https://energyeducation.ca/wiki/index.php?action=history&feed=atom&title=Time_scale_of_the_universeTime scale of the universe - Revision history2026-10-07T14:05:58ZRevision history for this page on the wikiMediaWiki 1.44.0https://energyeducation.ca/wiki/index.php?title=Time_scale_of_the_universe&diff=10424&oldid=prevJmdonev: 1 revision imported2021-10-15T19:13:38Z<p>1 revision imported</p>
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</td></tr></table>Jmdonevhttps://energyeducation.ca/wiki/index.php?title=Time_scale_of_the_universe&diff=10423&oldid=prevenergy>Jmdonev at 18:49, 27 May 20212021-05-27T18:49:59Z<p></p>
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[[category:Lecture 1A a changing planet]]<br />
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<onlyinclude>The '''time scale of the universe''' refers to the relative size of the universe and all events occurring within it.</onlyinclude> Best estimates show that the universe has been around for 13.8 billion years. It started with the [[Big Bang]], and [[size of the universe|expanded rapidly]]. All of the [[energy]] and [[mass]]<ref>also, oddly, time and space, see here for a lecture by Prof. Steven Hawking on the subject, although we go with the 13.8 billion year rather than 15 billion year time that he gives: http://www.hawking.org.uk/the-beginning-of-time.html.</ref> in the universe seems to come from that one gigantic explosion that is clearly the biggest explosion that is known about. Everything that exists was formed either directly or indirectly from the Big Bang.<br />
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Roughly 5 billion years ago, 8 billion years <u>after</u> the Big Bang, a star exploded<ref>See [http://hyperphysics.phy-astr.gsu.edu/hbase/astro/nova.html#c1 nova] and [http://hyperphysics.phy-astr.gsu.edu/hbase/astro/snovcn.html#c2 supernova] on hyperphysics for more information.</ref> and formed the [[solar system]], including the Earth, over the course of hundreds of millions of years. This means that Earth was formed 4.6 billion years ago, quite a bit after the Big Bang. Life formed fairly soon after the Earth formed. The 'life' link in visualization below<ref name=Chrono> Chronozoom.com Copyright (C) 2013. The Outercurve Foundation. All rights reserved.</ref> shows this. By contrast, genus ''Homo'' has only been around for 250,000 years, and of that time evidence exists for only 5000 years of recorded history.<ref>Which we've defined as history confined to written records</ref><br />
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Large time scales of millions or billions of years can be difficult to properly imagine. The [http://www.chronozoom.com/ Chronozoom website] is a project dedicated to showing scale comparisons in the enormous time scale of the universe. Their interactive visualization shows the known past timeline of the entire cosmos. Click on the 'Earth' link along the top, or inside the 'Earth and Solar System' box in the image to zoom into the last 4.5 billion years. Click on the 'prehistory' link along the top to get an idea of human prehistory. Click on the 'humanity' link along the top to get an idea of the last 5000 years of human history. Click on the box in the upper right hand corner to see the industrial revolution, when [[coal]] started getting used extensively to change the way humans live.<br />
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==References==<br />
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