20.2.10

Censor the Stars


I love astronomy. It has been one of my fascination domains for a long time and learning about it or simply staring into the night as the light stops to conceal what's beyond has always given me that state of insignifiance that sometimes feels so good.

I recently re-re-re-rewatched a documentary on supernovas and black holes. Black holes, now that's a force that I'd be glad to wield. Although I have been a failure in physics, I always enjoyed this side of dynamics. I was always enticed by black bodies, but black holes are my first love.


Just by reading these, I get shivers:


"Now imagine an object with such an enormous concentration of mass in such a small radius that its escape velocity was greater than the velocity of light. Then, since nothing can go faster than light, nothing can escape the object's gravitational field. Even a beam of light would be pulled back by gravity and would be unable to escape. [...] Near a black hole, this distortion of space is extremely severe and causes black holes to have some very strange properties. In particular, a black hole has something called an 'event horizon.' This is a spherical surface that marks the boundary of the black hole. You can pass in through the horizon, but you can't get back out. In fact, once you've crossed the horizon, you're doomed to move inexorably closer and closer to the 'singularity' at the center of the black hole. The horizon has some very strange geometrical properties. To an observer who is sitting still somewhere far away from the black hole, the horizon seems to be a nice, static, unmoving spherical surface. But once you get close to the horizon, you realize that it has a very large velocity. In fact, it is moving outward at the speed of light! That explains why it is easy to cross the horizon in the inward direction, but impossible to get back out. Since the horizon is moving out at the speed of light, in order to escape back across it, you would have to travel faster than light. You can't go faster than light, and so you can't escape from the black hole. Trying to avoid the center of a black hole once you've crossed the horizon is just like trying to avoid next Thursday. "


But this is the best part and it's a journey I often find myself in, when I dream about it:


"Let's suppose that you get into your spaceship and point it straight towards the million-solar-mass black hole in the center of our galaxy. (Actually, there's some debate about whether our galaxy contains a central black hole, but let's assume it does for the moment.) Starting from a long way away from the black hole, you just turn off your rockets and coast in. What happens?


At first, you don't feel any gravitational forces at all. Since you're in free fall, every part of your body and your spaceship is being pulled in the same way, and so you feel weightless. (This is exactly the same thing that happens to astronauts in Earth orbit: even though both astronauts and space shuttle are being pulled by the Earth's gravity, they don't feel any gravitational force because everything is being pulled in exactly the same way.) As you get closer and closer to the center of the hole, though, you start to feel "tidal" gravitational forces. Imagine that your feet are closer to the center than your head. The gravitational pull gets stronger as you get closer to the center of the hole, so your feet feel a stronger pull than your head does. As a result you feel "stretched." (This force is called a tidal force because it is exactly like the forces that cause tides on earth.) These tidal forces get more and more intense as you get closer to the center, and eventually they will rip you apart.


What do you see as you are falling in? Surprisingly, you don't necessarily see anything particularly interesting. Images of faraway objects may be distorted in strange ways, since the black hole's gravity bends light, but that's about it. In particular, nothing special happens at the moment when you cross the horizon. Even after you've crossed the horizon, you can still see things on the outside: after all, the light from the things on the outside can still reach you. No one on the outside can see you, of course, since the light from you can't escape past the horizon.


Once you've crossed the horizon, in your remaining seven seconds, you might panic and start to fire your rockets in a desperate attempt to avoid the singularity. Unfortunately, it's hopeless, since the singularity lies in your future, and there's no way to avoid your future. In fact, the harder you fire your rockets, the sooner you hit the singularity. It's best just to sit back and enjoy the ride. "


You don't have to read all this, I mostly put this for my own amusement.



But what I have found myself in was a massive star explosion that would've emitted billions of little small stars, flying like a tress of shooting stars, all yellow. Humans had the ability to see this before it happened and they decided that when the event will occur, they will censor it because people weren't ready to view such a spectacle. I was in an abandoned NASA warehouse, trying to figure out a way in which I could stop this censor and let people see the "real deal". That was a dream..a beautiful one. How could people think of censoring the stars?..

2 comments:

Michael said...

It's nice to see that I share passions with other people :)

Even though I never had the occasion to study the physics behind astronomy, I just love to watch documentaries about the Universe... It looks like we could talk for hours regarding this subject.

I could recommend some titles which are worth watching. Did you ever hear of Carl Sagan? :)

the elder said...

Exactly. And yes, I've heard of C. Sagan, he's one of the few people I respect in this subject, for allowing the thought of alien life. :D