Its been a great pleasure for us to work on this magazine. We started Science Panorama for a reason, and bringing out this magazine has strengthened our goals to work more on new ideas. When you try something different like giving out the magazine or ebooks for free, you're asked why? My honest answer would be that a few days ago when I wanted things like this magazine, ebook or something interesting no one wanted to share them for free. All wanted us to pay for a genuine version of something we wanted. When I was working as a photographer at Physics de Pristine, Mayukh brought up the idea of magazine. But the problem was that no one was interested in moving it further because the version of magazine Mayukh had made needed a lot improvement before it was presented before someone, But it was creative and the idea of being layman was very well portrayed. He spoke about the idea before me in a casual Facebook chat. I opted to help out and thought that he had a great idea. We made the magazine and asked people to subscribe and We sent the magazine to all those who had subscribed through email. We couldn’t upload it live as we did not have a website that could feature it, Also I wasn't satisfied with what we had done cause as the name read the ideas did not reach everyone. It reached only to those who had subscribed. When we shared the ebooks at our website, we faced some criticism about it and some said if we were really passionate about sharing knowledge then why not write our own book and give it out. Then it flashed to me, We already have a magazine that not many people have read and we could share it again. But this time we decided to include more articles and make people participate in it by contributing photos or any art they had. I designed the cover photo overnight and asked my team's opinion and put it live before you people. We had to juggle between our studies and work at Science Panorama but in the end here is what you have been waiting for and we have been working day and night to bring it before you. We have tried our best in eliminating all errors we could but given that we are students and are learning some errors might have inadvertently crept in. Please bring it to our notice if you find any. Thanks to all at Physics de Pristine who helped us to bring out this magazine. And a hearty thanks to Mayukh for making me believe every time that we were doing great at the magazine. Lastly but most importantly its you people I have to thank the most for supporting us in what we do and filling us with your love. -Vidyadhar Sharma Chief Editor & Designer, WIRE
Can Physics be the Secret to Artificial Life ? This article is a collection of
thoughts on the principles of entropy, energy and equilibrium expressed in the context of self assembly of surfactant
hates water as shown in the cartoon alongside. What "loves" means in the following is that the entity can lower its energy by being in contact with water.
Equilibrium conditions
molecules . Let us begin by asking what a surfactant is. For the purposes at hand, a surfactant is a molecule with a small head that likes water and a long tail that
the system will like to do, we need to know one more thing about the surfactant molecules. If two surfactant molecules come close to each other, what would they do? The tails of these molecules are such that they are happiest when they are as close to each other as they can get, for they lower their energy by reducing their interaction with water and increase their entropy as well. The heads of these molecules are such that they want to stay as far away from each other, because these heads are usually charged and like charges repel right? So they lower their energy by staying away from each other contact with water and what "hates" means is that it costs the system a lot of energy when it is in contact with water. Now, we put a bunch of these surfactant molecules in water and allow them to come to "equilibrium". What do they do?
To understand this question, we have to first clarify what a system will like to do. The equilibrium state of the system will be one where it can do the maximum number of things it likes. The first thing the system likes to do is lower its energy as much as it can. On the other hand, the system likes to have as much disorder as possible, technically speaking, "maximize its entropy". If I call the energy of the system E and the entropy of the system S, then the system likes to have a minimum value for the quantity F = E - TS, and this is called the free energy of the system. Don't let this little jargon Micelles = self assembly scare you. What follows is structures simple enough even if you With that, we have all the don't remember this. Also, ingredients we need to before we can guess what
answer the question we asked. It is now all about a competition between love and hate. Suppose the heads love water way more than the tails hate it. Then the equilibrium state of the system will be a solution of the surfactant molecules in water, with all the molecules well separated from each other and doing their own thing. Next, suppose the circumstances are that the hate of the tail wins. Also, suppose that the heads are wide objects so that the overall shape of the surfactant molecule is a cone (see figure). Then, the molecules are happiest when they form micelles. Micelles are objects that are spheres, with the polar heads outside near the water and the tails inside, talking only to each other and protected from the water by the polar heads.
Bi-layers Note that, in order to form micelles, you need a given amount of surfactant in the water (If you have fewer surfactant molecules, entropy wins and they stay in the form of the solution). The everyday situation under which micelles are formed is when you wash your clothes with soap. The
dirt on the clothes form nucleating centers for the micelles and the micelle itself being water soluble, dissolves in the water when you rinse your clothes.
The more interesting case is when the heads are not fat, i.e., the surfactant molecule is a cylinder rather than a cone (see figure) and still the hate of the tails wins. In this case, the system forms what are called "lipid bilayers". This is just two layers of surfactant molecules assembled such that the tails of each layer face each other (effectively, it is like having a layer of oil trapped between two layers of polar heads). Now, in this structure, the tails in the middle are clearly happy for all their neighbors are fellow hydrocarbons. But, just as clearly, the tails at the edge of the structure are
unhappy because they have to talk to the surrounding water. One way to eliminate this is for this bilayer to fold on itself to form a spherical shell (see figure, which displays a cross section of such a structure). This way, there is no surface of tails talking to the water. But the trade off comes at the cost of forcing the heads in the inner layer to be more close to each other than they like. But, if the hate of the tails for water is large enough, this happens and the resulting stable structure is now a vesicle! CONCLUSION The interesting things to note here are two fold:
1) In spite of the language I am using, in the actual experiment, all we did was take a spoonful of surfactant molecules and put it in water. All the structures mentioned above self assembled! we
did not have to do a thing. 2) The second thing to note is that, the above vesicle is essentially a minimal cell membrane, the first step towards the process that converts an auto catalytic chemical reaction into what we call
now as life! So, if we can make this membrane functional, namely, make sure that the chemical machinery required for life is trapped inside the vesicle, make appropriate "holes" so the membrane is suitably permeable (i.e., it lets some stuff in (raw
material for making food) and some other stuff out (waste products) and not vice versa), we would have made an artificial cell! Some first steps in this direction have already been taken. We are not very far from what can be termed as artificial life.
So, we can very well perceive the vast scope of physics that can make such valuable contributions even in the field of artificial life synthesis. I would like to end this article with this quotation that i readily believe can explain the enthusiasm of all physicists to learn about nature in one go : "The scientist doesn't study nature because it is useful; he studies it because he takes delight in it, and he delights in it because it is beautiful. If Nature were not beautiful, it would not be worth knowing, and if Nature were not worth knowing, life would not be worth living." -Henri Poincare
Did you know? • Marie Curie was the first person to win two Nobel Prizes for Science. • No one has received more U.S. patents than Thomas Edison – 1,093 to be exact. • Telecommunications satellites, and other satellites that need to maintain their position above a specific place on the earth, must orbit at 35,786 kilometers and travel in the same direction as the earth's rotation. • The Ericsson Company first produced cellular phones in 1979. • The Internet is the fastest-growing communications tool ever. It took radio broadcasters 38 years to reach an audience of 50 million, television 13 years, and the Internet just 4 years.
Albert Einstein
Part 1
as when he went up! (however such a thing becomes noticeable only if the rocket traveled with speeds approaching velocity of light) The arguments in Dr Einstein theories look like long abstract philosophical dialogues some times quite bewildering confusing and uninteresting but soon transform into tough challenging scientific theories supported by superlative mathematical working and these theories and predictions of Dr. Einstein were proved to be accurate and correct by other As for the man , photos of his old age deceive experimental scientists. though he has such a rare glint in his eyes. He looks very much a simple old man of gentle Towards end of 19th century scientists were manners and childish smiling ways. But he is already feeling dissatisfied with existing theory one of the greatest intellects of all time. People of electromagnetic radiation though it most of science enjoy discussing who among the beautifully explained many phenomena in two, Sir Issac Newton and Dr Einstein is the optics, electricity and magnetism.. The greatest? Both are sky high mountains of Quantum theory of Dr Max Planck completely intellect simply awe inspiring. Peculiar stories broke with the wave theory to explain certain exist about situations that may result from his anomalies in “black body radiation” . the theories. theory proposed , against all existing time (1) A measuring stick carried in a journey tested rules, that heat energy is radiated in becomes shorter and shorter as the speed of fixed size packets called quanta and not in journey increases. so measurements with same form of continuous em wave. Dr A.A. stick while sitting in a room on earth would be Michelson's experiments gave results that did different from the measurements taken using not support existence of the mystical aether. it in a imaginary journey by a fast jet plane ! There was no way to explain the existence of ( however this difference would become electron, radioactivity (undiminished release of noticeable only at speeds approaching velocity energy from inside atom against the principle of light which is 300,000 kilometers per of conservation of energy) and x radiation on second). the basis of Newton’s and Maxwell’s physics. It
A
student of physics feels quite a thrill when he studies the work of the great Dr. Albert Einstein who overturned almost the entire set of scientific theories of physics based on classical mechanics of Sir Issac Newton and Dr. Maxwell’s theory of electromagnetic radiations reigning supreme at turn of 19th century by publishing four outstanding research papers in the German scientific journal Annalen der Physik in 1905.
(2) Among two twin brothers born at the same moment let one of them stay on earth and let the other travel for forty years in outer space in a space rocket. The man living on earth becomes an old man while the brother who went up in space rocket stays almost as young
is quite unbelievable to note that even by the year 1900 most scientists were not ready to believe in the existence of atoms and molecules and treated them as nothing more than useful theoretical concepts. -Sastry Polavarapu
Photographic learning
“I was amazed after knowing how geniuses were the ancient Indian astronomers! Our earth taking the moon orbits around the sun. The sun taking all the eight planets, asteroids and comets orbits around the center of the Milky Way. In that sense the Center of the Milky Way is the native (“mool” in Hindi) where all the stars of the Milky Way orbits around. Modern science knows this fact in recent times whereas the ancient Indian astronomers knew this fact thousands of years ago! That’s why they’ve named this part of the sky as “Mool” means The Native or The Nucleus. Isn’t this surprising?” says Rahul.
One of the greatest contributors to the field of science!
Werner Heisenberg (1901-1976), German physicist. Heisenberg was a founder of quantum physics, being awarded a Nobel Prize in 1932 for his matrix mechanics version of the theory of quantum physics. He developed the Uncertainty Principle in 1927. This stated that the more precisely the position of a sub-atomic particle is measured, the less precisely its momentum is known. This removed absolute determinacy (cause and effect) from physics, replacing it with statistical probability.
NUMBER OF STARS IN ENTIRE UNIVERSE After seeing an interesting article in Net I made a small calculation. I found I could place thirteen sand grains on a cm length. So number of sand grains in a cubic cm volume is 2197 or 2200. Let us imagine a big sand bar “10 kms long, 10 meters wide and one meter high”. Its volume comes to “10 power13”cubic centimeters. Number of sand grains in this big sand bar is --[22 multiplied by “10 power 13”].Let us indicate it by P Number of galaxies in total universe (not simply the observable universe but entire universe)as envisaged by astronomers is a minimum 200 billion . As per the astronomers each galaxy can contain a minimum of 200 billion stars(i.e. 200 billion suns like our own sun!) So total of STARS in entire universe is--[ 4 multiplied by “10 power 22”] .Let us indicate it as Q. Q /P gives 0.18 billion or nearly 200 million! The comparison between the hugeness of universe and the smallness of a star is simply benumbing. Let us imagine a sand beach ,as mentioned above, of [100 km length,10 meters width and one meter high ]. Number of stars in universe is 200 million times the number of sand grains in a "100kmx10meterx1 meter" volume! Even if we travel at 50,000 kmph nonstop in present day rockets it takes 100,000 years even for a one way journey to reach even the nearest star of our own galaxy. Let us not lose heart because of the belittling fact telling us that we can
not reach not even one star,not even the nearest star. We can at least realize earth’s precarious position and form an idea about position of earth in universe .( However earth is very very very stable. It is most smoothly sailing in the void for billions of years without disturbing a grain of sand )We have a most beautiful earth with beautiful cities .Earth has a golden future. If only we harshly reverse the dangerous trends in nuclear armament proliferation,environmental pollution, plastic pollution,chemical pollution,carbon pollution etc(all caused by the stupid humans) we can still ensure safety to all living beings for the next 1000 years.(By then we may be able to find methods to accumulate oxygen,hydrogen,carbon etc in sufficient quantities to provide environment for earth like life to flourish and be able to construct underground colonies on of planets of our solar system or to create space cities each with a million population for ever circling in solar system in orbits around planets and freed forever from shackles of earth’s gravity!) . Add to the above the dangers population, explosion and illiteracy and earth looks like a leaky boat left unprotected and drifting on the high seas. We have got to put the population map on a steeply declining course. Humans are not the only inhabitants of this earth. Scientists are there to take care of all these things. So do not loose heart -Sastry Polavarapu
Think Physics This Section will contain Interesting facts
or questions by our members. Think about
these questions and try to answer them. If you have any questions regarding physics then write to us at info.sciencepanorama.com with your name and we will ask those questions in our next issue.
• A fact we all know, like charges repel and unlike charges attract... But what's the reason for this? -Mohammad Hadi. Does negative mass exist ?If yes, then according to you, where this negative mass should fall..?? Is it downward or it should go upward ? •
-Sanjesh Chauhan. If the universe is expanding according to the big bang theory, then why is the distance between all the planets and the sun in the solar system and between galaxies is the same? •
- Mitesh Vora. What happens to the mass (energy) of the object when it goes into the blackhole ? •
- Akshay Gs Why an electron and a proton have same amount of charge even though their masses are different? •
-Aditya Adi
If you think you have the answer for these questions then share and discuss it with others at www.facebook.com/physicsdepristine
LET THERE BE MORE LIGHt The prevailing view of the nature of light has
Clerk Maxwell. Maxwell’s equations describe
changed several times in the past three
light
centuries. We could also safely say that there is
electromagnetic field surrounding a charged
surely no branch of Science more ancient than
particle, the variations in the field being
the study of light. Each time the answer to the
generated by the oscillations of the particle.
question, “What is light?”, has assumed more
Thus, in Maxwell’s theory, light appears not as
fundamental
an independent element in nature, but rather,
importance
in
the
physicists’
picture of the Universe.
as With the Greeks, and
later
Minds
like that of Isaac Newton,
in
his
work, Opticks, in 1704
described
light as a stream of particles “because it
travels
in
a
straight line” and associated the wavelike properties with light beams which he called “ fits of easy reflection and transmission”. He was careful not to make any hypotheses and let the matter rest. Then came the notion that light consists of waves, early in the 19th century, with views already expressed by Christian Huygens in the 17 th century and confirmed a decisive experiment performed by Thomas Young in 1803, who said that when a monochromatic beam of light passed through two pinholes, it would setup an interference pattern that resembled those observed in “the case of waves of water and pulses of sound.” The elucidation of the wave nature of light fit nicely into the electromagnetic theory of light propounded later in the century by James
as
an
a
rapid
aspect
variation
of
the
in
the
fundamental
phenomenon. ELECTROMAGNETISM: The momentous developments in Physics in this
century
have
re-opened
and
then
resolved the old wave-particle controversy. Whereas,
the
association
of
light
with
electromagnetism is valid, the interpretation of this connection has changed. It has been shown that wave properties such as interference and polarization, so well demonstrated by light, are also exhibited under suitable circumstances by the subatomic constituents of matter such as the electrons. Conversely, it has also been shown that light, in its interaction with matter, behaves as though it is composed of many individual bodies called photons, which carry such particle-like
properties
like
Energy
and
Momentum. As a result of these developments, most Physicists today, would answer the question “What is Light”, as Newton would have said: “Light is a particular kind of matter.” The differences between light and bulk matter are
now
thought
inessential
to
flow
differences
constituent particles.
from
relatively
between
their
example: A photon of blue light has an
Particles of all kinds
energy of about 3*10^(-19) Joule; which
exhibit wave properties. An
important
step
corresponds to a wavelength of 4*10^(-7) in
establishing
the
underlying resemblance of the particles of matter
to
particles
of
light
was
the
recognition that for both kinds of particle, wavelength is related to momentum, and hence
to
the
It can further be elucidated by the following
energy
of
the
particles
constituting the beam. It is shown that the wavelength is inversely proportional to the
meter. If this photon energy is transferred as Kinetic Energy to an electron, which starts with a rest mass energy of 8*10^(-14) Joule, the total energy is changed very little( by less than
ten
parts
in
a
million)
and
the
wavelength is about 10^(-9) meter. The wavelength is still shorter of course, for particles with larger rest- mass energies.
momentum. In the case of an electron, the
The fact that even I would have an associated
energy must include the rest mass of the
wavelength when I am running at my top-
particle. Photons, on the other hand, have
speed has always intrigued me. This means
zero rest mass, and so the term for rest mass
that even I am a part of the broad electro-
drops out of the equations. We are now, on
magnetic spectrum of Light!! And possibly
the verge of answering the question: Why is
one day the electrons in the atoms of the
the wavelength associated with an electron
millions of cells in my body could be given a
shorter than the wavelength of the light
momentum transforming me into a beam of
beams
LIGHT!! Might as well be dismissed as day-
(or
wavelength
associated
with
photons)?
dreaming for now, but haven’t such vague
It is the rest-mass energy (E=mc^2) of the electrons and for that regard any other matter particles that gives them wavelengths so
musings given rise to some of the most interesting discoveries in the history of mankind??
much shorter than the light beams.
-Sireesha Vangala
Get Inspired! “If People are good only because they fear punishment, and hope for reward, then we are a Sorry lot indeed!� ~Albert Einstein.
The Rise and fall of Theoretical Physics - Abhas Mitra
In the first part of this article, I shall briefly
observations overthrew the classic
describe the birth and rise of ``Theoretical
based Aristotlean world views to herald modern
Physics’’, from a somewhat historical perspective.
physics. For instance, Aristotle had argued that
It is warned at the outset that this description will
the orbits of heavenly bodies must be circular
be extremely sketchy and far from comprehensive.
because circle has a perfect symmetry. But
Further, the emphasis here will be on ``Theoretical
observations showed that such orbits in general
Physics’’ rather than ``Mathematical Physics’’.
are elliptical. To be more precise, Isaac Newton
Physics
as
a
subject
concerns
observation,
understanding and prediction about the physical world. It is different from mere philosophical or spiritual or religious understanding. In a sense, it is an evolved and more analytical form of Natural
Sciences studied in the pre-Newtonian era. And ``Theoretical Physics’’ is the basic framework for understanding and predicting physical phenomena in terms of well defined premises, laws in analytical form. Thus although ``Theoretical Physics’’ may involve various mathematical formulae or tools, it is not mathematics in itself. On the contrary, ``Theoretical Physics’’ originates from observations and experimentations of physical phenomena, and it could even be able to predict unknown physical effects. The success of ``Theoretical Physics’’ (TP) lies in the verifiability of its predictions.
philosophy
(1642–1727), guided by Kepler’s laws of planetary motion, predicted an universal law of gravitation. He was also influenced by Galileo’s experiments, and probably, ``Theoretical Physics’’ as a matured subject was born on July 5, 1687 when Newton published "Mathematical Principles of Natural Philosophy", often referred to simply as the Principia. While formulating his physical theories, Newton developed and used Calculus. However, one hardly needs to emphasize the fact that calculus itself is no physics or science. Neither any mathematics nor any geometry by itself is physics even though they may provide the language for formulating TP. Once Galileo and Newton formulated the classical physics, it grew with inputs from many greats. In
Indeed the birth of TP may be related to the
classical
improved facility for observations or technological
important law of elasticity,
developments. It might be seen that, there was hardly any TP, say 400 years ago. Following this
Robert Hooke
physics,
the
that the restoring force is proportional to displacement,
vacuum, even without using telescopes, Tycho
was given by Robert Hooke(1635–1703) in 1960.
Brahe (1546–1601) made accurate observations of
However, while Newton considered light as a
planetary motions and many other astronomical
collection of point particles even at the classical
phenomena like Supernova Explosion. Based on
level, it was Christian Huygens (1629-1695) who
such observations Johannes Kepler (1571-1630)
correctly predicted the wave nature of the same in
published his laws on planetary motion during
1678. Also, it was Huygen who first got the laws of
1609-19. Such laws, in conjunction with Galileo
motion for an oscillating pendulum. Later, William
Galilei’s
Rowan
(1564-1642)
telescope
based
Hamilton
(1805-1865)
reformulated
classical mechanics in 1833 by the Principle of The
Least Action, a method known as Lagrangian Mechanics. This was based on Analytical Mechanics and variational calculus developed earlier by Joseph Louis Lagrange (1736- 1813). The concept of ``Lagrangian’’ and ``Hamiltonian’’ proved to be important milestones not only classical mechanics but also for entire TP whether it is quantum physics or relativistic physics. The variational principle used in the Lagrangian and Hamiltonian formulations were originally due to Pierre de Fermat (1601 -1665) and Pierre Louis Maupertuis (1698-1759). In particular Fermat had postulated that “light travels between two given points along the path of shortest time ”. It is interesting to note that the Snell’s Law of refraction of light rays, obtained by Willebrord Snellius (1580–1626), follows from the principle of least action/time. Amalie Emmy Noether (1882-1935) introduced by her name in 1931. The Noether a theorem’s Theorem explains
the
fundamental
connection between symmetry and conservation laws in all realms of TP. Note, Emmy is probably female Amalie Emmy Noether
and
the
best
known
theoretical physicist
mathematician
in
the
history.
The basic structure of massive self-gravitating astrophysical objects, such as stars and galaxies, is described by the so called Lane-Embden equation which was independently obtained by Jonathan Homer Lane(1819 -1880) in 1870 and Jacob Robert Emden(1862– 1940) in 1907. The Navier–Stokes equations of fluid motion, important for many areas of physics too, was developed by Claude-Louis Navier(1785-1836) in 1822 and George Gabriel Stokes (1819- 1903) in 1850.
phenomenon
of
static
magnetism
and
electricity have been studied since antiquity. And based on such observations and not from just
intellectual speculation, Charles Coulomb (17361806) published the inverse square law of static electricity, known by his name, in 1785. Of course whether it is Newton’s or Coulmob’s law, they all have been verified by various observations and experimentations. Few decades before it, in 1752, Benjamin Franklin’s (1707-1790) observations had already opened up the subject of electric currents. There were observations suggesting intimate connection between of electric and magnetic phenomena, and the experiments of Hans Christian Ørsted(1777-1851) and André-Marie Ampère (1775-1836) gave birth to the subject of electromagnetism during 1819-1820. Following this, Michael Faraday (1791 -1867) not only invented the electric motor in 1821 but also developed the concept of an electromagnetic field. The ultimate unification of ``electricity’’ and ``magnetism’’ as well as the realization that light was a form of electromagnetic wave can be ascribed to James Clerk Maxwell (1831-1879). His laws formally got announced in 1865. This was the culmination of the classical phase of the modern physics, and much of the fruits of this epoch making discoveries were put to use for the benefit of human kind by the researches of the great technologist Nikola Tesla (1856-1943). Maxwell’s equations were however ignored by many peers for a long time; one of the reasons for this was that Lord Kelvin (1824- 1907), one of the most influential British physicists of those days, was a staunch believer in the existence of ``aether’’ and was rather conservative about new physics and technologies. After Newton, Johann Carl Friedrich Gauss (1777-1855)
is
mathematicians
the of
best the
example highest
of
how
order
can
contribute to the pioneering development of
by
about an absolute zero of temperature. By armed
mathematical
with the laws of conservation of energy and
physics, say in the field of Quantum Gravity, which
Newtonian gravitation, Helmholtz and Kelvin
rarely make any verifiable prediction. In 1835, Gauss formulated ``Gauss's law’’ relating the distribution of electric charge to the resulting electric field. This however got published only in 1865 as one of the ingredients of the Maxwell’s Equations of electromagnetism.
independently developed one of the fundamental
A very important parallel development of classical
(H-K Process).
Theoretical
Physics
experiments unlike
which
are
present day
testable
physics and TP had also been in progress. Thomas Newcomen (1664-1729) had developed a commercially successful model of Steam Engine in 1712. And James Watt (1736 – 1819) invented a qualitatively superior version of the same during 1762- 1775.
This
and
other
associated
technological big leaps gave rise to Industrial
Revolution (1750-1850) in Europe. As the scientists wanted to understand the functioning of new machines and improve their efficiencies ``Thermodynamics’’ got developed as a subject. The concept of Carnot Cycle came in 1824 following the experiments by Nicolas Léonard Sadi Carnot(1796 -1832), and then Rudholp Clausius (1822-1888) formulated the 1 st and 2nd laws of thermodynamics in 1850. And it is he who introduced the concept of entropy in 1865. Further in 1870, he found ``Virial Theorem’’ which connects the potential and kinetic energies of a fluid. A crucial aspect of 1 st law is the concept of ``mechanical equivalence of heat’’ was developed by Julius von Mayer (1801-1869) and James Joules (1818-1889) during 1840-1843 through a series of experiments. Such experiments and the development of thermodynamics led Hermann von Helmholtz (1821-1894) to formulate the Principle of Conservation of Energy. In 1871, Helmholtz also announced that the velocity of the propagation of electromagnetic induction was about 314,000 meters per second! As to the 3 rd law of thermodynamics, Lord Kelvin first spoke
aspects
of
Theoretical
Astrophysics
in
the
nineteenth century: A self-gravitating fluid, during its contraction, not only becomes hotter but also must radiate out part of the released gravitational potential energy
The birth of Statistical Mechanics can be largely attributed to the physical intuition of Ludwig Boltzman (1844-1906). By 1988, he was a very well known physicist and even became a Fellow of the Swedish Royal Academy of Sciences. It is after this period that he developed atomic theory of
heat. He along with James Maxwell gave the Maxwell- Boltzman distribution formula of speeds of atoms in a gas. However most of his peers wanted to see ``heat’’ only as a form of energy and were not ready to attribute microscopic molecular motions to it. This was one of the reasons which drove Boltzman to mental depression, and he leapt to his death into the Adriatic sea at Trieste on Sept. 05,1906. His tombstone bears the inscription: S=k ln W! Ironically, the spot where he committed suicide is adjacent to the International Centre for Theoretical Physics (ICTP). The spectrum of a black body radiation, being studied experimentally since 1850, could not be explained
by
a
single
theoretical formula. In 1900, Max offered
Planck the
theoretical
(1858-1947) much
needed
platform
by
introducing the revolutionary concept that radiation can be seen as sum of discrete quanta
Max Planck
whose
energies
are
proportional to the frequency of the radiation. transformations were already due irrespective of However, historically, Boltzman had suggested in Michelson – Morley null results. And this was 1877 that, in a physical system, energy can appear probably first realized by Jules Henri Poincaré in discrete values. Formally the concept of a (1854 – 1912). He elevated the proposal of ``Lorentz ``photon’’ as the quanta of radiation was further – Fitzerald Contraction’’ into a revolutionary new developed by Einstein in 1905 while explaining the complete coordinate/velocity transformation law, phenomenon of ``Photo-electricity’’ discovered in i.e., ``Lorentz Transformations’’. As he showed that Philipp Lenard 1902. Formally, the term "photons", Maxwell’s equations are invariant under the new was however introduced by Gilbert N. Lewis transformation law, pre-natal phase of Special (1875-1956) in 1926. The old form of Quantum Theory of Relativity (STR) was born. Incidentally, it Mechanics (QM) came into being in 1913 as Niels was
called
``special’’
because
the
relevant
Bohr (1885-1962) offered a model of atoms where transformations were thought to be applicable only electrons revolve the central nucleus in orbits for inertial frames. The fact that physical laws must having quantized energies. The Bohr model was a be
invariant
under
appropriate
coordinate
quantum improvement of the model of atomic transformations, in other words, the principle of nucleus offered by Ernest Rutherford (1871-1937) relativity was laid down by Poincare. He made such just two years earlier. Bohr’s research is a very presentations to the Academy of Sciences in Paris important in TP contribution because it correctly on 5 June 1905. In fact the most famous equation explained the spectral lines of the hydrogen atom. of physics E=Mc2 first appeared in Poincare’s Accordingly, Bohr won the Nobel prize for this manuscript. successful model/theory in 1925. To
see
the
close
Further Emil Georg Cohn (1854 – 1944) also
relationship
of
TP
with
published two papers in 1904 whose title
observations and experimentations, we may recall
contained the phrase ``electrodynamics of moving
the Michelson–Morley experiment performed in
bodies’’, and derived most of STR. However, Cohn
1887 by Albert Michelson (1852-1931) and Edward
thought that Lorentz Transformations had validity
Morley (1838-1923). It was designed to detect the
only for optical phenomena.
relative speed of Earth with respect to the aether. The
null/negative
result
of
this
experiment
suggested that the speed of light in the vacuum is constant and vacuum is actually not filled with any mythical fluid, aether through which light waves were
supposed
to
propagate.
This
result
challenged the Galilean Relativity, and in order to explain this null result, in 1895, Hendrick Lorenz (1853-1928) proposed that moving bodies contract in the direction of motion.
Such a Length
contraction was already postulated by George Francis FitzGerald
(1851-1901) in 1889. Actually,
Maxwell’s equations of electromagnetism obtained in
1965
are
not
invariant
under
Galilean
Transformation, and thus new laws of coordinate
Yet, STR, as a fundamental and complete physical theory, was developed by Albert Einstein. His paper
``On
the
Electrodynamics
of
Moving
Bodies’’, submitted on June 30, 1905 and published on September 26, 1905, is the true thesis on STR. To Einstein, the phenomenon of constancy of the speed of light was not just a result of Michelson –Morley experiment, nor just a consequence of Maxwell’s electromagnetism, but on the other hand, a fundamental law of the Physical World. Accordingly, he independently considered ``Principle of Relativity’’ a fundamental all encompassing fact of Physics. By basing on these two fundamental postulates, he arrived at the Lorentz Transformation formulae. While the
E=Mc2 formula found by Poincare was only in the
relativistic
context of electromagnetic waves, the same for
geometrically
Einstein was a fundamental equivalence of ``Mass’’
somehow, by some historical mistake, it is referred
and ``Energy’’. Einstein’s paper announcing STR
to
did not cite a single reference, an act, which would
gravitational mass of a star or galaxy, appearing in
be castigated by all modern science journals!
this solution must indeed be positive and finite.
While Poincaré too questioned the concept of universality, but contrary to Einstein, he continued to use the concept of aether in his papers. His contention was that the clocks in the ether show the "true" time, and moving clocks show the local time. In effect, Poincaré tried to keep the relativity principle in accordance with classical concepts, while
Einstein
developed
a
mathematically
equivalent kinematics based on the new physical concepts of the relativity of space and time. Thus, Einstein was the real founder of STR. It became soon clear that Newtonian gravitation was inconsistent with STR, and after a long struggle and several false starts, and also help from various quarters, in particular from the mathematician Marcel Grossmann (1878 -1936), Einstein arrived at the correct form of General Theory of Relativity (GTR) in 1916. This was now called ``general’’ theory because it was applicable to all frames. The central equation of GTR, called, Einstein Equation, proposed that the geometry of the 4-D space-time continuum (tensor) is directly generated by Matter Energy Momentum (tensor). As far as the mathematical derivation of Einstein
Equation is concerned, the mathematician David Hilbert (1982-1943) derived it by elegant variational principle almost simultaneously. In other words, gravitation is the manifestation of space-time structure. Some of these experimental verifications of GTR have been based on the solution for the space-time structure around a neutral ``point mass’’ (massenpunkt) by Karl Schwarzschild (1873 -1916) and David Hilbert (1862-1943) which differ by the choice of the origin of the radial parameter. While modern
as
astrophysics
the
correctly
significant
use
``Hilbert
``Schwarzschild
the
solution’’,
Solution’’!
The
However, in 2009, it was shown (A. Mitra, Journal of Mathematical Physics, Volume 50, pp. 042502: http://arxiv.org/abs/0904.4754) that, for genuine point mass (and not for a finite object) , the gravitational mass would shrink to zero due to loss of mass-energy during prior shrinking of say, a star. Nonetheless, the ``Black Hole Paradigm’’ is based by ignoring this fact, and instead by adopting the Newtonian notion that even a point particle can have arbitrary high mass. It is now widely acknowledged that GTR is the most selfconsistent
and
beautiful
physical
theory
humankind has ever formed. Esthetics apart, GTR has passed most of the experimental tests carried out so far to cross-check it, and definitely scores well
above
several
other
relativistic
gravity
theories proposed from time to time. Such alternative theories often have additional/ ad-hoc assumptions and lack the beauty and simplicity of GTR. The only ad-hoc element added to GTR is the so-called ``Cosmological Constant’’ introduced in 1917. However, ``Cosmological Constant’’ is badly needed only by the presently popular (19982012), ``Concordance Cosmology’’ which could very well be incorrect. And it is well known that, in his later years, Einstein himself wanted to do away with this ad-hoc constant. Talking about Poincaré, it must be mentioned that he was
also the first scientist
to discover a
chaotic deterministic system and which would be the foundations of
modern chaos theory,
applicable for most of the physical systems having multiple degrees of freedom and in particular for complex systems. Though this article is about TP, I cannot resist here telling the fact that Poincare is
the
founder
of
the
mathematical
subject
Sommerfeld (1868 -951) was one of the pioneers
``Topology’’, and that proposer of the ``Poincare Conjecture’’ of mathematics.
of atomic physics by using the Fermi-Dirac
The concept of quantum mechanics took a new
statistics and gave the concept of a Fine Structure
Constant.
and interesting turn in 1924 with the postulation
Relativistic Quantum Field Theory, the theory that
of wave-particle duality by Louis de Broglie in his
unified STR and QM, got developed with the
Ph.D. thesis; and in the same year, the phrase
publication of theory of electrons (spin half
"quantum mechanics"was first used by Max Born (1882-1970) in his paper "Zur Quantenmechanik". Modern QM however was born, so to say, in 1925 when Werner Heisenberg (1901-1976), Max Born and Pascual Jordan(1902 -1980) presented its Matrix Formulation. In the following year, Erwin Schrodinger (1887-1961) revolutionized physics by publishing the wave equation for a quantum system. In the same year, Enrico Fermi (1901 -1954) and Paul Dirac (1902-1984) independently gave ``Fermi–Dirac statistics’’ applicable for identical particles with half-odd-integer spin in a system in thermal equilibrium. On the other hand, in 1924, Satyendra Nath Bose (1894-1974), in collaboration with Einstein gave Bose–Einstein statistics, applicable for integer spin particles. And this discovery paved the way for the theory of the Bose–Einstein condensate. By 1925, Wolfgang Pauli (1900 -1958) suggested the Exclusion Principle, known by his name, by which two Fermions are prohibited to occupy an exactly same quantum state. A natural consequence of the wave particle duality was perhaps fuzziness for the precise location of a R.H. Fowler particle. And this was highlighted by the ``Uncertainty Principle’’ by Heisenberg in 1927.
particles) by Paul Dirac in 1928. This theory also
A truly path breaking application of the Pauli
2005) developed the theory of nucleo-synthesis, in
exclusion principle was made in 1926, when Ralph
particular, carbon-oxygen-nitrogen cycle , in the
H. Fowler (1989-1944) showed that the compact
core of Sun like stars. The traditional H-K process
White Dwarf stars could be supported by
is not sufficient to generate luminosities for main-
degenerate Fermi-Dirac electron gas. Also Arnold
sequence-stars for so long.
first gave the idea of anti-matter/positrons. Immediately before this, in the same year, Pauli had introduced the 2 × 2 Pauli matrices as a basis of spin operators, thus solving the non-relativistic theory of spins. In contrast Dirac’s theory involved 4X4 matrices.
Before this, in 1926 Oskar Klein
(1894-1977) and Walter Gordon (1893-1939) had (unsuccessfully) purported to offer a relativistic theory of electrons. Klein Gordon equation was however
the
correct
relativistic
form
of
Schrodinger equation and describes the motion of a quantum scalar or psedo scalar field, a field whose quanta are spin-less particles. Pauli also postulated the existence of neutrinos by studying beta-decay in 1930. The idea of neutrinos got consolidated with the discovery of neutrons by James Chadwick (1891 -1974) in 1932. In 1934, Meghnad Saha(1893 - 1956) presented the ionization equation known by his name. This equation was crucial for the interpretation of stellar spectra. In 1935 Hideki Yukawa (1907-1981) published his theory of mesons, which explained the interaction between protons and neutrons. During 935-1938, Hans Albrecht Bethe (1906-
The development of Quantum Electrodynamics
geometrical
(QED) was completed by Richard Feynman
symmetry group. This Yang-Mills theory laid the
(1918- 1988), Julian Seymour Schwinger (1918
foundation for the Quantum Chromodynamics
-1994), Freeman Dyson (1923) and Sin-Itiro
(QCD). The so-called Higgs Mechanism by which
Tomonaga (1906 -1979) in the 1940s. QED is a
elementary particles are supposed to acquire their
successful theory not because of any
mass was first proposed by Philip Warren
mathematical novelty but because it was
Anderson (1923) in 1962. Its relativistic version got
successful in giving correct values of Lamb shift, a
developed in 1964 by many including Peter Higgs
small difference in energy between two energy
(1929).
levels
and
of hydrogen atom, and
magnetic moment of the electron. The QED calculations for the Lamb Shift were carried out by Victor Frederick Weisskopf (1908 -2002). As was noted earlier, self-gravitating objects like stars during their contraction must emit radiation. After the formulation of GTR in 1916, Prahalad Chunnilal Vaidya (1918 – 2010), first gave the expression for space-time structure around a radiating and contracting star in 1951. Physical applicability of his work was straight forward and transparent unlike many other exact solutions of GTR. In
In
symmetry
1961,
Jeffrey
Shivaramakrishnan
Pancharatnam(1934–1969) discovered a type of geometric phase sometimes known for polarized beams of particles passing through crystals. Much later, this was rediscovered by Michael Berry (1941) in 1984.
the
interaction)
Goldstone
considered the possibility of
(1933)
spontaneously
broken continuous symmetry of interaction of quantum
fields
and
attendant
spontaneous
generation of bosons. Building on the pioneering work by Schwinger, Higgs and Goldstone, Sheldon Glashow (1932), Steven Weinberg (1933) and Abdus Salam (1926 -1996) independently showed how the weak nuclear force and quantum electrodynamics could be merged into a single electroweak force. And they jointly won the 1979 Nobel Prize in Physics. However as far as pure weak interaction is concerned , its theory
1956,
of
was first proposed by
George Sudarshan (1938) & Robert Marshak (1916 -1992) in a conference paper in 1957. This theory of was in terms of ``Vector minus Axial Vector’’ (V-A) Lagrangian and crucial for the theory of weak interactions. Six months later, Feynman and Murray Gell-Mann (1939) published similar idea in a journal. As claimed by Sudarshan,
In a landmark paper published in Reviews of
Gell-Mann got this idea from him. In fact Feynman
Modern Physics in 1957 (B FH paper), Margaret
admitted in 1963 that " The V-A theory that was
Burbidge (1919) , Geoffrey Burbidge (1925-2010),
extending the initial work of Bethe.
discovered by Sudarshan and Marshak, publicized by Feynman and Gell-Mann’’. However both Marshak and Sudarshan’s contributions were ignored while awarding the 1979 Nobel Prize in Physics.
In 1954, Chen Yang(1922) and Robert Mills (1927
In 1963, Sudarshan also developed the of way of
-1999) formulated the first Quantum Field Theory
writing down the state of any type of light using
for Strong Interaction by invoking SU(3) (Special
the coherent states as a basis. Afterwards, in the
Unitary Group of Rank 3, referring to some
same year, Roy J. Glabauer (1925) presented
2
William Fowler (1911-1995) and Fred Hoyle (19152001), gave the complete theory of synthesis of various elements at the core of massive stars by
almost the same theory and won the Nobel in
many leading physicists such as Dyson, Dirac and
physics in 2005, while Surdarshan was again
Feynman were critical about such attempts.
denied due recognition!
The task of physics is to explain not only
The idea that hadrons (heavy particles) like
microscopic
neutrons and protons are made of Quarks were
interactions but also all macroscopic phenomena
independently proposed by physicists Murray
too. In the world at large, physical entities like
Gell-Mann (1929) and George Zweig(1937) in
clouds, leaves, mountains, coastlines do not have
1964. The concept of asymptotic freedom, i.e.,
well defined geometrical shapes. Neither can one
the
become
endeavour to understand climate, rainfall, storm,
asymptotically weaker as energy increases and
in terms of conventional basic physics. In other
distances decrease was predicted by
words,
bonds
between
quarks
1970s by
phenomena
when
large
and
number
fundamental
of
degrees
of
David Politzer (1949), by Frank Wilczek(1951) and
freedoms are at play, there are complex systems
David Gross (1941). Gerard 't Hooft (1949) had
which require new broad physics. Even a nucleus
also independently found asymptotic freedom
with many nucleons may behave as complex
even earlier (but did not publish).
systems. Though natural philosophers have been studying such complexities from antiquity, such
QCD is a successful theory because the PositronElectron Tandem Ring Accelerator found evidences for gluons and 1979. Later, perturbative QCD also got verified up to a certain degree in Large Electron–Positron Collider at CERN.
studies got a big leap as Benoît B. Mandelbrot (1924–2010) coined the term Fractal in 1975 and gave the modern framework for studying complex systems. CONCLUDING REMARKS:
Not only classical theories, but quantum field theories too suffered from the problem of occurrences of infinities as interaction distances would tend to zero. In classical electron theory,
renormalization, an ansatz for removing such unphysical infinities, were introduced by Lorentz and Max Abraham (1875 -1922). In the context of QED, Kenneth Geddes Wilson(1936) suggested methods of renormalization in 1970s. In the context of QCD, one of the most popular renormalization ansatz is due to Hooft and Martinus J.G.Veltman (1931). Renormalization schemes would often be motivated by condensed matter theories where the discrete structure of atoms provide natural short distance scales. On the other hand, for quantum field theories, in contrast, Plank Length (~10-33 cm), should provide such spatial cut off. Indeed, all such renormalization schemes have ad-hoc aspects and
I feel that, as of now, theoretical physics may have peaked with the formulation of the
“Standard
Model” encompassing electromagnetic, weak and strong (nuclear) interactions in the 1970s. This is so even though it is far from a fully self-constant and complete theory. In fact, the evidence for a tiny yet finite neutrino mass creeping up since 2002, is in contradiction with the predictions of SM. Yet, I think that, as of now, SM was the best bet, because (i) It does not invoke fictitious extra spatial dimensions, (ii) It does not require ad-hoc and unverified additional baggage like ``Super Symmetry’’ and most importantly. And most importantly many of the important predictions of the SM have been verified: e.g., , (i) the neutral weak currents caused by Z boson exchange
in
1973, (ii) Bottom quark discovered in 1977 (iii) W and Z bosons discovered in 1981, (iv) Top quark discovered
in
1995,
and
(v)
Tau
neutrino
Why c is considered the ultimate speed limit? Everyone is now talking about the recent results from CERN, regarding the FTL speeds recorded (after taking all possible errors into consideration) for neutrinos, one of the fundamental particles of Standard Model. Neutrinos have always been a source of trouble for physicists! The Standard Model was designed on the basis that neutrinos have no mass, and up till the 90's this assumption was very much acceptable. Requiring massless neutrinos was also a motivation from cosmology: if the neutrinos exceed a certain, small threshold for their mass (around 50 eV, that is around 9 x 10-29g), then given the sheer number of neutrinos in the Universe, it would collapse on itself rather than expand as is observed experimentally. But this problem can still be solved if the all the three neutrinos (electron-, muon- and tau-) have a combined mass of less than 0.3 eV, and one experiment in 2010 [1] did find experimental verification for that (around 0.28 eV). The current issue, that has spread like wildfire in scientific media, is more serious than the mass-problem, if it turns out to be true. Even though the speed of light being an upper limit in the universe is accepted as a postulate for relativity, there is also a logic behind this assumption. To understand this logic, we need to consider the
very simple theory of electromagnetic fields. From the Maxwell's equations in vacuum (where only the maximum speed can be possible reached):
We see from the last equation that time variations in electric field E lead to generation of magnetic field B and vice-versa from the third equation. This implies, that once started, electromagnetic fields are a self-propagating phenomenon (in vacuum, at least): it will continue to power itself in vacuum, as long as there are no obstacles in the way which dissipate the energy in the fields. It is this selfpropagating nature that makes the speed of light, c the ultimate speed in the universe. Equivalently, the constancy of speed of light (in any inertial frame) can be proved by the assumption that photon is mass-less. To get a "feel" of how c is the upper limit, consider a though experiment. Say you have a spaceship that has all the necessary machinery to accelerate instantaneously to any desired speed. Note that your spaceship is not a selfpropagating system like light, as you need to give constant
energy to the ship to make it move. This need arises, of course because in order to create an acceleration on a massive body, you need a certain finite force always (from Newton's second law). Now let there be a source of light next to you at the "starting point", from where you are about to race with the light beam. We now consider the situation just after the race has started. In order to be faster than the light beam, you need to move at a rate greater than light. That is, you need to cover more distance in a given instant of time than the light. Then say that at a time instant t0 you accelerate your ship to move faster than the rate of change of the electric field of the light just next to you. But while you powered your engine, transmitting energy through all the levers and hydraulics (electronics, mechanics, whatever the mode), remember you did all this through massive objects. Each of these objects were in turn in an initial inertia, before the "order" to change it came from you. Due to inertia alone, there will be a little delay in the system always to come to the required rate. But check what has happened in all this delay with the electric field: As soon as the E was generated at a point, it lead to creation of B at a corresponding point in a plane perpendicular to it. This B in
turn will transfer energy to generate the next E, and that to at the rate of c. Energy was oscillating simultaneously (due to light being mass-less, and hence having no inertia; I will come to the point of quantum effect later) in E and B, and the next point for creating E happened at the rate of c, while the spaceship had to struggle through its own internal massive parts to transfer the energy in the first place. Even if, by some magic, the rate of c is achieved in the next step (which is analogous to the creation of next E at the rate of c in the light beam), the ship will always incur a considerable delay in the first step to always keep its total
speed less than c. This way, no matter how hard you may try, the speed of your ship remains effectively less than c. Similar mechanism is applicable for any massive body in this universe; due to the existence of mass, inertia will always prevent a change in state (even though if it is a change in speed from v1 to v2) and this delay will always keep the speed less than the speed for a mass-less particle, that is, c. The point to understand is that relativity does not just give a special treatment to light. What it says is that only massless particles can travel at the fastest rate possible in this universe. The number for that rate (whether 3 x 105 km/s or
186,000 m/s) is determined by experiments and convention used for measurements. Now for the consideration of the quantum effect. The important point here is that the "mass" we give light, when it acts as quanta of energy (photons) is when it interacts with some form of matter. In vacuum, such effects are not there (even the quantum fluctuations are not that prominent because the time of existence of these fluctuations to actually make any significant change is extremely small, surpassing the Planck time easily), and the classical descriptions works perfectly.
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Phizy And Picky Electron Spin Intro: Phizy and Picky are two brothers, Phizy is the elder one. He is some sort of a geek on the other hand Picky the younger one is a newcomer to the world of physics here is a conversation going on between them.
"Bang" Phizy slammed the door behind while entering to his homemade lab while Picky was sitting on the table spinning the basketball on his fingers. Picky: Hey bro look its getting much better Phizy: Hmm, so calculate its angular momentum. Picky: Hey bro that’s too Bohring ;), don’t you have anything to talk? Phizy: Well Okay lets talk about something related to spin and angular momentum which seems more interesting. Have you ever heard about electrons? Picky: Ya, those little freaky creatures which are always busy getting transferred from one atom to another or always jumping up and down from one to another state, I wonder when they sleep? Phizy: Yup, you seem almost there. Did you know that they posses angular momentum? Picky: Ya brother that comes from there orbital rotation around atoms; those freaky travelers. Phizy: Well its orbital angular momentum; In addition to this they have got additional spin angular momentum.
Picky: Oh! I see, so they must be spinning around their own axis. They are busier than I have ever imagined. Phizy: Here comes the interesting part, they don’t spin. Picky: Hey are you joking? if they are not spinning then from where that spin comes from?? Phizy: No I’m serious actually it's their intrinsic property. It’s like that they have got an extra degree of freedom. The idea of the electron spin was given by Goudsmit and Uhlenback. They were studying spectral lines and observed under high resolving spectrometer that many spectral lines consist of two or more spectral lines very close to each, it cannot be explained solely on the basis of the orbital angular momentum and associated dipole moment so they coined up the term spin and successfully explained the above phenomenon, the more satisfactory explanation comes from Dirac equation which you will study later. Picky: Wait for a moment! You said they posses spin momentum but they don’t spin. Then why the term spin?? Phizy: Actually this property was so analogous to the spin motion so people believed that electron was actually spinning but later it was found that that was not the case. The word "spin" is still used well instead you can say intrinsic angular momentum but spin is lot more convenient. Picky: After all this my head has started spinning. I am doubtful at any time my eye balls could go off on a tangent.
Phizy: You need not worry; they have optical nerves to keep them in place.
thought.
Picky: Good joke! Well that seems interesting tell me more about those mighty little travelers and their so called "spin" property.
But I have a question.
Phizy: As you wish! The spin property enables electrons in two states either spin up or spin down for analogy. You can think some of them spinning in clockwise direction and rest in anticlockwise but remember its just analogy. Hence electrons exist in two different states. Picky: So you mean to say that all electrons are not same, instead they can be divided into two groups on the basis of there spin?? Phizy: Yes, you are right instead of having same mass same charge these electrons can be classified into two different groups on spin basis, remember Pauli’s exclusion principle Picky: Yup! I knew that principle which says: No two electrons can have same set of all four quantum numbers; they must at least have different spin quantum number.
Picky: I am supposed to know that, now everything seems fitting altogether.
Phizy: Go on! Picky: Can we separate them? The spin up electrons isolated from the spin down? Phizy: Yes, it’s possible and has been done before. Picky: How?? Phizy: Well you see electrons are charged particles and posses spin momentum as a result there is associated spin magnetic moment hence electrons act as tiny magnets. Since there are two directions of spin, so are for magnetic moment. As a result electrons interact in different manner with a magnetic field hence two different electron can be separated. Sternn Gerlach did this before and we will talk about that next time I have to do some work that was the reason I came here. For numerical data and more information you can search at wiki for this topic. Picky: Okay! It’s enough for today. Till then these freaky travelers are free to roam here and there. He he! :P
Phizy: That's right and spin quantum number can have two different values which is same as two state of electron. You seem to know more than I have
-Navi Rana
GET INSPIRED Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less. -Marie Curie
The Elastic stretch This article is dedicated string that is coiled to to the elasticity of rubber its full length takes and the phenomenon lesser energy than behind it. Imagine pulling a string which stretching a rubber string is uncoiled to its full and a normal string. You length. know the difference. It We can explain the pains you to stretch both elasticity of rubber of them but you can materials if we can stretch the rubber string derive an equation so much (maybe up to equivalent of the twice its length) but the Hooke's law for normal string just doesn't springs. But first let’s seem to cooperate with note what are the you to extend itself. actual physical Rubber Structure down to the Microscopic Level What's the reason? This, processes that are my friend is elasticity. It is the happening when we stretch a Lengthening of rubber phenomenon that helps the rubber: strings rubber string to "deform 1) Increase in elastic potential So what do we do when we energy due reversibly". It can also be called to changed pull the rubber string apart, we configuration. the theory that tells us the The kinetic simply draw the chemical energy we apply is what gets amount of force needed to agents away from each other stored as potential energy. deform/extend a certain and since they are the ones 2) Increase in tension till the substance by a given amount. The picture shows us how a responsible for the network so force exceeds the tension and rubber surface should look like on the polymers slowly uncoil and the rubber breaks. Prior to that a microscopic scale. It is actually expand. That is how rubbers equivalent of Hooke's law made up of coiled polymers. expand so much because of the describes its nature. More than one polymer are uncoiling action of intensely 3) On releasing, the restoring present which have been cross coiled polymers. Our force force acts. It is directly linked at points by chemical simply draws the chemical proportional to the force which agents which act as essential agents or the black circled dots binders and they are responsible apart and so they pull the for the network formed by the also apart polymers. It is the cross links that polymers define the structure and with them. is the properties of a rubber string. The That trick black circled dots in the diagram essential are actually the chemical binding behind elasticity because pulling a agents.
stretched the string and acts in a direction opposite to the displacement of string. 4) An active example of Newton’s 3rd law, the restoring force is equal to the deforming force. 5) The polymers are initially coiled in the rubber surface, On extending the string the polymers uncoil. 6) Loss of entropy, the entropy is dependent on the temperature of the system 7) On contraction of the rubber, transverse vibrations occur on the surface and they may produce an audible sound if their frequency is good enough 8) In the stretched state it is in the state of false vacuum due to less entropy. Why the string pulls back or reforms? Until now I have been explaining more or less as to why a rubber string can be lengthened so much. But now its time to speak about the other part of the phenomenon. The rigorous reformation due to the instantaneous contraction. For this let us pause for a moment. If I had a string coiled up on my table and I pull it to its full length it doesn't cost me any energy at all, it’s all so easy. Taking this analogy we should assume that a rubber string too should lengthen easily without any resistance too, but that doesn't happen. We do have to exert good amount of force. Sometimes too much which goes on increasing with expansion. Now plays the role of ENTROPY.
What is Entropy? It is the amount of disorder in a system. And there's a very fundamental law related to it that entropy always goes on increasing meaning thereby that the disorder in whole universe is increasing. We buy an icecream cone which is ordered and we eat it up and so now it’s disordered. We buy a brand new car which is ordered but we bump against something delivering injuries to our car and so now it’s disordered. And if you think properly there are so many ways to break things but only few or maybe only one way to join it up. Taking this into account we might say that systems are always happy at the state of highest entropy. The coiled polymer is in absolute disorder but a long fine polymer string is ordered. So entropy decreases on stretching a rubber string and thus the systems turn unhappy as entropy is supposed to increase, not decrease. This is what makes the difference. The system again tries to return to its disorderly state to maintain itself with the entropy law and exerts a restoring force which is directly proportional to the force applied to lengthen the string and it acts in a direction opposite to the direction of displacement of the spring. When the network is stretched, entropic forces come into play which favors retraction, returning the network to its original unstretched
/equilibrium state. Loss of entropy upon stretching means that there is a retractile force for recovery when external stress removed. This is why a rubber band returns to its original shape. Hooke's law equivalent equation for rubber strings As our starting point, let us consider a spring attached to a wall and pulling to it. How much force do I need to do this? This is given by the Hooke's law. Let F be the force
and x be the extension of the spring from its rest length. Then F=-kx is the statement of the Hooke's law and is governed by a single constant, the spring constant for the spring I am using. We started like this because we can get a reasonable theory for the elasticity of a solid if you considered it to be made up of atoms connected by springs whose spring constant is defined by the electromagnetic interactions between the atoms. The energy scale for these is electron volts which makes these strings quite stiff.
Comparing a rubber string with a spring, we observe that as we pay an energy cost to stretch a spring and so do we pay an entropy cost to stretch a rubber band. If we calculate this cost, we get to derive the Hooke's law equivalent for strings. Then we find that if we need to stretch a string by x, the
force we need is F= (CT/L)x where T is the temperature of the system, C is a constant and L is the length of the polymer. So the polymer behaves like a spring with a spring constant determined by the temperature of the system. And the systems are so similar only because strings extend by loss in entropy rather than gain in energy like springs. That is why they are called "ENTROPIC SPRINGS". So polymers are actually very loose springs. So polymers form entropic springs whose stiffness increase with temperature. That is why rubber turns brittle and breaks when we stretch it on hot
summer days. Conclusion So as we saw rubbers are simply springs in which entropy takes a major role. So the simple rubber bands in our house are real depositories of some tough physics. And this is yet another confirmation of the fact that physics surrounds us everywhere in everything we do. And this is why we, physics lovers at physics de pristine strive to entertain you readers with this tremendous involvement of physics in everyday life and thus stress on its significance and popularize it as well.
Food For Brain!! •
The lungs contain over 300,000 million capillaries (tiny blood vessels). If they were laid end to end, they would stretch 2400km (1500 miles).
•
A mans testicles manufacture 10 million new sperm cells each day – enough that he could repopulate the entire planet in only 6 months!
•
Human bone is as strong as granite in supporting weight. A block of bone the size of a matchbox can support 9 tonnes – that is four times as much as concrete can support.
•
The average person in the West eats 50 tonnes of food and drinks 50,000 liters (11,000 gallons) of liquid during his life.
•
The eyes receive approximately 90 percent of all our information, making us basically visual creatures.
THE SYMPLECTIC EGG -Maurice de Gosson Take an egg --preferably a hard boiled one-and cut it in half along its middle using a very sharp knife. The surface of section will be a circle. Next, take a new egg of same size, and cut it this time along a line joining the egg's tops. The surface of section will now be roughly an ellipse, whose area is much larger than that of the circle we got previously. So far, so good. But if you now take a pair of symplectic eggs, and do the same thing, then both sections will have exactly same area. Even "worse", no matter along which plane passing through the center of the egg you cut, you will always get sections having the same area! This is admittedly a very strange property, which you probably never have encountered (at least in a visible way) in everyday life. But what is a symplectic egg? The eggs we have been using are metaphors for ellipsoids; an ellipsoid is a spherical ball that has been deformed by a linear transformation of space, i.e. a transformation preserving the alignment of three, or more, points. In mathematics such transformations are represented by matrices, which are square arrays of numbers. Thus the datum of an ellipsoid is the same thing as the datum of a ball and of a matrix. What we call, somewhat jokingly, a symplectic egg is an ellipsoid corresponding to the case where the matrix is symplectic. The reason for which you haven't probably never seen a symplectic egg, is that the number of rows and columns of a symplectic matrix must always be even. But that property is not sufficient for an egg to be symplectic. We need something more,
which is a property of the entries of the matrix. In the case of smallest dimension, which is two, this condition is quite easy to formulate: if the first row of the matrix is (a,b) and the second (c,d) it is only required that ad-bc=1. In higher dimensions, 4, 6, 8, etc. there are many more conditions: for instance 6 if the dimension is 4, 21 if it is 6, and d(2d+1) if the dimension is 2d. and I will not write these conditions here, suffice it to say that they exist, that is, symplectic eggs are real (this somewhat abrupt statement allows me (us) to get rid of embarrassing technicalities!). So far, so good. But where do symplectic eggs come from, and what are they good for? I am going to explain in a moment where these very special eggs come from, but let me first tell you where symplectic matrices come from. They initially come from the study of motion of matter, which is really rich in mathematical concepts, some of these going back to the work of Galileo Galilei, Johannes Kepler, and many other (the "Giants" on the shoulder's of which Isaac Newton stood). But the notion of symplectic matrix, or more generally that of symplectic transformation, did really have a long time to wait until it appeared explicitly and was recognized as a useful concept. It was implicit in the work of Hamilton and Lagrange on classical and celestial mechanics, until the word "symplectic" was finally coined by the mathematician Hermann Weyl in his book The Classical Groups, edited in 1939, just before World War II. But still then it was a rather baffling
oddity which presumably existed for some purpose --but which? It was only later discovered that the purpose of symplectic transformations is dynamics, that is the study of motion. Let me explain: if we have a physical system consisting of "particles" (sand corns, planets, spacecraft, or electrons) it is economical from both a notational and computational point of view to describe their motion (that is, their instantaneous location and velocity) by specifying a vector, which is a matrix having only one column, and whose entries are first the position coordinates of the particles, and then, in corresponding order, their momenta (the momentum of a particle is just its velocity multiplied by its mass m). The set of all these vectors form what is commonly called the phase space of our system of particles. It turns out that if we know a certain function, called the Hamiltonian (or energy function), we can predict the motion of our particles; this is done by solving (exactly, or numerically) a certain system of equations, called Hamilton's equations of motion (mathematically these are just a fancy way to write Newton's second law F=ma). That is, knowing exactly the positions and the momenta at some initial time, we are able to know what these are going to be at any future time (we can actually also calculate what they were in the past). The surprising, and for us very welcome, fact is that the transformation which takes the initial configuration to the future configuration is always a symplectic transformation! These act on the phase vectors, and once this action is known, we can determine the future of the whole system of particles, and this at any moment (mathematicians would say we are in presence of a "phase space flow"). The relation between symplectic transformations and symplectic matrices is that we can
associate a symplectic matrix to every symplectic transformation. In the simplest cases, for instance when no external forces act on the particles, these matrices are themselves the symplectic transformations. The symplectic egg is a special case a deep mathematical theorem discovered in 1985 by the mathematician Gromov, who got the Abel Prize in 2010 for his discovery (the Abel Prize is the "true" substitute for the Nobel Prize in mathematics); that theorem is nicknamed the "principle of the symplectic camel", and it says that it impossible to squeeze a symplectic egg through a wall of "conjugate coordinates" if its radius is larger than that of the hole. That one can do that with an ordinary egg is easy to demonstrate in your kitchen: put the egg (unboiled this time) into a cup of vinegar (Coca Cola will also do!) during 24 hours. Then you will be able to squeeze that egg through the neck of a bottle without much effort! The marvelous thing with the symplectic egg is that it contains quantum mechanics in a nutshell... er... an eggshell! Choose for radius the square root of Planck's constant h divided by 2pi (h is a tiny physical constant). Then each surface of section will have radius of h/2. It is possible and in fact quite easy if you know the rules of the game, to show that this is equivalent to the uncertainty principle of quantum mechanics. The thing to remember here is that a classical property (i.e. a property involving usual motions, as that of planets for instance), which is here symbolized by the symplectic egg, contains as an imprint quantum mechanics. The analogy between "classical" and "quantum" can actually be pushed much further, as I have shown with basil Hiley. But this is another story which I will tell you another time.
Why does partition in time confuse minds? Our universe can be regarded as a collection of events , which are all entwined with other through space and time,an entity which is called as "continuum. In order to specify time and space intervals between two events,it is necessary to allocate values to four different variables (A,B,C,D). Each observer despite having the ability to distinguish properly between space and time,is not synchronized with the others. What one measures as time is interpreted by the other partly in space and partly in time. This diversion from the true values on an individual scale or rather the distinction is subjective. The observers being influenced by the circumstances and their corresponding evaluation. However one can conclude that in an objective plane of reality these discrepancies are non -existent. The logical assumption would be that we live in a four dimensional world,divided arbitrarily by each observer into three dimensions of space and one of time. This is a feature of our world called "space-time".Owing to the fact that people on Earth never move relatively to each other with really high velocities,the time and distant axes of any one person agree fairly well with those of any other. Life would be a perplexing and embarrassing matter if this balance
ceased to exist..Thus the distinction between space and time observed by a hypothetical inhabitant of an alpha particle with a velocity moving close to light speeds is considerably different from that of a physicist observing him that any modicum of social contact would be rendered practically unthinkable. Every observer maps out the universe with his own space and time axes. Suppose an observer K were to classify a large number of events which occurred at the same moment. This collection of events forms a timesection or time -cleavage by K of the universe. Thus the time sections of different observers are not the same. Each sees the universe through his own eyes .The universe as a whole is timeless and space-less. What each of us perceive is merely our own self defined time-sections. One could further venture out into assuming that our Past ,Present and Future are present in our Four Dimensional universe as one entity partitioned only by the axes of Space and Time. -Ps Prathin
The Unknown Universe One of the key questions that needs to be
properties of non-baryonic matter with itself.
answered by astrophysicists is what is really
The data from WMAP shows that the
out there? Which immediately leads to
universe is flat, which implies that the mean
another question, what is it all made up of?
energy density in the universe is equal to the
Without this understanding it is impossible
critical density (within a 1% margin of error)
to come to any firm conclusions about how
which is equivalent to a mass density of 9.9 x
the universe evolved. Everything which we
10-30g/cm3, which is equivalent to only 5.9
encounter in our daily lives is made up of
protons per cubic meter. Of this total density,
three
we now know, the composition stands as
fundamental
neutrons
and
particles:
electrons
protons,
(protons
and
follows:
neutrons are together referred as baryons).
4.6% Atoms. The normal matter or the
Until about thirty years ago, astronomers
baryonic matter contributes only to 5% of the
thought that the universe was composed
total energy density. Which means that all the
almost entirely of this "baryonic matter",
galaxies and the intergalactic medium which
ordinary atoms. However, in the past few
we directly observe are but a small fraction of
decades, there has been ever more evidence
what is really out there.
accumulating
is
23% Cold Dark Matter. Dark matter is likely to
something in the universe that we cannot
be composed of one or more species of sub-
see, perhaps some new form of matter.
atomic particles that interact very weakly with
that
suggests
there
ordinary matter. Particle physicists have many Using the Wilkinson Microwave Anisotropy
plausible candidates for the dark matter, and
Probe (WMAP), scientists have been able to
new particle accelerator experiments are likely
measure the fluctuations in the cosmic
to bring new insight in the coming year.
microwave
high
72% Dark Energy. The first observational hints
precision (relative density of baryonic and
of dark energy in the universe date back to
non-baryonic matter to an accuracy of better
the 1980's when astronomers were trying to
than a few percent of the overall density)
understand how clusters of galaxies were
which
formed.
has
background
helped
in
to
a
very
calculating
the
Their
attempts
distribution
of
to
explain
galaxies
the
parameters of the big bang very accurately.
observed
were
The fact that the mass of the non-baryonic
improved if dark energy was present, but the
matter and its interaction with the ordinary
evidence was highly uncertain. In the 1990's,
matter affects the details of the cosmic
observations of supernova were used to trace
microwave background fluctuation spectrum,
the expansion history of the universe (over
has helped in determining some of the
relatively recent times) and the big surprise
was that the expansion appeared to be
roughly 5% of the contents of the universe,
speeding up, rather than slowing down! There
but we, for a large part of it have no idea
was some concern that the supernova data
where does that 5% lies. I shall explain that as
were being misinterpreted, but the result has
we proceed.
held up to this day. In 2003, the first WMAP
Although baryons are believed to be
results came out indicating that the universe
a minor constituent of the mass-energy
was flat (see above) and that the dark matter
budget of our universe, they have played a
made up only ~23% of the density required to
dominant role in astronomy because they are
produce a flat universe. If 72% of the energy
the only component that interacts directly and
density in the universe is in the form of dark
frequently with light. Indeed, much of modern
energy, which has a gravitationally repulsive
astrophysics focuses on the production and
effect, it is just the right amount to explain
destruction of heavenly bodies comprised of
both the flatness of the universe and the
baryons. Out of the total baryonic matter
observed accelerated expansion. Thus dark
formed right after the big bang, cosmic
energy
baryon census estimates have shown that in
explains
many
cosmological
observations at once.
our present universe only ~6-10% of the matter has collapsed into luminous structures called galaxies, which means that this is the only fraction available for direct observation. The bulk of the baryons did not collapse and are present in circumgalactic regions and in the
unvirialized
large-scale
intergalactic
filaments (Mulchaey et al.1996; Fukugita et al.1998; Fig1. The composition of the universe (present time)
conclusively the existence of either dark energy or dark matter. Though, recent reports based
Hydrodynamic
on
the
redshift
measurement
of
supernova type Ia does seem to indicate the existence of dark energy , the proof is far from conclusive. So it turns out that we know hardly about 5% of what makes the universe. Well, not really. Yes we do know with a level of certainty that baryonic matter contributes to
&
Peebles
simulations
of
2004). structure
formation predict that this missing portion from
So far, no one has been able to prove
Fukugita
the
baryon
gravitationally
inventory
shock-heated
is
in
phase
a
with
temperatures in the range of T∼10 –10 K and 5
densities
of
7
nH∼(0.1–10)×10−5cm−3(Cen
&
Ostriker 1999; Dave et al.2001; Valageas et al. 2002). Since the temperature of these portion is in the range of 105-107 K, x-rays are by far the most suited band in the electromagnetic spectrum to probe them. Discovering this warm-hot intergalactic medium (WHIM) is one of the main science drivers for the Cosmic
Origins
Spectrograph
(COS)
on
HST
really know about is 2% of the composition of
(Shull2009)and a lot of scientific missions has
the universe. Every one, while talking about
been for the same purpose. For example
the composition of the universe explains that
Space Telescope Imaging Spectrograph (STIS)
universe is composed of roughly 5% of
aboard the Hubble Space Telescope(HST) and
baryonic matter, but what almost everyone
Far-Ultraviolet spectroscopic Explorer (FUSE)
fails to mention is the fact that we are yet to
have helped in finding a significant fraction
locate the 50% of that 5%. We know so little
(~50%) of the baryon lying outside of galaxies
about the universe! There is so much to be
in the nearby universe. The rest of the baryons
found, so much to explore, and so much
are yet to be found. Which means that we are
unknown lies there. At times it frightens me to
yet to find roughly half of the known matter
the core and strives me to understand it
of the universe, and we thought dark matter
better and drives my passion.
and dark energy are the only thing to be found.
So,
with
no
idea
about
the
-Ahmad Ryan
whereabouts of dark matter and dark energy and half of the baryonic matter, all that we
l Did You Know? p 1. There are 62,000 miles of blood vessels in the human body – laid end to end they would circle the earth 2.5 times. 2. At over 2000 kilometers long, The Great Barrier Reef is the largest living structure on Earth. 3. The risk of being struck by a falling meteorite for a human is one occurrence
every 9,300 years. 4. A thimbleful of a neutron star would weigh over 100 million tons. 5.
A typical hurricane produces the energy equivalent of 8,000 one megaton
bombs.
On Collision Course With The Andromeda Galaxy
– Robin Anderson
I want to cover up something that I've noticed people in my vicinity are struck by every time they hear this following statement. - Did you know that we are on a collision course with the Andromeda Galaxy? - How could that be possible, if the universe is expanding? Yes, is that possible? I'll tell you. The expansion of the universe, is a remarkable discovery for human kind itself. It was in 1929, Edwin Hubble discovered that the universe is
expanding, the discovery was made when he noticed that the redshift of galaxies increased linearly with distance.
distance immense. That the light is getting redshifted so much which will make it very hard to detect them, and eventually - undetectable. Because the redshift corresponds to the light having a lower energy, the more redshift, the less energy. How then can we collide with another galaxy when the universe is moving everything apart? The expansion of the universe, is said to dominate on large scales. That is, the pulling apart, is very strong relative to galaxies very far away. The Andromeda Galaxy however, is very close astronomically speaking. The force between our galaxy and the Andromeda Galaxy is stronger, than the "force" (not a force literally) pulling us apart.
Later in 1998, not that long Colliding galaxies, Arp 272 That said, the sun is not ago, it was another expanding away from us, the distance between discovery made, the expansion of the universe the atoms in molecules is not increasing, we are is accelerating. However we are not here to talk bound to it with a very strong force, and the about the implications of the accelerating atoms are bound as well to each other. The expansion. But the information can be useful to same goes for the entire galaxy, moons to have in hand. planets, planets to stars, stars to other stars and The expansion of the universe has serious the central black hole. However, distant objects implications for all living creatures that will exist are soon enough long gone. But that is a very, to glare upon the night sky in the future. The very, very long time away from now. We have no expanding universe will separate all galaxies need to worry, but the fact that this is apart soon enough if you give it enough time, happening, is for me, very fascinating! and this will make the universe look "empty". How? Remember, the expansion of the universe When the galaxies are moving apart, their dominates on large scales. The Andromeda speed relative to each other increase, and of Galaxy is, as said, close. So yes we are colliding course the distance, soon enough the speed with it even though the universe is expanding. relative to one another is so high, and the
Where NASA built the rockets “It's hard to see how big VAB (Vehicle Assembly Building) is UNTIL you look down at the bottom and you can see a man walking through the door” Credits : Trey Ratcliff www.stuckincustoms.com
We have been hearing so much about particle accelerators and particle detectors in the last few years. The best known particle accelerator possibly is the Large Hadron Collider (LHC) at the CERN in Switzerland. The particle detectors associated with it are CMS, ALICE, ATLAS etc. I am not going in details about the so called “GOD-particle”, because I believe that a person interested in my article would be well aware of that. So what I want to ask here that can we make our own particle detector? Well yes, it is indeed possible to make a “cloud chamber” at home and view elementary particles like muons and electrons from the cosmic rays incident on earth. For sure that would not be comparable to the LHC, but my friend we will also not spend those millions on it. Some things for the readers with fewer introductions to Standard model of Particle Physics:- In the standard model there are twelve elementary fermions, six quarks and six leptons. The six leptons are three neutrinos and three electron-like particles. The three electron-like leptons are the electron, the muon and the tau particle. All three have negative charge and their spin is half. Fermions are thus grouped in three generations, each generation consisting of a charged lepton and its associative neutrino. The cloud chamber is a particle detector invented by British scientist C.T.R. Wilson in the early twentieth century, for which he received the Nobel Prize in Physics in 1927. A cloud chamber consists of a sealed environment containing a super-saturated vapour of water or alcohol. The vapour condenses on the ionizing particle (alpha or beta), thus leaving a trail. The tracks can be seen with the help of a tangential light source. The bottom of the chamber is cooled. This creates a temperature difference between the top and bottom of the chamber. Now coming back to the topic, We need a transparent plastic container for the body and a metal plate for the bottom surface of the cloud chamber. The metal plate should be black to provide a suitable backdrop for the tracks. However, if you can’t get hold of a black metal plate then just paint it black or wrap it with black tape. Keep some putty or tape at hand to attach the container and plate to each other. Next, we need a piece of felt. The felt will be used to introduce the alcohol into the chamber. And then you need some dry ice to cool the chamber. The local ice cream vendor parlour can help you out with getting dry ice if you don’t know where to get it. And to keep the dry ice you need an insulating box made from wood or thermocol. Get some ethyl or isopropyl alcohol from your school’s chemistry lab. Find a torch with a strong beam to provide the lightning. And you now have all your raw materials ready. How do we put together a working cloud chamber from all these things? Stick the felt to the bottom of the plastic box. Soak it with the alcohol using a draper. Remember that the alcohol should not touch your bare skin. Also it is poisonous so do not try to drink it. Put the box upside down on the metal plate. The felt lined bottom is now on top. Seal the box to the plate using the tape. Make sure the arrangement is airtight; otherwise you won’t get proper tracks. Now take the dry ice and put it below the metal plate. This sets up the temperature gradient and you should be able to see a sort of ‘rain’ at the bottom of the chamber. Remember to handle the dry ice wearing gloves otherwise you will get a burn from the extremely cold ice. Also, the room should be ventilated because when the dry ice melts carbon dioxide will be formed. Once you have completed all these steps turn off the lights in the room. Point the flashlight at the chamber from the side and wait for the tracks to appear.
- Sushant Rawat
India about to get its first and the worlds most advanced Synchrotron! Another precious feather is about to get attached to the crown of Nuclear Physics Research and Development in India. India will be getting a new Synchrotron which is the 5th Synchrotron in the world and also the most advanced one according to scientists. At present there are only 4 Synchrotrons which are at Japan, United States of America, France and Germany! The Saha Institute of Nuclear Physics (SINP) based in Kolkata has been given the charge to develop the Synchrotron. Even the scientists at the Indian Institute of Science, Bangalore were keen to build the Synchrotron but ultimately SINP got the green signal from the Government of India.
- Mayukh Saha
Synchrotron is far more modified and advanced. While a cyclotron follows a spiral path, a Synchrotron follows a closed cyclic path. With variations in the magnetic field at different places with relative time interval, the particle beam is made to follow a total cyclic path.
How is a Synchrotron useful to citizens? Well, Synchrotron can surely be a great help in research and innovation. A Synchrotron can help in the following ways:
So what really is a Synchrotron? In plain words, a synchrotron is a type of cyclic particle accelerator. That means electrons and other fundamental nuclear particles are made to move in a closed path under magnetic field which bends the particles into a cyclic path, to form a particle beam of increasing kinetic motion which in turn give rise to enormous amount of energy and is useful in different fields of scientific research like High Energy Physics, Particle Physics, Biotechnology, Biochemistry, etc. The very first electron synchrotron was constructed by Edwin McMillan in 1945.
• Treatment of Cancer. • Finding the compositions of minerals and the different substances that compose it. • Finding the fundamental source of particles that cause pollution, mainly air and water pollution. • In discovering new ways of producing modified seeds that are more resistant to harsh climatic conditions. • Medical Imaging. • Geological Material Analysis. • Burning computer chip designs into metal wafers. • Fluorescence studies. • Semiconductor material analysis and structural studies.
How does a Synchrotron work? A Synchrotron basically works in the principles of a Cyclotron, where there is a constant magnetic field to guide the particle beam and bend it, along with a constant frequency electric field to give the particle kinetic energy. But a
Moreover, a Synchrotron generates Synchrotron Radiation, that is, emission of light that can be as intense as about what an x-ray source generates. In fact, it can be about 12times stronger in magnitude compared to the x-ray source. Not only that,
the light also spans over a large range from far infra-red to hard x-rays. So How is the Synchrotron Radiation Produced? When the moving charged particle undergoes an acceleration, it emits electromagnetic radiation. Similarly the electrons involved in Synchrotron ring, revolve and undergoes acceleration at the bending magnets of the accelerator and thereby light is produced. If the electron is slow, the radiation emitted is isotropic. Actually, this is a relativistic effect. Suppose you are sitting on the high speed electron, then, you will be able to see the light emitting isotropically. While, for the observer in
the laboratory, the light is well collimated! Properties of Synchrotron Radiation: • • • • •
Broad Spectrum from microwaves to X-rays. High Flux. High Brilliance (spatial coherence) High Stability: sub-micron source stability. Polarization: both linear and circular. Synchrotron is a useful instrument in present day world of scientific research development and technology. And India surely will look forward to benefit a lot in research from the new Synchrotron it will have.
- Mayukh Saha
Did you know? •
Athazagoraphobia is the fear of being forgotten or ignored.
•
Researchers at Essex University have found that teens who have never smoked, nor drank alcohol are 4 to 6 times more likely to be happier.
•
The smell of freshly cut grass is actually the scent released by plants in distress.
•
A strawberry is not an actual berry, but a banana is.
•
If a person’s pupils are dilated when they’re talking to you, they are more likely to be interested in you.