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SHISHKABOB posted:There are some cases in which MOND works decently, like I think galaxy rotation curves. But in the Bullet Cluster it does not work very well. The Bullet Cluster is a cluster of galaxies where originally there were two clusters but they collided. The one kind of shot through the other. Gravitational forces caused most of the gas to be stripped from the one, but its dark matter, being far less influenced by gravity, basically kept going. So it's almost like it's been peeled. Right, I meant it doesn't work in a general sense. And there are papers even recently that still test it in simulations, but the general consensus is that there are a lot of things MOND fails to reproduce including your example of the Bullet Cluster as well as other scenarios in simulations.
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Nov 24, 2016 16:43
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Its bad.
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Nov 24, 2016 16:50
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dark matter is the final form of what intelligent civilizations evolve into, once they reach the technological singularity. it doesn't interact with normal matter for efficiency. the WIFI signal of the universe is gravity waves, got to keep it clear so you can get 4 bars between galaxy clusters
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Nov 24, 2016 16:53
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SHISHKABOB posted:Its bad. My grad school galaxies/cosmology class was taught by one of the main guys on the bullet cluster paper so he had some pretty strong feelings about mond that were passed on to me so I may be biased, but yes I think that is a fair statement.
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Nov 24, 2016 16:58
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Whoah same but undergrad. At least I think he was on the paper. He's on the wiki page.
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Nov 24, 2016 17:07
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I wish Commie Ned Flanders post count had less mass
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Nov 24, 2016 17:36
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posting from inside a black hole rn
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Nov 24, 2016 17:39
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yeah I eat rear end posted:You're probably joking but they did and called it Modified Newtonian Dynamics and was taken semi-seriously for a year or two until it was shown that it fails in many ways. There are still people who really believe in it in the community though and are widely considered hacks. I actually am fascinated by the concept of dark matter, even though I don't really understand it. It's interesting to me that they can only infer it through its gravitational effects and not directly observe it, despite all the crazy tools that exist nowadays. Is it because it doesn't reflect any light whatsoever, or what? e: to make matters worse there's also dark energy what is that poo poo Phlegmish fucked around with this message at 18:09 on Nov 24, 2016 |
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Nov 24, 2016 18:06
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Rutibex posted:dark matter is the final form of what intelligent civilizations evolve into, once they reach the technological singularity. it doesn't interact with normal matter for efficiency. the WIFI signal of the universe is gravity waves, got to keep it clear so you can get 4 bars between galaxy clusters dark lives matter
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Nov 24, 2016 18:44
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Phlegmish posted:I actually am fascinated by the concept of dark matter, even though I don't really understand it. It's interesting to me that they can only infer it through its gravitational effects and not directly observe it, despite all the crazy tools that exist nowadays. Is it because it doesn't reflect any light whatsoever, or what? Unfortunately there's no definitive answer to either yet. I believe the best candidate for dark matter (with the caveat that cosmology isn't my specialization) are weakly interacting massive particles (WIMPs) which basically only interact with other matter by gravity and the weak force. There are other candidates, ranging from "maybe" to "pretty unlikely", but so far we haven't confirmed it and would be big news when/if it happens. There are instruments designed to try and detect these things (LUX for example for WIMPs), but to my knowledge haven't had any detections. As for dark energy, I know even less about it so I don't feel qualified to comment on it beyond what I've read on wikipedia and what little I remember from my classes.
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Nov 24, 2016 18:46
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yeah I eat rear end posted:As for dark energy, I know even less about it so I don't feel qualified to comment on it beyond what I've read on wikipedia and what little I remember from my classes. if the universe was an goatse man, dark energy would be his fingers
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Nov 24, 2016 19:40
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Dark matter is cool because they call it stuff like WIMPs and MACHOs.
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Nov 24, 2016 20:37
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don't forget RAMBOs
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Nov 24, 2016 21:48
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They say you can't know a particle' position and momentum at the same time. But what if you just grabbed it with some tweezers. Then you know where it is (between the prongs) and it's momentum (none because you're holding it still. Boom.
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Nov 24, 2016 22:13
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Ograbme posted:They say you can't know a particle' position and momentum at the same time. But what if you just grabbed it with some tweezers. Then you know where it is (between the prongs) and it's momentum (none because you're holding it still. Boom.
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Nov 24, 2016 22:21
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Ograbme posted:They say you can't know a particle' position and momentum at the same time. But what if you just grabbed it with some tweezers. Then you know where it is (between the prongs) and it's momentum (none because you're holding it still. Boom. It's an equation that says there's a limit to how well you can know both position and momentum. Uncertainty on both of those multiplied together has to be at least as or bigger some little constant with planck's constant. Things have momentum even when they're sitting still. It's an intrinsic quality.
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Nov 24, 2016 22:57
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If something was truly sitting still in a reference frame then it wouldn't have momentum in that frame. It would also be 0 kelvin which is a nono as far as we know so its probably fine to say everything has momentum even if its the tail wagging the dog.
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Nov 24, 2016 23:02
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Let us English posted:If you think information only exists in the minds of humans I have a perpetual motion machine to sell you. ughhh
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Nov 24, 2016 23:33
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I watched interstellar op ask me
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Nov 24, 2016 23:34
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Blockade posted:As for what goes on on the other side of the event horizon, its not meaningful lmao you're the loving worst scientist ever what the christ
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Nov 24, 2016 23:35
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what happens in the dark, who cares, I can't see it, better not waste time thinking about it
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Nov 24, 2016 23:36
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I know what's in a black hoe A little bit of me 
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Nov 24, 2016 23:37
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SHISHKABOB posted:It's an equation that says there's a limit to how well you can know both position and momentum. Uncertainty on both of those multiplied together has to be at least as or bigger some little constant with planck's constant. It's cool cause it seems like some dumb math mistake with doing Fourier transforms but then nope the universe hosed up its math too
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Nov 24, 2016 23:39
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Modest Mao posted:what happens in the dark, who cares, I can't see it, better not waste time thinking about it You COULDNT think about it if you were in a black hole. 
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Nov 24, 2016 23:41
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dark matter is like, yo we added up all the stars in this region and there's way more gravity than what the stars alone would have so I guess there's some stuff we can't see?? maybe some added 'dark' stuff to fudge the math would be good dark energy is like, yo we added up all the energy in this region and there's way more energy than we can see so I guess there's some more energy?? and it scales in a hosed up way, maybe some added 'dark' stuff to fudge the math would be good Modest Mao fucked around with this message at 23:45 on Nov 24, 2016 |
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Nov 24, 2016 23:43
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ClamdestineBoyster posted:You COULDNT think about it if you were in a black hole. yeah I could, but the emission and absorption of electrons which are the chemical and electrical impulses we call thought would all have no causual impact on the universe I left behind
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Nov 24, 2016 23:44
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Modest Mao posted:dark matter is like, yo we added up all the stars in this region and there's way more gravity than what the stars alone would have so I guess there's some stuff we can't see?? maybe some dark stuff to fudge the math why can't scientists just admit they just don't know everything rear end in a top hat smarty pants scientists
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Nov 24, 2016 23:45
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It's clearly God loving with them
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Nov 24, 2016 23:46
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If 2016 taught me anything it's that the Hubris of man knows no bounds, and that God has a good sense of humor
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Nov 24, 2016 23:47
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Modest Mao posted:dark matter is like, yo we added up all the stars in this region and there's way more gravity than what the stars alone would have so I guess there's some stuff we can't see?? maybe some dark stuff to fudge the math i didn't know there was another kind of matter other than dark matter. It all seems dark to me. 
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Nov 24, 2016 23:49
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ur blind dummy hope your text to speech didn't read this in too mean a tone
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Nov 24, 2016 23:50
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I usually think of dark energy in relation to the universe's rate of expansion. Since matter and energy are basically the same, it's the same idea as dark matter. Space is getting pushed bigger but it's being pushed by 70% poo poo we got no clue what. It's a bit more abstract since it's expansion of space but it's all still pressure.
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Nov 25, 2016 00:45
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zedprime posted:If something was truly sitting still in a reference frame then it wouldn't have momentum in that frame. It would also be 0 kelvin which is a nono as far as we know so its probably fine to say everything has momentum even if its the tail wagging the dog. Why is that a no-no? Because of cosmic background radiation? e: and also quantum jitters? Yeah I'm just throwing out concepts here Phlegmish fucked around with this message at 08:20 on Nov 25, 2016 |
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Nov 25, 2016 08:17
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Its a nono because of the laws of thermodynamics.
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Nov 25, 2016 14:16
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im always sitting still in my own reference frame. owned physics
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Nov 25, 2016 14:30
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Phlegmish posted:Why is that a no-no? Because of cosmic background radiation? I know just enough about quantum mechanics to be completely wrong about everything so this thought experiment might get me into trouble, but consider the idea of holding something still. To make it the absolute easiest, lets think about holding an electron still with an array of electromagnets. On paper, you should be able to make a field with the right geometry and strength that you think it should hold the electron still in one place and you can say suck it nerds, I know the speed and location. However the electron isn't going to take this sitting down, it has its own movement and magnetic field and the magnets can feel it. The magnets might only just barely vibrate slightly more along a bond, but it means the electromagnets field isn't going to be that perfect on paper field and you're still left with a probability field where you might find the electron because everything is slightly vibrating around.
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Nov 25, 2016 15:02
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zedprime posted:In thermodynamics, to get to a lower energy state you can only subtract a number smaller than your current energy because energy needs to travel from big to small. When your only operation is subtracting a smaller number from a bigger number, you can never reach 0 without an infinite number of operations. Isn't everything quantised though? So you eventually get to 1 base unit of temperature and never any further because there's no whole number smaller than 1.
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Nov 25, 2016 15:18
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Woden posted:Isn't everything quantised though? So you eventually get to 1 base unit of temperature and never any further because there's no whole number smaller than 1. Temperature is derivative of (linear) momentum which if found to be quantized would uproot huge portions of thermodynamics and general relativity.
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Nov 25, 2016 15:37
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Commie NedFlanders posted:is it true that nothing beyond the event horizon can be directly observed? no, you can directly observe it from inside the event horizon yourself money doesn't cease to exist just because you put it in a safe
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Nov 25, 2016 16:42
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my daughter used to cry whenever I'd hide my face behind my hands because she didn't have object persistence yet so when my face disappeared she thought i was ceasing to exist because i couldn't be directly observed anymore. but now she's older and on track to be valedictorian and dating the captain of the football team and is super popular whereas when i was in high school i was kinda the class nerd so what do i know, right? i guess what i'm trying to say is maybe she had it right all along black holes work the same way
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