10 FACTS ABOUT BLACK HOLES

The mystery of black holes solved here…

1. A Black Hole is usually a collapsed star

Many scientists believe that a black hole is formed when a star runs out of fuel and burns out. The star cannot maintain its’ high temperature and the pressure pushing outwards decreases as a result. The huge gravitation pull, characteristic of black holes, exceeds this pressure and the star implodes or collapses.

What remains is what is known as a Black Hole. It has been coined a ‘black’ hole as all light is absorbed and none is reflected.

2. There’s no escaping

The gravity is so strong that the velocity that would be needed to escape the black hole is greater than the speed of light. Nothing can travel faster than the speed of light at ~ 3 x 10^8 m/s – not even Usain Bolt. If nothing can travel faster than the speed of light, then nothing, and I mean nothing can escape!

3. Large Mass Small Space

The star has been crushed by its own gravitational weight. There is a large mass in a very small area.

To give you some scale:

If trying to form a Black Hole with the same mass as Earth, it’s like trying to squeeze the mass of the Earth into the space between your finger and thumb, where your pen may rest.

If trying to form a Black Hole with the same mass as the Sun (significantly bigger than the Earth), you would need to compress the Sun into the size of Sheffield.

That’s a whole lot of ‘stuff’ in not very much space!

4. Seeing is believing

Are Black Holes for real?

You can’t actually see a black hole directly (not even light can escape, it’s just darkness) so how do we know they exist?

What is usually illustrated are bright lights and visually stimulating images. The picture would be pretty boring if we didn’t show these.

The bright lights are nearby stars that orbit the Black Hole due to its strong gravitational pull. They can be used to determine the black holes mass and location. So orbiting stars provide a strong indication that there is a black hole.

Something called an ‘accretion disc’ can form as seen in image 1. The gravity pulls surrounding material including stars in a spiral inwards towards the Black Holes centre, producing some of the brightest objects in the Universe and this is what can be seen!

Black Holes also emit radiation (typically high energy particles), this can be measured by scientists.

All of which provide evidence for the existence of what we have come to call a black hole!

There is believed to be a black hole at the centre of our galaxy.

5. The Event Horizon

The Event Horizon is the boundary to a Black Hole.

Imagine you’re at the top of a fast flowing waterfall, frantically rowing against the current so not to be swept down, down, down…

The current is too strong and you are swept over the edge, there is no going back.

For a black hole this point or boundary is known as the Event Horizon – commonly described as the point of no return. It is the strong gravitational pull in the case of a black hole not the fast flowing waters that means there is no going back.

6. The point of no return

So once you’re in, you’re in. The gravitational force is so great nothing can escape. If you were to see an object approaching the event horizon, it would seem to slow down but never quite pass the horizon.

However, the object does in fact pass through into the black hole.

How can two opposing things be witnessed?

The strong gravitational force distorts what is seen. If you are a long way away you don’t see the object pass the event horizon. However, in reality the object does pass across. Everything is relative so you see different things depending on where you are.

7. Life inside a Black Hole

So what’s it like in a black hole? Well no one is exactly sure as no one has been in and out to report back (the whole nothing can travel faster than light thing). It truly is a mysterious Black Hole.

At the centre of a black hole there is a mysterious thing called ‘singularity’. No one completely understands it, it has scientists baffled as here the Laws of Physics which Scientists have come to accept break down.

What we do know is if an object were to reach singularity it would be crushed to infinite density and its mass would be added to the total mass of the black hole.

8. Spaghettification

If an astronaut were to find him or herself in a Black Hole, before singularity, it is thought that they would be torn apart in a process called Spaghettification or the Noodle Effect.

Spaghettification is the vertical stretching and horizontal squashing of an object into a long thin shape – a spaghetti-like shape, the result of a strong gravitational field.

As we have discovered Black holes have this strong gravitational field, no object nor astronaut could withstand it --> SPAGHETTIFICATION !!

9. BOOOOM

Black holes emit thermal quantum radiation and the temperature of a Black Hole is proportional to 1/ (black hole mass):

T≡ 1/M

So a Black hole emits radiation --> the black hole shrinks --> from the equation the black hole must get hotter --> more radiation is emitted --> again temperature must increase…and so on…--> EXPLOSION

Until the Black Hole explodes

10. The End of the World is Nigh?

The Large Hadron Collider (LHC) at CERN, is an experiment where scientists are trying to create mini black holes.

So why are experiments of this nature important?

High energy particles are collided and what happens/ what can be seen is measured and observed. This is done to help explain and validate the fundamental Laws of Physics which underpin all matter and energy in the Universe. Providing further verification for why things are the way they are.

So what exactly is the point of this?

An analogy using the Big Bang, theory of how the Universe began, is often used. Currently space is huge and cold, however, if you were to go back in time to when the Universe began, it was much smaller and hotter. At the LHC they are recreating similar conditions from the energy produced by the particle collisions.

If black holes were created at the LHC, it could provide evidence in support of the Big Bang as it could explain how something (the Universe) started off so small (very small particles) and hot and how it came to be so huge. Remember Black Holes are a large mass in a small space.

Despite a lot of media attention, if black holes were created at the LHC, the world would not end. Many had suggested that the black holes had the potential to swallow the Earth.

More recently, Stephen Hawking has claimed that Black Holes may not exist exactly how scientists believe them to be. This could change all that is known about black holes...http://www.youtube.com/watch?v=gBTzKpJ9BRg

The Universe remains a fascinating and mysterious place.