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Author Topic: What does 'Steady State' mean?  (Read 4572 times)

Offline The Scientist

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What does 'Steady State' mean?
« on: 19/12/2010 10:46:34 »
Is it a period of something? Please elaborate. Thanks!


 

Offline Chemistry4me

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What does 'Steady State' mean?
« Reply #1 on: 19/12/2010 10:56:05 »
I believe the words 'steady state' can be used in a lot of places, but one I can think of is that when a system is in a steady state, it has properties that are unchanging over time.
 

Offline Chemistry4me

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What does 'Steady State' mean?
« Reply #2 on: 19/12/2010 10:59:05 »
There is also the Steady State theory as an alternative to the Big Bang theory
 

Offline Soul Surfer

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What does 'Steady State' mean?
« Reply #3 on: 19/12/2010 11:50:35 »
Steady state was a term used to describe the whole universe.  It is more a philosophical concept than a scientific theory. It is based on the concept that an "infinite" universe that is, one without any boundaries of space and time must always look the same when viewed on a large enough scale of space or time.  This idea goes right back to early pre scientific philosophy.

This has always been at the back of early scientific observations of the universe and was essentially not a hot topic.  Even Einstein in his relativistic models of the universe right at the beginning of the 20th Century when he found that the equations would not allow a universe  to be be stable it must either expand or contract added what he called a cosmological constant to stabilise the universe.  This was accepted by all as normal until in the early 20th century Hubble observed that the universe was expanding on the largest scales that he could observe.  This really put the cat among the pigeons because if the universe was expanding it must in the past have been small and highly compressed. 

In the late 40s and 50s Fred Hoyle one of the best mathematical physicists of the day had another idea.  Now, he had worked out in detail how nuclear fusion could power stars and indirectly shown how in the hot rapidly expanding universe nuclear synthesis would be limited and allow stars to form when things cooled down.

Now he also suggested as a sideline that, if for some reason an atom of hydrogen appeared in quite a large volume of space over a large time (if I remember rightly this was one atom in a volume equal to that of St Paul's Cathedral in London once a year.  This was just about unobservable then) the universe  could be stabilised even though the universe was expanding.  This he called the "continuous creation" steady state theory.   This was a very simple postulate and disprovable and subsequent measurements disproved it and showed clearly that our observable universe did have a beginning a middle and an end  Fred knew this but defended the idea of a steady state universe to the last..  For this Fred was criticised and his really great work disregarded a rather sad situation.

However that may not be the end of the story.  It is now becoming accepted that there could well be a multitude of other universes vaguely similar to ours in what is called the multiverse.  These are all unobservable to us but theoreticians could model them.  This could mean that the steady state still exists and that if one could look at a vast array of universes each in a different stage of development on a large enough scale the steady state multiverse could exist.

This could mean that the philosophical point that Fred Hoyle was trying to defend with is disproved steady state theory was valid He did not have today's modelling resources or information.  multiple universes were not really thought of until much later.
« Last Edit: 19/12/2010 12:13:24 by Soul Surfer »
 

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What does 'Steady State' mean?
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