Student Projects

Independent-learning super-curriculum projects: reading, research and ideas shared by Perse students

Black Holes : Thomas C, Year 9

A Year 9 student wanted to find out some more about black holes and wormholes in his own time.

The birth of star

In space there are clouds of dust and gas and if one of the clouds is big enough it collapses in on itself and dust and gas start to stick together to create a star. Fusion occurs which powers the star. Different things happen to stars in their life time it just depends on how big the star is when it is created.
The death of stars
Smaller stars
Stars use hydrogen to keep alive but when it runs out the core of the star will collapse in on itself under its own weight. It then uses its helium atoms pushing them together to create carbon atoms and will continue to create heavier elements in the periodic table. The star will then expand due to the mass production of energy produced in the core. It’ll keep expanding becoming a red giant which is the beginning of its death. The force of gravity as it expands will get weaker and weaker until its atmosphere just expands dramatically this is known as a planetary nebular. In the centre of this planetary nebular is a dwarf star a corps of a once bright star. After millions of years this dwarf star will eventually cool down to become a black dwarf.
Bigger stars
When a bigger star collapses it is able to fuse far heavier atoms then smaller stars. The star keeps expanding until it has fused elements all the way to iron. After an iron core has been created no more energy can be created and so the core and the rest of the star collapse in on themselves. Until a huge shockwave occurs and the outer layers of the star are blasted far into space this is known as a super nova explosion, super nova’s can be so bright they can out shine whole galaxies. All that is left after the explosion is an incredibly dense core known as a neutron star. But for the biggest stars scientists think that the gravity becomes too strong and the star becomes a black hole.

Black holes

How Black holes are created
Anything can become a black hole if you compress it down to a small enough space. This is known as a Schwarzschild radius. This is how far you would have to collapse an object down to a small enough density that its gravitational pull would be so great that not even light could escape from it. Larger objects have a larger Schwarzschild radius, so a star when it runs out of energy collapses in on itself to an infinitely small point which is what’s known as a singularity.

Looking at black holes
Black holes bend and distort light so if you tried to look at a galaxy but it had a black hole in front of it, it would look distorted. This is known as gravitational lensing. It may look like the galaxy has been ripped apart but it hasn’t it’s just the light coming off of the galaxy has been moved around making it look distorted.
If you were to approach a black hole the distortion of space becomes greater and greater, a larger portion of your view will be of the black hole but when half of your view is just darkness you would have reached the photon sphere. This is a point of the black hole where light doesn’t get sucked into the black hole but it doesn’t escape it either. The light orbits the black hole. So theoretically you could look to your left and see the back of your own head, as the light coming from the back of your head orbits all the way round the black hole until you can see it with your eyes.
As you get even closer to a black hole your approach would become slower and slower until you reach the event horizon. This is the point of no return. As you get further and further into the black hole the parts of your body closer to the singularity would be pulled more than parts of your body facing away this effect is known as tidal force. So your body would be stretched dramatically. This is known scientifically as spaghettification; at this point you would be dead.

Spinning black holes scientists think might be wormholes. Wormholes are a means of travel so you can get to places faster than the speed of light but not in any way that violates the laws of physics it just takes advantage of space dimensions.


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