I still remember the time I read my first ever research paper and was completely blown away!
The hardest part was that I didn’t know how to get through the paper with all its complexities (how do I even start? , Wait, I didn’t understand this section(Panic!), what do I do with all these references ? etc) and I spent probably like a month trying to understand it but in vain.
Since this is a skill that rarely gets taught, to all those budding researchers I strongly recommend reading the linked article. Trust me it would save you tons of time !
Humans have been pwning gravity from time immemorial- desperately trying to break free from its clutches. And time and again we have found ways to accomplish this. And to use Acoustics to float things around is just elegant.
A standing looks like the one below. It gives us an illusion of Stillness .i.e unlike any rational wave that we know it does not seem to traveling anywhere.
The Sorcerous magician’s priced spot- The node
As you can see, there are places in the waves where there is very less activity ( the red dots ), these are known as the nodes. The region of maximum activity are known as anti-nodes.
You place a water droplet right in the node, where there is very less pressure, the droplet is going to levitate! Why? Well, the particle is locked in place because of the presence of a high-pressure region above and below it. This seals the object in place. That’s the basic working principle.
The Illusion of Stillness
But this is all an illusion! These are formed indeed by moving waves. How you ask?
Tweak the reflection and interference just right ( by adjusting the length of the reflector) and Bam! You have a standing wave!
Invert the wave apparatus 90 degrees and now you have an Acoustic Levitator. I love the Soniclevitation’s neat illustration of how it all works.
Acoustic Levitation – An analogy.
HowStuffWorks elucidates this phenomenon with an elegant river analogy:
Imagine a river with rocks and rapids. The water is calm in some parts of the river, and it is turbulent in others.
Floating debris and foam collect in calm portions of the river. In order for a floating object to stay still in a fast-moving part of the river, it would need to be anchored or propelled against the flow of the water.
This is essentially what an acoustic levitator does, using sound moving through a gas in place of water.
How big an object can you levitate?
I know what you guys might be thinking – How about an Acoustically levitated Hoverboard? Well, a lot of research has been in progress and we have gotten pretty far from levitating merely droplets of water and styrofoam balls.
In fact, we have gone 3D with added maneuverability.
A Boy and His Atom is a 2012 stop-motion animated short film released on YouTube by IBM Research. The movie tells the story of a boy and a wayward atom who meet and become friends. It depicts a boy playing with an atom that takes various forms.
And these sphere shaped beads that you see are indeed Atoms! How cool is that?
Yup, you heard it right! And No! this is not a star trek reference
Oxford scientists in 2009 bombarded aluminium with the most powerful soft X-ray laser. They focused all this power down into a spot with a diameter less than a twentieth of the width of a human hair. At such high intensities, aluminium turned transparent.
The invisible effect lasted for only an extremely brief period of time- an estimated 40 femto-seconds. But hey! The existence of such an exotic state of matter per se, opens up new frontiers for pristine research and technology. As Albert Einstein rightly said:
The process of a scientific discovery is, in effect, a continual flight from wonder.
Everyone knows that a line of standing dominos creates a fun chain reaction when you knock the first one over; but did you know you can use increasingly larger dominos and get the same result?
Professor Stephen Morris knocks over a 1-meter tall domino that weighs over 100 pounds by starting with a 5mm high by 1mm thick domino.He uses a size ratio of 1.5, meaning each domino is one and a half times larger than the last one. This is the generally accepted maximum ratio that dominos can have to successfully knock each other over.
Hans Van Leeuwen of Leiden University in the Netherlands, published a paper online showing that, theoretically, you could have a size ratio of up to two. But that’s in an ideal (and probably unrealistic) situation.
There are 13 dominoes in this sequence. If Professor Morris used 29 dominoes in total, with the next one always being 1.5x larger, the last domino would be the height of the Empire State Building.