------
-
- The Hubble Constant is a calculation for the rate at which the Universe is expanding. Astronomers could see that the further a galaxy was away from us the faster it was receding. However, the ratio of the two was a Constant. If the galaxy was 1 million lightyears away it was going 47,000 miles per hour. If it were 10 million lightyears away it was going 470,000 miles per hour. And so on:
-
- To get the distance to the galaxy astronomers used Cepheid Variable stars that have an intrinsic brightness. The dimmer the star the farther away it was. Brightness falls off as the square of the distance.
-
- To get the receding velocity astronomers used the Redshift of the light spectrum. The faster the receding velocity the more the wavelength of the light was stretched, the longer the wavelength the redder the color of the light being received.
-
- Hubble’s Constant is the ratio of the galaxy recession speed by its distance. The early calculations ranged from 50 kilometers per second per mega parsec to 80 km/sec/mpc. A mega parsec is 3.26 million lightyears distance. Today the calculation is :
-
------------------ 72.4 km/sec/mpc, or
-
------------------ 47,000 miles per hour per million lightyears.
-
------------------ Velocity = ( Hubble Constant ) * distance
-
----------------- Distance = velocity * time
-
----------------- Time = 1 / ( Hubble Constant )
-
------------------ Age of the Universe = 1 / ( 47,000 m ph / million LY )
-
------------------ Age of the Universe = 13.7 billion years.
-
----------------- Age of the oldest rocks on Earth = 3.8 billion years ( 28%)
-
---------------- Age of the oldest meteorites = 4.6 billion years ( 34% )
-
---------------- Age of the Milky Way disk = 10 billion years ( 73% )
-
--------------- Age of the Cosmic Microwave Background radiation = 13.7 billion years
accurate to within 1% error.
-
- So, if the Universe has been expanding for 13.7 billion years how big is it today?
-
- A high value for the Hubble Constant ( 80 ) meant a younger age and a smaller size ( 10 billion LY). A low value for the Hubble Constant ( 50 ) meant the Universe was older and larger ( 16 billion LY )
-
- With the most powerful telescopes astronomers can see galaxies that are 12 billion lightyears away. ( One lightyear is 6 trillion miles distance ).
-
- Astronomers looking 12 billion lightyears over our eastern horizon and 12 billion lightyears over the other western horizon are viewing galaxies that are similar yet 24 billion lightyears apart.
-
- How could both locations in the sky be the same when light has not had time to reach between them? In order to be the same the two regions in the sky must have been close together sometime in the past.
-
- This dilemma was solved with the theory of Cosmic Inflation. Shortly after the Big Bang the Universe expanded faster than the speed of light. The Universe near instantaneously went from sub-atomic size to the size of a softball. ( From 10^-27 centimeters to 10 centimeters ).
-
- This theory would mean that the Real Universe is much bigger than the Observable Universe, 10^50 times bigger than the Observable Universe which has a radius of 13.7 billion lightyears.
-
- When the expansion started matter, energy, space and time were all together in an infinitely dense and hot plasma. As expansion occurred things got less dense and cooler.
-
- For the first 10^-43 seconds matter, energy and the 4 forces were all the same.
-
- When the expansion reached 10^-35 seconds Cosmic Inflation occurred and the Universe expanded by a factor or 10^50 in only 10^-33 seconds. After 10^-2 seconds the expansion slowed down to near its current rate of expansion. ( according to the Grand Unification Theory.)
-
- With expansion and cooling matter formed, Neutrinos, electrons, quarks and photons. Then, protons and neutrons. Particles and antiparticles annihilated each other producing Gamma Rays. Somehow, rather than equal annihilation matter came out in excess. We can’t explain how this happened but lucky for us it did.
-
- One second after the Big Bang atoms formed into hydrogen, helium, and lithium elements. With matter came gravity and over the next 10,000 years the irregularities of matter density expanded into the structures of a web of galaxies.
-
- 380,000 years after the Big Bang the opaque Universe of charged particles became dominated by neutral atoms and the Universe became transparent for light to escape. Matter and radiation separated.
-
- We see that radiation today as Cosmic Microwave Background radiation. It started out as Gamma Rays but over the 13.7 billion years of expansion the Gamma Ray wavelengths have been stretched to microwave wavelengths.
-
- Dark Matter was first proposed to exist in 1930 to explain why spinning galaxies do not fly apart. Extra mass was needed to hold the rotating galaxies together. Later this proposal was reinforced with data that stars orbiting far from the center were not orbiting slower. Unlike our Solar System where planets far from the Sun ( Saturn ) have slower orbital velocity that those closer to the Sun ( Mercury ). Therefore keeping their angular momentum a constant conservation of energy.
-
--------------------- Mercury, 57.9 million kilometers orbit has orbital speed of 105,136 miles per hour.
-
------------------- Saturn, 1,427 million kilometers orbit has orbital speed of 22,369 miles per hour.
-
- In order to explain why orbiting stars near the center of the galaxies have the same orbital velocity as those far away form the center there must be a massive spherical halo of mass ( Dark Matter ) surrounding the visible galaxy disk. The same analysis repeats with orbiting galaxies in clusters of galaxies. ( See Review on Dark Matter to learn possible forms of matter interacting with gravity and not with electromagnetic radiation (light )).
-
- Astronomers have studied 72 galactic clusters. When galaxies collide stars and gas interact differently than Dark Matter during the collision. The gas slows down due to friction and electromagnetic interactions, but the Dark matter flies through the collision with no interactions. Dark Matter appears to not even interact with itself.
-
- Each galaxy collision takes 100’s of millions of years, therefore, many collisions have to be studied to get an idea how collisions evolve over time. Each observation is but one frame in a movie.
-
- Conclusions are that the Dark Matter does not experience the frictional forces during these collisions. Indirect evidence with Dark Matter’s interaction with gravity is our only evidence we have so far.
-
- An even bigger mystery surrounds explaining why the Universe is expanding at an accelerating rate. It is called the result of Dark Energy, but, that is just a name without an explanation.
-
- If you are interested in studying astronomy it is nice to know that 95% of the Universe is left for your exploration. Everything else in this review was what we learned about the other 5%.
-----------------------------------------------------------------------------------------
----------------- RSVP, Pass it on to whomever is interested. ----------------
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email comments, 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
----- 707-536-3272 ---------------------- Thursday, April 2, 2015 -----
------------------------------------------------------------------------------------------
No comments:
Post a Comment