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11-22-2015, 10:16 PM | #61 | ||||
Minion of Satan
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Someone falling into a black hole wouldn't notice anything strange from their perspective (aside from being spaghettified if it were a smaller black hole, because the gravitational pull at your feet [assuming you fall feet-first] would be much stronger than the pull at your head]). I mean, yeah, you would probably die I think from the force, but assuming you could stay alive to notice things, you wouldn't notice anything odd about the region of space-time inside the event horizon, which you would have no idea you've crossed. From an outside observer, though, because of the way space-time is relative to the observer and the way that these Einsteinian equations that I don't know how to do work out, they would see you gradually slow down as you reach the event horizon, and they would never see you cross it. You would just stay hovering at the edge of it for the rest of eternity. Of course, they wouldn't really see you hovering there, because the light coming from just outside the event horizon is incredibly redshifted as to be indetectable (the energy of light is it's frequency). But, in principle, you would just be hovering there and would cease to move. So, what I'm wondering is, since we are all outside observers to whatever black holes we (indirectly) see, doesn't that mean that none of the black holes we see have their mass inside of them, because all their mass should be frozen just outside of them? I mean, I would guess that functionally, it'd make no real difference (we wouldn't be able to see it anyway, because of the infinite redshifting), but it seems in principle, it'd be true. Unless I'm missing something (which I probably am). Quote:
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We can also tell them from the X-rays produced from the accretion discs, like you guys mentioned. X-rays are just a high-energy form of light (high-frequency). If there is a star near the black hole, it'll suck matter from it, and that matter will swirl around in a disk as it falls in so fast that it gets really hot and emits X-rays. This light isn't really "escaping" the black hole, as it hasn't passed the event horizon yet. Quote:
The X-rays aren't coming from inside the event horizon, but the gases outside of it. So, they aren't really an exception to the "nothing can escape" rule. One way to think about it is by thinking about the world lines of objects. Like, if you could see all time at once instead of just a cross-section of it, you would be able to see the path you take through time. There are these diagrams that help us envision this by omitting a space dimension and adding the time one. Since the fastest anything can go is c, any event that has happened so far away from you that a photon emitted from it couldn't have reached you yet is outside of your "light cone." Further in the future, a larger region of space-time is inside this current space-time events light cone. But one second from this event, only things as far as 300 000 000 meters away are within its light cone. Anything you do now can't affect anything 600 000 000 meters away within one second. But in two seconds, something that far can be affected. The light cone forms the boundary of all the things in the universe that can have a causal influence on you, or that you can have a causal influence on. For a black hole, nothing inside of it can ever have a causal influence on us, because nothing can reach us from it. So, the black hole's interior is always outside our past light cone, and we are always outside the future light-cone of anything inside the black hole. So, the event horizon is like this boundary in space-time that subtends a region of space-time that we can never observe from our perspective. Not just because it's really dark and we can't see inside, but because these events, from our perspective, never happen. But they happen from the perspective of anyone inside of it. |
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11-22-2015, 10:30 PM | #62 | ||
Minion of Satan
Location: Banned
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Only sci-fi book I recall reading is I, Robot. It was pretty cool. I like it best when it's not just "lasers, lasers everywhere!", but instead talks about what the social implications of these technological advances would be. The book does this with robots, as well as plays with puzzle-like problems when shit goes down and scientists have to figure out what's going on using the three laws of robotics that are described. One sci-fi movie I love is Primer. It's about people who build a time machine, but instead of being this Back-to-the-Future or Terminator-like thing where it's like, "look, it's the '70s, and everyone has pimp hats!", the people only use the time machine to go back in time a few hours at a time, and it only works in real time; if you want to go back one hour, you have to sit in there for one hour. The narrative is a crazy clusterfuck that is hard to untangle, but actually follows its internal logic. But the beauty of the film is that it's not about trying to decipher the structure of the plot (though that's fun, too). It's about the affect the invention has on the lives of the two main characters, their actions and choices. Quote:
But, if the volume we're calling the black hole and assigning a density to is just the area within the even horizon, then they are not infinitely dense, and their density is just dependent on their size. Large black holes aren't very dense at all. Man, Interstellar is on Netflix now, and I've never seen it. Soon as winter break hits I'm watching the shit out of that. |
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11-22-2015, 10:36 PM | #63 |
BOTTLEG ILLEGAL
Location: I'm faced with so many changes that I just might change my face
Posts: 32,800
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you are good at explaining this stuff, disco king
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11-22-2015, 10:56 PM | #64 | |
Just Hook it to My Veins!
Location: N3t4Euh Haus
Posts: 32,752
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11-22-2015, 10:58 PM | #65 |
Just Hook it to My Veins!
Location: N3t4Euh Haus
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or like dark matter. We can't currently detect dark matter at all, but we know it must be there by deduction of how other shit in the universe works. kind of like a black hole?
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11-22-2015, 11:06 PM | #66 |
Just Hook it to My Veins!
Location: N3t4Euh Haus
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unless philosophically we accept the premise that reality can only exist through our observations (if a tree falls in a forest...) but I generally reject that. Our perceptions are very limited, but I don't really believe there is no physical universe beyond our brains.
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11-22-2015, 11:12 PM | #67 |
Braindead
Location: TX
Posts: 16,289
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So is there a center point within a black hole that is very dense or "infinitely dense"? and the rest of what we'd consider it to be is just the event horizon?
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11-22-2015, 11:19 PM | #68 |
Braindead
Location: TX
Posts: 16,289
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I remember reading this thing about Issac Asimov's three laws of robotics just this week and how absolutely impractical they would be to program into AI
"A robot can not cause harm to a human" is a statement absolutely loaded with human intuition a machine could not make sense of it. What is defined as "harm" what is the strict definition of "human" |
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11-22-2015, 11:28 PM | #69 |
Just Hook it to My Veins!
Location: N3t4Euh Haus
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my friend who has some out there ideas is always on about how if we learn to program robots to be utilitarian, they will eventually decide to kill us all to end our suffering.
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11-22-2015, 11:32 PM | #70 | |
Just Hook it to My Veins!
Location: N3t4Euh Haus
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I also read some shit in BBC science recently that, explained in my own probably incorrect terms, is that there are some astronomers who have been triangulating objects in deep space. Something about the math of these triangles consistently defies our understanding of how triangles are measured in 3 dimensions. However, if we just assume a 2 dimensional universe, the math all makes sense. |
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11-22-2015, 11:38 PM | #71 |
Braindead
Location: TX
Posts: 16,289
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Robots are scary yo
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11-22-2015, 11:49 PM | #72 | ||
Minion of Satan
Location: Banned
Posts: 8,874
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Thanks! I get most of my stuff from just browsing things that simplify science for laypeople, like YouTube videos and whatnot.
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My concern had more to do with what relativity says is happening in reality, not just what we can or cannot detect because of our instruments and technology. Like, a tenant of relativity is that space and time are relative to the observer. The reason for this is that the speed of light is constant for all observers. Like, if there were a car moving 50 km/h, and I were in a parked car, and you were in a car moving 25 km/h, the first car would be moving relative to me 50 km/h, whereas it would be moving relative to you 25 km/h. But it doesn't work the same with light. Even if we are moving at different speeds, we will still see light moving at 3.00 ×105 km/h, because that speed is absolute. So, in order to agree on the speed of light, as speed is distance ÷ time, we would disagree on distance and time. Distance and time are affected by the speed you're moving and the effect of gravity on you. This is why in order for GPS to work, satellites, which are farther from the earth than we are, have to take into account time dilation to work. This isn't something peculiar about how clocks work, it's how space-time itself works. So, the same equations that tell us how different observers should disagree on the time of the same event tells us that an observer will never see something fall past the event horizon of a black hole, not because of the lack of instruments available to see into it, and not because the light can't reach us, but because the observer outside and the observer inside will disagree on events. We will see an object approach the event horizon, gradually slowing down until it just freezes outside of it. From our reference fram, nothing happens to that object past that event. From the person going inside's reference frame, they do fall in, instead of just hovering there. Quote:
For any mass, there is a radius that, if all of it's mass were to be inside that radius, it's gravity would be so strong, it's escape velocity would be the speed of light. This is the Schwarzschild Radius. Due to Earth's gravity, a rocket needs a certain amount of speed to escape Earth. In a black hole, no amount of speed you could generate would allow you to escape, the gravity would be too strong. The surface of a volume with a Schwarzchild radius is the event horizon. This is the sphere that marks the boundary of the "point of no return." Once you're inside, you can't get out. So, if we call that whole object the "black hole," then black holes aren't necessarily super-dense. If we're just talking about the singularity, then they might be, but our current physics don't tell us a lot about singularities. They are pretty much just things where our current physics stop making sense. |
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11-23-2015, 12:02 AM | #73 | ||||
Minion of Satan
Location: Banned
Posts: 8,874
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I think the 2d surface of a black hole is important for some reason. Like, I think they say that all of the information about a black hole is encoded in it's surface. Although, the use of the word "information" in physics has always confused the shit out of me (has to do with states of particles and amounts of energy, I think?). I think they say information is the fundamental unit of nature, not energy (whatever that means). I think this has to do with the Wiki article Reprise linked, and with speculations about a holographic/2d interpretation of the universe. |
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11-23-2015, 12:05 AM | #74 | |
Just Hook it to My Veins!
Location: N3t4Euh Haus
Posts: 32,752
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11-23-2015, 12:15 AM | #75 | ||
Just Hook it to My Veins!
Location: N3t4Euh Haus
Posts: 32,752
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11-23-2015, 12:21 AM | #76 |
Braindead
Location: TX
Posts: 16,289
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Do we know anything about other dimensions other than guessing that they could exist?
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11-23-2015, 02:18 AM | #77 | |||
Minion of Satan
Location: Banned
Posts: 8,874
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The only thing I can think of that would complicate things is the idea that "a black hole has no hair," which is a metaphor for the idea that information "disappears" in a black hole, and the only information that describes the state of a black hole is mass. I think they mean by this that it doesn't matter what falls in, the sort of things that fall in have no effect on what the black hole will be like. Only the mass, spin, and charge matter, and only the mass, spin, and charge describe it. But, if all the stuff hasn't really fallen in yet, it would seem to me that, in principle, the surface would have the contours of everything just outside of it, and the information wouldn't be lost yet, so it would have "hair." A black hole that swallowed a potato would be distinguishable from a black hole of equal mass that swallowed an apple. I dunno, though. Quote:
http://www.stronggravity.eu/how-to-m...ack-hole-mass/ They could use gravitational lensing (bending of light) as well, I don't see why not. Quote:
From what I got from Hawking's A Brief History of Time, string theories came about to try to harmonize relativity and QM and get rid of the bizarre infinities that the combination of the two theories produces. The last attempt to do this, supergravity, fell apart, so string theory became the only game in town. I think that string theory is mostly conjecture that plugs in values, not because they are deduced from theory, but because they conform with already-existing observations. I think that it posits other dimensions to explain why gravity is much weaker than other fundamental forces. Like, gravity works in more dimensions or something. But there's the issue of the fact that orbits would be unstable and would not look like what they are observed to look like if there were more dimensions, so they conjecture that these dimensions are "small" and "curled up." I have no idea what that even means, though (I just think of a dimension as a direction perpendicular to other directions... so how can it have a "size" or be curled?). From what I get, it's mostly brute-force math to get things to make sense and conform to what we already know and harmonize things, but doesn't yet have any testable implications. Karl Popper would probably hesitate to call it a "theory," but I dunno, scientists are smarter than me, so even though it doesn't seem falsifiable, it seems to me that scientists have good reasons for pursuing it if they are. Maybe one day, technology will catch up to the point where we can actually test string theory, so working out the math doesn't seem a bad idea. The idea of multiple universes "stacked" is pretty cool. Like, there is another dimension perpendicular to the ones we know that we just can't access, because we're flatlanders. I remember Michio Kaku once saying that dark matter could be gravity from adjacent universes interacting with our own. Geek time: Earlier this year, DC Comics released a miniseries called "The Multiversity." It was this Grant Morrison story that was the standard DC Crisis "characters from different universes team up to save the multiverse" fare, but because it was Grant Morrison, it was a bit more than that, and used cool spacey ideas and post-modern techniques to sort of play with the conventions of comic-book story-telling. Before the comic was released, they released a "map of the Multiverse," which shows each of the 52 universes like this combination of an atomic diagram and those old-school celestial maps. We can't observe other dimensions, but string theories posit 10, 11, or 26 dimensions, depending on the theory. Other theories probably posit extra dimensions, too. But for now, we can't verify these through evidence, and they are just a consequences of the theories. |
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11-23-2015, 01:25 PM | #78 | |
Minion of Satan
Location: "I'm a quivering collection of the worst and least helpful emotions: fear, anxiety, terror, paranoia, indigestion, dishpan hands..."
Posts: 7,765
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but if they were making a movie about a war that happened in 1200 or whatever. Then they might. |
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11-23-2015, 08:39 PM | #79 |
Minion of Satan
Posts: 6,781
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Hands up if you've ever laughed at a Poots joke, guys.
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11-23-2015, 09:06 PM | #80 |
Minion of Satan
Location: Banned
Posts: 8,874
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There is a theory that infinite Pootses making jokes for an infinite amount of time would elicit a laugh eventually. There isn't yet consensus amongst the scientific community, but it sounds plausible to me.
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01-26-2016, 03:11 PM | #81 |
Just Hook it to My Veins!
Location: N3t4Euh Haus
Posts: 32,752
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07-01-2016, 03:03 AM | #82 |
Just Hook it to My Veins!
Location: N3t4Euh Haus
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aurora on Jupiter |
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07-01-2016, 09:54 PM | #83 |
Braindead
Location: Ignore List
Posts: 17,229
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I know this thread is about planets and that's kind of what I like, but this speaks to me the most here.
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07-01-2016, 09:56 PM | #84 |
Braindead
Location: Ignore List
Posts: 17,229
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It almost makes me as sad as pear shaped nuclei
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07-01-2016, 11:09 PM | #85 |
Just Hook it to My Veins!
Location: Donald Trump of Netphoria
Posts: 37,218
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R u hi
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07-01-2016, 11:30 PM | #86 |
Virgo
Posts: 42,781
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isn't that most peoples thoughts about AI?
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07-02-2016, 12:26 AM | #87 |
Braindead
Location: Ignore List
Posts: 17,229
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I guess equating inefficiency with suffering makes sense, yeah
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07-03-2016, 10:55 PM | #88 |
Brazilian Blouselord
Location: heavy metal pool party
Posts: 35,781
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07-03-2016, 11:15 PM | #89 |
Virgo
Posts: 42,781
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hell yea
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07-04-2016, 06:00 PM | #90 |
Demi-God
Posts: 388
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