Here are answers to some of the questions I get frequently asked on twitter.
How do clouds float in the sky?
Clouds are formed from tiny water droplets that spread out for miles. The droplets are so small that gravity doesn’t really affect them and their fall velocity is negligible. As a result, clouds appear to float on air.
Why does a flame have blue, yellow and orange parts?
It depends on the chemicals present and the temperature of the flame. Cooler flames will appear yellow/orange whilst flames with temperatures above 1800K. In terms of chemicals, a yellow flame is due to a presence of sodium, whilst a blue flame is likely due to a presence of carbon.
How was the moon made?
We currently think that the moon is a result of something colliding with the Earth and knocking debris in to orbit. It is likely that at one point the Earth had roughly 20 ‘Moons’ that coalesced in to the Moon it is today. We think this due to the Moon being formed mainly of the same materials as the top layer of crust of the Earth.
What was there before the Big Bang that started the Universe?
We are not quite sure. Physics sort of breaks down before the Big Bang. However, Stephen Hawking once said in an interview that the theory relies on something called the “no-boundary proposal”.
How is gravity made?
Some scientists think it is made up of particles called gravitons. It is due to the warp of spacetime around an object with mass. Imagine a bedsheet being pulled from all directions so it is tight. If we place a bowling ball in its centre the bedsheet will dip around it. This is what happens to the fabric of spacetime.
How are rainbows made?
Sunlight (visible light) is formed from all the colours of the rainbow mixed together to form a white light. When the sunlight passes through a raindrop, the light is reflected off the back of the droplet at different angles, splitting the white light in to its component colours.
What are atoms made of?
The word atom comes from Greek word meaning uncuttable. However, we now know the atom is “cuttable”. It is made from electrons that exist around a nucleus of protons and neutrons that are in turn made up of elementary particles called up and down quarks.
Do aliens exist?
This is a question I think about often. It is probably best explained by something called the Fermi paradox. This is the contradiction between the lack of evidence of alien life but the high probability of life existing elsewhere. Some explanations to the question Fermi posed (“where are all the aliens?”) is that life is rare or unique to Earth; it is in the nature of intelligent life to destroy itself (global warming, nuclear war); it is the nature of intelligent life to destroy others when they pose a threat (maybe once we pose a threat to alien life they will destroy us with their laser); no other intelligent life has arisen yet; intelligent life hasn’t developed the technology to communicate; they are too far away and lastly; new life might commonly be destroyed by natural events.
Is dark matter real or just a mistake?
There are lots of reasons to suggest the existence of dark matter. Changing our understanding of gravity isn’t enough to explain all of dark matter’s effects. I am however, writing a paper on a theory of dark matter that suggests why it is so illusive, why it has such a strong influence on gravity and where it came/comes from.