## Search found 264 matches

- Fri Mar 17, 2017 2:34 am UTC
- Forum: Mathematics
- Topic: Elementary probability
- Replies:
**5** - Views:
**401**

### Re: Elementary probability

That depends what you mean by "reasonably certain". First, a simpler question: how many letters would you have to send out to expect 100 replies on average? Second, in that scenario, what's the chance of getting less than 100? And how many responses are you "reasonably certain" y...

### Re: Free Will

I dont mean to draw a comparison between "free will" and randomness. Only that there certainly cant be free will in a deterministic, non-random universe. Why not, though? If by "free will" you mean that something outside causality should reach in, override your history/knowledge...

- Mon Feb 27, 2017 6:00 am UTC
- Forum: Mathematics
- Topic: WoW: A Strange Game. The only way to win is not to play.
- Replies:
**7** - Views:
**646**

### Re: WoW: A Strange Game. The only way to win is not to play.

I think that would have limited success in the general case. Some builds have strategies that very quickly go from optimal to terrible if you deviate slightly, and I think evolutionary algorithms are bad at finding such optima? I have only the most pop-sci-level understanding of evolutionary algorit...

- Sun Feb 26, 2017 9:33 pm UTC
- Forum: Mathematics
- Topic: WoW: A Strange Game. The only way to win is not to play.
- Replies:
**7** - Views:
**646**

### Re: WoW: A Strange Game. The only way to win is not to play.

Priority lists are usually arrived at by taking a few initial guesses, and simming a lot of permutations. I suppose you could try to automatically generate all possible permutations, but this sounds inefficient.

- Sat Feb 11, 2017 7:48 pm UTC
- Forum: Mathematics
- Topic: "There is an Exception to every rule"
- Replies:
**32** - Views:
**2962**

### Re: "There is an Exception to every rule"

The difference being a multiple of p would be denoted p|(a^p-a), though.

- Sun Oct 09, 2016 6:19 pm UTC
- Forum: Science
- Topic: Question about the law of entropy
- Replies:
**4** - Views:
**916**

### Re: Question about the law of entropy

No, since every process by which we might do that obeys the laws of thermodynamics. Computers don't get a free pass.

It's possible to imagine futures which are actually lower-entropy than the current universe. Such futures are impossible.

It's possible to imagine futures which are actually lower-entropy than the current universe. Such futures are impossible.

- Tue Sep 06, 2016 7:21 am UTC
- Forum: Science
- Topic: Science-based what-if questions
- Replies:
**233** - Views:
**10135**

### Re: 2600 km in 1/30 second.

What is it that we're moving? A single electron won't do much of anything interesting, but something person-sized or larger... I imagine it would look something like a 2600km line charge made out of nukes, with an especially large nuke at the end when all of that kinetic energy discharges into the s...

- Thu Aug 11, 2016 6:40 pm UTC
- Forum: Mathematics
- Topic: N digit sequence within π
- Replies:
**12** - Views:
**1466**

### Re: N digit sequence within π

At the very least the normality of π is unknown. If true, it would entail that any finite sequence of n digits in base b has a probability b^-n of occurring at every place in the number, which would entail that a chosen sequence occurs at least once almost surely somewhere in π. I'm not sure in wha...

- Wed Aug 03, 2016 4:35 pm UTC
- Forum: Science
- Topic: sound earthquake
- Replies:
**7** - Views:
**1283**

### Re: sound earthquake

I don't think it is possible to create a sound wave in air strong enough to cause a magnitude 4 earthquake (smaller than 4 doesn't count in my mind) when transferred into the ground. The maximum intensity sound in air at standard pressure isn't very high. But you could presumably create the sound i...

- Fri Jul 22, 2016 5:55 am UTC
- Forum: Mathematics
- Topic: The liar paradox as a basis for kantian metaphysics
- Replies:
**11** - Views:
**2096**

### Re: The liar paradox as a basis for kantian metaphysics

That's still self-reference, you've just hidden it better.

Sentence A says "B is false". But that just means ""C is false" is false", which in turn is """A is false" is false" is false".

Sentence A says "B is false". But that just means ""C is false" is false", which in turn is """A is false" is false" is false".

- Mon Jul 11, 2016 2:17 am UTC
- Forum: Mathematics
- Topic: Trisecting an angle
- Replies:
**63** - Views:
**7362**

### Re: Trisecting an angle

I'm not sure I understand the distinction you're making? If I had a way to construct an angle that happens to be 1/3 of another angle, for any other angle, then surely I can trisect any angle I want. It's precisely the fact that this can't be done for some angles (using the standard tools) which lea...

- Mon Jun 13, 2016 12:50 pm UTC
- Forum: Mathematics
- Topic: Completions, Cauchy sequences, and countability
- Replies:
**7** - Views:
**2184**

### Re: Completions, Cauchy sequences, and countability

Maybe I'm misinterpreting your dissatisfaction, but isn't Cantor's theorem also a diagonalisation argument? Huh, you're right! I hadn't thought of it that way before. Diagonalization on decimal representations feels kind of hacked together, because you need to invoke the additional fact that decima...

- Mon Jun 13, 2016 5:57 am UTC
- Forum: Mathematics
- Topic: Completions, Cauchy sequences, and countability
- Replies:
**7** - Views:
**2184**

### Completions, Cauchy sequences, and countability

The most commonly presented proof the uncountability of the reals is the diagonalization argument, using decimal representations. While clearly valid, this has never been particularly satisfying to me. Perhaps I am unfairly biased against decimal representations. Recently, studying the p-adics has i...

- Wed Jun 08, 2016 3:57 am UTC
- Forum: Mathematics
- Topic: Math: Fleeting Thoughts
- Replies:
**377** - Views:
**88306**

### Re: Math: Fleeting Thoughts

I don't know if this is the original etymology, but for example sqrt(6) is a root of the polynomial x^2 - 6.

- Wed Jun 08, 2016 3:11 am UTC
- Forum: Mathematics
- Topic: Math: Fleeting Thoughts
- Replies:
**377** - Views:
**88306**

### Re: Math: Fleeting Thoughts

Oh, so it's an extended meaning of the term "root"! Thank you, that makes sense now.

- Tue Jun 07, 2016 8:33 pm UTC
- Forum: Mathematics
- Topic: Math: Fleeting Thoughts
- Replies:
**377** - Views:
**88306**

### Re: Math: Fleeting Thoughts

Another dumb question: I'm struggling to parse this sentence. "A polynomial with integer coefficients has a root in Z_p if and only if it has an integer root modulo p^k for any k >= 1". I get what it means to say two numbers are congruent mod n; it's a relationship between two numbers. I'm...

- Tue May 31, 2016 10:16 pm UTC
- Forum: Mathematics
- Topic: Math: Fleeting Thoughts
- Replies:
**377** - Views:
**88306**

### Re: Math: Fleeting Thoughts

Oh, duh. Thank you.

- Tue May 31, 2016 9:29 pm UTC
- Forum: Mathematics
- Topic: Math: Fleeting Thoughts
- Replies:
**377** - Views:
**88306**

### Re: Math: Fleeting Thoughts

Is it valid to say that a set which is not open must be closed? Or is there some third possibility?

- Sun May 29, 2016 4:18 pm UTC
- Forum: Mathematics
- Topic: Misunderstanding basic math concepts, help please?
- Replies:
**319** - Views:
**29070**

### Re: Misunderstanding basic math concepts, help please?

I specify a particular excluded middle system X to 'describe' all z. X -> 'describe' all z. Since I want X to be 'describable' then I think the following are valid deductions: 1. X must be a member of z. 2. All 'describe' are members of z. 3. All z are 'described' within X. 4. not-z cannot be 'desc...

- Wed May 25, 2016 9:37 pm UTC
- Forum: Mathematics
- Topic: Misunderstanding basic math concepts, help please?
- Replies:
**319** - Views:
**29070**

### Re: Misunderstanding basic math concepts, help please?

The first thing to note about divided middle propositions is that they don't have a middle bit. For every mathematical proposition* there is no semi-x. The law of the excluded middle is about truth values, not propositions. For any proposition x, either x is true or !x is true, but never both. For ...

- Thu May 19, 2016 5:50 pm UTC
- Forum: Mathematics
- Topic: Meta-Probability Problem
- Replies:
**16** - Views:
**2613**

### Re: Meta-Probability Problem

You'd run into a bit of a technical problem, because normals are over the entire real line, while probabilities are restricted to [0,1]. You could use some kind of truncated re-scaled normal, though, or something that approximates that. Unlike the uniform, there's more than one possible (approximate...

- Sun May 15, 2016 3:37 am UTC
- Forum: Mathematics
- Topic: Meta-Probability Problem
- Replies:
**16** - Views:
**2613**

### Re: Meta-Probability Problem

Well one of the heads involved in the discussion claims that because every distribution has a "complementary distribution" (i.e. p <=> 1-p) then the averages of the infinite probabilities gives a uniform distribution. I'm skeptical because of the way infinities are handled. This seems lik...

- Sat May 14, 2016 6:06 am UTC
- Forum: Mathematics
- Topic: Meta-Probability Problem
- Replies:
**16** - Views:
**2613**

### Re: Meta-Probability Problem

This comes to the fuzzy edge of what we mean by "probability". Ostensibly, coin flips are still independent and identically distributed, we just know that the probability of heads p is larger than 0.5. The chance of a head and a tail is 2*p*(1-p), so we can immediately conclude that the ch...

- Thu Apr 28, 2016 2:11 am UTC
- Forum: Mathematics
- Topic: Misunderstanding basic math concepts, help please?
- Replies:
**319** - Views:
**29070**

### Re: Misunderstanding basic math concepts, help please?

Xanthir wrote:. Again, "axiomatic mathematics" is not itself a logical system.

Would it be reasonable to phrase this as "There are many distinct axiomatic mathematics"?

- Sun Mar 06, 2016 5:32 am UTC
- Forum: Serious Business
- Topic: Communication? I am reading it long already.
- Replies:
**6** - Views:
**2725**

### Re: Communication? I am reading it long already.

I've spent a lot of time working with kids. Enough to be thoroughly divested of the idea that important thoughts are always communicated formally and properly. By all means, if you feel that someone isn't meeting you halfway in the attempt to maintain communication, you are not obligated to continue...

- Wed Jan 13, 2016 1:02 am UTC
- Forum: Science
- Topic: The Argument from Contingency
- Replies:
**42** - Views:
**3242**

### Re: The Argument from Contingency

Plenty of religious traditions have an Ultimate Source of Stuff which is not a god. There's no reason to call your ultimate source of stuff "God" without additional justification, and doing so prematurely is a great way to get confused.

- Tue Jan 12, 2016 8:30 pm UTC
- Forum: Science
- Topic: The Argument from Contingency
- Replies:
**42** - Views:
**3242**

### Re: The Argument from Contingency

Yeah, but if most of your first-year science was spent on "The Science Of Star Wars", that would ALSO not be a good sign about the structure of the curriculum.

- Tue Jan 12, 2016 4:11 am UTC
- Forum: Logic Puzzles
- Topic: Cannot Solve This
- Replies:
**2** - Views:
**3689**

### Re: Cannot Solve This

To make sure I'm understanding you, this is just a fancy way of displaying four equations? A-B = 9 C-D = 14 A+C = 12 B+D = 2 Is that correct? Because if those are the four equations, then your title is accurate: this system indeed cannot be solved. The sum of the third and fourth equations states th...

- Wed Dec 30, 2015 6:38 am UTC
- Forum: Science
- Topic: Training in stronger gravity
- Replies:
**7** - Views:
**1647**

### Re: Training in stronger gravity

I'd expect higher gravity to be really bad on the joints, the backbone, circulatory system. And generally the same as obesity. Long-term high gravity, almost certainly. Short-term high gravity for training purposes might be useful, but that's slightly further up the tech tree than weight training e...

- Fri Nov 13, 2015 7:01 pm UTC
- Forum: Science
- Topic: Gravity-temperature musings by Toffo
- Replies:
**162** - Views:
**17041**

### Re: Gravity-temperature musings by Toffo

I'm not talking 'everyday language' - I'm talking science. I'm querying your claim that science doesn't include energy input in the form of heat as part of the energy of an object. You want to argue about science, while I want to ponder some interesting inanimate objects. Oh yes, I said "we ar...

- Sun Aug 23, 2015 11:09 pm UTC
- Forum: Science
- Topic: Doctor/Quack/Shill Vitamin D?
- Replies:
**14** - Views:
**2698**

### Re: Doctor/Quack/Shill Vitamin D?

Basing your medical advice on one new study is also super sketchy, even if the study is real. Individual studies are wrong about stuff all the time.

- Wed Aug 12, 2015 5:45 pm UTC
- Forum: Science
- Topic: Life in the universe reaching stability
- Replies:
**2** - Views:
**1282**

### Re: Life in the universe reaching stability

It sounds like you're describing the concept of a great filter.

- Sun Aug 09, 2015 2:15 am UTC
- Forum: Science
- Topic: Puzzling artifacts and reasonable reasoning
- Replies:
**79** - Views:
**11639**

### Re: Puzzling artifacts and reasonable reasoning

Cradarc wrote:Here's a question: Why should we care?

It probably doesn't help physicists much, unless it proves the existence of time travel. For archaeologists and historians, it might have enormous import, and completely restructure our understanding of the ancient world.

- Tue Mar 10, 2015 5:07 am UTC
- Forum: Fictional Science
- Topic: Maximum efficiency when doing work over a distance
- Replies:
**57** - Views:
**12792**

### Re: Maximum efficiency when doing work over a distance

Telekinesis is in fact impossible, so there's not much to worry about there. But if it were real, there'd be nothing conservation-violating about a telekinetic pushing a satellite into a different orbit, just as there's nothing conservation-violating about magnets pulling things around. Well, as lon...

- Fri Jan 09, 2015 7:56 pm UTC
- Forum: General
- Topic: saving the internet
- Replies:
**29** - Views:
**4394**

### Re: saving the internet

It doesn't charge at all. You just throw it away. See, first you save all of wikipedia. You read like 5%. Then you throw it away and buy another one. That falls under the "the makers need a stern talking to". And they should be fired. From a cannon. In the direction of the sun. But why wo...

- Sat Dec 27, 2014 6:50 pm UTC
- Forum: Science
- Topic: Evolution: Random or intentional?
- Replies:
**187** - Views:
**19180**

### Re: Evolution: Random or intentional?

I don't think I agree with the claim that intent is just a feedback process. Consider the blue-minimizing robot . Assigning intent to the robot, even a circuitous intent like "reduce the amount of blue perceived in my camera software", still fails to describe edge cases like the hologram p...

- Fri Oct 31, 2014 7:32 pm UTC
- Forum: General
- Topic: Fungibility of Children (Split from xkcds favorite charities)
- Replies:
**51** - Views:
**7204**

### Re: Fungibility of Children (Split from xkcds favorite chari

I kinda have to wonder whether Meteoric has ever watched a movie or read a book about heroes, because to me it's pretty clear that we as a society *don't* want heroes who impersonally calculate the final utility of every decision. People who do that are sociopaths, and we tend to view them as somew...

- Fri Oct 31, 2014 6:17 am UTC
- Forum: General
- Topic: Fungibility of Children (Split from xkcds favorite charities)
- Replies:
**51** - Views:
**7204**

### Re: xkcd fora's favorite charities

A trolley car is hurtling down the tracks... Let's switch that around. The switch is old and rusty. It might not work at all, and it might derail the train killing the passengers on it. You don't know if there are any passengers on it. Also, the donkey and the sickly Burmese children are kind of fa...

- Fri Oct 10, 2014 6:44 am UTC
- Forum: Science
- Topic: Let's terraform Jupiter!
- Replies:
**26** - Views:
**6419**

### Re: Let's terraform Jupiter!

gladiolas wrote:But eventually, a solid surface forms

From what? Isn't Jupiter 90% hydrogen?

As long as we're doing megaengineering, maybe you could drop a rocky planet into it?

- Mon Sep 08, 2014 12:07 am UTC
- Forum: Science
- Topic: Schrodinger Cat Disproof (Samuel Jacobs)
- Replies:
**88** - Views:
**15461**

### Re: Schrodinger Cat Disproof (Samuel Jacobs)

"The cat is simultaneously alive and dead" also seems like the kind of trouble you can get into when you carelessly translate physics into everyday terms. "There are temporarily two cats, one alive and one dead" might not be a terrible alternate translation, and completely sidest...