The Naked Scientists

The Naked Scientists Forum

Author Topic: Dark Matter...  (Read 1957 times)

Offline Nobody's Confidant

  • Neilep Level Member
  • ******
  • Posts: 1802
  • So loud silence can be.
    • View Profile
Dark Matter...
« on: 17/09/2007 17:53:27 »
I heard it's the stuff that holds the galaxy together...is this true?


 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Dark Matter...
« Reply #1 on: 17/09/2007 18:36:08 »
Actually Dark Matter is the stuff that accumulates between your toes and is discovered when ewe take your socks off !..Yes this is true !!


Actually, there's a lot of info on the site about Dark Matter !...but there's always room for one more thread so I'll leave this thread be for a passing Dark Matter mechanic to meander in an answer for ewe.

For all we know..the stuff that does keep the galaxy together may well be the dark matter between your toes !!...I think it is !

 

Offline Soul Surfer

  • Neilep Level Member
  • ******
  • Posts: 3345
  • keep banging the rocks together
    • View Profile
    • ian kimber's web workspace
Dark Matter...
« Reply #2 on: 17/09/2007 18:51:44 »
This is true because if you suddenly removed the dark matter the galaxy would fly apart because the angular momentum that the stars have is far too great for it to be stable without the missing mass represented by dark matter.  However this is not a good or a valuable description because if there were no such thing as dark matter in our universe galaxies would exist but would look and behave very differently from the way they do now because of the existence of dark matter. So a better way of putting it is that galaxies look and behave the way we see them because a large amount of dark matter allows them to have much more angular momentum before they fall apart.

This is a good example of what I would call the journalistic approach to science in which the most spectacular aspects of concepts are presented as the most important, without putting these things in their correct scale and context.  The expression above suggests that dark matter is absolutely vital for the functioning of the universe as we know it.  However this is not true.  Without dark matter almost everything that we know and love would be much the same but the night sky would look a bit different because the galaxy would be of a different size and stellar distribution.

Another example is  the concentration on supernovae as a typical process in the life of a star when in fact very few stars (only the very biggest) will ever become supernovae and most stars live for most of their lives on the main sequence in which they have a very stable brightness and do very little before either fading out or gently puffing away their atmospheres to become white dwarfs which just spend millions of millions of years slowly cooling down.

OK in this gentle puffing away of the atmosphere for the sun (in about 4 thousand million years)the earth will be fried but thats an insignificant feature in the life of our sun.  the destruction of the earth will have no significant effect on this process.
 

The Naked Scientists Forum

Dark Matter...
« Reply #2 on: 17/09/2007 18:51:44 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums
 
Login
Login with username, password and session length