/sci/ - Science & Math

[Anonymous No.1919541]

hi /sci/,

what is mathematical physics? how would you define it to someone who wishes to study physics but cannot decide on concentration?

[Anonymous No.1919547]

Bump. I have similar interests.

[Anonymous No.1919545]

[Josef !!nUf2NflSAyw No.1919555]

Experimental physics: Verify things predicted by theorists, measure things and let theorists improve their theories.
Experimental theory: do what experimentalists do, only that your experiment runs on a supercomputer.
More theoretical theory: Together with the experimental theorists, make the predictions needed to explain the measurements of experimentalists, or invent new theories required by their data.
Mathematical physics: You're to a theorist what a theorist is to an experimentalist. "Let's add a semi-circle to all points in space and see how that changes physics".

[Anonymous No.1919569]

Mathematical physics is when you do theoretical physics but still care about the mathematical rigour.

[Anonymous No.1919573]

It's when you realize you're gay, OP.

[Anonymous No.1919586]

>>1919555
>>1919569

thanks for the explanations, but, can we say then, any mathematically rigorous physics study is mathematical physics? or does it have more definite borders? if I work in quantum field theory, or hamiltonian mechanics, I know it's going to be mathematical physics, but how can I make a more solid picture of what it is?

[Anonymous No.1919588]

>>1919586
When you realise you're gay, OP.

[Josef !!nUf2NflSAyw No.1919599]

>>1919586
The more you use instead of abuse math to do physics, the more mathematical physics it is.
Theoretical quantum theory: <span class="math">\psi[/spoiler] is a thing that is a probability density when absolute-squared
Mathematical quantum theory: Psi is a section of the complex line bundle over Minkowski space

[Anonymous No.1919604]

>>1919588

[Anonymous No.1919622]

>>1919599

so more formalism results in more mathematical physics. ok, if so, when i do high energy physics, where math is mostly abused and try to use more formalism, can we say that i am the intersection of both?

I know I am just wandering around the terms and not the concepts themselves, but I want to make it clear first.

[Josef !!nUf2NflSAyw No.1919638]

>>1919622
Lagrangian: <span class="math">-\frac1{8\pi}(\partial_\mu A_\nu-\partial_\nu A_\mu)(\partial^\mu A^\nu-\partial^\nu A^\mu)+A_\mu J^\mu[/spoiler]
Mathematical Lagrangian: <span class="math">-\frac1{8\pi}\mathrm dA\wedge*\mathrm dA+A\wedge\mathcal S[/spoiler]
One of them is ugly, but requires significantly less math to be understood. Can you guess which one? ;)

[Anonymous No.1919639]

[Anonymous No.1919644]

>>1919638

so for a guy who is studying physics and having an education of formal math, 'mathematical' physics of any area is more relevant. thanks for the clarification. I love that mathematical elegance.

[Josef !!nUf2NflSAyw No.1919660]

>>1919644
One postdoc at my university really does the "let's add dimensions" stuff. It's called "particle physics transcending the standard model". The one example he gave me was really adding a U(1) ("circle") to each point in space, and then identifying both sides of the circle with each other, resulting in a semi-circle everywhere. Start doing physics in that space, see what comes out.
No, this was not done with an eye on how and whether this is possibly suitable for any experiment, but this is where all-new ideas come from.

[Anonymous No.1919688]

>>1919660

hah, that sounds fun though. I guess I got your point, and it seems I have to start forming ideas first to decide on a concentration.

[Josef !!nUf2NflSAyw No.1919699]

>>1919688
Go ask your professors, postdocs, phd students what possible topics are. Don't be afraid to crash into a lab and ask "guys, what are you doing here". Nobody will throw you out per default, but make sure you're not meeting somebody who just went through 2 weeks beamtime at a synchrotron, their nerves miiiight be a bit .... uh, exhausted.
Just remember, every phd student has been like you a few years ago. When you're far enough to ask yourself whether you want to do theory or maths or experiments, you're one of the serious students anyway. You will get an explanation. (Bring time. I haven't had a talk less than 30 minutes yet, and that includes asking a guy where some other guy has his bureau.)

[Josef !!nUf2NflSAyw No.1919718]

>>1919699
sports time
back in a few hours
(also, my email isn't fake, feel free to ask almost anything)

[Anonymous No.1919719]

>>1919699

thanks for the ego pump and advice. I try to speak to some guys at least, to get a sense, but why not ask everyone for sure. the thing about my university is that we have more experiment guys here, and they are mainly concentrated on photonics and solid state, so I have less guys that I can ask about these.

[TheHeart: Roxas !Ncc/yhRygA No.1919744]

>>1919547
>>1919573
>>1919555
>>1919569
>>1919586
>>1919588
>>1919599
>>1919622
>>1919638
>>1919644
>>1919660
>>1919688
>>1919699
>>1919718
>>1919719
>>1919541

Nope! You're wrong!

[Anonymous No.1919787]

>>1919744

then could you be more specific?

[TheHeart: Roxas !Ncc/yhRygA No.1919797]

>>1919787
No.

[Anonymous No.1919802]

>>1919797

[TheHeart: Roxas !Ncc/yhRygA No.1919809]

I like playing with you guys, it's fun :D

[Anonymous No.1919827]

[Anonymous No.1919861]

How the hell do u calculate motions in a fourth dimension, i know this probably is an realy stupid Q but in like an second dimension u got y, x and third dim y, x and z. and fourth dim its y, x, z, and t? how do you calculate the T?

And now for the real facepalm. those the fourt dimension andthing to do with Quantum physics?

[Anonymous No.1919872]

>>1919861

[Anonymous No.1919901]

>>1919861

minkowski spaces. problem solved.

[Anonymous No.1919912]

[Anonymous No.1919924]

physics are dependent on mathematics, I don't see how you can do physics without it. Maybe it's a little different.

[Anonymous No.1919942]

>>1919924
There's a fucking huge difference between setting up models, doing calculations and rigorously proving shit, generalizing into N dimensions and whatnot. For the latter, you need a way more fluent understanding of the underlying math.

[Anonymous No.1920371]

[Anonymous No.1920439]

[Anonymous No.1920443]

>>1919901
spoken like someone that clicked on a wikipedia link and has no idea what they're talking about.

[Anonymous No.1920463]

>>1920443

inb4 he was trolled.

[Anonymous No.1920465]

>>1919942
it's called verification and validation. use computational people need to have solid understanding of the physics and the mathematics (and the computational know-how) to actually solve problems. many fields only require one of these.

signed,
computational physics guy

[Josef !!nUf2NflSAyw No.1920633]

>>1919861
You calculate "the T" like you calculate the x. (Actually, I've never calculated an x, but that's another story.)
There are some things that look weird on first encounter, for example in special relativity, the norm square of a vector isn't simply <span class="math">x^2+y^2+z^2+t^2[/spoiler], but has a minus before the t, <span class="math">x^2+y^2+z^2-t^2[/spoiler], so the vector can have negative length square. (Nope, no complex numbers involved, there are plenty other things that become negative when squared, not just i.)
Get used to those minor changes and you can calculate in as many dimensions as you want.

>>1919924
OOOOh yes you can. Lectures on experimental physics usually pick some formulas without deriving them, ask you to use them to solve certain problems, and that's it.
It's as if you were given an English-German dictionary and should interpret Faust with it.