Quantum Physics

Physics can be separated into three main groups. The physics which explores the motion of everyday phenomena, theorised primarily by Newton, the physics which explores space and the grand schemes of things, which is theorised primarily by Einstein; and finally, quantum physics, which explores the fundamental building blocks of everything. So, what are the main theorems in quantum physics? This is the question that we will focus on today.

Firstly, let’s look into what the fundamental building blocks of the world actually are. Let’s take humans as an example. Humans have organ systems, such as the circulatory system. In these organ systems, there are organs such as your heart. So then, what creates your heart? Tissues. Not the kind that you use to blow your nose, but something that allows your heart to be formed. Then, what makes up a tissue? A tissue contains cells, which are the most “basic” structure in your body. A cell has many organelles, but let’s look into the nucleus in particular, where genetic information is stored in the DNA using amino acids. In amino acids, there are things known as elements. Looking at the periodic table of elements, you can see 118 elements. Let’s take a look at a helium atom. A helium atom contains two protons, two electrons, and two neutrons. It is known that a proton has a +1 charge, a neutron has a 0 charge, and an electron has a -1 charge. 

Now, here is where quantum physics starts. These protons and neutrons are made out of quarks. Protons contain 2 up-quarks and 1 down-quark, whereas neutrons contain 2 down-quarks and 1 up-quark. By algebra, we get that the charge of an up-quark is +2/3, and the charge of a down quark is -1/3! But how can something have a partial charge? Let me explain. We used to think that protons, neutrons, and electrons were the smallest thing and could not be broken down further. Therefore, we defined their charge as 1, 0, and -1, respectively. However, their actual change is not 1. In fact, the charge of a proton is around 1.60217663*10^-19 coulombs. When quarks were discovered, however, they decided it was unusual to change a pre-made definition, so they went with fractional charge instead. 

Now that we know what the “smallest” indivisible thing is (electrons and quarks), let’s consider the motion in such a state. The biggest problem that we have with observing motions with such small particles is that you can’t observe them at all! There are two reasons for this. Firstly, these particles are too small to be observed by the naked eye. Thankfully, the development of modern technology now allows them to be seen. However, the biggest problem is that these particles have such a small mass that light itself is able to “hit” one of these particles and can change the motion of it! Why can’t we see these particles, you ask? For us to see something, light has to be reflected from the object, and the reflected light has to come towards us. But when these objects get hit with light, their state of motion changes. This is known as the observer’s effect. 

This actually shocked Einstein. One of his famous quotes is “God does not play dice with the Universe.” While this may make it sound like Einstein is completely against quantum physics, that is not true. The truth is that Einstein supported such developments, given that he contributed to the creation of the subject through his research. What he did try to do was prove that the theorem was incomplete, and perhaps was missing some kind of variables. The weirdness of quantum physics comes from the fact that it states that a particle could be in two states at once. Schrödinger, one of the key researchers, has provided an analogy. Let’s imagine there is a cat in a box. This box has a 50% chance of killing the cat in an hour. Then, just before you observe what is inside the box after an hour, the cat could be dead or alive at the same time. This probability is what seems to bother Einstein, because why would these things be random? All the previous theorems and laws defined things with certainty, but going into such a small area to investigate breaks such certainty. After all, you can’t even observe it with certainty.

I hope you enjoyed this article, and if you have any questions, don’t hesitate to ask me through my email (walter30661@g.lfis.edu.hk).

Parabola and its Uses

Parabolas! This is the shape of the quadratic functions that you learn in secondary school. Most of you would find this uninteresting, and think that you have to memorize everything. And that is partially true. However, in this article, I will be trying to talk less about the math involved with parabolas, and taking more time to look at how and why parabolas are used in real-life. 

Now, here is the fun part! When rays of light (anything without mass works, but we’ll take light as an example) are parallel to the axis of symmetry, the parabola can reflect light and focus it on, you guessed it, the focus. This is due to the curvature of the parabola allowing the reflected light to pass through the focus. This could be proved mathematically, but I won’t bother everyone with the mathematics, as the most important thing right now is not the way we get to the results, but the result itself.

This magical property of parabola is used a lot. I can guarantee you that at least 10% of the world’s population use it, and probably even more in the future. The reason is due to cars! What does a car have anything to do with light and parabolas? The flashlights in cars, and flashlights in general, always use a light source with a parabolic reflector (where the light source is placed at the focus of the reflector), allowing parallel beams of light. However, this is just a single application of parabolas. This technology is used in satellite dishes, solar power systems involving focusing sunlight (to perhaps cook food), telescopes (to see distant objects more clearly), and even more!

I hope this article made sense and didn’t confuse you too much, and if you have any questions, don’t hesitate to contact me at walter30661@g.lfis.edu.hk.

Sources:

Image source: 

http://mathsisfun.com/definitions/directrix.html

https://www.motorbiscuit.com/number-car-owners-world-less-think/

Optics in Medicine

Optics are used in the medical industry by doctors and scientists to see inside the body, diagnose diseases, and even treat them. Optics in medicine is not a new concept, but it has grown significantly with advances in technology. 

One of the most common applications of optics in medicine is medical imaging. For example, endoscopes are thin, flexible tubes with tiny cameras and fibre-optic cables that guide light deep inside the body, allowing doctors to see the inner structures of the stomach, lungs or even blood vessels without making large incisions. Another imaging method that uses light is Optical Coherence Tomography (OCT). This technology uses near-infrared light waves to create detailed cross-sectional images of the retina. OCT is a widely used technique in ophthalmology to detect diseases such as glaucoma. Since it is non-invasive and painless, it effectively helps to preserve vision and prevent blindness. Similar to OCT, X-rays and CT scans are invisible to our eyes. However, the light of X-rays passes through soft tissues and is blocked by bones, which creates images that reveal fractures or hidden problems. 

Besides imaging, optics is also used in laser surgery. The word “laser” stands for Light Amplification by Stimulated Emission of Radiation, and it refers to a highly focused light. In the medicine industry, lasers are used in several ways, including LASIK, a corrective eye surgery where the shape of the cornea is adjusted to improve vision. Lasers are also used to remove tumours, seal blood vessels and remove scars. Since lasers are often more precise and less invasive than traditional surgeries, they reduce recovery time and lower the risk of infection. Moreover, in phototherapy or light therapy, blue light is used to treat newborns with jaundice, a condition where a baby’s skin and eyes turn yellow due to high bilirubin levels. By exposing these parts of the baby’s body to a specific type of blue light, doctors can help the body break down bilirubin and reduce its symptoms safely. 

In addition, specific types of light are used in cancer treatment. Photodynamic therapy (PDT) involves using a light-sensitive drug that becomes active when exposed to a specific wavelength of light. When it’s activated, the drug destroys nearby cancer cells. This technique is still being researched and improved, but it’s currently targeting to cure tumours with minimal damage to healthy tissues.

As technology advances, the potential for optics in medicine continues to grow. Light is fast, precise and non-invasive; doctors are trying to utilise these properties to diagnose conditions earlier and treat them more effectively.