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    Quantum Springer discount code CYBERWEEK19 - English IT books only 7 Euro

    Use the discount code CYBERWEEK19 to purchase English IT eBooks from Springer online for only 7 Euro. Go to the checkout and enter the code. Afterwards, you can proceed browsing the book list and it automatically shows if the code was applied. Note: At the checkout read again if the discount...
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    Analysis Springer math books 40% off till Nov 30

    Springer math books are 40% off till Nov 30. Coupon code is MATH19PE. I bought Linear Algebra by Axler , the analysis books by Pugh and Abbott. Any further recommendations for good books?
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    Google's AI beats world Go champion

    Go has been considered one of the games in which the human is superior to any AI. However in a first match Google's AI has beaten world Go champion Lee Se-dol. Earlier this year the AI beat the European Go champion.
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    Meaning of in partial fulfillment

    Meaning of "in partial fulfillment" In a thesis one often finds this sentence: "A thesis submitted in partial fulfillment of the requirements for the degree of... ", e.g. here: What does "in partial fulfillment" mean, in...
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    TEDxCaltech: Lectures in honor of Feynman

    TEDxCaltech was an event at Caltech where invited speakers gave talks in honor of Richard Feynman. The speakers are experts in the fields of biology, physics and nanotechnology. Among the speakers are Leonard Susskind, Scott Aaronson, Sean Carroll and more. I can't even say which of the...
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    Bell's Theorem - Easy explained

    Last week I had a blast with reading explanations on Bell's theorem. It was the first time that I've actually understood it. So I wanted to share some websites that explain the theorem in an easy way: 1) Spooky Action at a Distance – An Explanation of Bell’s Theorem by Gary Felder This...
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    Hidden Variable - How to calculate the straight line

    There are plots that compare the expectation value E(a,b) of (i) a hidden variable theory (ii) quantum mechanics For example here: 1. Talk given by Alain Aspect, video at 2m28s 2. PF Thread: The Unfair Sampling Assumption & Bell Tests For the hidden variable theory the expectation...
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    Bending distilled water with static electricity

    You probably know how to bend water: Use a comb and rub it with wool (or just comb your hair) and hold it next to thin jet of water coming out of a tap. Here is a video: Comb with wool An explanation is offered here (the water molecule is polar). However, I remember my physics teacher...
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    Project Euler - What you've learned

    So I registered on" and I must say: it's quite addictive! I didn't expect it to be that much fun. I'd like to share what things I've learned from solving the problems: - When solving a problem you get access to a thread. I was impressed how different the...
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    Call by reference

    I am confused by two versions of call by reference in C++. As an example two methods that square an integer (CBR stands for Call By Reference): //Version 1 void squareCBR(int& x) { x = x * x; } //Version 2 void squareCBR2(int* x) { (*x) = (*x) * (*x); } Let's call the functions...
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    Arcade stick driver

    I have the Hori fighting stick 3 (arcade stick) that has a USB connection. It is meant to be used with the Playstation3 but I'd like to use it for the PC. When I connect it to the PC via USB it is recognized by Windows XP but in the "gamecontrollers menu" no button or stick movement is...
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    PC restarts everytime I watch a video

    My pc restarts everytime I watch a video after 5 minutes (e.g. on youtube or if I watch a video with the windows media player) . a) I've already done a memory test (the memtest ran for 6 hours and didn't show any errors) b) I formatted the hard drive and reinstalled windows XP...
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    Which RAM do I need?

    My 5 year old pc has 256MB ram and I would like to buy new ram (because with WinXP it runs very slowly). But I don't know which ram to buy. --- 1) I've installed the program "Everest" and it gives the following information: Motherboard Name: Asus P4S266-VX If i click on SPD Everest shows...
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    Congruences with fractions

    I have a question about congruences involving fractions. For integers a and b the following is defined: a and b are congruent modulo m (m is a natural number) if there exists an integer k such that k*m = a-b a \equiv b (\mbox{mod } m) \Longleftrightarrow \exists k \in \mathbb{Z} : km = a-b...
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    You're too much of a mathematician if

    You're too much a mathematician if ... Hi all, I thought it would be funny to open a thread like this. So feel free to post! You're too much of a mathematician if ... ... if you think that "epsilon < 0" is funny.
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    You're too much of a physicist if

    Hi all, I thought it would be funny to open a thread like this. So feel free to post! You're too much of a physicist if ... ...if you wear a T-shirt with the Maxwell equations on it. ...if you name your cat "Schrödinger". ...if you read "Quarkbällchen" and think of quarks. ("Quarkbällchen"...
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    Batman, Robin and Catwoman

    Batman walks 10 miles south, 10 miles east, 10 miles north and 10 miles west. He doesn't arrive at his starting point, but a little west to his starting point. Robin also walks 10 miles south, east, north and west. But he arrives a little east to his starting point. Catwoman walks 10 miles...
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    Parallel circuit with humans

    Here's an episode of brainiac, where they test how much an electric fence is shocking: Now at time index 2:21 they build a parallel circuit with humans. What I wonder about is why only the first two persons get strong shocks, while the others don't. Can...
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    Funny student comments

    Maybe you've already filled some of those evalution sheets where you have to comment on your professor's teaching style. This is a video of a professor who shows his students his "personal comments collection". [Broken]
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    How to write Math Proofs

    Below is a list of notes on mathematical proofs. The notes are directed at beginners who want to learn how to write mathematical proofs. PROOF TECHNIQUES 1) Introduction to mathematical arguments (by Michael Hutchings) [Broken] 2) How...
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    Big Oh notation (Landau symbols)

    I have a question with respect to the Big Oh notation, in which the Landau symbol O(n) is involved. The Landau symbol O(n) is defined as: f(n)=O(g(n)) if there exists an integer n_0 and a constant C>0 such that for all integers n \geq n_0, f(n) \leq C \cdot g(n). For example f(n)= 5 \cdot n...
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    Ribosomes, RNA and pseudoknots

    The article Danish researchers solve virus puzzle here describes how physicists and biologists work together to examine how viruses are produced by a cell. As far as I understand, every human cell has RNA which contains the 'recipe' on how to build proteins. The human cell also contains...
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    Group axioms - Verify?

    It is known that "the integers under addition" form a group, that is (Z,+). I have always wondered how to actually proof that (Z,+) is a group? Definitions for a group from wikipedia: I'm especially interested in two things...
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    Dishwasher - Voltage at metal cover

    My dishwasher in the kitchen has a metal cover inside and some persons got a small electric shock when they touched the metal cover with wet hands. So I took a voltmeter and measured the voltage between the metal cover of the dishwasher and the metal-washbowl (I suppose the metal-washbowl is...
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    EM wave - nodes at metal surface

    I've read in a book, that if you had a standing electromagnetic wave between two metal plates, only nodes would be at the metal plates. This is due to the infinite high conduction of metal, the book says. Why is that so?
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    Light heats up material

    Hello, why does light incident on a material heat up the material? :redface:
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    Red clouds

    I've often observed the sky in the late evening and it was dark. But on cloudy days, the sky is actually bright. The housetops appear dark compared to the sky. And the clouds appear in a dark red tone Anyone has an explanation for this? Does the light come from earth, from the moon or from the...
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    Electric discharge - Sound?

    Hi all, everyone has experienced electric shocks when discharging oneself, for example when you have clothes made of wool and take them off, or if you touch a metal object after walking across a carpet. My question: Why do you hear the discharge? I've noticed when getting the laundry out...
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    Two daughters in rivalry

    A father has two daughters who fight against each other the whole time. The father is so fed up of seeing his daughters in competition that he calls them. He wants them to come to a race track and tells them: "You've both come with your Ferrari and Porsche and you will race. But the car...
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    My Goals in Life

    "My Goals in Life" section Hello, I'd like to suggest opening a section where you can write your "goals in life". It could be for example put as an extra link "goals in my life" together with the journals, or if one clicks on a user's name. The reason is, I'd find it interesting to read...