Monthly Archives: April 2000

Still Don’t know much

 

Today’s VERITAS is a relook at a question that I used to wonder about as a kid and the answers I have about them . I dont have many answers …

But I have more questions …

 

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Question I used to ask (Q_old) : What Is light ? If I shine a torch at the moon at night will the light reach the moon ?

 

What I know (I_KNOW) :

 

   Today I know that light is an electromagnetic wave .

   The Electrical and the Magnetic components perpendicular to each other.

   I also know that it goes really fast ( 3X10^8 metres per second ) .

   I know that it sometimes behaves like a particle and sometimes like a

   wave . I know that you can polarize it , and make a coherent beam ( laser )

   I know that it carries energy ( poynting vector ) . I know how u can

   make light . I know the Maxwell equations and I know quantum optics …

 

What I still dont know ( Q_new ) :

 

   What is the meaning of : Electric field . Okay we can define it but

   how does it “look” . Does the electromagnetic field move through

   space or does light create a new field as it moves ? What is the

   meaninh of : Photon ( particle of light ? No No . A Photon is actually

   a mode of the electromagnetic field . So how can it be a particle ?

   How can you localize it ???? ) . They say that a photon has no mass .

   But it has energy . So cant we convert that into mass ? What happens

   when light goes through a material ? Do the electrical and the magnetic

   field change ( I guess they do ! ) . What happens when light hits a

   electron , atom ? I know that the electron may get some energy and

   go to a higher energy state . But how does the transfer of this

   energy take place ? Is the speed of light actually the final limit

   or can we still hope for something higher. How does Gravity affect

   light ( I know it bends it but I dont know the equation ) .

   Can we freeze light 🙂 ?? 

 

 

Microwave Ovens

 

First let me thank Rakesh Malik for pointing to a wonderful Physics website . It is called Physics 2000 . It teaches you Modern Physics in a very interactive kind of way . A MUST SEE :

 

http://www.Colorado.EDU/physics/2000/index.pl

 

      Todays VERITAS was inspired from this website. How does a microwave

owen work ?

 

 

      A microwave oven just heats up water . All foods have moisture in them

and if you heat the water in the food the rest of the food gets hot too .

A microwave oven just shoots electromagnetic waves inside the oven box .

Electromagnetic waves are waves that have an electric and a magnetic

field component . Now a water molecule has a dipole moment . That means that

a water molecule has an imbalance of electric charges . See figure

 

 

          H

      O

          H

 

        -ve  +ve

 

The molecule as a whole is neutral ( has no net charge ) but there is  a

concentration of -ve charges near the Oxygen molecule . ANd a little

concentration of +ve charges near the hydrogen atoms .

Now when the electric field of a electromagnetic wave “touches”  a water

molecule it rotates it . If there are some water molecule nearby they get

hit . So if the food has moisture the electromagnetic waves of our microwave

oven make the water molecules rotate and hit each other . This produces

heat . ( Heat is just kinetic energy ) .

 

 

That is why the container of the food does not get hot . There aint any

water  in it . And That is why the microwave does not get hot . It aint

got no water.

 

 

And if our food is frozen it takes a really long time to heat up . The

water molecules are “tied” up and they cannot rotate . SO no heat is

produced . So first a little bit of water has to melt and then our

microwave oven can start being effective .

What holds a nucleus together

A quote first :

 

      A scientist is an atoms way of understanding other atoms !!  🙂

 

    Have you ever wondered what holds the nucleus together ? The nucleus of an atom contains +ve cherged protons and neutral neutrons . Why dont the +ve charges just repel each other and break the nucleus ?

 

To understand this we will first have to understand something called :

Exchange Force  . Lets imagine 2 particles of one kind P1 and P2 and a different kind of particle D . Now D can be close to P1 or D can be close to P2 . ie either bound to P1 or P2 . See diagram

 

State 1 :   

 

 

        P1 D                                     P2

 

 

State 2 :

 

        P1                                        P2 D

 

 

 Now the position of D is uncertain ! if P1 and P2 are close then the particle D can flip flop between P1 and P2 ie sometimes be closer to

P1 and sometimes be close to P2 . This is a nice thing for D . This gives D more freedom . According to Pauli’s exclusion principle the system has less energy .

 

If P1 and P2 are very far away then D has to remain attached to either P1 pr P2 and going to the other particle is hard ( it is too far away !) D does not like this . This state is a high energy state .

 

So Physics prefers P1 and P2 to bew close to help D get more freedom .

So P1 and P2 attract each other . They attract each other by the

exchange of the particle D .

 

Similarly the Neutron and the proton attract each other by the exchange

of a particle called meson . The proton gives up a meson and becomes a

neutron . The meson is taken by the nearby neutron which becomes a

proton . So the proton and neutron try to come close to exchange more

mesons .

 

This attraction is very strong . In fact it is the strongest

force known in nature !! It is 10 raised to the power 41 times stronger

than gravity !!!!!!! It is called the strong nuclear force .

 

Does this also answer the question why nuclei have almost equal numbers

of protons and neutrons !!!???

 

But the problem is that is a very short distance foorce . It operates over

very short distances . If the proton and the neutron are very very

close then this force is important .

 

This is why heavier nuclei like uranium are so unstable . The reason is

that the nucleus is so large that the repulsion between the far off

protons beats the nucleur attraction between the far off proton – neutron

pair . So all large nuclei are unstable . Infact there cannot be a nucleus

with a Atomic number of 120 !!!! 

Panama Canal

Here is the story of the construction of Panama Canal . It turned out  to be a much bigger challenge than people first imagined .

 The complete article ” the unkindest cut ” is in www.discovery.com .

 I am just gonna talk about some parts that I thought were important/interesting

 

 

 The idea that a canal should be built thru Panama to connect the Atlantic

 and Pacific ocean and save ships from a 12,000 mile journey around South

 America was as old as 1513 .

 

 The first attempt to make this canal was by the Frenchman : Ferdinanad

 de Lesseps . He had built the suez canal earlier . I 1883 work started

 on the panama canal . 20,000 workers started digging . But progress

 was too slow . The terrain was mountaneous and had thick forests.

 ( suez canal was build thru a desert ) . Then because the french

 cut too many trees , this resulted in landslides . And then disaster

 struck . By 1884 yellow fever( caused by a mosquito ) was killing

 200 workers a month . The project was scraped in 1889 . A failure !

 

 

 In 1903 the AMericans started building the canal after suppressing

 a local revolution and creating a new state “Panama ” . In 1905

 Yellow Fever struck again killing workers . But the Americans had

 a plan . They asked a tropical disease expert Dr Walter Reed to

 suggest something . The plan was executed by Colonel William Gorgas .

 He installed wire nets(worth 90000 $ ) , fumigated houses , improved

 sanitation and by December 1905 the disease was finished !!!!!!!

 

 The person incharge of the canal Stevens was a very methodical

 chap . He spent 2 yrs planning the infrastructure etc . He

 suggested a canal with locks( I dont know what this means )

 But Stevens was replaced by Col Goethals. Goethals executed

 Steven’s ideas and the canal was completed in 1914 . Yippie !!

 

 The total cost : 639 million $ .

 

 If u make a mountain out of the earth moved it would occupy 1 city

 block and would be 19 miles high . coool aint it !!  

A case against sun signs

      We all spend a considerable amount of our time looking at our horoscopes and we also tend to judge others on the basis of their sun signs . Oh he is a typical “Gemini” … I get along great with “Saggis” go the typical statements . Now is there any scientific basis in all these sun signs?

      I cannot consider all aspects of Astrology but lets take a look at one .

 

      What is the basis of the “sun sign” astrology ? Our Ancients observed

that the position of Sun ( as observed from the Earth) retraces a fixed

path year after year . They divided the sky into 12 parts and identified

each part with the constellation of that part . So on 5th October the

Sun would be in Libra ( As observed by the ancients ) . So the person

born on that date ( myself ) would be a Libra . Similarly a person born

on 30 August would be a Virgo ( because the sun would be in the Virgo

constellation ) on that date .

 

So thousands of years ago our ancients observed that the sun is in a particular

constellation for about a month and then the observed the people who were born

on this particular date and made the “sun sign” astrology .

 

      Sounds good ? Now I will tell u what is wrong with this !!

 

      The axis of the earth precesses so that the position of the Sun

with respect to the constellations changes after about 700 to 1000 years .

What does this mean ?

 

      When I was born ( 5th Oct 1974 ) the Sun was not in Libra . It

was in Virgo . If I was born on 5th October 1074 then the sun would

have been in Libra . See that ??? There is a shift of one constellation

. For everyone .

 

      So if the AStrology books say that u are Aries then they are wrong

. The sun was actually in Pieces when u were born . So what sun sign

shoud u read ??? beats me .

 

      So the sun was actually in the sun sign x-1 if the astrology

books say that it was in x .

 

      Astrology ( even if there is any truth in it ) is horribly

outdated !!!!!

 

Symmetry in the Human Body

The June 1999 issue of Scientific American contains a very interesting article about the symmetry of organs in the human body . From outside our body looks symmetric ie our eyes , nose , ears have a left right symmetry.

From inside however , there is a preferred direction of each organ . The

heart is on the left side , the right lung has more lobes than the left .

      The insides  of our bodies have been arranged so as to pack the max amount of stuff in the little space . Even if the organs were flipped ( ie all of them ) the person will still be perfectly healthy.

      There is a rare condition known as Situs Inversus . It occurs in 1 in 10,000 odd cases and the person has all his organs flipped . The heart is on the right side , the liver on the left , stomach on the right . The person is still perfectly fine .

 

      However there are some dangerous conditions too : A condition known as isomerism can make a person have 2 right sides or two left sides of his body . That person may have 2 spleens or no spleen . 2 hearts or no heart .

This is a fatal syndrome and the dude soon dies .

       How does the body know which side is which and when does the arrangement

or organs take place ???

 

      It all starts in the embryo . The embryo in its earliest stages

is perfectly symmetric . Then after some time the symmetry is broken .

THis is during the development of the heart . A protein called

“Sonic Hedgehog” is released and the tube of the heart loops opposite to it .

THIS IS THE CRUCIAL STAGE !!! The tube of the heart loops opposite the

place where this protein is released . After 18 hours this protein is

inactivated . But it has done its job . Told the embryo what the symmetry

of the final dude will be . But this alone does not make a “normal ” dude .

More harmones are required . And the place where they pop up is crucial.

The Sonic Hedgehog and the Nodal harmones have to be on the left side and

the Activin Beta-B has to be on the right side for a normally placed

heart . Researchers then did an experiment . They put some extra

Sonoc Hedgehog and the Nodal on the right side . So both sides have

these harmones . TThe embryo got confused and the placement of the heart

got random !!

 

      The complete article is very interesting and has some interesting

pictures too . The copy of Scientific American is in my cube . Interested

people can come and see it .  

 

The works of Escher

Today’s VERITAS is about paintings . So you have to see each link through ur web browser . Otherwise it is no use .

      Today we will talk about the works of a very imaginative painter .

His name was M.C Escher . He was born in 1898 in Holland . His father

was a civil engineer . M.C was not very good at studies and never managed to

pass high school . But he had a great interest in paining and architecture .

      In 1921 he started experimenting with a very different style .

His paintings were not related to relatty as we see it . It is more

fantasy. It is a different way of looking at reality .

 

For example see his drawing hands : Each hand draws the other :

 

 

Escher experimented with trying to represnt infinity in his paintings .

 

His paintings also have “infinite loops” . For example see his waterfall.

The water is always at the same level . But still it falls down at the end :

or see his Ascending,Descending . One set of people is forever climbing

the stairs . The other set is forever coming down :

http://www.worldofescher.com/gallery/AscendingDescendingLg.html

 

This one is really wow . This is “Another World ” . The great thing is

that whichever way u look at it you see a replication of a whole

world . You feel that you are standing on a cross road between

worlds whicg are images of each other .

http://www.worldofescher.com/gallery/AnotherWorldIILg.html

 

Another one that can “hit” you is Day and Night . This is one of his

most popular works . See this and feel it . Half the painting is

day and the other half is night .

 

http://www.worldofescher.com/gallery/DayAndNightLg.html

 

Escher died in 1972 . By this time he had become really famous .

He is really respected by Mathematicians and Atrists . His

works contain the description of matematical concepts of infinity ,

endless loops , self swallowing sets … in the form of paintings .

The power of one

Today’s VERITAS is a tribute to the patience and perseverance of one man whose hard work paved the way for Physics . If he had not done what he did we would have been atleast a 100 years behind( what we are now ) in Physics and Astronomy . And the wow thing is that he himself never did it for that end in mind . He was just doing his daily work .

      Tycho Brahe( 1546-1601) was a Dutch Astronomer. We wont go much into the details of his personal life. Tycho was a very influential man and was very close to the Danish king Fredrich . The king gave him an island .

      Tycho became the owner of an island called Hven ( near Copenhagen ).

He built 2 observatories there . His observatories contained costly

equipment that Tycho Brahe built himself . From these observatories

Tycho studied stars for more than 20 years . He observed the positions

and motions of stars , moon and planets every night without fail .

He would note down all the data with extreme accuracy . His instuments

were very precise too . No one before him had ever studied the heavens

with so much accuracy . And he did all that with his naked eye . The

telescope had not been invented yet !! He singlehandedly established

the observational basis of astronomy .

 

      Tycho almost made a observational factory on that island . He

employed a huge number of people to help him . The instruments were made

there . He also had a printing press to print books about his

observations .

 

      His obrevations were studied by Kepler and he found a pattern

and he formulated his 3 laws of Planatary motion . Keplers 3 laws

were used by Newton to make this Theory of Gravitation .

Tycho’s observations were also used by Halley to discover his comet .

He made an observation of Supernova in 1572 . His observation’s were

used by modern astronomers to form a theory about how stars die .

 

      The greatest thing about him was that if you look at his works

you would find observations of every star for every night for those

22 years . And these positions will be extramely accurate . And

it makes you admire his dedication to his work . Did this guy ever

go to late night parties !!! he probably never slept at night for those

22 years . And this dude didnt even have a telescope !!

 

His observations are still used today by modern astronomers .

 

      The works of Tycho have been compiled in  15 volumes under the

title “Tychonis Brahe Opera Omnia”     

Incas

The Incas were a fierce warrior tribe that ruled Equador to central Chile between 1200 and 1535 AD .

 

The architecture of the Incan cities amazes scientists . They built their cities on the steep sided of the Andes Mountains . The cities had stone steps leading upto them and the building blocks were massive blocks of stone . These stones were so tightly fitted together that not even a blade could pass between them .

 

The Incas had a very strong hierarchial structure in their society .

The Sapa( priest ) , the ruler were at the top . Then were the councilors. After that came temple priests , regional commanders . The lowest level were farmers , workers etc . Even women could rise to the top and could occupy any position .

 

They developed a system of irrigation and this led to surplus food .

The Inca population prospered and grew . The Incas had a great army .

They build strong fortresses on the tops of mountains . The most famous Incan fortress is at Sacasahuman located at the Incan capital Cuzko .

 

The Incas also had a complex religious system . They worshiped the animal spirits and had complex religious rites. In Incan paintings the heaven are depicted by the Condor , the underworld by the Puma .

The incas also hhad a elaborate calendar.  The sun temple( remember Tintin ) in Peru had the calendar inside it .

 

The Incas were very cruel people . The punishments were very severe .

They didnt have any prisons . Why ? because all punishments were by crusl deaths . Culprits were thrown off mountains , or had eyes , hands removed etc . They didnt need prisons .

 

The 40,000 memner Inca army was destroyed by the Spanish Army . In 1535 the inca sociaty was wiped out . One of the reason of the destruction of the Inca society( according to Discovery Channel ) was that when the Incas came in contact with the Spanish they also came in contact with bacteria/virus which the Europeans brought with them . The Europeans were immune to these virus . But the Incas had no defences . Epidemics caused the Inca society to perish . This also shows the destructive power a new bacteria/virus can have on a different/new population .

Gravitational Lenses

If you remember your high school Physics u would know that a lens bends light and this phenomenon can be used to form various kinds of images.

Lots of interesting images : real and virtual and all that . All because a lens can bend light .

 

 Einstein showed ( in his General Theory of relativity ) that

Gravity can also bend light . So can a large body bending light due

to its gravity also act as a lens ? Of course ! These lenses are

called gravitational lenses

 

      So imagine ( dont just sit there . Draw ! ) a radiating star/quasar

behind a galaxy and then there is the Earth . The light from the

star is bent by the galaxy and then reaches the earth . So the

star appears at a different position from where it actually is .

 

      Also since different parts of the galaxy bend light in different

directions we can see the same star at multiple places. Multiple

images of the same star/quasar .

 

      So the system kinda looks like this :

 

 

   S’

 

 

   S              G                       E            

 

 

   S’

 

 

 where :

 

 S : is the orignal position of the star

 S’: are the images of the  same star S

 G : is the galaxy that bends light due to its gravity

 E : Earth ( the place from where we observe )

 

 

  Many times we see a 4 images of the same object ( called Einstein Cross )

 

  Gravitational lenses can be used to detect previously unknown objects ,

   determination of Hubble’s constant ( rate of expansion of the universe ),

   finding out the size of galaxies( lenses )

 

 

  Now look at some very pretty images of some gravitational lenses .

  Yeah ! do it . otherwise there is no point :

 

 

   http://csep1.phy.ornl.gov/guidry/violence/gravlens.html

 

   http://www.tu-harburg.de/rzt/rzt/ts/pictures/stsci/glc_homepage.html

 

 

   Look for objects that appear more than once in these pics .