Everyone Wants to Know

Tag: physics

  • 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.

  • A Timeline of Innovation

    A trip through the wonders of technology

    My dad is a strange man. Normally, he is not superstitious and never crosses his fingers when he sees a black cat, or salutes to magpies, and tries to open umbrellas indoors! However, when we visited Santa Croce in Florence, at Galileo’s tomb, he suddenly broke character and asked Galileo to bless me with some of his intelligence.

    Galileo Galilei was an Italian physicist who is credited with the invention of some of the most remarkable scientific tools in history, pioneering the laws of motion and the concept of inertia which Isaac Newton later built on. He is also known for his laws on falling bodies which states that bodies, no matter their mass when dropped from the same height will fall at the same velocity in a vacuum. A physicist and astronomer, he is credited to have invented the most powerful telescope of his time. Fast forward today, telescopes are massive lenses in open fields and sometimes even in space, which can see objects thousands of light years away, but Galileo’s telescope was the first of its kind. With his small, yet vastly more powerful than earlier telescopes he could see the moon’s craters and the phases of Venus. This supported the heliocentric model of the solar system proposed by Nicholas Copernicus, where the Sun is at the centre of our solar system and planets revolve around it. This idea was not popular with the Pope and most Christians at the time, as the Bible states that the Earth is fixed and lies at the centre of all things. Which is why in 1610, when Galileo made his ideas public, the Pope’s men interviewed him and when Galileo would not back down from his truth, they put him under house arrest for the remaining 9 years of his life. It is only in 1979 when Pope John Paul II officially declared that Galileo was right.

    His invention of the modern telescope led to a lonely final decade of his life but was it worth it in the end?

    One of the largest ground telescopes is located in the Atacama Desert, Chile and is used for exploring hidden corners of galaxies. It has already captured images of new born stars. This telescope not only helps us detect the life span of neighbouring stars but also at what rate the universe is growing. Due to their large lens size, these telescopes can see objects millions of light years away. For example, the brightest star that we on Earth can see, is called Sirius and is located 8.6 light years away. This means that when we look at Sirius, we are looking at what the star looked like over 8.6 years ago because the light from the star takes time to travel to us.

    In January 2022, James-Webb, a space telescope with a 21-foot lens, was released into space. This telescope broke the record for the furthest celestial body detected; a galaxy 13.5 billion light years away. James Webb captured this image while the galaxy was still at a young age and astrophysicists believe that this galaxy was born only 280 million years after the Big Bang. The James Webb did not just take a photo of a galaxy, but it travelled 13.5 billion years back in time; to a time when Earth didn’t exist and hydrogen was still fusing into helium. It was a large step forward for the space industry, as it produces some of the most powerful and detailed images of faraway corners of our universe. Imagine witnessing stars being devoured by supermassive black holes and the collapse of giant stars into dense neutron stars. These findings have shaped our understanding of familiar concepts like gravitational attraction but also new ideas like spaghettification (what happens to an object when it enters a black hole).

    However, the most remarkable achievement of this particular telescope is the discovery of potential life. The James Webb telescope analysed the chemical composure of K2-18b, a planet 700 trillion miles away. Then scientists back on Earth inspected to find a large number of molecules in its atmosphere which on Earth can only be produced by living organisms. Due to the large proportion of these molecules, scientists believe that if this planet is home to organisms, it is teeming with life. K2-18b is two and a half times bigger than Earth but otherwise remarkably similar; it is a water world, thought to be covered entirely by oceans. The evidence collected by this one telescope is growing, making it more and more likely that there is life in those depths.

    So, we thank you Galileo for sacrificing your freedom. Without it, our knowledge of the entirety of the universe would be limited to still trying to prove the heliocentric model. Young curious minds like mine may never have been drawn to star-gazing. I wish you could see what your small, 51-millimetre telescope has inspired and what information has been found because of it.

    Maybe, my dad was right. A man who started the domino effect that led to these new findings deserves to be treated like a God. On behalf of all qualified and aspiring scientists out there, bless us with knowledge, integrity and innovation like yours.

  • 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.