• In a Nutshell - Black Holes Explained
    29 replies, posted
[video=youtube;e-P5IFTqB98]http://www.youtube.com/watch?v=e-P5IFTqB98[/video]
Probably the only black hole explanation video that doesn't include the term "spaghettification" which is a real scientific term that exists (not kidding, look it up) to designate something being stretched at an atomic level by a black hole's tidal force. [editline]15th December 2015[/editline] Usually that's even the highlight and it's totally accurate to boot. Was waiting for it but it never came.
[QUOTE=StrawberryClock;49325136]Probably the only black hole explanation video that doesn't include the term "spaghettification" which is a real scientific term that exists (not kidding, look it up) to designate something being stretched at an atomic level by a black hole's tidal force. [editline]15th December 2015[/editline] Usually that's even the highlight and it's totally accurate to boot. Was waiting for it but it never came.[/QUOTE] He already described it as your cells being pulled apart and would soon become one atom wide. The gravitational differential of the black hole is enough to do this, hell I wonder if it could break apart atoms and pull apart protons/neutrons into their subsequent quarks.
I remember when Kurzgesagt changed its name to In a Nutshell people thought they had become too mainstream and the quality of their content had dropped. How wrong they were.
[QUOTE=LoneWolf_Recon;49325730]He already described it as your cells being pulled apart and would soon become one atom wide. The gravitational differential of the black hole is enough to do this, hell I wonder if it could break apart atoms and pull apart protons/neutrons into their subsequent quarks.[/QUOTE] Yes.
The singularity doesn't always have to be a point! If the black hole is rotating, the singularity becomes a ring instead.
[QUOTE=JohnnyMo1;49327493]The singularity doesn't always have to be a point! If the black hole is rotating, the singularity becomes a ring instead.[/QUOTE] Is this something we know or something we think?
[QUOTE=paul simon;49327505]Is this something we know or something we think?[/QUOTE] to know is only to think you know
[QUOTE=paul simon;49327505]Is this something we know or something we think?[/QUOTE] Anything about the inside of black holes is "something we think" until we have a well-confirmed theory of quantum gravity. Even the existence of black holes is "something we think." We've never actually observed a black hole closely enough to be sure it was an object with an event horizon like we expect. Black holes just happen to be a model that fits very closely the properties of some things we see in space. So the subtext of my post was "within the context of classical general relativity," but since we can't even observe point singularities, and we don't know if singularities will survive in a theory of quantum gravity, that was the context of that part of the video too.
I heard an idea that our universe might be a 3D surface of a 4D black hole, "kinda like the black holes in our 3D universe have a 2D surface" and also that inside a black hole, "up" doesn't exist as a direction, and I can't wrap my head around that. If there is no "up" does that mean there is no "down"? Does that mean, when you fall into a black hole, you end up in Flatland, with outside of the black hole being the "past", center of the black hole being the "future", and the third spatial dimension just not existing any more? I hope I don't sound like a crazy person.
Holy crap 3 videos in one month
Really messes with the mind to think of the universe on such a fundamental, mechanical level.
[QUOTE=Nikita;49327719]I heard an idea that our universe might be a 3D surface of a 4D black hole, "kinda like the black holes in our 3D universe have a 2D surface" and also that inside a black hole, "up" doesn't exist as a direction, and I can't wrap my head around that. If there is no "up" does that mean there is no "down"? Does that mean, when you fall into a black hole, you end up in Flatland, with outside of the black hole being the "past", center of the black hole being the "future", and the third spatial dimension just not existing any more? I hope I don't sound like a crazy person.[/QUOTE] what well I mean I'm not as knowledgeable as JonnyMo ( so I may be inaccurate at points ) but that's just a crazy-speak theory. As much as any theory we can gather about a black hole. As mentioned in the video, for anything to escape a black hole ( or, be infinitesimally close to the event horizon, however time dilation is gonna fuck you up if you do that ) you must have a velocity greater than C. What this also implies is that no information can ever be extracted from a black hole. Any form of information travels at or below C ( hence from this you get length contraction and such when approaching V ~= C ). Unless we somehow manage to invent some form of FTL, and then manage to sustain that in insurmountable pressure, there is no way we can ever find out what is inside a black hole. Sure, we can gather what the makeup of stars and such are without travelling to them by their emission spectra; however as the name of a black hole suggests, the only thing being emitted by a black hole is Hawking radiation ( of which is still a theory and hasn't been observed ) and that's still dummy information. TLDR It's impossible to ever find out what lies inside the event horizon. It's one of those things that we'll only ever be able to theorise what exists within. Same with "What's outside the universe"
[QUOTE=NixNax123;49327512]to know is only to think you know[/QUOTE] My life is a big fat lie
What are the "virtual particles" he mentions in empty space that spontaneously appear and neutralize eachother? Can someone elaborate more on that? And I'm not sure if he mentions this but if that is the true reason black holes shrink and die, wouldn't a larger black hole (with more surface area to have these coincidental events be divided by the event horizon) shrink at a faster rate than smaller black holes?
[QUOTE=Kylel999;49329643]What are the "virtual particles" he mentions in empty space that spontaneously appear and neutralize eachother? Can someone elaborate more on that? And I'm not sure if he mentions that but if that is the true reason black holes shrink and die, wouldn't a larger star (with more surface area to have these coincidental events be divided by the event horizon) shrink at a faster rate than smaller black holes?[/QUOTE] The very loose heuristic way to think about it is in terms of the time-energy uncertainty principle. This says that the product of the uncertainty in the energy and the uncertainty in the time of a process must be above a certain value. So processes that happen in very small amounts of time (small time uncertainty) must have a large uncertainty in energy to compensate, and as long as a particle-antiparticle pair doesn't exist very long before annihilating, they can essentially "borrow energy" from the vacuum. Certain processes can separate these pairs before they annihilate.
I always thought since the way Black Holes are explained, that they have a very misleading name, since they are not actually holes but just massive amounts of mass in a small space. The only way they could be seen as holes is if the theory of a black hole in space time is like having a bowling ball on a mattress. Still not exactly a 'hole' but makes a dip in the fabric of what we know as reality. Also in a thousand years people of that time will look back at what we think we know about the universe the same way we look at people who thought the world was flat or that the sun rotated around the Earth
Are the virtual particles mentioned in this video related to the zero point energy field?
[QUOTE=NixNax123;49327512]to know is only to think you know[/QUOTE] Knowing is only the beginning
[QUOTE=RudeMcRude;49330523]I always thought since the way Black Holes are explained, that they have a very misleading name, since they are not actually holes but just massive amounts of mass in a small space. The only way they could be seen as holes is if the theory of a black hole in space time is like having a bowling ball on a mattress. Still not exactly a 'hole' but makes a dip in the fabric of what we know as reality. Also in a thousand years people of that time will look back at what we think we know about the universe the same way we look at people who thought the world was flat or that the sun rotated around the Earth[/QUOTE] There are ways to see them as holes. The singularity is a hole in the sense that it's no longer part of spacetime anymore. The black hole is a hole in the sense that it's no longer causally connected to the rest of the universe. [QUOTE=ZombieWaffle;49332145]Are the virtual particles mentioned in this video related to the zero point energy field?[/QUOTE] The "zero point energy field" is just word salad essentially. But no, they're pretty much unrelated to zero-point energy. Zero-point energy is nothing mystical. It just means that when you calculate the lowest possible energy of a quantum mechanical system, you might not get zero. But this doesn't change anything, because the only thing that's measurable is energy [I]differences[/I]. The only context where that isn't true is maybe quantum gravity, but we don't know how that works yet.
Is what he said about black holes not sucking anything in true? I guess it's just a super common misconception but I always thought the gravitational pull was insane. Like if you suddenly put a black hole here on earth it would eventually pull in the solar system.
Zero point energy is just the H.U.P isn't it; doesn't that technically mean that there can't be an absolute zero temperature then because of [t]https://latex.codecogs.com/png.latex?\Delta x \Delta p \geq \frac{\hbar}{2}[/t]? just confirming
[QUOTE=Dirf;49332948]Is what he said about black holes not sucking anything in true?[/QUOTE] If you're referring to him stating that if a black hole the mass of our sun replaced our sun that it wouldn't just suck in everything, then sure. But that's because it would be equivalent in mass, meaning that gravity would be functionally similar. However if a blackhole the SIZE of our sun replaced our sun, well, we wouldn't be here to discuss it. Gravity works similarly regardless of what you are, the difference between blackholes and stars is that black holes are TINY compared to their relative mass. mass is not equivalent to size.
[QUOTE=Dirf;49332948]Is what he said about black holes not sucking anything in true? I guess it's just a super common misconception but I always thought the gravitational pull was insane. Like if you suddenly put a black hole here on earth it would eventually pull in the solar system.[/QUOTE] If any celestial body was replaced with a black hole of equivalent mass nothing would change. Everything would orbit each other as normal and there would be no suction.
so does the heat-death of the universe make another universe-creating big-bang?
[QUOTE=comet1337;49336115]so does the heat-death of the universe make another universe-creating big-bang?[/QUOTE] Most likely no. In fact, there's a Kurzgesagt about exactly that: [media]https://www.youtube.com/watch?v=4_aOIA-vyBo[/media]
[QUOTE=Dirf;49332948]Is what he said about black holes not sucking anything in true? I guess it's just a super common misconception but I always thought the gravitational pull was insane. Like if you suddenly put a black hole here on earth it would eventually pull in the solar system.[/QUOTE] Other guy mentioned it, but you've got to consider how orbits work. The only reason we aren't sucked into the sun is because we have enough velocity to "constantly fall" away from the sun. If we were stationary, We'd be pulled straight into the sun. Same thing applies to a black hole, as long as you have the correct velocity you can easily maintain a stable orbit. Gravity works the sane regardless of source
[QUOTE=Instant Mix;49337695]Other guy mentioned it, but you've got to consider how orbits work. The only reason we aren't sucked into the sun is because we have enough velocity to "constantly fall" away from the sun. If we were stationary, We'd be pulled straight into the sun. Same thing applies to a black hole, as long as you have the correct velocity you can easily maintain a stable orbit. Gravity works the sane regardless of source[/QUOTE] Here's another way to think about it: Imagine you've got a binary star system, with a star of mass M and a star of mass m in a pretty close orbit around a common center of mass. If you're looking at this from far away, the gravitational field of this just looks like the gravitational field from a single star of mass M + m. If you're too far away to see the distance between the stars, you might think it was just one object instead. If the "internal distances" of the system you're considering are significantly smaller than the distance away that you're looking from, you can treat the system like it's just a point. Similarly, we're fairly far from the sun. Small variations in the gravitational field from small changes in density in different parts of the sun don't change our daily lives much. They're not strong enough to notice. For this reason, if the sun was a little bigger but the same mass, we may not even notice. If it was half the size and the same mass, we probably wouldn't notice. The sun may as well be a point, so when you have a super dense black hole of the same mass as the sun where the sun used to be, it doesn't affect us noticeably. What it definitely [I]does[/I] affect is surface gravity. If there was a black hole the mass of the Earth, the strength of gravity near the event horizon would be [I]much[/I] stronger than what we feel on the surface of the Earth, for the simple reason that you can get much closer to the center of mass. So in that sense, the gravity can be stronger. At a distance of Earth's radius from the center of the black hole, though, we expect the gravitational pull to be about the same strength.
[QUOTE=JohnnyMo1;49329684]The very loose heuristic way to think about it is in terms of the time-energy uncertainty principle. This says that the product of the uncertainty in the energy and the uncertainty in the time of a process must be above a certain value. So processes that happen in very small amounts of time (small time uncertainty) must have a large uncertainty in energy to compensate, and as long as a particle-antiparticle pair doesn't exist very long before annihilating, they can essentially "borrow energy" from the vacuum. Certain processes can separate these pairs before they annihilate.[/QUOTE] So wait, does this mean that the Big Bang is still sort of going on? From my limited knowledge of the Big Bang theory the idea is that a bunch of particles and antiparticles neutralized each other so quickly that it created an explosion and thus a metaphorical "Bang".
[QUOTE=TornadoAP;49341474]So wait, does this mean that the Big Bang is still sort of going on? From what I know of the Big Bang theory the idea is that a bunch of particles and antiparticles neutralized each other so quickly that it created an explosion and thus a metaphorical "Bang".[/QUOTE] We have basically no idea what caused the Big Bang. Our theories don't work before about a Planck time after the Big Bang. We need a theory of quantum gravity to predict that. I've never heard that idea, that matter-antimatter annihilation caused the Big Bang. Are you sure you didn't misunderstand? There is an interesting question of what happened after the Big Bang for there to be so much more matter than antimatter in the universe since we expect them to show up in equal amounts.
Sorry, you need to Log In to post a reply to this thread.