Posted in Science & Nature

Zero Gravity

With the development of technology, we are now at a point in history where there is an abundance of video footages taken in space. Thanks to this, the general population can visualise the strange phenomenon that is the lack of gravity in space. We are able to see videos of objects and astronauts gently floating and even strange phenomena such as tears simply pooling around a person’s eyes rather than streaming down the face. Most of these scenes are from places such as the International Space Station which is in orbit around the Earth, as there has been no expeditions leaving Earth’s orbit since the last moon landing in 1972.


However, the common misconception is that objects in space stations are in zero gravity conditions. Objects in orbit are still under the influence of Earth’s gravity, which is why they do not fling out into the depths of space. So why do astronauts in space stations look like they are not under the influence of gravity? The reason is that an object in orbit is travelling incredibly fast.

The International Space Station is about 420km above the surface of the Earth. Here, it experiences about 90% of Earth’s surface gravity, meaning that theoretically, it should fall straight back. However, the ISS is travelling at 8km/s (27600km/h) sideways at the same time – the orbital speed. Because of this, the ISS is falling back to Earth at the same rate as it is travelling tangentially away from Earth. This makes it travel at a blistering speed in a circle around the Earth.

Not only is the ISS free-falling around the Earth, but so is its contents. Therefore, the astronauts inside look like they are in zero gravity, but are in fact simply in free-fall, much like a skydiver. In this state, they experience no “weight” as the g-force becomes zero and the astronauts accelerate at the same rate as the ISS. Ergo, the astronauts are “weightless”, not in “zero gravity”. This condition can be simulated on Earth in the so-called “Vomit Comet” – an airplane designed to fly up and down along a certain path, to produce a weightless, free-fall when it falls.


Posted in Science & Nature

Newton’s Apple

Common belief is that Newton discovered gravity after an apple dropped on his head. Although there is no historical evidence to support this myth, it has become a popular story. There are two common responses to this story: the first is “Wow, Newton was a smart cookie” and the second is “Pfft, I could have discovered gravity without an apple, it is such an easy thing.”

The latter group of people are idiots. Newton did not “discover” gravity. Human beings have known that objects fall to the ground since the dawn of time and have utilised it in ways ranging from sports to killing other people by crushing them with giant rocks. Even animals know of the concept as seen by eagles dropping turtles on rocks to crack the shell. In fact, if you could not figure that out, then you would really be an idiot.

The reason why Newton is famous is not because he found that apples fall from trees, it is because he observed the phenomenon, noting that it was always perpendicular to the ground, which in combination with the knowledge that the Earth is round suggests that objects tend to fall towards the centre of the Earth. Again, Newton’s brilliance was not that he simply observed an apple falling, it was that he pondered it and spent years researching it until he discovered the way gravity behaves. He devised formulas to estimate how gravity functions, even applying it to predict how the moon orbits around the Earth. Thanks to Newton, we are able to model the world around us and send rockets to the moon without launching our astronauts in to the depth of space with no hope of recovery. 

Interestingly, physicists still do not know what causes gravity. There are many theories, such as particles called gravitrons attracting two objects to each other. Although the mathematics of two objects attracting each other has been accurately calculated, it is unknown what causes it. Only after you discover the truth behind how gravity functions can you say that “I could have discovered gravity in my sleep” (actually, even then you probably spent decades just trying to grasp the concept).

Before you criticise, know what you are criticising.