![]() ![]() As she approaches the edge of the black hole, something strange happens, and this is where Einstein rears his head again. So let’s say her friend Bob gives her a push and she starts to ride the spiralling density waves in the disk. Unless her surfboard is rocket powered, it could take weeks or even years to reach the black hole. So Alice parks her spaceship just outside the edge of the accretion disk, jumps on her surf board and away she goes! Well no, not really. We could see that they were much smaller than galaxies but we could also see that they were some of the brightest yet most distant objects in the Universe, so how could something so small produce so much energy? Well now we know and it just shows how much energy there is in these jets. This is short for “quasi stellar object” and when planet Earth and I were young, way back in the 1970’s, we didn’t know what these were. In the case of a supermassive black hole at the heart of a galaxy, if a jet is pointing at us we call it a Quasar. So Alice’s space suit and surf board need to be highly heat resistant or it will be a very short ride! By the way, as the hot glowing matter reaches the black hole some of it gets shot out from the poles at near light speeds, forming jets that reach far out into space. Oddly enough, it is the smaller, stellar mass black holes whose accretion discs reach the highest temperatures for the simple reason that the smaller the black hole, the smaller the radius of the accretion disk so the closer the atoms in it get to each other. This creates friction and lots of it, and as we also know, friction creates heat and in the case of a black hole accretion disc temperatures can get extremely high. As all this stuff gets closer and moves faster, anything big gets pulled apart until there are just atoms left and these bump into each other as they hurtle round and round the black hole in ever decreasing circles. As we know, as something spins in a smaller and smaller radius, it rotates faster and faster and this is also true of all the stuff a black hole traps. As they get closer they start to spiral in, their orbit getting closer and closer. Its full of gas and dust floating around, and there are stars and even planets wandering around and sometimes these get too close to a black hole and get pulled in. This is kinda what that looks like-īut our Alice is no chicken, she wants the ultimate thrill and the ultimate selfie to post on her FB wall so she lets the black hole’s gravity pull her closer. So if Alice is a chicken, she’ll turn her spaceship around now, or just keep going straight ahead and fly past the black hole. ![]() At first all they feel is the gentle but insistent pull of gravity. So what happens to stuff that gets too close, you know stars, spaceships etc? Well not a lot really, until they get very close. Showed us, that ain’t allowed, so nothing, not even light gets out. So basically you’ve got the core of this dead star and this core has shrunk down to a size where its gravity, when you get close, is so concentrated that you would have to travel faster than light to get out, and as this guy Quite a simple sum for something as incredible as a black hole. You then divide by the speed of light multiplied by itself. You take the mass of the object you want to turn into a black hole, the Earth, a star, your boss, and multiply it by the “Gravitational Constant”, (a constant is just a number that gets a sum to work), and multiply the whole lot by 2. Anything can become a black hole in theory, you just have to compress it enough. As it collapses it reaches a point where its gravity is so concentrated, and that’s the word to remember, not “so great” or “so colossal”, just concentrated, that its escape velocity is higher than the speed of light. If the star is big enough then the core collapses down into a black hole. ![]() I’d like to come back to supernovae at a later date as there is a lot to talk about. Actually a black hole is nothing more than the mortal remains of a star, a star much bigger than our Sun, that blew itself apart in its spectacular death throes. A black hole is not some kind of voracious monster, intent on destroying everything around it. Here is her story.įirst off, what is and accretion disk? Well contrary to SciFi films and stories, black holes do not suck everything into them. ![]() Today we are going to look at what might happen to her great, great granddaughter if she got bored with the more normal extreme sports like bungee jumping, white water rafting and and free climbing, and decided to try a new extreme sport, Accretion Disk Surfing. There was once, according to the story, a little girl who fell down a rabbit hole and discovered a strange world where the normal physical rules of how our world works no longer applied. ![]()
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