Falling into a black hole?;a brief look into the science behind it!

If you fell into a black hole, would you enter a 5th dimension similar to what happened to Cooper in Christopher Nolan’s award winning film Interstellar?

Well to answer this, we have to understand what a black hole is. This article covers a brief overview on the science surrounding what a black hole is, its features, conditions of a black hole, what would happen and some prompts for further reading to gauge your interest on the topic!

So, what is a black hole?

A black hole is a region in spacetime where huge concentrations of matter are found. It has such an immense gravitational pull so intense that not even light can escape, hence the name black hole.

Picture link

The reason as to why its gravitational pull is so intense, is linked to the nature of black holes and how they are formed.

Note: I will only be going over the formation of stellar black holes to simplify why gravity is so intense. Please note there are 3 other types of black holes which I encourage you to look further into if interested.

A dive into the formation of black holes; why is there gravitational pull so intense?

One of the most commonly known types of black holes are stellar black holes. These are formed through the life cycle of stars that are usually approximately 8 to 10 times the size of our sun.

All stars (despite their sizes), are known to be stable due to the forces acting upon them being in equilibrium (equal) to one another. There are 2 main forces; the force of gravity which acts inwards & radiation pressure which acts outwards relative to the stars core.

Radiation pressure is released from the nuclear fusion that happens within the stars core. This fusion involves the joining of smaller light nuclei such as hydrogen to make heavier nuclei such as helium and many other heavier elements (up to iron) in the context of larger stars. This in turn emits radiation which exerts an outwards pressure onto the surrounding gas particles in its core which counteract the force of gravity.

How is radiation able to exert pressure?

This is because radiation which is a form of an electromagnetic wave, has momentum, so when light hits the surrounding gas particles it will undergo a change in momentum. As there has been a change in momentum in a given time, from a level physics, we know change in momentum/ time is equal to force. This force is acted upon a given area, the gas particles. If we have a force acting on an area this gives us a pressure. Hence why radiation pressure exists. A more in depth version can be found here:

Back to gravitational pulls intensity:

Whilst smaller stars similar to our suns collapse when their hydrogen run outs. Larger stars that form black holes, undergo nuclear fusion until they produce heavier elements up to iron. When majority of the core becomes this element, the inward pressure is not great enough to counteract the outwards force of gravity, triggering the star to collapse leading to supernova explosion.

Supernova picture link

After the supernova, what is left is a very dense core which can either be a neutron star or if dense enough, a black hole. As the density is so high in a black hole, this causes a great distortion in the spacetime which manifests as gravity. Meaning the bigger the object the greater the gravity according to einsteins equations on general relativity. Hence why the density of a black hole is very high.

So, as black holes have immense gravity, matter in space tends to gravitate towards it.

Features of a black hole?

Accretion disk -

This is the bright light that is seen to surround the black hole, this is composed of matter/gas that orbits the black hole at high speeds, the particles revolve around the black hole at fast speeds and compress causing them to glow.

Event horizon -

This is what makes a black hole appear black.The reason as to why this is, is because in order for any matter to escape, it needs to travel faster than the speed of light, as this is impossible to do within our universe, hence why once light gets in… it never gets out.

Singularity -

A point in space time where gravity is infinitely strong with all the black holes mass compressed into an infinitely small volume.

So, what would happen?

As we approach the black hole, time would seem to be travel at normal speeds.

As we get closer and closer to the event horizon, an outside observer would see us to be moving extremely slow, this is due to the effect spacetime has on gravity. From our perspective, your body would start to get longer and longer, if you were to move your head from side to side, you’d also be able to see parts of your body, due to the significance in gravity.

As you get closer to the singularity, a phenomenon called spaghettification would occur, where you inventually reach your death.

So, what do you think lies beyond the event horizon in a black hole?

Further reading/ Prompts

Whilst researching about black holes, I came across a lot of terms and interesting concepts, listed below are some prompts for your own research to learn more about this topic or field. Put these into your search engine and see what you find!

• What are the other types of black holes categorisations?

• What is the cosmological principle?

• What is the schwarzschild length?

• Sagittarius A* ; where is it & what is it?

Please also look at the sources below that were used as references to create this blog!

Sources:

(1) (2)(3)(4)(5)(6)(7)(8)(9)(10)