# Search results for query: *

1. ### How does Python tell that an integer is actually an integer?

I think Python determines types at runtime unlike other languages like C++.
2. ### B Regarding Contravarient Vector Transformations

Ahh ok. I think I get it now. Thanks
3. ### B Regarding Contravarient Vector Transformations

The ## \bar{x^1} ## grid squares are twice as big as the ## x^1 ## grid squares so the ## \bar{V^1} ## component should be half as much to compensate for that (contravarient), right? Okay. I found online that you get a transformation matrix as an answer but how do I use that to get the...
4. ### B Regarding Contravarient Vector Transformations

Okay, now I think I understand this. I just have one question. Above I wrote ## \bar{x}^1 = 2x^1, \bar{x}^2 = 2x^2 ## Now if I use the formula for calculating the components of the vector ## V(1, 2) ## (which uses ## x^1 ## and ## x^2 ## coordinates) in ## \bar{x}^1 ## and ## \bar{x}^2 ##...
5. ### B Regarding Contravarient Vector Transformations

Thank you so much this really cleared things up.
6. ### B Regarding Contravarient Vector Transformations

Ahh ok. Thank you.
7. ### B Regarding Contravarient Vector Transformations

Let's say I have coordinate system ## x^n = (x^1, x^2) ## and another ## x'^m = (2x^1, 2x^2) ## . I know this isn't the best example. Let's say I have a vector ## V=(1,2) ## Now according to the formula: ## V'^m = /frac{/partial x'^m}{/partial x^n} V^n ## Now if I'm looking for the first...

Okay, thanks
9. ### B Regarding Contravarient Vector Transformations

@PeroK just out of curiosity, what is this specific formula called? I'd like to learn more and I couldn't find exactly what I was looking for.
10. ### B Regarding Contravarient Vector Transformations

Okay, thanks a lot for your help on this. I bought a textbook on QFT and this is one of the things I need to know. I'm 16 so buying the textbook was a bit ambitious looking back but I'm still going to give it a shot. Thanks for the link btw. Have a nice day :D
11. ### B Regarding Contravarient Vector Transformations

@PeroK ok, so after scratching my head for a couple of hours I think I get it now. Is this correct? Suppose we have a coordinate system ## x^n = (x^1, x^2, x^3) ## and another ## \bar{x^m} = (x^1 * sin(x^2) * cos(x^3), x^1 * sin(x^2) * sin(x^3), x^1 * cos(x^3)) ## . As you can see, ##...
12. ### B Regarding Contravarient Vector Transformations

I'm trying to learn this using the internet, so sadly no textbook. But thanks for your explanations, I think I have a better understanding now.
13. ### B Regarding Contravarient Vector Transformations

Okay. Sorry, but this is all very new to me. So let's assume that I have a vector ##V## in the ## x^m ## frame of reference and it's components are: ## \left( 1, 2, 3 \right) ## With the basis vector ## \hat{i} , \hat{j} ,\hat{k} ## one can write ## V = 1 * \hat{i}, 2 * \hat{j}, 3 * \hat{k}...
14. ### B Regarding Contravarient Vector Transformations

Ah ok. But if I'm trying to convert a Vector from one reference frame to another, how can I know the component of the vector in the new reference frame. Isnt that what I'm calculating? And what is the difference between V^m and x^m ?
15. ### B Regarding Contravarient Vector Transformations

Hello, I have a question regarding the contravarient transformation of vectors. So the formula: V'n = dx'n / dxm Vm So in words, the nth basis vector in the ' frame of reference over the mth (where m is the summation term) basis vector in the original frame of reference times the mth...
16. ### B Regarding Time Dilation

Ahh ok thanks for clearing that up
17. ### B Regarding Time Dilation

Ok thanks for clearing that up.
18. ### B Regarding Time Dilation

Ah ok. thanks
19. ### B Regarding Time Dilation

If time slows down for an observer traveling at some speed relative to your proper time, shouldn't the traveling observer also see your time slow down relative to his proper time? Or does the observer see your time speed up relative to his proper time. Also, is dilation exactly the same in...
20. ### B Calculating Force of Ball-Spring Collision

Let's assume I have a ball moving at a constant velocity and it collides with a spring and the spring compresses n cm. If I know how much mass the ball has and the spring constant D, how would I calculate the Force? I mean since F = dp/dt I would have to know the time in which the stopping...

22. ### I How Dark could Dark Matter get?

We don't yet have a theory of quantum gravity, so determining it's subatomic structure is tricky.
23. ### I Double slit - properties of slit?

The distance that separates the slits is a factor, as is the distance from the slits to the wall at the back. Magnetic fields, charge etc. is not taken into account. If you are talking about the double slit experiment with light, then these two factors have no meaning, as light is not influenced...
24. ### B Energy-mass equivalence

You need a lot of energy to create a significant amount of mass. You need very little mass to create a very large amount of energy (as evidenced by the atomic bombs). When measuring the mass of a system, for extremely accurate measurements it is necessary to take the energy into account. Fun...
25. ### Best (or at least good) GR and SR textbook for a 15-year-old highschool student

Update: I got The Theoretical Minimum on Classical Mechanics by Leonard Susskind and I find it challenging enough to enjoy it. I am now aware that I have quite a long way to go :D

Thank you
27. ### QFT interpretation of Hawking Radiation

Hello, So I was reading about Hawking radiation and I read a QFT interpretation of it. It went something like this: A vacuum contains virtual particles (vacuum energy), which in qft can be described as waves that are out of phase and cancel each other out (matter and antimatter). I a black...
28. ### Calculus Good textbook for Mathematics

Yes, I have taken Maths as one of my main subjects. Thank you for your advice

Thank you!

31. ### Calculus Good textbook for Mathematics

Hey guys, so I was on this thread on tips for self studding physics as a high schooler with the aim to become a theoretical (quantum) physicist in the future. I myself am a 15 year old who wants to become a theoretical physicist in the future. A lot of people in the thread were saying that...
32. ### B Question regarding the equivalence principle

Ahh thank you. I was always confused what "local" meant.
33. ### Studying Where shall I start? (16 y/o wanting to become quantum physicist)

I'm 15 years old and have the same dream, so this thread is quite helpful for me too. Thank you :)
34. ### B Question regarding the equivalence principle

Hello, So I read that a person in a rocket accelerating at 9.8m/s^2 would feel the same pull downwards as a person standing on the Earth's surface. However, I can think of a few instances where you could tell the difference: - If you measure g (9.8N/kg) on Earth, you will notice that the...
35. ### Best (or at least good) GR and SR textbook for a 15-year-old highschool student

Ah yes, I've heard of Leonard Susskind. Thanks for the recommendation.
36. ### Best (or at least good) GR and SR textbook for a 15-year-old highschool student

Thank you for your advice. It may well be that I overestimate what I understand.

Thank you
38. ### Best (or at least good) GR and SR textbook for a 15-year-old highschool student

My apologies. What I meant by that is that I have a basic understanding of them.
39. ### Best (or at least good) GR and SR textbook for a 15-year-old highschool student

Hi, I'm a 15-year-old high school student and I was wondering what textbook you guys recommend for Special- and General Relativity. I'm familiar with the concept of the Metric Tensor and Christoffel Symbols, but I wanted a good textbook where I can really learn derive it all and gain a deeper...

Yeah
41. ### B Regarding z0 interactions

Oh ok. So a z0 Boson interaction is one where charge is conserved? (since the z0 carries no charge)
42. ### B Regarding z0 interactions

If there are no flavor changing z0 weak interactions, how do we even know that the particle exists? I thought that we could only tell which particle was exchanged by the particles it decays into. Is this wrong?

Thank you.
44. ### Quantum Is "Quantum Physics for Dummies" a good textbook for starting QP?

I've been reading about Quantum Mechanics for years now and I think it's time I bought a textbook and really learned the math. I'm 15 y.o. and have a working understanding of Derivitives, Integrals and Vectors. Is this textbook a good one to start with or is it too complex? Which one would you...
45. ### B Does the energy of an electron vary in the sublevels?

Ohh ok. Thanks for the explanation

Thanks!
47. ### B Does the energy of an electron vary in the sublevels?

I can’t find the page in the book, but here's a chart from google. As you can see each level has n number of sublevels.
48. ### B Does the energy of an electron vary in the sublevels?

Quantum by Manjit Kumar I read that there are energy levels n = 1, n = 2 (...) and that each energy level contained n amount of sublevels, so n = 2 is made up of two sublevels and n = 3 is made of 3 sublevels etc. Is this correct?
49. ### B Does the energy of an electron vary in the sublevels?

So I read that Bohr's atom has discrete energy levels that an Electron can orbit at and that each level has n amount of sublevels (if n = 2 then there are 2 sublevels). Does the sublevel that the Electron is in have to do with it's mass? Does an electron in energy level l and sublevel d have...
50. ### B Is The Planck Length the smallest length possible?

I am referring to the Lorentz transformation. What I am trying to say is that some things are mathematically possible but not physically.