6 replies to this topic

[kkala]

Universe birth and development stories have been chalming, so attached "cosmology in brief.doc" may be interesting, based on scientific data up to 2002. Wikipedia, a good further reference, indicates that only the "cyclic model" was introduced after 2002, which of course is not mentioned in the attached text. One has to read further books if interested, but the present could hopefully give a taste.

Attached Files

•  Cosmology in brief.doc   31KB   21 downloads

[kkala]

Below is additional information, as a supplement to “cosmology in brief” presented on 17 Nov 2011. It is pointed out that laws of physics & chemistry are valid all over Universe. For instance, value of gravity acceleration (g=9.81 m/s2 on earth) differs from planet to planet, resulting from gravity force exerted by each planet on 1 kg of mass (Weight=mass*g). But constant G=6.67E-11 Ntm2/kg2 of gravitational law is same all over Universe. Physical laws, along with mathematics and actual observations, help interpretation of phenomena and formation of theories.
1. Data for sun & earth.

Mass: Sun 2E30 kg, Earth 6E24 kg
Diameter: Sun 1400E6 m, Earth 12.74E6 m.
Average specific gravity (water = 1.0): Sun 1.4, Earth 5.5
Surface temperature: Sun ~6000 oK, Earth 288 oK.
Center temperature: Sun ~19E6 oK, Earth ~5700 oK

Specific gravity at center (water=1): Sun ~108, Earth ~13 (crust ~ 2.5).

Composition: Sun H=65%, He=30%, heavier elements=5% (varies per interpreting theory). Earth Fe=32%, Si+Mg=29%, O=30%, S=3%, other=6% (w/w).
Concerning Sun, temperature conditions are quite stable. All energy produced is emitted at a rate of 3.7E26 W (quasi-static process). Sun surface area is π*(1400Ε6)^2= 6.16E18 m2, and Stefan-Boltzmann law for black body radiation at 6000 oK predicts 5.67E-8*6000^4=73.48E6 W/m2. So heat radiated from Sun (all wavelengths) is estimated at 6.16E18*73.48E6=4.5E26 W, little differing to published 3.7E26 W.

1.1 Due to extremely high temperatures, sun’s matter behaves as an ideal gas composed of particles (nuclei & electrons). According to this principle:

⁵⁶₂₆Fe is composed of 1 nucleus & 26 electrons, avg atomic weight As= 56/27=2.07.

¹⁶₈O is composed of 1 nucleus & 8 electrons, As= 16/9=1.8

Average atomic weight of all particles (except from H & He) As~ 2.0
¹₁H is composed of 1 nucleus & 1 electron, avg atomic weight As= 1:2=0.5

⁴₂He is composed of 1 nucleus & 2 electrons, As= 4/3=1.3
Average atomic weight of all sun particles As~1.0.
If temperature & pressure were uniform, above data would give P/T=116 bar/oK (R=0.083145 m3bar/oK/kgat). This is indicative of the huge pressures inside sun, where gravity is balanced off by thermal collisions of particles.
For a star to be thermally stable, its mass should approximately be > 0.5*M (otherwise no shine) and <5*M (otherwise it shall explode), where M = Sun mass (2E30 kg). Common stars have mass <2*M and temperatures close to that of Sun.
For stars similar to Sun, temperature is proportional to mass and inverse to diameter. E.g. Sirius with mass 2.4*M and diameter 1.8 of Sun, would have temperature in oK 2.4/1.8=1.3 times that of Sun.

1.2 Sun is generating heat by thermonuclear fusion of H at 10E6 oK ( http://en.wikipedia.org/wiki/Star). H is converted into He at a rate of about 180E9 kg/s to generate the emitted heat, as attached “sunfusion.xls” indicates.
Heat generation mechanism changes to He conversion into C (at 100E6 oK), when the star gets a Red Giant at the end of its life, as it shall occur with Sun after ~5E9 years. Even in that age, there can be periods of “temporary” reverting to H fusion ( http://en.wikipedia.org/wiki/Red_giant).

2. Sundry info of recent years.

2.1 Few scientists have expressed concern that particle collisions implemented by strong modern accelerators (e.g. Kern Collider in Switzerland) could create a new Universe! The answer by RAM (main reference of previous post) was that what has not been created in 12 billion years is quite improbable to happen now. Another article in the bulletin of Technical Chamber of Greece suggests that accelerated particles do not have energy adequate to initiate such a formation.

2.2 As previous post says (17 Nov 11), even black holes can be “evaporated” withing huge time intervals (e.g. 1E60 years) through Hawking radiation emitted from them. Co-existence of a particle with its antiparticle is probable everywhere, even in the vicinity of black hole. But there the two virtual particles accept energy and become “real”. In case that the antiparticle falls inside and the particle outside, the black hole has already lost some energy. Due to stronger gravity, big black holes are “evaporated” more slowly than small ones.

2.3 The cyclic model of an oscillating Universe (expanding, then contracting, and so on) was expressed in 1930s. The big bang would be followed by the big crunch. The idea was abandoned, but revived recently in more complex versions, one of which estimates a cycle period at ~1E12 years. It is related to dark energy, an unknown form of energy to rule Universe. More on http://en.wikipedia...ki/Cyclic_model.

Note: Above is collected from school physics, as well as "New Encyclopaedia of Helios" (in Greek) - "The Universe" (Athens, ~1979).

Wikipedia is again a good reference for supplementary info.

Attached Files

•  sunfusion.xls   24KB   11 downloads

Edited by kkala, 23 November 2011 - 05:09 PM.

This is extremely interesting to me, thanks so much for sharing the files!

[kkala]

When in late 1950s the first satellites were placed, there was a booming interest about cosmology. Common magazines were writing about expanding universe, electrons, neutrons, etc, exciting minds of children. That confused idea was the incentive to write something, even though public interest in the subject and the exploration of space has been declined. The last strong emotion was due to Challenger accident in 1986.
For Chemical Engineers cosmology is within their theoretical interests. Stars produce energy through nuclear fusion. Sun and planets reminds nucleus and electrons.

Edited by kkala, 23 December 2011 - 06:32 PM.

[Absolute Zero]

Very Nice information shared, please also discuss the concept of gravitational lens if you have any material on that topic, because it is really interesting topic in astro physics

[kkala]

Unfortunately I was not aware of the gravitational lensing, hopefully some other member could give the essence of the topic. Wikipedia is usually a good source for cosmological info, look in this case at http://en.wikipedia....vitational_lens.
It was surprising to know as a student that light traveling in the proximity of Sun has a slighly curved flight, indicating that photons (http://en.wikipedia.org/wiki/Photon) can behave as particles of very small mass.

[kkala]

For those interested in astronomical observations, http://www.eso.org/public/ may be a good site, with a lot of exciting pictures of universe. They have several telescopes in Chile, in places of high altitude and minimum humidity.
To my information, space telescopes was the last word of technology some years ago. Now these telescopes on earth manage to have a clear picture, using interferometry, as explained in http://en.wikipedia..../Interferometry.