What are /r/Physics' favorite Products & Services?

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I'm actually curious whether anyone knows of another example that is worse without dipping into alt-med/new age/free energy/tabloid sites. (This one popped up in my Google newsstand feed.)

Edit: a few have said that they do not want to give pageviews/ad money to an article so atrocious. Here is an archived version from the Wayback Machine.

Not about Feynman, who I love and have read many books on, but I found this biography of Oppenheimer absolute fascinating:

https://www.amazon.com/American-Prometheus-Triumph-Tragedy-Oppenheimer/dp/0375726268

I had no real interest in the bomb or the war when I picked it off the shelf. I also had no clue who Oppenheimer was. I was looking for something different. And it paid off. Both Oppenheimer and Feynman were fascinating people who lived in fascinating times. We are at where we are because of both of them.

I don't know, but I imagine civil and mechanical engineering firms are the chief offenders. According to a recent publication from the American Society of Civil Engineers (ASCE), "The U.S. customary system of units continues to be the prominent system used in the United States". Also, if it wasn't still in moderate-high demand, we wouldn't be seeing modern undergraduate textbooks published with a substantial makeup of problems in U.S. customary units.

I do not believe this is correct - The instability created by a quantum fluctuation may or may not be strong enough to propogate to the bulk of the fluid. Specifically see this article for a brief discussion on the threshold for vortex formation.

Also the formation of these types of instabilities are generated by shear gradients, which are on some kind of order of length scale associated with the viscosity and local velocity of the fluid. I am not certain you could convince a physicist quantum fluctuations are the cause of the instabilities due to the threshold (flow rate) dependence of the instability.

Hurry only 2 left in stock.

I highly recommend TeXmaker, a free crossplattform lightweight tex editor with syntax highlighting and a preview window. When installing, make sure you have miktex installed before, and all the settings should be fine as they are and you should be able to just use it without much fiddling around=)

I don’t know about the specific structure of these feathers but this looks like an example of structural coloration. Someone with expertise in biological structures might be able to provide more info but the gist is that there are different mechanisms for causing this phenomenon including things like microstructures in the feathers that cause the interference of visible light, allowing for different colors at varying angles, etc..

Neat find!

I think it might be almost as much of an exaggeration to say "General Relativity can be quantised" as /u/Noodled9 says. We can, as you say, use techniques of effective field theory to modify a Lagrangian to make predictions about the effects of gravity when curvature is low.

http://www.scholarpedia.org/article/Quantum_gravity_as_a_low_energy_effective_field_theory

There is still a large degree to which GR is very hard to deal with, just like QCD is a lot harder to deal with than QED.

From a laboratory experimentalist's point of view, of course, gravity's quantum effects are a complete non-issue, because the effective field theory tells us they are unmeasurably small, or, if you do things like experiment with neutron beams, you can calculate everything you need semi-classically.

But from a cosmologist's point of view, or a theorist, there is an enormous amount left to understand. If you have to explain in a phrase what these people are challenged by, "the difficulties of fully treating GR as a quantum theory" seems to me like a good summary.

Professor Orlando Ferguson has already debunked this presentation. A major cornerstone of the Flat Earth Society. I mean common guys, I thought this was common knowledge.

This one should help with your first question.

And this one should help with the second.

First, you are awesome.

The hardest thing is going to be the math. You must know it cold. Any gaps will slow you down until you just can't keep up any more. Try http://www.khanacademy.org/ to see if that format works for you. Otherwise, may be try and find out your school's textbook and work through it before taking the class.

For fun, try tutoring underprivileged high school kids in math and science. It's incredibly rewarding, and teaching is the best way to learn a subject inside out.

You might want to read "So Good They Can't Ignore You" by Cal Newport. It gives a pretty strong argument for why following your passion is a bad idea. He argues that passion is something you cultivate, not follow.

If you've no time for a book, then just read this blog post:

http://calnewport.com/blog/2010/01/23/beyond-passion-the-science-of-loving-what-you-do/

I'm pretty sure that this is an error on the author's part, nanofortnight from HN says > Not requiring energy is a mistake from Wired. A superconducting version of the drive would be able to provide much higher Q, and thus much higher static thrust to power ratio. It would also have much better performance at higher waveguide velocities. http://www.emdrive.com/theorypaper9-4.pdf#page=9

Here's what must be a good one. The author is an excellent historian of science. I just enjoyed reading his story of Lorenz's theory of light scattering, available through Researchgate.

I'm waiting for a cheap(er) copy to turn up on abebooks.

Dirac bio by Helge Kragh

LaTeX is awesome I second this. Once you get used to the syntax, it's extremely easy to get documents to "look" how you envision them.

It's also very well supported and make sure to check out all the packages that go with it.

• I recommend the Wikibooks LaTeX Guide for a run through and tutorials on how to do stuff.

• I also recommend TeXworks as my favorite LaTeX editor. It's much more simple than a lot of dedicated LaTeX editors in that it doesn't have all the buttons and automated bells and whistles other editors have, but it automatically downloads any package you declare in your document so you don't have to go searching for them.

Most LaTeX guides list useful basic packages and what they do, but I've found some real gems more-so on happenstance and on accident.

I've been there. Here is a photo I've made. However, this is not the actual proton source, it's only a model. The actual proton source is in the big box behind the model, which is the start of LINAC 2, the first accelerator of the LHC accelerator chain.

This is some kind of weird gatekeeping where AI keeps being redefined until it just means adult human intelligence. I have a textbook that literally has artificial intelligence in the title.

Ahh! I was once you!

Okay, here's the thing, math math math! Math at least two hours a day when you're not in school, I'm not kidding, and I don't wish I were. I have this buddy, Khan, who'll teach you the main concepts of calculus, linear algebra and differentials. You can even practice some calculus problems, iffin you need!

Does your high school have a Science Olympiad team or sommat of the like? I'd hit that up! Honestly, it's worth it. Really good times and you learn so much.

Oh, and you can read and stuff, as well. You can read The Elegant Universe, The Trouble with Physics, look at QED by Feynman, etc.

So, math and physics! Keep practicing! Don't neglect other cool subjects such as chemistry and biology and philosophy and stuff, however. These are all important, too, I think! One thing I hate more than anything else is a peer who scoffs at the idea of like microbiology or something.

Oh, and learn to program. You'll have to learn it eventually if you're going into astrophysics, and you better start learning how to properly code now. I hate looking through some of the crap grad students often spew out. :| Here is something that can help you get started with that.

Oh, and as an undergrad, go to a grad student or a faculty member, ask what kind of research they're doing and get all involved and stuff. Getting into grad school isn't just about grades and things, it's also about who you know and what sort image you've established for yourself.

Or something.

It's a bad spelling of a pseudonym a character picks for himself when trying to sneak in clandestinely into a city, in "Avatar: The Last Airbender". EDIT: here, at 2:45.

Your biggest problem seems to be the point where they point out that the device relies on imaginary physics. I thought that was a nice moment.

Here is the Google ngram for "quantum vacuum virtual plasma."

https://books.google.com/ngrams/graph?content=%22quantum+vacuum+virtual+plasma%22&case_insensitive=on&year_start=1800&year_end=2013&corpus=15&smoothing=3&share=&direct_url=

It's weird that particular combination of four words has never been published in the English language, at least to the extent that Google has gotten around to scanning books. What about Google scholar? Oh! One result. Aha, it is an established concept!

http://scholar.google.com/scholar?hl=en&q=%22quantum+vacuum+virtual+plasma%22&btnG=&as_sdt=1%2C5&as_sdtp=

Oh.

Very well established and important in our understandings of many phenomena, which is to say that it appeared for the first time in the English language just in time for that study.

A good way to see how a scientist is viewed in their field is to see how many papers they have published, and how popular those papers were (aka how many people cited that paper in their own). Google scholar lets us quickly search and find this out.

Michio Kaku has 2,130 search results and the number of citations on the first page of results is ~2200. Not bad..

Now compare that to Stephen Hawking who has 21000 results and the number of citations on the first page is ~25000.

He's well cited, but he is not as popular in the academic world as he is in the TV world.

Here it is on the Cambridge site and here on Amazon

The copyright date is 2017 so maybe they are still rolling it out. But it looks like it is still the 2nd edition with the same content as the 2004 Pearson one.

£42 is almost a reasonable price for a hardcover textbook. Good for Griffiths/CUP; screw Pearson.

This is an impact driver. Of course pneumatic and electrical versions are common now, but in this case the manual version is what you need. When you hit it with a hammer, the force holding the bit in to the screw rises as the torque on it increases, making it unlikely to slip. Having said which, if you hit it too hard you'd probably break the carb anyway.

Most of the answers here are bullshit. Try section 3 of my Masters report. If that is too much for you, here's a high-level overview:

• assume excitations of fundamental fields are open/closed strings, which trace out worldsheets (not particles which trace out worldlines)
• assume the action of the system is proportional to the area of the worldsheet (since the action of particle-like excitations are proportional to the length of the worldline)
• fields are functions of two spacetime co-ordinates (since a worldsheet has two independent directions on it)
• assume this action has supersymmetry, not just Poincaré symmetry

As a result of this, you can show that different excitations of the strings can give rise to what look like different particles at low energies. At this stage, you have various legitimate choices you can make - the number/kind of supersymmetry generators, and the boundary conditions of the strings.

This gives rise to 5 legitimate theories, all requiring 10 spacetime dimensions. Witten showed that all 5 of these are actually different limits of 1 underlying theory requiring 11 spacetime dimensions, i.e. M-theory.

Of course, we only observe 4 large spacetime dimensions, so if the above is to be true, 7 of those dimensions must be compactified in some way. There is also some hope that in the low-energy limit, M-theory yields 11-dimensional supergravity, which is what we could hope to observe in the today;s world. The different things we could observe depend on how those 7 dimensions get compactified, and there are many ways this can be done (a figure that's thrown around is 10^500 ).

There is no experimental support for any of the above assumptions. The assumption of supersymmetry being an existing broken symmetry of nature has support independent of the rest of the framework of M-theory (or strings in general).

Have you had a look at the [khan academy](www.khanacademy.org)? I get my students to go there if they are missing some basic math skills that they need for my Physics class and they generally find it pretty helpful. For instance I just searched there for 'Gauss elimination' and found this video which gives a pretty good example for using Gauss-Jordan elimination to find the inverse of a 3x3 matrix.

You just need to practice your math until you become fluent at it. You should be able to look at a problem and, once you figure out what math you need to solve it, the actual calculations are elementary, like second nature. It's just like learning any other language, or a new sport; you're going to suck at it and struggle at first, but by doing lots and lots of practice of the basics, and then building up to the more difficult elements you will have success.

Don't let yourself worry about what others in your class think of you or your maths ability; you're in college now not high school, no one gives a fuck about what you're doing after the first few weeks.

Thanks for the mention. I created Universe Sandbox.

We've been working on the sequel for almost 4 years and are nearing release on Steam this Summer. If you like the first one, you might really enjoy Universe Sandbox ².

The creator of xkcd wrote a book on 'Serious scientific answers to Absurd hypothetical questions', I really enjoyed it, it was quite entertaining:

Sample of what some of the stuff in the book looks like:

https://what-if.xkcd.com/137/

Book on amazon:

http://www.amazon.com/What-If-Scientific-Hypothetical-Questions/dp/0544272994/ref=tmm_hrd_swatch_0?_encoding=UTF8&qid=&sr=

>I do like books that spend some time with the history of physics though.

Have you read Weinberg's To Explain the World?.

Keep in mind that "what philosophers think" and "what philosophers have to teach in an introductory class in order to not overwhelm students" are different things. If you found yourself in an introductory algebra-based classical physics class you might similarly be a bit frustrated.

In general, pure physicists are pretty ignorant of philosophy of physics, and pure philosophers are ignorant of philosophy of physics. Philosophers of physics are the best resource. Here is a good book on metaphysics from a physicsy perspective that gives a good overview, both chastising philosophers for not doing good physics, while also explaining all sorts of things relating to the philosophical implications of quantum mechanics and general relativity that the majority of physicists are pretty ignorant about.

Feynman admitted several times that the mathematics was not his strength. His strength was lateral thinking; one of his gifts was to be able to ask the right questions — even stupid ones. The story he tells in the chapter <em>A Different Box of Tools</em> in Surely You're Joking, Mr. Feynman illustrates this point.

Start out with khan academy http://www.khanacademy.org/, I honestly havent watched the physics videos as Im currently using the site just to learn linear algebra but judging on how well he simplifys concepts in maths, I assume to does an equal job for physics. Learning physics early on is also fairly non linear so you can take a subject in it your interested in and start with that.

http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html is also a nice reference

Bookwise something short enough, fairly comprehensive and fairly easy is six easy pieces, its a compilation of some of the feynman lectures on physics and is a very good introduction to alot of the main concepts of physics, although slightly outdated towards the end

It's already protected by copyright: that happens automatically. You can't sue for infringement until the copyright is registered, but there is no urgency about that. However, copyright protects only the creative expression, not the ideas. Copyright just means that no one can make copies of it without permission. It's useless unless you think someone is going to pay you for the right to publish the work. Put a Creative Commons "public domain" license on it so that people won't be afraid to distribute it.

If you want a professional physicist to review it you wil probably have to pay. Try this.

Very few particle theory PhDs get faculty job offers. Fewer than in other fields of physics.

For example, here is a list (possibly incomplete) of new faculty hires in 2011. You can check earlier years too. They average ~8 faculty hires per year, although this number may be a bit low because some of the accepts or offers may not have been reported, and it may not count faculty jobs at no-name places outside the US and Europe. (But do those really count anyway?)

Meanwhile, the postdoc rumor mill shows that, this past year, there were at least 190 people accepting postdocs (yeah, I counted). Now, this list is made up of people getting their first postdoc, as well as people getting their second or third postdocs (or more). Still, it should tell you that the majority of people who make it to the multiple postdoc stage don't get a faculty job offer.

It breaks my heart to dissuade people from theoretical physics. But it's labor economics: yeah you want to do it because it's awesome, but everyone else wants to do it too for the same reason, so there's huge demand for a limited number of spots. I say, if you still love physics, try going for experimental particle or (even better, since you also have lots of industry job prospects) experimental condensed matter. I wish I had done that.

My favorite language? Probably C++ / CUDA. I use it all the time for research and it's growing on me.

The language I want to like the most? Julia. It's an up-and-coming JIT compiled language that has the simplicity of python, but boasts of speeds closer to C++ (if you write well optimized code). I would definitely suggest taking a look at it, if you are interested!

I actually did my BA thesis in 2013-14 with these guys (the people working at this company are genuinely amongst the very smartest people I have ever met). My project was a review of the mechanisms of potential radiation damage, as well as investigating possible methods of shielding the main current coil ('Effects of Radiation on Materials in Spherical Tokamaks' if you are interested in giving it a read!).

In Deuterium powered spherical tokamaks, the vast majority of energy that is 'lost' is carried away by 'high energy' neutrons. They are high energy in that they carry 4 MeV, but they aren't really relativistic despite their name. These neutrons are a significant issue, both because they penetrate the outer walls of the ST, as well as heating and damaging the central current-carrying coil. Thus, one manner of keeping the plasma going would be to reflect the neutrons leaving the plasma back in, thereby sustaining the reaction. Another concept is to use the machines as the ignition key for sub-critical fission reactors (search Google for these, they are all over it), or to dispose of hazardous (medium half-life) nuclear waste, without the need for the ST itself to be energy producing.

The guys working at this company and at other institutions in America and Japan are working under the idea that a smaller chamber lends itself to more energy efficient machines. The reason for this is twofold. Firstly, in larger machines, such as the traditional tokamak or the future machine ITER, there is a real issue of keeping the plasma from corking-screwing upwards (or downwards) into the top (or bottom) of the device. Secondly, smaller devices like STs have been shown to be more 'efficient'. Technically speaking, they have better 'beta values', which is one of the quantities one wants to maximize, in order to get the most energy out of your device.

Let's say our streetlight is a 100 watt LED that puts out pure green light at 550 nm.

(100 Joules/sec) / (1.602e-19 J/eV * 1240/550 eV/photon) = 2.8 x 10^20 photons per second

These photons spread out isotropically, so the intensity decreases as 1/(4 pi r^2 ). For a galaxy diameter of 9.5 x 10^20 meters, this gives us a photon flux of

2.4 x 10-23 photons / m^2 s - This is about 60 photons hitting a planet the size of earth on the other side of the galaxy in the entire time between us and the romans

This is great, and an advance in the field, but not nearly as original as portrayed.

It is a field that has been developing over the last 80 years or so. See Into the Cool: Energy Flow, Thermodynamics, and Life for a great summary.

Hell, I've just gone public with a social networking project called Babbling Brook that I have been developing for the last three years. It extrapolates the theory a step further by looking at social structure as resulting from the same process.

Landau and Lifshitz's Course in Theoretical Physics Vol. 1-3 and 6-8 are online. Classical field theory, quantum mechanics, electrodynamics, and fluid mechanics.

They're dated but terrific texts, very concise and to the point. A mathematics background is recommended.

https://archive.org/search.php?query=creator%3A%22L.D.+Landau+%26+E.M.+Lifshitz%22

Yes, see An assessment of habitat pressure, oxygen fraction, and EVA suit design for space operations Acta Austronautica 32:1, 39-49 (1994) They went down to 345hPa 70% O2, don't see why you couldn't go down the last bit to 0.2 bar as well.

edit: corrected 345 hPa, thanks mrmoen!

Universe Sandbox ² is a complete rewrite of the original 3 years in the making. We've got a full time physics developer on the team, who is much more talented than I (who wrote the original version).

"moment" in "moment of inertia" refers to a much more general mathematical / statistical concept (see https://en.wikipedia.org/wiki/Moment_%28mathematics%29). In some sense, the moment of inertia can be thought of as a measure of the variance of a mass distribution.

Also, apparently Euler was the first person to use the label "moment of inertia" (see Mach's "The Science of Mechanics" (1919) p.173-187, https://archive.org/details/scienceofmechani005860mbp), but I don't know if he was the first person to use the term "moment".

Try Khan Academy videos for help with specific topics: http://www.khanacademy.org/science/physics/mechanics

I also recommend speaking to your teacher/TA about it because they can offer personal tutoring or recommend tutors that can be a great help. Write down any specific questions/concepts you have trouble with and bring it to them, don't expect to be able to remember it all.

It's a lot to ask to be able to tackle each subject on your own and there's no shame in asking for help. I have received help from my professor for Elec/Magnetism help nearly every week and I go to the weekly tutoring sessions because I have questions or a little confusion each week. Put away any pride you have about asking for help because I promise it will help in the long run.

P.S. Ignore the fact that others get it before you. Can't compare yourself to others like that or you'll be unhappy forever. Be proud of your accomplishments and desire to pursue Physics. It's a tough subject. If it's easy at other schools, then I guarantee they're not being challenged nearly enough.

Chonnes is actually right... 'Anyone of you' is not correct. It's not just a matter of semantics. However, you're right that grammar disputes are silly, and it's hardly a big deal either way.

Edit: See http://www.thefreedictionary.com/anyone

The Giancoli book is atrocious. I found this one to be much better. It's calculus based, but it doesn't go overboard with calc.

Apparently you do not understand that the astronauts in the ISS are subject to about the same gravitional force as on the ground. The reason they are weightless is that the ISS is actually 'falling' towards the Earth, in free fall.

So, if it is falling towards the Earth, why doesn't it hit the Earth?: Good question. Because it has sufficient horizontal velocity, relative to ground, to insure that it always falls towards (and above) the ground horizon. This keeps it in permanent orbit around the Earth.

Here, design your own satellites and try to keep them in orbit.

http://www.stefanom.org/spc/

Try phun.

It's a physics sandbox that is really fun. It will get him started developing an intuition for mechanics long before he's developmentally able to learn them in an academic sense.

Here's some general techniques that can provide insights:

1. Run time backwards. Instead of the ball being fired horizontally and then asking when it lands on earth, imagine the ball being fired at some angle (what angle?) from earth, and then asking how long until it reaches the apex of its parabola.

2. Change reference frame. Instead of the ball flying through air, imagine the ball rolling across an elevator floor, while the elevator accelerates upwards at g. How far does the ball get before it reaches the top floor?

Here's a fun problem that can be easily solved using these techniques: you are standing at the edge of an elevator shaft, about to jump down onto the elevator below. Right before you jump, you can push a button that will make the elevator go up at a constant rate, or a button that makes it go down at a constant rate. Which button should you push (if any) to minimize the impact of your fall?

Edit: I wrote up two approaches here for those who are interested.

This is a nice writeup, but I feel it gives too strong an impression that Einstein's General Relativity completely incorporates "Mach's principle" with the solutions of Brill, Cohen and onwards with frame dragging.

To be clear, frame dragging is clearly a 'Machian' effect, but the magnitude is generally very small as a rotating body only drags the frames 'a little'. The only truly Machian version is for the 'extremal' case in which the frame dragging is complete.

In essence: The fact that GR admits solutions like Brill-Cohen which are asymtotically Minkowski is in contradiction with a full interpretation of Mach's principle. There is a lot of subtlety in defining what is meant by all of this, though, even among those practitioners who strive to further embody something called 'Mach's Principle', see: https://www.amazon.com/Machs-Principle-Newtons-Quantum-Einstein/dp/0817638237

They have several editions on Amazon, paperback and hard cover. Barnes and Noble sells this book on its own shelf with others in the series. I am unfamiliar with any other sources. https://www.amazon.com/30-Second-Physics-fundamental-concepts-explained/dp/1782405143

Khan Academy is possibly the greatest supplemental instruction website ever created, and its physics section is fantastic. The videos are really down to earth, and explain concepts beautifully and provide great examples. This website has single-handedly raised my GPA, haha.

Good luck btw!

• put in headphones.
• go here: https://www.mixcloud.com/nevelleven/
• dam, lol. Where's my red pen? Or pink if you're feeling pretty!
• got a solution key? No? Make one.
• assign a point value to each problem.
• decide what you consider to be "partial credit" type answers and be consistent.
• grade the papers, son.

• A Brief History of Time

• The Universe in a Nutshell

• On The Shoulders of Giants

• The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory

• The Fabric of the Cosmos: Space, Time, and the Texture of Reality

• Icarus at the Edge of Time

• The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos

• Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe

• Higgs Discovery: The Power of Empty Space

• Knocking on Heaven’s Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World

• Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions

• Surely You're Joking, Mr. Feynman!

• What Do You Care What Other People Think?: Further Adventures of a Curious Character

• The Cosmic Landscape

• The Black Hole War

• The Theoretical Minimum book series

I've said it before and I'll say it again: Anything by Richard Feynman. QED is an excellent introduction to to quantum, and does not require any advanced mathematics/prior physics knowledge to understand.

Also, "Surely You're Joking, Mr. Feynman", while not entirely about physics, is a must read for all aspiring physicists.

The dev says the app:
> uses the 2D Finite Difference Time Domain method to solve Maxwell's equation on a Cartesian grid

Here's the app: https://play.google.com/store/apps/details?id=com.jasmcole.wifisolver&amp;hl=en
Sorry if links aren't allowed. If not, I'll remove the link.

Here I did some rough calculations:

IR: http://www.wolframalpha.com/input/?i=integrate+1.19268x10^-16%2F%28%28e^%282.60807x10^-6%2Fv%29-1%29+v^5%29%2F10^13+from+v%3D750*10^-9+to+v%3D+.1

Visible: http://www.wolframalpha.com/input/?i=integrate+1.19268x10^-16%2F%28%28e^%282.60807x10^-6%2Fv%29-1%29+v^5%29%2F10^13+from+v%3D380*10^-9+to+v%3D+750+*10^-9

I assumed the visible spectrum contained 380 to 750 nm and the sun is a blackbody at 5250 C at 5250 C. Also, I used 10^8 nm as the upper bound on IR. Those numbers are for comparison only, I adjusted the values to match the image on Wikipedia. The visible light integral is about 85% of the IR one.

Since the light that reaches the surface is attenuated in an uneven fashion, it is hard to tell which contains more energy at sea level. My guess is that IR contains slightly more energy at sea level.

http://www.khanacademy.org is a great place to start. Really easy to understand video's from a guy that has a real talent for teaching. Goes from the basics upwards cementing the basic knowledge that I know I wish I had when studying Calculus at High School.

Khan Academy has some great intro videos that are easy to follow and informative. They also have a ton of other stuff with pure mathematics that is both interesting and somewhat essential to understand some of the physics (I'm speaking of calculus, if you haven't taken it yet). Either way, it's a great tool and they are fun to watch

First off, start with math. LOTS of math.

This is a good version of what you're looking for that includes links to recommended methods of learning from a few physicists:

https://futurism.com/want-physicist-heres-guide/

And this is a massive compilation of free classes from various schools and such (physics is hidden at the bottom because the world is ashamed of us or something):
http://www.openculture.com/freeonlinecourses

edit for personal comment: I recommend actual books and sites without learning tutorials as the best understanding of the material comes when you have to think your own way through each problem.

any thing with or by carl sagan, or neil degasse tyson is awesomely inspirational. not exactly helpful though, carl sagans cosmos on hulu for instance, or The Symphony of Science.

Tungsten has the highest melting points of any metal. Because a light bulb involves heat to function and all things that increase heat of something accelerate their failure, this choice extends the lifetime.

The resistance doesn't change stretching of the "coils". It's already the same cross-section, and thus resistance, coiled or uncoiled. It's coiled simply to make a given resistance physically small so it can fit conveniently in the bulb.

I haven't used it myself, but I've heard that the video lectures on introductory physics from Khaaaaaaaaaaan Academy are good. And I believe they come with online example problems that aren't always the same (I think the numbers are randomized or something). It's something to think about, anyway. And if you really have trouble, go talk to your professor and/or look into getting a tutor, my college had free tutoring services for intro classes at least.

Sorta like the reddit markup, but that's just part of it. LaTeX is a full typesetting suite, so you also have control over how the document's layout renders. This snippet gives an example of the general code structure, and while it looks like it can really only do academic papers, that's not the case at all.

As for the Notepad note, yeah that's totally possible, although I imagine most people would use a text editor that has syntax highlighting like Notepad++, Sublime, or Vim.

There are a lot of simplified models which can reproduce the voltage curve of an excited cardiac cell. These usually amount to some mathematical representation of the underlying transmembrane currents which result in an action potential, and consequently leads to the observed "bumps" in the ECG.

Depending on what you need this for, you can choose which model would fit your needs the best. Some of the models have few variables (such as Fenton-Karma 3v) because they group various currents together for a more coarse-grained approach, whereas some have upwards of 60 to account for all of the complex interactions present.

Many of these models, and some background, is given here: http://www.scholarpedia.org/article/Models_of_cardiac_cell

There is no profit motif behind this project. It is funded by research grands at the moment. The primary purpose is to create awareness of the technology and to educate.

In this content I would also like to recommend the Coursera course "Organic Solar Cells - Theory and Practice" https://www.coursera.org/course/opv, where everybody with an interest can learn a lot more about the technology behind.

Quoting Jay Wacker, who left his job as a physics professor at Stanford:

> High Energy Physics has been an incredible ride for me. Yet, after the discovery of the Higgs boson, the time scale for major experimental results is growing to be fractions of a lifetime. The next major collider after the LHC will begin in 2040 — at the earliest. This is a long time to wait for a theoretical physicist who needs experimental results to validate theories.

Source: https://www.quora.com/How-did-Jay-Wacker-get-recruited-to-Quora

Now, in some sense, "high energy physics" is "true" physics, in the tradition of Newton and Einstein: it's where we learn what the fundamental "laws of physics" are. Other areas of physics, in principle, take current our current understanding of the laws of physics as granted and work out the consequences. (This is of course an oversimplification of what actually happens in real life, but it's morally true.)

Of course that leaves other areas of physics, and of course there are people who are more optimistic about the potential for experimental results in high-energy physics or about the potential to progress purely mathematically.

Well, I'm a computer science researcher so I did know about the 2nd one. But the first one came from the Google.

link

Yep.

Thank you! BTW, you should consider licensing these notes under a Creative Commons License, so that it'll be easier for somebody to adapt and build on those notes (such as converting it into LaTeX).

3 names of trolls I remember from sci.physics usenet groups:

• Y Porat,
• Androcles, and
• Vertner Vergon.

Y Porat makes Vergon look like a model of sanity.

Hello :) I have (had) a great experience with “Papers”: https://www.papersapp.com. I used it continuously in medical school, medical research and during my brief stunt in quantum physics. It’s a very flexible software, available on most platforms. Give it a spin, you won’t be disappointed!

Perhaps this will assist you in understanding.

http://www.scholarpedia.org/article/Bell's_theorem

Insights in physics (can) simply sit by themselves. As my undergrad professor rightly said; "Nature does not lie" Our interpretations might mislead us into making the wrong conclusion, but that doesn't change the underlying mechanism. We have discovered that nature seems to be fundamentally probabilistic, which defies our conventional conceptions of reality in most contexts. This property of the universe (whatever its interpretation) is quite standalone.

This is not to say that there aren't philosophical implications to these discoveries, just that those discussions don't necessarily tell us anything about the world. Since we are talking about Bell's Theorem, we are talking about particles in entangled states, this is a very special type of system, and one whose creation I am by no means an expert on (my experience with it and Bell's theorem consists of 2 lectures in grad quantum). It may be worthwhile to point out that in entangled contexts, Bell's equality is violated.

Regarding uncertainty at "normal scale", the uncertainty is just too small to be measured with anything that can be held in your hand. You can't pick up a ruler and measure something in two different places, these effects are immeasurably tiny at human scales. Even on molecular scales you can treat atomic nuclei as classical point particles with little difficulty (although that is emphatically NOT true for electrons). This inherent quantum uncertainty doesn't cancel at all, we are quite literally so big that we can't see it.

I would try exercising, eating well and getting more sleep. And above all reducing your stress in any way you can. Find out what works for you to reduce stress. It could be as simple as taking half an hour every sunday to plan out what you have to do each day of the week, or doing 30 minutes of exercise or reading or computer games each day.

As for the concepts, I recently just discovered a website called brilliant.org. It has short, fun little lessons and quizzes about all kinds of physics, chemistry, maths, logic, philosophy, and more. It's really simple, and I've re-learned all kinds of concepts that I thought I had long forgotten.

There are probably more websites like this too. It's a great way to see some achievement in a low-stress and fun way, while learning back all your old concepts.

This, along with the other tools available from the dropdown, are excellent and are great examples of apps where the processing is all done client-side. I'm also impressed with what I see at your web developer tools site

Are you familiar with r/usefulsites - if not, you may wish to consider a post over there.

While cool, I have to admit that I'm tired of seeing 2D representations of a 3D phenomena that looks entirely different in 3D. I have yet to see a compelling 3D visualization. This is the best I've found: Skip to ~8 sec.

https://www.bing.com/videos/search?q=3d+visualization+of+gravity&amp;FORM=VIRE13#view=detail&amp;mid=F120488027FC30EBD914F120488027FC30EBD914

I recommend "Mathematical Methods in the Physical Sciences" by Boas. This is the book that I used for my theoretical physics course. This course was described as "a condensed version of all the math you need for a physics degree". The book is essentially the same thing. I would just download a .pdf of the book. You can see a preview with the table of contents here:

http://www.4shared.com/office/d2qRFneq/boas-mathematical_methods_in_t.html

I would just torrent it from somewhere... Here it is for ~$60

http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&amp;field-keywords=mathematical+methods+in+the+physical+sciences

Introduction to Quantum Mechanics by Griffiths is a pretty good first read in QM, assuming you have some mathematical background (PDE's and some linear algebra).

A more serious read is Quantum Mechanics by Cohen-Tannoudji et. al.

^Sent ^from ^Reditr

Since Dr Tyson has spoken about his favorite form of death as spaghettification (sp??) while falling into a black hole. Would he care to comment on the Black Hole Firewall paradox, and Stephen Hawking's recent publications on the problem?

for info, see

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

Also

Yes, Virginia, Black Holes Exist!

I use MiKTeX and TeXnicCenter (install in that order). You just need to let TeXnicCenter know where you installed MiKTeX and you're all good. Don't worry about installing every package at first, you can always add them later.

For anything with statistical mechanics i whole heartedly recommend Mandl. Doesn't have much (I believe in fact nothing) on QFT's but it is certainly the best book I know for stats

Amazon Link

And it is also blatantly untrue that one can add velocities in a Galilean way, and yet I do non-relativistic quantum mechanics all day every day.

Your opinion screams "I have only studied economics at the introductory level!" There are many situations in which consumers and firms empirically act approximately rationally. There are also many many economists studying what happens when people don't act rationally. Two influential books are Dan Ariely's Predictably Irrational and Bryan Caplan's The Myth of the Rational Voter. In addition there is a whole literature on models involving so-called bounded rationality.

I've had the time to create an app that integrated the measured acceleration twice to obtain position. In my head it would be a fun thing to use your phone as a computer mouse.

Turns out the accelerometers of phones are cheap af and cause drift. Integrating it twice showed some significant drift/error that made the whole application unrealizable.

I expect the same would happen if someone were to integrate the measured acceleration of a car for a long time. So while easy in theory, it will be quite difficult in practice.

I came across this app some time later: https://play.google.com/store/apps/details?id=com.samruston.myapplication

On my phone it measured the same tabletop as 1m, 2m and 50cm in 3 consecutive identical measurements, but the Play Store reviews show some accuracy. I guess it's really dependent.

Anyway, fun stuff!

BR Martin's book is good, short, to the point and free!: https://archive.org/details/StatisticsForPhysicists

I liked PC Gregory's book a lot: Bayesian Logical Data Analysis for the Physical Sciences.

Sure, to a degree. However, at .9999c if you are traveling 100,000ly you would still experience 1414 years. So you'd still be dead before you got there.

For graphing equations I highly recommend the website desmos. I'm in undergrad and use it every day; the intuitive interface and ability to make parameter sliders are invaluable to understand formulas.

This may look simple, but it's really well done by Wolfram Alpha - Integrate root of tanx and click on show steps (awesome!) http://www.wolframalpha.com/input/?i=integrate+tanx^1/2

I was completely blown away by detailed steps given by Wolfram Alpha

x^i blew my mind the first time I saw it.

Edit:

>Whether is a piece of knowledge or a complex calculation that would have been painfully long to resolve.

I couldn't even wrap my head around how to plot x^i . Complex exponents were a major gap in my mathematical understanding, so seeing Wolfram so effortlessly plot this function truly blew my mind.

Khan academy will get you started. I don't know for sure if the big Universities have that many physics courses up, but it's worth a try. MIT, Harvard, Stanford, etc.

direct link to article: https://medium.com/the-physics-arxiv-blog/a-mathematical-proof-that-the-universe-could-have-formed-spontaneously-from-nothing-ed7ed0f304a3

So this article claims that quantum fluctuations in QFT can give rise to the big bang. But, to me, this really doesn't say much. Can an actual physicist give an explanation here? Isn't this old news? What new physics has been discovered here?

Okay. So I'm not that familiar with that blog. I did, however, read this article: https://medium.com/the-physics-arxiv-blog/the-astounding-link-between-the-p-np-problem-and-the-quantum-nature-of-universe-7ef5eea6fd7a

Now, I don't usually know the topic they write about so I have to judge them based on the topics i do know. And this article is filled with misleading comments, wild speculation and straight up factual errors. Factual errors are always the easiest, so let's just pick one,

> What’s interesting about NP-hard problems is that they are mathematically equivalent.

No. The halting problem is NP hard and TSP is NP hard. They are provably not mathematically equivalent.

Anyway, I can go on tearing this article to pieces. I could mention the fact that Scott Aaronson had to waste his time writing a blog post debunking the paper. Probably because of the medium.com article.

How you can call that a long history of good science reporting is beyond me. Calling it science reporting at all is too much of a compliment,

I'm a grad student in Mechanical and Aerospace Engineering, doing computational fluid dynamics. Right now I'm working on meshless methods for compressible flow solvers.

Like derioderio said, fluid dynamics is a huge field, so definitely check out the journals mentioned, and if you're interested in the numerical aspects as well, the Journal of Computational Physics is a good one to take a look at.

You'll definitely want a solid foundation in solving PDEs, complex analysis would be good too. And programming is pretty key unless you only want to do experimental work.

https://www.eeweb.com/tools/loop-inductance/

Assuming 1000 mm diameter copper with a length of 9.461e+18 mm (1 LY), inductance is 2.19e+11 H

Then there's resistance.

https://www.omnicalculator.com/physics/wire-resistance

So maybe 159 M-ohm.

That light isn't lighting up.

No, sweeping increases the surface temperature. Click here to read the paper about it. I thought the same thing. We did research before making the infographic.

In a sketchy sense: how fields couple to eachother tells us what kinds of interactions particles can have. In order for the Higgs mechanism to work, you need couplings to fermions that look like (H)(anti-f)(f), which means the standard model tells us it likes to decay to quark-antiquark pairs or to virtual quark-antiquark pairs which then annihilate to pairs of gluons. In principle, this kind of reaction can be run in reverse, so we try to do so by colliding things at high energy. The high energies are necessary because 1) we believe the higgs to be fairly hefty, so that conservation of energy and E=mc^2 demands the collisions have very high energy in the center-of-mass frame. 2) When protons collide at high energy, it's really the collisions between the quarks and gluons inside that determine how much energy you have to work with. This is usually some small fraction of the total, so that 7TeV proton collisions typically only produce events with ~.5 TeV - 1 TeV energy.

Also, the standard model doesn't predict what the Higgs mass should be. All we know is what we've ruled out so far. It's ruled out (to 95% confidence) below 114 GeV/c^2, and in a small range around 160 GeV/c^2. Doing a statistical analysis on a wide variety of observables we've measured seems to favor it being very close to that 114 limit, but it doesn't in principle have to be there. The only other bound we really have on it is that if it's heavier than something like 500 GeV/c^2 the standard model breaks (in the sense that probabilities no longer add to 1).

<em>Relativity: The Special and General Theories</em> by Albert Einstein helped me understand relativity rather well.

At the time this book was written, there werent many sources on Relativity that explained the concept in a non-mathematical way. Einstein wrote this book as an attempt to share the theory with the general public.

I'm sure some of the other books listed here are easier to understand, but I really enjoyed reading what Einstein himself had to say about the topic, and this book is pretty cheap.

Could you be more specific on what you are having a hard time with? I personally found that I can get what ever knowledge I need for free on the Internet just as long as I put for the effort, but some books have helped me tremendously (such as Calculus for Cats when I was studying Calculus). Youtube makes learning surprisingly easy, and they also have the WikiPlays channel that will read Wikipedia entries to you.

You may also want to diversify your study material, as I too have found that the supporting material of certain curriculums more formidable than educational. I would recommend finding free physics courses online, from places such as MIT Physics, or Open Culture.

Other than that, I would just recommend viewing the hard material at every angle until you are familiar with it.

I hope this helps.

Thanks for the info, you're absolutely right. I did some "research" and I found this paper which details two existing methods as well as a new method by the writer.

It's not because of Gray's Anatomy, it's because the medical field is much, much more on the "people" side of the People-Things spectrum, which is the most robust way to classify sex differences in occupational interests.

https://www.researchgate.net/publication/282433629_Gender_differences_in_STEM_undergraduates'_vocational_interests_People-thing_orientation_and_goal_affordances

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4340183/

https://brilliant.org/

It's a website where users contribute mathematics, compsci, and science problems in a number of different areas open-source and users solve them in progression.

I think it could be a great tool for enhancing your basic mathematics skills, but it doesn't look like anyone's contributed many physics problems yet.

Honestly, the most used IDE among physicists is probably something like vim, because physicists in general can't code. Real programmers use emacs :-P ... nah, just kidding.

As someone who does code a lot, I don't think it's all that useful to take IDE recommendations from other people too seriously. Try out the free versions of a bunch of different ones and see which you like. IDE preference is a very personal thing, and each person will value different attributes. What I would recommend is making sure your IDE offers code completion and debugger integration and that they work well for you, because those are two of the key features that separate IDEs from glorified text editors.

My IDE of choice is Wing, although you need to get the pro version to get the debugger integration. If you can afford the cost I think it's worth it, but if you're on a tight budget, probably not.

You should definitely check out the Jupyter (formerly IPython) notebook, even though I wouldn't quite call it an IDE, because it's well suited to the kind of coding you're likely to do in physics. Scientific coding involves a lot more "one-time-use" code - that is, you write a code snippet and run it immediately just to calculate something once or twice, rather than writing a script or program that you're going to be running over and over again - and the notebook workflow is optimized for that. "Proper" IDEs like Wing, PyCharm, Spyder, etc. are more targeted at the kind of development where you write a program that you're not going to be running until later, probably in a separate environment.