/sci/ - Science & Math

300k starting?

>>1246340
No, my stipend is about 28k for the school year, and another 8k for the summer.

Does the arrangement of protons within the nucleus influence the motion of the orbiting electrons to a measurable extent, or do we treat the nucleus as a single point?

>>1246354
For the most part, you ignore the structure of the nucleus when you are calculating electronic structure.

However, if you are really into calculating atomic spectra, the hyperfine splitting starts to take into account the spin of the nucleus, not the shape, but the spin

What is the population of the grizzly bear in Albert, Canada?

Why is there no magenta in the spectrum?

>>1246327

What field are you heading into?

>>1246363
Cool. Thanks for that, I'd been wondering.

>>1246364
I have no idea. If I had to guess, I'd say a bear takes up about as much space in a forest as you can walk in a day. Walking at 2 mph for 6 hours or so. I don't know.

Area of Alberta is probably something like 250k mi^2, so I'd guess something like

2000 bears?

Help me, Ive got Physics I exam coming up 24.06 :(
Any pointers for what is the most important stuff I should learn?

>>1246372
this has always mindfucked me, we perceive a looped spectrum so it's really just our brains fucking with us. In reality magenta must be multiple light frequencies (650 and 405nm work well together)

Not a question about theory, but:

To what degree have we been able to get anti-particles to slow down so far?

When we produce them, they travel at a good deal of c do they not?

Also, have we experimentally proven that anti-particles have positive mass?

I realize that most physicists think that they do, and they probably do, but because of the high speeds they travel at we haven't been able to confirm it, last I heard.

>>1246372
Magenta is a mixture of red and blue lights. Its not a pure frequency of light.

>>1246378
Condensed Matter

>>1246388
Depends on what course you are in.

What are you going to do for money?

I.E. careers you desire

>>1246395
There has been mixed success in isolating and maintaining anti particles.

In fact, recently at CERN they created anti-hydrogen.

You contain the antiparticles with a magnetic bottle I believe.

Anti-particles have positive mass in the sense of inertial mass.

It remains an experimentally open question whether they have positive gravitational mass, I believe, but there are very good theoretical reasons to rule out them having negative gravitational mass.

>>1246417
I plan on trying to stay in Academia. After the PhD, get a postdoc or two, after that try and get a professorship. Teach and do research at a university.

What implications does the 'holographic universe' theory have?

Well, Im thinking of taking Physics as my second faculty. For now, just studying Mechatronics.
My Physics I contains of Electromagnetism, Mechanics and Einstein's Relativity theorem. Some modern Physics too. How's that sound?

>>1246431
do you think there are more opportunities in engineering or physics as far as careers?

>>1246424

Thank you for that.

If you can contain them, can't you then tell whether or not they have positive/negative gravitational mass?

I imagine it would be pretty expensive to do though.

if an electron is exited by say UV light,, what rules makes it emit it as visible light ( ive heard this mentioned but never seen where it comes from ) the UV / visible is ofcourse just an example - i mean in general

>>1246439
Ah, I haven't really looked into it beyond the cursory news articles that have been showing up, but the idea is that all of the information of our universe could be encoded on a two dimensional surface,

similar to how in Complex Analysis, an analytic function is completely determined by its values on a closed surface.

The implications would mean little for your everyday life, but seem to have some pretty intense theoretical implications. I know that some talk has been about trying to experimentally verify the holographic principle by looking at the nature of the noise at gravitational detectors.

>>1246446
Bah, I don't know. I think you could pretty much get any given job with either degree. People underestimate how many job opportunities there are for physics majors.

>>1246454
Gravity is weak, very weak. Hard to detect.

>>1246458
Looking at the atomic spectrum of something like hydrogen, in theory you can transition between any of the different states (of course there are certain selection rules dealing with spin and parity),

After being excited, the electron can de-excite again by falling into any of the lower energy levels allowed by the selection rules. So you don't have to emit light at exactly the same frequency you absorb it at.

Things like glow in the dark materials however I think are a little more complicated then that.

How long did it take to get a PhD?

>>1246500
I'm still working on it. In the US, the time for a physics PhD is variable, but usually something like 5 or 6 years. Of course in the US, you typically go straight from bachelors to PhD, so its not too bad.

>>1246506
What school, what what kind of job will you have after?

>>1246495
There are 2 types of work a physicyst is "qualified" to do, in many people's opinion- professorship/research and work at a national lab. But if a phd in physics applied for a position which required a masters in EE... I'd be hard pressed to know who would get the job.

And there's not many jobs at national labs, and so much bureaucracy

Heres a question for ya, why can't scientists run the country?

Do you think it is a good idea to get a second faculty? I honestly like the idea of getting an engineers degree and physics too. But is it accomplishable ? Also:
Can you explain what exactly is the "displacement current" or something like that ?

>>1246517
Lets just say Ivy. Afterwards I will apply to about 50 different postdocs probably. That seems to be a typical number.

>>1246521
I mean, masters are a different question, but I really don't think there is much distinction between an engineering and physics bachelors, except that a physics bachelors would probably be seen as more general.

Additional, why can't scientists run the country. No idea, there are notoriously few scientists in congress, and I think its a shame.

>>1246533
http://en.wikipedia.org/wiki/Displacement_current

Whenever matter falls into a black hole does it turn into bosons? Does the baryon/lepton number in = the numbers out? Would it violate a law of conservation if it didn't?

>>1246533
I assume faculty is your term for majors? I think it really depends on the school.

Ah, the displacement current. Neat. Its the additional term in Ampere's law that Maxwell contributed.

Curl of B = 4 pi J + 1/c dE/dt,

that dE/dt term is the displacement current. Why is it called displacement current? Thats an interesting question.

It goes back to the fact that Maxwell had developed a mechanical model for the electromagnetic field involving a bunch of ball bearings, big ones and little ones arranged in a lattice. The spin of the big ones was the magnetic field, and the little ones, if they moved represented a current in a wire or something similar.

I don't know if my description has been good enough, but if you picture this lattice of little ball bearings and drag some of them to the right, the large ones will rotate surrounding this 'wire'. Thats the magnetic field.

How did Maxwell figure out that there was a term missing from ampere's law? He did a thought experiment with his mechanical model. Imagine changing the current in a wire instantaneously. This would cause all of the little bearings in the lattice to displace slightly from their origin. They would jerk a bit. That jerking looked like a little localized current. Hence the displacement current.

What careers are your classmates in? Are there any careers outside academia which they would not be better served by an engineering degree?

>>1246558
Interesting question. I'm not terribly sure. I'll tell you what I do know. A black hole is described with only three parameters, its radius, its charge, and its spin.

So, as far as I've been told, black holes should have no notion of lepton or baryon number.

Then again, lepton and baryon conservation come from quantum field theory, which doesn't exactly play well with general relativity anyway.

As far as I know its an open question.

>>1246578
A few. A buddy of mine is a beam technician at a national lab now. Another one works for a sort of engineering think tank. A few others work for a hedge fund on wall street (thats probably one that would not be better served by an engineering degree). Another ones a teacher. A bunch are fellow grad students.

Is dark matter something that all physicists take as real, or do they seem pretty open minded to something like Modified Newtonian Dynamics?

Also, is the Graviton an accepted theoretical particle? If not, how is gravity viewed; as an emergent property of spacetime?

Do you have a girlfriend? lol

>>1246619
Dark matter is pretty real now. See the Bullet Cluster. That was a pretty big nail in the modified newtonian dynamics coffin.

The graviton is an accepted particle in so much as we know that a graviton if it exists would have to be spin two and massless (or very nearly so). So its talked about a lot as though it exists, but it hasn't been observed and probably wont be for a long time.

Gravity is most often viewed through general relativity, a remarkably successful and correct theory for describing things on galactic scales.

You don't really need to think about gravity when you are doing anything remotely quantum mechanical since it is so weak, unless of course you are actively trying to come up with a quantum mechanical description of gravity.

>>1246643
Yes.

Well, that didnt really determined your gender, but I assumed you are male. Are there any female PhDs that are considered "hot" by most of males around?

>>1246699
In our class there are 20 or so students, 3 females, two of them hot.

>>1246619

I asked an astrophysics lecturer once about MOND, he said that there is so much internal conflict within the dark matter camps that it would be unacceptable to not at least consider alternatives. That having been said, evidence for dark matter is now pretty good - but the specifics haven't been ironed out.

How was the workload for your undergrad studies in Physics?

I am thinking of pursing Physics this fall and I am curious about the workload.

Are you spending most of your life doing science? I love it. Love technology and stuff, but also feel a bit scared if it comes to sacrifice every single minute of my time for it. How much time does it take from your everyday life? I mean studying now, getting the PhD, stuff.

>>1246725
I went to a university notorious for the workload, so I spent a lot of time working.

I think that will vary a lot from university to university, but the thing to keep in mind is that the only way to get good at physics is to work at it.

One time I made an off hand comment about Feynman being smart, somehow implying that he was unnaturally smart. My advisor, a really old guy who knew him mentioned that when you would go into Feynman's office, the first thing you noticed was the bookshelves. One of them on each wall, shelves and shelves of notebooks stacked two deep. Each filled with problems he had worked.

>>1246735
Once you get past your classes, being a graduate student is pretty laid back. Several grad students are starting families. You really only have a few hours in the week that you are obligated to be somewhere (this is for theory of course, experiment you are sort of expected to put in a full day).

But, I think its more or less a 5 to 9 kind of setup, with some late nights one the days before you need to present something.

>>1246720
Haven't they found dark matter galaxies? That is kind of bad for MOND isn't it?

Could you help me understand Ampere's law?

>>1246619

you might want to watch this video. its 1 hour long, but it explains what we currently know about the universe, and why. really interesting IMO

http://www.youtube.com/watch?v=7ImvlS8PLIo

what exactly is the n body simulation? i hear people mention it and then i see pretty galaxies

>>1246735

i would totally sacrifice my life for science, if only i was intellectually capable of it. my greatest dream is to collaborate with the progress of our species by adding new knowledge that would be taught by generations and generations of scientists. unfortunately, i'm too stupid for this, and instead i'm coding for a living.

>>1246761
Hmm. A few different equivalent ways to state it.

Curl B = mu J
Line integral of B = mu * current enclosed

Its a physical law, discovered from experiment. Its utility is given a source of magnetic fields.

On the face of it, it's a parlor trick. The line integral of the magnetic field is equal to the current enclosed, reglardless of the closed curve you draw.

Its utility however is in finding magnetic fields for situations of high symmetry, in much the same way you use Gauss's law to calculate some electric fields.

Think of it as the magnetic equivalent of gauss' law.

That help?

>>1246772
an N-body simulation is just what its name implies. Create N different objects, each with in theory different masses, and let them interact through gravitational forces.

Those pretty movies are because computer scientists have found very sophisticated algorithms for solving this problem, usually though to be very hard.

So its usually used as a test to see how kick ass your graphics card is.

>>1246791
Does help a bit. Problem is since I never understood it for whatever reason, I end up trying to biot-savart things that could have been really simple if I thought about it for a sec.

>>1246326

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>>1246811
The cases I know work are a wire, a solenoid, a toroid, and a plane of current. You could try your hand at solving for the magnetic fields everywhere in space using Ampere's law on those cases.

>>1246790
>>1246790
Dude, there is no such thing as 'too stupid'. Really. There is no other way to contribute to science but hard work. Having said this and being motivated I shall take the second faculty - physics. Thanks to this thread.

Where did you go to college?

>>1246805
Thanks OP

>>1246829
Isn't the magnetic field of a toroid contained completely within the toroid?

>>1246836
Lets just say California.

>>1246790
>>1246833
I concur. You can always do science if you want to. Its really not as difficult as people make it out to be. Just takes some passion and some willingness to spend time at it.

>>1246851
Why can't you tell me the name of your college?

>>1246846
But what is the r dependence of the field internally? Also you should be able to demonstrate that using Ampere's law. That is the kind of argument Ampere's law is good at.

>>1246860
This is an anonymous board after all.

>>1246865
Thanks man :)

I have a final coming up real soon so I'm trying to fix up my weaker points.

Is the inside of an event horizon of a black hole haunted by ghosts, and if not, how can you prove your claim?

Whats the effect of the interference of those two electromagnetic waves?
E1=E0cos(wt-kr1)
E2=E0sin(wt-kr2)
for what r2-r1the amplitude of new wave is the smallest?

>>1246888
No its not. No I can't prove it.
>>1246897
I don't want to do your homework for you.

So just tell me if solving the equation makes it right:
E1=E2? Then expressing r2-r1 by anything else.

>>1246909
You can superimpose the two waves to see how they would interfere, i.e. add them together. Then try and answer the question.

Grade 10 student here
I always wondered how do we know how many electrons are spining around a certain nucleus ? From what I understand atoms are smaller then the lenght of a lightwave so a microscope will do nothing thanks

>>1246975
In in my second year.

>>1246975
We can remove electrons from atoms by heating them up. It Ionizes them. By ionizing an atom completely, you can then measure its charge to determine the charge of the nucleus.

We know that when its not excited an atom has just as many electrons as it has protons. The charges have to balance, otherwise the atom will preferentially pick up more electrons.

What is in betwen the electons and the nucleus ?

If they are attracted to each other so much, why don't the electrons in a atom just hit the protons rather than orbiting around them.
RIDDLE ME THIS

>>1247022
Empty space.
>>1247024
Ah, that puzzled many physicists for many years. And then quantum mechanics was discovered. I think the easiest way to explain it is the uncertainty principle. If the electrons fell into the nucleus, we would know where it was, the nucleus, and its momentum, zero. That can't happen.

I am very educated in math, but total newfag in physics, how do i best learn physics?

>>1247031
please tell me you're fucking trolling

>>1247053
Textbooks. If you know a lot of math, the Landau Lifschitz series will get you up to speed with pretty sophisticated physics. You'll have to be comfortable with multivariable calculus, differential equations and linear algebra.
>>1247060
No?

I am an aspiring materials scientist (gettin my BSc next year). Since youre into condensed matter, can you give me any insight or advice into how interatomic potentials work (aside from the textbook LJ stuff) and what use they have for real world applications?

>>1247031
We don't understand the way it works, so it must specifically be making itself impossible to understand?

That sounds more like the kind of logic that should be coming from churches.

>>1247100
When modelling large systems, it is too hard to do a 'true' physical calculation. You can do DFT (density functional theory) but only for a hundred or so atoms. In order to model objects with thousands of atoms, you need to do something simpler.

Interatomic potentials are a way to try and approximate the physics of a large material. You say that the atoms all interact classically as though they each created a potential of a certain form.

These are in very active use. Thousands of different interatomic potentials have been dreamed up, each tailored to answer specific kinds of questions (electronic configuration / elastic properties, etc)

>>1246327
How much do you know about high-Tc superconductivity?

>>1247104
No, we understand how it works. I was giving a simplistic argument motivated only by the uncertainty principle since I figured most readers were not acquainted with the details of quantum mechanics.

Trust me, Quantum Mechanics is not magic. It is a complete physical theory that works. Its true that it seems crazy and counter intuitive, but we have every reason to believe its correct. It makes predictions that are born out by experiments.

>>1247127
Not enough. Been to several conferences where lots of professors each take a stab at explaining how it occurs, but there is no real successes yet, but there is progress.

What do you think of string theory?

>>1247100
Additionally, if you want to hit the ground running. ASE (Atomic Simulation Environment) is a really nice python package for doing, you guessed it, atomistic simulations.

It incorporates several calculators, some of which have access to a bunch of interatomic potentials.

The 'bible' package when it comes to interatomic potentials is LAMMPS, but thats C and harder to learn.

Interestingly enough, I'm actually working on interatomic potentials right now.

>>1247153
I think its a terribly attractive theory. If it works, you could explain all of physics with a single dimensional quantity.

Unfortunately a lot of work still has to be done.

If it works of course, its not going to replace all of the rest of physics you use. If current progress is any indicator, if someone manages to demonstrate you can get all of existing physics from it, calculations in string theory would still be too much work to be worth it except if you were doing extremely high energy or extremely speculative cosmology type stuff.

Which field of Physics do you believe has the most potential for growth in relationship to future PhD students?

I personally have been looking at Particle Physics as a future possible interest.

>>1246592
Ah yes, econophysics.

>>1247170
What I don't understand is how someone could ever prove string theory. I mean, studying things at the particle and subparticle level is already incredibily hard, how could someone ever dream of connecting certain properties of matter and energy to subsubsubparticles, the so called strings?

>>1247202
Honestly, I think particle physics is a little saturated. Then again, with the LHC turning on, there is going to be a lot of new data coming in.

Condensed matter is a growing field as there have been a number of recent advances, as well as the holy grail of High Tc superconductivity on the horizon.

Gravitational physics is getting interesting with LIGO collecting data.

Plasma physics is growing with the start of the ITER project and promise of commercial fusion in the next generation of physicists.

Accelerator Physics is all waiting for the ILC to get going, but once it does will need new blood, most of the high energy experimentalists are getting old.

All in all its a really exciting time to be in physics.

>>1247219
It takes a lot of complicated math. But it can be done. In principle.

>>1246592
>>1246592

does your friend happen to be a beam technician at NSLS at brookhaven?

>>1247159
thanks, man.

what are you using them for?

>>1247232
Sorry, no. SLAC.

>>1247234
Actually, trying to make them better. We are interested in systematically testing the existing potentials to see how applicable they are to questions outside the ones that were used to generate them.

I'm trying to make your job easier and better. A noble goal, but you gotta shoot high.

>>1247226

interesting...one thing I know is...I would like to be involved in some sort of experimentation. I'm a hands on person :P

>>1246395
Not OP but physics grad student.

I'm friends with the research group at Berkeley that is building the magnetic trap for antihydrogen at CERN and have gone to several of their meetings.

We (humanity) haven't created sufficiently cold anti-hydrogen to be able to measure whether mass is positive or negative, though the general consensus is that negative mass doesn't exist.

A bigger question concerns the spectrum of anti-hydrogen, to test for asymmetry with the hydrogen spectrum and better understand CP violation.

In case you care about the technical problems they have in trapping it: the positrons cannot be sufficiently cooled before entering the trap, and have energies on the order of 1 keV. They must be on the order of a few tens of eV to be sufficiently contained. Exacerbating this problem is that the opening of the trap is leaking blackbody radiation inside, heating the particles still. They were working on a type of metallic grating that would block much of the radiation (like the window on a microwave) last group meeting I went to.

>>1247299
Ooops. Errata:
I meant Kelvin instead of eVs.

e+ are ~kK, need ~50 K, as far as I remember.

>>1247287
There will always be spots for experimentalists in all fields. I don't think you have to worry.

But Accelerators is a nice field to get into. Like I said, most of the current guys are on their way out and especially if there is success at the LHC, accelerators will always be in demand.

SLAC just got the first 4th generation light source going. Good times

>>1247299
Sweet. Very interesting work. Was I right about the use of magnetic bottles? I'm not really up to speed with the technical details.

This may sound very silly, and in the current landscape of physics it is, but I'm going to propose it anyway.
Suppose we forget everything we know at the moment (or think we know, there's no absolute proof) about general relativity, space-time,... Wouldn't it be possible to approach mass as we approach charge? Charges attract and repel. What if masses do the same? We already know that masses attract eachother, in terms of gravity. What if there are also two kinds of mass, positive and negative? And that everything around us is made out of one kind of mass. This would imply that mass of the same type attract each other. This could be a reason of why the universe is expanding. Because there is another kind of mass, which repels the normal mass, with the same gravitational force?
I know it sounds stupid, but still.

>>1247340

Yep, they are using a Penning trap, i.e. a cylindrical geometry, with a solenoidal B field confining the particles radially, and an electrostatic well along the z-axis.

It's called the Alpha Collaboration (as in, the Lyman-alpha spectral line of Hydrogen)
http://alpha.web.cern.ch/alpha/

>>1247388
Its an interesting thought. The first problem that comes to mind is the equivalence principle. I.e. that gravitational mass is the same as inertial mass.

You can't really have negative inertial mass. So implying that some things had negative gravitational mass would negate the equivalence principle.

The only problem with that is if it negate the equivalence principle then general relativity has to be incorrect. Gravity would become no more complicated than electricity and magnetism. No curved space and all that.

Now, I know you said forget about general relativity, but the trouble is that we have an inordinate amount of data after years of collecting astronomical measurements, which very /very/ tightly constrains the forms of an acceptable theory of gravity. General relativity fits the bill however, and fits it remarkably well.

Not allowing curved spacetime and making gravity no more complicated than electricity and magnetism however, would not. You could not be able to describe light bending around a gravitational source for instance, or at least you'd be off by a factor of 2.

>>1247407
Sweet. Thanks again for the link. I'll read more about it.

what about oblique launch, what do you know about this

>>1247425
Not sure what you mean? Are you talking about trying to find trajectories for a rocket or satellite or something similar?

>>1247416

And what if you would use the 'new' definition of gravity and try to find a correlation with electromagnetic waves? So that mass has an electromagneticgravitational impact on other mass, on waves and vice versa. Wouldn't that (theoretically) be able to solve (some) of these difficulties with negating the curved space-timemodel?

Ofcourse finding such relation would't be that easy, and it's obviously more convenient to continue on the path we've taken now. Perhaps those paths will convert to the same truth.

>>1247439
oblique projectile?

>>1247455
What about it?
>>1247454
You might be interested to read about Kaluza-Klein theory. Its a unification of gravity and electromagnetism in a 5 dimensional space. Since its creation, its lost favor due to the success of general relativity, but it served as a sort of inspiration for string theory.

are quantum computers possible in the next 100 years?

>>1247466

Thanks for the tip :)
I have to go now, but it was enriching ^^

>>1247473

I'd like to know this.

>>1247473
Quantum computers consisting of a few qubits have already been built and performed simple calculations.

The trouble now is scaling up to thousands of qubits. The largest difficulty seems to be the lifetime of the quantum states. People are working on it, and its probably only a matter of time before it gets done.

In my humble opinion, topological quantum computers seem to be some of the most promising (you get an intrinsically long lived quantum state, and seem to be scalable, unfortunately there are no working examples yet)

>>1247481
As a follow-up, a couple months ago we had colloquia a couple weeks apart, both on quantum computers and their progress.

The first guy made a bet with one of the professors in our department on the time for the first commercial quantum computer at 15 years.

The second guy was much more pessimistic and said 50 if we are lucky.

>>1247483
has it shown promise of efficiently computing beyond-P complexity classes?

or is this beyond the scope of physics?

>>1247497
Schor's algorithm seems to be the best quantum computing success.

Its a P time prime factorization algorithm.

I'm not entirely hip to the language of complexity theory, but it has been demonstrated that quantum computers are more powerful than classical ones as I understand it.

>>1247497
That is why the primary funding source for quantum computers is the NSA. There exists the algorithm to factors primes in polynomial time, all we need now is a computer with a sizeable number of qubits.

If you get a quantum ipod in your lifetime, you can thank the NSA

>>1247507
Quantum computers aren't more powerful, they are just differently powerful. There are some things they're good at and some things they're terrible at. A lot of people make the mistake of associating quantum computing with nondeterministic computing, but they're nothing alike. A quantum computer can't solve a problem in NP in polynomial time.

>>1247526
I suppose you are right. No one makes claims that quantum computers can do NP problems in P time,

but there does exist a growing number of P-type algorithms like Schor's for which no classical counterpart exists.

Alright guys, OP is going to take a break. Will check back in an hour or so.

>>1247483
>>1247483
>>1247483


bitch please


the problem is making them.


more's law is already limited by semiconductor manufacturer's unwillingness to invest in substantial infrastructure that would alleviate our absolute reliance on silicon.


is it possible to go out and buy a super duper fast CPU, one that is many times faster than the fastest commercially available chip from Intel or IBM?

yes

will it costs 10s of thousands, if not hundreds of thousands, of dollars?

yes
if Intel, IBM, AMD, etc invested hundreds of billions into developing infrastructure for the cheap fabrication of non Si based semiconductors, we would have fantastic computers already.
it is a WHOLE nother story when we discuss physical systems that take MANY post docs and graduate students years to make properly (only once) and only work half of the time.

add to this the fact that these real devices are created using the most sophisticated techniques known to man, under the most rigorous and strict experimental conditions known to man....


what will take 50 years is the development of a method to mass produce any form of sophisticated nano architecture.
the real advances in solid state are not ultra cutting edge new shit.

its the old shit that is applied to the new:


single crystal, low defect density ZnO2 grown in AQUEOUS solution at 50 degree C at atmospheric pressure

Terahertz MEMS gold antennas for use as IR antennas (Eg IR solar cells)

>>1246352
>>1246352
>>1246352

good god.

thats wayyyyyyy more than the national average.


is that an RA or TA salary?


the national TA salary is something like $24k/year (including summer)

>>1247537

Actually, my friend is a grad student working in complexity theory (and he is a serious badass in his work). He says there are just so many things that remain unproven in classical computation that he seriously doubts quantum computer scientists can make significant theoretical progress. We can see this by the quick fizzling of interest after the explosion in the 80s.

Most importantly: there is NO proof, and may very well not be the case, that there are problems a quantum computer can do that a classical one cannot. There is no proof that a classical computer cannot model a quantum computer and run Shor's algorithm.

>>1247584
Now, that sound about right, at least for a decent physics school.

I'm 26, I've been out of college since I was 20. I'm starting over basically from ground zero, and have been accepted into a dual major program for this fall for Physics and EE (Electronics focus). My dream is to do some real work for something important - not just be a lab tech or maintenance jocky for some random lab or company. I've been studying (relearning) my math the past few months in preparation, and I plan to have a four year in Physics, a four year in EE, and a masters in one of em by the time I'm 31 or 32. Will I be able to get a job in a government (NASA or ESA) or emerging private space company? Or at some sort of important research, like LIGO or one of the accelerators? Were there people in your graduate classes and beyond who started this late and were still able to reach for their dreams?

Let's assume I hold a 3.5 or better average - do I have a chance?

I know this isn't Physics related but you've gone through the ranks in education, so I'm wondering if you've met any people like me in the course of your studies. I need some hope.

OP back,
>>1247584
>>1247633
Don't know what to tell you.

>>1247636
I see no reason why you couldn't. A few of the graduate students in my year are a few years older because they had mandatory civil service in their home countries.

I think you have a good chance. Good luck and don't give up your dream.

OP, you're the coolest guy in the world, you know that? I hope you're getting laid.

>>1247537
Many believe that no form of computation available in this universe can solve NP-hard problems in polynomial times.

>>1248611
Many believe in God, too. Prove it.

>>1248638
Too long and pointless to explain on a chan board, much more to a troll.

I HAVE A QUESTION MR PHD

As a fellow physics student, should I also get a PhD, or just a masters. I'd like to balance my desire to learn with my desire to make a decent wage, and so far undergrad physics has made learning fucking HARD

does P=NP?

>>1248704
Probably not, but we have no proof

what can you do as a physicist? only teach or research?

Is matter infinitely divisible? why or why not?

OP here, sorry for the recent neglect, haven't checked this in a while

>>1248582
Thank you, and I am
>>1248638
In fact, P = NP is one of the millenium problems, if you can prove it you get a million bucks. In fact, you get a million either way.

>>1248691
Fun fact, the average income for physics masters is higher than for physics PhDs. Then again, a lot of jobs require PhDs these days.

I say you feel it out.

>>1248704
Dunno. I actually kinda want to believe that it is. I have no reason to believe that it is, but it would be pretty neat. Additionally, as a physicist I am deeply puzzled how certain computational problems are so difficult for us to compute, but Mother Nature gets it done lickity split.

Of course, people will cry that natural processes are massively parallel, and I know that, but still.

>>1248750
No, in fact you can do all sorts of stuff. See >>1246592 where I talk about some of the jobs my fellow undergrads got.

>>1248763
No. There are elementary particles that as far as we can tell have no internal structure, i.e. they are point particles. Electrons, neutrinos and quarks fall into this category.

>>1248663
Moron.

>>1248773

^what is that?

Alright then, I'm going into college next year and I just want some input:

I only took up to sophomore year in High School, which didn't teach any sort of advanced anything.

I'm really interested in Physics, and want to one day get a Phd. in Quantum Physics, not sure exactly what yet.

Basically, I'm going to a community college next year and have thus far a shit formal education. However, I'm intelligent and can learn pretty damn well, so I'm planning on studying over the summer.

Right now I'm focusing on learning Calculus, and then taking Linear Algebra and Physics my freshman year.

Is there any particular area of study you would recommend, or any courses you think I should take?

>>1248794
I actually just answered that in the other thread.
See >>1248801

>>1248807
A good math background is really important for physics.

This is somewhere where our education system lets most students down. A lot of students will take all of the prerequisite math courses but somehow manage to not get any understanding out of them.

So, when you study, make sure you really try and understand /what/ you are doing and /why/, not just memorizing a bunch of algorithms for getting answers to questions.

For vector calc, I recommend Div Grad Curl and All That, which is available from some torrents online.

Linear Algebra is also really important. All of science is essentially linear algebra, so make sure you pay attention when things like eigenvectors come up because they will keep showing up.

And good luck. Physics is a lot of fun.

I plan on going into the field of acoustics. I've completed calc I and didn't find it too difficult, but I have no experience in physics. How difficult would you say the physics dealing with acoustics are?

>>1248826
I mean, all areas of physics are the same difficulty I would say. You can always dig deeper.

Acoustics is an interesting field I wish I knew more about. You will need to have a good background in calculus, especially multi variable.

A car made of diamonds crashes into a wall made of diamonds at 400rpm

WHAT DO YOU DO

>>1248850
pick up the pieces. Now go away

>>1248854
lol'd

>>1248840

Okay, thanks for doing this, you're awesome!

>>1248807

First and foremost:
1)Practice an insane amount of vector calculus. Know div, grad, laplacian, etc. in cartesian (duh), cylindrical, and spherical coordinates by heart. Have an intuition for what each term contributes and means. If you grok this, you are set for EM, classical mechanics, and a lot of quantum.

2) Know basic linear algebra fluently, i.e. solving matrices and writing them in new bases. Now you are set for quantum.

3) Quantum is a tool, not a "field" per se. Read Nature and Science to get interested in actual fields of research.

>>1248879
>grok
man I didn't know people still used that word

>>1248879 here. i didn't see >>1248823, but it appears we have consensus. know linear algebra and especially vector calc like your second language.

Another physics grad student here. Know your vector calc and linear algebra, cold. If you have time, do some complex analysis.

Also, I've heard that ILC is pretty much dead and nobody knows what the next big accelerator is going to be.

>>1248891
Yes. Do you have a synonym that connotes the same? Ironically, people have probably used that for 600 years.

>>1248879
>Know div, grad, laplacian ... in cylindrical and spherical coordinates by heart

Fuck that shit.

>>1248923
I just looked it up, I was curious.

Grok originated in 1961 in R. HEINLEIN's Stranger in Strange Land

>>1248781
>the average income for physics masters is higher than for physics PhDs

But I'm doing a Masters degree and I'm being constantly scoped for a Ph.D. Is this a bad sign?

>>1248935
I know. I was referring to any synonym you come up with. People would probably "still" be using it after 600 years, hence, the irony.

>>1248938
I mean, finish if you can. You will have a lot more opportunities with the PhD than with the masters.

In the US anyway, universities have an incentive to keep you on for longer and give you the PhD. It is sometimes easier to gain admission to a PhD program than a Master's program at the same university.

>>1248823
>>1248879

Thank you very much, both of you.

One last question, though:
How important do you think the Junior and Senior year of High School that I missed out on are in relation to my plan?

I was planning on learning the basics of Calculus this summer, then just taking linear Algebra first year in college, do you think it might be a better idea to take the Calculus course instead, so I have a more "formal" foundation, since I'm probably going to take higher levels of Calculus later on.

>>1248938

Disregard money
Acquire physics

If you wanted money you should have become an engineer.

>>1248954
I want both.

sadfrog.jpg

>>1248954
It's not a bad thing to want to better understand the universe and still be able to make it from day to day.

CC fag about to transfer into physics.

What was your favorite undergrad course? Most hated?


What should I expect? I'm raping Calc III right now with little trouble, taking Linear Algebra in the Fall. I took AP Physics (but it was only B, so it only exempts algebra-physics).

>>1248951
I don't think high school is that important in the big picture. You do need to be 'fluent' in lower mathematics: algebra, geometry, trig should be second nature.

Are you planning to take a calculus course this summer, or just work at it yourself? You should probably take a course unless you have friends who know calc well and can help you with tricky points.

>>1248927
Seriously, there are only like half a dozen "not obvious" terms to know. You save yourself so much time to be able to just dump out the laplacian in spherical from your head. Just take 5 minutes to review them then write them from memory like once a week. You'll have it in no time. It's literally the alphabet of mechanics.

>>1248993

Due to my... situation it's impossible for me to take a course this summer at any sort of college. However, I am going to download a textbook or two on it, as well as use khanacadamy/open MIT stuff to help me out.

My thinking is to just work through the book, if I can do that, I should know it well enough.

>>1249025
Yeah, that sounds okay. Stay serious and you should get through it fine.

OP here
>>1248991
My favorite course was an applications of classical physics course that covered everything from fluid dynamics, to elasticity to general relativity to plasma physics to stat mech to random processes to nonlinear optics. Everything.

Worst course? Don't really have one.

>>1249025
Just remember, whats important is not that you can crank out the answers, but that you understand. Learn such that you could explain stuff to your grandmother. Hell if you have a grandmother, try and explain calculus to her.

As far as calculus goes, I really kind of dig this book:

http://books.google.com/books?id=BrhBAAAAYAAJ&dq=calculus&pg=PR3#v=onepage&q&f=false

Free on Google books, its a very old text book, but its not as though calculus has changed. And it writes with the explicit purpose of getting you to understand what calculus is. Id suggest reading this first, then working through a more traditional textbook, I think it will help a lot.

>>1249047
>>1249048

Again, thank you both very much.

Whelp, off to spend the next couple months straight studying.

>>1249048
>>1249048

Book is no longer available on Google. Its only giving me snippets :/

>>1249064
Try: http://books.google.com/books?id=BrhBAAAAYAAJ

Should be a link to download on the right,

Otherwise, byline is

Calculus made easy by Silvanus Phillips Thompson

>>1249069
The beauty of that book is that its written in plain english. Its a fantastic read, actually quite fun to read.

>>1249025

You have no idea how often I hear the blissful optimism of "learning physics/math on your own out of a book", and you have no idea how often they come back after the summer having done little to nothing. I'm talking about Berkeley grad students here. seriously, take a class. Without the class, I guarantee you will do at best 40% of the courseload. It will be WAY too easy to give up on a problem you deem too hard without the discipline of a classroom.

What kind of stuff is important for linear algebra? I found what appears to be a decent textbook on the subject, but it's missing some stuff like Gauss-Jordan (which I happen to know already, because of wikipedia, but that covers all I know about solving systems of linear equations), LU decomposition, and some stuff on planes.

>>1249079
...and this is nothing personal. That's just how it is, especially since you don't know what "real" hard academic work is, there is a much larger incongruity between perceived ability and actual conceptual depth.

>>1249093
Yeah, I'm gonna have to agree with you there. It's like trying to learn to play an instrument with a book.

>>1249057

Heh. It seems I've totally forgotten about the fact the only experience I have with Trig is a Geometry class that barely grazed it.

Sorry, but could someone please tell me just how much (and what level) Calculus/Linear Algebra is used in a first-year Physics course at a shitty community college?

I can't imagine it using anything higher than Calc 1, which is pretty basic, but then again I have no Idea what kind of algebra is used. I would assume it's Matrix Algebra at its highest, but seeing as how I have no experience with this, it would be nice for some guidance.

Might not be enough time to learn Trig and Calc 1.

>>1249069
Ahh they blocked my Canadian IP.

No problem, FreeToView was sufficient to bypass the restriction.

>>1249088
I think the things to get out of linear algebra are (1) how mind knumbingly general linear algebra is (2) what eigenvectors and eigenvalues are, (3) what a trace and determinant are, (4) understand what unitary transformations are

a lot of the other stuff like Gauss Jordan, LU and that stuff is just algorithmic which you'll most likely use a computer for anyway. Futhermore, much more powerful computer routines exist. If thats your cup of tea, make sure you look at QR decompositions, and probably the most important, singular value decomposition.

>>1249099
Probably little to no linear algebra and calculus will be used in your intro physics course, but if you want to learn and appreciate the physics you should learn them.

>>1249093
>>1249098

Yeah... I would love to take a class, but there is no way that that is possible, whatsoever. I'm going to have to teach this shit to myself if I want to stay on track.

Luckily I have nothing to do at all this summer, so there is little distraction for me.

>>1249099
For the "calculus-based" physics series, it's just integral calculus. You solve basic no-brainer integrals.

>>1249117
That's if you're lucky. At my low-mid-tier school, the kids I TA for do no actual calculus-based problems in their 'calculus-based' class.

Read this OP and tell me if this small rocket could reach orbit if launched from it's balloon at an angle rather then straight up. What angle? my guess is 45degrees. How many orbits?

The implications of such a small simple rocket being able to place 3.5 pounds into orbit are obvious (Worlds first orbital dildo). Oh, and also I was thinking of recreating this rocket using Ammonium Percholate Composite Propellant since I can't figure out what they actually used and since APCP is within an amateurs grasp.

http://www.designation-systems.net/dusrm/app4/farside.html

>>1249117
...but of course you need to understand it well enough to set up the integral. Calculus 2 of the typical 3-part series is enough.

>>1249107
Cool. Next question: How important is differential equations? I didn't spend to much time studying for it during the semester, and I had to cram during the last week of classes. I did well, but I'm by no means fluent in it. Is it worthwhile to revisit it?

>>1249133
Sorry I'm going to bed soon so don't have the time to read the link right now, but I will say that I recently spent some time thinking about how an amateur could get a rocket into space and convinced myself, similarly to yourself that using balloons to get above most of the atmospheric drag was worthwhile to think about.

The problem then of course is in trying to get accuracy at launch.

I never did finish thinking it through, maybe your link will motive me, but I'm afraid not tonight.

>>1249142
Differential equations are the language of physics. Fortunately for you and me and everyone else in physics, there are really one a few equations that show up regularly. You should be familiar with the wave equation, and the heat equation to be certain. Dispersion and Schrodingers equation are just other versions of the heat equation. After that they tend to get somewhat specialized.

As long as you are familiar enough with methods for solving differential equations such that you know where to look them up if you need them, you should be alright.

>>1249133
Dude, the thing weighs a ton. Literally.

do sounds exist if nobody hears them?

>>1249169
Yes.

Alright boys and girls. Its been fun, but OP is going to go to bed. Thanks for keeping this thread relatively free of trolls, gives me some hope for /sci/

I might do another one of these again someday.

Good night.

your thoughts on the effect of the observer on collapsing the wave function. and has this actually been proven?

>>1249179

Thank you very much, this thread helped me quite a lot to get my first year in college sorted out.

>>1249169
hurrf durf sound waves still happen but they're just air vibrations till a brain turns them to sound. though i guess it depend on your definition of sound.

simple fucking answer, i'm tired of this question. it aint deep.

>>1249142
You need to solve differential equations, so study the whole subject. However there are pretty much only 2 techniques you need to master:

1) Separation of variables. if you're solving for a function of multiple variable, i.e. f(x,y), you assume it can be written as: f(x,y) = g(x)*h(y), then plug it in the DE and massage it.

2) Assuming the solution has a particular form. Most often solutions look like: f(x) = exp(k*x), then you plug this form into the DE and you get an equation for the k.

>>1249179
you should get a tripcode dude