Interesting Definition and 790 Threads

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...

Here is an article I think you might enjoy about a topic that has challanged us for years. Its on paradoxes in time travel explaining a lot of the problems involved. Here is the link... http://ezinearticles.com/?Paradoxes-in-Time-Travel&id=224204"

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...

Dear community I'm trying to get a grip on this integral: \int \frac{\sqrt{1-x}}{\sqrt{x}-1} dx. I tried substituting x=\sin^{2}(u), which leaves me (standing) with \int \frac{\sin(u)\cos^{2}(u)}{\sin(u)-1} du. But I just can't solve it, no matter which way I try. I would be thankful for every...

This project brings up an interesting legal dilemma with basic public key encryption and sharing digital copyrighted material: http://monolith.sourceforge.net/ ---------- Here is the basic gist: Let's say I have a copyrighted file that is represented by the following bit sequence...

I saw on this website http://www.fullmoon.nu/book/ A article about a Conversation with God that's the name of article. Its pretty interesting. Talks about god as a natural existence, http://www.fullmoon.nu/articles/art.php?id=tal this might be old here and sorry if it is.

OK, i built a computer for my step-brother today. After a lot of pain getting it to boot, i got it working. But in windows, the menu for safely removing hardware (like what comes up when you put a usb key drive in) comes up, and the main (only) hard drive is there. but in my computer, it...

Can anyone suggest ideas for interesting projects in Biology, preferably Botany. There should be some amount of practical work involved in it. It shouldn't go too complex like DNA fingerprinting, etc.

Two sides of a triangle have lengths a = 5cm and b = 10cm, and the included angle is \theta = \frac{\pi}{3}. If a is increasing at a rate of 2cm/s, b is decreasing at a rate of 1cm/s and \theta remains constant, at what rate os the third side changing? Is it increasing or decreasing? Just...

Hi all, Im a bit new to this forum. I will be going to university this September (Hopefully) and i decided to do a masters degree in Straight MAthematics. I have decided for some of my options that i will do some programming courses as i enjoy logic behind programming. But I am also...

We had to do a question in my Advanced Mathematics class, and the way that I did the problem was supposedly right. My teacher even did it that way. However, the answer was wrong, so my teacher showed us the correct way to do the problem. The dilemma I have is that BOTH ways should work, but...

I wasn't sure where to put this thread... if it's in the wrong place, please move it. Anyways, I'm making a couple of posters for display and one of the showcases is featuing antique equipment like ohmmeters (Wheatstone bridge), ammeters, voltmeters, etc. I was wondering if anyone knew of any...

Hmm...well, it may seem rather immature :redface: Using any quantity of (any) halogen and SPONCH atoms, draw a molecule of the molecular solid possessing the highest \frac{\text{Melting point}}{\text{Molar mass}} ratio. (Note: Diamond is not a molecular solid; it is a network solid) What...

hi I'm currently in yr 12 in my first year of the IB diploma studying higher physics. i have chosen to complete my 4000 wrd essay in this subject, but i can't think of a suitable research question. The essay can either be a simple written essay or an investigation/experiment. i would like to...

This isn't homework, but I'll post it anyways because I'd like to know. It's from Herstein's Abstract Algebra. Show that if u = 4n + 3, where n\inN, then you can not write u in the from u = a^2 + b^2, where a,b\inN. I feel silly for asking this, but I'm curious to know. The one thing...

I was reading over my Physics book during break, what a shock huh, during my break? lol. Well I ran across two questions that interested me, they are not homework problem but I was curious about them. So I thought I would see if anyone knew the answers. So here they are. 1) Why are the frets...

Hey guys, u know how Euclid proved that primes r infinite. Now knowing that primes r infinite, if we take some primes p1, p2, p3,...,pn then will p1*p2*...*pn(+/-)1 always be prime?

Hey everyone, I have a free response question concerning some rather simple mechanics presented in a ratheruh...interesting way. We have a block of mass M, that slides don a hill at an angle of theita. the block slides down the hill from rest at s=0 to the final position/distance s. Here's...

I just finished reading this paper, and have a question: CAUSAL SITES AS QUANTUM GEOMETRY J. DANIEL CHRISTENSEN AND LOUIS CRANE Abstract. http://arxiv.org/PS_cache/gr-qc/pdf/0410/0410104.pdf We propose a structure called a causal site to use as a setting for quantum geometry...

Interesting question about probability. Someone could help me to find the answer ? "One bus arrives in the bus station between [12:58 am, 1:02 pm] and wait 15 seconds before to go out. One man arrives in the station bus between [12:59 am, 1:01 pm] and wait 30 seconds before to take a tax...

Pharyngula has some exerpts from Jones Dover school board decision that impressed me as well and truly written: http://pharyngula.org/index/weblog/comments/the_bottom_line_in_dover/ http://pharyngula.org/index/weblog/comments/unconstitutional_to_teach_id/ in case these links are slow (lot...

Hi everybody, I was wondering if anyone can suggest any really interesting math problem, as I seem to have reached a point where I am tired of reading theory and need to focus on some serious problem. I have studied Calculus 1 and 2(=single and multivariable calculus for Real numbers) ,some...

Interesting question - Not homework! Show that the sum of the infinite series: log_2 e - log_4 e + log_{16} e + {(-1^n)} log_{2^{2n}} e ... equals \frac{1}{ln2\sqrt2} Any ideas?!

I'm looking at an integro-differential equation prompted by a HW question. This is a simplified version of it: \frac{df}{dx}=-\frac{af}{x^2}\left(\int_{x_0}^x u^2f(u)du+M\right);\quad f(x_0)=1 with: x_0>0 and a and M positive constants. Does anyone know if it can be approached...

Here’s a question for you all… but first some background (see jpeg attachment for sketch) Assuming all surfaces are frictionless (5kg on horizontal surface, two 2kg blocks on 5kg block), and the pulley has no mass, with what horizontal force applied to the 5kg block will the two 2kg...

Do any of you guys have a favorite state? A least favorite state? Commentary to make about strange things you see in particular states? For me, I have to start off with three tidbits: 1) The I-40 in Arkansas is of less quality than clay roads I've seen on Indian reservations, so what the...