Monthly Archives: July 2003

Bubble Wonders


      In today’s VERITAS we will look at some of the properties of bubbles. We will look at some phenomenon that are caused by bubbles and their collapse.

Almost all the information presented in this VERITAS has been gathered from the article “Bubble Puzzles” ( Physics Today Feb 2003 issue). If any of you wants to read the complete article, you can take the magazine from me.

      Bubbles occur everywhere. But there are several phenomenon regarding bubbles that have still not been explained. For example: bubbles with a radius larger than .8mm do not rise up straight in water. They zig zag when they rise through water. Leonardo da Vinci was the first to notice this. The Physics of this is so complicated that we still do not have the exact equation for this.

      Bubbles can be injected in fluids. Bubbles can also form spontaneously in fluids. Such fluid bubbles contain the fluid’s vapour. This process is called cavitation( or nucleation).

Cavitation occurs in a liquid when the local pressure drops below the vapor pressure of the liquid. One way to achieve this is to heat the liquid to a level when its vapor pressure becomes higher than the local pressure. For water it happens at about 100 degrees Celsius. At this point bubbles are formed everywhere in the water. These bubbles contain water vapour and not normal air. So in water cavitation is more commonly known as boiling.  Also see the VERITAS on Super Heating ( VERITAS: Superheated Water 20 Mar 2003

      Another way to produce cavitation is by increasing the flow of a small part of the liquid with respect to the other parts. In world war 1 the Royal Navy approached Lord Rayleigh with a problem: the propellers of fast moving boats and submarines used to get damaged without an apparent reason. Lord Rayleigh analysed this and found the reason:

the propellers of these boats used to cause cavitation in water because of their high speeds. This cavitation produced bubbles of large sizes next to the propeller blades. When these bubbles collapsed they damaged the propeller blades!!!

Even today cavitation is a limiting factor for ship and submarine speeds.

      There is an animal which uses this property of bubbles to kill its prey. The snapping Shrimp has two claws: one normal size and the other giant size. To catch its prey it closes its giant size claw so rapidly that a jet of water orignates from it.

This high speed water causes cavitation bubbles and when these bubbles collapse they emit sound in form of shock waves which kill the prey. The shrimp then uses its normal size claw to grap and eat its prey. These snapping shrimps live in huge colonies( in San Diego bay and around Florida). They cause so much noise that it disturbs submarine communication.

      Another interesting phenomenon associated with collapsing bubbles is Sonoluminescence: the generation of light flashes when sound waves cause bubbles to collapse. We will not discuss this here because it has been covered in detail in a earlier VERITAS(  VERITAS : Sonoluminescence Sept 1999  Sonoluminescence is still an unexplained phenomenon. The amount of light emitted from such bubbles is huge( 10,000 degrees Celsius types).





  Go, wondrous creature! mount where Science guides:                 

  Go, measure earth, weigh air, and state the tides:                 

  Instruct the planets in what orbs to run,                          

  Correct old time and regulate the Sun;                             





      In March 1610 Galileo pointed his homemade telescope towards Jupiter. He saw 4 stars near Jupiter. A few days later he noticed that Jupiter had moved from its previous location and the 4 stars followed Jupiter. Another astronomer Simon Marius also saw these “stars” and people realized that they were watching the moons of Jupiter.

According to mythology the Greek God Jupiter had several love affairs. Some of them were with Io,daughter of the River,Callisto of Lycaon, Europa of Agenor. Jupiter also had a son Ganymed,  who had the shape of an eagle. The four moons were thus named Io, Callisto, Europa and Ganymede. These moons were called Galilean Moons. VERITAS readers, today we will study Europa.

      Europa is a mysterious moon. The more we learn about it the more mysteries it opens for us. It is the sixth largest moon in our solar system( Ganymede is the largest). It has a diameter of 3138 Kms.It is much lighter than earth. It orbits Jupiter at a distance of 671000 Kms.

      The strange thing about Europa is that it is a VERY smooth moon. From a distance it appears to be as smooth as a billiard ball.

When you get close to it you can see a complex network of lines on its surface. Pictures from the spacecraft Voyager show pale-yellow icy plains with red and brown regions. Long cracks run for thousands of Kilometres.

None of the structures on this moon is more than a few kilometres high which makes it the smoothest body in our solar system. To understand the significance of this lets compare the surfaces of Earth and MOon.

The Moon and the Earth have been hit equally by large meteors. The surface of MOon is filled with craters all over its surface making it a very rough surface. You hardly see any craters on the Earth making it a smooth body. The reason for the disappearance of the craters on the Earth is because there is a huge amount of geological activity going on here( storms , floods, rains, wind, earthquakes etc). These geological activities fill up the impact craters thus making the body smooth. Ganymede and Callisto are very rough and are heavily cratered.

Europa could not have escaped the bombardment of meteors that hit the other moons of Jupiter. The only explanation of its smoothness? There is a huge amount of geological activity going on there!!!!!!!!!!!!!!!!!!!!!!!!!!!

      Europa has a surface looks like broken glass which has been repaired by icy glue. What kind of activity goes on in its surface? The surface is covered with ice. In a battle of Huge dimentions each day the ice is pulled in 2 opposite directions: By Jupiter from one side and by the other moons from the other side. The ice stretches and compresses till it cracks after several days. Almost immediately stuff from below the ice comes up and repairs the cracks. It comes up and immedialety freezes to repair the crack! What is this stuff? THis is water! The ice on the surface of Europa covers oceans of water!!!!!!!!!!!!!!!!!!!!!!!!!

These oceans might be as deep as 50 kilometres.

      Can life exist in these oceans? We know that liquid water is one of the major ingredients of life. But what about energy( sunlight). We have seen that in Earth’s oceans life can exist even as deep as the Marinas Trench supported by Geothermal Vents(See VERITAS: The Limits of Ocean Depth, 4 Jun 2003). So why not?! It is definitely a possibility. The three bodies( apart from Earth) which might have the possibility of life are Mars, Europa and Saturn’s Moon Titan(a possible subject for VERITAS a few months/years from now??)

      How do we know so much about Europa? Most of this information has come to us from the Galileo space probe. Galileo was launched in 1989 and reached close to Jupiter in 1995. It discovered several new satellites of Jupiter bringing the count to 61! The mission wil end when Galileo falls into Jupiter in Sept 2003.

      See the attached pictures of Europa and Jupiter with the four Galilean Moons of Jupiter( A family picture). Can you identify Europa in the “family picture”?






  Go, wondrous creature! mount where Science guides:                 

  Go, measure earth, weigh air, and state the tides:                 

  Instruct the planets in what orbs to run,                          

  Correct old time and regulate the Sun;                             




Ludwig Van Beethoven


      In today’s VERITAS we shall meet one of the greatest musicians of all time. His story is the story of a constant struggle to create the deepest music known to man. He searched for beauty in his life. He could not find beauty in the real world.

He found it in music.

      Beethoven was born in Bonn on 17 Dec 1770. His father was a singer. His father pushed Ludwig into music from the very early age of 5 years. Sometimes the father used to come drunk at night, would wake Ludwig and ask him to play. Ludwig was sometimes forced to play in front of his father’s drunken friends. Inspite of his father’s brutal teaching methods Ludwig developed a love for music. He went to study music in Vienna in 1787. There he met the great Mozart. But his stay in Vienna did not last long. The same year his mother died and he had to return home to earn for his two younger brothers and a sister. Ludwig’s father spent all his money in getting drunk and Ludwig had to support the family.

      He went back to Vienna in 1792. He tried to study music under several famous musicians but did not like any of them much. He decided to find his music himself. He earned money not by composing but by playing piano in front of audiences. In 1800 he composed his first symphony and in 1801 the moonlight sonata.

      In 1801 Beethoven realized that his hearing was not as good as what it used to be. He was going deaf! That caused a great turmoil in his life. A musician who could not hear!!! He started avoiding friends and retreated to himself. He did not want other people to find out his condition. He started mistrusting people around him and got involved in several arguments which he later felt guilty about. His career as a pianist was over.

      A doctor friend sent him to Heiligenstadt, a village outside vienna with the hope that the calm countryside would improve his hearing. Beethoven was hopeful again. The calm countryside cheered him and he produced the joyous Symphony no 2. But soon he realized that his hearing was getting worse and that it had no cure. Beethoven decided to commit suicide. He wrote a long suicide note to his brothers. His note is now known as the Heiligenstadt Testament. In this document he explains his point of view about life, he explains his tragedy of deafness, he also says that only his music could inspire him to live. Perhaps his music did inspire him to live and he dropped the idea of killing himself.

      After this his music became deeper. In 1803 he wrote the 3rd Symphony(“Eroica”). The years from 1804 to 1808 were pretty bad for his personal life. He fell in love with several women one after another but his dream of love remained fulfilled. He never married. But his music became more intense. He wrote the 5th and 6th symphonies in 1808.

      He cut off the legs of his piano so that he could place it on the floor and feel its vibrations. He would sometimes place his ear on the piano to feel its notes. After deafness Beethoven imagined music and his music became more free.

      In 1812 he wrote a long letter to an unidentified lady whom he addressed as the “Immortal Beloved”. This letter was as long and as emotional as the Heiligenstadt Testament and shows how depressed and lonely he was during that time. This letter was discovered in Beethoven’s secret drawer after his death.

      In 1815 his brother Casper Carl died. This was a great tragedy for Ludwig. He almost stopped composing. He was supposed to take care of Carl’s son Karl. But Karl’s mother wanted custody of the boy. This resulted in a long and abusive legal battle which took a serious toll of Beethoven’s health.

      He composed his 9th symphony in 1823. He was completely deaf at this time. He died in 1826. His funeral was attended by more than 20,000 people. 

      Beethoven’s life reminds me of the following lines from a poem by George Eliot:

             O may I join the choir invisible

               Of those immortal dead who live again

               In minds made better by their presence:

               live In pulses stirred to generosity,

               In deeds of daring rectitude, in scorn

               For miserable aims that end with self,

               In thoughts sublime that pierce the night like stars,

               And with their mild persistence urge man’s search

               To vaster issues.





  Go, wondrous creature! mount where Science guides:                 

  Go, measure earth, weigh air, and state the tides:                 

  Instruct the planets in what orbs to run,                          

  Correct old time and regulate the Sun;