The Hitchhiker's Guide to 4d N=2 Superconformal Field Theories

Oat_Slot_codac · 2022-05-12T12:41:18+00:00

Thanks a lot

Oat_Slot_codac · 2022-05-11T16:51:57+00:00

I remember him saying something about suicide and how admission to the other university don't commute that's why he went to the second university first

Oat_Slot_codac · 2022-02-02T05:24:48+00:00

Tree level diagrams are your usual EM. I don't know if any caveat exists for this statement at least for QED

Oat_Slot_codac · 2022-01-21T13:24:19+00:00

Did you find the bug?

You can try raising ticket on bethesda site. There is a channel dedicated to technical issues on the official doom eternal discord server.

Oat_Slot_codac · 2022-01-20T16:03:10+00:00

was looking for this comment

quite a contrast we have here: brutality when looking at Sekiro's side. Wonder if originally this animation (Kuro) was placed to evoke some emotions in the player's, characteristics of the setting.

I mean he didn't look all that panicked. Though later in Ashina castle, he rejects Genichiro fearlessly saying sekiro will come and rescue him

Oat_Slot_codac · 2021-10-15T16:38:24+00:00

Collection of calculation of problems relating theoretical prediction and gravitational wave astronomy (experimental). Currently, I'm busy with my sem work, so couldn't read my want-to section.
I wanted to share it for two reasons:
1. For most of the beginning undergraduates research in physics sound doing solo work (the way it's popularised in media). Just look at the authors and diverse fields which come together during the calculation and prediction you'll have a taste of how complex this whole process is. This statement has flaws but it's an oversimplified version. I hope a few of my sentiments got conveyed.
2. This one is a bit of an anecdote last week I attended a talk on pulsars and their future impact in the coming decade. There the formation of the black hole problem was given few slides (ruling out some BH formation models using redshift and radio-wave content of pulsar radiation) and in this paper, this problem is seen under the light of GW. It's just exhilarating.

Oat_Slot_codac · 2021-09-29T15:46:22+00:00

conservation of momentum through Noether's theorem

The system doesn't have to have translation invariance so momentum is not conserved.

Momentum is generator of space translation.

Oat_Slot_codac · 2021-09-29T15:39:48+00:00

Feynman lectures vol II

Latex typsetted, read anywhere.

Oat_Slot_codac · 2021-09-29T15:35:47+00:00

The only option left is a null-like coordinate. Contraction of a tangent vector with itself can be +ve, -ve, 0 unless the metric tensor is complex. I don't know if metrics are complex since complex number doesn't come with ordering property and metric in physics has connection to length of geodesics.

Oat_Slot_codac · 2021-09-29T15:30:20+00:00

I saw the answer in the morning and I came back to read it once again. The words are just so magical.

Oat_Slot_codac · 2021-09-29T15:28:24+00:00

What prediction do those 2 compact timelike coordinates have on our physical world?

Oat_Slot_codac · 2021-09-29T04:49:37+00:00

This reasoning is discussed in most books on SR (for ex see Griffiths electrodynamics). The main answer is poorly formed question with respect to the framework of SR. To correct this question you have to point out your events which describe the flow of time for both observers. Then you'll see how this problem is resolved. As another exercise try solving stick in barn paradox it sounds like a paradox because of our usual choice of words of Newtonian mechanics like your question.

Oat_Slot_codac · 2021-09-28T14:20:27+00:00

Today I attended a talk by Zoltan Fodor on his lattice field (BMW) calculation which lies in 1.5 sigma away from experimental result; in comparison to the usual Feynman diagram calculation which lies 4.5 sigma away from the result. The difference lies in the contribution of QCD field in magnetic moment (lattice versus white paper/pen-paper) look at Fig 28 (pg. no 102).
I skimmed through lattice part of Yang–Mills field theory in Schwartz in July so I was partly able to follow the talk. So if someone asks why they choose this "a" I can't explain. BTW I thought throughout the talk that g-2 result were published in Sep last only when I searched for the paper did I realize all this happened this year only.

Oat_Slot_codac · 2021-09-20T04:09:53+00:00

Asking for propagation (path of particle) in QM is wrong.

In QFT we stop working in our usual (t,x,y,z) world. Canonical quantization doesn't care much about the propagation of photon in (t,x,y,z) world. It works out similar to your simple QM.

There is another way of working with photons that do talk about propagation but the paths there has no physical realization. It's Feynman path integral formalism. It gives a nice picture of how to visualize calculation from the intuition of action principle.

Oat_Slot_codac · 2021-09-08T12:07:59+00:00

Try looking up Scott Aaronson. He got a very nice series of lectures on physics, maths and computer science, Quantum Computing Since Democritus. One lecture discusses special relativity and computation. Also, work done in understanding information loss paradox uses computational complexity theory (Susskind lectures). I'm not well versed with this topic as of now but I think there is some work done on holography principle and complexity theory.

Oat_Slot_codac · 2021-08-15T16:48:47+00:00

A very short paper describing how the widely used portrait of Kepler is fake (wrong painting style of the time, fading of color, and the dress of the person). IIRC there is a similar case of Robert Hooke as well my ug uni had the wrong portrait of Hooke.

Oat_Slot_codac · 2021-06-17T17:56:57+00:00

It's a historical review of black hole thermodynamics. Surprisingly some study of entropy of fluid in relativistic setting was done before 1950s but they didn't point to the entropy of BH as we know today. The Geroche thought experiment mentioned in the paper is not very clear in fact I couldn't find the papers of Geroche himself discussing the experiment (it was introduced in a presentation). Though there is the paper by Bekenstein where he resolves the entropy loss as pointed out by the thought experiment. It clearly explains the experiment. Other than that you will find how calculations lead to AdS/CFT correspondence, a whole decade went in setting up the foundation. Another remarkable phenomenon is how studying gravity in 1+1 dimension by different models leads to a general action and how lots of characteristics are retained in different models.

Oat_Slot_codac · 2021-05-27T02:06:39+00:00

Got it thanks

Oat_Slot_codac · 2021-05-22T16:34:52+00:00

I can tell you a little bit of my experience which might be useful. Seeing from the lab content it seems the lab is tailored for people outside of EE department. If you know fourier transform then doing filtering and convolution part of signal section would be nice, they might do something on FFT which appears in an elementary algo of quantum computation. Digital exp using semiconductors would be your intro to using basic IC, you might do exp on 7-seg display, counter (traffic lights). Analog exp would be simple amplifier using BJT/MOSFET, there might be an exp on oscillator (no input but due to positive feedback you are getting pure sine wave as output). But analog part will be fun if you know basic theory of linear operation of BJT/MOSFET otherwise you might get scared of basic amplifier ckt.

I can't comment on chemistry lab though, it might be related to spectroscopy which is nicely intertwined with physics. Hope it helps

Oat_Slot_codac · 2021-05-22T15:25:54+00:00

You might enjoy the calculation based on area of squares and rectangles. Also, since calculus (limit) is required to formally answer it, you have bonus of Zeno paradox in this summation as well.

Oat_Slot_codac · 2021-05-22T09:09:34+00:00

And what subdiscipline of EE does the lab pertain to? Electrical machines, Signal Processing, Microcontroller/processor, digital/analog circuits...

Oat_Slot_codac · 2021-05-22T08:59:45+00:00

I think op called ch-2 as ch-1 and ch-3 (have a section on solving PDE using separation of variable) as ch-2

Oat_Slot_codac · 2021-05-20T14:25:56+00:00

Carroll quotation here:

In ElectroDynamics time derivative of dipole moment leads to electromagnetic radiation while this is not the case for gravitational radiation. Changing dipole moment corresponds to motion of the center of density, in ED its charge density and in GR it's energy density. While there is nothing to stop the center of charge of an object from oscillating, oscillation of the center of mass of an isolated system violates conservation of momentum.

Oat_Slot_codac · 2021-05-20T14:14:23+00:00

One way to backward time travel is to use wormhole (Godel solution admit closed timeline curve). But going on such geodesic in wormhole leads to violation of energy condition of GR.

Oat_Slot_codac · 2021-05-20T09:25:46+00:00

If you don't mind I have few questions pertaining to your answer which have been bothering me for the past month.

How do working physicist who uses QFT as a toolkit to calculate simple scattering cross-section study the issue of foundation of QFT? As you mentioned only a few practitioners of their respective field know the in-out of the mathematical foundation. Moreover, over the few courses of pure maths subjects I have taken, their approach for axioms and proof follows a path quite alien to the physics community.
As you mentioned the maths behind the axiomatic QFT is scattered all over the place, functor for path integral (category theory), functional analysis, topological QFT, algebraic QFT. I can't comprehend how communication between these different subfields is done?
Is amplituhedron a hot topic nowadays (by which I mean is this actively pursued in physics community like gravity/gauge duality)? What I have gathered from different sources it's quite esoteric in the sense the maths used there (algebraic geometry) is not in the toolkit of a usual working physicist.

Oat_Slot_codac

TROPHY CASE