Universe Related Sites of Interest:
Image courtesy of Scientific American August 2014 Volume 311, Number 2 The Black Hole at the Beginning of Time
If the assumptions of homogeneity and isotropy are valid and the current formulation of general relativity according to the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric is correct, it is unavoidable that the Universe began in an infinitely dense state not more than 14 billion years ago (the Big Bang) and has been expanding ever since.
A slightly different alternative view is that the singularity of a black hole in the 4th dimension is the singularity of a Big Bang in the 3rd dimension that created a new parallel bubble universe (ours).
Universe Related Sites of Interest:
Estimated Parameters of the universe includes the following:
| Universe Time | Red Shift (z) | Temperature T(K) | Event |
|---|---|---|---|
| ~10-34sec | ~10-27 | 1027 | Inflation ends, causally connected regions have expanded exponentially, initial fluctuation spectrum determined. |
| 2 seconds | 4x109 | 1010 | Neutron freezeout, no more neutrons formed. |
| 3 minutes | 4x108 | 4x109 | Primordial nucleosynthesis over - light element abundances set. |
| 65,000 years | 3500 | 104 | Radiation domination → mass domination, R≈t½→t2/3, dark-matter structures start growing at a significant rate. |
| 380,000 years | 1100 | 3000 | H atoms recombine, matter and radition decouple, Universe becomes transparent to radiation of wavelengths longer than Lyα, CMB flux pattern frozen in space, baryon perturbations start growing. |
| ~108-109 yr | ~6-20 | ~20-60 | First stars form and reionize the Universe, ending the Dark Ages. The Universe becomes transparent to radiation with wavelengths shorter than a Lyα. |
| ~6 Gyears | ~1 | ~5 | Transition from deceleration to acceleration under the influence of Dark Energy. |
| 14 Gyears | 0 | 2.725±0.002 | Today. |
We can estimate the main sequence lifetime of a star based on the stellar mass. The more massive the star, the shorter its hydrogen burning phase on the main sequence, as follows:
Galaxies of all types come in a range of luminosities, masses, and sizes.
About 25% of a galaxy's mass consists of what is believed to be what is called dark matter. It could consist of the following forms:
Gravitational lensing has convinced most cosmologists that MACHOs cannot make up more than a small fraction of dark matter.
A stellar remnant with a mass above the maximum amount allowed of a neutron star will cause a complete collapse of the stellar remnant to a singularity, or black hole. As the name implies, neither radiation nor matter may escape from a black hole.
Neutron Star Collision, click here
Black Hole Collision, click here
There is evidence for the existence of supermassive black holes, with masses of 106 to 109 masses of the Sun to exist in the centers of most large galaxies.
Einstein's General Theory of relativity predicted gravitational waves in 1916, but they were not discovered until
September 14, 2015 when the newly completed Laser Interferometer Gravitational-Wave Observatory (LIGO - GW151226) detected them when
two colliding massive black holes 36 and 29 times as massive as the sun merged perturbing space-time several billion light years ago.
A second detection (GW151226) matched the prediction for the coalescence of two black holes of 14.2 and 7.5 solar masses.
The Drake Equation is used to estimate the number of technological civilizations that might exist among the stars.
While working as a radio astronomer at the National Radio Astronomy Observatory in Green Bank,
West Virginia, Dr. Frank Drake conceived an approach to bound the terms involved in estimating the number of technological
civilizations that may exist in our galaxy. The Drake Equation, as it has become known, was first presented by Drake in 1961
and identifies specific factors thought to play a role in the development of such civilizations. Although there is no unique
solution to this equation, it is a generally accepted tool used by the scientific community to examine these factors.
N = the number of civilizations in our galaxy with which communication might be possible.
R* = the average rate of star formation in our galaxy.
fp = the fraction of those stars that have planets.
ne = the average number of planets that can potentially support life per star that has planets.
fl = the fraction of planets that could support life that actually develop life at some point.
fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations).
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space.
L = the length of time for which such civilizations release detectable signals into space.
To see more details about the Drake Equation, visit here
Author:
Mitchell Wagner (E105 fall of 1997)
The Drake Equation:,
N = R* · fp · ne · fl · fi · fc · L
Explanation of Variables:
N represents the total number of technolgically advanced civilizations in the Milky Way who's
radio transmissions are detectable on Earth.
R* represents the rate of star formation in a given galaxy. The star being formed must have
a long enough lifespan for intelligent life to evolve.
fp represents the fraction of the stars formed that have planets in stable orbits. Presently
with to techniques in observation there have been numerous planets discovered orbiting other
stars, so this trem is now generally accepted at being at 1.0 or very close to it. Perhaps in
the range of 0.8 - 1.0.
ne represents the number of Earth-like planets. With regard to "Earth-like" we mean planets in
an orbit at a given distance that is in the same proportion to the size of the star. For example,
we take the Mass of our sun and divide it by the distance between the Earth and the sun.
fl represemts the fraction of the above planets that that are capable of supporting life. For
this term we take our solar system as a model. With nine planets and one that is "Earth-like"
and we get a fraction in the range 0.1 - 0.15.
fi represents the fraction of those planets on which intelligent life evolves. This is one of
the terms about which there is a great deal of discussion. Some argue that Earth is the only
planet on which life evolved. Others argue that intelligent life is quite common. So for this
term the range could be from a very small fraction all the way to 1.0.
fc represents the fraction of the intelligent which evolve the ability to communicate.
Specifically using radio wave emissions which can be detected from a distance. We know from
our own planet that the are various intelligent species (Dolphins and primates) but not all
develop the ability to use radio waves as a means of communication. So this term can also
range from a very small fraction to slightly less than 1.0.
L represents the estimated average lifetime of an intelligent civilization that that has
the ability to communicate using radio waves. Once again using our own society as a model
we can use then number of years we have been technilogically advanced. For example we can
just use something in the range 100 - 200 years.
Sample Data:
The table below shows possible values for the seven terms. Also displayed is the the final
total of advanced civilizations calculated from the seven terms. In the below table we use
the value of 10 and 100 as the rates of star formation which seems to be consistent from the
observational data from the age of the stars in out galaxy. For the term fp we use the value
of 0.5 as an estimate of the fraction of stars with orbiting planets. One half is probable a
rather liberal estimate. For the term L we use several values, varying in range from 100 - 10000
years. For the term ne we use the value 1. The rational for this is that a given star's habitable
zone is only large enough for one planet, as in our own solar system. The rest of the terms fl, fi
and fc are all set with the value of 0.1. We choose this value for simplicity's sake. These values,
in most cases, will be much less than they are here, but unfortunately there is a large degree of
uncertainty on the values.
N (# of civilizations)
R* fp ne fl fi fc L (years)
50 10 0.5 1.0 0.1 0.1 0.1 10000
5 10 0.5 1.0 0.1 0.1 0.1 1000
2.5 (3) 10 0.5 1.0 0.1 0.1 500
1 10 0.5 1.0 0.1 0.1 0.1 200
0.5 (1) 10 0.5 1.0 0.1 0.1 100
500 100 0.5 1.0 0.1 0.1 0.1 10000
50 100 0.5 1.0 0.1 0.1 0.1 1000
25 100 0.5 1.0 0.1 0.1 0.1 500
10 100 0.5 1.0 0.1 0.1 0.1 200
5 0.5 1.0 0.1 0.1 0.1 0.1 100
Conclusion:
The Drake Equation has been a relatively useful in estimating the number of
civilizations. Although, there has been a great deal of debate on the values of
several of the terms in the equation. Some scientists have derived values to give
us the long held value of N as 1.0. Other scientists have derived values which yield
many hundreds-of-thousands of civilizations, most notably, the late Carl Sagan. It is
my belief that the terms fi and fc are automatically going to be relatively high (i.e.)
close to 1.0) because given enough time, if life evolves, I am sure that the life will
eventually become both intelligent and develop the technology to communicate using various
technologies especially Radio waves as well as other Electromagnetic carrier waves.
Electromagnetic carrier waves, since they move at the speed of light, make the best means
of communication. They can be used to communicate between local (infra-planetary) "individuals"
as well between foreign (inter-planetary) "individuals". But ultimately only future advances in
observational techniques as well as technologies will aide in the search of both more accurate
values for these seven terms and for extraterrestrial intelligence.
Instructions:
Input values into variable fields.
Fields R*, Ne and L are all whole integers greater than 1.0.
Fields fp, fl, fi and fc must be less than 1.0.
Press Calculate.
Field N will display the total number of advanced civilizations.
To see the Drake Equation in action, click here
Here are the main observational methods that are used to detect and characterize extra-solar planets.
Astrophysics Related Constants