So right now in calc 2 things arent looking so hot... I got a 60% on my first exam (20% of the total grade) and at this rate I am looking to get about a C in the class. I'm looking at pretty much all A's in everything else though (taking 16 credit hours). I am stuck in the mindset that if I get a C in that class, my chances of getting into a top grad school are pretty much nothing. Can someone convince me otherwise?
What's the reputation of your current department? One C will not kill you with straight A's otherwise. Absolutely not. But if your current department is top program, you could probably get straight Bs and still end up in a top program.
But in the end, letters of recommendation will probably count more than anything else anyway.
[QUOTE=JohnnyMo1;48843940]What's the reputation of your current department? One C will not kill you with straight A's otherwise. Absolutely not. But if your current department is top program, you could probably get straight Bs and still end up in a top program.
But in the end, letters of recommendation will probably count more than anything else anyway.[/QUOTE]
Going to Ohio State. So it's not an ivy league level, but among state schools it is a top school I believe.
[editline]6th October 2015[/editline]
That test was a fluke though. I know I can get a B, and if I get some stellar exam grades I can get an A. I just have to really work for it
Sounds like it's not really a problem at all then, especially if you're getting straight As elsewhere.
Also, start studying for your GRE early. For the most part it's just a filter to weed out the weak candidates, but a really stellar score can turn heads.
[QUOTE=JohnnyMo1;48728354]
But funny enough the final exam was so much easier than the homeworks I though it was a joke at first.[/QUOTE]
everythings relative i suppose....
i'll see myself out
[editline]7th October 2015[/editline]
[QUOTE=shadowdude14;48844553]Going to Ohio State. So it's not an ivy league level, but among state schools it is a top school I believe.
[editline]6th October 2015[/editline]
That test was a fluke though. I know I can get a B, and if I get some stellar exam grades I can get an A. I just have to really work for it[/QUOTE]
OSU is really good, though from the people i've known that go there, their reputation for being hard to get in is overblown, i had Ochem over the summer with a bunch of them, like all they talked about was getting drunk, and their classes are curved insanely, they were premed or biochem majors though
i've also heard their grad school is pretty great, half the professors at my college did their grad school there
[IMG]http://s14.postimg.org/qz987nwhd/BRUH.png[/IMG]
I know this is insanely simple, but I have a conceptual question about part B and C. If Box A is being pushed against Box B, the force exerted between them is different than if Box B is being pushed against Box A. Both cases would have the same acceleration, so I am having a little trouble understanding why the forces would be different. Can someone shed some light on this?
The acceleration of the two blocks must be the same. If the the forces were the same in both configurations, i.e. pushing on different masses, then the acceleration would not be the same by F=ma.
[QUOTE=Falubii;48855129]The acceleration of the two blocks must be the same. If the the forces were the same in both configurations, i.e. pushing on different masses, then the acceleration would not be the same by F=ma.[/QUOTE]
but arent they both moving? Isn't the total amount of mass that your moving the same in both?
The net force acting on the two block system is the same in both cases, and the total mass of the two block system is the same in both cases. But in each case a different block is being pushed by the external force. The block that is not being directly acted on by the outside force is oblivious to said outside force. All it sees is the normal force from the other block (as well as the frictional and normal force from the ground, ignore them for now). Let's say you push on the big block, and the big block pushes on the small block. The big block pushes on the small block only enough for the small block to accelerate at a rate matching the two block system. Now let's push on the small block, causing the small block to push on the big block. In both cases the acceleration of the system is the same (same external force, same total mass), therefore the small block must necessarily provide a larger force on the big block than the big block had to provide to the small block in the first case. This is because the big block has to accelerate as much as the small block had to accelerate in the first case, but the big block has more mass and requires a larger force acting on it.
I realize that my explanation was kind of long-winded. If you haven't already, I would recommend drawing a free-body diagram of both configurations, keeping in mind that both cases must have the same acceleration.
First year uni hit me hard. Maths has been okay but pretty difficult at times with matrices, cramers rule and improper integrals and all that shit, not too bad. Applied maths the same except for one test and programming has been piss easy even though it's my first time learning it, not difficult stuff at all really.
Physics has been a bitch though.
It's pretty much known that it's the most difficult course in my university, class dropped from 160 kids to 13 last year. I don't know how difficult it is compared to the international big leagues (probably not very) but the bastards decided that we should do the chain rule without having touched on it yet in pure maths (no advanced placement at school as well so I had no idea what it was), the physics class had to take an extra maths lesson to learn it. Panicked heavily in the first test of this semester too, was on gaussian surfaces and electric potential using line integrals and what have you, along with some capacitance and coulomb's law. Didn't get a good mark but i have a second test and practical's to bring my marks up.
Shit's tough, but hopefully I get through it because second year is apparently super easy comparatively.
That's a ridiculous drop rate.
Trying to arrive at the Kruskal-Szerkes coordinate system for the spacetime surrounding a Schwarzschild black hole in a way that I find logically satisfying for my thesis, and I've lost a fucking negative sign somewhere which I can't for the life of me find.
Pretty much every reference I find jumps wildly without any real motivation to solutions stating things like, "if we use this transformation we see that the resulting coordinate system is well behaved!" and it's fucking infuriating. Yes, you're right, that IS a well behaved coordinate system at r=2GM, but given the overall structure of it there's no way you're just supposed to guess that form from nothing.
Thankfully, I'm pretty sure I'm like 75-90% of the way to having the transformation complete with appropriate motivation at every step of the process, but either something small has gone amiss somewhere, or there's a mapping between what I've got written down here and what I'm looking for that I'm not quite seeing yet.
[QUOTE=Falubii;48866528]That's a ridiculous drop rate.[/QUOTE]
yeah most of the people who get into the course take physics as a alternate module for just the year to get their credits, so they don't care about it much at all
Schwartz's QFT book is great, but it's so annoying that he doesn't do index contractions the standard way. He doesn't bother to make sure one is upper and one is lower, because "having upper and lower indices on
the same object makes expressions difficult to read." Lol, no it doesn't.
Dammit Schwartz, do you not understand that vectors and covectors are different things!?
[QUOTE=JohnnyMo1;48895579]Schwartz's QFT book is great, but it's so annoying that he doesn't do index contractions the standard way. He doesn't bother to make sure one is upper and one is lower, because "having upper and lower indices on
the same object makes expressions difficult to read." Lol, no it doesn't.
Dammit Schwartz, do you not understand that vectors and covectors are different things!?[/QUOTE]
Surely he must only be doing that for objects that aren't actually tensorial in nature, right? Like just using summation convention for ordinary sums of scalars in order to do away with summation signs? Otherwise, unless he's using some alternate notation, I can't see any conceivable way that he'd properly be able to keep track of what's being contracted properly.
Then again, unless he's going into QFT in curved spacetimes he'll just be using the Minkowski metric, right? So worst case scenario if he is doing this with tensorial objects he'll just have to make sure he's not losing negative signs I suppose.
[QUOTE=sltungle;48896747]Surely he must only be doing that for objects that aren't actually tensorial in nature, right? Like just using summation convention for ordinary sums of scalars in order to do away with summation signs? Otherwise, unless he's using some alternate notation, I can't see any conceivable way that he'd properly be able to keep track of what's being contracted properly.
Then again, unless he's going into QFT in curved spacetimes he'll just be using the Minkowski metric, right? So worst case scenario if he is doing this with tensorial objects he'll just have to make sure he's not losing negative signs I suppose.[/QUOTE]
He won't lose negatives because it doesn't actually matter which index is up and which is down when they're being summed over (write it out explicitly using the metric to raise and lower the indices to see it easily) but it still looks wrong to anyone who has been using the, you know, established convention. Maybe he should be less concern with what confuses him and more concerned with what might confuse his readers. I hate losing the simple visual interpretation of "this vector and this covector acting on each other" and getting instead this scalar made of two nebulous things.
[QUOTE=JohnnyMo1;48896828]He won't lose negatives because it doesn't actually matter which index is up and which is down when they're being summed over (write it out explicitly using the metric to raise and lower the indices to see it easily) but it still looks wrong to anyone who has been using the, you know, established convention. Maybe he should be less concern with what confuses him and more concerned with what might confuse his readers. I hate losing the simple visual interpretation of "this vector and this covector acting on each other" and getting instead this scalar made of two nebulous things.[/QUOTE]
I meant more if he was being careless and just forgetting that the whole 'summation' thing includes negative terms in general (i.e. that you're not just adding terms positive definite as you would when ordinarily squaring a 3-vector for example). It puts me in the right mindset when I see index notation up and down and I'm naturally less likely to slip up. When I see it all down I'm reminded of when I first came across index notation (solid state physics course weirdly enough; and god it wasn't explained very well then) and naturally default to wanting to think of things as 3-vectors.
But yes, the established convention is definitely incredibly helpful. It's these sorts of things (clarity in texts on what are otherwise seen as incredibly difficult, complex subjects) that make famous books famous for a reason I suppose.
It does seem really good overall though. Huge amount of content (as one would hope from almost 900 pages)
Carroll, page 60 he states for an n-dimensional [;C^{\infty};] manifold that
[IMG]http://i.imgur.com/McDrA9j.png[/IMG]
What does he mean by equivalent, is that the same as diffeomorphic (i.e. the same up to some [; C^{\infty};] map?) Also, why would that matter if two spaces have a different atlas. Isn't their equivalency purely based on their [; C^{\infty};]-map? I don't see how that requirement is useful, unless if having a different atlas would imply there is no such diffeomorphism and thus the spaces aren't equivalent.
I'm also going to ignore is comment/example about Lie groups being manifolds because that seems to bring me in an endless Wikipedia cascade of definitions :v:
Proposition 1.17 in [I]Introduction to Smooth Manifolds[/I] by John Lee:
Let M be a topological manifold.
(a) Every smooth atlas A for M is contained in a unique maximal smooth atlas, called the [B]smooth structure determined by A[/B].
(b) Two smooth atlases for M determine the same smooth structure if and only if their union is a smooth atlas.
This morning, I read in the paper about the Delft University of Technology study led by Dr. Ronald Hanson, which seems to demonstrate proof of entangled electrons interacting instantly over a distance. It was published yesterday in Nature.
I wanted to ask you guys about its significance. There aren't any news threads here on it, but from my limited understanding, it sounds pretty darn important.
[QUOTE=DChapsfield;48959293]This morning, I read in the paper about the Delft University of Technology study led by Dr. Ronald Hanson, which seems to demonstrate proof of entangled electrons interacting instantly over a distance. It was published yesterday in Nature.
I wanted to ask you guys about its significance. There aren't any news threads here on it, but from my limited understanding, it sounds pretty darn important.[/QUOTE]
It's nothing groundbreaking or unexpected, just the closing of some previous loopholes. Yes, entangled particles are neat, but they don't allow any sort of communication of information faster-than-light. The "instantaneous" effects are really just correlations.
I've been wondering, if you were accelerating toward the speed of light, could the effect of time dilation make it look from your perspective as if were just linearly accelerating faster and faster]?
Any idea how to do this problem? I have no idea where to start
[IMG]https://i.gyazo.com/670a498ebe186e8fd2725c7d125d0cdb.png[/IMG]
[IMG]http://i63.tinypic.com/14e84ea.png[/IMG]
There's a derivation for you with some light handwaving.
Happy 100th birthday of the Einstein field equations!
[IMG]http://i67.tinypic.com/1z2eiaw.png[/IMG]
Still ultra sexy even in their old age.
[QUOTE=JohnnyMo1;49184578]Happy 100th birthday of the Einstein field equations!
[IMG]http://i67.tinypic.com/1z2eiaw.png[/IMG]
Still ultra sexy even in their old age.[/QUOTE]
Mmmmmm, that curvature.
[QUOTE=Bradyns;49184683]Mmmmmm, that curvature.[/QUOTE]
Look at those subtle natural units... the tasteful covariance of it.
[QUOTE=JohnnyMo1;49184578]Happy 100th birthday of the Einstein field equations!
[IMG]http://i67.tinypic.com/1z2eiaw.png[/IMG]
Still ultra sexy even in their old age.[/QUOTE]
God it's a beautiful equation... or... set of equations I guess.
I wanna do some proper reading of Kaluza-Klein at some point after I go back through my GR book and make sure I understand it to the best of my ability.
The shit the CERN FB page has to put up with...
[IMG]http://i.imgur.com/WJXS1Pi.png[/IMG]
(there were about 3 more paragraphs)
also one of my favorites:
[IMG]http://i.imgur.com/5REYLIj.png[/IMG]
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