Expansion of The Universe

Oct 21, 2019
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I have been into the whole space scene for about 2 years now! It’s amazing to learn something new everyday in this community but here’s a question that may be a dumb one lol. When we say the universe is expanding are we saying just the trillions of galaxies are getting further apart or are is it expanding as in more and more galaxies are being formed in the universe?
 

rod

Oct 22, 2019
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Tyler.k2, my understanding (I am an amateur astronomy buff and observer) is there are no new galaxies forming in the Big Bang model. 3-D space continues to expand and calculated based upon the Hubble constant that computes the Hubble time. Folks may enjoy using these cosmology calculators I found on the web - https://ned.ipac.caltech.edu/help/cosmology_calc.html. Redshift numbers for galaxies like z=1 or 2 or perhaps 3, is converted into light-years distance but those targets no longer exist at those distances from Earth - moved way beyond where telescopes can see today - limited by the cosmic microwave background, according to the cosmology calculators :) According to the Big Bang model, the universe expanded from an area smaller than an electron :)
 
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rod

Oct 22, 2019
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tyler.k2, asked "When we say the universe is expanding are we saying just the trillions of galaxies are getting further apart or are is it expanding as in more and more galaxies are being formed in the universe?" My answer is that space is expanding and the galaxies are being carried along for the ride in the Big Bang model and no more galaxies forming. In the Big Bang model, at the moment of the Big Bang, 3-D space is created instantaneously everywhere, so 3-D space just continues to expand. I know using my telescopes as an amateur, I do not see redshifts emerging from an area smaller than an electron :) Many targets with large z numbers today are far beyond the CMBR we see it seems and not visible today in the Big Bang model.
 
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Oct 23, 2019
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You can do a simple experiment with a rubberband that will nicely illustrate what is meant when it is said that the universe is expanding.

1. Take a rubberband and cut it so you can lay it out flat on a table.
2. Now take a sharpie and place a series of dots along the rubber strip.
The rubberband represents space itself.
The dots you put on it represents galaxies.
3. Take each end of the rubber strip and stretch it and watch what happens.
 
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rod

Oct 22, 2019
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EjmMissouri - very nice. The expanding universe depends upon the Hubble constant - more reports appearing that H0 may be having a fit :) "A crisis in cosmology: New data suggests the universe expanding more rapidly than believed", ref -https://phys.org/news/2019-10-crisis-cosmology-universe-rapidly-believed.html. Some claims for H0 now suggest a universe about 11.5 billion years old, according to the Big Bang model interpretation. H0 has not behaved well over the years folks, at least past report suggest this to me :)

From some notes I keep in my home database - [The Hubble time measures the age of the universe since the Big Bang, using the Hubble constant. The larger the Hubble constant, the less time that elapsed since the Big Bang and the younger the universe must be. How old is the universe according to the Hubble constant?

Quick history: (A.) Edwin Hubble is credited with discovering the expanding universe from galaxy red shifts in the 1920s. The result was the Hubble constant which attempts to measure the rate of expansion of the universe.
(B.) In the 1930s, the Hubble constant pointed to a universe that started its expansion about 1E+9 years ago. This contradicted what astronomy was teaching about "the development of individual stars and systems of stars takes considerably longer. It is in no way known how this incongruity is to be overcome." Ref: Relativity, The Special and The General Theory, Albert Einstein, Crown Publishers Inc., 1961, p. 134.
(C.) In the 1940s and early '50s, not much better, about 1.8E+9 years old universe. Problem with this situation was that radiometric dated rocks were at least 3 billion years old and in 1955, the age of the earth was established at 4.56 billion years old. An error was discovered in measuring galaxy distances based upon Cepheid variables (galaxies much farther away than had been thought). The age of the universe increased to at least 5E+9 years old. Ref: "The Evolutionary Universe" by George Gamow, Scientific American, September 1956. Reprinted in New Frontiers in Astronomy, W.H.Freeman and Company, 1975, p. 320.
(D.) Today the Hubble constant points to a universe in the range of 8E+9 <= universe age <= 16E+9 years old. This would be the Hubble time. Based upon my readings, the most popular value for the Hubble time is 13.7/13.8E+9 years old according to publications today. The age of the Milky Way galaxy is 10E+9 <= age <=11E+9 years old.]
 
Oct 23, 2019
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I have been into the whole space scene for about 2 years now! It’s amazing to learn something new everyday in this community but here’s a question that may be a dumb one lol. When we say the universe is expanding are we saying just the trillions of galaxies are getting further apart or are is it expanding as in more and more galaxies are being formed in the universe?

I think the answer to your question might be in this great article from Ethan Siegel, contributor to " Starts with a bang " web site.

 

rod

Oct 22, 2019
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Yes folks, H0 is what I call a miscreant constant :) Here is a new report on H0, Scientists further refine how quickly the universe is expanding I note some comments from the report, "Hubble originally estimated the expansion rate to be 500 kilometers per second per megaparsec, with a megaparsec being equivalent to about 3.26 million light years. Hubble concluded that a galaxy two megaparsecs away from our galaxy was receding twice as fast as a galaxy only one megaparsec away. This estimate became known as the Hubble Constant, which proved for the first time that the universe was expanding. Astronomers have been recalibrating it—with mixed results—ever since. With the help of skyrocketing technologies, astronomers came up with measurements that differed significantly from Hubble's original calculations—slowing the expansion rate down to between 50 and 100 kilometers per second per megaparsec. And in the past decade, ultra-sophisticated instruments, such as the Planck satellite, have increased the precision of Hubble's original measurements in relatively dramatic fashion."

Using H0 = 500, I can get a universe 1.591 billion years old using the open model. The flat model shows 1.911 billion years old. However this report suggests 67.5 now. "This novel strategy led to a measurement of approximately 67.5 kilometers per second per megaparsec."

So using the cosmology calculators, I get a universe 11.781 billion years old using the open model. The flat model provides 14.147 billion years old.

https://ned.ipac.caltech.edu/help/cosmology_calc.html

This is fun 😊
 
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Nov 25, 2019
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I have been into the whole space scene for about 2 years now! It’s amazing to learn something new everyday in this community but here’s a question that may be a dumb one lol. When we say the universe is expanding are we saying just the trillions of galaxies are getting further apart or are is it expanding as in more and more galaxies are being formed in the universe?
I think it's both because with it expanding farther apart there's room for new developments to happen in the empty space. I don't believe it will ever stop expanding because new things always have to develop. it fits done expanding its going to collide with another universe that were unaware of
 
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Jan 9, 2020
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I have been into the whole space scene for about 2 years now! It’s amazing to learn something new everyday in this community but here’s a question that may be a dumb one lol. When we say the universe is expanding are we saying just the trillions of galaxies are getting further apart or are is it expanding as in more and more galaxies are being formed in the universe?
 
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Reactions: rod
Jan 9, 2020
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What it means is that the fabric of space is expanding. Individual stars contract & expand depending on their metabolic processes. Galaxies can collide because they are moving thru space & attracted by gravity. Inside a galaxy, there may or may not be new stellar nurseries-depends on the type of galaxy or cluster. E.g. the Magellanic Clouds (only visible in the South Hemisphere) is a stellar nursery. This is the Eagle Nebula region. Dense globular clusters are very old & not into star-formation. Stellar birth tends to happen on the arms of spirals. Also anytime stars go kaput, it just provides material to be gobbled up by some other region to begin a new star. All interstellar stuff moves in space. And all is held by even the slightest of gravitational attractions. What is meant by the fabric of space expanding is the stuff in between is getting larger between objects. Picture this experiment place some objects on a tablecloth in turn on a table. Have 2 people at each end try to lift the cloth & one will see how the objects orient themselves.
 
Jan 7, 2020
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Cosmological constant abandoned
Main article: Cosmological constant
After Hubble's discovery was published, Albert Einstein abandoned his work on the cosmological constant, which he had designed to modify his equations of general relativity to allow them to produce a static solution, which he thought was the correct state of the universe. The Einstein equations in their simplest form model generally either an expanding or contracting universe, so Einstein's cosmological constant was artificially created to counter the expansion or contraction to get a perfect static and flat universe.[31] After Hubble's discovery that the universe was, in fact, expanding, Einstein called his faulty assumption that the universe is static his "biggest mistake".[31] On its own, general relativity could predict the expansion of the universe, which (through observations such as the bending of light by large masses, or the precession of the orbit of Mercury) could be experimentally observed and compared to his theoretical calculations using particular solutions of the equations he had originally formulated.

In 1931, Einstein made a trip to Mount Wilson to thank Hubble for providing the observational basis for modern cosmology.[32]

The cosmological constant has regained attention in recent decades as a hypothesis for dark energy.[33]

Einstein had a different theory until Hubble "Proved" him wrong through his observations. Again, we are in a cloud of dust that Hubble did not know about when he made his measurements. The equipment he used to do this is less accurate than what people have at home and this effectively ended the search for an answer. If Hubble was wrong, then it doesn't allow for Einstein work, his own WORDS. The bending of light that has been observed is better explained through atmospheric lensing.

Hubble was able to plot a trend line from the 46 galaxies he studied and obtain a value for the Hubble constant of 500 km/s/Mpc (much higher than the currently accepted value due to errors in his distance calibrations). (See cosmic distance ladder for details.)


Hubble's law - Wikipedia

en.wikipedia.org

This is so wrong it is terrible. It acts as if space is homogenous and it is in the article very clearly.

Idealized Hubble's law[edit]
The mathematical derivation of an idealized Hubble's law for a uniformly expanding universe is a fairly elementary theorem of geometry in 3-dimensional Cartesian/Newtonian coordinate space, which, considered as a metric space, is entirely homogeneous and isotropic (properties do not vary with location or direction). Simply stated the theorem is this:


Any two points which are moving away from the origin, each along straight lines and with speed proportional to distance from the origin, will be moving away from each other with a speed proportional to their distance apart.
Click to expand...
In fact this applies to non-Cartesian spaces as long as they are locally homogeneous and isotropic; specifically to the negatively and positively curved spaces frequently considered as cosmological models (see shape of the universe).

An observation stemming from this theorem is that seeing objects recede from us on Earth is not an indication that Earth is near to a center from which the expansion is occurring, but rather that every observer in an expanding universe will see objects receding from them.
 
Jan 9, 2020
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Every so often they revise Hubble's constant to ensure that they have the age of the universe right. They believe now 13.7GA. What is know about our solar system is that its moving toward the Hercules constellar. The next North Star is expected to be Vega in Lyra.
 
Jan 5, 2020
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I have been into the whole space scene for about 2 years now! It’s amazing to learn something new everyday in this community but here’s a question that may be a dumb one lol. When we say the universe is expanding are we saying just the trillions of galaxies are getting further apart or are is it expanding as in more and more galaxies are being formed in the universe?
Here’s a quark, maybe the universe is not that large at all...all the lights and galaxies are most likely gone and we are seeing their light, so we are looking back in time. Maybe it took the creation of the whole universe, to create our planet, and life that has all the ingredients of this universe.. also why do we say that we have not yet found life, look at the sun, it has cycles and also dies, just like everything.
I have been into the whole space scene for about 2 years now! It’s amazing to learn something new everyday in this community but here’s a question that may be a dumb one lol. When we say the universe is expanding are we saying just the trillions of galaxies are getting further apart or are is it expanding as in more and more galaxies are being formed in the universe?
 

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