00:00:00 this basically disproved time travel 00:00:16 [23:58] MissPiggy: but it would just be duplicating me, and destroying the original 00:00:16 all the cells in your body are replaced etc 00:00:17 alternatively 00:00:18 samething 00:00:30 also, no it did not disprove time travel, physics did 00:00:50 anyway 00:01:13 The duplicating-and-destroying argument has absolutely nothing to do with disproving something that appears to be time travel. 00:01:25 Our current understanding of physics does not predict the physical possibility of time travel ... that is not the same as disproving it. 00:02:13 -!- BeholdMyGlory has quit (Remote host closed the connection). 00:03:36 The way to disprove time travel is to conclusively show that a) our knowledge of physics precludes all forms of time travel b) our knowledge of physics is entirely perfect. 00:04:00 The "b" part is the nonsense part :) 00:04:07 Well, part b) is the easy part. 00:04:19 ... No. 00:04:22 Derive all our knowledge of chemistry from our knowledge of physics. 00:04:27 Part b is impossible. 00:04:30 Boom! You've proved our knowledge of physics correct. 00:04:42 Part b) is about as impossible as proving that Barack Obama is the president of the United States. 00:04:43 Not /all/ of it. 00:04:44 uorygl: No, you've proved our knowledge of physics consistent with our knowledge of chemistry. 00:04:51 Or that our knowledge of chemistry is flawed 00:05:23 You need to demonstrate that our knowledge of physics is consistent with the universe. 00:06:02 Suppose we have a small set of rules that predicts a huge set of results. 00:06:03 In its entirety. 00:06:14 Which means you need to enumerate all infinity physical possibilities and bring them to pass. You need to destroy the universe by every means that the universe can be destroyed, and oh wait hm that last one was a problem. 00:06:20 Then it can predict those results. 00:06:25 -!- BeholdMyGlory has joined. 00:06:44 And we will be happy to use them to predict others. However, we have not proven those other results. 00:06:51 We merely assume them. 00:06:52 Um, let my try again. 00:08:59 Suppose that we have a complete theory of physics, and a huge body of data about chemistry. The body of data about chemistry is much, much larger than the theory of physics. And the complete theory of physics completely predicts that huge body of data. As long as you can be confident that no other complete theory of physics also predicts this body of data, you can be confident that the theory of physics is correct. 00:09:16 ut the data hand't been correleated in all possible ways yet 00:09:23 and eternity passed.. 00:09:30 Why would we want to do this? 00:09:41 We don't care about absolute proof. 00:09:44 And it came to pass that AC learned how to reverse the direction of entropy. 00:09:48 -!- FireyFly has joined. 00:09:54 We care about very, very strong proof. 00:10:00 -!- FireyFly has quit (Read error: Connection reset by peer). 00:10:10 That's not a proof. 00:10:32 You have either proven something or disproven something. There are no degrees. 00:10:33 We care about very, very strong evidence. 00:10:41 uorygl: chemistry involves mainly things composed of protons, neutrons and electrons. these are composed of less than a third of the elementary particles already known to physics (electron, up and down quark) 00:10:45 Yes, we care about very, very strong evidence. 00:10:56 And it is certainly possible to have very strong evidence that something cannot happen. 00:11:04 This is entirely different from "proving it cannot happen". 00:11:10 Never mind that the physics required to explain chemical reactions bears little resemblance to the physics required to explain orbits of planets. 00:11:27 so chemistry only tests a small part of the fundamental theory 00:11:36 I, personally, feel that we have little enough evidence against time travel that even a colloquial use of the term "disprove" is wildly overzealous. 00:12:02 we do not have any evidence against time travel generally 00:12:06 She uses the word “algebra” broadly, defining it as a “method of solving problems by honest confession of one’s ignorance”. 00:12:10 Gregor: Indeed. 00:12:12 I might argue that chemical properties are an extremely sensitive function of physical constants. 00:12:15 But maybe they're not. 00:12:19 however we lack any good theory of time travel that current models would allow 00:12:20 We actually just plain don't know enough to rule it out. 00:12:38 coppro: We also lack comprehensive models. 00:12:44 I sort of wonder what a "proof" is if it's not just very, very strong evidence. 00:12:48 uorygl: it would be like claiming you knew everything about C++ from just knowing the subset in common with C 00:12:49 of course we do 00:13:03 if we had a comprehensive model, physics would be boring 00:13:07 MissPiggy: Where are you getting this from? Sounds like lit-crit mumbo-jumbo 00:13:30 oerjan: yes, I understand what you're saying. One of my conditions was "as long as you can be confident that no other complete theory of physics also predicts this body of data". 00:13:34 uorygl: See mathematical proofs. 00:13:52 cpressey, it's about the book philosophy and fun of algebra 00:13:58 I am confident that no other program computes THIS algorithm! 00:14:02 And when I say "no other complete theory of physics", I mean "no other complete theory of physics that's nearly as simple". 00:14:16 -!- alise has quit (Quit: alise). 00:14:17 And by "other", I mean "different", as in "predicting different things". 00:14:21 uorygl: "Proof" is meaningful only when something can be comprehensively reduced to something else. That is, proof is contextual. It may be possible to prove that our understanding of chemistry is consistent with our understanding of physics, but this proof gives us little, as its utility is dependent on the proof of physics, which we have nothing to reduce to. 00:14:31 pikhq: so are "proof" and "mathematical proof" the same thing? 00:14:41 If he's not back in $soon, I'll worry. 00:14:51 No, but Hume a few bars and I'll fake it! 00:14:56 /rimshot 00:15:02 Colloquially, "proof" just means "very strong evidence" of course, but we're talking about theoretical physics, this is not a colloquial conversation. 00:15:35 uorygl: In any sane formal context, yes. 00:16:11 Prove that the sun will come up tomorrow. 00:16:15 And as we all know, you can't actually prove anything about reality with math. Just something about a nice formal system. 00:16:24 Alternately, make yourself sick worrying that it won't. 00:16:30 cpressey: easy. 00:16:35 cpressey: I sincerely hope it won't, the physical ramifications of the sun moving in such a fashion are horrifying. 00:16:44 no physical theory is proven 00:17:02 cpressey: it has come up every day for the past 1,000,000,000,000 days. We have no good reason to expect that it won't come up tomorrow. Therefore, it will come up tomorrow. 00:17:04 cpressey: Now, if you mean that the Earth will rotate such that from my perspective the sun's position on the horizon rises, that's a different request. 00:17:12 what about elecrtroonics 00:17:12 uorygl: Failure. 00:17:27 Gregor: I argue that it does, in fact, rise 00:17:29 uorygl: You've been around for a trillion days? Impressive. 00:17:33 uorygl that is such a fail argument 00:17:47 (I'm merely poking the most obvious of holes in that argument :P ) 00:17:49 and the other planets rotate the sun as it rotates Earth 00:17:49 uorygl: A lack of a proof against is not a proof for. 00:17:51 induction just doesn't work that way 00:18:00 Well, every bird I've ever seen has been black. Therefore, all birds are black. 00:18:05 What do you mean, induction doesn't work that way? That's precisely how induction works. 00:18:06 coppro: There is no global definition of "up" 00:18:12 you build an explanation of something which doesn't have variables 00:18:12 uorygl: No it's not. 00:18:15 cpressey: you've seen 1,000,000,000,000 birds? 00:18:20 if it fits wear is 00:18:20 pikhq: how do you think it works, then? 00:18:22 coppro: Erm, "global" is a bad term to use ... 00:18:22 it* 00:18:23 Gregor: nothing is defined globally 00:18:27 uorygl: You've seen 1,000,000,000,000 sunrises? 00:18:35 one of the great things of physics 00:18:44 Even better: birds have two wings. Therefore, if a bird loses a wing, it's no longer a bird. 00:19:14 what *is* a bird ? 00:19:18 Well, it;'s not the bird it used to be, anyway. 00:19:19 How much of a sapiens' brain do I have to scoop out before it's no longer a sapiens? :) 00:19:27 Okay, here's a better argument. 00:19:33 http://www.youtube.com/watch?v=wfvEgWINUFc <-- tries to answer that question 00:19:47 nah, the old one is fine 00:19:54 uorygl: I think it works by showing that some statement x in an infinite sequence is true, and that *if any statement in that infinite sequence is true*, then so is the next one. 00:19:54 The Sun has come up every day for the past 1,000,000 days. We have no good reason to expect it won't come up tomorrow. Therefore, it will come up tomorrow. 00:20:06 pikhq: that's an entirely different type of induction. 00:20:11 uorygl stop :((((( 00:20:16 it's a perfectly valid physical theory 00:20:18 uorygl, these kind of arguments make me die inside 00:20:19 Oh, you mean inductive reasoning. 00:20:20 uorygl: You are providing a very compelling /argument/ that the sun will come up. You are NOT proving that it will. 00:20:20 Mathematical induction and inductive logic are not the same thing. 00:20:28 Which is proves nothing. 00:20:30 and calling it "induction" is just as bad 00:20:34 no theory proves anything 00:20:42 MissPiggy: well, please stop dying so much. 00:20:48 Inductive reasoning produces a scientific theory. 00:20:52 Gregor: sure, define "proof" that way. I don't like that definition. 00:20:54 the theory is consistent with observations and makes a prediction 00:20:57 It is not a proof by induction. 00:20:57 uorygl, it should be called the principle of probable monotony 00:21:03 therefore is valid 00:21:03 heuristic principle of probable monotony 00:21:05 MissPiggy: then call it that. 00:21:06 *** 00:21:15 Gregor: general relativity allows you to treat any object as stationary, including the earth. see also http://xkcd.com/123/ 00:21:29 *any one 00:21:50 uorygl, I have a distaste for the heuristic principle of probable monotony because it is a very flawed to conflate this argument with an explanation -- which leads to much deliberation an quibbling on trivial matters 00:22:13 truly it is just a suggestion that one might look for a deeper explanation 00:22:32 oerjan: xkcd #123 doesn't actually use general relativity 00:22:34 it should not be confused with extrapolation either 00:22:36 Anyway, I think it's best to define proof as very, very strong evidence. There's really no practical difference between very, very strong evidence and absolute proof. 00:22:43 which is only valid when the frame of reference is not accelerating 00:22:56 coppro: no, that's _special_ relativity 00:23:18 MissPiggy: the fact that you have a distaste for it and it leads to much quibbling over trivial matters has no bearing whatsoever on whether it forms a strong argument or not. 00:23:26 general relativity is all about acceleration (and its equivalent, gravity) 00:23:36 oh wait, you're right 00:23:38 never mind me 00:23:38 uorygl I thuoght it did 00:23:50 -!- alise_ has joined. 00:23:53 uorygl: "Strong argument" has a completely different notion in math and in science. 00:24:07 A "strong argument" in math is a proof. 00:24:23 A "strong argument" in science is noting that every single time you do something, the same thing happens. 00:24:28 MissPiggy: well, it doesn't. 00:24:44 ufhG! 00:24:50 I must defeat this argument 00:25:57 uorygl: In conclusion: do not invoke the word "proof" unless you are discussing formal reasoning. It is wrong. 00:26:15 Or hard liquor. 00:26:18 it has been shown many times that an even which seems periodic or caused by some effect must not be assumed so simply on the evidence of data but if we can build a simple theory to explain this data 00:26:27 pikhq: so what word am I supposed to use for very, very strong evidence that's practically identical to a proof? 00:26:30 an event* 00:26:38 Evidence. 00:26:54 "Evidence" and "very, very strong evidence that's practically identical to a proof" are not synonyms. 00:27:19 "Since there is evidence that you are guilty, I hereby sentence you to life in prison." Doesn't sound right. 00:27:40 * cpressey invents the word "Gwandocu" for uorygl's use. 00:27:44 Thank you. 00:27:59 yes! 00:28:17 The reasoning is "Since there is evidence beyond a reasonable doubt that you are guilty", BTW. 00:28:36 So, if we had a complete theory of physics, it wouldn't necessarily be difficult to come up with gwandocu that it's correct. 00:28:58 "Complete theory"... Could you define that term? 00:29:20 (I presume you mean "theory that explains all observations", but just wish to confirm) 00:29:29 A complete theory is a full mathematical description of everything that happens. 00:29:30 But you could always find people who would not be persuaded, no matter how geemorgul the gwandocu. 00:29:33 So yeah, that. 00:29:52 cpressey: indeed; we call those people irrational, and we try to make them rational so that they believe. 00:29:55 Okay, then. I agree with that statement. 00:30:06 And note that scientific discussion needs the word "gwandocu". 00:30:11 O jeh, o naw, o naw, o naw, o naw. 00:30:49 -!- pikhq has set topic: "Gwandocu (n): Extremely strong evidence, far beyond a reasonable doubt." | alise sighting counter currently out of order | http://tunes.org/~nef/logs/esoteric/?C=M;O=D. 00:33:48 clearly an ancient welsh concept 00:34:13 Has too many vowels. 00:34:28 Would need to be "Gwndycu". 00:34:55 You managed to not turn the easiest-to-turn-into-a-consonant vowel into a consonant. 00:35:26 So I was being consistent with Welsh phonology. 00:35:39 -!- alise_ has quit (Ping timeout: 252 seconds). 00:36:48 -!- augur has joined. 00:36:56 If I had more time, I might ask if anyone thinks it's possible to get a complete mathematical description of everything that happens without being omniscient. 00:37:18 I think it's probably possible. 00:37:33 I have no idea what's happening in the Zeta Reticuli system right now. 00:37:50 I have some idea of what's happening in the Zeta Reticuli system right now. 00:37:56 First-hand? 00:38:03 No. 00:38:03 Can I borrow your saucer? 00:38:06 Drat. 00:38:16 So, you have a guess as to what's happening there, then. 00:38:24 Yes, but it's a very good guess. 00:38:32 Well, that's hard to know. 00:38:41 Without a saucer and all. 00:39:33 oh man ive got some many awesome ideas for my game :D :D :D 00:39:40 I wonder if there's any way of verifying that at least some of our laws of physics apply to Zeta Reticuli. 00:39:56 uorygl: ofcourse there are. 00:40:23 I guess we can look at the spectra emitted by the stars and see that they look like black body emission spectra. 00:40:40 And... we really have a lot of data on them. 00:40:40 -!- alise has joined. 00:40:55 we look at Z Reticuli and can observe that the star's size matches what we'd expect from its mass, that this correlates from the expected composition which we can find from its spectra 00:41:04 cpressey: i think if something like wolfram's theory that the universe is generated by a small program is true, then we might eventually find it (or an equivalent program), although we would never be able to prove that it was completely accurate 00:41:29 we can find that it's shape/oblation fits its rotational period 00:41:54 because we could never be sure that we have measured every phenomenon to perfect precision 00:41:55 we can see that it has the same gravitational effects on surrounding stars as its mass would dictate, and that it is affected by the background gravity accordingly 00:41:57 etc etc 00:43:38 Of course, we might be able to find gwandocu that it's completely accurate! 00:43:51 gwandocu? 00:43:54 oerjan: I'll bet it's "Hello, world!" 00:44:02 Later, folks. 00:44:09 -!- cpressey has left (?). 00:44:18 Gwandocu is extremely strong evidence, far beyond a reasonable doubt. 00:44:19 cpressey: that seems to lack a certain necessary complexity 00:44:44 -!- FireFly has quit (Remote host closed the connection). 00:44:53 "Hello, world!" isn't a computer program. 00:44:57 -!- BeholdMyGlory has quit (Read error: Connection reset by peer). 00:45:23 uorygl: it is in some languages! 00:45:29 also, what language is gwandocu :| 00:45:50 English. 00:45:58 #esoteric Vernacular English. 00:46:01 oic 00:46:27 Etymology: pronouncable series of letters, chosen on a whim. 00:46:40 ;) 00:47:44 i still say it's welsh 00:48:04 In Welsh it's Gwndycu. 00:48:28 -!- sebbu2 has joined. 00:49:22 -!- sebbu has quit (Ping timeout: 264 seconds). 00:49:22 -!- sebbu2 has changed nick to sebbu. 00:49:26 pikhq: gwendolyn is a welsh name you know. it's not that far off. 00:52:47 gun-dick-oo 00:53:00 Yeah. 00:56:01 -!- sebbu has quit (Ping timeout: 264 seconds). 00:56:08 -!- sebbu has joined. 00:56:14 Gregor: general relativity allows you to treat any object as stationary, including the earth. see also http://xkcd.com/123/ 00:56:41 oerjan: Well, not quite, Earth is in an accelerated frame of reference, but anyway, even so the sun most certainly does not come "up", up would be away from the Earth. 00:58:11 Gregor: the sad thing is that he gets it backwards :( 00:58:15 general relativity allows you to treat an accelerated frame as stationary ;D 00:58:18 (it 00:58:25 's just a coordinate choice) 00:58:27 construct newtons laws in a rotating frame and you see there is no centrifugal force 00:58:51 augur: um, no? 00:58:58 oerjan: um, yes? 00:59:02 Yeah, I'm gonna go with "um, no" on this. 01:00:37 oerjan: I think that everything is definable in a reference frame, but not consistent with the behavior of a stationary frame: From an accelerated frame, all other objects appear to be accelerating conversely, but with no force acting upon them. That's inconsistent. 01:00:45 unless what you mean by "get a centrifugal force" is if you calculate something based off of where the revolving object would've gone were it not kept in a circular path by a centripetal force. 01:01:22 but thats inventing a force based on what WOULD have been not what is. there is no centrifugal force that emerges from newtons laws in a rotating reference frame. 01:01:23 Gregor: general relativity treats that as a gravity field caused by the metric of spacetime 01:01:43 there is only a centripetal force and momentum. 01:01:55 augur: do you understand what "in a rotating (coordinate) frame" means? 01:02:08 yes, i do. 01:02:18 oerjan: Oh wait ... this is one of the properties of /general/ relativity that distinguishes it from /special/ relativity, innit? My general rel. isn't up to snuff :P 01:02:35 Gregor: yeah. 01:03:13 don't worry, mine isn't up to much more than that either. i certainly cannot calculate spacetime tensors... 01:03:41 you cant calculate kinematic vectors, nevermind spacetime tensors, apparently. 01:03:59 * oerjan swats augur -----### 01:04:08 -!- dev_squid has joined. 01:04:17 it doesnt help you that im a masochist. :P 01:05:27 oerjan: He's telling you to swat him again. 01:06:02 augur: if you turn on a centrifuge, and then describe everything happening inside from the viewpoint of a coordinate system moving _with_ the centrifuge, then clearly in that coordinate system there is an acceleration of things 01:06:16 no, there isnt. 01:07:41 -!- ruhtranayr has joined. 01:07:55 an object moving at zero velocity outside of the rotating frame will trace a circular path in the rotating frame, which is acceleration 01:08:23 um, yes. that's "yes, there is.", by the way 01:08:25 an object revolving at the same rate as the frame does not move in the frame, maintaining the same coordinates, thus not accelerating 01:08:56 centrifugal force is not the acceleration of the externally stable object. 01:09:05 augur: sheesh, we are talking about describing _ordinary_ physics from the viewpoint of a rotating frame 01:09:16 afk 01:10:01 actually, brb 01:14:09 -!- MissPiggy has quit (Quit: Lost terminal). 01:14:13 -!- augur has quit (Ping timeout: 245 seconds). 01:24:38 -!- MizardX has quit (Ping timeout: 258 seconds). 01:33:49 -!- dev_squid has quit (Ping timeout: 264 seconds). 01:35:26 I wrote a BF interpreter in C. Why did I write a BF interpreter in C? 01:35:48 * pikhq tries to trace back to the start of the reasoning... 01:36:02 -!- dev_squid has joined. 01:36:22 Oh, right. I had tried in the past (ages ago) and failed horribly. Somehow I went from there to "I should write one." 01:36:52 http://sprunge.us/LBeW 01:36:57 Least useful program I've written in ages. 01:40:13 Also probably the cleanest C I've written this year. :P 01:51:51 Meanwhile, I present the ugliest car ever created: http://www.carsweb.cz/hatt/novinky/golba/golba_1.jpg 01:56:18 -!- SimonRC has quit (Ping timeout: 265 seconds). 01:56:32 Dear God. It is ugly. 01:59:03 I'm not sure what to say. 01:59:20 Depending on your perspective, it either has tits or testicles. 02:05:53 -!- SimonRC has joined. 02:07:03 :D 02:07:11 I was going for alliteration there, but in retrospect, "boobs or balls" would have worked better. 02:13:23 -!- jcp has joined. 02:17:04 -!- Sgeo_ has changed nick to Sgeo. 02:26:26 "The result was speedy no consensus." —Articles for Deletion 02:27:22 who says wikipedia isn't efficient 02:36:13 alise: lol 02:36:21 That ... what? 02:36:34 http://en.wikipedia.org/wiki/Wikipedia:Articles_for_deletion/Dwm_(2nd_nomination) 02:36:43 -!- coppro has quit (Remote host closed the connection). 02:36:47 Guys/ 02:36:49 *Guys. 02:36:52 Hello. 02:39:26 Are there any programs out there that would let be experiment with computer circuitry and logic gates and stuff like that? 02:39:54 -!- coppro has joined. 02:40:08 -!- alise has quit (Quit: alise). 02:40:28 -!- sebbu has quit (Ping timeout: 245 seconds). 02:41:15 -!- sebbu has joined. 02:43:22 dev_squid: scarf is the expert on that stuff here i believe 02:44:17 as in, he actually does research with it 02:45:33 vhdl is a keyword to look for 02:48:00 I see. 02:48:21 Would a Von Neumann Automaton simulator fit my needs? o.o 02:49:36 the cellular automaton thing? that seems a bit different from real circuits 02:50:20 I think so. 02:50:25 Yeah, I assumed as much. 02:50:25 ... a Von Neumann Automaton is presumably, based on the name, not a cellular automaton or even anything particularly similar to a cellular automaton ... 02:51:05 Gregor: http://en.wikipedia.org/wiki/Von_Neumann_cellular_automaton 02:51:23 Oh, interesting :P 02:51:29 It falls under the category of an automaton, but it can be used to construct CPU models. 02:52:05 dev_squid: note that "automaton" includes more types than cellular ones 02:52:21 Oh. 02:52:38 Absolutely. 02:52:43 turing machines, for example 02:52:56 (although those are easy to simulate with cellular ones) 02:53:09 You know what'd be cool? An esolang based on the Von Neumann Automaton. :) 02:54:25 Hahah! This looks PERFECT! (http://en.wikipedia.org/wiki/Wireworld) 02:54:56 Wireworld is good fun. 02:55:36 epic http://upload.wikimedia.org/wikipedia/en/f/f9/Golly_Constructor_layout.gif 02:57:37 Oh, you think THAT's epic?! Look at this one... 02:58:08 See the ticker GIF at the top of (http://golly.sourceforge.net/)? 02:58:37 -!- adu has joined. 02:58:45 heh, nice 02:58:54 That's an actual configuration which I BELIEVE is in Game of Life, but I can't tell. 02:58:57 it is 02:59:10 those are LWSS guns, I believe 02:59:11 It's one demo configuration in Golly. 02:59:21 That's sort of unbelievable. :) 02:59:34 actually, I don't know the specific term for those 02:59:45 since they're guns, but only trigger when a glider comes by and reflect the glider 03:03:31 I haven't even looked into Life enough to even know what you're talking about. :) 03:04:18 a spaceship is an element that moves on its own without leaving debris or anything; gliders are the basic spaceships that move diagonally 03:04:29 I see. :) 03:04:32 a gun is a pattern that generates spaceships 03:04:44 Cool. 03:04:46 in the right, you can see gliders going back and forth between reflectors 03:05:22 and when they get reflected on the middle reflectors, they generate horizontal spaceships 03:05:24 which make the pattern 03:06:32 I read in an article once that you could take a turing-complete automaton like Life and build a working program and that it would be the ultimate form of data compression. :) 03:07:12 huh? 03:07:22 why? 03:07:50 dev_squid: Doubtful. 03:08:00 Life takes quite a lot of memory. 03:08:32 Just what I read. 03:08:45 Hey... 03:09:30 So Wireworld is probably what I'm looking for? 03:10:56 * coppro wonders if someone has implemented FSG in Golly 03:16:34 you know, I sort of like this channel without alise being here all the time 03:18:05 What's wrong with alise? 03:19:20 Looks like I'm gonna be addicteed to this thing. 03:22:11 Just some random crap personal stuff. 03:25:33 -!- jcp has quit (Ping timeout: 240 seconds). 03:26:13 dev_squid: alise has a habit of loudly attacking anything he doesn't like 03:26:36 which is sometimes nice, sometimes not 03:27:22 -!- jcp has joined. 03:32:05 -!- jcp1 has joined. 03:32:08 -!- jcp has quit (Ping timeout: 245 seconds). 03:39:01 Ah. 03:39:04 -!- jcp1 has changed nick to jcp. 03:52:13 -!- ruhtranayr has quit (Quit: Leaving). 03:56:34 ....oooohhhkay 03:56:46 I just had deja vu, except it included stuff that did not happen. 04:01:17 -!- lament has quit (Ping timeout: 260 seconds). 04:02:15 -!- augur has joined. 04:02:25 oerjan: hello. 04:02:30 so to continue the previous discussion 04:02:34 noooooo 04:02:53 * oerjan beats augur with the saucepan to induce amnesia ===\__/ 04:03:13 an object that is experiencing the so called "centrifugal" force is an object revolving around some centerpoint 04:03:21 the force being away from that centerpoint 04:03:54 but in the rotating reference frame, the object is not moving at all, and thus is, relative to that frame of reference, not experiencing any forces 04:04:16 and thus there is no centrifugal force on it in the rotating frame of reference 04:05:00 now certainly its true that in the rotating f.o.r. an object stationary in the non-rotating f.o.r. will appear to move in a circle and therefore will appear to be affected by some force 04:05:06 but this force is centripetal 04:05:13 not moving at all isn't the same as not experiencing any forces - it just means the forces cancel out 04:05:29 ok, sure, but then the NET force is zero. 04:06:09 sure you could invent some imaginary centrifugal force that is perfectly counterbalanced by some other centripetal force, in this rotating f.o.r. 04:06:10 note that the object is pushed inward by the walls of the centrifuge 04:06:29 well yes, the object IS pushed inward by the wals of the centrifuge 04:06:33 -!- lament has joined. 04:06:34 but thats a centriPETAL force 04:06:40 not a centrifugal force. 04:07:10 augur: yes, but in the _rotating_ frame that is canceled _by_ the centrifugal force, precisely to allow the net force to be zero 04:07:36 oh i see what you're saying 04:07:42 wow 04:07:46 progress :D 04:08:39 e.g. if you had a mass on a spring, if you calculated the forces acting on the force, you would get that the mass is not experiencing non-zero "gross" force 04:09:10 for instance. im using a spring because the visual reasoning is easier in such a case 04:09:37 um is this spring inside the centrifuge, or is this completely unrelated? 04:09:40 yes, ok, definitely. in the rotating frame there would indeed be a centrifugal force. 04:09:48 yay 04:09:58 object on a spring, revolving around the spring's opposite end 04:10:18 so that the spring is stretched beyond it's normal length 04:11:12 but isnt changing, then if you rotated the f.o.r. with the spring, the spring's tensile properties wouldnt change, so the force must be changing 04:11:46 yes, thats interesting. good point. 04:13:16 i think the xkcd comic should have worded it more carefully. 04:14:08 because when i initially read it, i wasnt thinking in these terms, but rather in terms of just constructing the equations for circular motion in a non-rotating reference frame 04:15:59 mhm 04:17:29 but i think there is good argument that any such derivation of a force is genuinely illegitimate by arguing that rotating frames of reference aren't on the same footing as non-rotating frames of reference 04:18:34 e.g. from a rotating f.o.r. you would have to have some sort of "5th force" 04:19:39 see general relativity - you get something indistinguishable from a gravitation field 04:19:57 not gravitational in natural, but rather different, because it has no source, propogates infinitely fast, radiates in only two dimensions, and has a falloff such that all objects, regardless of mass, have precisely the same revolution rate 04:20:36 oh all objects moving the same regardless of mass _is_ a gravitational feature 04:20:46 aye 04:20:54 sorry no what i meant is distance, not mass. 04:21:15 they have same revolution rate but varying speeds of revolution 04:21:19 true 04:21:27 but this is NOT true of gravity 04:21:39 yeah, that probably has something to do with absence of (nonzero) spacetime curvature 04:21:44 infact, with a rotating frame, things can move faster than light. 04:22:03 yeah 04:22:19 the force seems to be really rather different than gravity 04:22:31 maybe its not, but it seems on its outward appearances to be quite different 04:22:53 sure 04:22:57 so is any force 04:23:11 (except, of course, for gravity) 04:23:16 but they are all indistinguishable from gravity in their effectrs 04:23:36 s/r[^r]+$// 04:24:17 right, but what im saying then is that accepting rotating reference frames as on equal footing with non-rotating references frames necessitates the existence of some sort of 5th force 04:24:29 maybe thats a moot point, right 04:24:44 maybe there is this fifth force, and it is generated by objects rotating 04:24:50 and it really does have these properties 04:25:28 oh food -> 04:25:44 iinm, people have analyzed magnetism as just an illusory relativistic version of the electrostatic force 04:27:08 but i think really the fact that this 5th force is so radically different, has no force carrier particles, is undetectable except by people in the rotating reference frame, etc. suggests that its not genuine. 04:27:29 Hm 04:27:43 i mean, maybe in some sense you could detect the frame dragging of the rotating object, but that would take non-zero time to detect from a non-zero distance 04:27:44 I should probably do something like retaking an online test I scored poorly on soonish 04:27:56 whereas the rotating frame would see this force as propogating instantly 04:28:06 Will be unable to in about half an hour 04:30:29 also, if we assume that rotating reference frames are genuinely as valid as other reference frames, you have a world in which things can accelerate and decelerate at rates that have no correlation with their mass, the and gain and loose energy on a whim for no apparent reason, but everything in the universe experiences these things simultaneously by necessity 04:31:00 augur: btw don't be so sure about no force carrier particles. see http://en.wikipedia.org/wiki/Unruh_effect 04:31:49 let me continue :P 04:31:56 although i guess that could be taken as a way to detect which frames were "really" non-accelerating 04:32:29 i mean, the point is, oerjan, accelerating frames of reference are not equivalent to non-accelerating frames of reference 04:32:51 the laws of physics as observed in them change. this is not true of a constant motion frame of reference 04:33:41 augur: i guess in general relativity it's actually _free-falling_ frames (which are not global btw) which are special, if any 04:33:57 he energy content of the universe would INCREASE 04:34:05 violating the laws of thermodynamics. 04:34:14 -!- Gracenotes has joined. 04:34:19