## Search found 138 matches

Fri Jun 20, 2008 12:44 am UTC
Forum: Mathematics
Replies: 18
Views: 2469

This is called "steady state" because of what occurs if the differential equation is set equal to some function of time rather than to 0. If the function is a constant, subtracting that constant from both sides gives an equation similar to the original. That equation will have a similar so...
Mon Jun 16, 2008 8:58 pm UTC
Forum: Mathematics
Topic: Majoring in Math
Replies: 48
Views: 7807

### Re: Majoring in Math

Don't worry too much about calc. It's in the program when it is because that's what the physics and engineering departments want, not because it's that central to math.
Sun Jun 15, 2008 4:06 am UTC
Forum: Mathematics
Topic: How much of a math nerd are you?
Replies: 95
Views: 9685

### Re: How much of a math nerd are you?

While Indon 's described system seems to be a variation of the factoriadic idea, his proposed program: I was thinking more along the lines of, "All rational fractions can be described in a limited number of digits, and some irrational numbers could be described as repeating digits." Don't ...
Sun Jun 15, 2008 3:15 am UTC
Forum: Logic Puzzles
Topic: another "what is the sequence" puzzle
Replies: 17
Views: 3977

### Re: another "what is the sequence" puzzle

Token,
Remembering Kekule, perhaps it would be better if you got some more sleep.
Tue Jun 10, 2008 12:19 pm UTC
Forum: Logic Puzzles
Topic: Avoiding the Librarian's attention
Replies: 18
Views: 3480

### Re: Avoiding the Librarian's attention

For anyone who hasn't noticed, the OP diagram has been edited (justified).
Sun Jun 08, 2008 3:20 am UTC
Forum: Logic Puzzles
Topic: Synchronized Randomness?!
Replies: 14
Views: 2288

### Re: Synchronized Randomness?!

I'd say this query is mostly semantic. The OP states "Let's say there are two parallel universes, exactly alike," just what does this mean? It could mean they are now and will be always identical in all respects. Then the RNGs must produce the same sequence. It could mean by observation th...
Sun Jun 08, 2008 2:24 am UTC
Forum: Logic Puzzles
Topic: Avoiding the Librarian's attention
Replies: 18
Views: 3480

### Re: Avoiding the Librarian's attention

Following ++\$_'s hide in plain sight rationale, the rightmost two stations in any row will be given less attention than the others. I'd favor m or n since only one of the two "T" locations has a good view of their screens; e is more obviously hidden.
Sun Jun 08, 2008 2:07 am UTC
Forum: Logic Puzzles
Topic: Keyboard puzzle
Replies: 53
Views: 14928

### Re:

The Sherlock thing is from Conan Doyle's "The Adventure of the Dancing Men," in which Holmes uses frequency analysis (counting of the frequency of symbols in a cipher and comparing it to that of the cleartext's language) to break a doodle-based cipher. Frequency analysis is one of the eas...
Sun Jun 08, 2008 1:05 am UTC
Forum: Logic Puzzles
Topic: 1800s Era Defense/Assault Puzzle
Replies: 29
Views: 3940

### Re: 1800s Era Defense/Assault Puzzle

The clarification on "Is lots and lots of ammo infinite?" wouldn't allow killing a half million people before being reduced to "primitive" weapons. That leaves an awful lot of people.
Thu Jun 05, 2008 8:20 pm UTC
Forum: Science
Topic: How many ways can you empty a glass of water?
Replies: 129
Views: 12904

### Re: How many ways can you empty a glass of water?

I don't recall seeing this suggestion:
use glass for artillery practice.
Thu Jun 05, 2008 8:02 pm UTC
Forum: General
Topic: Real Life Weapon Choices (olden like the plague)
Replies: 190
Views: 87585

### Re: real life weapon choices (olden days)

Looooong ago I read a lot of history and historical fiction relating to Greek and Roman warfare. My recollection is that war elephants gained their reputation when first used against Alexander's forces; the Macedonian cavalry mounts shied and baulked at the unfamiliar scent. Once acclimated, however...
Tue Jun 03, 2008 4:29 am UTC
Forum: Mathematics
Topic: A most mysterious of numbers
Replies: 33
Views: 5679

### Re: A most mysterious of numbers

See the notes at http://aleph0.clarku.edu/~djoyce/java/elements/bookI/propI47.html.

According to this Proclus does not attribute the theorem to Euclid (indeed he refers to it as the Theorem of Pythagoras), but rather the particular proof presented.
Mon Jun 02, 2008 9:35 pm UTC
Forum: Science
Topic: How many ways can you empty a glass of water?
Replies: 129
Views: 12904

### Re: How many ways can you empty a glass of water?

The thermodynamic technique : The liquid-vapor interface at the water surface is defined by a statistically maintained balance. There is thus a non-vanishing chance for the interface to drop to the bottom of the glass (ie for the glass to be empty). Wait. The main problem with this approach is that ...
Mon Jun 02, 2008 7:19 pm UTC
Forum: Mathematics
Topic: A most mysterious of numbers
Replies: 33
Views: 5679

### Re: A most mysterious of numbers

This is a footnote to Fafnir43 's comment on Fermat's last theorem. In addition to numerous citations of results Fermat said he had proven, there are several results he states he believes to be true was had been unable to prove. This does lend credence to the idea that he had a proof, although most ...
Mon Jun 02, 2008 3:23 pm UTC
Forum: Logic Puzzles
Topic: 1800s Era Defense/Assault Puzzle
Replies: 29
Views: 3940

### Re: 1800s Era Defense/Assault Puzzle

Wikipedia (at http://en.wikipedia.org/wiki/World_population ) gives estimates of slightly under 10 9 to 1.6*10 9 as the world population during the 19th century. Using an average kill rate of 1/sec, it would require 31.6 years to kill 10 9 (UK one thousand million, US 1 billion) people. This allows ...
Mon Jun 02, 2008 3:07 pm UTC
Forum: Mathematics
Topic: A most mysterious of numbers
Replies: 33
Views: 5679

### Re: A most mysterious of numbers

hyperion wrote:
BeetlesBane wrote:Well, the Pythagorean theorem is nanmed for a man who is purported to have attempted to hide the knowledge.

How the bloody hell does that work?
In before "a2 + b2 = c2 lolololol"

Not very well.
Mon Jun 02, 2008 2:13 pm UTC
Forum: Mathematics
Topic: A most mysterious of numbers
Replies: 33
Views: 5679

### Re: A most mysterious of numbers

Well, the Pythagorean theorem is nanmed for a man who is purported to have attempted to hide the knowledge.
Mon Jun 02, 2008 7:49 am UTC
Forum: Logic Puzzles
Topic: 1800s Era Defense/Assault Puzzle
Replies: 29
Views: 3940

### Re: 1800s Era Defense/Assault Puzzle

Mr. Beck wrote:Bored soldiers with a cannon =/= the entire world trying to destroy something.

Agreed. But it does offer a feel for the limits of early 19th century firepower.
Mon Jun 02, 2008 4:12 am UTC
Forum: Mathematics
Topic: poor e
Replies: 40
Views: 5263

### Re: poor e

antonfire,
Given the way you have worded your previous comment and some comments you have made in another thread, I am left with the impression you wish to engage me in a flame war. I do not wish to comply.
Mon Jun 02, 2008 12:06 am UTC
Forum: Mathematics
Topic: Orbit Stability
Replies: 26
Views: 3010

### Re: Orbit Stability

antonfire , the Heisenberg principle does not (repeat NOT) prohibit anything from having a position and a momentum at the same time. what it does do it place a limit on the combined (as product) accuracy to which those two (vector) quantities can be measured at the same time. So the argument implie...
Sun Jun 01, 2008 8:24 pm UTC
Forum: Logic Puzzles
Topic: 1800s Era Defense/Assault Puzzle
Replies: 29
Views: 3940

### Re: 1800s Era Defense/Assault Puzzle

daryuu wrote:Did they not have enough firepower to destroy a pyramid? I don't know how much it would take, but if the entire world's supply of explosives couldn't do it I would be fairly surprised...

Napoleon didn't have sufficient firepower to destroy the Sphynx.
Sun Jun 01, 2008 4:45 pm UTC
Forum: Language/Linguistics
Topic: Punnilingus
Replies: 135
Views: 67734

### Re: Punnilingus

A joke you need to have explained never seems funny.
Sun Jun 01, 2008 7:05 am UTC
Forum: Mathematics
Topic: poor e
Replies: 40
Views: 5263

### Re: poor e

The appearance of pi in weird places becomes less mystifying when you realize it's mostly because so many definite integrals evaluate to something with pi in them. Connections to area/volume with pi shouldn't be surprising. And of course e^x is likely to appear anytime you have differential equatio...
Sun Jun 01, 2008 3:23 am UTC
Forum: Mathematics
Topic: Breast Speed/Bounce equation (Not a joke)
Replies: 27
Views: 7686

### Re: Breast Speed/Bounce equation (Not a joke)

Hm... the function in question would satisfy the differential equation for damped harmonic motion, wouldn't it? possibly, but we have a more complex problem here. How do we model the macro-vibrations of a homogeneous 3 dimensional spheroid attached to a rigid anchor? Actually it gets worse. The bre...
Sun Jun 01, 2008 2:38 am UTC
Forum: General
Topic: Who the dickens are you?
Replies: 10922
Views: 2378079

### Re: INTRO THREAD THE THIRD

Rustrum,
Try writing a novel as a collection of stand alone vignettes. If you bog down halfway through, you'll at least have some finished short stories.
Sun Jun 01, 2008 2:29 am UTC
Forum: Language/Linguistics
Topic: Punnilingus
Replies: 135
Views: 67734

### Re: Punnilingus

A termite walks into a bar and asks, "Where is the bar tender?" I... I don't get that one. :oops: Is it that "tender" means soft here? If it is, it's not that funny, but I doubt that's what it is. Yeah, "tender" can be soft, but it said "where is the bar tender&qu...
Sat May 31, 2008 5:14 am UTC
Forum: Mathematics
Topic: Why can I not figure out this (is it calculus?) problem
Replies: 5
Views: 1586

### Re: Why can I not figure out this (is it calculus?) problem

To approach solving for y as a "function" of x (as mentioned it won't really be a function), suppose I asked you what the value of y would be if x were set to 0 - could you answer that? If so how? Now what if I were to set x to 2, or 10, or -3... Now try to find y for whatever value I migh...
Sat May 31, 2008 3:42 am UTC
Forum: Mathematics
Topic: Doing original work in mathematics
Replies: 8
Views: 2048

### Re: Doing original work in mathematics

Also check areas that supposed to be worn out. Newer tools and techniques may open up new questions or ideas. For instance, most of the starting equations in chaos theory had been completely studied around 1900; techniques for computer graphical representation developed after 1960 offered new insigh...
Sat May 31, 2008 3:15 am UTC
Forum: Mathematics
Topic: Majoring in Mathematics
Replies: 8
Views: 1891

### Re: Majoring in Mathematics

Carefully go through any of the multi-page threads in this forum. The discussions, especially the OT discussions, should serve as a good guide.
Sat May 31, 2008 2:55 am UTC
Forum: Mathematics
Topic: A most mysterious of numbers
Replies: 33
Views: 5679

### Re: A most mysterious of numbers

Beacons! wrote:In other modes it seems to reach its limit (at least to 8 digits) much faster than in radians. How odd.

This observation is made using decimal representation; would we get the result in hexadecimal...
Sat May 31, 2008 2:46 am UTC
Forum: Mathematics
Topic: Orbit Stability
Replies: 26
Views: 3010

### Re: Orbit Stability

(After quoting BeetlesBane): last time i looked physics had progressed somewhat since newton. you can indeed have particles with no mass (0 rest mass) but with momentum, and they are effected by gravity. a photon is a perfect example of this. however i'm also willing to believe the massless part co...
Sat May 31, 2008 2:36 am UTC
Forum: Mathematics
Topic: poor e
Replies: 40
Views: 5263

### Re: poor e

Cosmologicon , You say "I know nobody said otherwise, but it seems clear to me that knowing whether your problem has anything to do with circles doesn't really tell you whether or not your solution has anything to do with pi." Implicitly that's what Turambar 's statement "Pi is only ...
Fri May 30, 2008 5:08 am UTC
Forum: Mathematics
Topic: Spin in R4
Replies: 5
Views: 1387

### Re: Spin in R4

I encountered something similar in a general relativity seminar - the Weyl solution of the cosmological equation (I'm sure it was Weyl's soluion but I may be citing the wrong equation). Unfortunately, general relativity is handled entirely in tensor notation.
Fri May 30, 2008 4:50 am UTC
Forum: Mathematics
Topic: poor e
Replies: 40
Views: 5263

### Re: poor e

But the resultant differential equation has a two-dimensional solution, height as a function of time. The simple pendulum, also a harmonic oscillator, uses an angle as its obvious measurement.
Fri May 30, 2008 4:36 am UTC
Forum: Mathematics
Topic: Orbit Stability
Replies: 26
Views: 3010

### Re: Orbit Stability

The last time I looked at Newton's third law, the only effect any force field can have on a particle is to change its momentum in proportion to the force. If the particle has 0 mass, its momentum is also 0 and can only be changed by creating some mass. That Dynotech referred to the 3rd particle as m...
Fri May 30, 2008 4:27 am UTC
Forum: Mathematics
Topic: poor e
Replies: 40
Views: 5263

### Re: poor e

Radian measurement of angles arises anytime calculus is invoked. Just as base e is natural for logs and exponentials in calculus, radians (defined by measuring the arc length along the circumference of a circle in terms of its radius) are the "natural" angle measurement. NB: Cosmologician ...
Fri May 30, 2008 4:16 am UTC
Forum: Mathematics
Topic: A most mysterious of numbers
Replies: 33
Views: 5679

### Re: A most mysterious of numbers

Actually there are different answers depending on which units your calculator assumes angles are given in. ie: 90 deg = pi/2 rad = 100 grad, and no doubt equal other values in systems I'm not familiar with, but they all have the same cosine. Thus solving for x=cos(x) will depend on what units you pi...
Fri May 30, 2008 4:04 am UTC
Forum: Mathematics
Topic: poor e
Replies: 40
Views: 5263

### Re: poor e

Of course when pi seems to appear without involving a circle, there is usually a hidden circle present. Thus Buffon's Needle Problem ( http://www.angelfire.com/wa/hurben/buff.html ) evaluates pi, seemingly without recourse to a circle. But the calculation requires considering all orientations of the...
Fri May 30, 2008 3:49 am UTC
Forum: Mathematics
Topic: Orbit Stability
Replies: 26
Views: 3010

### Re: Orbit Stability

This isn't Euler's simplification of the three-body problem since as given the 3rd particle has no mass. Thus this particle is not effected by the gravitational field of the initial particles.
Thu May 29, 2008 6:56 pm UTC
Forum: Mathematics
Topic: A Matter of Steam-Powered Math
Replies: 29
Views: 3128

### Re: A Matter of Steam-Powered Math

I'm wondering if what could be called a "Schwarzchild mass" (ie: a mass concentrated within a sphere having its Schwarzchild radius) might serve in place of a point mass. The radius would be insignificant in most classical scales, allowing the mass to be treated as concentrated at a point....