Falling into a black hole; A brief look into the physics behind it!

Michelle Ncube
Aug 8, 2025
5 min read

Updated: Oct 3, 2025

If you fell into a black hole, would you eventually find yourself in a tesseract similar to what happened to Cooper in Christopher Nolan’s award winning film Interstellar?

This is one of the questions I had when watching Interstellar whilst laying down on my bed, enjoying the comfort of my blanket. Battling the seasonal flu I had is a memory I’ll cherish as it made the movie feel more influential.

To understand whether Interstellars depiction has any basis in the physics that govern our world, we first need to explore what black holes are, their formation and what would theoretically occur if we “fell” into a black hole.

What is a black hole?

A black hole is a region in spacetime where matter has collapsed into an extremely dense point. This causes an immense gravitational pull so intense that not even light can escape making it appear black, hence why it’s called black hole.

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The reason as to why its gravitational pull is so intense is linked to how black holes are formed.

Note: I will only be going over the formation of stellar black holes.Please note there are 3 other types of black holes, which you can research into yourself!

A dive into the formation of black holes

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

All stars (despite their masses), are considered to be stable due to the forces acting upon them being in equilibrium (equal to one another).

There are 2 main forces that act on a star. One of which is the force of gravity which acts inwards & radiation pressure which acts outwards, both 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 two smaller light nuclei such as hydrogen to make heavier nucleus such as helium and many other heavier elements (up to iron) in the context of larger stars.

This in turn emits radiation in the form of light which exerts pressure onto the surrounding gas particles in the stars core that counteract the force of gravity.

Dive : How is radiation able to exert pressure?

Radiation is a form of an electromagnetic wave, it 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, this exerts a force which is acted upon a given area (the gas particles) meaning pressure is being exerted. Hence why radiation pressure exists. A really good mathematical explanation can be found here:

Back to the formation of black holes..

Whilst smaller stars similar to our suns collapse when their hydrogen runs out. 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 outward pressure is not great enough to counteract the inward pull of gravity, triggering the star to collapse. This leads to supernova explosion.

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After the explosion, what is left is a very dense core which can either be a neutron star or if dense enough, a black hole. As the mass and density is so high in a black hole, this causes a great distortion in the spacetime which manifests as an immense gravitational pull.

Some features of a black hole

Having some knowledge about the structure of a black hole is also essential to be able to know what would happen. Below are three features if a black hole in order from the outside to inside of a black hole.

Accretion disk

This is the bright light that is seen to surround the black hole. It’s composed of matter/gas that orbits the black hole at high speeds. This causes the particles to compress causing them to emit light, leading to that visible glow we see in black hole pictures. In reality however, the accretion disk wouldn’t actually appear to emit white light to the human eye. The part of the black hole rotating towards us would appear more blue and brighter whilst the other side rotating away from us would appear more redder and dimmer.

Event horizon

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

Singularity

This is the centre of the black hole where gravity is considered to be infinitely strong as all the black holes mass compressed into an infinitely small point. According to Einstein’s theory’s of general relativity a singularity is predicted to exist at the centre of every black hole.

So, if you fell into a black hole what would happen ?

As you approach the black hole, time would seem to pass normal from your perspective. However, to an observer watching from a distance, your motion would look as if it’s slowing down as you get closer to the event horizon due to gravitational time dilation.

As you’re about to cross the event horizon, the light reflected from you would take longer to reach distant observers so they would see you fade and slow down even more, to the point where you are not moving at all, even though you still are in your perspective. This is because the light becomes red shifted so as if goes from visible to infrared then radio, as we can’t see that spectrum it becomes invisible.

As the black holes we are looking at are stellar mass black holes, you’d experience spaghettification due to tidal forces being so strong. The gravitational force on your feet compared to your head would differ greatly, therefore you’d stretch just like a spaghetti!

This would usually happen before reaching the event horizon but for larger black holes this may only happen after you’ve passed it.

Moving on.. after passing the event horizon you will never be able to escape the black hole as you’d need to travel faster than the speed of light which is our universal limit of speed. You would only fall further and further towards the singularity where gravity is deemed to be infinite.

But does this mean you would enter a tesseract like cooper?

In interstellar, Cooper is seen to fall into the black hole Gargantua and ends up inside the tesseract which is a 3D representation of a 5D space. It is known that ths idea was developed with guidance from a theoretical physicist Kip Thorne, who was the scientific consultant and executive producer for this movie. Therefore, this could allude to the fact that there could be some truth in eventually entering a tesseract after falling into a black hole.

HOWEVER, what would happen after reaching the singularity is actually not known due to a lack of scientific evidence. The laws of physics are said to break down at a black holes singularity due to its infinite amount of gravity so we may not ever have a way of actually knowing what would happen as this is still up to speculation .

So probably not, although it is an interesting idea based more on imagination rather than science.

What do you think would happen?

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 field.

Put these into your search engine and see what you find!