/sci/ - Science & Math

How do you tie your tie?

are there more than 3 dimensions not including time?

>>1369742

<-------------------
Just like my buddy Erwin Schroedinger over there.

>>1369737
Are you Jewish?

>>1369748

More than 3 spatial dimensions? Nobody knows that for sure, I personally doubt there are any that we could interact with in any meaningful way. That's one of the many things the LHC wants to try and test the existence of.

What's the most important principle in physics?

Do you enjoy your work?

Do you understand the dead cat, Clive?

>>1369790

I love my work, I couldn't see myself doing anything else.

>>1369782

I'd say that the most important principle in physics is that nothing is sacred.

That means that no theory, no matter how expansive and complete, no matter how genius its creator, is immune to scrutiny and doubt.

>>1369752

No, not Jewish surprisingly.

>>1369797

Yes, I understand the dead cat.

Where do you work and do day to day?

>>1369820

I work in a laser lab at a major university, and what do I do day to day?

Drink beer, socialize at various bars, smoke weed, and best of all the career I love pays me to do it.

>>1369832

was it hard to reach your PhD?

were you in an advanced class during your high school?

>>1369737
Fucking magnets! How do they work? Seriously.

>>1369816
But you you can't really understand the physics without understanding the math, the math tells how it really works. Thats the real thing, the stories I give in class are just illustrative, they're like fables say to help give you a picture. Even i don't understand the dead cat. The math is how it really works.

>>1369844

I dont have my Ph.D. yet, however I was not in advanced classes in highschool. I did get a chance to go sit in on two introductory calculus and physics classes during the summer for a few years in highschool (most physics professors will let you sit in on their classes if you ask them first, and arent loud or obnoxious).

Reaching a Ph.D. is no cakewalk, but it's not what it seems to be. It's alot of research, which means alot of time spent in the lab tinkering with equipment till it works and gets the data you want. Then its alot of writing about that data and what it means. The good news is though you have anywhere from 3 to 7 years to do the writing and research.

All in all, I find it incredibly enjoyable.

>>1369848

The dead cat was actually a thought experiment proposed by Schroedinger to discredit the idea of simultaneous quantum states, i.e. the cat being alive and dead at the same time.

The math lends itself to the physical reality quite handily, actually. People have this misconception that Quantum Mechanics is too crazy to understand, when it really isn't.

If you would like, I can give you a very, very intuitive explanation of why we say the cat is both alive and dead at the same time.

What's your emphasis in physics' subjects? Obviously something to do with laser but what exactly?

>>1369869

I study the interactions of light particles and their environment, including matter and other particles of light.

>>1369866
I for one would like this intuitive explanation

Of your fellow physics Ph.D. students, which ones seem to be the most and least happy? That is, which subfields of physics seem more likely to cause enjoyment, and which are more likely to cause misery and burnout?

>>1369866
Please do.
Post a new thread about it.

>>1369886

Sure, pay attention:

Quantum behavior stems from a simple physical reality. Tiny things behave differently.

Think of trying to measure how big something is, like a basketball. You'd use a measuring tape.

Now think of trying to measure something like a fly, you'd have to use a microscope and some kind of reference for how big it is.

Now try thinking of measuring something impossibly small, like an atom or something around that size. At that point we don't have rulers small enough to measure these things, so we have to use light particles which have a small enough wavelength that they'll bounce back at us to measure how big things are at that size.

Normally this wouldn't be a problem, but keep reading and i'll explain why.

>>1369904

The problem with measuring an atom with a photon is that a photon has enough energy, or "is big enough" if that is more intuitive, that it actually changes the atom you are measuring it with.

A basketball doesn't move when you measure it with our best measuring stick (i.e. a photon), nor does a fly (not much at any rate), but an atom recoils away due to conservation of momentum.

Therefore we can only say where it was, not where it is now, because as soon as we try to see where it is now, which again involves using a photon, we have changed it yet again, and its off somewhere else.

It's alot like trying to find the soap in a bathtub with just your hands. You wrap your hands around it just for an instant before it slips away from you, and you have to go fumbling about to find it again, only to have it fly away from you.

How much time do you spend on 4chan?

>>1369926

Now here's where the cat comes in.

There were two main ideas about where particles were back when quantum mechanics was being formulated.

There was the Orthodox position (held by Einstein, Bohr, and a number of other very famous physicists), and there was the Copenhagen interpretation, held by other equally famous scientists.

The Orthodox position held that the particles were always somewhere, but we couldn't see them because we had to interact with them to notice they were there.

The Copenhagen interpretation stated that the act of measuring where a particle was forced the particle to "take a stand," so to speak, about its location.

Before and a while after the measurement took place, the particle was considered to be everywhere and nowhere at once, i.e. it was believed to be in all its possible positions at the same time until you measured it, forcing it to be in the place where you found it.

Stay tuned for more

>>1369945

Eventually experiment would suggest that the Copenhagen interpretation was the correct one, however the relevance of that is still hotly debated in the community.

What Schroedinger was saying about the cat, as a joke mind you, was that the cat tied to the quantum state of a particle (e.g. where the particle is, or how much energy it has), is also therefore in all possible configurations of alive and deadness at once. Only when you open the box, either killing or saving the cat, does the cat exist in one state or the other.

The mathematics of Quantum Mechanics is rather straightforward, and highly accurate, however don't let its interpretations be a substitute for rationality and intuition. There is an intuition at the quantum level.

>>1369932

Maybe an hour or two every two weeks or so. Just to keep up with the latest memes.

>>1369959
How much more Math do I need to mathematically understand the schrodinger equation and the basic particle quantum stuffs? I'm doing Differential Equation and Linear Alg right now and I think I'm doing okay.

>>1369978

That's essentially everything you need to know to understand how to solve the Schroedinger Equation.

The only thing you have left to learn is how to do Separation of Variables on a partial differential equation (almost all schroedinger equations, with the exception of the most basic and easiest examples are partial differential equations).

You should take a class on the Calculus of Complex Numbers as well, just so you know how to deal with ' i ' and solve complex valued equations.

Otherwise, you're well on your way :)

>>1369959
Thankyou for that kind anon.

Why is God fake?

>>1369986
okay, thanks for your great input!

>>1369996

You're welcome, it's one of the most common questions I get.

People shrug it off and chalk things up to "quantum wierdness" so they dont have to think about it, but if you actually mull it over there is a good degree of intuition involved. Things sorta behave as they ought to, given their bizarre environment.

>>1369857
>doesn't have a Ph.D. yet
>think he's a physicist

pff
There are like eighty other physics grad students here. Come back when you publish something.

What equation goes along with the cat?
What more can be said that can't be described with English?

>>1370014

Ah, you dispute the validity of my claim to the moniker "physicist".

You know that Michael Faraday, one of the greatest physicists to have ever lived, didn't even have an undergraduate degree? :p

>>1370032
That was in the early 1900's, when all the physicist in the world could fit in one auditorium.
Times have changed. Now you cant call yourself a physicist with out a degree.

But then again, if the title doesn't count, what have you done to call yourself a physicist? how many papers, OP? or will you say that a real scientist doesn't need to publish?

>>1369866
DO'H

You totally ruined the movie quote, but thanks though.

I was playing out the scene from A Serious Man with Prof. Gopnik and Clive.

philosophyfag here.

Did you get to study philosophy of physics? Do physicists respect philosophy (mainly metaphysics) or think it's all mumbo-jumbo?

>>1370061
Oh run along now.

>>1370061

I have a degree in physics. Therefore, according to your albeit contrived definition of physicist, I am a physicist.

I haven't published yet. Still working on my thesis.

What do you call someone who is a practitioner of physics?

Also, why are you so butthurt about whether or not I am a physicist? What have you published?

>>1370085
Two posters and two papers, one my undergrad thesis and one that came of lab experiment.
How does that feel?

>>1370077

I would say there are a few interesting ideas in philosophy have analogues in physics.

For example, the Quantum Zeno paradox is an analogue of the famous philosopher Zeno of Elea.

http://en.wikipedia.org/wiki/Zeno_of_Elea

Philosophy, at least for me, is something i occasionally use as a font for interesting or out of the box ideas, but other than that, it's just a curiosity.

Metaphysics I wouldn't exactly relegate to the realm of mumbojumbo, but I don't hold alot of stock in it.

>>1370101

Doesn't really feel like much to be honest, since I really don't care about your personal achievements, being that they have no direct or remotely indirect affect on me.

An undergrad thesis? Nice. Two semesters of course work in an undergraduate curriculum. I didn't do one of those, didn't really care to.

A paper on your lab work? Also nice. I built my own lab set up, tested it, collected data, and got into grad school on the basis of that experiment alone.

Again, why are you so obsessed with what I did?

>>1370101

Just call yourself and OP grad students for fucks sake. If you really work in the field for any length of time you'd have at least a few dozen peer-reviewed papers published by now (hundreds if you count conference proceedings).

>>1370103

Do you use ideas of physics to understand/explain other spheres of life like ethics or politics? Like an integral world view thing.

What do physicists think of mathematicians?

How much do you get paid doing academic research (also which country)?

Can you do crazy cool stuff like Tesla?

>>1370119
>>1370101

Shameless samefaggotry

>>1370124
S-stop it, Philosophy-san! He's going to look down on you!

>>1370116
Just trying to make the point that you really cant call yourself a physicist yet.
I don't think I can either, by the way.
You could be slightly more accurate and say ask a "physics grad student anything". A little respect for the ranks wont hurt anyone, right?

>>1370144
>>1370119
oops, samefag revealed.

>>1370144
You must be from Cleveland.

>>1370134
I like them physicists. I met a guy that was doing the Ph.D on the philosophy of quantum physics. Seemed interesting.

Also, he said I could ask anything.

>>1370149

No, not samefag. An actual nuclear physics PhD checking in.

>>1370124

I try to leave politics, ethics, and religion out of my work in Physics.

I don't like mixing things that generally espouse my own personal hatreds with things that I love :p

What do I think of mathematicians? They're quite smart, albeit a bit quirky and often sort of "out there". However I've taken *alot* of math courses, so I have a healthy dose of respect for them.

My research is in the United States, and I get payed pretty crappily as a graduate student, between 30 and 40K.

Can I do crazy cool stuff? I built a device to test the Faraday Rotation constant (Verdet Constant) of various materials for under 600 dollars using a 500mW green laser and a bunch of shit i built by hand.

Does that count as cool? It has lasers in it :D

>>1370116
OP, what was your experiment/how did you go about conducting it/etc? I love hearing about shit like this.

>>1370150

I'm living in Cleveland. Are you implying something?

HEY FAGS! I don't care if any of you have a fucking degree!
Answer my q
What equation goes along with the cat?
What more can be said that can't be described with English?
discus

>>1370170
Oh, no! Nothing at all. I hear Cleave-er-Cleveland is a great place!

Anything?

Well, I'll try to keep it in your ballpark. Assuming you have an affinity for History, would you say that pre-WWII Germany was the world's greatest scientific power at that time?

>>1370167

My experiment was to test the Verdet constant of a variety of materials, specifically water.

It's a relatively simple setup, you need a laser, and in my case, a pair of lenses to shrink the beam diameter down so it fits inside of your polarizing beam splitters. You then bounce half the beam off one polarizing beam splitter, through the water which was encased in a 0.1 Tesla 1 meter long solenoid magnet.

The polarization angle is rotated by a certain number of degrees, depending on the material through which it travels (water), the strength of the field, and the length of the magnet.

You then let the beam filter through another polarizer, and measure whats left after the last polarizer, which is the amount of light energy that got rotated by the magnetic field.

In short, lasers are kewl.

>>1370176

There isn't really an equation that says "this cat will be alive and dead at the same time." The best you are going to do is learning what the solution to the equation to the left means.

>>1370188
so here's one experiment done by an OP
so what's some of the experiments done by the other self proclaimed physics Ph.Ds?

>>1370207

I never claimed to have a Ph.D.

I don't have one. I did claim that I am a physicist, which is a pretty hard claim to refute being that I have both a degree and a career in physics. Call it what you will :p

>>1370207

My thesis was on particle correlations in a fixed target experiment at one of the US accelerators. I did my postdoc and published similar work at vastly different energies at one of the colliders in the US.

Off to bed.

>>1369926

That's the Heisenburg Uncertainty Principle is it not?

>>1370228

In a nutshell, yes. You cant know position AND momentum to infinite accuracy simultaneously, because the more you measure its position (by blasting it with a photon, sending it speeding off in some other direction), the more its momentum changes. Alternatively, the more you measure its momentum (again, by hitting it with a photon), the more its position is changed.

>>1370219
grad student

>>1370202
What is the equation asking in the first place? Is it something that can be translated into words? or only understood with more numbers?

>>1370176
its fucking
sqrt(2)/2|alive>+sqrt(2)/2|dead>

>>1370241
>>1370241

http://www.merriam-webster.com/dictionary/physicist

Physicist.

>>1370261
owned. Unless of course he wants to argue that you aren't yet a specialist because you haven't gotten your phD...but fuck that noise you built a fucking awesome experiment. PHYSICIST, IT IS.

>>1370246

The solution to that equation states that the state in which the system is in is given by the potential energy of the system (given by the U variable) plus the kinetic energy (all that wierd looking shit to the left of the plus sign). The system state is denoted by the upright Pitchfork looking variable, known as the greek letter "Psi". The little x's you see let you know that these variables are all in terms of position (position is often denoted by the letter x).

>>1370246

btw, this is a simpification -- that's the one-dimensional time-independent equation. The general form is a little more complicated. In general it tells you how a wave (represented by the greek symbol psi) evolves over space and time.

>>1370294

Yeah, this poster is correct. I didn't want to put the Time dependent, three dimensional Schroedinger Equation in, because it's like a total of 6 symbols and it looks much simpler than it really is.

>>1370241
phd here, stfu you miserable cunt.

Quick question... How often do you interact with Mathematicians in your field... Because i'm very interested in physics but i love math as well...

Explain this, please

>>1370349
I have no explanation for the awful socks they're wearing!

>>1370343

I interact with mathematicians a great deal, for two reasons:

A.) friendship. I am friends with lots of mathematicians.

B.) peer review. I often need an outside set of eyes, especially one mathematically inclined, to check my work for sanity's sake.

Physics and math go hand in hand. I do both, if you like physics and math, you should too.

>>1370366
So you're a double major? Sorry for the stupid questions... I've been out of school for a while now and i can't make up my damn mind over what i want to do.

>>1370294
To try and teach me the mathematics, though i thank you for the effort, is futile. I am still in low level math in terms of you guys. Sophomore in h.s starting precalc and physics next year.
I would rather just try and hear your explanation of what this equation is asking? And what the solution is answering.
The cats is alive and dead at this present state of time. How can an equation go into anymore detail besides statistics?

>>1370349
see >>1369848

>>1370380

Funny story really. I started out as just a physics major in undergrad. Then I double majored in physics/math for a bit, took all but two of the pure math classes available, then found out they wanted to add an additional 12 hours of coursework in upper division bullshit liberal arts to my degree in order to double major, and I wanted to graduate (it had been 5 years), so I said fuck that noise and just stuck with the single physics major, despite the fact that I have taken more math than most math majors.

>>1370382

Equations rarely, if ever, ask questions. *People* ask questions, and then come up with equations that have solutions that help answer their questions.

In this case, the question people asked was "how do things roughly the same size as atoms change, behave, and interact in time."

>>1370393

I'm pretty sure all of the extra math you took is coming in handy though.

But yeah... seriously fuck all of the liberal arts bullshit... a friend of mine went IIT and they made him choose between going taking women's studies or black studies... I forgot which one he took but he dreaded having to sit through that.

>>1370428
What's wrong with women/black studies?

>>1370428

That's pretty much how I feel about it.

Undergraduate school sucked for the soul reason that I was forced through that liberal arts crap. I hated every second of it.

Oh yeah and chemistry, i hated that too. My professors were assholes. :-/

>>1370438

Nothing wrong with them really, he just felt they were irrelevant to his course of study. (He's a civil engineer now)

>>1370442
Funny... and I love chemistry as well. You are right about Chemistry professors being douchebags though... i had one bitch call me a psychopath. You would think a chemistry professor would know that adding ethanol to a coke would be making a rum and coke. Cunt.

>>1370404
Thanks for putting up with the questions.
*looks at clock* 2:30? Off to bed to ponder.
NIGHTS EVERY1!

>>1370465

May the time derivative of momentum be with you, always.

Average person here, is physics something anyone can get into with enough effort, or is it beyond the grasp of the average individual?

>>1370512

I dont feel there is anything special about me, and I do physics for a living, and I do it pretty damn well too.

I feel it's something that with enough effort, anyone can get into.

Serious question:

If the Sun's core is helium/hydrogen, .. What prevents the iron from accumulating?.. especially considering the strong gravity.

-Satellite photos show plenty of iron in the Sun.

>>1370555
Nothing.
Absolutely nothing.

Iron accumulates.
Heavier atoms begin to form.
Eventually the sun will reach an unstable balance and go supernova.

>>1370555

That's an easy question. In small enough amounts, like the amount in our sun, the iron will be pushed outwards by the nuclear pressure of the core of the Sun.

>>1370555
Not OP, but iron fusion does not occur till much later in a star's lifetime, and only if it is sufficiently massive to fuse whatever the precursors are, I want to say carbon. Also alpha processes can create iron. But the sun is not yet producing iron, what iron is there is probably just a contaminant from the sun's formation.

>>1370565

The sun is not nearly massive enough to start fusing silicon into iron. Hence it will not go supernova.

The contaminant theory is a valid one, and as stated before, alpha radiation can form iron, as can the intense amount of neutron bombardment in the core, albeit in very small quantities.

>>1370560
The sun is a low mass star. Also. The smaller atoms still need to fuse to produce iron. It simply does not have enough mass or density to fuse iron.

Your point is invalid.

Why are there so many commercials featuring skinny black women with curly hair strands?

How large does a star have to be to go supernova? Is there an absolute minimum size?

>>1370618

Around 10 times the size of our Sun will often result in a supernova. Nobody knows the exact mass, we dont have enough physics for that yet :)

>>1370618
No one knows for sure, approximations range greatly, but I recall something on the order of 4 solar magnitudes. As in 4 times the mass of our sun. I'll check that for you right now.

>>1370622
>>1370620
5 seconds on wikipedia and the latest I've seen is now 9 solar masses. But again, this is a very rough estimate.

How does the Fork Levitate?

>>1370594
Because most commercials are directed by gay men who want to use just skinny white boys, but have to use women too and are instructed to expand the target demographic to include blacks, and curly hair is considered ethnic.

Thank you, also how large does a planet have to be in order to be a star? I remember vaguely hearing that Jupiter was a failed star and that something with 70-80 times the mass of jupiter was required, but was this accurate?

>>1370655
Really dude, all of these answers are on wikipedia. It'll take you like 10 seconds to find them and you'll probably learn other things on the way.

that fork isn't on Wikipedia. 0_0

>>1370668
It is not the fork that floats.

What does the proton having a smaller size mean for physics? As in, what are the largest accepted theories that would change?

>>1370694
I won't be able to tell you with any certainty till next semester (when I do quantum) but I understand this should have some kind of ramifications in quantum theory. Whether they are big or small I don't yet know.

Is FTL travel possible?

>>1370712
Is there a higher being?

I find it very difficult to believe that iron can float on top of hydrogen/helium and not accumulate at the core. Iron is all over the Sun and concentration increases as we get closer to the "surface". In addition, there was a paper written by a scientist proposing the possibility of a liquid iron core Sun (with plasma surrounding). Looking further into this issue I have found it may be possible to explain helium production based on LENR principles and corona heating via electric z-pinch effect. Are you familiar with the electric universe model?

>>1369737

Is Schrodinger your favorite scientist? I feel so unusual being the only person among my science mates that admires this individual.

>>1370715
I don't believe there is

>>1370740

It's a three way tie between Schroedinger, Heisenberg, and Feynman.

>>1370724

Whether you believe it or not is irrelevant, people who have studied this much more than you have know things you dont about stuff like photopressure and thermodynamics.

Why does your research suck?

is the world of quantum mechanics "discrete" because the eigenvalues of the operators representing observables (many of them) are discrete?


I ask this because the mathematics used in quantum mechanics is the same that is used in classical electromagnetism and engineering.


laplaces equation in spherical coordinates has associated Legendre polynomial solutions in spherical coordinates (spherical harmonics)


the full H-atom electronic wavefunction is just a product of the solutions of the separated eigenvalue equations.
my question is:


is it discrete because the energy spectrum is discrete, or is it discrete because the actual eigenstates themselves are represented by discrete kets (which can, themselves, be expanded in any complete orthonormal basis)

>>1370791
I am not OP, OP is a fag.

No, actually the world of quantum mechanics is discrete because eigenstates are not continuous in some limits. Since eigenstates are essentially orthogonal, applying an operator doesn't 'make' them discrete.

If you are for instance doing the Harmonic Oscillator, then you will quickly see that only a few solutions turn out to be correct solution. You go from only continuous equations, to discrete. because if we would keep continuity for, say, the energy levels. It would mean our solution go to infinity, and hence become unphysical. It is the great work of planck, who should all energy is quantized.

>>1370900


yeah, I can tell you are not a physicist.


1) the operator itself defines the space in which the solutions live.

you are working with the 1d harmonic oscillator or a decoupled Nd harmonic oscillator?

solutions are hermite polynomials with eigenvalues hbar(n+1/2)
but at the same time:


the heat equation can be solved in a fourier basis or a basis of legendre polynomials (associated legendre functions, which are spherical harmonics when you change coordinates)


functional analysis and the theory of partial differential equations has methods that are completely independent of the physics of the situation and what they imply.
the wavefunction of a system is almost never measured, and the implications of quantum mechanics (The basic, historical, fundamental implications) have little to do with the eigenstates themselves.


it is the energy. the eigenvalues.
and remember, all of this is strange because:


E<V

if the speed of life was surpassed, wouldnt that object travel forward in time and not the preconceived backwards