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4:56 AM
@PM2Ring hi
 
 
2 hours later…
6:54 AM
Last night dream:
The dream involves the lab director inviting me to examine this object. As he stood next to me telling me about the background of this object, I held it for a few minutes, before it started to encase my hand. It takes effort to pull my hand back out again and then the object reverts to its usual octahedral structure.
The object is made of solid energy, which basically means that while it has a rest mass, it is literally a block of energy, thus $E=mc^2$ does not describe it. This also makes it semi tangible meaning there are certain times when you touch it, your hand move right though it as if there is nothing
$E=mc^2$ only describes how given a certain amount of energy or mass, it can be interconverted between each other. It does not mean rest mass is energy, meaning for an "intangible block of field" like this object here, the equation is inapplicable because here the field behaves as if it has rest mass
Or if you like, this object is a field with nonzero rest mass. In physics literature, such possibility was explored in the past in the context of the graviton, but such models have been ruled out to be viable
The Higgs boson is massive of 125 GeV, however I don't know enough quantum field theory to comment whether the notion of rest mass makes sense in describing the Higgs field
In particular, the Higgs boson also gains its mass from the Higgs mechanism, hence it is not true it starts massive and then give mass to other particles
 
7:34 AM
5
Q: Does field energy create rest mass in QFT theories?

Alan RomingerThe central importance of Higgs boson would be that the Higgs mechanism gives rest mass to fundamental particles. It seems like a very natural argument that fundamental particles need to be given rest mass by a field interaction because as something fundamental (or a perturbation in a field as i...

 
0
Q: Shouldn't there be a language translation technique on physics stack exchange?

UniqueAs we know that physics stack exchange is an international website so there must be language translation technique for non english speakers as they face problems to Express them freely.

 
7:49 AM
11
A: What is "mass" in particle physics?

Luboš MotlThe mass always means the same thing – but in different theories, one uses different equations and other tools to express the mass. Inertial mass $m$ is the quantity expressing "resistance of the object with respect to acceleration", i.e. the coefficient that enters Newton's $F=ma$. The gravitat...

and so a field with nonzero rest mass is just our usual quantum particle (bosons, fermions (or for 2D systems, anyons as well) whose associated field has a nonzero mass term
and according to these answers, the Higg's rest mass is an interaction term from the Higgs field arise from its nonzero vacuum expectation value
Thus we have many examples of fermion fields with nonzero rest mass, and for bosons, we have the W and Z bosons and their associated fields
 
If someone is drunk, and you pop a small hole in him with a pin to get some blood, and you try to fire up the blood like fuel, will the whole person burn in a chain reaction? (God, what questions am I asking...)
@Secret I dreamt about flying.
 
does blood even burn at all, it is mostly blood plasma which is mostly water
 
ya but there's alcohol in blood
 
if you have an alcohol concentration that high in the body that it can combust, you are already dead from acute ethanol poisoning
 
ah, k
Damn it was so cool flying in my dream...
Some day I'm gonna make flying (like superman) possible.
 
8:03 AM
well good luck with that, you might need some kind of anti gravity implant to make that work if you do not want to rely on transportation
and I don't think we can solve antigravity without quantum gravity
 
anti gravity implant? whats this?
Something you implant in the human that will resist gravity?
 
pretty much, it does not exist presently
 
I have an idea
 
It might possibly work by somehow having the wearer such that the metric tensor around him is flat spacetime, thus it cancels out the curvature of spacetime around the wearer so he does not need to follow geodesics of curved spacetime around him
I don't know how you can do that however, since anything we knew currently have negative gravitational potential
so you cannot really "uncurve" spacetime
 
I'll separate the eyes from the brain while still sending the information with RF to the brain. I'll tape the eyes to a drone and voila.
 
8:09 AM
that's not really flying, you just looking at the world via a video screen
 
I also don't know of any method that one can use to cloak a nonzero stress energy tensor in some region of spacetime, since any material used to construct that cloak will have nonzero stress energy tensor thus it will curve spacetime in its immediate vicinity
 
What's metric sensor, flat spacetime, curvature of spacetime around wearer, geodesics of curved spacetime?
@Secret I don't have knowledge of GR, QM or SR
 
oops
 
Maybe very very basic
 
8:12 AM
I always thought you have since you, Johnrennie and Acuriousmind are often seen discussing questions around these, sometimes gone very technical
my apologies
Metric tensor is a mathematical object that tells you how to measure distances between two events in spacetime.
It is related by the einstein field equation (which basically tells you how spacetime is curved when you have some energy momentum in it) to the stress energy tensor (a mathematical object that tries to capture the distribution of mass, momentum and energy in a region
The equation looks something like this:
 
@NovaliumCompany are you a physicist or done any specialization in physics
 
@yuvrajsingh 17 y/o high school student who gets interested sometimes
 
$$R_{\mu\nu}-\frac{1}{2}Rg_{\mu\nu}+\Lambda g_{\mu\nu} = \frac{8\pi G}{c^4}T_{\mu\nu}$$
 
@Secret Thanks, but I better get some knowledge in those fields and then get back
 
ok I will stop here
 
8:18 AM
From which part of the world @NovaliumCompany
 
@yuvrajsingh Bulgaria
 
Aah I am just 18 y/o so from India @NovaliumCompany
 
@yuvrajsingh cool
 
How is going on what kind of subject you have in your current class @NovaliumCompany
 
@yuvrajsingh Sorry?
 
8:32 AM
I mean your syllabus of this year in physics @NovaliumCompany
 
@yuvrajsingh Boring... I know it all up to the end of high school
 
 
2 hours later…
10:52 AM
is photon also have de broglie wavelength
 
 
4 hours later…
rob
2:51 PM
@yuvrajsingh Historically I think the association went the other way. It was the association between a photon's wavelength, energy, and momentum (as defined in relativity) which inspired de Broglie to assign a wavelength lambda = h/p to the electron.
So the relationship is the same, but for protons it predates de Broglie.
 
Is "eigenline" a word?
I'm trying to write in an answer that the worldline of light is an "eigenline" of the Lorentz transformation, i.e. parameterized by eigenvectors
Then again I guess we can add "eigen-" to anything these days
 
3:22 PM
@JohnRennie hi
 
@yuvrajsingh hi
 
Where were you @JohnRennie
 
@yuvrajsingh I drove home from my mother's house this morning.
 
@Secret it looks like a door to me XD
 
Oh I see, actual sir my question is on, is photon have de broglie wavelength, it has energy, it has frequency, then it should have momentum, like rob said it was because of association @JohnRennie
 
3:28 PM
I've never seen my face.
 
@yuvrajsingh photons do have momentum.
 
What about wave length @JohnRennie
 
@yuvrajsingh the de Broglie wavelength of a photon is just the wavelength of the light
e.g. 500nm light is built of photons with a de Broglie wavelength of 500nm.
 
@JohnRennie they are free, a photon hitting them will scatter elastically, or might give up part of its energy to the electron and go away with a smaller energy/frequency (E=hνE=hν).
Electrons can be free
 
3:51 PM
@NovaliumCompany Don't you trust mirrors? If you close one eye, you may be able to see the side of your nose.
 
Hi who could point me to some clear material on Matsubara summations?
I'm dealing with a Wick rotated weighting function
That is pi periodic
Does everything just rotate along with the plane?
So for example The weighting function $+ f'(z) / (1+exp(-i*f(z)))$, controls the upper half plane Im[f(z)]>0?
Sorry correction: not pi periodic
Rather it is pi mod 2 pi
For all the "frequencies" I'm considering
 
 
2 hours later…
6:15 PM
I just watched The Butterfly Effect
God, what a movie...
How is it possible for someone to come up with such a plot...
 
Have you seen Predestination? I find that's like 20x more mind bending (mind you I haven't seen Butterfly Effect in like 10 years)
 
@JMac I've seen Predestination and is also pretty amazing, but The Butterfly Effect really twists your cognition.
I'm still figuring some stuff out about the movie
If there has been cases of a baby hanging itself in the womb, we know what's going on.
 
 
3 hours later…
9:11 PM
-2
Q: I know I'm 'right' about something non-mainstream and 'crackpot', what are the options for me here?

CorrectCrackpot I have a question about my Physics Stack Exchange post: I know I'm right about something that the mainstream is wrong about. How to get heard out without publishing in a journal? Pretty much as the linked question states, I have a big new theory (yes, theory, with evidence). Yes, there's so...

 
psa
9:46 PM
If you have some photons with some measurable energy (and associated energy) in one frame, can you ever find a frame where the total momentum from the two photons is zero (the centre of momentum frame)?
 
rob
10:32 PM
@psa Yes. For example, positronium at rest decays into back-to-back photons.
 
psa
@rob en.wikipedia.org/wiki/… is this article wrong then?
"Systems that have nonzero energy but zero rest mass (such as photons moving in a single direction, or equivalently, plane electromagnetic waves) do not have COM frames, because there is no frame in which they have zero net momentum."
 
rob
10:59 PM
@psa The quoted sentence is poorly phrased. It's correct that a single photon doesn't have a rest frame.
 
psa
@rob what's the difference between not having a rest frame and not having a COM frame?
It's because we're talking about two photons - i.e. there's some frame where their net momentum/energy is zero, but there's no frame where the photons individually have zero momentum/energy?
 
rob
@psa Usually, those two terms mean the same thing.
 
psa
right
that's what I'm a bit confused about
 
rob
@psa There is a frame where back-to-back photons have no momentum, but not a frame where they have zero energy. Vectors vs scalar.
I can imagine an argument about whether such a system actually has a "rest mass" $m^2=E^2-p^2$. It seems like an argument about vocabulary without much physics content.
A single photon never has $p=0$.
 

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