Search found 78 matches

by davetp425
Fri Jul 02, 2010 2:24 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0761: "DFS"
Replies: 77
Views: 19915

Re: "DFS" Discussion

This is why I like to open links in a new tab: they appear at the end of the list of tabs, so if I process tabs left-to-right then I've got a queue, which gives breadth-first search. The fact that 'no one talks like this in real life' is simply a literary mechanism - if you have read comic books, do...
by davetp425
Sat May 15, 2010 8:57 pm UTC
Forum: Computer Science
Topic: flow chart markup language
Replies: 10
Views: 23157

Re: flow chart markup language

Awesome, that sounds like exactly what I wanted; I'll look into that. Thanks! EDIT: Oh wait, did you say it only works on acyclic graphs? A graph where edges are theorems showing which statements imply each other would probably have a lot of islands of statements that all imply each other. Would thi...
by davetp425
Fri May 14, 2010 8:15 pm UTC
Forum: Computer Science
Topic: flow chart markup language
Replies: 10
Views: 23157

flow chart markup language

I'm studying for my linear algebra final, and drawing the directed graph of which statements imply other statements. It would be pretty cool if I could just enter theorems in some Prolog-like language and get a nicely formatted flow chart without having to worry about specific formatting. Does such ...
by davetp425
Tue Dec 15, 2009 7:52 am UTC
Forum: Language/Linguistics
Topic: Lojban rule for pronouncing decimals
Replies: 1
Views: 897

Lojban rule for pronouncing decimals

I was reading the Lojban Reference Grammar section about numbers and math. I don't get this example: 3.10) pi pa ki'o pa re ki'o pa point one comma one two comma one .101 012 001 http://www.lojban.org/publications/reference_grammar/chapter18.html#e3d10 I think this is a typo, and it should read: 3.1...
by davetp425
Mon Dec 14, 2009 5:00 am UTC
Forum: Science
Topic: Shouldn't the Universe... not exist?
Replies: 30
Views: 3416

Re: Shouldn't the Universe... not exist?

Isn't the following a problem with the idea that time extends infinitely far into the past?: Entropy increases with time, so after infinite time entropy must tend toward its maximum. If the universe has existed for an infinitely long time, it should be in the maximum possible entropic state already....
by davetp425
Sat Dec 12, 2009 5:34 am UTC
Forum: Science
Topic: Shouldn't the Universe... not exist?
Replies: 30
Views: 3416

Re: Shouldn't the Universe... not exist?

Assumption: Everything has a cause. It follows that these causes must themselves has a cause. Then, there must be an original cause. However, there would be nothing to cause this original cause. Therefore, nothing should exist. (emphasis mine) Does that really follow? This seems like the following ...
by davetp425
Sun Nov 29, 2009 9:24 pm UTC
Forum: Science
Topic: backyard electroplating: viability and safety (and legality)
Replies: 4
Views: 1060

Re: backyard electroplating: viability and safety (and legality)

Ok, Cu won't dissolve naturally into HCl, but I can still drive it into solution with a current, right? Just strip the copper of its electrons and pump them into the other side of the solution. Then H 2 will be released where the electrons re-enter the solution and the copper will be ionized and dis...
by davetp425
Sun Nov 29, 2009 3:22 am UTC
Forum: Science
Topic: backyard electroplating: viability and safety (and legality)
Replies: 4
Views: 1060

backyard electroplating: viability and safety (and legality)

I did a fun chemistry lab recently where we copper plated things; I want to try something similar on my own. I need cheap and easy access to some chemicals, so I was thinking something like this: ⋅ Get copper (wire, plates, whatever's cheapest by mass) and cheap HCl (muriatic acid) at hard...
by davetp425
Mon Nov 16, 2009 3:35 am UTC
Forum: Religious Wars
Topic: Mouse vs Keyboard
Replies: 69
Views: 64171

Mouse vs Keyboard

I did a quick search and, shockingly, didn't find anything for this topic. Keyboard vs Mouse Are keyboard shortcuts faster than onscreen buttons? I thought the keyboard was faster (and we all know it's definitely way cooler) but I just read that Apple's research found that keyboard users only feel m...
by davetp425
Mon Nov 09, 2009 9:46 pm UTC
Forum: School
Topic: foreign language for an engineer? which, and how?
Replies: 18
Views: 2856

foreign language for an engineer? which, and how?

I'm a freshman in college thinking of a career in engineering, or something technical like computers or physics. ABET accreditation is pretty strict though, so I don't know how I'm going to be able to take classes in my other interests or try out new things. I'd like to learn a foreign language, but...
by davetp425
Tue Oct 20, 2009 3:53 am UTC
Forum: Science
Topic: Charged Ice Coil Gun
Replies: 31
Views: 2745

Re: Charged Ice Coil Gun

So I'm just remembering that I posted this almost a year ago and kind of abandoned it... but I wanted to clarify what I meant: You have a tub of NaCl(aq), which is really Na+(aq) and Cl-(aq) because NaCl is an electrolyte. If you apply an electric field to the tub somehow... Will the concentration o...
by davetp425
Tue Oct 13, 2009 5:44 am UTC
Forum: Forum Games
Topic: Random bitstream! (000zerozero000000zero)
Replies: 1947
Views: 237443

Re: Random bitstream! (000zerozero000000zero)

1
by davetp425
Tue Oct 06, 2009 1:54 pm UTC
Forum: Coding
Topic: What's a good first programming language, without install?
Replies: 32
Views: 2950

Re: What's a good first programming language, without install?

I would recommend ruby along with Why's Poignant Guide(you'll have to search hard for a archive of it though) or maybe C/++ if you feel like being "rough" ¡This cheese is burning me! also you could buy her a TI-83+ and teach her TI-Basic.. a little annoying to use though ¡This cheese is b...
by davetp425
Sun Oct 04, 2009 10:22 pm UTC
Forum: Coding
Topic: What's a good first programming language, without install?
Replies: 32
Views: 2950

Re: What's a good first programming language, without install?

Berengal wrote:Internet to the rescue!

http://codepad.org/NcDZl42W


Perfect! This looks like a great demo. I can use this to convince her to get IDLE.
by davetp425
Sun Oct 04, 2009 9:07 pm UTC
Forum: Coding
Topic: What's a good first programming language, without install?
Replies: 32
Views: 2950

What's a good first programming language, without install?

My girlfriend is curious about what programming is like, since I've talking about this fun Scheme class I'm in. I was going to teach her some Scheme or learn Python with her but she doesn't want to install anything since her laptop is so terrible. Does anyone have any ideas for a good first programm...
by davetp425
Wed Jul 08, 2009 11:03 pm UTC
Forum: Mathematics
Topic: verifying accuracy of a probability?
Replies: 7
Views: 936

verifying accuracy of a probability?

Suppose I say: "There is a 93.7% chance of rain for a <a particular place> tomorrow." How can I say it's really 93.7; whether or not it actually rains tomorrow, I can still claim my prediction was right. If it rains, then I predicted it, and if it doesn't, I can claim that that was the 6.2...
by davetp425
Tue May 12, 2009 4:00 am UTC
Forum: Science
Topic: Why isn't EMP lethal?
Replies: 16
Views: 3938

Re: Why isn't EMP lethal?

Neurons actually work through chain chemical reactions. My impression is that the signal travels between neurons chemically, but within neurons electrically. I thought an EMP could induce current in each individual neuron. The explanation about loop of wire vs sac of brine makes sense to me. The sa...
by davetp425
Mon May 11, 2009 3:36 am UTC
Forum: Science
Topic: Why isn't EMP lethal?
Replies: 16
Views: 3938

Why isn't EMP lethal?

EMP induces current in any conductor, right? Neurons have an electrical signal in them (even though the signal goes back and forth between chemical and electrical), so they must conduct, right?

Why doesn't an EMP induce deadly amounts of current in humans' or animals' nervous systems?
by davetp425
Thu Mar 05, 2009 12:06 am UTC
Forum: Science
Topic: Lindt truffles taste cold - why?
Replies: 12
Views: 14289

Re: Lindt truffles taste cold - why?

Fats aren't usually good conductors of heat--the heat absorbed by the truffle when it melts is probably much more important. The truffle would taste colder than the chocolate shell because it melts faster; chocolate melts at a temperature not much lower than that of the mouth, while the truffle has...
by davetp425
Thu Mar 05, 2009 12:03 am UTC
Forum: Coding
Topic: Homework Help??
Replies: 21
Views: 1517

Re: Homework Help??

What are some examples of languages in which a loop is faster than the equivalent recursion, and some in which the recursion is just as fast as a loop?
by davetp425
Wed Mar 04, 2009 3:34 am UTC
Forum: Coding
Topic: Homework Help??
Replies: 21
Views: 1517

Re: Homework Help??

I believe it's n(n+1)/2, so

(5)(5+1)/2 = 15 checks
by davetp425
Mon Mar 02, 2009 9:39 pm UTC
Forum: Science
Topic: Lindt truffles taste cold - why?
Replies: 12
Views: 14289

Lindt truffles taste cold - why?

I'm eating a Lindt ball right now, the kind with a chocolate shell and this truffle inside that melts very easily. The truffle part always feels very cool (as in cold). Is this because it's absorbing heat to melt?
by davetp425
Sat Feb 28, 2009 2:52 am UTC
Forum: Mathematics
Topic: AMS "Who wants to be a mathematician?" Competition
Replies: 1
Views: 609

AMS "Who wants to be a mathematician?" Competition

I just took this 10 minute timed, 10 question* test to see if I can compete in this contest: "Who wants to be a mathematician?" which is run by the AMS. Has anyone else heard of this? After taking this little test and watching videos of the actual competition online, I'm surprised how easy...
by davetp425
Wed Jan 21, 2009 7:53 pm UTC
Forum: Science
Topic: matter/antimatter imbalance - caused by Hawking radiation?
Replies: 12
Views: 1714

Re: matter/antimatter imbalance - caused by Hawking radiation?

Oh, I wasn't asking if there is any antimatter out there, just if there's a space to put it without it annihilating. In case we ever try to built an anti-black hole to see if it has hair. :P
by davetp425
Wed Jan 21, 2009 7:31 pm UTC
Forum: Science
Topic: matter/antimatter imbalance - caused by Hawking radiation?
Replies: 12
Views: 1714

Re: matter/antimatter imbalance - caused by Hawking radiation?

Also, in order for this process to explain asymmetry, you need to explain why antimatter would form more black holes than normal matter does. Well, if black holes were the unbalancing mechanism I'd say that it's just a coincidence: the random distribution of matter right after the Bang happened to ...
by davetp425
Wed Jan 21, 2009 5:51 am UTC
Forum: Science
Topic: matter/antimatter imbalance - caused by Hawking radiation?
Replies: 12
Views: 1714

matter/antimatter imbalance - caused by Hawking radiation?

If I have a star made of regular old matter, and it collapses into a black hole, and then over an incredibly long period of time evaporates due to Hawking radiation, have I just converted matter to radiation without involving antimatter? Similarly, if I have an amount of antimatter, can I convert it...
by davetp425
Mon Dec 22, 2008 3:48 am UTC
Forum: Science
Topic: Samurai Energy Transfer
Replies: 11
Views: 2223

Re: Samurai Energy Transfer

Very interesting. Do you ever distract yourself by trying to think about what's happening from a scientific standpoint? Is it better to just forget the mechanics and try to imagine things like chi, or can thinking about biomechanics cooperate with imaginig chi and energy?
by davetp425
Mon Dec 22, 2008 2:57 am UTC
Forum: Science
Topic: Samurai Energy Transfer
Replies: 11
Views: 2223

Re: Samurai Energy Transfer

Is this an actual samurai technique? If it is, I expect it to have something to do with the samurai's motion and stance, but does anyone know what?
by davetp425
Mon Dec 22, 2008 1:47 am UTC
Forum: Science
Topic: Samurai Energy Transfer
Replies: 11
Views: 2223

Samurai Energy Transfer

I just saw the Time Warp episode on samurai, and I'm wondering what that "energy transfer" thing they were talking about is all about. About halfway through this video http://www.youtube.com/watch?v=ZtT03lzCuvA the samurai can throw this guy to the ground with a very relaxed push to the he...
by davetp425
Sat Dec 20, 2008 9:58 pm UTC
Forum: Science
Topic: Space question
Replies: 14
Views: 2098

Re: Space question

Are you trying to build Dyno-Capsules? :D
by davetp425
Sat Dec 20, 2008 7:03 pm UTC
Forum: Science
Topic: Space Lightning
Replies: 28
Views: 2773

Re: Space Lightning

Wow. Any time you start measuring electrons in kilograms... that's... wow. I'm speechless.

This would mean that a lightning bolt would have a non-negligible mass of electrons moving through it, and therefore a non-negligible momentum. (right?) That's just ridiculous. Wow.
by davetp425
Tue Dec 16, 2008 3:09 am UTC
Forum: Science
Topic: Charged Ice Coil Gun
Replies: 31
Views: 2745

Re: Charged Ice Coil Gun

Maybe he just meant "stick it in a big electric field so that some of the Na separate from the Cl. Yeah, pretty much. My understanding is that since NaCl is a strong electrolyte, the vast majority of the Na+ separate from the Cl- when you dissolve them. And I thought to polarize a solution wou...
by davetp425
Mon Dec 15, 2008 3:36 am UTC
Forum: Science
Topic: Charged Ice Coil Gun
Replies: 31
Views: 2745

Charged Ice Coil Gun

Is this possible (despite it being completely impractical): Take a volume of water with salt dissolved in it. Polarize it, EDIT: apply an electric field to it so that the Na+ ions drift to one end and the Cl- ions drift to the other, then divide it in half to have two charged volumes of liquid. Each...
by davetp425
Mon Dec 15, 2008 1:00 am UTC
Forum: Science
Topic: Space Lightning
Replies: 28
Views: 2773

Re: Space Lightning

Cool. Is the vacuum in your mass spectrometer comparable to the vacuum between the earth and moon? (Are the densities on the same order of magnitdude?) Can anyone do the calculation on the earth-moon system's capacitace? Then from there we can find things like how much voltage you need to charge it ...
by davetp425
Sun Dec 14, 2008 2:52 am UTC
Forum: Science
Topic: Space Lightning
Replies: 28
Views: 2773

Re: Space Lightning

Electricity can't strike across vacuum. There's nothing to conduct it. It's much easier for electricity to flow through a conductor because the electrons don't want to climb out of the potential well around the nucleus, but once they've been given enough energy to escape they can fly around just li...
by davetp425
Sun Dec 14, 2008 12:05 am UTC
Forum: Science
Topic: Space Lightning
Replies: 28
Views: 2773

Space Lightning

We just started capacitance in my high school physics class. One thing mentioned was that lightning occurs because the clouds and the ground act as a capacitor: charge difference builds up, and when the voltage is too strong it discharges. Then for some reason I pictured this happening between the e...
by davetp425
Mon Nov 10, 2008 4:38 am UTC
Forum: Mathematics
Topic: Rubik's Cube patterns
Replies: 4
Views: 1194

Rubik's Cube patterns

I recently started playing with a Rubik's Cube again, and finally learned the formulas to solve the last layer, so I started solving for configurations other than the "solved" 6 solid faces. I thought any configuration was possible (without removing stickers) but now I've realized that som...
by davetp425
Sun Nov 09, 2008 2:01 am UTC
Forum: Mathematics
Topic: irrational numbers as typewriting monkeys
Replies: 41
Views: 4585

Re: irrational numbers as typewriting monkeys

Haha, I can't believe this only occurred to me just now:

The phrase "helpimtrappedinauniversefactory" will have a very high compression rate when converted to its index in pi. http://xkcd.com/10/ :lol:
by davetp425
Tue Oct 28, 2008 3:11 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0344: "1337: Part 4"
Replies: 118
Views: 23161

Re: "1337: Part 4" Discussion

I want to know haw the Mafiaa ninjas hid katanas in their briefcases. Yes! How do they do it? Are the swords collapsible? A hinge where the hilt meets the blade might affect its performance relatively little, but would only reduce the length by the length of the hilt. A hinge on the blade itself wo...
by davetp425
Tue Oct 21, 2008 4:13 am UTC
Forum: Science
Topic: Muscles, torque and work
Replies: 12
Views: 1682

Re: Muscles, torque and work

Muscles' energy loss comes from relaxing, not contracting? But they also require energy to maintain a position against force. When doing leg lifts, say, do you spend more energy by cheating and resting for a second than you would by keeping the same position?

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