Four Questions

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bigpic

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Four basic questions ( current estimates ) :<br /><br />1. After the BB and then inflation - how long did it take for stars and galaxies to form.<br /><br />2. How long ago did "most" of the stars and galaxies we see today form.<br /><br />3. How long after the BB and inflation did the slowing expansion begin.<br /><br />4. How long ago did the the accelerating expansion begin.<br /><br />Thank you. <br /><br />
 
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nexium

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I believe 1 and 3 are less than a billion years 3 may be less than a million years/ I am guessing. Most of the naked eye stars formed about 4.6 billion years ago about the time our sun and Earth formed. The very distant galaxies formed 12 to 13 billion years ago. Neil
 
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a_lost_packet_

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Here's a quick link to <i>the very beginning moments</i>: Early moments of the Big Bang Later moments and the formation of the Universe: Timeline of the Universe<br /><br />1) Matter began to condense as the Universe cooled around (yr)300 thousand.<br />2) Galaxies began to form around (yr) 600 million.<br />3) Ballpark= +10 <sup>-35</sup>seconds from start. It was extremely brief in duration. Check WMAP for more data on that. Is not confirmable but is a generally accepted theory that answers most questions.<br />4) I don't think we know. Perhaps it has been ongoing since mass first formed.<br /><br />Quick and dirty answers, someone else may have better ones.<br /><br /><br /> <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>
 
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rogerinnh

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The entire universe was created yesterday at precisely 3:04 pm Eastern Time, fully formed, exactly as it now appears, with all the stars and galaxies and gas, and even with your memories of events that "happenned" before yesterday, including the concepts of the Big Bang, inflation, etc. Nothing actually existed at all prior to 3:04 pm yesterday, it just looks that way.
 
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a_lost_packet_

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Great! Thanks RogerInNM!<br /><br />That means all my warranties are still current. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>
 
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bigpic

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Update - Star making peaked 5 billion years ago ( University of Pennsyvania 4-12-04 )
 
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newtonian

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bigpic - on #2 -<br /><br />If you mean see with the naked eye, see the Big Dipper thread in Ask the Astronomer section.<br /><br />Most of these stars are much younger than our sun.<br /><br />Also, Hubble is searching for a much earlier star making period - very massive and therefore short-lived stars which are thought to have existed by their radiative effects.<br /><br />They would have preceeded galaxies and quasars.
 
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bigpic

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Four basic questions ( current estimates ) : <br /><br />(WOULD LIKE TO BUILD ON THE FOLLOWING ANSWERS AS NEW DATA COMES TO LIGHT OVER THE YEARS AND KEEP THE ANSWERS UP TO DATE - HOPE OTHERS MIGHT FIND THESE QUESTIONS INTERESTING. ) <br /><br /><br />1. After the BB and then inflation - how long did it take for galaxies to form. <br /><br />ANSWER - Galaxies began to form about 600 million after BB (THANKS A-LOST-PACKET ) <br /><br /><br />2. How long ago did "most" of the stars and galaxies form. <br /><br />ANSWER - 4.6 billion years ( THANKS NEIL ) <br />ANSWER - Star making peaked 5 billion years ago (University of Pennsyvania 4-12-04 ) <br /><br />3. How long after the BB and inflation did the slowing expansion begin. <br /><br />ANSWER - less than one million years (THANKS NEIL) <br /><br />ANSWER - Most cosmologists seem to feel that the Universe began in a sudden expansion, from a tiny cosmic singularity, anywhere from 12 billion to 15 billion years ago. Then gravity began slowing down that early expansion. And then, about 4 billion to 8 billion years ago, the Universe began to accelerate its expansion once again. <br />http://groups.msn.com/AstrophysicsGroupWest/10billionyearolddiscoveryinspace.msnw<br /><br />A length of 10-43 seconds is known as Planck time. At this point, the force of gravity <../../g/gr/gravity.html /> separated from the other three forces, collectively known as the electronuclear force <../../e/el/electronuclear_force.html><br />http://www.fact-index.com/t/ti/timeline_of_the_big_bang.html<br /><br />4. How long ago did the the accelerating expansion begin. <br /><br />ANSWER - I heard Paul Steinhart (Princeton) say that the acceleration picked up after (most ?) the stars and galaxies formed. <br />ANSWER - "Astronomers estimate that the acceleration of the u
 
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