https://preview.redd.it/19cls8e12uge1.png?width=675&format=png&auto=webp&s=d4bd5b1b670e06c0f409296a3a8849582ee3846b

https://www.tiktok.com/t/ZT26G4KMf/ This looks insane and I was wondering how it worked

Since Gravitons have not been found in 60 years of particle accelerators, it is time to search for an alternative. This is a highly speculative assumption, thought to the end.
The result surprisingly, fits to some today still unexplained cosmic phenomena

https://zenodo.org/records/14783621

A Jewish physicist (Gerald Schroeder) with a PhD in nuclear physics and earth and planetary sciences wrote it and it regards the age of the universe according to science and breaks down how the short description of creation in Genesis actually fits the finding that Earth is about 4.5 billion years, because time changes relative to the size of the soace it happens in.

Would be cool to get another physicist to read through it - it sounds viable to me but i am not an educated physicist so I don’t think of myself as a good judge of something written by a person with a PhD in physics. Would be nice to have a completely non-biased view upon it (that means not letting one’s own emotions and beliefs cloud any judgement but just read it from a physics point of view). :)

Link to the article: http://geraldschroeder.com/AgeUniverse.aspx

I had a dream, wrote a paper. Then, developed a simulation. Am I on to something?

I've done a quick animation which shows how the wavefronts of incoming light from a faraway galaxy behave in the LCDM model. I'm quite pleased as it turned out to be nice visual and simple way to illustrate cosmological redshift and horizons.

For example, for the distance I have set (20 Glyrs comoving distance) the galaxy is never inside the Hubble sphere (i.e. it is always receding from us faster than c), but you can see from the animation how light from it is still able to reach us due the rapid expansion of the Hubble sphere in the early universe.

https://www.desmos.com/calculator/upaj2z8qqy

Hey everyone, I am a physics major at a large university, sophomore. I am currently taking modern physics + lab, but I don’t feel smart enough for the major. I feel like my peers are all very intelligent, and I just don’t feel comparable. I have always been called smart and always breezed through classes, and physics is what i want to do. However, come tests and quizzes and i just don’t succeed. I have never been good at studying, so I have wondered if this is the issue.

If anyone has any good ideas regarding studying or how you study for physics exams please let me know. I’ve never had trouble with math since i know what kind of problems I need, and I just use the formulas. For physics, it can be a problem that i’ve never even seen something similar to and I’m supposed to click together how to solve it.

I don’t know what the problem is, but I’d do anything to fix it, or am I really just not smart enough to do this? Thank you all.

I’m working on putting together a Compton Scattering experiment for my university in the US. Does anyone know where I can purchase a Cs-137 gamma source between 0.1 to 1 milli-Curie? I think I need it to be pretty compact to make a collimated beam. (Edit: autocompleted to million but wanted to write milli)

Basically as title says. I’m looking to get into cosplay and my nontypical mind wants to plans things out completely. I’m interested in small pieces which will become stiff when held in tension. If you know a 3D software that’s cheap with tension and gravity that would be very helpful.

I need to learn thermodynamics by myself from the beginning because my courses were awful.

What are the best, preferably modern, books about thermodynamics for physicists? i.e. no Çengel and engineering stuff.

Also I'm in my senior year so almost any difficulty is ok.

I browsed the net for a bit and im still unsure. Are there rules about this?

Hey y'all.

Does anyone know of any resources (e.g., authors on medium, or some magazines, podcasts, communities) where knowledgeable people discuss about physics in general? Like the history of physics or some weird things about scientists that u wouldn't know unless you really went into them or something about some modern theories?

Where do you guys get your "general information" from?

Hey everybody,

This is going to sound ridiculous I'm sure, but it has been bothering me and I need an answer.

So my cat jumps up onto a particular table many times a day. One fluid motion, very majestic. Last week I had placed a large box on that table. Shortly after, my cat went to do his usual jump, but mid flight, he noticed the box was in his way and stopped himself.

Fucking how. Please

Hi everyone. I’ve been reading some physics books by Jim al-Khalili (the world according to physics, paradox’s, quantum a guide for the perplex). Are there any there other books to read that people with casual interest should read that they would find fascinating?

What have you found most helpful when learning physics, especially for beginners/undergrads?

Are there certain lecture series online that are particularly good, and what resources do you wish you had besides watching videos/reading textbooks?

(For context, I'm working on a project to make learning more effective and accessible. It's awesome that there's so much good stuff out there, but I think only watching videos isn't enough to fully learn. We're making practice problems, summaries, and a way to get personalized feedback from your answers.)

Curious what else you guys think might be helpful! Maybe a particular style of problems or some community aspect? And what courses to add next—we started with MIT 8.01, so maybe 8.02/8.03/other college lectures? I asked about physics YouTubers a while ago and you guys had some great recs—would some of those be helpful for this context too?

On not very knowledgeable about this, which is why i ask you smart people.

All dishes point to the equator, so wouldnt it be possible to get the longitude of the place by looking at the angle the dish is pointed? The more up to the sky, the closer to the equator?

What I mean is: can the laws be written in code or / and algorithms; are they computable? And if they can, what does this tell us about nature?

Are there attempts to make this happen?

Hi guys! Since this year is the international year of quantum science and technology, I would like to dedicate some time and expand my knowledge in that direction.

I have decided that I will try to red the original papers from the beginning of the 20th century about the topic.

I would like you to suggest me some papers you think are very important in the field of quantum for scientific or historical reasons (very broadly intended - from quantum information to quantum materials, from foundations to quantum Field Theory, etc).

The paper ideally should contain some concepts or idea that advanced the field or revolutionised it. You can also lost other resources or personal preferences.

Thank you in advance!

I was watching 3b1b's video about differential equations and I saw it there, what does phi do here I am genuinely shocked I thought it didn't do much in maths.

Hi, people, got a question here. Today I have visited a particle collider in my home country, and some information given by a physicist working there rose some questions.

He was explaining how plasma based accelerators work, and he explained there are two beams of electrons being shot one after the other, the second of which is accelerated by and electric field. He asked why, despite this, the second beam will never reach the first, and than argued that, since the electrons move almost at the speed of light, because of the expanded form of the mass-energy equation in special relaivity, their speed does not change at all, they just become more energetic.

I would have thought that, because of relativity, the actual acceleration thorugh space would have been very small (basically negligiable), and the electron would have acquired a lot of energy. Considering that the time component of the 4-momentum tensor is gamma times rest E over c, I may have phrased it as "most of the acceleration is in the time component of the 4-momentum"; the actual difference in the space component can be derived from the expanded form of the famous E equals m c squared equation.

But, as u can see, this is very different from what he said. I asked the teacher I was there with, and she told me she found the explaination given to us weird at the very least. We went back to the guy, and he told us that he was very happy to see we were trying to figure it out on our own, and that he had no intention to give us any info about it at all.

He felt like a competent person, and I have trouble thinking he might have been wrong, but I can hardly make sense of his thesis. I also kinda feel like it doesn't work in the classical limit; there, electrons accelerate for sure, and while it is absolutely reasonable that they accelerate less while speed increases, the fact that they stop accelerating at all before the speed is equal to c is just hard to concive.

Note: by speed I mean speed thorugh space, and so did the guy; i know that total speed through spacetime is costant, and equal to c.

This is a thread dedicated to collating and collecting all of the great recommendations for textbooks, online lecture series, documentaries and other resources that are frequently made/requested on /r/Physics.

If you're in need of something to supplement your understanding, please feel welcome to ask in the comments.

Similarly, if you know of some amazing resource you would like to share, you're welcome to post it in the comments.

Aside from the engineering impossibility, my biggest issue with Dyson spheres is that they would have major trouble cooling themselves. They should transfer some of the incoming energy into useful work but the rest would have to be radiated away, because of the 2nd law of thermodynamics. For efficient radiation the sphere would need to be hot as hell, or super large.

So, a star radiates energy as 4 * PI * Rs^(2) * k * Ts^(4).

If the Dyson sphere is to radiate that energy away it needs to do 4 * PI * Rd^(2) * k * Td^(4).

Equalling the two means the temperature, at which the sphere must operate is Td = (Rs / Rd)^(1/2) * Ts.

Now, assuming that the 2e8 km size of the sphere is its radius and that, in the episode, the star inside the sphere was like our Sun: radius Rd = 7e5 km and surface temp Ts = 5,7e3 K, then:

Td = 0.06 * 5700 K = 337 K

That's about 64°C (147°F for my US friends). That's bit warm, but if we also say that we can constantly convert some of the incoming energy into work, then that temperature could go down to reasonable levels.

I believe this could be the motivation behind choosing the sphere to be as large as it was.

And why is it always the theorists who do this ?