# If anyone wants an update on my research, I got one



## Nightmaker81 (Aug 17, 2013)

Recently presented it. 

I'm not going into the nitty gritty details, but I work with graphene in condensed matter. My basic goal is to use graphene as a viable semiconductor through a chemical process. In the past few months 

I fixed our lab's CCD detector: 
http://i.imgur.com/bgDsuUA.jpg

Assembled an optics setup: 
http://i.imgur.com/TEg2fzv.jpg

And designed two of our chambers: 
(This is our smaller chamber): 
http://i.imgur.com/8tkmk6Q.jpg

Bigger NASA chamber(not 100% complete but very close): 
http://i.imgur.com/Xp3orLc.jpg

The reason we have these chambers is because 2D materials like graphene are very prone to surface contaminants because of their 2D like nature. Ultra HIgh vacuum minimizes a lot of those contaminants . It's all setup for getting data and analyzing it and trying to get a paper out. 

Prof was happy because I really tried to produce results for the lab and when I presented I think it also made him look good being his student lol.

My goal is to get a PhD in astrophysics and I'll be applying to programs soon. Hoping to use this as as a nice jumpstart into a grad program


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## Nightmaker81 (Aug 17, 2013)

Damn no one cares


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## Amy (Jan 15, 2015)

That's awesome! Congratulations!!!!!!


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## Velcorn (Feb 15, 2016)

It just seems a lot of stuff simply drowns in the figurative sea of posts on here or on the Internet in general. It might also be hard for people that are not at all familiar with your work to apreciate it simply because of the lack of knowledge on the matter.


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## Shinsei (May 9, 2016)

Your getting a Ph.D, damn where are you up to? Are doing your masters now?


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## Nightmaker81 (Aug 17, 2013)

Velcorn said:


> It just seems a lot of stuff simply drowns in the figurative sea of posts on here or on the Internet in general. It might also be hard for people that are not at all familiar with your work to apreciate it simply because of the lack of knowledge on the matter.


I can answer questions if anyone has any 



Shinsei said:


> Your getting a Ph.D, damn where are you up to? Are doing your masters now?


Nah not in a masters program, but been working in my research lab for the past year. Going to apply to PhD programs to get into experimental astrophysics


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## Shinsei (May 9, 2016)

Nightmaker81 said:


> I can answer questions if anyone has any
> 
> 
> 
> Nah not in a masters program, but been working in my research lab for the past year. Going to apply to PhD programs to get into experimental astrophysics


So wait I thought you had to do a Masters first then Ph.D ? Huh i suppose if you were doing research you can just go into PH.D. 
So what made you decide on experimental?l, Astrophysics was one of my interests but i think that is unlikely for me haha.


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## Nightmaker81 (Aug 17, 2013)

Shinsei said:


> So wait I thought you had to do a Masters first then Ph.D ? Huh i suppose if you were doing research you can just go into PH.D.
> So what made you decide on experimental?l, Astrophysics was one of my interests but i think that is unlikely for me haha.


I mean yeah you do, but with PhD programs the masters is sort of included in the package. Usually you come in as a PhD student and commit 5 to 6 years, and then take a candidacy exam around 2-3 years in. That let's you become a PhD candidate and focus on your dissertation, and at this point you "earn" a masters. From there you work on your dissertation/research and get a PhD

I chose experiment vs theory, because I'm not that great at theory. I can definitely keep up with concepts, but I don't have the natural talent some theorists have to really do extremely well in the field. My skills are more experimental, since I worked in an experimental condensed matter lab, and my math/physics skills are good enough that I can definitely keep up with the higher end theory, but may not develop anything new in terms of theory


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## Surreal Snake (Nov 17, 2009)

Sounds like you're getting some results well done


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## Shinsei (May 9, 2016)

Nightmaker81 said:


> I mean yeah you do, but with PhD programs the masters is sort of included in the package. Usually you come in as a PhD student and commit 5 to 6 years, and then take a candidacy exam around 2-3 years in. That let's you become a PhD candidate and focus on your dissertation, and at this point you "earn" a masters. From there you work on your dissertation/research and get a PhD
> 
> I chose experiment vs theory, because I'm not that great at theory. I can definitely keep up with concepts, but I don't have the natural talent some theorists have to really do extremely well in the field. My skills are more experimental, since I worked in an experimental condensed matter lab, and my math/physics skills are good enough that I can definitely keep up with the higher end theory, but may not develop anything new in terms of theory


Ahh rightio that makes more sense hmm i've never seen that package, its seems like it would work really well, So I am guessing you are still doing undergrad?
What are your research interests?


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## Communal Soap (Jul 6, 2014)

Nightmaker81 said:


> My goal is to get a PhD in astrophysics and I'll be applying to programs soon. Hoping to use this as as a nice jumpstart into a grad program


Wow! Go for it, my sister just defended her dissertation in the same field. Do you have any idea what you want to do after that? Is being a career scientist something that appeals to you? My understanding is that it's incredibly stressful and consuming with the constant competition for grants.


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## Nightmaker81 (Aug 17, 2013)

Shinsei said:


> Ahh rightio that makes more sense hmm i've never seen that package, its seems like it would work really well, So I am guessing you are still doing undergrad?
> What are your research interests?


I definitely want to do experimental cosmology, hopefully observational. I've been considering a lot of the University of California schools, Rutgers, a few midwest schools and one of my professors said I have a shot at Columbia, but that's going to be really competitive


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## Nightmaker81 (Aug 17, 2013)

Communal Soap said:


> Wow! Go for it, my sister just defended her dissertation in the same field. Do you have any idea what you want to do after that? Is being a career scientist something that appeals to you? My understanding is that it's incredibly stressful and consuming with the constant competition for grants.


Oh nice! Do you know what her subfield is in astro(did she do planetary astronomy, cosmology, galactic, extra galactic etc)

I want to go into industry and work at NASA. After that I want to apply to become an astronaut


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## Communal Soap (Jul 6, 2014)

Nightmaker81 said:


> Oh nice! Do you know what her subfield is in astro(did she do planetary astronomy, cosmology, galactic, extra galactic etc)
> 
> I want to go into industry and work at NASA. After that I want to apply to become an astronaut


Her work was on extraterrestrial water ice. Her department was engineering physics but I'm assuming that's the same thing as experimental astrophysics as far as research and career opportunities are concerned but I'd guess her course work was easier than yours will be.

She had an offer from NASA but turned it down because she realized that she didn't actually want to be a research scientist. Do they generally pick scientists? I thought most astronauts were from a military background.


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## Nightmaker81 (Aug 17, 2013)

Communal Soap said:


> Her work was on extraterrestrial water ice. Her department was engineering physics but I'm assuming that's the same thing as experimental astrophysics as far as research and career opportunities are concerned but I'd guess her course work was easier than yours will be.
> 
> She had an offer from NASA but turned it down because she realized that she didn't actually want to be a research scientist. Do they generally pick scientists? I thought most astronauts were from a military background.


It used to be particularly in the Apollo days. During those days space was a complete unknown so they wanted people who were used to venturing the unknown IE: Test pilots from the Air Force/Navy

Now things changed a bit: 
https://en.wikipedia.org/wiki/Mission_Specialist

Mission specialists make about 60% of the flight. They're the people who focus on the actual research on the ISS and places like that. Space missions nowadays are much more research heavy and are different from the 60s in the fact that all we wanted to do was actually make it up into space so people who have a strong academic background are very favored. 

Military personal who are test pilots are still chosen to be commanders/pilots but mission specialists are chosen a lot more now and are picked to do a lot of the heavy research up there


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## HAL (May 10, 2014)

I would still suspect they'd go for military types to be honest.

They're like super healthy trained monkeys.

Train them to go to space, push the right buttons on the machinery, follow every protocol to the letter, etc.

Meanwhile the science bunch analyse new data from ground level, like this legend.










I know if I wanted to go into astrophysics, I'd be more inclined to expect a career on the ground looking at data from space telescopes, asteroid landers and the likes, from a comfy seat in an office somewhere.


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## Nightmaker81 (Aug 17, 2013)

HAL said:


> I would still suspect they'd go for military types to be honest.
> 
> They're like super healthy trained monkeys.
> 
> ...


There were plenty of scientists who were non military: 
Payload Specialist Astronaut Bio: Loren W. Acton
Astronaut Bio: Joseph P. Allen
Astronaut Bio: Clayton C. Anderson (01/2013)
Astronaut Bio: Jay Apt 06/1997
Astronaut Bio: Ellen Baker (01/2012)

Point is list goes on and most NASA missions are more civilian than military candidates nowadays. Science knowledge is huge, because what if something wrong goes with the electronics on the ISS and someone needs advanced circuit knowledge to manually fix it, or what if they are observing something that has a very short span to take the data. With the way time dilation works in the ISS, the people on the ground are going to get the feed or information later in their rest frame. There's a lot of advantages of having people strong in science being up there and a lot of scientists in science fields have been chosen for that reason. 

Plus in terms of athletics I'm not that worried. I run a 5:30 mile, and I have a very strict diet. I keep up on my health because I know it's very important to becoming an astronaut and I'm very dedicated to this dream


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## HAL (May 10, 2014)

Nightmaker81 said:


> I'm very dedicated to this dream


In which case, good luck!

:happy:


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## Nightmaker81 (Aug 17, 2013)

HAL said:


> In which case, good luck!
> 
> :happy:


Thanks man


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## Nightmaker81 (Aug 17, 2013)

Finished NASA chamber: 
http://i.imgur.com/bkaNAdb.jpg


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## Mick Travis (Aug 18, 2016)

@Nightmaker81

Thank you for relentlessly perusing efficiency. People like you make my world possible and my dreams viable.


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## angelfish (Feb 17, 2011)

Really cool stuff - way over my head - but congratulations on all your hard work and good luck with applications.


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## Nightmaker81 (Aug 17, 2013)

My most recent presentation of my research!(Note: I was exhausted when the pic was taken)

http://i.imgur.com/Pm1fQg7.png


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## ae1905 (Jun 7, 2014)

not related to your research but an interesting application of graphene, nevertheless:

https://www.engadget.com/2016/09/20/graphene-therapy-spinal-cord-injury/

can you speculate what it is about graphene ribbons that allow the body to repair spinal cord tissues? 

my guess is it works because graphene is made of carbon (like life), graphene is electrically conducting (and can transmit spinal electrical signals), graphene ribbons are very small (even smaller than cells) and stiff (and can act as scaffoldiing around which new tissue can form)


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## Nightmaker81 (Aug 17, 2013)

ae1905 said:


> not related to your research but an interesting application of graphene, nevertheless:
> 
> https://www.engadget.com/2016/09/20/graphene-therapy-spinal-cord-injury/
> 
> ...


i
Yeah it's probably tied to the the strength and conductivity of graphene. Graphene is very unique in the fact that it has a zero band gap.

Because electrons are fermions and because they are anti-symmetric under exchange, they can't live in the same quantum state(as opposed to bosons). So the electrons want to go to the lowest energy state, but instead all packing into the same stage, build a sea of electrons, and the Fermi level is the highest band of the sea of electrons. Only electrons near the Fermi level can be electrically conductive, however the zero band gap give us a way around that. Because of the nature of that band gap, all the electrons don't necessarily have to be in the top layer of the Fermi Sea and electrons that are further away from the Fermi energy can be conductive.

So graphene acts as a material that's really strong and can act more of a metal than actual metals themselves


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## ae1905 (Jun 7, 2014)

*Silkworms Spin Super-Silk After Eating Carbon Nanotubes and Graphene*

The strong, conductive material could be used for wearable electronics and medical implants, researchers say 


By Prachi Patel, Chemical & Engineering News on October 9, 2016 









_Credit: WIKIMEDIA COMMONS_ Silk—the stuff of lustrous, glamorous clothing—is very strong. Researchers now report a clever way to make the gossamer threads even stronger and tougher: by feeding silkworms graphene or single-walled carbon nanotubes (_Nano Lett._ 2016, DOI: 10.1021/acs.nanolett.6b03597). The reinforced silk produced by the silkworms could be used in applications such as durable protective fabrics, biodegradable medical implants, and ecofriendly wearable electronics, they say.

Researchers have previously added dyes, antimicrobial agents, conductive polymers, and nanoparticles to silk—either by treating spun silk with the additives or, in some cases, by directly feeding the additives to silkworms. Silkworms, the larvae of mulberry-eating silk moths, spin their threads from a solution of silk protein produced in their salivary glands.

To make carbon-reinforced silk, Yingying Zhang and her colleagues at Tsinghua University fed the worms mulberry leaves sprayed with aqueous solutions containing 0.2% by weight of either carbon nanotubes or graphene and then collected the silk after the worms spun their cocoons, as is done in standard silk production. Treating already spun silk would require dissolving the nanomaterials in toxic chemical solvents and applying those to the silk, so the feeding method is simpler and more environmentally friendly.

In contrast to regular silk, the carbon-enhanced silks are twice as tough and can withstand at least 50% higher stress before breaking. The team heated the silk fibers at 1,050 °C to carbonize the silk protein and then studied their conductivity and structure. The modified silks conduct electricity, unlike regular silk. Raman spectroscopy and electron microscopy imaging showed that the carbon-enhanced silk fibers had a more ordered crystal structure due to the incorporated nanomaterials.

Some questions remain. One is exactly how the silkworms incorporate the nanomaterials in their silk. Another is what percentage of the nanomaterials eaten by the worms make it into the silk instead of being excreted or otherwise metabolized. The carbon materials are not visible in the cross sections of the silk threads, perhaps because the nanoparticle content is low, Zhang says. Answering these questions might be a task for biologists, she adds.

Polymer chemist Qing Shen at Donghua University reported similar work in 2014 using 30-nm-wide multiwalled carbon nanotubes, which also increased the silk fibers’ strength and toughness (_Mater. Sci. Eng._, C 2014, DOI:10.1016/j.msec.2013.09.041). Zhang says that the smaller, 1- to 2-nm-wide single-walled nanotubes her team uses “are more suitable for incorporation into the crystalline structures of silk protein.”

This work provides an “easy way to produce high-strength silk fibers on a large scale,” says materials scientist Yaopeng Zhang of Donghua University, who has fed titanium dioxide nanoparticles to silkworms to create superstrong silk resistant to ultraviolet degradation. The electrical conductivity of the carbon-reinforced silk might make it suitable for sensors embedded in smart textiles and to read nerve signals, he says.


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## Nightmaker81 (Aug 17, 2013)

By the way guys, I got the results from my presentation. I was very happy with them and gave me a nice boost during these past few stressful weeks: 
http://i.imgur.com/160xOj8.png
http://i.imgur.com/w6Dbo25.png
http://i.imgur.com/ZdtwT9F.png


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## HAL (May 10, 2014)

Nightmaker81 said:


> I chose experiment vs theory


I missed this before.

As a member of the rival clan, I feel it my duty to show you this fantastic meme I saw a few days ago:


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## ae1905 (Jun 7, 2014)

*Six amazing uses for the wonder material graphene*

*An aerogel so light, it can perch on top of a flower.*


   

Inhabitat 4h ago in Green 





_By Cat DiStasio_
Graphene is a super-strong, ultra-lightweight material that's led to scores of technological innovations in recent years. It consists of bonded carbon atoms formed into sheets that measure just one atom thick. The material's strength to weight ratio makes it ideal for all sorts of applications ranging from desalination filters that produce clean drinking water to batteries that charge up in seconds, and even next-gen LED bulbs. Graphene is even being used to make solar cells produce electricity in the rain, leading us to believe the most amazing graphene-based gadgets have yet to come.




*Making seawater drinkable*









Around the world, there's a major push for developing more efficient ways to turn saltwater into clean drinking water. Enter this atom-thick graphene filter, which Lockheed Martin found could reduce the amount of energy needed for the desalination process. The filtering material, dubbed Perforene, was originally patented for cleaning up oil spills. However, the company realized it could also serve other purposes. Because the filter is only one atom thick, saltwater flows through it without excess pressure - and since the holes in the filter are just 100 nanometers in diameter, they're just large enough for water molecules to squeeze through, but too small to allow salt particles to pass. This results in a desalination filter that cuts energy usage by 20 percent, making it more environmentally friendly and better suited for use in regions where electricity is as scarce as clean water.
*Super fast-charging batteries*









Today's rechargeable batteries tend to lose charge capacity over time - however, researcher Han Lin at Australia's Swinburne University created a battery with a graphene supercapacitor that can be used time and time again without any loss in performance -- and it charges up in mere seconds. Lin used a 3D printer to build sheets of graphene for his energy storage device, which could one day replace the lithium-based batteries in smartphones, tablets and even electric cars. Graphene gives this new battery a major edge, beating out traditional batteries in charging time, lifespan and also environmental impact.
*Solar power in the rain*









Scientists from Yunnan Normal University and the Ocean University of China used graphene to develop a novel solar panel that is able to generate electricity in the rain. A layer of graphene over the top of the solar cells generates energy as it reacts with naturally occurring salts in rainwater. The solar cells have an efficiency rate of around 6.5 percent, which isn't much, but with improved efficiency, rain power could become a real thing in places where the weather isn't exactly ripe for traditional solar cells.
*Super efficient lightbulbs*









The University of Manchester touts itself as the "Home of Graphene," because it was the first place to create graphene sheets back in 2004. Fast-forward to 2015 and a research team at the university created a dimmable, filament-shaped LED coated in graphene that uses 10 percent less energy than existing LED bulbs. The newer, better, longer-lasting LED went on sale in the United Kingdom shortly after, selling at a lower price than many competing products. The graphene bulb also made history as the first commercially available product containing the now-famous carbon allotrope.
*The world's lightest material*









Scientists are forever working to develop materials that are even more lightweight than ever, and in 2013, a team of Chinese researchers created a sponge-like material using graphene that earned the title of world's lightest material. Fusing freeze-dried carbon with graphene oxide, the Zhejiang University team produced what they dubbed Graphene Aerogel, a spongy solid material that weighs just .16 milligrams per cubic centimeter. The carbon-based sponge is incredibly flexible and is also capable of absorbing oil by impressive quantities. The team reports that the sponge can soak up 900 times its own weight, which means it could be used in the future to clean up oil spills. Best of all, due to the sponge's flexibility, both the oil and the sponge could be recycled, making it a sustainable solution to a practical problem.
*Paper 10 times stronger than steel*









Paper is notoriously fragile, especially in sheet form. It tears easily and even just a few drops of water can render it essentially useless for its intended purposes. Five years ago, a team of researchers at the University of Technology in Sydney developed a graphene-based paper than is 10 times stronger than steel. The durable nano paper, composed of processed and pressed graphite is flexible, 100% recyclable, conductive and durable and thin enough to be used in countless industries.


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## HAL (May 10, 2014)

Nightmaker81 said:


> I chose experiment vs theory,


Seeing as my last meme was brutally ignored, I feel compelled to repeat the whole process with an even better one I've just stumbled across on facebook.


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## Nightmaker81 (Aug 17, 2013)

HAL said:


> Seeing as my last meme was brutally ignored, I feel compelled to repeat the whole process with an even better one I've just stumbled across on facebook.


I mean dude, I'm happy you're in a degree program, but you're not a theorist unless you're doing actual theory. That includes having a thesis topic and really being on the cutting mastery of linear algebra, complex analysis, partial diff EQ as math subjects, along with a mastery of the physics behind whatever you're researching. A "theoretical" physics degree is just a physics degree, and it's something I've done. Ultimately what decides a theorist vs experimental is the research you do. It's cool you have ambitions but you're not actually a theorist unless you're in a theory research group doing theory on a subject that still has to be developed


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## Nightmaker81 (Aug 17, 2013)

And before you get defensive, I'm not trying to be insulting, but it does take a certain level of mastery of physics to be even dip into the basics of theory. If you truly are a theorist, you can answer this question. This is a really easy pertubation theory question. 

_ Two particles (same mass but not identical) are confined in a one-dimensionalsquare well, so that −L/2 < xi < L/2. (a) What are the energy eigenstatesin position representation and their eigenvalues? (b) A perturbationis added:H0 = g δ(x1)δ(x2). Use perturbation theory to compute the first-order shift in the energies ofall states for which ni = 1, 2, 3.

_The hamiltonian is two delta functions localizing x1 and x2. This is really easy for me to solve, and even at my level I'm nowhere near the capability of theory, because it's that hard, and you have to earn the ability to call yourself a theorist


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## HAL (May 10, 2014)

Nightmaker81 said:


> And before you get defensive, I'm not trying to be insulting, but it does take a certain level of mastery of physics to be even dip into the basics of theory. If you truly are a theorist, you can answer this question. This is a really easy pertubation theory question.
> 
> _ Two particles (same mass but not identical) are confined in a one-dimensionalsquare well, so that −L/2 < xi < L/2. (a) What are the energy eigenstatesin position representation and their eigenvalues? (b) A perturbationis added:H0 = g δ(x1)δ(x2). Use perturbation theory to compute the first-order shift in the energies ofall states for which ni = 1, 2, 3.
> 
> _The hamiltonian is two delta functions localizing x1 and x2. This is really easy for me to solve, and even at my level I'm nowhere near the capability of theory, because it's that hard, and you have to earn the ability to call yourself a theorist


Mate all physics degrees are not equal.

My university offers three routes: astro, theory and standard physics.

I chose theory. When I graduate I will have a degree in theoretical physics. I will have taken the route through university that exposes me to as much of a theoretical and mathematical basis as possible relating to all natural physical systems in the world. To do this, my course avoids all modules relating to practical experimentation (I haven't entered a lab for almost 3 years) and astrophysics (I haven't done _any_). This is because I'm doing a theoretical physics degree, not any other kind.

Compare these lists, particularly the compulsory modules in earlier years and the variety of optional modules in later years:
PHYSICS
THEORETICAL PHYSICS
ASTROPHYSICS

Now tell me you think all physics degrees are just physics degrees.

I suppose you think engineering is 'just engineering' too, regardless of whether it's chemical, mechanical or electrical...

Advanced quantum mechanics is open to most students because it's such a major area of physics. There are experimental physics students in my class too. We're covering perturbation theory in the next week or so.

I'm also doing Advanced Fluid Dynamics, Geophysical Fluid Dynamics, Linear and Non-Linear Waves, Topology, and Coding Theory (which provides a basis for understanding quantum computation). All of these are unavailable to astrophysics and standard physics students. If I decide to carry on to the Master's year it only gets even more specialised.

Do you know why? Here's the first sentence on the wikepedia explanation of theoretical physics:



> Theoretical physics is a branch of physics which employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena.


This is what I'm learning to do. It isn't all the magical string theory five-million-dimension gravity space-time Einstein malarkey people think it is. It's simply applying as much maths as possible to the real world, more-so than any other physics route. And one does not need to be a researcher or at the cutting edge to be able to categorise themselves as a specialist in their area. If I walk into a job where I need to apply specific theoretical physics knowledge every day, or come up with a mathematical description of a real-world problem for an employer or entrepreneur who doesn't have the education to do it themselves, _even though I'm not actually creating any new science_, I'll still be doing theoretical physics. I am training to be a theoretical physicist. Not any other kind. Just like you're well on the way to being an experimental physicist (in fact I think you've already achieved that status, which is awesome), and you would be even if your work wasn't in anything new or cutting edge. 

Anyway my knowledge on any given subject is hardly relevant... You just need to learn to take a joke..!

I actually think experimental physics is great. The dudes at CERN, LIGO, the Tokamak, etc, or even dudes like yourself, are doing really cool stuff that I simply can't because I'm rubbish at it.

But hey, you carry on getting riled by my inter-disciplinary physics banter!


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## Nightmaker81 (Aug 17, 2013)

Dude I'm saying you're not a theoretical physicist, like I'm not a astronaut. You're a student taking classes, like I am. You're claiming something you're not. Maybe someday you will be a theoretical physicist, but you're not right now. 

The reason I asked a perturbation theory question, is because that's the most basic of basics of theory. I'm really just trying to put this in perspective, because most theory is done on the quantum scale, and most realistic quantum systems are perturbed. I'm just being realistic as I can, and in the end if you can't do the problem I showed, you can't even do the basics of theory, because it's a long way to go.


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## Nightmaker81 (Aug 17, 2013)

Anyway this is the solution to the problem I asked. 

_The wave functions are psi(n1)*psi(n2). The wavefunction of the psi(ni) is sqrt(2/l)*sin(npix/L) , because the boundary conditions of a square well allow a sinusoidal bound state.

The eigenstates are |n1n2> in position representation

The eigenvalues are psi(ni)|n1n2>= (n1+n2)^2*sigma, where sigma represents a bunch of constants.
For part B, since it’s a wave function, position is continuous so you can’t just add matrix elements together. Finding perturbation changes is the expectation value of the perturbed Hamiltonian, so it’s |n1n2>(H0)<n1’n2’| which gives us a double integral. However the delta function makes things extremely easy since it localizes to 0. So in the end our result is

G*psi(n1)’*psi(n1)*psi(n2)’*psi(n2), the primes representing the complex conjugate. And due to parity and the way the sin function works the first order shifts are 0 if any n is even, it’s 4g/L^2 if it’s all odd.

However there’s more. Some of the cases where it’s all odd are degenerate, this means that different eigenstates allow the same eigenvalue, so the energy shift is different. Which happens with the |1,3> and |3,1> eigenstates. We have to diagonalize the matrix elements since the diagonal elements of a diagonalized matrix are the eigenvalues. The submatrix is just as simple 2 x 2 matrix all with 1s. So you find out the first order energy shift is 0 for when |1,3> and |3,1> are an antisymetrical state and 8g/L^2 when it’s a symmetrical state. 

_Like I said to put things in perspective, this is the most basic of basic of pertubation theory. You can't do any theory unless you can do something like this. I took all the highest theory level classes when I went to university, and I could keep up and get as good as grades as the future theorists of my class, but I did it through pure work ethic. The theorists I interact with have intelligence that are unbelievable, and an intuitiveness and understanding that is way beyond me. To really be a theorist, you have to be on another level.


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## Mick Travis (Aug 18, 2016)

Nightmaker81 said:


> I did it through pure work ethic.


It still looks like fun.



Nightmaker81 said:


> The theorists I interact with have intelligence that are unbelievable, and an intuitiveness and understanding that is way beyond me.


At least you have the tools to wake up with the answer to life, the universe and everything.


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## HAL (May 10, 2014)

> Dude I'm saying you're not a theoretical physicist, like I'm not a astronaut. You're a student taking classes, like I am. You're claiming something you're not. Maybe someday you will be a theoretical physicist, but you're not right now.


And dude I'm saying I'm a student taking a specific route guided towards the field of theoretical physics. I don't do _any_ labs or astrophysics for exactly this reason. 100% of my time is spent doing purely mathematical work. So when I'm done, I'll be a certified theoretical physicist.

Just like if you went through astronaut training without actually going into space, you'd still be a qualified astronaut, ready and capable of going at any moment.



> The reason I asked a perturbation theory question, is because that's the most basic of basics of theory


No, it's the most basic of basics of theory in _quantum physics_.

It seems that you're mainly on a quest to show that you know a certain amount of advanced quantum mechanics, to try and prove something to do with all physics being the same, and to prove that my specific 'theoretical physics' route is pretty much the same as your standard physics route.

You're wrong, and I already told you why. I'm covering tons of material that is specific to _theory_ that other physics routes typically do not take. A lot of it is taught directly by the maths department of my university. This is because theoretical physics is basically applied maths.

I give you this link again - THEORETICAL PHYSICS - note how I could go right up to Masters level, including my own research project (potentially published, but I humbly doubt it), while still having not done a jot of the super-advanced quantum mechanics you seem to be obsessed with. For example if I take the advanced fluid dynamics route, which is what I'm currently leaning towards. It's still entirely based on theory.

This is because most theory is not done on the quantum scale. I think this is the huge misconception you're making - you think it's all super-snazzy conceptual string theory sort of stuff. It isn't. I just told you I'm learning a ton of fluid dynamics right up to the geophysical scale using an extremely rigorous and entirely theoretical mathematical basis, using tensor calculus, multi-variable PDEs, and loads of other horrible mathematical methods for modelling fluid-based systems. It isn't open to any other branch of physics in my university. In fact it isn't open to anyone other than us theory students and pure maths students who want to do some applied maths. A point worth noting, also, is that the maths here is not necessarily a whole order of extra difficulty, it's simply that I'm doing _only_ theory-based topics, while other students delve into doing lab projects and stuff.

I literally have zero idea about perturbation theory at this time. Not a jot. Never heard of it. Wait a couple of weeks and I'll be there.

But that's not important. You're picking one super-specific area of the most widely popularised topic in physics, in an attempt to prove that you know just as much as any student regardless of the degree specification they take.

So I'm going to repeat this: _Theoretical physics is not just quantum mechanics_.

Try telling me about coset decoding and the use of dual codes in the theory of sending information.
Try telling me about how to mathematically model a slider bearing using lubrication theory.
Try explaining to me the physical meaning of the Reynold's number and how it relates to the Navier-Stokes equation.

This is all theory-based study, using complex mathematics to model the physical world, not just at the quantum level, and is beyond the scope of most standard physics degrees. Maybe you've done all that and if so, well done. But I'm only in the first semester of 3rd year. I already said and pointed out how the stuff I'm learning now simply becomes more specialised in later stages, to the extent that by the end of it all, what I know will be vastly different from what you know, and that's before any level of research or whatever comes into play. This is because we have taken different routes in physics.

Also I doubt theoretical physics is beyond you. It's honestly just more of the mathematical stuff every physics student learns. The only reason it gains its own specialist category is because it isn't just 'more' mathematics, it's _only_ mathematics. That's the difference. By the end of this, I'll be able to mathematically describe more aspects of the physical world than you, while you will be able to perform professional experiments that would probably go up in flames if I attempted them because I have no idea about experimental physics - literally _no idea_! Something to do with sigma error or something... really I don't know, ha.

Anyway I think this is going way too far now. The images I posted were pure banter. I thought these kind of jokes were fairly normal among STEM specialisations. In response, you seem to be on a desperate mission to point out how the knowledge of theoretical physics students is exactly the same as that of standard physics students. This is wrong. Otherwise why the hell would any university offer separate degree titles for each specialism?


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## Nightmaker81 (Aug 17, 2013)

How would you find the integral of cos(x)^3/(5+4cos(x)) from limits of 0 to 2pi using the residue theorem. What summation do you use, what kind of expansion do you use, and what singularities do you get

You have a differential equation of this form: 









What's the solution. 

These are really easy math problems that any theorist should know and they're purely mathematical


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## Nightmaker81 (Aug 17, 2013)

_

_
_Try telling me about how to mathematically model a slider bearing using lubrication theory.

_This is viscious flow and lubrication theory is a differential equation showing the motion of an object when one dimension is much smaller than the other. Assuming the slider bearing is a finite plane with velocity in the z direction, you can use kinematics to make an equation relating velocity. 

You can then integrate between the two plane heights to find a solution for momentum. Then you can use consevation of mass and continuity to setup more relations. It's useful because conservation of mass in continuity is just the partial derivative of density*velocity in a direction in each direction. Since pressure is constant across the film(I'm assuming it is for the thinness of a slider), you can also relate an equation of velocity in all directions with a partial derivative in respect to pressure and the spatial coordinates. You couldn't do this if pressure was a changing quantity because otherwise you'd get a dP term you have to worry about and it's a much harder thing to solve, but since it's constant you have a nice velocity to spacial coordinate relation
_
Try explaining to me the physical meaning of the Reynold's number and how it relates to the Navier-Stokes equation.

_Reynolds number is the quantity used to describe the ration of laminar forces to viscous forces. Navier stokes is an equation used to describe the viscosity of flow. The reynolds number is important because you can use it to find the ratio of laminar to viscious flow. 

Reynold’s number has a direct effect on transition and where it occurs. Using the assumption of in compressible flow, and in some cases compressible flow we see that the higher the Reynold’s number causes transition to a turbulent boundary layer to happen at a quicker rate. Assuming all other things are constant, you’ll need much more of the chord on any body going through a flowing medium to get to a higher Reynold’s number. This will indirectly effect the pressure distribution and the to thickness to chord ratio of your object 

The point is I covered all these things too in my classes. They're just classes, and whatever title your physics degree has is just the type of classes you take and it's just a formalism. Which is my whole point. You're not an actual theorist. That's not an insult, because very few people are. 

You're a theorist in training, but you're not doing full blown theory, you're taking classes. It's not to correct for you to claim you're a theorist, because that takes a lot of years of hard work and dedication. I know you're making jokes, but dude you're not doing theoretical research, you're just taking classes


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## Stelmaria (Sep 30, 2011)

Nightmaker81, good luck with your research. Let us know when you've published your paper!


@HAL, if you want to talk about yourself, then make your own damn thread!


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