mass, their energy is correctly calculated using <span class="math">E = pc[/spoiler].

>Their paths are bent by gravity fields

Photons are affected by gravity because a massive body bends space around it, not because the photons have mass. Try googling geodesics or general relativity.

>and they impart a physical force on objects they impact.

This is good ol' transfer of momentum. Again, photons have momentum but not mass.

For the new/sci/fags that have never researched Einstein's expanded equation for E=mc^2, you'd realize that there are two types of masses: Relativistic and Rest mass. Rest mass is the mass most people are encountered by, Relativistic mass is mass at near-light speeds. Photons are bosons that have a rest mass of 0. Because they're always traveling at the speed of light, they have 100% relativistic mass. Also, in Einstein's expanded formula, E^2 - (pc)^2 = (mc^2)^2; where E = Energy, p = momentum (mv), c = Speed of Light, and m = rest mass.
As you can see, if an object, such as a photon, has no mass, the reduced equation becomes E = pc. This shows that light must always have a certain momentum in order to continue it's light-speed path.

>>1489951

It's actually a property of anything that carries energy, not specifically light. Everything has properties of both a particle and a wave. Just so happens that the wave-like properties of massive things are undetectable, so we established a different classification for the "particle" before realizing it.

>>1489980
<span class="math">E = \sqrt{(mc^2)^2 + (pc)^2}[/spoiler]

>>1489980
(the person whose post is right below yours that contains your information) most every refer to this one seeing how it has more general information regarding how light is affected by gravity, but look at my post to see the indepth (explanation for tards) explanation on why it reduces to E = pc.

I love it when someone besides me knows a thing or two about this topic <3

>greentext <span class="math">\sqrt{E = (mc^2)^2 + (pc)^2}[/spoiler]

>>1489513
>0 * infinity, that roughly is a finite value.

Come on /sci/, I thought you were smarter than this.

>>1489951
This is one of the things remedied by String Theory (if you believe in it). microscopic "things" (for the sake of simplicity at this point) are in the shape of coiled strings. The strings themselves are particle-like in how they exist in that base state. The strings can also vibrate in specific recurring patterns that can resemble wave-like effects.

>>1489951
They aren't. They are just particles.

>>1489999
samefag here with post above ^
FUCK YEAR QUADS

>>1489951
Here's a useful picture for you. Photons can be thought of as "wave packets", see gif. The main difference between the wave-picture and the particle-picture is that particles are pointlike whereas waves have a spread in space. It is essential to understand that there is no such thing as a pointlike particle. ALL particles have a minimum spread in space because of the uncertainty principle.

Look at the gif again. Clearly, it represents a wave. But the amplitude of the wave varies in space and time, sort of like a bubble traveling to the right. This bubble is the particle. Voilá, you now have something that manages to be a wave and a particle at the same time!

More technically, the amplitude of the wave at any point in space is proportional to the probability that the particle would actually be located at that point. Say you want to measure the position of the particle. The probability is high that you will detect the particle somewhere where the amplitude of the wave packet is large. The probability is zero to detect the particle somewhere where the wave packet has no amplitude.

There is a lot more to be said about wave packets, but you're probably better off studying them yourself.

>>1490116
Thanks, this makes sense.

>>1489513

my eyes bled at the first sentence