Wednesday, February 28, 2007
Wednesday, February 21, 2007
Further about neutron star and the core of collapsed matter!
Then, it follows that for the typical neutron star discussed earlier, the specific gravity of 5*10**14 yieds a critical radius of 4*10**9 km/sqrt(5*10**14) =180 km approx. Thus the neutron star still falls short of becoming a blackhole (10km radius as against the required 180km). For the collapsed core referred to earlier, the critical radius becomes 180/sqrt(2) km = 127 km, which too should be visible and not a blackhole unless a core of 127 km radius is achieved!
srini
Then, it follows that for the typical neutron star discussed earlier, the specific gravity of 5*10**14 yieds a critical radius of 4*10**9 km/sqrt(5*10**14) =180 km approx. Thus the neutron star still falls short of becoming a blackhole (10km radius as against the required 180km). For the collapsed core referred to earlier, the critical radius becomes 180/sqrt(2) km = 127 km, which too should be visible and not a blackhole unless a core of 127 km radius is achieved!
srini
Monday, February 19, 2007
Getting denser!
For gold, r(critical) becomes 0.7*10**9km (a shining blackhole!); for platinum, it is 0.55*10**9km.
Now going a bit celestial, the density of a neutron star is known to be in the range of 0.5*10**15gm/cc as they are supposed to contain one solar mass per ball of 20km diameter!
Still one takes the core at which gravitation collapses to a steady state, it is about 10**12 kg/cc or 10**15 gm/cc, said to be close to the density of a typical nucleus! i.e double that of a neutron star. Compare it with that of the neutron I had estimated to be! 5*10**136 gm/cc (at least).
srini
For gold, r(critical) becomes 0.7*10**9km (a shining blackhole!); for platinum, it is 0.55*10**9km.
Now going a bit celestial, the density of a neutron star is known to be in the range of 0.5*10**15gm/cc as they are supposed to contain one solar mass per ball of 20km diameter!
Still one takes the core at which gravitation collapses to a steady state, it is about 10**12 kg/cc or 10**15 gm/cc, said to be close to the density of a typical nucleus! i.e double that of a neutron star. Compare it with that of the neutron I had estimated to be! 5*10**136 gm/cc (at least).
srini
Wednesday, February 07, 2007
Critical radius calculation for a material of given density
r(critical) = 2*G*M / c**2 = 2 G * density * (4/3) *pi*r(critical)**3 / c**2;
r(critical) = sqrt(3*c**2/(8*G*pi*density) )= sqrt(2.7*10**16/(8*6.67*10**-11*3.14*density))
With density=1000kg/m**3 for water, r(critical) for water = 4*10**12m approx = 4*10**9km.
Now, it follows that given a value for the material density but assuming homogeneity, the critical value of radius at which the material in spherical form just becomes a blackhole. Further, the critical radius for any other material can be uniquely determined given its specific gravity, i.e. how much heavier than water it is. Taking the average value of specific gravity for our Earth as 5.5, the critical radius would then become 4*10**9 / sqrt(5.5) km = 1.7 * 10**9 km (approx).
In essence, the r(critical) varies with specific gravity in an inverse square root fashion.
With 11.6 for lead, r(critical) becomes about 1.2*10**9 km.
srini
r(critical) = 2*G*M / c**2 = 2 G * density * (4/3) *pi*r(critical)**3 / c**2;
r(critical) = sqrt(3*c**2/(8*G*pi*density) )= sqrt(2.7*10**16/(8*6.67*10**-11*3.14*density))
With density=1000kg/m**3 for water, r(critical) for water = 4*10**12m approx = 4*10**9km.
Now, it follows that given a value for the material density but assuming homogeneity, the critical value of radius at which the material in spherical form just becomes a blackhole. Further, the critical radius for any other material can be uniquely determined given its specific gravity, i.e. how much heavier than water it is. Taking the average value of specific gravity for our Earth as 5.5, the critical radius would then become 4*10**9 / sqrt(5.5) km = 1.7 * 10**9 km (approx).
In essence, the r(critical) varies with specific gravity in an inverse square root fashion.
With 11.6 for lead, r(critical) becomes about 1.2*10**9 km.
srini
Tuesday, February 06, 2007
SEARCH FOR EXTRA-TERRESTRIAL LIFE THROUGH RADIO, TV SIGNALS!
Astronomers plan to search 1000 nearby stars for television broadcasts and other signals that could indicate extra-terrestrial life, the Harvard-Smithsonian center said. The project planned for early 2008, would use a new radio telescope to search for radio traffic similar to that found on the Earth. Current efforts to find extra-terrestrial life look towards messages deliberately beamed across space – an approach that would miss any civilisation that does not advertise its existence as the Earth does. The new effort would search a portion of the electromagnetic spectrum used on the Earth for more mundane purposes – radar, television and FM radio broadcasts. It was hoped that spurious signals from people but not meant for us would be picked up according to the director of communications at the centre.
srini
Astronomers plan to search 1000 nearby stars for television broadcasts and other signals that could indicate extra-terrestrial life, the Harvard-Smithsonian center said. The project planned for early 2008, would use a new radio telescope to search for radio traffic similar to that found on the Earth. Current efforts to find extra-terrestrial life look towards messages deliberately beamed across space – an approach that would miss any civilisation that does not advertise its existence as the Earth does. The new effort would search a portion of the electromagnetic spectrum used on the Earth for more mundane purposes – radar, television and FM radio broadcasts. It was hoped that spurious signals from people but not meant for us would be picked up according to the director of communications at the centre.
srini
Monday, February 05, 2007
COSMIC REVELATION
Astronomers unveil detailed 3-D map of universe
A team of astronomers has unveiled a three-dimensional map that sheds light on the mysterious dark matter that makes up a quarter of the universe. The map shows that the dark matter forms a filamentous skeleton upon which visible matter congregates, eventually producing stars, Nature magazine has reported. The composition of the dark matter is unclear but it is believed that without it the universe could not exist. The dark matter is thought to act as glue, holding galaxies together. ‘This is the first time that such a large scale three-dimensional picture of dark matter has been produced, and it will allow cosmologists to probe deeper into the nature of this elusive matter”, the report said.
The map also has a few puzzles within it. Some areas show clumps of dark matter that aren’t accompanied by the bright features associated with conventional visible material (made of Baryonic matter) and vice versa.
“On the large scale, the general picture is as expected, but there are some small-scale discrepancies”, it was reported, based on the map synthesized from hundreds of slightly overlapping images from the Hubble space telescope’s cosmic evolution survey.
Astronomers unveil detailed 3-D map of universe
A team of astronomers has unveiled a three-dimensional map that sheds light on the mysterious dark matter that makes up a quarter of the universe. The map shows that the dark matter forms a filamentous skeleton upon which visible matter congregates, eventually producing stars, Nature magazine has reported. The composition of the dark matter is unclear but it is believed that without it the universe could not exist. The dark matter is thought to act as glue, holding galaxies together. ‘This is the first time that such a large scale three-dimensional picture of dark matter has been produced, and it will allow cosmologists to probe deeper into the nature of this elusive matter”, the report said.
The map also has a few puzzles within it. Some areas show clumps of dark matter that aren’t accompanied by the bright features associated with conventional visible material (made of Baryonic matter) and vice versa.
“On the large scale, the general picture is as expected, but there are some small-scale discrepancies”, it was reported, based on the map synthesized from hundreds of slightly overlapping images from the Hubble space telescope’s cosmic evolution survey.
“The existence of large clumps of isolated dark matter and visible matter flies in the face of everything we know”, according to a cosmologist from the University of Durham, U.K.
srini
Thursday, February 01, 2007
Supernova remnant RCW86 – Dating modified to AD 185
According to a recent study, the supernova remnant RCW 86 is much younger than previously thought, pointing towards a modified date of about AD 185. The formation of the remnant appears to coincide with a supernova observed by Chinese astronomers in AD 185. The study used data from NASA’s Chandra X-ray observatory and the European space agency’s XMM-Newton observatory. Previous suggestions to this effect have been confirmed by the new X-ray data, the lead author reported.
When a massive star runs out of fuel, it collapses on itself, creating a supernova that can outshine an entire galaxy. The intense explosion hurls the outer layers of the star into space and produces powerful shock waves. The remains of the star and the material it encounters are heated to millions of degrees and can emit intense X-ray radiation for thousands of years.
In the stellar work, the debris in RCW 86 was studied to estimate when its progenitor star originally exploded. It was also calculated how quickly the shocked or energized shell is moving in RCW 86, by studying one part of the remnant. Combining this expansion velocity with the size of the remnant and a basic understanding of how supernovas expand, led to the estimation of the age of RCW 86 afresh – as about 2000 years old.
The younger age for RCW 86 may explain an astronomical event observed almost 2000 years ago. In AD 185, Chinese astronomers (and possibly the Romans) recorded the appearance of a new bright star. The Chinese noted that it sparkled like a star and did not appear to move in the sky, arguing against it being a comet. Also, the observers noticed that the star took about eight months to fade, consistent with the modern observations of supernovas. However, uncertainties about the age provided significant doubt about the association.
The smaller age estimate for the remnant follows directly from a higher expansion velocity. By examining the energy distribution of the X-rays, a technique known as spectroscopy, the team found that most of the X-ray emission was caused by high energy electrons moving through a magnetic field. This is well known process that gives rise to low energy radio emission. However, only very high shock velocities can accelerate the electrons to such high energies that X-ray radiation is emitted. The difference in age estimates for RCW 86 is due to differences in expansion velocities measured for the supernova remnant. The authors speculate that these variations arise because RCW 86 is expanding into an irregular bubble blown by a wind from the progenitor star before it exploded. In some directions, the shock wave has encountered a dense region outside the bubble and slowed down, whereas in other regions the shock remains inside the bubble and is still moving rapidly. These regions give the most accurate estimate of the age.
srini
According to a recent study, the supernova remnant RCW 86 is much younger than previously thought, pointing towards a modified date of about AD 185. The formation of the remnant appears to coincide with a supernova observed by Chinese astronomers in AD 185. The study used data from NASA’s Chandra X-ray observatory and the European space agency’s XMM-Newton observatory. Previous suggestions to this effect have been confirmed by the new X-ray data, the lead author reported.
When a massive star runs out of fuel, it collapses on itself, creating a supernova that can outshine an entire galaxy. The intense explosion hurls the outer layers of the star into space and produces powerful shock waves. The remains of the star and the material it encounters are heated to millions of degrees and can emit intense X-ray radiation for thousands of years.
In the stellar work, the debris in RCW 86 was studied to estimate when its progenitor star originally exploded. It was also calculated how quickly the shocked or energized shell is moving in RCW 86, by studying one part of the remnant. Combining this expansion velocity with the size of the remnant and a basic understanding of how supernovas expand, led to the estimation of the age of RCW 86 afresh – as about 2000 years old.
The younger age for RCW 86 may explain an astronomical event observed almost 2000 years ago. In AD 185, Chinese astronomers (and possibly the Romans) recorded the appearance of a new bright star. The Chinese noted that it sparkled like a star and did not appear to move in the sky, arguing against it being a comet. Also, the observers noticed that the star took about eight months to fade, consistent with the modern observations of supernovas. However, uncertainties about the age provided significant doubt about the association.
The smaller age estimate for the remnant follows directly from a higher expansion velocity. By examining the energy distribution of the X-rays, a technique known as spectroscopy, the team found that most of the X-ray emission was caused by high energy electrons moving through a magnetic field. This is well known process that gives rise to low energy radio emission. However, only very high shock velocities can accelerate the electrons to such high energies that X-ray radiation is emitted. The difference in age estimates for RCW 86 is due to differences in expansion velocities measured for the supernova remnant. The authors speculate that these variations arise because RCW 86 is expanding into an irregular bubble blown by a wind from the progenitor star before it exploded. In some directions, the shock wave has encountered a dense region outside the bubble and slowed down, whereas in other regions the shock remains inside the bubble and is still moving rapidly. These regions give the most accurate estimate of the age.
srini
Thursday, December 21, 2006
Coming to density calculation!
If the radius of the neutron has just the critical value of 2x10**-54m (i.e. just a blackhole), the density becomes = 1.67x10**-27kg / ((4/3) 3.14 (2x10**-54m)**3) = 5x10**133 kg/m**3= 5x10**136 g/cc; i.e. a specific gravity of 5x10**136 (so many times heavier than water!).
If any other material cosisting of neutrons, protons, electrons and empty space could become a blackhole for a particular value of radius, the neutron could then be MUCH HEAVIER than as calculated above, especially if the empty space is of orders higher than the dimension of the neutron itself - oops! Now, shall we explore the above 'if', i.e. any other material can become a blackhole?
Let's have a break and meet soon!
srini
If the radius of the neutron has just the critical value of 2x10**-54m (i.e. just a blackhole), the density becomes = 1.67x10**-27kg / ((4/3) 3.14 (2x10**-54m)**3) = 5x10**133 kg/m**3= 5x10**136 g/cc; i.e. a specific gravity of 5x10**136 (so many times heavier than water!).
If any other material cosisting of neutrons, protons, electrons and empty space could become a blackhole for a particular value of radius, the neutron could then be MUCH HEAVIER than as calculated above, especially if the empty space is of orders higher than the dimension of the neutron itself - oops! Now, shall we explore the above 'if', i.e. any other material can become a blackhole?
Let's have a break and meet soon!
srini
Monday, November 20, 2006
My little neutron!
Continuing the calculations, putting the neutron mass as 1.67x10**-27kg, G=6.67x10**-11 and
c=3x10**8m/sec, the radius of the neutron for it be just a black hole needs to be just about 2x10**-54 metre or 2x10**-51 mm. Taking the diametre to be twice the radius, this gives about 2.5x10**50 neutrons stackable in a millimetre! In case the real blackholes contain empty space, the neutron could be much smaller!
srini
Continuing the calculations, putting the neutron mass as 1.67x10**-27kg, G=6.67x10**-11 and
c=3x10**8m/sec, the radius of the neutron for it be just a black hole needs to be just about 2x10**-54 metre or 2x10**-51 mm. Taking the diametre to be twice the radius, this gives about 2.5x10**50 neutrons stackable in a millimetre! In case the real blackholes contain empty space, the neutron could be much smaller!
srini
Thursday, November 09, 2006
Eureka! Eureka! Scientists discover new element - UNUNOCTIUM!
Just as the deliberation is going on about the densest material, there is some news (October 2006) that US and Russian scientists announced that they had discovered a superheavy element, known as 118, albeit one that has only existed in three different atoms lasting a fraction of a second over months of experiments. The last discovery of a naturally occurring element on the periodic table was in 1925 and have since sought to create new heavier elements. The last new elements discovered , 113 and 115, were announced in 2004.
Scientists said they found their first superheavy element 118 atom in 2002, then found another two atoms in 2005 in a second round of experiments in which they fired 10 to the power of 19 calcium ions at the californium. In the end the atoms of element 118 - also known as ununoctium - lasted 0.9 milliseconds, researchers said. But due to some controversies, this was not fully accepted. Adding a fresh lease of hope, in the latest experiments, scientists at the Lawrence Livermore National Laboratory in California and the Joint Institute for Nuclear Research in Dubna, Russia, bombarded Californium with Calcium ions to create 118 - the heaviest ever created in such experiments. 118 denotes the number of protons in the nucleus or the atomic number, technically speaking. It is said to fit just below Radon in the column of the periodic table containing what are called noble gases for their inert chemical properties.
Now the point I (the author of the blog) would like to add and highlight is that the solid form of the element 118 must be considered and that too at absolute zero temperature! I have an inkling that any material cooled to absolute zero could degenerate into a totally packed bunch of neutrons. Am I right? Any comments from our esteemed physicist-fratenity?
srini.
9 nov 2006
Just as the deliberation is going on about the densest material, there is some news (October 2006) that US and Russian scientists announced that they had discovered a superheavy element, known as 118, albeit one that has only existed in three different atoms lasting a fraction of a second over months of experiments. The last discovery of a naturally occurring element on the periodic table was in 1925 and have since sought to create new heavier elements. The last new elements discovered , 113 and 115, were announced in 2004.
Scientists said they found their first superheavy element 118 atom in 2002, then found another two atoms in 2005 in a second round of experiments in which they fired 10 to the power of 19 calcium ions at the californium. In the end the atoms of element 118 - also known as ununoctium - lasted 0.9 milliseconds, researchers said. But due to some controversies, this was not fully accepted. Adding a fresh lease of hope, in the latest experiments, scientists at the Lawrence Livermore National Laboratory in California and the Joint Institute for Nuclear Research in Dubna, Russia, bombarded Californium with Calcium ions to create 118 - the heaviest ever created in such experiments. 118 denotes the number of protons in the nucleus or the atomic number, technically speaking. It is said to fit just below Radon in the column of the periodic table containing what are called noble gases for their inert chemical properties.
Now the point I (the author of the blog) would like to add and highlight is that the solid form of the element 118 must be considered and that too at absolute zero temperature! I have an inkling that any material cooled to absolute zero could degenerate into a totally packed bunch of neutrons. Am I right? Any comments from our esteemed physicist-fratenity?
srini.
9 nov 2006
Tuesday, September 26, 2006
struggling to get to the answer? Let's try.
Under the above assumptions of incompressibility of the neutron etc., the neutron's density should be greater than or equal to that of the densest blackhole in the universe. Thus the radius of the (spherically assumed) neutron should be less than or equal to the critical radius at which the neutron just becomes a blackhole. The calculation should not be a problem, given the fact that the escape velocity at the surface of the neutron must equal the speed of light in vacuum.
r (critical) = 2 G M(neutron)/c**2.
Any answers? bye.
Under the above assumptions of incompressibility of the neutron etc., the neutron's density should be greater than or equal to that of the densest blackhole in the universe. Thus the radius of the (spherically assumed) neutron should be less than or equal to the critical radius at which the neutron just becomes a blackhole. The calculation should not be a problem, given the fact that the escape velocity at the surface of the neutron must equal the speed of light in vacuum.
r (critical) = 2 G M(neutron)/c**2.
Any answers? bye.
Sunday, July 30, 2006
Hello Homosapiens
This is to invite everybody interested in joining a perennial (!) chat / discussion with a view to seek / share knowledge about the universe in a scientific / logical manner. Although numerous textbooks / journals carry an ocean of information / knowledge in various fields, the communication is one way. Even conferences / symposia which allow interaction are limited in the effectiveness due to restriction in the audience addressed. A universal interacting network by post or ordinary mail would be snail paced. It is here that the advent of internet involving computer communications at electromagnetic speeds comes in handy with a free for all chatting / communicating through e-mail being made possible. The beauty is that the whole affair can be offline, with anyone needing to spend time only for his / her transaction from his / her place of choice. Many of us may be having some nagging doubts or even interesting ideas on basic as well as applied sciences or even engineering (material as well as human engineering), for which textbooks may not be sufficient. So, come on, homosapiens of worldwideweb, into the virtual world of brainstorming to unravel our universe.
Love all - for a lifelong wisdom game.
Yours truly,
B.SRINIVASAN.
Scientist / Engineer
Service: 1
Ever wondered which is (or could be) the heaviest or the densest material in the universe? I am eager to know from our scientists whether a test has been conducted in this direction. Which is the element in the periodic table eligible for this honour? Whether the candidate is an element in the first place or a compound? If it could be a compound, our mankind may not know all possible compounds. In cases of liquids and gases, one can think of the solid form, and if necessary, the density when cooled to absolute zero.
On one hand, it may appear as if it is not feasible to arrive at a conclusive answer, yet consider the following line of (my) thought:
Starting with the premise that all matter consists of protons, electrons and neutrons separated spatially, it follows that unless compressible, one of these particles must qualify as the densest fellow! I have an inkling that it must be a neutron! Getting to derive the mass of a neutron is not a big deal (=(molar mass of Deutarium (D2)-molar mass of Hydrogen (H2))/(2*avagadro number)), but what about its volume?
Ever wondered which is (or could be) the heaviest or the densest material in the universe? I am eager to know from our scientists whether a test has been conducted in this direction. Which is the element in the periodic table eligible for this honour? Whether the candidate is an element in the first place or a compound? If it could be a compound, our mankind may not know all possible compounds. In cases of liquids and gases, one can think of the solid form, and if necessary, the density when cooled to absolute zero.
On one hand, it may appear as if it is not feasible to arrive at a conclusive answer, yet consider the following line of (my) thought:
Starting with the premise that all matter consists of protons, electrons and neutrons separated spatially, it follows that unless compressible, one of these particles must qualify as the densest fellow! I have an inkling that it must be a neutron! Getting to derive the mass of a neutron is not a big deal (=(molar mass of Deutarium (D2)-molar mass of Hydrogen (H2))/(2*avagadro number)), but what about its volume?
If anyone has an authentic answer, welcome please.
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