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/sci/ - Science & Math

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8852844 No.8852844 [Reply] [Original]

>photons have no mass but they have momentum
>physicists will literally defend this

>> No.8852851
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8852851

>>8852844
Low quality bait

>> No.8852875

>>8852844
https://en.wikipedia.org/wiki/Energy%E2%80%93momentum_relation

https://youtu.be/JqNg819PiZY?t=40m

>> No.8852900

Didn't expect to find mOE here lmao

>> No.8852959

Isn't a photon a process, rather than an object with mass. The underlying matter where this process happens has mass. This process can be said to have the momentum pertaining from the underlying system that sustains it.

>> No.8852979

>>8852844

Haven't played CS in ages.

>> No.8852989

>>8852844
Photons have relative mass, idiot

>> No.8853184

E=hf E=mc^2

hf=mc^2
m=(hf)/c^2

>> No.8853194
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8853194

>>8853184
>E=mc^2
Brainlet thinks that E is only mc^2

>> No.8853199

>>8853184
>E=mc^2
oh wow. Just stop please.

>> No.8853204

>>8853184
This is what happens when highschoolers get on this board.

>> No.8853255

>>8853194
>>8853199
>>8853204
Obvious samefagging.

>> No.8853264
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8853264

well not me buddy

>> No.8854173

>>8852844
We say it has no mass simply because it's always moving and we can't trap one and put it on a weighing scale

>> No.8855579

>>8853264
>>8853184
>tfw too retarded to realize e=mc^2 at low speeds

>> No.8855608

>>8852844
Photons without momentum would violate energy-momentum conservation.

You can create a model where they don't, but then weird things happen.

Photons also have angular momentum.

>> No.8855617

>>8854173
>if I don't seez it it don't realz

>> No.8855622

>>8853184
That's the enery at rest, you faggot. Photons are not at rest

>> No.8855625

They do have mass but its so small its somewhat pointless to talk about

>> No.8855720

Wait WTF!? E doesn't equal mc2??

>> No.8855784
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8855784

>>8855720
>>8853184
>e=mc^2

>> No.8855790

>>8852844

Physicists created momentum, they can do whatever they want with it.

>> No.8855816

>>8855579
being too retarded to use the proper formulas so you dont acrew error for no reason other than you being a stupid ape

>> No.8855895

>>8855784

Massive physics brainlet here, gonna take a crack at this.

Kinetic energy is equal to the initial particle mass * SOL^2 * gamma ray released -1.

Or: kinetic energy is equal to initial particle mass *SOL^2 per the sqrt of (1 - actual velocity^2/SOL^2) - m*SOL^2.

So it's stating that the kinetic energy of a particle is not a result of its mass? That it is related to the difference between the energy in a vacuum and the energy in a vacuum fraction of a refraction index?

Would that mean that the refraction index was <1 and that the medium allowed faster than light speed?

>> No.8855922

>>8855895
WRONG lol.
You can't just assume gamma means the same thing in relativity as it does in optics. Simple algebra shows that
gamma = 1/sqrt (1-v^2/c^2).

This is an expression for the relativistic kinetic energy of an object with mass m.

In relativity, you often see that the total energy of a particle is its rest mass + kinetic energy.

Solving for kinetic energy, you see that it is the total energy - rest mass, which is what is shown in the picture.

>> No.8855934

>>8855895
gamma ray? its relativistic Lorentz factor. its just a more accurate way of expressing energies. As velocity increases, so does the mass of the object which is why it takes exponentially more energy to accelerate. the numerator cant be >1 or <0 because youd break the universe with infinate energy.

>> No.8855948

>>8855922

Yeah I didn't think I was gonna get to far there.

>>8855934

The increase in mass makes sense.


How does one calculate the actual resting mass of a particle though, if everything is in motion? Or is that the relativity part?

>> No.8855961

>>8855948
it really doesnt matter at such low velocities because you can sort of assume the inertial frame. for actual scientist who measure the rest mass of elements, they use far more complex things such as trapping particles in high electromagnetic flux to stabilize them.

>> No.8855970

>>8855961
>>8855948
i should elaborate more but this article does a good job of explaining mass spectroscopy.
https://www.google.com/amp/amp.livescience.com/20581-weigh-atom.html

>> No.8855978

>>8855970

I'm familiar with mass spec actually, it's the relativity physics that throw me off.

Thanks for the formula explanation

>> No.8856082

>>8852989
What does that even mean?

>> No.8856099

Momentum in classical and relativistic mechanics is treated in quite a different way. In relativity there is a 4 component vector that describes it. The norm of the vector is equal to the mass in the rest frame. The fact that the photon 4-momentum is zero means that there is no inertial frame where it can stay firm. By the way it carries energy, and in reference frame where it is in motion, this energy is equal to its momentum. The norm in a Minkowski space is zero for all the things moving at the speed of light. Furthermore the minkowski space was created to give the speed of light as an invariant for every reference frame.

>> No.8856226

> photons
> Physicists will defend this

>> No.8856236

physicist are mindless cultist. What else is new