Search found 8518 matches

Wed Jun 13, 2007 3:17 pm UTC
Forum: General
Topic: Where were you when you heard about 9/11?
Replies: 231
Views: 19690
I was in the army in Israel. We kept switching each other on our posts so we could go watch it on TV.

I was pretty amazed. And I also thought it might be a trigger of some sort to the US... Guess I wasn't wrong.
Mon Jun 11, 2007 7:26 am UTC
Forum: Science
Topic: Useful maths?
Replies: 36
Views: 6951
I study both physics and math in the university. Calculus is important, certainly. And it would be nice to know when you can really change a sum into an integral or change the order of sums etc. But that usually helps in actually solving problems. Without a doubt, the most helpful and important subj...
Mon Jun 11, 2007 7:21 am UTC
Forum: General
Topic: So I was watching Batman.
Replies: 48
Views: 5576
A friend of mine told me how there was a difficult problem in math he couldn't manage. Then, while sleeping, he dreamt himself solving it (many epiphanies ensued).

When he woke up he recreated the solution and discovered it was massive amounts of gibberish.
Mon Jun 11, 2007 7:09 am UTC
Forum: General
Topic: What is the most amazing thing you have ever seen?
Replies: 99
Views: 15511
There's quite a bit of amazing things I've seen, I think. Going stargazing is incredible. I can sit for hours just staring at the milky way. Fire is awesome. I love fire. And also, water ripples. We have this sort of flat circular plate with edges, about 1 meter in diameter in our yard. In the winte...
Sun Jun 03, 2007 3:52 pm UTC
Forum: Mathematics
Topic: Seemingly prime
Replies: 28
Views: 5805

Seemingly prime

There are some numbers people mistake for being prime. The best example I can think of is 91.

It's odd, it isn't divisible by 3 or 5, it's not that high, but wait - it's 13*7. Any other examples?
Sat Jun 02, 2007 8:53 am UTC
Forum: Mathematics
Topic: A debate over some simple probabilities
Replies: 48
Views: 8388
I think you got a good enough answer already (if you asked what are the chances to pick this specific table twice, it's 1/2500, if it's to sit twice at the same table it's 1/50). I just thought to mention that everyone assumes a uniform distribution on the tables (not that it matters for the sake of...
Sat Jun 02, 2007 8:47 am UTC
Forum: Mathematics
Replies: 92
Views: 19896
17, definitely.
Sat Jun 02, 2007 8:43 am UTC
Forum: Logic Puzzles
Replies: 20
Views: 5400
Never heard of it before but I don't see what's the problem... I think the catch is how you display the predictor. If he is 100% infallible, then you should choose box B and be done with it - he'll have said to choose box B and you'll get the 1 mil. Why go for the both option? What's paradoxical abo...
Fri Jun 01, 2007 9:02 am UTC
Forum: General
Topic: Whats red, white and yells a lot? [Trigger Warning]
Replies: 130
Views: 21921
Well if you insist on an Israeli guy telling holocaust jokes: Two kids are in Auschwitz, getting out of the line for bread. Suddenly a third kid runs up to one of them and steals his load of bread. The second kid asks "Why aren't you running after him?" so the first says "Don't worry,...
Thu May 31, 2007 5:17 pm UTC
Forum: General
Topic: Is dark humor funny?
Replies: 2
Views: 894

Is dark humor funny?

These are two of my favorite jokes in recent time. They would probably be considered gory/dark. What do you think? What's red, silver, and bumps into walls? A baby with a fork stuck in its eye. And the second: What's the difference between a truck full of sand and a truck full of babies? A truck ful...
Mon May 28, 2007 9:22 pm UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 447355
A friend of mine always wanted to create a matrix called MIT so he could calculate its kernel - kerMIT
Sun May 27, 2007 8:00 pm UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 447355
Two calculus jokes (bad enough that they're good?): All of the functions are at some party. Suddenly the door opens and derivative enters. All of the functions start running outside and shouting "He's going to derivate me! He will!!". Only one function stays put and looks around smirking. ...
Sat May 26, 2007 10:43 am UTC
Forum: Mathematics
Topic: Favorite math jokes
Replies: 1452
Views: 447355

Favorite math jokes

A farmer is asking an engineer, a physicist and a mathematician to build the most efficient fence around his flock of sheep. The engineer builds a square fence around the sheep and says "That's the best I can do". The physicist wraps a fence around the equator and slowly shrinks it until i...
Sat May 26, 2007 10:33 am UTC
Forum: Mathematics
Topic: About how math is taught. (Or: People who "can't do mat
Replies: 138
Views: 20585
Obviously I don't think math should be taught by someone who isn't enjoying it. Two points to consider: What's taught in school isn't math. It's some numerical exercises but it holds nothing of the beauty of math. The only thing that comes close geometry where you have to prove various things. Howev...
Thu May 24, 2007 8:49 pm UTC
Topic: Freedom of choice
Replies: 67
Views: 10149

Freedom of choice

Hi everyone. I personally don't believe in freedom of choice. My reasoning is mostly psychological (maybe you could even say biological) and is as follows: 1. Human beings want things. They have various goals, either a finite or infinite number of them, some are "earn a lot of money" and o...
Tue May 22, 2007 12:16 pm UTC
Forum: Logic Puzzles
Topic: Building puzzle
Replies: 2
Views: 1902

Building puzzle

This is a really cool puzzle: http://www.mathsnet.net/geometry/solid/houses.html?Text1=jp It didn't take me that long to solve the whole thing, less than half an hour, maybe not less than 15 minutes. If anyone knows any puzzles similar to this, please post them, I liked it a lot. I had a method whic...
Sat May 19, 2007 6:11 pm UTC
Forum: Science
Replies: 14
Views: 5250
The point of discussion is that, seeing as there has been a universe for 15 billion years or so, there could easily be very old civilizations (if, and that's a big if, civilizations don't destroy themselves always, eventually). Such old civs may need to build vast structures in order to support them...
Thu May 17, 2007 1:55 pm UTC
Forum: Science
Replies: 14
Views: 5250

It revolves around estimates of probability of extraterrestrial life in the universe (those being high according to said estimates) and the lack of evidence of ET life - no huge stellar or galactic complexes, no probes, no radio signals and so on. Or, in the words of Fermi "Where are they?"...
Mon May 14, 2007 4:51 pm UTC
Forum: Science
Topic: Tell Me How To Teach Myself Physics
Replies: 38
Views: 12190
In my thermodynamics test I got the lowest score I ever received - 15 (out of 100). Truly pitiable. However, for what I can only say are "historical reasons", every course has a make up exam, on that one I improved to an 85...
Mon May 14, 2007 4:48 pm UTC
Forum: Science
Topic: FanSci: Silver and Iron - Weaknesses of Mythical Creatures
Replies: 73
Views: 15663
Which probably points to a rule: devices that work against the common vampire / werewolf / fae tend to fail more often the closer you are to an important character. Narrative takes precedence over pseudo-scientific explanations. It's the same way with special moves in games. If you use the same mov...
Mon May 14, 2007 8:57 am UTC
Forum: Mathematics
Topic: Matlab guide
Replies: 3
Views: 2040

Matlab guide

Hi everyone. I have a project for uni to do in Matlab, which I know nothing about. I was wondering if someone could point me to an easy to use guide. The most important functions I need to use are finding numerical solutions to PDEs and then manipulating them (normalize them according to their maxim...
Sun May 13, 2007 1:39 pm UTC
Forum: Science
Topic: FanSci: Silver and Iron - Weaknesses of Mythical Creatures
Replies: 73
Views: 15663
I never understood why in vampire-related franchises there aren't more sophisticated weapons. I hear Blade had some, but I didn't see it. Also, Alan Moore had a character in a comic book he wrote (Top Ten) bless the rain when vampires attacked the populace. But really, wouldn't some sort of holy wat...
Fri May 11, 2007 12:26 pm UTC
Forum: Science
Topic: Tell Me How To Teach Myself Physics
Replies: 38
Views: 12190
Our physics syllabus includes (roughly, without laboratories and math courses): Classical mechanics and electrodynamics Waves and optics. Analytical mechanics (if you've taken a course in variational calculus, it's basically the same) and electrodynamics. Thermodynamics and statistical physics. Two ...
Fri May 11, 2007 11:58 am UTC
Forum: News & Articles
Topic: My favorite things!
Replies: 4
Views: 3206
Ah, I'll know for next time, I wasn't sure where it should be posted...
Thu May 10, 2007 12:12 pm UTC
Forum: News & Articles
Topic: My favorite things!
Replies: 4
Views: 3206

My favorite things!

How can you resist a combination of a Rube Goldberg and fire? Really, someone must have read my mind.

http://funhouse.bubble.ro/832/Pyromaniac_Version_of_Rube_Goldberg_machine/
Thu May 10, 2007 12:02 pm UTC
Forum: Science
Topic: Is there hope for poor old me?
Replies: 30
Views: 6307
Wow Herman, that's pretty cool. I may steal some elements from the plan to myself.
Wed May 09, 2007 11:56 am UTC
Forum: Science
Topic: Planetary Orbits
Replies: 14
Views: 7793
It's not very simple at all. There are no conclusive theories regarding the creation of solar systems. There were some theories before the discovery of other planetary systems, but those theories failed once we found solar systems with Jupiter-sized planets closer to their sun than our Earth's orbit...
Mon May 07, 2007 1:41 pm UTC
Forum: Science
Topic: Is there hope for poor old me?
Replies: 30
Views: 6307
I'm finishing up my math and physics degree at the university and I have similar questions... When I started it I just said "I'll learn what I enjoyed in school". From what I gather - there are plenty of uses for physicists, in all parts of industry - optics (including photography and so o...
Thu May 03, 2007 10:34 pm UTC
Forum: Mathematics
Topic: The number i
Replies: 57
Views: 16634
Just to clarify my point since it seems I was misunderstood. Imaginary and complex numbers are immensely useful when calculating many many things. However, as far as actual measurements are concerned, in physics (in my experience, which isn't very vast, but greater than most people's), all measureme...
Thu May 03, 2007 1:12 pm UTC
Forum: Mathematics
Topic: The number i
Replies: 57
Views: 16634
Regarding i in physics, I don't know of anywhere in physics where you actually need i. It certainly is very useful, for example in quantum mechanics, but eventually, you only measure real numbers, and you an do all of the calculations using real numbers.
Sun Apr 29, 2007 9:58 pm UTC
Forum: Logic Puzzles
Topic: Ants on a stick
Replies: 16
Views: 5677
Yes, the ants have zero length. It's like that joke about the physicist who was asked to create an ideal horse racetrack. He begins by saying "assume a spherical horse with no legs". BTW, even if a collision is guaranteed, 1 second isn't a lower bound (for example, a case where the ants st...
Sun Apr 29, 2007 6:52 pm UTC
Forum: Logic Puzzles
Topic: Ants on a stick
Replies: 16
Views: 5677

Ants on a stick

Doesn't sound very appetizing, does it? Suppose you have a 1 meter long stick. On the stick are ants, randomly placed and facing left or right randomly. Each ant moves at 1 meter per second. Once two ants collide, they reverse directions. When an ant reaches the end of the stick, it falls off. Find ...
Sun Apr 29, 2007 5:23 pm UTC
Forum: Logic Puzzles
Topic: Graphical riddle
Replies: 24
Views: 7113
About the difficulty level: Obviously the first two parts are very easy. The third is hard. Most people usually struggle for several minutes with the third one, at least. Then, when you ask them to do the last part, their mind is set that "the next part will be even tougher" that usually t...
Sun Apr 29, 2007 2:50 pm UTC
Forum: Logic Puzzles
Topic: Graphical riddle
Replies: 24
Views: 7113

Graphical riddle

Hi. The most important thing with this riddle is to do it in the order it's written. You kind of ruin it if you skip parts. Also, please try and read the next part of it only after completing the previous one. I guess it works better when it's told in front of someone, not online... It starts off ea...
Sat Apr 28, 2007 11:06 am UTC
Forum: General
Replies: 3985
Views: 636974
Hi everyone.

My name is Zohar, I'm 24 from Israel. I'm studying math and physics at the university. xkcd is my favorite webcomic and I just now decided to join the forums.

Zohar
Sat Apr 28, 2007 10:57 am UTC
Forum: Logic Puzzles
Topic: Unusual Paragraph
Replies: 36
Views: 8294
The amazing thing is, someone once wrote an entire book in French with that same trick. Even more amazing, it got translated to English, again using the same trick.
Sat Apr 28, 2007 10:54 am UTC
Forum: Logic Puzzles
Topic: Handshakes
Replies: 7
Views: 4016
The solutions aren't exactly different, simply different ways to look at the problem. It's interesting to see what people try first. Here they are: 1. Write down 10 points on a piece of paper and try to connect them appropriately. That's kind of insane, I think, though I never tried it myself. 2. Th...
Fri Apr 27, 2007 8:59 pm UTC
Forum: Logic Puzzles
Topic: Handshakes
Replies: 7
Views: 4016

Handshakes

Hello everyone. I'm new to the forums but I've been loving XKCD for a long while. This is one of my favorite riddles. A professor and his wife (don't ask me why it's not a professor and her husband, that's just how I heard the riddle :-) ) are at a party. In the party there are 4 more couples (overa...