Interesting Definition and 754 Threads

I am really sorry for posting this general topic here :redface:; I couldn't find any other place. So, here's what I observered: The rate at which new people join this forum is exceptionally high during this time of the year. So, just wondering why?

http://backreaction.blogspot.com/2007/07/consistency.html Bee took the time to write a thoughtful essay about general relativity and why you might or might not want to quantize it---and some broader thoughts about theories (what their limitations are, how you verify them.) Perhaps I am not...

Homework Statement For what natural numbers n is (10^n)-1 divisible by 73? Homework Equations N/A The Attempt at a Solution I have already found that it holds when n is a power of two greater than 8. (That means when n is great than 8, not the eigth power of 2) What other natural...

The textbook states something along the lines as prove the identity. 1 - ((sin^2x)/(1+cos x)) = cos x If you want you an work this out algebraically relatively easily to get cos x = cos x. But what if you put pi back into the original equation? You get 1 - undefined = cos x. So I graphed...

1. The A mathematically inclined friend emails you the following instructions: "Meet me in the cafeteria the first time after 2:00 p.m. today that the hands of a clock point in the same direction." When should you meet your friend? 2: : (hr : min : sec) I have attached my attempt at a...

"Yes, when I take my dog for a walk," said a mathematical friend, "he frequently supplies me with some interesting puzzle to solve. One day, for example, he waited, as I left the door, to see which way I should go, and when I started he raced along to the end of the road, immediately returning...

If you have a chain of links of equal lengths whose ends are connected (so that it forms a loop) then by holding three points and "pulling" them outwards different triangles can be formed. For example, with a chain that has three links 1 triangle can be made. With 4 links no triangles can be...

Which state in the USA is the most interesting one to live in, in terms of having things to do and see?

so I'm having trouble with an integral. However I noticed an interesting property to it.int{gdu}=c*int{gd^2u} with the integral being from -infinity to positive infinity. The problem arose while I was trying to solve the schroedinger equation in the presence of a potential, I'm trying to...

we have to prove that 10+100+1000+10000+100000+...=-(1/9) any ideas?

Hi... Many times I have read articles about how strange inertia is and that no theory we have so far can not explain it etc. However I don't see that problem with it. What is so weird on inertia? It seems to me as normal thing that if some reference frame accelerate the particles in this...

Greetings, I learned that the speed of gravity is the speed of light as einstein predicted that once the sun disappears, the Earth would not instantaneously fly out of its orbit but only after an approximate 8 mins then the Earth would spin out of its gravitational field tangent to the circle as...

This is a problem was thinking about. If I have a capacitor and fill it with a dialectric of some dialectric constant (the dialectric fits perfectly and is mounted via a frictionless bearing so it can move freely). How fast does it move?

Homework Statement There are n > 3 points in the plane such that any three of the points form a triangle of area \leq 1. Show that all n points lie in a triangle of area \leq 4. Homework Equations None. The Attempt at a Solution This is hard to discribe since it is...

http://motls.blogspot.com/2006/12/lorentz-violation-and-deformed-special.html

I don't like electronics at all.However,it's an interesting question.For OR operation standard circuit,there are two diodes which are forward biased in 1-1 state.I cannot draw the circuit here;but anyone familiar to the circuit undearstands that even if the two diodes were not there, the OR...

Interesting lemma If P.Ferma knew the proof of the following lemma "Lemma. If numbers a, b, c, have no common factor, numbers c-a and c-b are also mutually-prime and n is odd, then the numbers (c^n-a^n)/(c-a) and (c^n-b^n)/(c-b) are also mutually-prime", then with its aid it is possible to...

Hi, I was wondering if anyone could give me some advice as to how to go about this. This seems like it might fit under more than one discussion category, but astrophysics seems like it might be the best place. I'm a programmer, and what I am trying to do is to write some software to generate...

Find a general equation of geodesics on cylinder's surface. What's the name of these curves? :cool:

Hi Everyone, I think I've solved the equations of motion for a particle in this one-dimensional potential - V(x) = -k/(a-x) - k/(a+x) with |x| < a, a is real +ve, x is real. K is a constant of suitable dimension. It's a charge between two like charges with separation 2*a. I start...

I have some quotes from various books I have read recently, that I would love to hear your thoughts on: Richard Feynman: "All these [chemical] rules were ultimately explained in principle by quantum mechanics, so that theoretical chemistry is in fact physics. On the other hand, it must be...

Interesting Question... If I were to tie one end of a rope (a very very long rope) to the ground and the other end to a rocket, and fired the rocket into space, would the rope stay in orbit without falling back down to earth? Assume once the rope was fully vertical that the rocket was...

Hey guys I have an interesting topic for all of you who interested. From the EPR paradox we know that principle of non-locality indeed exist and yet it is suggests that information cannot be transferred between A and B due to quantum mechanics uncertainty principle since information gets...

Today my wife and I got into a little discussion on calorie intake and weight gain. A dietitian will tell you that if you take in an extra 3500 calories a day in your food, you will gain an extra 1lb if you do not burn off that 3500 calories. This is usually true, since there is no food out...

JB diary for December already has some intriguing thought provokers. he often has different takes on things, or he implements his takes with different pictures and quotes from other people. So here he is reflecting on "virtual worlds" and "singularity"(yes?)(no?)(other?)... Also it is...

Interesting problem I came across, yet I'm having some trouble with it: Here are a few of the next generation of experiments currently being planned for constraining cosmological models. Not all of these are groundbased: DES:https://www.darkenergysurvey.org/"...

Hi, I was interested in writing a technical paper related to aerodynamics but the whole subject seems so vast. I'm finding it hard to zero in on a topic which would be technically interesting at the same time important with respect to the current practical requirements of planes. Would...

Preface:The best way I've been taught how to prove that a force is conservative is to take the curl of the force and show that it is equal to zero. That's pretty quick, but after studying for a complex analysis midterm this idea struck my mind. I'm not a master of complex analysis, so there...

We all know that 45 degrees is the optimal angle for range when launcing a projectile: Does this angle change when adding air resistance? If you know the answer please respond, If you don't, please go away rydogg

A friend recently made this statement: "An object cannot travel faster than c". I am unable to find any evidence supporting this statement. Comments?

Sorry if this is kind of vague, but the other day, one of my math profs told me about a theorem which he thought was particularly interesting. I might be missing or getting a condition wrong, but here goes: Suppose I(f, d) is a real-valued function, where f is a real-valued function always...

I will start with the one that I have worked out already. I am submitting the answers to an online testing site and the answer that I have submitted is wrong but I believe that my math and selection of proper equations is correct. THE QUESTION: A pellet gun is fired straight downward from...

Wells' "Dictionary of Curious and Interesting Numbers" Does anyone have a copy of Wells' "Penguin Dictionary of Curious and Interesting Numbers" 1986 or 1987 edition? I'm curious about how they compare to the revised (1997) version I have. On a lark, I decided to put together a list of...

"Annie and Evelyn observe that, on average, it takes approximately 10 days for a small glass of water to completely evaporate when left outdoors. What would they estimate for the average annual precipitation on Earth?" (Answer in depth of precipitation) Here's my though process but I have a...

F=ma a = F/m Light's mass: 0 N = infinite acceleration? :rolleyes:

Hi, So this is the problem out of Fundamentals of Physics by Haliday Resnick and Walker (Seventh Edition. By the way this problem would all under a first year calculus based mechanics course. I know calculus through multivariable...but that's not needed for this...

Okay, maybe not great marks for technical merit, but high marks for style and definitely very high marks for dedication. What a trooper! http://www.thesmokinggun.com/archive/0411061foot1.html (Click the picture for the video)

interesting problem! 1) Find the normal vibrations of a fluid put in of an sphere . ray of sphere = a.

What is the oldest man made thing you own? i love antique furnature, vehicles and gizmos, my cott would be full of the stuff if i had the money, most of the time i could not explain why i like antiques, may be it is the patina or the touchy feely thing, when my bike is finished i intend to buy...

I thought about this outta no where. I want to make a casino game where the odds are against the house, but the catch is that the game rules force the player to play until the odds change against him. For example, make the odds 80% against the house (player has 80% chance of winning). If the...

Unstable fixed point...help me!...U may find interesting! Dear friends, I have a 3-D non-linear equation. I have inearised it to get a single fixed point which turns out to be a repelling spiral (one +ve real eigenvalue, and two complex conjugates with +ve real part)...Now, the problem is...

http://www.spikedhumor.com/articles/39165/No_Science_No_Benefits.html How truthful is this video? Any opinion?

This is probably in the wrong section. Anyway, McGill's starting an 'undergrad math magazine' in which I want to contribute a little something I came up called 'Crossnumbers' in its recreation section. The idea is really self-explanatory. I've come up with a few 'interesting' integers already...

There was an interesting conversation at Distler's blog between the owner and fh. I thought really thought-provoking points were raised. I would like to copy some sample exerpts here. the main address for Prof Distler's blog is: http://golem.ph.utexas.edu/~distler/blog/ This particular thread...

I found a company makes interesting kids toys. For kids that have trouble catching baseballs, there's the ball of nails, includes a separate crow bar like tool for removal of the ball from small hands. A halloween favorite is the captain elmo space helmet, bascially a plastic bag and a...

Hi! i have a Qns, and i got it from a reference book(physic). Many capable investigators, on the evidence, believe in the reality of extrasensory perception. Assuming that ESP is indeed a fact of nature, what physical quantity or quantities would you seek to define to describe this...

For a planet of radius a, find the area of the surface between the equator and latitude 60 degress north. This problem was posed to me way back in my calc II class. Instructor (somehow :wink: ) used series to solve it, then asked us if we could solve it differently. I only vaguely remember...

Hi, I have an assignment from my Chemistry class which is supposed to be done during my Spring break. The question is to CALCULATE the annual production of CO2(carbon dioxide) in metric tons by all humans in the world from breathing. The assumptions are: 1. The composition of exhaled breath...

http://www.defensetech.org/archives/002286.html This comes from the concept discussed - using plasmas on the skin of aircraft to reduce drag and to reduce the RADAR signature - which is an idea known to serious UFO researchers for some years now. I think it is likely that this technology has...

i have some queries..i was trying to find out some commands in the manual.. like,, --what command can be used for compressing files in Linux.. --how to check man page for /etc/passwd ? --and i am not clear with this uid command? why is the "set uid bit" set for "su" command? --and...