Home, Science, Science Concepts

Nuclear Fusion- Does Our Future Depend On It?

Hi Guys,

I’m sorry for the long pauses in between posts, I’m busy with my third year in secondary school and I simply do not have as much time to write these posts anymore. This year i will be participating in a lot more activities (Science Mentorship Programme, completing my novel etc.). Blogging has been really fun and i really wish that i can make time to do more of these blogs. However, it’s really tough to pull myself to blog after a long day at school. Furthermore i try to make my posts as good as possible and this makes blogging take even more time. In fact i have been working on this very post since mid-December. I will definitely continue to post more, but the frequency of posts will have to be reduced. I simply can’t bring myself to post something that I myself feel is of low quality.

Okay, enough talk, lets get back to the main topic of this post.

I have been thinking about fusion lately after watching a TED video regarding the issue. Fusion has always been something extremely fascinating to me ever since I learnt about it. (and yes, I am going to keep referring to nuclear fusion as fusion.)

When we, as a human race, try to solve engineering problems, we usually turn to nature to give us inspiration. From the minesweeper inspiring tumbleweed to lotus leaves that have inspired us to create hydrophobic surfaces, nature has helped us solve our issues again and again. Fusion is one of those instances where we have taken inspiration from nature, but this time instead of seeking that inspiration from living beings on earth, we have taken that inspiration from the skies.

When we gaze into the sky at night we see stars, hundreds, thousands, even millions of them. When we look into the sky in the day, we see the sun. All these majestic things that fill the sky are all powered by nuclear fusion, the very thing we seek to be able to utilise some day. The intense light and heat coming from the sun and the stars are all produced by tiny nuclei colliding into each other; resulting in part of their mass being converted into energy.

The amount of energy produced is insanely huge. How huge? To answer this question we must look at one of the most famous equations in human history. E=mc^2. E equals m c squared. The energy-mass equivalence formula. Whatever you call it. Developed by the famous Albert Einstein, this short equation reveals the power of nuclear power. Here are the definitions of the terms in the formula:

E- Energy

m- Mass

c- the speed of light

Well if you consider the fact that the speed of light is 300,000,000 m/s (or 300 million m/s) )and after squaring the value you get 90,000,000,000,000,000 (or 90 trillion), you can convert 1 kilogram of mass into enough energy to keep the entire world running for 6 seconds. Well, that ain’t bad considering we burn 9,825,414,830 liters of oil in a day. That’s over 9 billion liters of oil and oil only.

So yes, fusion is powerful. Very powerful. So how does it work? In the stars, intense heat and pressure (and sometimes with a bit of luck), fusion occurs. The heat causes the atoms in the stars to move extremely quickly, this causes the atoms to collide into each other very frequently and with extreme speed and force. The pressure forces them closer to each other, further increasing the frequency of the collisions. With these ingredients, together with some nuclear fuel, the beautiful process occurs, generating large amounts of heat (the energy that is released from the process). PhdComics has made a video explaining the process of fusion.

Fusion makes use of nuclear fuel with small nuclei such as hydrogen and helium. The process can only fuse atoms up to iron. Atoms larger than iron are too heavy to be fused any further. This is opposite of nuclear fission where nuclear fuel with large nuclei are used. After iron, to produce larger nuclei, a supernova has to occur for heavier elements to form.

I recently found this joke on the website SGAG. To those Singaporeans out there, you should probably understand this joke:

fusion joke

 

The above is in fact true! The reason why supernovas are able to allow larger atoms to form is due to the fact that the force of the explosion generated by the supernova is so great that the iron actually manages to fuse into larger nuclei. Through the explosions of millions or even billions of supernovas, the atoms essential for life were formed.

You could say that you were born from a dying star 🙂

“The most astounding fact is the knowledge that the atoms that comprise life on Earth, the atoms that make up the human body, are traceable to the crucibles that cooked light elements into heavy elements in their core under extreme temperatures and pressures.

These stars, the high mass ones among them went unstable in their later years. They collapsed and then exploded, scattering their enriched guts across the galaxy. Guts made of Carbon, Nitrogen, Oxygen and all the fundamental ingredients of life itself. These ingredients become part of gas clouds that condense, collapse, form the next generation of solar systems, stars with orbiting planets, and those planets now have the ingredients for life itself.

So when I look up at the night sky and I know that yes we are a part of this universe, we are in this universe, but perhaps more important than both of those facts is that the universe is in us, when I reflect on that fact, I look up, many people feel small cause they’re small and the universe is big, but I feel big because my atoms came from those stars. There’s a level of connectivity.”

Neil deGrasse Tyson (in a TIME magazine interview)

Essentially, why I study physics.

 

Our current nuclear power plants utilise nuclear fission. The reason for this is due to the fact that fusion is extremely difficult to produce in comparison to fission. Nuclear fission occurs naturally. If you left a block of uranium somewhere, it would literally begin to decay and release energy as heat. However if you leave hydrogen gas alone, it would most definitely not fuse to produce helium.

Stars can make fusion happen relatively easily; they can use their gravitational force to create the high pressures and their already present heat as heat to sustain the fusion. However, the Earth is nowhere near as large or as heavy as a star. To make fusion happen, we utilize multiple methods.

I shall discuss these methods in a future post. I’m sorry i have to cut the post here but i have been delaying this post by a very long time. I hope to release part 2 soon XD.

Regards,

Clyde Lhui 🙂

 

P.s I’m still working on a lot of other posts at the same time, these posts will probably take quite a while to complete. Do tell me if you have any suggestions for new blog posts.

Advertisements
Home, Science, Science Concepts

Black Holes- Part 1

Hi guys,

New guy here 😀 . I’m Jackson and you would have known me by now after being mentioned in some of the previous posts. However, if you are new to this blog, I am Clyde’s classmate and often discusses Science topics with Clyde. And yes, I am also the new admin here. As I am new here, I will start with an easy topic that requires not much concept          — just fun facts and no Math at all– unlike the mind-boggling Special Relativity that Clyde is doing. Without further ado, let’s jump into one of the most interesting topic, ‘Black Holes’.

Okay, so What is a Black Hole? 

Just from the name itself, most of you would have guessed a hole, a tear in a paper, a pit in the ground. In fact, it is a hole in space time itself, a hole where time slows down so much that you will eventually reach a point where it stops, a hole with an attraction so great that not even light, the fastest thing in the universe can escape. It is an area in the universe where if you drop into…… whoosh, you will disappear, cease to exist, voided from the rest of the world. Sounds dreadful eh? The idea of Black Holes started of as just an abstract concept that was not supported by any evidence and not many scientist believed it exist. Only in 1931, when an astronomer by the name of Chandrasekhar calculated and gave mathematical evidence of potential high mass stars that could form Black Holes, did scientist started paying attention to it.

Even until this day, no scientist has truely understood this mysterious entity, all the laws of physics break down at the singularity of a Black Hole and since no information can escape, there is no way to observe the events at the singularity.

Let’s look at the science of a Black Hole.

Formation of a Black Hole

Imagine an object that is constantly being compressed, its volume will decrease while its mass remains the same, this causes the object’s density to increase as, desity = mass/volume, the mass is a constant hence, a lower volume divided would cause a higher density. An increase in density would also cause the object’s surface gravity increase. As the object is compressed, the object will eventually reach a size where it would have a surface gravity so great that not even light can escape, this is known as the  Schwarzschild Radius. At this point, the object would no longer be able to hold against its own gravity and would collapse infinitely into a point in spacetime known as the singularity, forming a black hole.

However, compressing an object into its Schwarzchild Radius and making a self sustaining Black Hole with brute force is unrealistic and is immensely difficult (so don’t even think about squeezing your golfball into a star hungry galatic black hole of mass destruction to take over the human race). In fact, you will need the power of the stars.

Stars are fueled by nuclear fusion. The proccess of nuclear fusion is basically the combination of two atomic nuclei, releasing the binding energy within the atom. In this proccess, the total mass of the two nucleus decrases, as they are being converted into energy, hence proving the mass energy equivalence. You can find out how much energy is released by finding the change in mass of the atoms and multiplying it with the speed of light squared (3×10^8^2). As the speed of light is HUGE, the energy released, which uses the square of the speed of light, would be unimaginable.
Let’s get back to point, the stars in the universe all start out with one element, Hydrogen. These Hydrogen atoms undergo nuclear fusion and fuses together to form Helium. Helium would then continue fusing to form Carbon, Oxygen and so on. As fusion occurs in a star, energy would be given out as radiation. The radiation would be causing the outward force that prevents the star from collapsing into itself. Usually, an averaged sized star would not have enough energy to continue nuclear fusion after all the carbon has fused to form oxygen, they would cool down into a white dwarf. However, a star that is much more massive would continue the fusion proccess all the way until iron atoms are formed. As iron atoms can no longer fuse, the proccess stops. By then, so much pressure would have built up from the outward force the star is exerting against its own gravity to balance out. Once the fusion proccess stops and the star no longer emits radiation, the gravitational force would suddenly overwhelm the star’s outward force, and in a short period of time, all the matter rushes inwards to the center of the star.

This would be followed by an explosion known as supernova or sometimes even more powerful explosions known as hypernova. After that, the collapse would either stop, forming a neutron star (the densest and smallest stars known to exist in the universe, it is so compressed that all the electron have the energy state to combine with protons to form neutrons, in a proccess known as inverse Beta Decay) or have high enough mass to continue collapsing into a singularity, creating a black hole.

There is another way in which Black Holes can form from the collision of two neutron stars but I will not go into detail on that.

Thanks,
Tiong Jackson :p