The most famous American astronomer and astrophysicist Carl Sagan explains the D...
"Books permit us to voyage through time, to tap the wisdom of our ancestors. The...
World famous astronomer and astrophysicist, the great Carl Sagan, explains the 4...
and presenting the award-winning 1980 television series "Cosmos: A Personal Voya...
Carl Sagan discusses the lives of stars. "All this churning power is driven by t...
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Views: (3749) Date: (20-01-09) Time: (00:10:55) |
Description:
Carl Sagan discusses the lives of stars. "All this churning power is driven by the Sun's interior, which is converting four-hundred million tons of hydrogen into helium every second." This is from Carl Sagan's Cosmos episode 9, "The Lives of Stars."
Carl Edward Sagan (November 9, 1934 – December 20, 1996) was an American astronomer, astrochemist, author, and highly successful popularizer of astronomy, astrophysics and other natural sciences. He pioneered exobiology and promoted the Search for Extra-Terrestrial Intelligence (SETI).
He is world-famous for writing popular science books and for co-writing and presenting the award-winning 1980 television series Cosmos: A Personal Voyage, which has been seen by more than 600 million people in over 60 countries, making it the most widely watched PBS program in history. A book to accompany the program was also published. He also wrote the novel Contact, the basis for the 1997 Robert Zemeckis film of the same name starring Jodie Foster. During his lifetime, Sagan published more than 600 scientific papers and popular articles and was author, co-author, or editor of more than 20 books. In his works, he frequently advocated skeptical inquiry, secular humanism, and the scientific method.
Carl Sagan was born in Brooklyn, New York to a Russian Jewish family. His father, Sam Sagan, was a Russian immigrant garment worker; his mother, Rachel Molly Gruber, was a housewife. Carl was named in honor of Rachel's biological mother, Chaiya Clara, "the mother she never knew", in Sagan's words. Sagan graduated from Rahway High School in Rahway, New Jersey in 1951.[4] He attended the University of Chicago, where he participated in the Ryerson Astronomical Society, received an A.B. with general and special honors (1954), a S.B. (1955) and a S.M. (1956) in physics, before earning a Ph.D. degree (1960) in astronomy and astrophysics. During his time as an undergraduate, Sagan spent some time working in the laboratory of the geneticist H. J. Muller. From 1960 to 1962 he was a Miller Fellow at the University of California, Berkeley. From 1962 to 1968, he worked at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts.
Sagan lectured annually at Harvard University until 1968, when he moved to Cornell University. He became a full Professor at Cornell in 1971 and directed the Laboratory for Planetary Studies there. From 1972 to 1981 he was Associate Director of the Center for Radio Physics and Space Research at Cornell.
Sagan was a leader in the U.S. space program since its inception. From the 1950s onward, he worked as an adviser to NASA. One of his many duties during his tenure at the space agency included briefing the Apollo astronauts before their flights to the Moon. Sagan contributed to most of the robotic spacecraft missions that explored the solar system, arranging experiments on many of the expeditions. He conceived the idea of adding an unalterable and universal message on spacecraft destined to leave the solar system that could be understood by any extraterrestrial intelligence that might find it. Sagan assembled the first physical message that was sent into space: a gold-anodized plaque, attached to the space probe Pioneer 10, launched in 1972. Pioneer 11, also carrying the plaque, was launched the following year. He continued to refine his designs throughout his lifetime; the most elaborate message he helped to develop and assemble was the Voyager Golden Record that was sent out with the Voyager space probes in 1977.
At Cornell, Sagan taught a course on critical thinking until his death in 1996 from a rare bone marrow disease. The course had only a limited number of seats. Although hundreds of students applied each year, only about 20 were chosen to attend each semester. The course was discontinued immediately after Sagan's death, but was later resumed by Professor Yervant Terzian in 2000.
Carl Sagan's contributions were central to the discovery of the high surface temperatures of the planet Venus. In the early 1960s no one knew for certain the basic conditions of that planet's surface and Sagan listed the possibilities in a report later depicted for popularization in a Time-Life book, Planets. His own view was that Venus was dry and very hot as opposed to the balmy paradise others had imagined. He had investigated radio emissions from Venus and concluded that there was a surface temperature of 500 °C (932 °F). As a visiting scientist to NASA's Jet Propulsion Laboratory, he contributed to the first Mariner missions to Venus, working on the design and management of the project. Mariner 2 confirmed his conclusions on the surface conditions of Venus in 1962.
Sagan was among the first to hypothesize that Saturn's moon Titan might possess oceans of liquid compounds on its surface and that Jupiter's moon Europa might possess subsurface oceans of water. This made Europa potentially habitable for life. Europa's subsurface ocean of water was later indirectly confirmed by the spacecraft Galileo. Sagan also helped solve the mystery of the reddish haze seen on Titan, revealing that it is composed of complex organic molecules constantly raining down onto the moon's surface.
He further contributed insights regarding the atmospheres of Venus and Jupiter as well as seasonal changes on Mars. Sagan established that the atmosphere of Venus is extremely hot and dense with pressures increasing steadily all the way down to the surface. He also perceived global warming as a growing, man-made danger and likened it to the natural development of Venus into a hot, life-hostile planet through a kind of runaway greenhouse effect. Sagan and his Cornell colleague Edwin Ernest Salpeter speculated about life in Jupiter's clouds, given the planet's dense atmospheric composition rich in organic molecules. He studied the observed color variations on Mars’ surface and concluded that they were not seasonal or vegetational changes as most believed but shifts in surface dust caused by windstorms.
Sagan is best known, however, for his research on the possibilities of extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation.
He is also the 1994 recipient of the Public Welfare Medal, the highest award of the National Academy of Sciences for "distinguished contributions in the application of science to the public welfare."
SOURCE: WIKIPEDIA (http://en.wikipedia.org/wiki/Carl_Sagan)
Quantum and Entropy, Vacuum, Gravity, Star formation . . .etc.
=======...
1.
Henry Poincare named the conception of "entropy "
as a " surprising abstract ".
2.
Lev Landau (Dau) wrote:
" A question about the physical basis of the
entropy monotonous increasing law remains open ".
3.
One physicist said :" The entropy is only a shadow of energy.
4.
The mathematician John von Neumann said to
"the father of information theory" Claude Shannon:
" Name it "entropy" then in discussions
you will receive solid advantage, because
nobody knows, what "entropy" basically is ".
==========..
1.
Between 1850 - 1865 Rudolf Clausius published a paper
in which he called " The energy conservation law" as
" The first law of thermodynamics". But in our nature the
heat always flows from the higher temperature to the
lower one and never back. In our everyday life we don't see
the heat itself rises from cold to hot. So, it seemed that
in thermodynamics " The energy conservation law"
wasn’t kept, this law was broken. But Clausius had another
opinion. He thought: I know people believe that this process is
irreversible, but I am sure that " The energy conservation law"
is universal law and it must be correct also for thermodynamic
process. So, how can I save this law ?
Probably, in the thermodynamic process there is something
that we don't know. Maybe, there is some degradation
of the total energy in the system which never disappears .
Perhaps, there is some non-useful heat, some unseen process ,
some unknown dark energy , some another form of potential
energy/heat itself which can transform heat from the cold
body to the warm one. I will call this conception as " entropy"
and it will mean that changes of entropy (dS) can be calculated
for reversible process and may be defined as the ratio of the
quantity of energy taken up (dQ) to the thermodynamic
temperature (T), i.e. dS= dQ /T.
And because I don't know how this process goes I won't call
it as a law but as " The second principle of thermodynamics "
which says that " the entropy of an isolated system always
increases ". Another version: " No process is possible
in which the only result is the transfer of heat from a hotter
to a colder body. It is possible some reversible process which
is unknown now ."
2.
Between 1870 - 1880 Ludwig Boltzmann said:
" Clausius is right. But I can add more to his entropy conception.
First.
According to Classic physics when an isolated thermodynamic
system comes to a thermal equilibrium all particles stop their
moving. From one hand it is correct. But the system cannot be
at thermal equilibrium (in the state of thermo death) all the time.
The situation in the system must change.
Therefore I say that at the thermal equilibrium the entropy
(some unknown dark/potential energy ) of the system will
reach maximum and as a result , the thermal equilibrium
of the system will change.
Second.
I don't know how exactly the thermal equilibrium of the system
changes. But I can give probabilistic / statistical interpretation
of this changing process. I can write " The second principle of
thermodynamics" by a formula: S= k log W and this formula
says:" the entropy ( heat) of the system is the collective result of
mechanical motion and friction of all the particles (k)."
I will call it as " The second law of Thermodynamics."
3
In 1900 Max Planck said:
Clausius and Boltzmann are both right.
But all my life I worked almost exclusively on problems
related to thermodynamics. And I am sure that the " The second
law of Thermodynamics" , concerning entropy, is deeper and it
says more than is generally accepted. I am sure the Boltzmann's
probabilistic /statistical version of "The second law of
Thermodynamics " is not completed, is not final.
Please, look at the graph of the radiation curves of the " black body".
They are very similar to those curves which are calculated
by Maxwell for the velocity (i.e. energy) distribution of gas
molecules in a closed container. Could this black body radiation
problem be studied in the same way as Maxwell's ideal gas....
...electromagnetic waves ? This problem of connection between
radiation of black body and Maxwell's Electrodynamics theory
doesn't give me peace. Maxwell's theory can tell everything
about the emission, absorption and propagation of the radiation,
but nothing about the energy distribution at thermal
equilibrium. What to do? How to be ?
After trying every possible approach using traditional
classical applications of the laws of thermodynamics
I was desperated. And I was forced to consider that the
relation between entropy, Boltzmann's probability version
and Maxwell's theory is possible to solve by suggestion ,
that energy is radiated and absorbed with discrete
individual quanta particle ( E= hf). So, now I must write
" The second law of Thermodynamics " by formula:
hf = k log W.
But if I look to the Clausius inequality I see that entropy
is energy divided per temperature.
So the formula hf = klogW is hf = kT logW I think.
I was so surprised and skeptical of such interpretation
the entropy that I spent years trying to explain this result
in another , less revolutionary way. It was difficult for me
to accept this formula and to understand it essence .
It was hard for me to believe in my own discovery.
==================..
My conclusion.
How to understand this formula?
Which process does formula (hf = kT logW ) describe ?
1.
In 1877 Boltzmann suggested that the energy/mass state
of a physical system (of ideal gas ) could be discreted.
This idea was written with formula: R/N=k. It means:
there are particles with energy/mass state (k) in physical
system of ideal gas . They don’t move, they are in the
state of rest.
2.
In 1900 Planck followed Boltzmann's method of dividing.
Planck suggested that energy was radiated and absorbed
with discrete "energy elements" - " quantum of energy"-
- " Planck's action constant"- (h) . This fact means:
electron produces heat, setting in mechanical motion and
friction all particles. This fact is described with Planck's
formula: hf = kTlogW.
3.
In which reference frame does this process take place?
In thermodynamical reference frame of ideal gas and
black body (M. Laue called this model as Kirchhoff’s vacuum).
Now it is considered that these models are abstract ones which
do not exist in nature. On my opinion these models explain
the situation in the real Vacuum (T=0K) very well.
4.
For my opinion the formula (hf = kT logW ) says:
a)
The reason of " entropy" , the source of thermal equilibrium's
fluctuation , the source of Vacuum fluctuation is an action of
the particle /electron, which has energy: E = hf.
b)
The process of Vacuum fluctuation depends on collective
motions of all particles (k) and will be successful if enough
statistical quantity of Boltzmann's particles ( kT logW)
surround the electron.
c)
Which process does the formula (hf = kT logW ) say about ?
This formula describes the possibility of realization of
macro state from micro state. This formula explains
the beginning conditions of gravitation,
the beginning conditions of star formation.
1.
hf = kT logW.
hf > kT logW.
hf < kT.
2.
hv --> He II --> He I -->
( P. Kapitza , L. Landau , E.L. Andronikashvili theories).
(Superconductivity, superfluidity.)
3.
Plasma reaction... -->
4.
Thermonuclear reactions ...-->......etc.
d)
Thanks to Entropy the homogeneous Vacuum is broken.
Thanks to Entropy the micro process changes into
macro process.
Thanks to Entropy the stars formation takes place.
Thanks to Entropy " the ultraviolet catastrophe" is absent.
Thanks to Entropy our Milky Way doesn't change into radiation.
Thanks to Entropy the process of creating elements takes place.
Thanks to Entropy the process of evolution is going.
e)
One physicist said :" The entropy is only a shadow of energy“.
Maybe now somebody can understand why entropy is a shadow.
And maybe now somebody will understand why
" The Law of conservation and transformation of energy"
is also correct for thermodynamic system.
f)
Why is " The second law of Thermodynamics"
so universal? Because it is based on
" The Law of conservation and transformation of energy"
And this law is not the simple accounting solution of debit and credit.
The sense of this law is dipper and it says more than is usually accepted.
==========.
Best wishes.
Israel Sadovnik. Socratus.