Everyone Wants to Know

Tag: philosophy

  • The Beginning of the Unthinkable

    The first blog in a three part series on the modern marvel of the century: quantum mechanics.

    But what exactly is quantum mechanics, and why has it fascinated scientists for over a century? From the strange behaviour of particles such as photons and quarks to the possibility of revolutionary technologies like quantum computers, quantum mechanics lies at the centre of some of the most exciting ideas in modern science. Understanding it means stepping into a world where the rules of everyday life no longer seem to apply. Albert Einstein himself had a love-hate relationship with the idea. It challenges you to forget everything you think you know and embrace the unthinkable.

    Quantum mechanics is probably the second most sought-after field in physics, following astrophysics. It is where ground breaking theories emerge, strange ideas challenge our understanding of reality, and physicists dream of having a discovery or theory named after them.  Recently, quantum computing has pushed quantum mechanics further into the spotlight, with new breakthroughs and mysteries appearing almost every year.

    Quantum mechanics is the description of the behaviour of subatomic particles such as photons and electrons, how they work and how they interact with light. Richard Feynman, a physicist in the mid-1900s said that particles are particles (not waves) and they can hop from place to place with a particular probability. To calculate the probability that the particle will be at a different place later is as follows: assign a probability to every point in the room and then add them up. This is called the path integral formulation and can be used to calculate the probability of a particle travelling from point A to B. If a particle travels from one corner of a room to another, the path integral formula can be used to calculate what the probability of that particle moving to another point in the room is.

    Before the turn of the 20th century, scientists believed light was a transverse wave and particles could never be waves. According to Newtonian physics a hot object should emit infinite energy at short wavelengths. Red light gives out some energy; blue light gives out more energy and tiny wavelengths like ultraviolet gives out huge amounts of energy. Their math stated that a hot object should pour out endless energy in tiny wavelengths. However, there are some clear problems with this theory as it would mean some objects would have infinite energy which means, that energy would come from nowhere. We now know that this would go against the theory of conservation of energy and evidently made no sense. Their mistake became known as the Ultraviolet Catastrophe.

    Max Plank in 1900 had a bold idea. He said that light energy does not come in smooth endless amount but instead it comes in tiny packets, called quanta. For example, you cannot use half a coin, you must use a whole coin. This idea meant that very tiny wavelengths need bigger energy packets (quantum), which meant that shorter wavelengths emitted more energy.

    Einstein expanded on this further. He thought, what if light itself was made up of quanta. The colour of the light tells you how ‘energetic’ it is. The shorter the wavelength, or the more purple the colour, the stronger the packets. So, in theory a blue hot iron would actually emit more energy than a red-hot iron. Einstein used this to explain the photoelectric effect. This is when shining dim blue light on metals could knock electrons out, but very bright red light sometimes could not. This led Einstein to believe that the energy was not about the total brightness, rather about how strong each tiny packet is. The blue light had a small number of large packets, and the red light had a large number of small packets. He called these energy packets, photons.

    Photons are a massless particle which means they do not feel a gravitational attraction. They move at the speed of light and have no rest mass; this means that a photon is always moving at the speed of light. These photons sometimes acted like waves and sometimes acted like particles. This meant that tiny particles could be in many possible states at once and its state only becomes definite once measured.

    This arises from Schrödinger’s theory that a cat can be both dead and alive at the same time. He imagined that a cat is placed in a box with radioactive material that has a 50% chance of killing the cat in the next hour. At the moment just before you open the box, the cat is both alive and dead at the same time. It is only once you open the box that the cat’s single state is visible. This quantum theory perturbed Schrödinger so much that he gave up physics and moved to biology.

    Quantum mechanics began as an attempt to explain strange mysteries about light and atoms which normal Newtonian physics simply could not explain, but it ended up completely changing our understanding of reality itself. From photons and wave-particle duality to uncertainty and superposition, quantum theory reveals answers to problems that had bizarre solutions earlier. Although many of its ideas seemed confusing at first, quantum mechanics has helped scientists build technologies like lasers, computers, and MRI machines, while also opening the door to future innovations such as quantum computing. Most importantly, it reminds us that not all questions are answered and certainly not all questions have arose.

  • Our Perception vs. Reality

    Look around you. You can see millions of colours, different shades, hues and saturations. However, have you ever thought, what exactly is colour? The Oxford dictionary states it as the property possessed by an object of producing different sensations on the eye as a result of the way it reflects or emits light. In simple terms it is how the absorbed, reflected or transmitted white light enters your eyes. Visible light is part of the electromagnetic spectrum, with red having the longest wavelength and violet light having the shortest.

    The visible spectrum covers a vast range of colours and was originally found by Sir Isaac Newton in an experiment he conducted in the mid-1660s. He tried to split white light through a prism into the entire electromagnetic spectrum, but naturally he could only see the visible part. He discovered that there were 6 main colours and an infinite range in between. The 6 main colours were: red, yellow, green, blue, indigo and violet. He added orange as an afterthought, simply because he preferred the number 7. Newton’s experiment is an excellent example of the subjectiveness of colour.

    One thing which Newton got slightly wrong was how many colours in the visible spectrum we can actually see. Even though it is known as the ‘visible’ spectrum, we chose not to see some colours. This is simply because our eyes are too sensitive to view the complexities of the world. My favourite example of this is the sky. Have you ever stopped to think, out of all colours, why is our sky blue?

    Rayleigh scattering occurs when the shorter wavelengths of light are scattered in all directions because of the small Rayleigh particles. The colours with the shortest wavelength is purple followed by blue yet we see a blue sky, most of the time. Why is this? Why do we not see a purple sky? Simply because our eyes are too sensitive and do not react well to violet light. Honey bees and other animals which can see ultraviolet, see a purple sky as their eyes receive violet light well. However, for many animals like deer, sharks and whales, the sky can seem grayish blue as they do not have the same number of colour receptors as us. Some birds, on the other hand, have far better eyesight than most species can see the sky in a vivid and colourful blue that we cannot see or imagine.

    Now, I want to conduct a thought experiment. Close your eyes and think of a colour, any colour; but it must be one you haven’t seen before. Go on, pause your reading and really have a try.

    However much you try, you will never be able to think of a new colour. Our brain simply cannot create something that we never have seen and never will be able to see. This is the reason why we could never fathom how birds saw the sky.

    Our perception of colour is based on the combination of three types of cones in our eyes which respond differently to different wavelengths of light. The brain processes these signals to create our subjective experience of colour. Therefore, while we can try to describe colours we have never seen with words, we cannot create or imagine colours that exist outside of the visible spectrum.

    Some women are born with four cones which means they can see a wider range of colours than any other being. Nevertheless, even with three cones, most women can see a wider arrangement of colours. And then there are those who are severely colourblind, during daytime they may see a limited array of colours, but it is proven that they have far superior night vision than any other human.

    This highlights just how subjective colour truly is. Even within our own species, we perceive colour in very different ways. When we begin to consider how other species experience the world, we must ask what does the world actually look like? If each individual sees colour slightly differently, can we really claim that colours exist in any absolute sense? These questions may never be fully answered. After all, how can we definitively explain something that is entirely dependent on perception? Like a paradox, it is something that invites endless thought but no action.

  • Quest to a Perpetual Hourglass

    Secret to the universe’s greatest mystery

    It is the most common noun in the English language and used in a range of proverbs. It flies when we have fun and along with the tide it waits for no one. You try to race against it and often wish you had more of it. Time is one of our universe’s greatest mysteries and physicists spend their lives trying to understand even a fraction of it.

    Wouldn’t it be cool to go into the future, have a peek into your successes and failures, come back and fix it all? In theory, it is surprisingly simple; all you must do is travel at the speed of light. So, why hasn’t anyone taken a trip through time? Actually, everyone has. You, your neighbour, your local newsagent, astronauts and Usain Bolt. The only difference is how far ahead in time. This is all because of time dilation, the difference in elapsed time. Elapsed time simply means the amount of time that passes from the start to the end of an event. For example, if you had two identical clocks, one stationary and another one moving close to the speed of light, the moving clock seems like it is measuring a shorter time or moving more slowly relative to the stationary clock. This applies to other bodies as well. Humans have an internal clock and the faster they move, the slower their internal clock runs, allowing them to travel forwards in time.

    For instance, if you race against Usain Bolt in a 100m race, he will reach the finish line a couple of seconds before you do, well, assuming you are really fast! This means he has reached the future quicker than you have as he has travelled a fraction of the speed of light faster than you. The closer you go to the speed of light, the more apparent are the effects of time dilation. Astronauts aboard the ISS, which travels at 0.000002% the speed of light, experience time dilation on a measurable scale. Astronauts coming back from a 6-month mission are actually 0.007 seconds ahead of us. As the average human reflex speed is 0.21 seconds, this doesn’t make a massive difference. However, some cosmonauts like Oleg Kononenko, a Russian astronaut who has spent a whopping 1111 days in space might be a couple of seconds, ahead in time.

    If you (a person who hasn’t experienced time dilation on a measurable scale) and Kononenko were standing next to each other at a shooting range, Kononenko would see each shooter hit their target 2-3 seconds before you do. Depending on the distance between the shooter and the target, he may see the target being hit before the shooter has pulled the trigger!

    If a person is able to travel a couple of seconds into the future, then how hard could a couple of years be? Unfortunately, Einstein has made that quite difficult due to his special theory of relativity which states that the speed of light in a vacuum is the same for all observers. This is also where his very famous equation E = mc2  comes from. This can be rearranged to say

    m/s. Therefore, for a small mass, you will need infinitely more energy than is describable to travel at the speed of light. For many humans as well as their spacecrafts, the amount of energy required may be greater than the amount we have in this universe itself!

    Travelling at the speed of light is ruled out but what if I told you that there was another way to travel into the future. A way which allows our feet to be younger than our head. As your feet are deeper in the Earth’s gravitational field then your head, it reaches the future first. Similarly, if you spend an average lifespan of 72 years living in La Rinconda, the highest permanent human settlement, situated in the Andes at an elevation of 5,000 meters, then you would be 0.0025 seconds further ahead in time than someone who had been living their whole life at sea level. The person living at sea level is deeper in Earth’s gravitational field and therefore less time passes for them.

    Everything has a gravitational field strength, however, the heavier the body the stronger its gravitational field strength (g). As the earth’s gravitational attraction is not strong enough to experience time dilation on a measurable scale, one must turn to the heavier celestial bodies. Luckily, there are some bodies that are a trillion times heavier than the Earth. We call these black holes. They are dense and heavy with a gravitational strength so strong that not even light can escape once it has crossed the event horizon, a point of no return.

    A black hole’s gravitational attraction is so strong that if you sit just 10km away from the black hole’s event horizon for 7 years then 7,000 years would pass on Earth. This seems like a possible solution for travelling into the future but there is a catch, like with most laws of physics. Our nearest black hole is Gaia BH1 which lies in the direction of the constellation Ophiuchus. To get near the black hole’s event horizon and back to Earth, one must travel for 3,000 years and that too at the speed of light. As the average lifespan of humans is currently 72 years that is not possible.

    So, if you’re hoping to pick up next week’s test paper or perform the latest trends with aliens from outer space, I’m afraid you have to wait, but it might be for the best. The future is unpredictable, and we do not know whether humans would even be alive in 1,000 years, therefore it is best to stick to dreaming about meeting moon colonies or watching the latest sci-fi movies.