In its simplest of forms physics is the natural science that involves the study of matter and its motion through space and time, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.
Every so often someone naively states that we know everything there is to know about physics but this may never be the case. With every day that goes by we learn something new about physics and every so often there is an extraordinary ‘WOW’ moment, let us use Albert Einstein’s landmark articles establishing the theory of special relativity as a perfect example.
Not only does the study of physics provide us with countless ‘WOW’ moments the science also never ceases to amaze us with some bizarre, strange and weird phenomenon that make your jaw hit the floor at its complexity and simplicity in the same breath.
1 – The Muesli Effect
The muesli effect is a phenomenon that is perfectly made for demonstrating over your family breakfast table. If you pick up your bowl of muesli and gently shake it up and down common sense would make you expect to see the heavier and larger objects such as nuts sink towards the bottom. This is an obvious effect of gravity and we all know that gravity operates in a very simple manner. Of course in this case the exact opposite happens and the larger and heavier bits in your bowl of muesli start floating to the top.
You could even try this experiment with a bowl of mixed nuts and you will get the exact same result only this experiment would perhaps be named the Brazil Nut Effect.
TO understand what is happening here we must look at something called the granular flow which is a somewhat touchy subject for many physicists. What is happening when you shake the bowl of mixed nuts or muesli up and down is the granules begin to travel up and down the inside you bowl which creates flow cycles from the top to the bottom and then back again. For some reason the larger granules appear to reach the top surface and then get stuck, unable to flow back down to the bottom of the bowl. This leaves a juicy collection of the largest fruit, nuts or muesli on top of your bowl.
What are we to learn from the muesli effect? Well ,for starters we know that playing around with your food may not be polite but it sure is fun and educational
2 – The Cheerio’s Effect
Cheerio’s, much like most cereals floating in a bowl of milk, always clump together and cling around the sides. This is something that we see so much of and on such a regular basis we tend not to notice it as anything strange or unusual but if you think about it there is a lot of freaky shit at work here. In fact Cheerio’s clumping together at the side of your bowl has taken the last 20 years for scientists to understand it.
The main thing you must look at here is the buoyancy of the Cheerio’s and the surface tension of the milk in the bowl. Whenever an object is on the surface of a fluid the floating object causes it to deform up if it is buoyant or deform down it down if they are not. We would expect a non-buoyant object to sink from the surface but it is actually supported in place by the surface tension of the fluid. Another thing that happens with the surface of the fluid is that it deforms upwards around the edges of the bowl. There are different objects that will then appear to attract or repel each other or the side of the bowl as they try to reach either the highest or lowest point they can.
Fascinating stuff, eh? Who would have thought physic worked so hard in a bowl of Cheerio’s.
3 – Prince Rupert’s Drop
Prince Rupert’s drop is a relatively simple object that has some pretty amazing properties. If you are to drop molten glass into cold water it will quickly solidify into a tadpole shaped lump complete with a fat head and a long tail. Surprisingly the head can withstand heavy blows from a hammer and will not break due to the extreme stresses that were created the very rapid cooling process. It actually is behaving very much like toughened glass.
If you then went and broke off the tail of the tadpole shaped glass the internal stresses are suddenly released and the thing will just explode leaving nothing but a very fine powder.
4 – Dark Matter and Dark Energy
We now know that galaxies in the shape of a disc spin so fast in space that they should actually fly apart in the same manner your fruit smoothie does when you forget to fix the lid on the blender. Even if we take into account the extreme gravitational forces produced by all of the stars, planets and fine dust there would still not be enough energy there to hold a disc galaxy together.
You may well shrug your shoulders at this but it actually presents us with a huge problem. Simply put either our best theories about gravity are totally wrong or there is something out there such as “dark” matter. If this dark matter really does exist then it may well explain how galaxies don’t spin apart but unfortunately we are unable to see, hear, smell or even detect dark matter. To put this problem into perspective try considering that scientists believe dark matter probably makes up around 90% of our universe. Take a look around the room you are in and imagine that 90% of that room is totally undetectable. You know it is there you just can’t detect it. Mind blowing isn’t it.
If you think dark matter is mind blowing then you will find dark energy even stranger. We are pretty sure that the universe is constantly and mysteriously expanding. To date the best idea that we have is that there is some form of undetectable energy field filling up any empty space and pushing everything apart. Once again dark energy is totally undetectable yet it makes up around 70% of our known universe.
The really, really scary thing here is that based on these numbers the universe and the very planet we live on is 160% theoretical. You might not even exist given those type of odds.
5 – Time Dilation
According to everything that we know and understand about the laws of physics it is impossible for anything to travel faster than light. Even if we had some remarkable method to reach the speed of light we would find that regardless of how fast we travelled light would always travel at the same speed relative to us.
This is probably more confusing than bizarre except for one consequence of special relativity: moving clocks run slow.
Imagine if you will that you are running late for an appointment so you grab the keys to your super powerful and super-fast car and decide that you will travel close to the speed of light so that you can be on time. When you pull up at your appointment your watch says 10:59am and you think to yourself you have made your appointment with a minute to spare. Unfortunately you have actually failed to make your appointment on time and the reason behind this is that you were moving so fast that your watch was running slow compared all of the stationary clocks outside your car. To you the time may well be 10:59am but to everyone else who was not in your car the time could be anything from one minute in the future to many years in the future depending on the length of your journey.
This phenomenon is what is known as time dilation and its effects are very real, although they are nearly undetectable when travelling at the speed of sound. The clocks on board Global Positioning Satellites are deliberately made to run slow so that they remain in step with the clocks on earth while they’re in orbit. Failure to do this would result in a positioning error of 10km accumulating each day.
6 – Time, the Strangest of the Them All
Anyone who thinks the idea of time dilation is weird is about to find that there is something even stranger and that is time itself. Time is actually one of the strangest things in the entire universe and even though we know that time has a direction of forwards we can’t see beyond that. Yes, we travel forward through time but we are unable to explain what or see what time is beyond present time and therefore we cannot explain why everything does not just happen all at once.
The only thing that we think we might know is that time has a forward direction because of the Second Law of Thermodynamics. This law states that the amount of disorder in a closed system increases with time.
Imagine smashing a glass. There is no physical reason why that couldn’t have happened backwards, with all the pieces flying in the opposite direction and spontaneously forming a complete glass. But that’s a highly ordered, low entropy condition. Common sense and the second law tell us that the chances of that happening are so small compared to the alternative that it just won’t happen.
Put another way, time moves forwards because it’s more statistically likely than moving backwards, which basically proves the point that we don’t understand time at all. It’s also why Doctor Who is the only person who can build a perpetual motion machine.