Important Definition and 498 Threads

Definitely a must see. This movie was shocking. Some of the things food companies are getting away with and how they are able to write our laws is incredible. If you care about your health and what you eat, definitely see this film.

I am interested to know whether it is important for engineers to get good grades when pursuing a MEng in Engineering, ie a terminal degree with no further phD studies. Are academic grades as important as in college (when they played a significant part of grad school entry) for employers or will...

Homework Statement The proposed design for an energy- absorbing bumper for a car exerts a decelerating force of magnitude bs + cv on the car when it collides with a rigid obstacle, where s is the distance the car travels from the point where it contacts the obstacle and v is the car's velocity...

Ed Witten was essential in organizing the 1 million dollar prize for clarification of the mass gap in QCD that is offered by the Clay institute. But why is this issue so important? Wouldn't all the successes of QCD stay also if no glueballs existed? Can somebody explain why Witten wants the...

I had a question about how the RNA processing occurs. I know that the RNA is transcribed off the DNA, and then the introns are removed(sometimes in different orders), and then the capping occurs. My question is whether or not different segments of RNA can fuse together before during the...

I suspect this is a very stupid question but: Why is voltage across a component (say, an LED) important? Isn't current the only important factor? If it says on the package 2.1V, 20mA. What does this mean? Does it not matter if I connect it to a voltage of 5V over 250Ω or 3V over 150Ω...

The poll is set up to accept multiple choices. Check off the paper or papers you predict will have the most significant impact on future QG research. If you have one that is not on the list, post the arxiv link, title and author(s) on this thread, to be counted as a "write-in". 1. Loop quantum...

Lately, I've been trying to learn as much as mathematics as i can, but i have been also trying to find out what order i should learn it in so that when I'm learning a new thing i won't get stuck because i didn't learn an important part of it. For example, i don't want to be learning calculus but...

I'm not getting much sun here so I checked my Vitamin D levels some time ago. They determined 16 ng/ml for Vit D 25 and 47 ng/l for Vit D 1,25 Apparently the first value signals a deficiency, but not the second. I read one should usually do only the first check (as it's cheaper), but on the...

I plan to focus on Gentics, and I am just finishing my freshman physics, I haven't got to my bio or chem classes yet.. So I was wondering, how important is physics and our understanding of it, if we want to go into the field? I can do pretty decent on the tests and understand the formulas and...

Here our last MIP poll: https://www.physicsforums.com/showthread.php?t=282166 By the end of this month I'd like to have a short list of promising first quarter papers. Ones that appeared Jan-March 2009 and stand a good chance of turning out to be important or valuable for future research...

Will not taking math classes beyond what's required for the physics major hurt me when trying to get into grad school for physics? At my school the only required math classes for physics majors are calculus I, calculus II, multivariable calculus, and differential equations. Also I've taken a...

Hello all, I'm entering my second year of university (Physics/mech engineering major) and am wondering whether it is worthwhile spending money on the textbooks? In my first year, I found there were some subjects where I didn't touch the textbooks - primarily Calculus I and II (Calculus...

Research, GPA, recommendation, GRE, etc.. There are many things to go to grad. Which one is the most important? One of my friend had very good GPA, but he did not get admission from any schools. His GPA was 3.95. Actually, his major was BIO, and he got all As from major, and only one B...

Why? (please read, this is the most important question i ever MADE!) Homework Statement Everyone know Earth orbit the su, however the orbit is not a full circular, but an oval... however then why won't Earth get stick into the sun? (when it get the close to sun?) where did other force that...

Hi everyone, I just watched an interesting talk from string theorist Brian Greene and he said something that really captured my curiosity. He mentioned that in the universe there is a list of about 20 incredibly important numbers that we have measured extensively. He then says that if those...

Even in my second semester of calc I have yet to see a situation where the extra step made any sense why is it important to write \frac{3\sqrt{13}}{13} instead of leaving \frac{3}{\sqrt{13}}. Its not a big deal but even my profs say its not that important so it has peaked my curiosity.

That's what my Precal teacher said, and so far I agree with him (though that's not saying much as I've only been exposed up to Precal mathematics). Do all of you mathematicians agree?

The poll allows multiple choices...which are your picks for the 2008 papers likely to prove most valuable to future research? The Uncanny Precision of the Spectral Action Ali H. Chamseddine, Alain Connes http://arxiv.org/abs/0812.0165 Loop Quantum Cosmology: An Overview Abhay Ashtekar...

Please help me solving this homework! 1. List three reasons why knowing the speed of sound is important to your life? 2. From at least three sources, gather information on how you can measure the speed of sound. then, describe the methods that are available to you. Information can be...

Hello, I am second year engineering physics major looking to go to grad school for either physics or nuclear engineering. Unfortunately my freshman year I decided not to do the honors curriculum because I had only took very basic high school courses and didn't feel prepared for it. How...

What was the the most fascinating or most important thing you've ever learned in Mathematics? For me the most amazing discovery was probably Calculus, and the introduction to graphs of functions. The most important thing I've learned in my life, is definitely Algebra.

So the topic is kind of vague, but allow me to expand: I'm applying for 10 summer REU programs for next year and I was wondering just how important the "memberships" category of my cv is. If I were to lay down $70 for a membership in both the Planetary Society and also the Seti Institute...

I'm a first semester junior with a current gpa of 2.77; my organic series last year really hurt me. I believe at the end of this semester I may be able to pull a 2.9 and after the spring a high 2.9, low 3.0. In addition, I plan to engage in undergraduate research. Assuming that I maintain that...

Which of these 3rd quarter 2008 papers do you predict will prove most valuable to future research? Significant papers tend to be cited more in subsequent research---we will soon have citation counts to go by, on some of these, as well as subjective judgment. Polling let's us share information as...

very important... at any group G show i)o(ab) = o(ba) ii) o(a) = o(cac^-1) c in G please i want solving

Starting from the equation dE=tdS-PdV+\mu dN It is straightforward to derive all 8 possible thermodynamic potentials. My question is the following: Why are the only important potentials Entropy Helmholtz free energy Enthalpy Gibbs free energy Grand potential ? Why aren't the other three as...

Hey guys, I have no background in physics but have been interested in time dilation for a while and have understood the concept without getting technical... My question is this... this is the atomic clock experiment... Suppose there are only 2 living beings in the universe ... one...

I'm an Engineering Physics Major senior and I'm going to get my Masters in Mechanical Engineering. I have an internship in the Polymer and Coatings Department Analyzing Data. I am mostly going to be doing Fast Fourier Transforms and studying the data. The problem is I don't really know...

I know the conflicts between Israel and other Arab and middle eastern countries have been mentioned many times in PF. Rarely is it ever mentioned why we should continue supporting Israel . Since the 1970''s , the United states has given is a total estimate of 1.3 trillion dollars of taxpayers...

Do you think school should integrate classes that promote mental math and mental arithmetic, for example the ability to multiply two digit numbers in your head (say 15x19 or 14x17, etc). These things are critical and many people can't do them with severe brain gyrations! Do you think enough is...

Prompted by D H's post on inertial forces … … I've just read the fascinating wikipedia article on http://en.wikipedia.org/wiki/Fictitious_force" . I hadn't previously understood how important Coriolis force is, even over small distances. :redface: Coriolis force is (minus mass times)...

I'm asking because I'm going to be a senior next year and I really, really don't want to take AP Literature. I loathe English with every fiber of my being. I'm also taking German IV which I've heard is mainly going to be a writing/literature class and I don't think I can handle two similar...

Hey guys, next week I'm writing a very important test, so it would really help me if someone could solve the exercises. Here it is:

How can we justify that one life is more important than Another's? I've been wondering about this for a while now. I've tried tackling this from a religious and scientific standpoint. For religion I've looked at the Indian Caste system and at the Christianity belief that we should put...

Hi, May be a trivial question. But, "Why angular momentum is an important physical quantity in quantum mechanics?". Could anyone explain me?

Alright, so I'm about to take the AP Calculus AB Test (the College Board one, of course), but I have a question: Am I allowed to have any Calculus applications on my calculator? (My calculator is a TI-84 Silver Edition Plus, and it is approved.) I have a Calculus application that can do several...

Very important... Let R denote the set of real numbers. Find all nondecreasing continuous functions g : R → R such that g(x+g(y))=g(g(x))+g(y) for all x,y∈R

Very important! Homework Statement If A is an symmetric operator in separable hilbert space (H) and 1)A>=0 (which means that (Ax, x)>=0 for any x) 2)A(H) is a closed set How do you proove that \sqrt{A}(H) is a closed set Homework Equations The Attempt at a Solution Facts...

How important is practical experience with quantum mechanics for understanding, as best as one can, the subject? For example: Weinberg in his QFT tome, briefly discusses QFT three point interactions in terms of angular momentum states. So, he points out that the interaction can be formulated...

Which of these first quarter 2008 papers/presentations do you expect to contribute most to future research? 1. http://cift.fuw.edu.pl/users/kostecki/zakopane08/rovelli.pdf Looppy & Foammy: at long last, falling in love Carlo Rovelli This is Rovelli's report at the March 2008 Zakopane...

I love doing proofs, but hate doing computational questions. If I become very good with proofs but remain just so-so with calculational problems, can I still become a good mathematician? My favourite subject is topology.

If I take general chemistry 1 and 2 is that enough? I want to take more higher chemistry but in order to do that my school requires I need to take 3 semesters of organic chemistry -_- So how important is chemistry for this major?

Homework Statement I really need help with this problem. The question is: Each side of an equilateral triangle measures 3.61cm. A charge of -0.34mC is placed at each vertex. what is the potential difference at the midpoint of the base of the triangle? Homework Equations V=kq/r [b]3...

Homework Statement During the action potential, Na+ ions move into the cell at a rate of about 2.98×10-7mol/m2/s. How much power must be produced by the active transport system to produce this flow against a +25.2 mV potential difference? Assume that the axon is 11.7cm long and 19.6um in...

Hey. I'm teaching (trying to) myself calculus before i go to college. The book i got from my trigonometry seems pretty repetitive, but I was wondering which topics i need to learn. So far, I've learned limits, derivatives, applications of derivatives (I wasted about a month on the chapter...

Hi I'm studying maths, further maths, physics and chemistry A levels and I was just wondering which of them are the most important if I take up engineering. I think I can get an A in maths and possibly further maths, but I'm struggling with our physics syllabus and predict myself a C or below...

Dear all. My question, is about "Virtual Particles". I've read, that they appear out of nothing, and disappear in a very short time. How could this happen ?! How can something come from nothing ?! Or how can something go to nothing ?! What is nothing then ?! Does this violates...

I'm an aerospace engineer, currently job hunting, but I'm keeping myself occupied by refreshing my memory in c++ programming. I've had a course on it, but that was a few years ago, and I have mainly been using Matlab instead (for about 4 years now). I wanted to know, as...

Hi guys i must write about th PROTOCTISTA I must include the nucleu, starch granules, chloroplast etc. all of these I must explain what they do in the Protoctista... But I can not find the "STARCH GRANULES" PLEASE HELP ME CAN SOME one give me an Advice where I can find it... I was in...