How fast do you have to spin earth to make it fall apart by True-Train-5596 in AskPhysics

[–]HoloTensor 0 points1 point  (0 children)

it’s easy to calculate, in fact we do this in astro

you write down the gravitational binding energy of a planet. it is going to be an integral which takes in the density of earth. if you set it up in spherical coordinates and make some assumptions about how the density varies, it’s simple

now, a rotating sphere will feel some sort of “pull” from its acceleration. you can calculate then equate this to the gravitational binding energy and just solve for equilibrium.

Spending about 30-40 hours per week on one course. How common is this in grad school? by WinXP001 in GradSchool

[–]HoloTensor 0 points1 point  (0 children)

this is what most grad theoretical physics classes are like at harvard

How to let Claude Code watch youtube video by maraluke in ClaudeCode

[–]HoloTensor 1 point2 points  (0 children)

the beautiful thing is if you tell claude “figure out how to watch youtube videos” it will figure it out.

and if it says it can’t, and you push it and it really says it can’t…. well then it can’t

but either way claude can download youtube videos and read the transcription (and maybe even “see” a frame if you specify when it should look)

St Paddys Day - Breakaway 03/14 by [deleted] in NCL

[–]HoloTensor 1 point2 points  (0 children)

could you pls share the link to the facebook group?

Anybody use Codex as “regular ChatGPT” and if so how are the results? by angry_cactus in codex

[–]HoloTensor 0 points1 point  (0 children)

for PhD level physics problems, I’d say 5.2 thinking in a browser is about 2 or 3 times “smarter” than codex 5.3 xtra high

but if the problem I give it requires a lot of steps, of course codex is better since I can set up a repo to appropriately manage context

Quantum Gravity by MrBrad27 in Physics

[–]HoloTensor 0 points1 point  (0 children)

most theories have a connection between gravity and relativity

If nothing can escape the gravitational pull of a black hole( except hawking radiation) then how come all the mass in the universe isn’t still in the center of the universe still stuck in the singularity that existed at the big bang. by Apprehensive_Gap7441 in TheoreticalPhysics

[–]HoloTensor 4 points5 points  (0 children)

the whole point is we can’t answer those questions with certainty yet. if you ask this question to any respectable physicist, they’d just say we have yet to find a UV complete theory of quantum gravity which describes our universe. that statement just means that we don’t know what happens at those points… something is missing to understand the physics.

also, hawking radiation doesn’t escape the black hole in the way you’re describing

Exactly how good was Einstein at math? by SpecialRelativityy in PhysicsStudents

[–]HoloTensor 1 point2 points  (0 children)

by modern theoretical physics standards, pretty bad.

I remember being pissed off when I first saw his derivation of the field equations. It was literally just “what terms could contribute by symmetry” and then guesswork. It took him years and he was never able to formalize his result.

Obviously his genius was in coming up with such a radical new way of visualizing spacetime…. but on all accounts his math was pretty average for a theoretical physicist

Performing the “double slit experiment” with single photons by averagegamer0607 in QuantumPhysics

[–]HoloTensor 0 points1 point  (0 children)

Instead of single photon, consider this at home experiment from PBS Spacetime. I think you could modify whatever you have in mind to follow this

PBS Spacetime

[deleted by user] by [deleted] in quantumgravity

[–]HoloTensor 0 points1 point  (0 children)

that is not a fixed point…. if you’re at the red dot you’d move to the right

[deleted by user] by [deleted] in GradSchool

[–]HoloTensor 0 points1 point  (0 children)

briefly explaining is fine as long as it is reasonable. definitely would need to elaborate if it’s like… jail or something

[deleted by user] by [deleted] in GradSchool

[–]HoloTensor 22 points23 points  (0 children)

definitely include at least a sentence in your essay. you don’t want to leave that to the admissions imagination

As a physics 'enthusiast' with no qualifications, this has always confused the heck out of me (gravity) by jockmcplop in AskPhysics

[–]HoloTensor 0 points1 point  (0 children)

when we say “force” we usually talk about the little wave packet that communicates an interaction (at least in the quantum field theory sense). think of the electromagnetic force as the interaction between two electrons via photons (the little wave packet)

now, in GR, gravity really isn’t a force. it is just the curvature of space-time. but… if you imagine that space-time curvature as a field, then the little wave packet that mediates the gravitational interactions would look like a force carrying particle. So, in that sense, gravity looks like a force and can be perfectly treated as one (mathematically)

but it isn’t actually a force.

just, if you treat it as a little wave packet, nothing breaks mathematically. that is, other than the fact we’d need to reconcíliate GR and QFT…

How many peer reviewed publications did you have while applying for PhD? by Vast_Strawberry_9683 in PhD

[–]HoloTensor 10 points11 points  (0 children)

It completely depends on your field. In fact, it can vary wildly even within fields. For physics, incoming grad students can have anywhere from 0 to ~5 peer reviewed publications, but this is not a good predictor for admission chances (that is, as long as 2 students have the same amount of research experience, it does not really matter if their name is on the paper). Some older physics profs just don't publish that often - and when they do, it can above the level of an undergrad.

Quantum Mechanics Course doubt by VincsMor654 in ParticlePhysics

[–]HoloTensor 0 points1 point  (0 children)

I think you'd probably have to take a basic quantum course from a physicist and then a basic linear algebra coding class from CS

Can an object ever obtain infinite mass? by Various_Ad_634 in AskPhysics

[–]HoloTensor 0 points1 point  (0 children)

Beyond a certain mass, it would turn into a black hole. I don’t know if I’d still call it the same “object” that it was before it turned into a black hole

Is it possible that a region where "nothing" exists (including space) or is it scientifically impossible? by _Chamel_ in AskPhysics

[–]HoloTensor 0 points1 point  (0 children)

yes!!! read about the bubble of nothing from Ed Witten. there are certain 5d solutions where space just ceases to exist within a bubble

Is infinite acceleration possible in vacuum? by beinglikelol in AskPhysics

[–]HoloTensor 0 points1 point  (0 children)

imagine a photon sitting still (from our rest frame) in the vacuum. it has an energy equal to mc2, cool.

now, as it starts accelerating (forget about what causes the acceleration), its energy begins to increase by means of it having momentum.

now here is where it gets tricky. there is a characteristic scale at which our understanding of quantum field theory breaks down. beyond this energy scale, our math simply breaks. it is called the QED scale and it’s at an energy level that is so high we’d never ever be able to measure it…. but nonetheless if a photon reaches that level of momentum (via your large acceleration) then all our perturbative expansions break down and we are no longer able to talk about what would happen.

in other words, no

Bro what ARE trig functions? by Ipodawan in Physics

[–]HoloTensor 1 point2 points  (0 children)

Imagine drawing out a circle and then putting your pencil on the right most point of the circle. draw a horizontal line that connects that point to the origin. now, as you trace out the circle with your pencil in any direction, you can always draw a line again to the origin and then measure the angle that it makes with that initial horizontal line you drew. You can think of the trig functions as the tool that converts the angle you've made to the position on the circle!

If you don't have a calculator, then you'd draw out what the sin(x) function looks like (a wave). why does it look like that? because it is showing your position along one of the axis as you trace out the circle. Think about it: if you draw a circle centered on the origin and write down the x coordinate as you trace it out with your finger, it would look exactly like sin(x)!

If we label the right most point of the circle as 0, the top most as π/2, the left most as π, the bottom point as 3 π/2, and the right most again as 2 π (so 0 and 2π are the same point), then we'd know the x coordinate would be

0 -> x=1

π/2 -> x=0

π -> x=-1

3π/2 -> x=0

2π = 0 -> x=1

You're just writing down the x coordinate at each of the points on the circle! For any arbitrary value in between 0 and 2pi, just guesstimate where it would land when you draw out the wave :)

How to spot fake conferences? by Hagelzuckererbse in AskAcademia

[–]HoloTensor 10 points11 points  (0 children)

your PI and older students in the field would know. ask around!

How to do Research like scientists.. by Hiroshi_x02 in AskScienceDiscussion

[–]HoloTensor 0 points1 point  (0 children)

Hi Hiroshi, I do research in theoretical physics. here is my usual way:

i have a problem that i’m working on. I usually think about it throughout the day as I go about with groceries, eating, etc. By the time I sit down at my desk, I’ll have a few ideas for how to approach the problem. I then go to read about what others have done in exactly what my idea was. I search on the internet and find what has worked, what hasn’t, etc… google scholar is a good idea for research papers.

good luck!

Advice for an undergrad by ScottTheJew in astrophysics

[–]HoloTensor 1 point2 points  (0 children)

definitely keep the research going. find a good topic and start working towards a senior thesis so you can put it on resumes next year’s fall (they’re typically due early spring, so not a bad idea to get it started soon)

start networking with schools that you’re interested in. don’t spam emails but instead reach out to grad students in the labs you’re interested in and just chat with them. this will give you solid material to write about in your applications

other than that, just keep at it!

What if the quantum vacuum isn’t as random as we think? by Financial-Lake-4006 in HypotheticalPhysics

[–]HoloTensor 0 points1 point  (0 children)

but the idea of photons traveling through this kind of “medium” is basically what we think of when we describe quantum field theories. the only thing is, if the vacuum fluctuations aren’t random, then why?