evolution of science:prehistoric period:part I

Evolution of science:

As humans evolved so do science, ofcourse we didnt know E=mC^2 out of the blue, science evolve by trial and error method.there were times when we thought earth is on top of a gaint turtle, and lunar eclipse is nothing but a wolf swallowing the moon.

we made our mistake, learned from it and now we are colonizing in mars.

scientific curiousity started when humans looked up in the sky and wondered the workings of it.

Ancient Chinese astrologers, by 2300 BC, already had sophisticated observatory buildings and as early as 2650 BC, Li Shu was writing about astronomy. Observing total solar eclipses was a major element of forecasting the future health and successes of the Emperor, and astrologers were left with the onerous task of trying to anticipate when these events might occur. Failure to get the prediction right, in at least one recorded instance in 2300 BC resulted in the beheading of two astrologers. Since the pattern of total solar eclipses is a very erratic one in time at a specific geographic location, many astrologers no doubt lost their heads. By about 20 BC, surviving documents show that Chinese astrologers understood what caused eclipses, and by 8 BC some predictions of total solar eclipse were made using the 135-month reoccurrence period. By 206 AD they could predict solar eclipses by analyzing the motion of the moon itself.


While Chinese, Babylonian and Greek astrologers dominated the astronomical knowledge of the 'Old World', half way across the globe, Maya observers were also working on calendars, and recording celestial observations to their own ends. The Dresden Codex records several tables which are widely thought to be lunar eclipse tables. As many civilizations had before them in other parts of the world, the Mayas used records of historical lunar eclipses to identify how often they occur over a 405 month period. There is no mention of recorded total solar eclipses, or discussions in the Codex for how to predict these events. After the conquest by the Spanish Conquistadors and the intentional destruction of nearly all native written records by the Missionaries by the 1600s, little survives today to tell us whether the Mayas, Incas or Aztecs had achieved a deeper understanding of solar eclipses and their forecasting.

Why the interest in eclipses?

One of the first things that civilizations must do to insure a coherent society, and the harvesting and planting of crops, is to establish an accurate calendar. Most of the early calendars were lunar 'monthly' calendars, but since the time between like lunar phases is 29.5 days, this only leads to 12.38 months during a solar ( seasonal) year, so that every year, the lunar calendar slips by 11 days relative to the seasonal 'planting' year. While establishing an accurate luni-solar calendar, ancient peoples observed the moon quite regularly, and over time would discover evenings when the moon was eclipsed by the Earth's shadow. Because the Earth's shadow is so vast, lunar eclipses were the first major celestial events that ancient astrologers would learn how to predict by using local historical observational records.

Why no solar eclipse predictions?

The diameter of the Earth's shadow at the distance of the Moon is over 12,000 kilometers across. This makes predicting lunar eclipses a very forgiving enterprise even when you do not know the precise details of the orbit of the Moon. For total solar eclipses, however, the shadow of the Moon upon the Earth's surface is only about 300 km across. At the distance of the Moon's orbit, this subtends an angle of less than 1/20 of a degree of arc. To forecast a solar eclipse, you would need to know the details of the lunar orbit to at least this degree of accuracy. With the exception of the ancient Chinese and Greeks, there are no written records that suggest that the Moon, stars or planets were routinely measured with this degree of accuracy. Some have proposed that many ancient civilizations kept track of when total solar eclipses occurred, and that from these local historical records, numerical patterns allowed ancient astrologers to make total solar eclipse forecasts. This also seems not to be possible.

                                                                                               ----THE PHYSICIST

First images of LHC collisions at 13 TeV

Last night, protons collided in the Large Hadron Collider (LHC) at the record-breaking energy of 13 TeV for the first time. These test collisions were to set up systems that protect the machine and detectors from particles that stray from the edges of the beam.




A key part of the process was the set-up of the collimators. These devices which absorb stray particles were adjusted in colliding-beam conditions. This set-up will give the accelerator team the data they need to ensure that the LHC magnets and detectors are fully protected.



Today the tests continue. Colliding beams will stay in the LHC for several hours. The LHC Operations team will continue to monitor beam quality and optimisation of the set-up.





This is an important part of the process that will allow the experimental teams running the detectors ALICE, ATLAS, CMS and LHCb to switch on their experiments fully. Data taking and the start the LHC's second run is planned for early June.


for more updates on cern: http://home.web.cern.ch/about/updates


                                                                                                                            ---THE PHYSICIST

exploded star are confirms supercomputer model predictions

New observations of a recently exploded star are confirming supercomputer model predictions made at Caltech that the deaths of stellar giants are lopsided affairs in which debris and the stars' cores hurtle off in opposite directions.


While observing the remnant of supernova (SN) 1987A, NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, recently detected the unique energy signature of titanium-44, a radioactive version of titanium that is produced during the early stages of a particular type of star explosion, called a Type II, or core-collapse supernova.


"Titanium-44 is unstable. When it decays and turns into calcium, it emits gamma rays at a specific energy, which NuSTAR can detect," says Fiona Harrison, the Benjamin M. Rosen Professor of Physics at Caltech, and NuSTAR's principal investigator.


By analyzing direction-dependent frequency changes--or Doppler shifts--of energy from titanium-44, Harrison and her team discovered that most of the material is moving away from NuSTAR. The finding, detailed in the May 8 issue of the journal Science, is the best proof yet that the mechanism that triggers Type II supernovae is inherently lopsided.


NuSTAR recently created detailed titanium-44 maps of another supernova remnant, called Cassiopeia A, and there too it found signs of an asymmetrical explosion, although the evidence in this case is not as definitive as with 1987A.


Supernova 1987A was first detected in 1987, when light from the explosion of a blue supergiant star located 168,000 light-years away reached Earth. SN 1987A was an important event for astronomers. Not only was it the closest supernova to be detected in hundreds of years, it marked the first time that neutrinos had been detected from an astronomical source other than our sun.


These nearly massless subatomic particles had been predicted to be produced in large quantities during Type II explosions, so their detection during 1987A supported some of the fundamental theories about the inner workings of supernovae.


With the latest NuSTAR observations, 1987A is once again proving to be a useful natural laboratory for studying the mysteries of stellar death. For many years, supercomputer simulations performed at Caltech and elsewhere predicted that the cores of pending Type II supernovae change shape just before exploding, transforming from a perfectly symmetric sphere into a wobbly mass made up of turbulent plumes of extremely hot gas. In fact, models that assumed a perfectly spherical core just fizzled out.


"If you make everything just spherical, the core doesn't explode. It turns out you need asymmetries to make the star explode," Harrison says.


According to the simulations, the shape change is driven by turbulence generated by neutrinos that are absorbed within the core. "This turbulence helps push out a powerful shock wave and launch the explosion," says Christian Ott, a professor of theoretical physics at Caltech who was not involved in the NuSTAR observations.


Ott's team uses supercomputers to run three-dimensional simulations of core-collapse supernovae. Each simulation generates hundreds of terabytes of results--for comparison, the entire print collection of the U.S. Library of Congress is equal to about 10 terabytes--but represents only a few tenths of a second during a supernova explosion.


A better understanding of the asymmetrical nature of Type II supernovae, Ott says, could help solve one of the biggest mysteries surrounding stellar deaths: why some supernovae collapse into neutron stars and others into a black hole to form a space-time singularity. It could be that the high degree of asymmetry in some supernovae produces a dual effect: the star explodes in one direction, while the remainder of the star continues to collapse in all other directions.


"In this way, an explosion could happen, but eventually leave behind a black hole and not a neutron star," Ott says.


The NuSTAR findings also increase the chances that Advanced LIGO--the upgraded version of the Laser Interferometer Gravitational-wave Observatory, which will begin to take data later this year--will be successful in detecting gravitational waves from supernovae. Gravitational waves are ripples that propagate through the fabric of space-time. According to theory, Type II supernovae should emit gravitational waves, but only if the explosions are asymmetrical.


Harrison and Ott have plans to combine the observational and theoretical studies of supernova that until now have been occurring along parallel tracks at Caltech, using the NuSTAR observations to refine supercomputer simulations of supernova explosions.


"The two of us are going to work together to try to get the models to more accurately predict what we're seeing in 1987A and Cassiopeia A," Harrison says.


Story Source:


The above story is based on materials provided by California Institute of Technology. The original article was written by Ker Than. Note: Materials may be edited for content and length.






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