Astronomical DISTANCES - how to measure them?

-   2532  -  Astronomical DISTANCES  -  how to measure them?  -  Measuring distances in astronomy is a very difficult process.  Many of the prior reviews have covered specific methods in some detail.  In this review I have put several methods all together to step by step reach galaxies at the edge of the Universe.  I have used half a dozen of the over two dozen distance measuring methods used by astronomers.  We start with the simplest.  Plain trigonometry.
-
-

-
-------------------- 2532  -  Astronomical DISTANCES  -  how to measure them?
-
-  OUT TO 200 LIGHTYEARS:  We start by measuring the angle to a nearby star in relation to its more distant background stars.  Then six months later when the Earth is on the other side of the Sun we measure the angle again. The angle will change. The nearby star will have shifted relative to its background stars due to parallax.
-
-   The same occurs when you extend your hand and view you thumb with one eye then the other and the background scenery shifts due to parallax.  The sine of the parallax angle = the opposite side / hypotenuse.  The opposite side of the right triangle is the distance between the Sun and the Earth and the hypotenuse is the distance to the star. 
-
-   PARALLAX EXAMPLE :  The closest star is Proxima Centauri.  The six month parallax angle was measured to be 0.76 arc seconds.  There are 3600 arc-seconds in 1 degree.  0.76 arc-seconds = 2.11*10^-4 degrees.  The sine of the parallax angle is 3.685*10^-6  The distance from the Sun to the Earth is 1.5*10^11 meters.
Distance to Proxima Centauri  =  (1.5*10^11) / (3.685*10^-6)  =  4.1*10^16 meters
1 lightyear = 9.46*10^15 meters  Distance to Proxima Centauri  =  4.3 lightyears, our closest star.
-
-  Next we measure the brightness of the star in watts / meter^2 (F) where we know the distance (D).  Now we can calculate the intrinsic luminosity (L) of the star.
-
---------------------  L  =  4*pi * D^2 * F
-
---------------------  where:   4*pi * D^2 is the surface area of a sphere of radius D
-
--------------------  where:  “F” is the Flux, or apparent luminosity, or brightness of the star that we measured.
-
-------------------  where:  “L” is intrinsic luminosity of the star. 
-
-   LUMINOSITY EXAMPLE: L  =  4*pi*D^2 * F
-
------------------  where:  F is the Flux we measured to be 1*10^-12 watts/m^2
-
 -------------------  where L = 3.8*10^26 watts, the same luminosity as our Sun.
-
-----------------  therefore: D  =  5.5*10^18 meters, or 581 lightyears
-
-  OUT TO 100,000 LIGHTYEARS:  Next we find a star in a more distant galaxy that is similar, and we can assume that it has the same intrinsic luminosity.  We measure its Brightness, F and calculate the distance D using the same formula:
-
--------------------------------------  D^2  = L / 4*pi*F
-
-  Next, rather than use a single star that we think is similar we measure the brightness of dozens of stars and plot them versus their temperature, or color.  This plot is called the   H-R diagram, the Hertzsprung - Russell diagram.  Luminosity versus temperature plots the stars of various masses that are on the Main-Sequence which is a straight line on this H-R graph. 
-
-  Luminosities range from 10^-3 to 10^5 Solar Luminosities.  Temperatures range from 30,000 Kelvin to 3,000 Kelvin, corresponding to colors from Blue to Red..  The size of the stars range from 0.1  to 10 Solar Radius. 
-
-  We do this straight line plot for stars in a galaxy where we know the distance (Hyades Cluster).  Next, we create a similar plot for stars in a galaxy where we want to find the distance (Pleiades Cluster).  Wien’s law is used to measure temperature by measuring the wavelength of maximum brightness.  Temperature = 00029 m*K / wavelength max.  Now we have two straight line Main-Sequence plots that shift in dimness for the more distant galaxy.  The distance squared is equal to the shift in brightness. 
-
-   STAR CLUSTER EXAMPLE: The Hyades Cluster of stars can be measured using the parallax method to have a distance of 151 lightyears.  We would like to calculate the distance to the Pleiades Cluster of Stars know as the Seven Sisters.  We measure the brightness and temperature of 50 stars in the Hyades Cluster and plot a Main-Sequence line.  The relative brightness ranges from 0.1 to 50.  The temperature ranges from 4000 to 8000 Kelvin.  Next, we do the same thing for 50 stars in the Pleiades Cluster.  The Main-Sequence straight line is shifted to 7.5 times dimmer than the straight line for the Hyades Cluster.  That means that it is the square root of 7.5 further distant away.  2.75 times 151 lightyears = 415 lightyears away for the Pleiades Cluster.
-
-  OUT TO 100,000,000 LIGHTYEARS:  Among the stars in a galaxy of known distance we find pulsating stars called Cepheids.  The period of pulsation of these Cepheid Stars is directly proportional to their intrinsic luminosity, L.  Once we calibrate this relationship we find Cepheids in a more distant galaxy.  Measuring the periods of pulsation we can determine their intrinsic luminosity, measure their brightness and calculate their distance:
-
---------------  D^2  =  L cepheid / F * 4*pi
-
-   CEPHEID EXAMPLE:    50 Cepheids are measured with pulsations from 1 to 100 days.  The brightness measured and the luminosities calculated because the distance is known.  Luminosities range from 1000 to 30,000 Solar Luminosity.  The straight line plot has the equation:  Luminosity  =  320*(Period) + 575. To measure the distance to  the M100 galaxy in the Coma Berenices three Cepheid Stars are found to have periods of:
-
------- Periods -----Solar -------  Luminosity -------  Brightness----- Distance
-------  Days ----- Luminosity-------  watts --------  watts/meter-----   MLY
-
------- 30 ---------  10,300-------  3.9*10^30  -----  9.3*10^-19 -------- 61
-
-------  8 ---------  3,100---------  1.2*10^30  -----  3.8*10^-19 -------- 53
-
------- 19---------  10,300-------  3.9*10^30  ------  8.7*10^-19 -------- 51
-
-  Note that our calculations vary by 55 + or - 5 million lightyears.  The galaxy is probably only a few hundred lightyears across so the error in our distance measurement is + or - 10%.  These are not very accurate distance measurements.
-
-  Besides the Cepheids in the Large Megellanic Cloud galaxy another fortunate occurrence happened in 1987.  A supernova exploded.  Previous pulsations before the explosion had created a shell of gas around the star.  When the star exploded the ultraviolet light took 240 days to reach the shell and light up the gas. 
-
-  The radius of the ring was measured to be 0.858 arc seconds.  That distance would be the speed of light * the 240 days  =  6.2*10^15 meters.  The sine of the angle 0.858 arc seconds = 4.12^10^-6.  The distance to the star is calculated to be 1.5*10^21 meters, which is 150,000 lightyears.  This gives astronomers a better calibration on the luminosity of the Cepheids and the luminosity of the supernova.
-
-  OUT TO 10,000,000,000 LIGHTYEARS:  Next we find a supernova explosion in a galaxy still farther away.  To know the intrinsic luminosity it must be a certain type of supernova, called a white dwarf supernova.  Supernovae are much brighter than Cepheid stars and can be measured at much greater distances.
-
-   The peak luminosity of the supernova is 10^10 Solar Luminosity and it remains above 10^8 for 150 days.  A typical Cepheid star is 10^4 Solar Luminosity.  We can measure the brightness of Cepheids out to 100 million lightyears.  Using the inverse distance squared formula this means we can measure supernova out to 10^11 lightyears, 100 billion lightyears.  The Observable Universe is 10^10 or 10 billion lightyears.  Therefore, astronomers should be able to measure distances out to the edge of the Universe.
-
-  OUT TO 13,700,000,000 LIGHTYEARS:  After measuring the distances to many galaxies, Edwin Hubble noted the correlation of distance with recession velocity.  Recession velocities were measured using the redshift of the galaxies light spectrum.  Plotting distances of 200 to 1,600 million lightyears versus receding velocities measured from 25,000 to 35,000 km/sec. resulting in a straight line with a constant slope of 22,000 km/sec per million lightyear.  This is known as Hubble’s Constant.  It defines the rate of expansion of the Universe.  Galaxies will be traveling faster by 22,000 km/sec, (49,000 miles per hour) for every million lightyears distant they are away from us. 
-
-   HUBBLE EXAMPLE:  We know the hydrogen emissions line in the light spectrum is at 656.3 nanometers. We measure this in three different galaxies and it has shifted to the red end of the spectrum.  Redshift = z =  (measured wavelength  -  656.3) / 656.3
For redshifts much less than 1 the velocity = speed of light * z.  The receding velocity divided by 22,000 km/sec per million lightyears gives the distance in million lightyears.
-
---------------Emission  -----  Redshift   ------- velocity  ------------  Distance
-----------  Wavelength  ---------  z  ----------- million mph--------  lightyears
-
------------659.6 nm  ---------  .005  -----------  3.4  ------------------ 690,000
-
------------664.7 nm  ---------  .013  -----------  8.6  ---------------- 1,750,000
-
------------6679.2 nm  -------  .035 -----------  23.4  ---------------- 4,760,000
-
-  The last amazing thing about the Hubble Constant for the expansion of the Universe is that lightyears are also time as well as distance.  And, if we run time backwards we can determine when the expansion started. 
-
-  The reciprocal of the Hubble Constant will give us the age of the Universe, assuming the expansion rate has always been the same:
-
-------------  1/ 22,000 km/sec/ MLY  =  1.36*10^10 years.  The age of the Universe is 13.6 billion years.  And, the distance to the edge of the Observable Universe is 13.6 billion lightyears.
-
-  Well,  now you have extended your knowledge to the edge of he Universe.  Well done.
-
-  December 9, 2019                                                            2532        863                                                                                     
----------------------------------------------------------------------------------------
-----  Comments appreciated and Pass it on to whomever is interested. ----
---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 
--  email feedback, corrections, request for copies or Index of all reviews
---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------
-  https://plus.google.com/u/0/  -- www.facebook.com  -- www.twitter.com
 ---------------------          Sunday, December 15, 2019    --------------------
-----------------------------------------------------------------------------------------

DIMENSIONAL ANALYSIS - how hot was the Big Bang?

-   2543  -  DIMENSIONAL  ANALYSIS  -  how hot was the Big Bang?  -  It turns out that plotting temperature versus pressure we get a straight line all the way back to the Big Bang.  Therefore, we should be able to use the laws of physics and extrapolate back to the Big Bang to determine how hot it was.  The math used is called “dimensional analysis.”
---
-
-

---------------- 2543  -  DIMENSIONAL  ANALYSIS  -  how hot was the Big Bang?
-
-  The temperature of the Universe is inversely proportional to its size.  As the Universe expands the temperature decreases.  Today it has expanded and cooled to a temperature of 2.725 degrees Kelvin.  That is 2.725 degrees above Absolute Zero.
-
-  What would happen if we reversed the expansion and sent time collapsing back to the Big Bang.  The temperature would get hotter and hotter.  The pressure would get greater and greater.
-
-  It turns out that the temperature / pressure relationship is a linear relationship.  Plotting temperature versus pressure we get a straight line all the way back to the Big Bang.  We will use the laws of physics and extrapolate back to the Big Bang to determine how hot it was.
-
-   The math used is called “dimensional analysis.”  It is a simple concept.  But, it is very powerful.  To learn it we will try it out on a pendulum before we try it out on the Universe.  Start small, go big.
-
-  Measurements in physics and astronomy can involve 3 dimensions:  length (space), time, and mass (energy).  We refer to these as dimensions and they are measured in units: meters, seconds, kilograms.
-
-   Starting with the pendulum let’s use these three dimensions to calculate the period of the pendulum swing.  The pendulum is a mass hanging freely on a string and swinging back and forth.  The period is the time for one cycle of one swing.
-
-  The period is “time“, it is possibly a function of  the three dimensions ,length, time, and mass to some degree.  The force on the mass is a function of gravity.  If we are on the surface of the Earth the acceleration of gravity is 9.8 meters / second^2  ( 32 feet per second per second.).  We might also guess that the period might be a function of the length of the string, and the weight of the mass.  Guess:
-
------------------  Time  =  mass  *  length  *  acceleration of gravity
-
----------------  Acceleration of gravity  = “g”    = (length  /  time ^2)  =  (m / sec^2)
-
--------------  Working with the units of each dimension, try to derive the equation for the period of a pendulum:  To get to the equality seconds  =  seconds.
-
---------------   second  =  kilograms  *  meters  *  meters / second^2
-
----------------  Working to cancel the units on the right side of the equation to equal the left side of the equation, which is seconds.  Let’s divide by the acceleration of gravity , (meters / seconds^2)^-1
-
-------------  sec =  kg * m / m / sec^2
-
--------------  Squaring the left side to get sec^2.    There are no kilograms on the left side of the equation , so, mass must not be a factor.  The period of a pendulum is the same regardless of the weight of the mass.  Therefore, we can guess the equation for the period of a pendulum to be:
-
--------------  ( period )^2  =  length  /  acceleration of gravity
-
---------------  T^2  =  L / g
-
--------------  sec^2  =  m / m /sec^2
-
---------------  m  =  m
-
-  And, that works.  The period is directly proportional to the length of the string.  The longer the string the longer the period.  It is inversely proportional to the acceleration of gravity.  The pendulum would have a longer period swinging on the Moon.  The period would be independent of the mass, as long as the string did not break.
-
-  The pendulum illustrates how you can solve a problem just by thinking through the dimensions involved and the units of measurement.  Now, you are ready to derive the equation for the temperature at the instant of the Big Bang:
-
-  The three fundamental dimensions are length, time and mass.  Our plan will be to use the 3 fundamental constants in Nature:  “h“, “c“, and “G“.    Use these to calculate the Energy of the Big Bang from E = mc^2.  Then use Boltzman’s Constant to convert Energy to temperature.  First let’s define the 3 fundamental constants of Nature:
-
------------  h  =  Planck’s Constant of Action.  Action is the product of Energy and Time.
-
--------------------  h  =  6.6*10^-34 kilograms * meters^2 / second
-
-------------------- h units  =  kg * m^2 / sec
-
---------------------  c  =  (speed of light)
-
---------------------  c  =  3*10^8 meters / second
-
--------------------  c units  =  (m / sec)
-
--------------------  G  =  Gravitational Constant
-
---------------------  G  =  6.7*10^-11 meters^3 / ( kilogram * seconds^2)
-
---------------------  G  units =  m^3 / ( kg*sec^2)
-
-  Using E = mc^2 all we need is Mass to calculate Energy.  We know the speed of light.  Putting Mass in terms of the units of the fundamental constants:  To get the equation to balance we need kilograms in the numerator.  One way to do that is to start with “ G” in the denominator:
-
---------------------  kilograms  =  1/ G  =  ( kg * sec^2) / m^3
-
-  Now, to cancel out sec / meter we multiply by “c” which is in m / sec:
-
------------------  kilograms  =  c / G  =  ( kg * sec^2) / m^3  * m / sec
-
-   Now, we still need to cancel more sec / meter so multiply this by:
-
-----------------  “h” which is kilograms * meters^2 / sec.
-
-----------------   kilograms  =  c * h / G  =  ( kg * sec) / m^2  *   kg  * m^2 / sec
-
----------------    kilograms  =  c * h / G  =  ( kg ^2)
-
-  Now,  we need to square the left side of the equation in order to get the equality and have all the units cancel out:
-
---------------    (kilograms)^2  =  c * h / G  =  ( kg ^2)
-
---------------  M^2  =  c * h / G
-
-  We have the Mass in terms of the fundamental constants so we can substitute the values for the constants and solve for the fundamental Mass:
-
------------ M^2  =  (3*10^8 meters / second)  *  (6.6*10^-34 kilograms * meters^2 / second)   /   (6.7*10^-11 meters^3 / ( kilogram * seconds^2))
-
----------------  M^2  =  2.955*10^-15 kg
-
-----------------  M  =  5.4 *10^-8 kg
-
-  We can calculate E = mc^2:
-
------------------  E  = (5.4 *10^-8 kg)   * ( 9 * 10^16 m^2/sec^2)
 -
------------------  E  = (50*10^8 kg * m^2/sec^2)
-
------------------  E  = (5 *10^9 Joules.
-
-  Now, using Boltzman’s constant for converting Energy to Temperature:  ( See Review # 1072 to learn about Boltzman’s Constant.)
-
---------------  T  =  (Kelvin / 1.381 *10^-23 Joules )  *  Energy
-
--------------  T  =  (Kelvin / 1.381 *10^-23 Joules )  *  (5 *10^9 Joules)
-
-----------------  T  =  3.5 * 10^32 Kelvin
-
-  Therefore the temperature at the time of the Big Bang according to the fundamental constants was 350,000,000,000,000,000,000,000,000,000,000  degrees Kelvin.  I think you needed to know that.
-
-   The same dimensional analysis method can be used to calculate fundamental time:
-
------------------  T^2 = G * h / c^5
-
------------------  T  =  1.4 * 10^-43 seconds
-
-  To calculate fundamental distance:
-
-----------------  L^2  =  G * h / c3
-
-------------------  L  =  1.62*10^-35 meters
-
-------------------------   Other Reviews that have background on this same topic:
-
-   1345  -  Absolute zero temperature strangeness.
-
-  1234  -  What happens when you cool an atom
-
-   1072  -  Boltzman’s Constant, Avogadro’s Number.
-
-    727  Absolute zero _ TEMPERATURE
-
-    406  Zero is nothing, but Absolute Zero is something else.
-
-  December 15, 2019                                                            2543       1346                                                                                   
----------------------------------------------------------------------------------------
-----  Comments appreciated and Pass it on to whomever is interested. ----
---   Some reviews are at:  --------------     http://jdetrick.blogspot.com -----
--  email feedback, corrections, request for copies or Index of all reviews
---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------
-  https://plus.google.com/u/0/  -- www.facebook.com  -- www.twitter.com
 ---------------------          Sunday, December 15, 2019    --------------------
-----------------------------------------------------------------------------------------

SUN - our closest star?

-   2542  -  SUN  -  our closest star.?   It is an average star compared with the population of stars in our Universe.  We can learn a lot about stars by studying our Sun, which is only 93,000,000 miles away.  Sun light takes just 8.3 minutes to reach us from the surface of the Sun. 
-
-

-
------------------------------------ 2542  -  SUN  -  our closest star?
-
-  This light is generated in the center of the Sun where hydrogen is fused into helium.  It is amazing that it takes 170,000 years for that light generated at the center to reach the surface , starting it’s journey to us, in just eight minutes later it is a suntan on the beach. 
-
------------------------------   distance = rate * time
-
-----------------------------   1.496 * 10^11 meters  = 2/998 * 10^8 m / sec  * time
-
-----------------------------  500 sec  = time
-
-----------------------------  8.3 minutes  =  time
-
-  The reason is, the center of the Sun is so dense due the gravitational pressure that the photons of light ricochet like billiard balls off all the other particles before they can make their way to the surface.  It takes 170,000 years to make it through this atomic maze.
-
-  A main-sequence star is one that fuses hydrogen into helium at its core. Our Sun is half way in its lifetime as a main-sequence star, 4,500,000,000 years out of 10,000,000,000 years burning hydrogen.  When the hydrogen burns out the stars die and become White Dwarfs, Neutron Stars, or Black Holes depending on the mass they begin with.  Our Sun will become a White Dwarf.
-
-  Stars vary in mass from 8% that of the Sun to 150 times that of our Sun.  Objects less than 8% the mass our Sun never begin hydrogen fusion and are technically not stars.  However, they can emit energy due to graviational pressure alone and can be seen in the infrared spectrum but not in the light spectrum.  These too-little-to-be stars are called Brown Dwarfs.  The most massive stars are 15,000% larger than our Sun.  Eta Carinae is an example of a supermassive star.
-
-  The more massive the star, the higher the gravitational pressure, the hotter the temperature, the more dense the core, and the brighter the star.  Brightness is called luminosity and there is a relationship defined between luminosity and the mass of a main-sequence star.
-
------------  Luminosity of Star / Luminosity of Sun  = ( Mass of Star / Mass of Sun )^ 3.5
-
-  Eta Carinae in the year 1841 was the second brightest object in the night sky.  That was when it went supernova.  This massive binary star survived and still holds 140 solar mass. 
-
--------------------------   Luminosity / Luminosity of the Sun  =  ( 140 / 1 ) ^ 3.5.
-
-  Luminosity is 32,500,000 times the Luminosity of the Sun, but it is 8000 light-years away. It is expected to go supernova again in 100,000,000 years, because each star is so massive.
-
-  However, the more massive and brighter the star the shorter its lifetime as a main-sequence star.  High mass stars burn up their hydrogen faster and die younger.  There is an inverse relationship between mass and main-sequence lifetime.
-
-----------  Lifetime of Star  /  Lifetime of Sun  =  ( Mass of Star  /  Mass of Sun )^ -2.5
-
-  Our Sun will live for 10,000,000,000 years.  But, if were 10 times bigger it would only be a main-sequence star for 30,000,000 years and if it were 0.1 times the mass of our Sun it’s lifetime would be 3,160,000,000,000 years.
-
-  The energy of our Sun over it’s entire live time can be calculated as:
-
-----------------------------  Energy  =   luminosity * lifetime:
-
-----------------------------  E  =  L * time
-
-----------------------------  E  =  3.9 * 10^26 watts  * 10^10 years
-
-----------------------------  L = 3.9 * 10^26 watts =  luminosity of the Sun
-
-----------------------------  Watt = joule per second
-
-----------------------------  Year = 3.17 * 10^7 seconds
-
 -----------------------------  E  = 3.8 * 10^36 * 3.17 * 10^7 joule
-
------------  E  =  12 * 10^43 joules  =  the total energy released over our Sun’s  lifetime.
-
-  Could all this energy be created by gravitational pressure or is there some other energy source in the Sun?
-
-  The energy created by gravitational collapse is proportional to the mass squared and inversely proportional to the radius:
-
-----------------------------  E  =  G  *  M ^2  / radius
-
---------------  E  =  6.67 * 10^-11 m^3/kg/sec^2  * ( 1.99*10^30 kg )^2 / 6.96 * 10^8 m
-
-----------------------------  G  = gravitational constant
-
-----------------------------  Mass of the Sun = 1.99*10^30 kg
-
-----------------------------  Radius of the Sun = 6.96 * 10^8 m
-
-----------------------------   E  =  3.8 * 10^ 41 kg * m^2 / sec^2  =  3.8 * 10^41 joules = the energy with gravitational collapse only
-
------------------------  Joule  =  work  =  force * distance  =  mass * acceleration * distance
-
-----------------------------  Joule = kg * m^2 / sec^2
-
-  Therefore, gravity alone is 1000 times too little to be the only energy source for the Sun.  There must be another source of energy.  There is and it occurs at the core of the Sun where the gravitational pressure has created temperatures of 15,000,000 degrees Kelvin.
-
-   At those temperatures, and corresponding pressures, hydrogen atoms fuse into helium, almost.  Almost, because the mass of the helium atom is a little bit less than the four hydrogen atoms combined and that little bit extra gets converted into energy according to E = m* c^2.
-
-----------------------------  The mass of four hydrogen atoms = 6.693 * 10 ^-27 kg
-
-----------------------------  The mass of one helium atom = 6.645 * 10 ^-27 kg
-
------------------------  The extra mass that is converted into energy  =  0.048 * 10^-27 kg
-
-  This mass is a small fraction, only 0.7% of the starting mass but it is enough to create enormous energy.  See footnote (2) for more details on this nuclear reaction.
-
-----------------------------    E = m * c^2
-
 -----------------------------   E = 0.048 * 10^-27 kg  *  8.99 * 10 ^16 m^2/sec^2
-
 -----------------------------   E  =  4.3 * 10 ^-12 joules.
-
-  OK, that does not look like much energy, 4.3 * 10 ^-12 joules.  But, there are 10 ^34 hydrogen atoms, or protons, interacting every second in the core of the Sun.  So, this adds up fast.
-
-  4.3 * 10^ 22 joules per second of energy from the burning of hydrogen.  Recognize that burning is a misnomer but none the less used to describe these thermonuclear reactions.
-
-   The total luminosity, or energy emitted from the Sun, is 4 * 10^26 joules per second.  This total energy emitted at the surface is a combination of nuclear fusion energy and gravitational energy. 
-
-  Our Sun burns 600,000,000 tons of hydrogen every second.  4,000,000 tons of hydrogen is converted into energy every second.  The surface of our Earth receives the equivalent of 4.5 pounds of this converted energy every second.
-
-  Larger stars have additional energy sources including helium burning, carbon burning, and iron burning to create their enormous energies.
-
-  The Sun is powered by gamma rays.  This all starts when the gravitational pressure forces two hydrogen nuclei together so close the strong force takes over and the nuclei combine.  Hydrogen nuclei are protons.  So, two protons fuse, overcoming the electromagnetic force of like polarities repelling each other, the strong fuses the protons together in a proton-proton chain reaction.
-
-   The fusion creates one proton and one neutron plus the decay products of one positron and one neutrino.  The positron and an electron annihilate each other to produce a gamma ray.  The combined proton and neutron are the nucleus of deuterium.
-
-    Next the proton and the deuterium combine to form an isotope of helium, Helium-3. Another gamma ray is released. Then the two helium-3 isotopes combine to form Helium-4 with two protons and two neutrons.  The two extra protons are released to start the next chain reaction and another gamma ray is released.
-
-   It is these gamma rays that power the Sun. The gamma rays take 170,000 years to reach the Sun’s surface.  They are colliding and interacting with millions of particles along the way.  They weaken and loose energy transforming themselves into longer wavelength electromagnetic radiation, X-rays, untraviolet rays, visible light, and infrared light. 
-
-  This transformed radiation is what eventually radiates from the surface of the Sun and what we receive here on Earth.                                                                                                                                         
-
-  December 14, 2019                                                            2542        22                                                                                     
----------------------------------------------------------------------------------------
-----  Comments appreciated and Pass it on to whomever is interested. ----
---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 
--  email feedback, corrections, request for copies or Index of all reviews
---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------
-  https://plus.google.com/u/0/  -- www.facebook.com  -- www.twitter.com
 ---------------------          Sunday, December 15, 2019    --------------------
-----------------------------------------------------------------------------------------

UNIVERSE - Structure of the universe?

-   2524  -  UNIVERSE  -  Structure of the universe?  The 2019 Noble Prize for physics went for discoveries in theoretical cosmology and exoplanets.   The farther away we look, the farther back in time we see. We will eventually reach a point where no galaxies at all have formed if we go back far enough. Understanding what our universe is made of and how it evolved to be the way it is today is an enormous existential question and worthy of a Noble Prize.
-
-

-
-------------------- 2524  -  UNIVERSE  -  Structure of the universe?
-
-  When you picture the universe, you probably start thinking of individual objects like stars and galaxies, where they’re located in space relative to one another and what those objects are doing today.  You can think about the origin and evolution and growth of everything in the universe, from the smallest cosmic scales up to the scale of the entire observable universe.
-
-  The quantum fluctuations that occur during the universe beginning with inflation get stretched across the universe, and when inflation ends, they become density fluctuations. This leads, over time, to the large-scale structure in the universe today, as well as the fluctuations in temperature observed in the CMB.
-
-  The growth of structure from these seed fluctuations, and their imprints on the power spectrum of the Universe and the CMB’s temperature differentials, can be used to determine various properties about our Universe.  The quantum fluctuations that occur during inflation get stretched across the universe.
-
-  On a logarithmic scale, the universe nearby has the solar system and our Milky Way galaxy. But far beyond are all the other galaxies in the Universe, the large-scale cosmic web, and eventually the moments immediately following the Big Bang itself.
-
-  Although we cannot observe farther than this cosmic horizon, which is presently a distance of 46.1 billion light-years away, there will be more Universe to reveal itself to us in the future. It is 46.1billion lightyears because the universe has been expanding during the time the light is traveling to each us over 13.8 billion years.
-
-  The observable Universe contains 2 trillion galaxies today, but as time goes on, more Universe will become observable to us, perhaps revealing some cosmic truths that are obscured to us today.
-
-  Some 13.8 billion years ago, the fabric of space-time was empty but full of energy inherent to space itself: a period of cosmic inflation. Then at one particular moment in time, inflation came to an end, converting that energy into matter, antimatter and radiation, and giving rise to the hot Big Bang that started it all.
-
-   Our Universe, as we know it, arose from this state, and was also born filled with dark matter, dark energy and with tiny density-and-temperature imperfections that departed from a perfectly uniform universe by about 1-part-in-30,000.
-
-  The universe ruled by the laws of quantum physics that govern matter and the gravitational force  govern the curvature and evolution of space-time expanded and cooled and gravitated, give rise to a bath of leftover radiation, a universe filled with light and heavy elements, stars, galaxies, clusters, the cosmic web and more.
-
-  Our entire cosmic history is theoretically well-understood in terms of the frameworks and rules that govern it. It’s only by observationally confirming and revealing various stages in our universe’s past that must have occurred, like when the first elements formed, when atoms became neutral, when the first stars and galaxies formed and how the Universe expanded over time, that we can truly come to understand what makes up our universe and how it expands and gravitates in a quantitative fashion.
-
-  This is the story that we know to be true today, but only the barest bones of this framework were in place back in the early 1960s when I graduated from college. Not only wasn’t inflation, dark matter or dark energy part of the story yet, but the Big Bang was only one of a few competing ideas about the universe’s origin.
-
-  We knew how successful General Relativity was, but we were still working out the details of the nuclear forces. We did not even know the particle content of our universe.
-
-   By applying the laws of physics to the system of the entire universe we began to work out details of what the universe would have been like in its early stages and how those details would evolve, over time, to produce visible signatures we could look for today.
-
-  The universe, particularly on smaller scales, is not perfectly homogeneous, but on large scales the homogeneity and isotropy is a good assumption to better than 99.99% accuracy.
-
-  The tiny, initial imperfections that the universe was born with would try to gravitationally grow from the moment they were created, but the intense radiation pressure in the early, hot, dense universe smooths out the structure on scales that are too small. Instead, particles and antiparticles collide, blasting any complex structure apart, and eventually annihilating as the universe expands and cools.
-
-  As the universe  expands and cools, more and more things become possible. Protons and neutrons can fuse into atomic nuclei, and we can use the laws of physics to calculate what the ratios of the different elements and isotopes produced should be, and then observe the universe to test it.
-
-  As the universe cools farther, neutral atoms can stably form, and all that radiation produced from annihilation should freely stream through the neutral universe, presenting an observable signature of a leftover blackbody signal just a few degrees above absolute zero.  Now called the Cosmic Microwave Background.
-
-  The relative heights and positions of these acoustic peaks, derived from the data in the Cosmic Microwave Background, are definitively consistent with a universe made of 68% dark energy, 27% dark matter and 5% normal matter.
-
-  Gravitational growth should at last occur, as matter attracts other matter and begins to collapse on all scales. As the cosmic web grows, it is counter acted by the physical effect of the expansion, and only regions that become over dense enough soon enough will eventually grow into structure.
-
-  The structures that form will be very sensitive to the contents of the universe, and how that structure clusters together on large scales can allow you to learn about what the cosmos is made of. Those signals should then also be present in the detailed fluctuations in the Cosmic Microwave Background; signals that were at last verified with satellites like COBE, WMAP and Planck.
-
-  A standard cosmic timeline of our universe’s history. Our Earth didn't come to exist until 9.2 billion years after the Big Bang, requiring many generations of stars to live and die before planets with rocky and metallic cores could exist.
-
-  Today the universe should be rich in stars with exoplanets, and they have come in forms and distributions that have forced us to reevaluate how planetary systems form and evolve.  Coming down from cosmic scales to Solar System scales, we need to go through billions of years of cosmic evolution.
-
-  Stars live and die and explode, recycling their now-fused elements into future generations of stars. When enough generations have passed, and the material found in star-forming regions is rich enough in heavy elements, stars can form with massive planets around them.
-
-  Those planets should come complete with metallic and rocky cores, just like all the planets in our Solar System. They should orbit their parent star in an ellipse, governed by the laws of gravity and having observable effects on the spectrum of the star they’re orbiting.
-
-   The gravitational planetary tug should redshift-and-blueshift the star periodically, while planets that are aligned with the star’s line of sight to Earth will transit in front of it, blocking a portion of its light.
-
-  As a planet orbits its parent star, both the star and planet will orbit in ellipses around their mutual center of mass.
-
-  Along our line of sight, the star will appear to move in an oscillatory fashion: moving towards us (and having its light blueshift) followed by it moving away from us (and seeing a corresponding redshift). This method, in 1995, yielded us the first exoplanet orbiting a Sun-like star.
-
-  Thirty years ago, only the Sun was known to have planets around it. Soon after, though, technology advanced to the point where the shift in a star’s spectral lines from “wobbling” back-and-forth would show up in long-period observations of that particular star.
-
-  While a controversial detection was first made in 1988 and the first noncontroversial detection came for planets around pulsars (a type of dead star) in 1992, neither heralded the exoplanet revolution quite like the next giant leap.
-
-  The first “normal” planet around a “normal” (Sun-like) star came in 1995.  Exoplanets became all the rage. This stellar wobble method has since been augmented by other techniques like direct imaging, microlensing and planetary transits, revealing a total of over 4,000 confirmed exoplanets so far. With TESS currently flying and additional space telescopes on the horizon, the field is richer than ever.
-
-  Today we know of over 4,000 confirmed exoplanets, with more than 2,500 of those found in the Keplerdata. These planets range in size from larger than Jupiter to smaller than Earth.
-
-  Yet because of the limitations on the size of Kepler and the duration of the mission, the majority of planets are very hot and close to their star, at small angular separations. TESS has the same issue with the first planets it’s discovering: They’re preferentially hot and in close orbits.
-
-  Only through dedicated, long-period observations (or direct imaging), will we be able to detect planets with longer period (i.e., multiyear) orbits. New and near-future observatories are on the horizon, and should reveal new worlds where right now there are only gaps.
-
-  It will take longer-duration missions with excellent light-gathering power and sensitivity to reveal the first Earth-like world around a Sun-like star. There are plans in both NASA’s and ESA’s timelines for such missions. Some of these missions, like James Webb and WFIRST, will also be extraordinary for their cosmological capabilities.
-
-  With only a small percentage of the universe and the nearest exoplanets currently revealed to us, the coming decades should see scientists in these fields push the frontiers forwards into unknown territory.
-
-  Over 90% of the 2 trillion galaxies present in our observable Universe remain undiscovered; Only 4,000 exoplanets are known in a galaxy that should contain trillions of them, including billions that may be Earth-like.
-
-  What living in these distant worlds could be human like.  Or, even life like?  Our home is so unique with so many probabilities stacking up to get to where we are.  I don’t know about you , but , being impossible makes me feel pretty important, or, more accurately just lucky.
-
-  December 4, 2019                                                                         2524                                                                                   
----------------------------------------------------------------------------------------
-----  Comments appreciated and Pass it on to whomever is interested. ----
---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 
--  email feedback, corrections, request for copies or Index of all reviews
---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------
-  https://plus.google.com/u/0/  -- www.facebook.com  -- www.twitter.com
 ---------------------          Wednesday, December 4, 2019    --------------------
-----------------------------------------------------------------------------------------

SPACETIME - Fast Speed and Short Time

-   2523  -  SPACETIME  -  Fast Speed and Short Time.  You should be fascinated by time and space.  Both seem so fundamental, yet, Einstein’s Theory of relativity proves that time and space are not absolutes.  They are relative.  They are one thing, not two things, spacetime is one thing.  Space and Time bend and curve when they interact with mass.  Mass tells spacetime how to bend and spacetime tells mass how to move.
-
-

-
-------------------- 2523  -  SPACETIME  -  Fast Speed and Short Time
-
-   Space and Time bend and curve when they interact with mass.  Mass tells spacetime how to bend and spacetime tells mass how to move.
-
-  The ratio of space over time is the speed of motion.  And, it appears that everything in the Universe is moving with some velocity.  We measure time with the Earth’s rotation.  Earth takes one rotation on its axis every 86,400 seconds.  On the surface of Earth your speed of rotation depends upon your latitude.  At the equator it is moving at 1,040 miles per hour.
-
-  In Santa Rosa, California, at 38 degrees, 20 minutes, 12 seconds latitude, 174 feet elevation we are traveling at 645.1 miles per hour.  If you are walking east at 4 miles per hour  with Earth’s rotation you are moving at 649 miles per hour.  If you are driving home to Santa Rosa coming from the ocean, at 65mph you are moving at 710 miles per hour.
-
-   If you are in a plane flying home from Japan you are moving 1,245 miles per hour but the air around the plane is traveling at the same speed as the Earth which is 645 miles per hour.  The plane is traveling 600 mph relative to the air and the ground.
-
-  Let’s compare the planets that have a rotational speed about their axis, measured at the equator, and an orbital speed about the Sun, all in miles per hour.
-
------------------  Planet  -------------------  Rotational  -------------------  Orbital
-
------------------  Mercury  -------------------  6.8  -------------------------  107,098
------------------  Venus  ----------------------  4.1  --------------------------  78,341
------------------  Earth  ----------------------  1040  -------------------------  66,629
------------------  Mars  -----------------------  539 ---------------------------  53,979
------------------  Jupiter  -------------------  28,361  -------------------------  29,236
------------------  Saturn --------------------  22,994---------------------------  21,614
------------------  Uranus ---------------------  5,788  -------------------------  15,290
------------------  Neptune --------------------  6,001  -------------------------  12,253
------------------  Pluto  -----------------------  30.4  ---------------------------  10,620
-
Halley’s comet when closest to the Sun is traveling at 12,070 miles per hour.  When farthest from the Sun,  2,039 miles per hour.  The Sun is rotating at 2,231 miles per  hour and orbiting the center of the Milky Way Galaxy.
-
------------------  Sun -------------------------  2,231  -------------------------  486,000
-
-  Note that the planets are going slower the farther they are from the Sun.  This is the result of the law of conversation of angular momentum.  Momentum is mass times velocity.  p = m*v.  Planets have elliptical orbits and they travel faster when closer to the Sun and slower when farther away because angular velocity is measured in tangential speed times the radius.
-
-  The planets distance from the Sun is the radius.  These tangential orbital velocities are the averages between the maximum and minimum radii.  Rotational speeds are given for surface at the plant’s equator, which is also a tangential velocity. 
-
-  The Andromeda Galaxy (M31) is speeding towards the center of the Milky Way galaxy at 220,000 miles per hour.  Because our Solar System’s orbit is today is going towards M31 we happen to be approaching Andromeda at 676,000  miles per hour.
-
-  Our Local Group of 36 galaxies, the Milky Way and Andromeda being the biggest, is speeding toward the Great Attractor in the Virgo Cluster of Galaxies.  One of the galaxies representing an average, M84, is receding at 2,370,000 miles per hour.  M84 is 50,000,000 lightyears away.
-
-  The Coma Custer of Galaxies which is 350,000,000 lightyears away contains 10,000 galaxies that are receding at 16,000,000 miles per hour.  The Universe is expanding.  So what gets complicated is that the galaxies are not traveling at 16 million miles per hour by themselves.  It is the space between us and the galaxies that is expanding to cause our separation to be expanding at 16 million miles per hour.
-
-  The Cosmic Microwave Background radiation, which is the most distant radiation we can observe, is 13,700,000,000 lightyears away.  It is receding away from us at nearly the speed of light.  Light radiation is the fastest velocity known.  It speeds around your backyard and from as far away as the farthest galaxy at 670,615,200 miles per hour.  This is 186,282 miles per second.

-  The human heart beats once per second,  lightning strikes in 1/100th of a second, 10^-2 seconds.  In everyday photography a camera can stop time at about 1/1000th of a second, 10^-3 seconds.  Computers work at clock speed of 10^-9 seconds, a billionth of a second. 
-
-  Circuits have electrical switches that can operate at 10^-12 seconds, a trillionth of a second.  Scientists today are working with laser pulses that can stop time at 650 *10^-18 seconds, 650 attoseconds.

-  About 20 years ago lasers could create a pulse of 6 femtoseconds, 6*10^-15 seconds.  If one femtosecond is to 90 seconds, then 90 seconds is to the age of the Universe, 13,700,000,000 years. Chemical bonds break and reform in molecules in about 100 to 200 femtoseconds, 200*10^-18 seconds.

-  Two years ago lasers could create a pulse that was 650 attoseconds long, 650 *10^-18 seconds.  The is fast enough to stop the motion of an electron in an atom.  In nuclear physics the natural timescales inside an atom are in the order of zeptoseconds, 10^-21 seconds. 
-
-  We have yet to invent this laser that can stop the motions inside the nucleus of an atom.  We working on it.
-
-------------------------  deci  ------------  10^-1
-------------------------  centi  ------------  10^-2
-------------------------  milli  ------------  10^-3
-------------------------  micro  -----------  10^-6
-------------------------  nano  ------------  10^-9
-------------------------  pico  ------------  10^-12
-------------------------  femto  ----------  10^-15
-------------------------  atto  ------------  10^-18
-------------------------  zepto  ----------  10^-21
-------------------------  yocto ----------  10^-24
-
-  Attoseconds and zeptoseconds seem incomprehensible,  how can one even imagine these timescales?
-
-  Ok, let’s say you have a really, really fast motorcycle that would travel from Los Angeles to New York in one nanosecond, 10^-9 seconds to travel 2,787 miles.  In one picosecond, 10^-12 seconds, the fast motorcycle would have only traveled 2.8 miles, barely getting to East L.A.  In one femtosecond, 10^-15 seconds, it would have traveled about 1/5th of an inch.
-
-  If you held on and your motorcycle really went that fast, in one second it would have passed New York , went into orbit and circled the Earth 112,000,000 times, in one second.  How time flies.
-
-  If you were in a race with your motorcycle and you won by a single attosecond (10^-18 seconds) you would have won  the race by less than the width of an atom, in fact, in less that the width of a proton.  If you were second place your time would have been the same as the first place motorcycle plus 0.000,000,000,000,000,001 seconds.  That was close.
-
-  The smallest fraction of time is thought to be 10^-43 seconds.  It is called a Planck second.  That happens to be the time it takes light the fastest thing possible to travel the smallest distance of space 10^-35 meters, called the Planck Length.
-
-  The reason this is the smallest unit of length is that if it got any smaller it would become a Black Hole.  See Reviews 724 and 734 for the details.  The last thing we want to be is near a Black Hole.  Or, maybe we are inside one now and the edge of the Black Hole is the edge of the Observable Universe.  Nothing even light can escape from the Observable Universe, or, if it can we can’t see it. 
-
-  So, maybe from the outside looking in the Universe is a Black Hole.  The Observable Universe is 1.3*10^26 meters.  When you go backwards in time and reduce that to 10^-35 meters you enter another Black Hole.
-
-  What do you suppose happens to space and time inside a Black Hole?  We have more to learn.
-
-  For more info  see Reviews:
-
-  1242  -  How does spacetime change at the micro level?
-
-  2271  -  Hw can space and time be related?  Also lists 13 more reviews about spacetime.
-
-  2213  -  Spacetime from atoms to blackholes.
-
-  2180  -  Velocity is space divide by time.
-
-  1790  -  Space bends and time slows.
-
-  2522  -  Space - curved or flat?  Also, lists 14 more reviews about space.
-
-  December 4, 2019                                                   2523    2001        814                                                                                     
----------------------------------------------------------------------------------------
-----  Comments appreciated and Pass it on to whomever is interested. ----
---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 
--  email feedback, corrections, request for copies or Index of all reviews
---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------
-  https://plus.google.com/u/0/  -- www.facebook.com  -- www.twitter.com
 ---------------------          Wednesday, December 4, 2019    --------------------
-----------------------------------------------------------------------------------------

SPACE - curved or flat?

-   2522  -  SPACE  -  curved or flat?    The concept of curved space and time is challenging.  Most of the concept relies on mathematics to provide the descriptions, but, math is another language that has to be learned first.  It is impossible to leave space.  It holds everything.  Like time keeps everything from happening all at once, space keeps everything from being in the same place.
-
-

-
-------------------- 2522  -  SPACE  -  curved or flat?
-
- The shape of the universe is one of the most important questions in cosmology, with far-reaching implications, up to and including the ultimate fate of the cosmos.
-
-  For decades, we've been measuring our universe to be geometrically flat, but a team of cosmologists are now reporting that our latest measurements actually prefer something rounder.
-
-  The surface of the Earth is curved. We know this because the tiles of geometry that you learned in high school don't always apply. For example, parallel lines don't always stay parallel on the Earth: lines of longitude intersect at the north and south poles, something that can never happen on a flat plain.
-
-  If you were to draw a triangle connecting three cities on the Earth, you would find that the angles inside that triangle add up to more than 180 degrees.
-
-  Astronomers are very curious about the ultimate curvature of the universe: how do parallel lines and triangles behave on the very largest scales? They care because the shape of the universe is intimately connected to its fate. Einstein's theory of general relativity, which we use to understand the cosmos, tells us that the contents of space-time affect its shape, and the shape tells the contents how to move.
-
-  A geometrically flat universe will just keep on expanding forever, while a "closed" one will eventually pull back in on itself, leading to the reverse of the Big Bang, something called the Big Crunch.
-
-  To test the geometry of space-time, we need to look at all sorts of distant sources and determine if the light from those sources has undergone any major deviations in its path to us. Light beams should stay on the straight and narrow over billions of years, so we can use distant probes to "smooth over" tiny little bumps and wiggles like those caused by galaxies and black holes, and look at the true, underlying geometry of the universe.
-
-  The cosmic microwave background (CMB) is a bath of light soaking the universe, left over from when our cosmos was just a baby, only 380,000 years old. That light has spent the past 13.8 billion years racing to us, so we can study features in the CMB to test our universe for flatness.
-
-  The Planck satellite was the latest effort to map the CMB across the whole sky. Planck did a really good job, measuring the CMB to the greatest level of precision yet, with its most recent data released in 2018.
-
-  If you look at the bare, raw, naked data of the CMB as recorded by Planck, it seems that our universe might just prefer to be closed. The measurement isn't significant enough to be considered ironclad, but it's still suggestive. This is intriguing because everything we know through our theory of the Big Bang suggests that instead our universe should be very, very flat.
-
-  Taking the Planck data hinting at a curved universe in isolation, we have two possible options:
-
------------------  (1)   Planck is telling the truth, and the universe just might be curved.
-
------------------ (2)  Planck is lying to us, and either something in the instrument itself or some other astronomical source (for example, pesky interstellar dust) is making the universe look curved when it really is flat.
-
-  The Planck Collaboration itself did a lot of analysis and checking, and came to the conclusion that our universe is really flat, but that some other contaminant is nudging the data to make it look curved.
-
-  But more recently, a trio of astronomers performed their own analysis and came to the opposite conclusion: Planck is not a liar, and the universe is indeed curved.
-
-  Ask any detective, and they'll tell you that eyewitness testimony is always shaky. You need multiple, unconnected people giving similar accounts of an incident before you can paint a reliable portrait. And so to determine if Planck is lying to us or not, we need to ask some other eyewitnesses.
-
-  Thankfully, cosmologists have a lot to draw from, with measures aplenty that inform us about the curvature of the universe.
-
-  The Planck team took a straightforward approach. The researchers combined the data from the Planck satellite with data from other observations, mixed them all together (in a statistically appropriate way) and asked the combined data set about the curvature of the universe. The answer? No curvature at all.  Therefore  we live in a flat cosmos.
-
-  In 2019 according to Planck team members, their own data aren't perfect trustworthy when it comes to curvature, and the measurements of the CMB have to be combined with other cosmological probes to get an accurate answer.
- 
-  So is Planck lying to us or not? The Planck Collaboration says yes; the trio of astronomers (who also happen to be members of the Planck Collaboration) say no. While a curved universe seems very unlikely, only more data and more digging in will settle the controversy
-
-   How can space be curved?  2,200 years ago curvature was determined by plane geometry.  Relativity showed us space was curved by mass and gravity.  Today curvature in space tells us 96% is mysterious Dark Mass and Dark Energy.
-
-  The concept of curved space and time is challenging.  Not easily digested.  Most of the concept relies on mathematics to provide the descriptions, but, math is another language that has to be learned first.
-
-  And, even space itself is a hard concept.  It is impossible to leave space.  It holds everything.  Like time keeps everything from happening all at once, space keeps everything from being in the same place.
-
-   If we study space we have to study it from the inside.  A corollary might be how early humans discovered that the Earth was not flat, it was not seen as a giant sphere  not totally visible until thousands of years later.
-
-  Math was used by an Egyptian, Eratosthenes, 2,200 years ago to show the Earth was a sphere and we could calculate its circumference.  He used plane geometry.  He used camel drives to gage the distance between two cities, Syene and Alexandria.
-
-   He assumed the Sun’s rays were parallel lines.  At noon in Syene he saw the Sun light directly overhead  reach the bottom of a well.  At noon in Alexandria, 5,000 stadice away, the Sun rays were at an angle of 1/50 of a circle ( 7 degrees, 12 arc-seconds)  A full circle would be 50 * 5,000 stadice, or 35,000 miles for the circumference.  The Earth is 24,901 miles circumference.  He was 29% to high.  The camels must have been taking shorter steps that day. 
-
-  Using geometry on curved surfaces did not arrive until 1818 when Carl Gauss showed that for curved surfaces the laws of geometry were different.  The shortest distance between two points is not a direct line.  The shortest path is always a geodesic, a curved arc with the center at the center of the Earth in the case of our sphere.
-
- Euclid decided that not only the Earth’s surface was curved, but, space itself was curved.  The tracers for the geodesics are rays of light.  Light always takes the shortest path in empty space.  Gravitational lensing uses the fact that light bends passing through curved space created by a massive object.
-
-  It was not until 1916 that the General Theory of Relativity showed us the math for curved space.  Space curves in response to mass.  Arthur Eddington first demonstrated how star light bends around a solar eclipse.
-
-  So, if we can measure how much mass bends light we can calculate how much mass is there.  The biggest effect occurs around galaxy clusters, the most massive objects in the Universe.  Clusters contain thousands of galaxies and billions of stars.
-
-  The surprising result measuring bending starlight ( actually quasars) was that cluster contain more mass than can be seen.  This missing mass is known as Dark Matter and we have yet to discover what it actually is.  It is affected by gravity but not electromagnetism.
-
-  Astronomers are using this technique on the Cosmic Microwave Background radiation, light that has been redshifted into the microwave spectrum after 13 billion lightyears traveling through expanding space.  The “ hotspots” in the fabric of the CMB are magnified or shrink from actual size.  If we can determine the true size we can calculate the magnification and the average curvature of space.
-
-  The result:  On average the curvature of space is flat.  And, the density of mass is on average 10^-29 grams per cubic centimeter.  With that small a number it is obvious the most of space of “empty” of mass.  But, add up all the mass in the Universe and it reaches only 30% of the calculated result using this density.
-
-  Where is the missing 70% of the universe?  It has been given the name “ Dark Energy”.  Remember, energy and mass are the same thing.  Mass is concentrated energy according to E=mc^2.
-
-  What we model as “ space” today is resembling and old picnic table.  Full of chips and scratches you can see up close.  But, from a distance the table top looks perfectly smooth and flat.  The chips and scratches correspond to small regions of strong space curvature due to the gravity from individual stars and galaxies.
-
-  These stars and galaxies account for only 4% of the mass-energy in the Universe.  The other 96% is the missing matter and energy.
-
-  We have come a long way from plane geometry in understanding the Universe.  With 96% left we have a long way to go.
-
-  Maybe the Universe appears flat because it is so big even if it is curved we can not ever be able to notice it.
-
-------------------------  Other Reviews available about space:
-
-  2475  -  space is not nothing
-
-  2404  -  the vacuum of space.   Also lists 8 more Reviews about space.
-
-  2279  -  inventions for earthlings.
-
-  2252  -  what did we learn in space?
-
-  2243  -  what is space really?   Also lists 5 more Reviews about space.
-
-  2074  -  much todo about nothing.
-
-  2049  -  the expanding space.
-
- 2029  -  dust is outer space.  Lists 11 more Reviews about space.
-
-  1986  -  space is what separates things.  Time is what keeps everything from happening all at once.
-
-  1831  -  from Blackholes to empty space.
-
-  1790  -  why space ant time must change as we approach the speed of light.
-
-  1773  -  the size of space depends on how fast you are moving.
-
-  1407  -  space is in constant motion.-
-
-  1241  -  At the smallest levels things remain connected.  Even though they are separated in space.
-
-  December 3, 2019                                                      2522          1861                                                                         
----------------------------------------------------------------------------------------
-----  Comments appreciated and Pass it on to whomever is interested. ----
---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 
--  email feedback, corrections, request for copies or Index of all reviews
---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------
-  https://plus.google.com/u/0/  -- www.facebook.com  -- www.twitter.com
 ---------------------          Tuesday, December 3, 2019    --------------------
-----------------------------------------------------------------------------------------

CELLS - You Are As Young As You Feel?

-   2521  -  CELLS  -  You Are As Young As You Feel?  None of us have bodies that are over 9 years old.  Really, that’s true!  And, the entire surface area of our bodies are already dead.  Here are some interesting things to know about the cells in your body.
-
-

-
-------------------- 2521  -  CELLS  -  You Are As Young As You Feel?
- 
-  Hard to believe, but, every molecule in your body has been replaced at least 9 years ago.  None of your parts at the molecular level are more than 9 years old.  The cells in your body are constantly replacing themselves.
-
-  All the cells on the surface area of your skin are already dead.  You have probably 5 pounds of dead skin that your are carrying around.  But, don’t try to shed it just to loose weight.  It sheds itself in the form of that gray dust you see on your coffee table.  That dust is largely old skin.  The same as that gray stuff on the inside of your vacuum cleaner.
-
-  Most living cells in our body live an average of one month.  Liver cells survive for years although the parts inside the cells are renewed every few days.  You get 100,000,000,000 brain cells at birth.  And, that is all you get.  And, you are loosing 500 brain cells an hour your whole life.  I better hurry up and finish this review.   I do not have many brain cells left.  79*365*24*500 =  346,620,000 brain cells are already gone.
-
-  The cell membrane, in effect the skin of the cell, is really only a fatty material called a “lipid“.  It is about the consistency of a light grade motor oil.  Remember ,we are talking about the nanometer scale and things are different with things are this small.  Liquid water becomes a heavy-duty gel.  Lipids are like an iron shell.
-
-  If you could blow up a human cell so that atoms were the size of peas the entire cell would be a half mile across.  Inside the cell would be like meteor storm with basketball-size and car-size objects flying around constantly in all directions. 
-
-   An atom is 10^-10 meters across.  A pea is 10^-2 meters across.  So, everything is magnified by 10^8 times, or 100,000,000 larger on this scale.
-
-   Each strand of your cell’s DNA gets damaged every 8.4 seconds, on average.  That works out to be 10,000 times per day that your cell’s DNA has to repair itself, or it dies. 
-
-  Remember, the cell, or the parts of the cell, only live for about a month on average.  Some protein molecules only live for 30 minutes before they die.  Other protein molecules will live for several weeks.
-
-  What powers all this activity in a living cell?  Every cell is full of electricity, about 0.1 volts across a nanometer.  A human cell is 10^-5 meters across, that is 10,000 nanometers across.  0.1 volts is not much electricity.  You certainly do not feel it. 
-
-  But, if you scaled it up to a meter it would be equivalent to a thunderstorm lightning bolt of 20,000,000 volts per meter.  The cell’s battery packs that carry this electricity will be explained later:
-
-  Inside the human cell is a dynamic activity that is happening at speeds you can not imagine.  It is all controlled by communications between different types of molecules:  Inside each cell there are millions of these objects:

-------------------  lysosmes
-
-------------------  endosomes
-
-------------------  ribosomes
-
-------------------  ligands
-
-------------------  peroxsomes
-
-------------------  proteins, 20,000 different types
-
------------------  each protein with 50,000 molecules.
-
-  To stay alive each cell in your body must receive its own blood supply  Small blood capillaries reach every living cell.  To get the blood through this vast network of vessels the heart must pump 75 gallons of blood every hour.
-
-   That is 1,800 gallons of blood moving inside your body every day.  That is the size of a small swimming pool.  And, this activity only applies when you are resting.  Start vigorous exercise and all this increases up to 6 fold.
-
-  Each cell collects oxygen from the blood using mitochondria.  The origin of mitochondria  is likely captured bacteria that have learned to live inside a cell.  The cell gets the benefit because the mitochondria convert oxygen energy into adenosine triphosphate which are the battery packs that power the cell.
-
-  Every 2 minutes the adenosine triphosphate battery packs dump all their electricity and go dead.  They are replace by 1,000,000,000 of them coming on line and this happens every 2 minutes.  If you skin feels warm that is adenosine triphosphate your cells are producing that is equal to half your body weight.
-
-  Every day 1,000,000,000’s of cells die and the other cells clean up the mess.  If a cell does not die when it is supposed to, but, instead, starts to grow and divide, that is cancer.
-
-  Hormones are the communication carriers that tell cells what to do.  Hormones include:
-
-------------------  insulin
-
------------------  adrenaline
-
------------------  estrogen
-
------------------- testosterone
-
-  Brain cells communicate through the nerve cells. Cells also have the capability to communicate with each other.  Neighbors cooperate to work on a coordinated effort.
-
-  Somehow all this results in a walking, talking, thinking you.  Atomic engineering at its finest.  The common ingredient appears to be a focused quest for survival. 
-
- Sorry, I need to end this Review.  I have already burned up to many brain cells.  And, by last count I do not have many more left. Only, 99,653,380,000 brain cells left to work with.
 -
-  December 3, 2019                                                  2521            1299                                                                                     
----------------------------------------------------------------------------------------
-----  Comments appreciated and Pass it on to whomever is interested. ----
---   Some reviews are at:  --------------     http://jdetrick.blogspot.com ----- 
--  email feedback, corrections, request for copies or Index of all reviews
---  to:  ------    jamesdetrick@comcast.net  ------  “Jim Detrick”  -----------
-  https://plus.google.com/u/0/  -- www.facebook.com  -- www.twitter.com
 ---------------------          Tuesday, December 3, 2019    --------------------
-----------------------------------------------------------------------------------------