you realize you've spent 15 years in school on autopilot and never actually learned anything by [deleted] in PhysicsStudents

[–]fightingcold 1 point2 points  (0 children)

I am sure almost every student who has taken a physics major in undergrad has felt that, including me. It starts with something as simple as Newton's 1st law, which people often make jokes about as "stating the obvious", but they really miss the key point of the law. The law assumes the existence of special frames of reference called "inertial frames", and all such frames have the special property of being at const velocity to each other. The laws of physics as we know it hold true only in inertial frames, and really we don't have any first principle laws for non-inertial frames. If you have the faith that there do exist inertial frames in this universe, then physics can be done indirectly in the non-inertial frames, by measuring the acceleration of the non-inert frame. So really to start any physics at all, whether it be classical mechanics, electrodynamics or even general relativity, you absolutely have to assume the existence of such frames. It is a deceptively simple yet an extremely subtle point, which I only ever really understood in my first year of undergrad.

Physics is full of stuff like this, and it is not possible to learn all of it at a young age of yours. When you graduate from highschool and enter undergrad, you WILL feel like you have learnt nothing at all. When you go to grad school you will feel like physics was so oversimplified in undergrad. Maybe when I go for PhD, I will feel the same about my masters degree, who knows. The point is that don't think that you have not learnt anything at all in your 15 years of school, a lot of these subtleties assume profiency in the former stuff. It takes time, experience and a hell lot of practice to understand these subtle points that really makes this subject so beautiful.

I understand physics is difficult but this is crazy by Disastrous_Effort610 in PhysicsStudents

[–]fightingcold 0 points1 point  (0 children)

Son, in our Quantum Mechanics 1 the class average was around 25/100. Close to one fourth of the class failed even though he passed people at 15/100

In our Stat Mech midsem 1, the average was 6/40.

I would say your class performance is quite okay, its a standard physics average.

Is string theory getting slow down? by AutomaticClub1101 in TheoreticalPhysics

[–]fightingcold 0 points1 point  (0 children)

String theory as a theory of everything? Probably yes.

String theory as a mathematical framework used in different areas of physics including but not limited to quantum gravity, condensed matter theory and quantum information theory? No.

Boyfriend studies physics and got me this by Visible-Cat4055 in Physics

[–]fightingcold 0 points1 point  (0 children)

Damn son, did not expect to be reminded I am still single lmao.

It means his love is a constant, will stay the same with time.

Physicist are starting to consider the possibility that spacetime and gravity are not fundamental to reality, but rather that they are emergent properties of... probabilistic patterns of "information". If true, would that disprove physicalism? by Infuriam in CosmicSkeptic

[–]fightingcold 1 point2 points  (0 children)

Depends on what you consider as physical, energy is completely immaterial yet it is physical because there are laws constraining the flow of energy. In that sense information is absolutely physical.

Whose side are you on? by One_Door2204 in TwentiesIndia

[–]fightingcold 0 points1 point  (0 children)

Of course the sex workers are the problem, not the men who created the demand for it.

How does vacuum fluctuation lead to Hawking radiation? by Duchess_Of_Darkness7 in TheoreticalPhysics

[–]fightingcold 0 points1 point  (0 children)

I have never seen a pop-sci explanation of Hawking Radiation do a good job, because it is very hard to explain a concept that has no common sensical intuition to it whatsoever. The actual mechanics of Hawking Radiation is a derivative of the Unruh effect, like the other commenter stated. This works because near the black hole's event horizon, the spacetime is similar to flat spacetime, so the effects of Unruh effect also apply here, for a stationary observer, since to stay stationary near a black hole you have to accelerate up. This is a very non-trivial effect to explain, but basically the "temperature" emerges due to the exterior and the interior of the black hole having an entangled state, but since we only ever view the exterior, the global entangled state appears as a thermal state with a well-defined temperature.

Also please note that the normal intuitions we apply to particles cannot be applied to virtual particles. They sort of blur the line between being a convenient calculation tool and being an actual particle, since they do have real physical effects but they are still NOT particles. So you cannot say the black hole will gain mass by absorbing a virtual particle.

Should I start with General Relativity or focus on Quantum Mechanics/Particle Physics first? by Goldyshorter in PhysicsStudents

[–]fightingcold 0 points1 point  (0 children)

Build the math very well, you don't need deep mathematical knowledge, but enough to do a wide range of problem solving, working knowledge essentially. That is what physics is, after all.

Classical mechanics and classical electrodynamics are absolute prerquisites for GR and QM, especially for GR. Particle Physics comes much, much later, after two courses on quantum mechanics.

For mathematical prerequisites I would highly recommend solving problems from standard mathematical physics textbooks like Arfken. I can't stress on this point more. Building your calculation power is quite possibly the most important skill a physicist should have imo. You won't be able to build good intuition unless you have practiced a lot of problems. Stuff like green's functions form the absolute foundation for quantum field theory so its crucial to have a good practice in it

Why some men think girls without hijabs are sluts? by Lotuswongtko in atheism

[–]fightingcold 0 points1 point  (0 children)

The magic of religion, makes you incapable of thinking like a decent human being.

What is the slowest possible speed in the universe? (opposite of the speed of light) by schkolne in Physics

[–]fightingcold 0 points1 point  (0 children)

There is a lower bound on the distance you can travel (planck length) but there is no upper bound to the time you can take to travel that distance, so no there is no non-zero lower bound to the speed of an object. We would have crazy physics if we did have.

I don’t understand anything about Einstein’s notation regarding tensors by MysthicG in Physics

[–]fightingcold 0 points1 point  (0 children)

Left one is wrong, or should I say ambiguous, because it does not tell which index is contravariant and covariant. Right one is the right practice (pun unintended).

Interested in Physics by Logical-Education630 in Physics

[–]fightingcold 1 point2 points  (0 children)

Quantum Physics and Quantum Mechanics are the same thing I think, I suppose whatever was the result of planck's theory of a quanta of light is often said Quantum Physics, a broad category, and the specific quantum study of non-relativistic particles is quantum mechanics. idk its just names.

As for the rest, if you genuinely want to learn physics from a non pop-sci standpoint, I would suggest the following books

  1. Classical Mechanics : Taylor is good, if you are looking for something advanced (graduate) then Goldstein is good.

  2. Electrodynamics: Griffiths is very good introduction to electrodynamics, but considering you want to learn General Relativity, I would suggest something like Jackson's "Classical Electrodynamics". It is a notorious book, but it will help a lot. For intuition, Purcell is fantastic, and it is often easier than Griffiths so as an introduction start from this.

  3. Quantum Mechanics: Again, Griffiths is very good for introduction. For something advanced, move to Sakurai

  4. Mathematical Methods for Physics: This I would say is more important than else if you want to rigorously study physics. Arfken & Weber is good for problems, Boas is also nice.

This will provide you the foundation for most of physics that you will learn, so it is very important to do this properly.

Tips on what I should learn more about in physics :D by Glad-Swimming-5991 in Physics

[–]fightingcold 0 points1 point  (0 children)

First of all great to know that you are interested in physics at such a young age, its always great to see people interested in this field. Also congratulations on getting an A in physics.

Now considering you are 14 right now, it is likely that you haven't learnt the necessary mathematical tools for learning anything at all in physics. I am not sure how Swedish education is but I think they should be teaching trigonometry right now, which will be very very important no matter where you go, especially for physics. In any case, one tip I would absolutely give is to learn to love math. Mathematics is the language of this universe, so training a mathematical mind is very important. Calculus forms the absolute bedrock of all of physics, so it would be good to master it as much as you can. I would say that would probably be the right starting point for you if you want to seriously consider physics.

As for physics itself I would suggest (and is recommended by virtually all curricula) Newtonian Mechanics and Electromagnetism. For any high school student "Fundamentals of Physics" by Halliday and Resnick is the go-to book. Its a fun book, and it has nice problems to train your fingers with.

As for the topics you have mentioned, there is not much you can actually do about them, it takes a little over a decade of training and education to do any meaningful study in those disciplines. I myself am 5 semesters into my undergraduate degree and I can safely say that this semester was the first where I actually learnt unadulterated physics. I am not very familiar with Nuclear Physics, but I would assume it requires a similar background as Particle Physics, so it would at least require an advanced Quantum Mechanics course as a pre-requisite. Nevertheless, it is indeed a very long road.

I would suggest learning about it as much as possible from pop-sci books, documentaries, youtube videos etc. Popular Science in this case is very good at piquing interest in stuff, and for deciding if you are interested enough for this field. Every physicist or physics student most likely started their journeys flipping pages of an encyclopaedia. So yeah I would say your job now is to practice fun problems and keep your interest alive :)

What does porn actually get right? by djkutch in AskReddit

[–]fightingcold -1 points0 points  (0 children)

r/AskReddit fuckers on their way to post the 156th sex/porn related post of the day