Let’s take a look into the mysterious and mind-boggling world of black holes. What are they, and how do they form. And can they really bend time itself?
The idea of an object in space so massive and dense that light could not escape it has been around for centuries. Most famously, black holes were predicted by Einstein’s theory of general relativity, which showed that when a massive star dies, it leaves behind a small, dense remnant core.
If the core’s mass is more than about three times the mass of the Sun, the force of gravity overwhelms all other forces and produces a black hole.
Black Hole Formation
Most black holes form from the remnants of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to trap light.)
If the total mass of the star is large enough (about three times the mass of the Sun), then the star will collapse under the influence of gravity.
However, as the star collapses, a strange thing occurs. As the surface of the star nears an imaginary surface called the “event horizon,” time on the star slows relative to the time kept by observers far away.
When the surface reaches the event horizon, time stands still, and the star can collapse no more – it is a frozen collapsing object.
The collapse is so intense that it squeezes all the star’s mass into an incredibly tiny space, creating what we call a singularity.
A black hole is incredibly dense and has a pull of gravity so strong that not even light can escape it.
Scientists can’t directly observe black holes with telescopes that detect x-rays, light, or other forms of electromagnetic radiation. We can, however, infer the presence of black holes and study them by detecting their effect on other matter nearby.
If a black hole passes through a cloud of interstellar matter, for example, it will draw matter inward in a process known as accretion. A similar process can occur if a normal star passes close to a black hole. In this case, the black hole can tear the star apart as it pulls it toward itself.
As the attracted matter accelerates and heats up, it emits x-rays that radiate into space. Black holes come in different sizes. We have stellar black holes, which are a few times more massive than our Sun, and then there are supermassive black holes, millions or even billions of times more massive, which lurk at the centre of galaxies.
Scientists have very recently captured this image, of a supermassive black hole at the centre of our milky way galaxy.
Time Dilation
Another thing to consider is time dilation. Imagine you’re near a black hole, time would actually slow down for you compared to someone farther away. It’s like a cosmic time machine!
So, if we could travel near one, and you could spend a nice day on a spaceship near a black hole, years could be passing by in a flash for us back on earth. It’s like a sci-fi plot twist right in the fabric of space-time! Go see the movie interstellar for more on that!
We’re only just beginning to scratch the surface on how black holes work. There’s still so much about them that we don’t quite yet understand. But scientists are working on it!
The post What is a Black Hole? appeared first on Danny Nics Science Fix. Written by Danny Nicholson