Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 09/04/2016 20:50:01

Title: If space is empty how does this affect objects in it?
Post by: thedoc on 09/04/2016 20:50:01

Nadia Adam  asked the Naked Scientists:
   Hello, if space is empty, why don't  all the solid objects in the space break apart to fill the space  as air moves towards low pressure area?  Thanks


 
What do you think?

Title: Re: If space is empty how does this affect objects in it?
Post by: Tim the Plumber on 09/04/2016 22:18:44

Solids are where the atoms are locked together by the bonds between them such that they form a rigid structure.

Liquids are where the vibration of these atoms, temperature, almost breaks the bonds but there is enough external pressure to keep the substance together but not locked into a rigid structure.

Gas is what happens when the temperature is high enough that the chemical bonds between the outer electron shells of the molecules are not strong enough to stop the substance from breaking appart.

If you keep heating it up eventually the molecules break appart. This is called cracking (I think, at least it is in the oil industry).

If the temperature gets very high the bonds between the nucleus and the electrons are not strong enough to hold together and it's a soup of free atomic particles. This is called Plasma.

Large collections of atoms create large amounts of gravity that holds the planets and stars together.

I hope that in there somewhere is your answer.

Title: Re: If space is empty how does this affect objects in it?
Post by: evan_au on 10/04/2016 11:05:53

Quote from: Nadia Adam

air moves towards low pressure area?

If you released a liter of air into a vacuum, it would spread out to "fill" the vacuum - at a very low pressure.

Quote

why don't  all the solid objects in the space break apart to fill the space  as air moves towards low pressure area?

As Tim said, the atoms of a solid are locked together by strong forces, so if you released 1 kg of solid iron in a vacuum, the atoms won't separate from each other to fill the vacuum.

Another thing that can hold matter together is gravity.

• Jupiter has a deep gas atmosphere, but it doesn't spread out to fill the vacuum of space, because Jupiter's immense gravity holds it together.
  
• Similarly, the Sun's visible disk is made of plasma, but the Sun's even stronger gravity holds it together, with just some slight leakage into space in the form of the solar wind.