Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Can the size of an atom change?

  1. Dec 6, 2011 #1
    I've been searching and trying to find an answer to this. I'm not scholar or physics major. I'm asking for some guidance about this subject.

    The big bang theory, leaves me with the impression that atoms can change size.

    Is this true?

    Can gravitational forces compress, can atoms become smaller?

    What regulates an atom's size?

    Can adjusting the space/time fabric change the size of an atom?

    Thank you for your time. I'm really wondering how all the atoms can fit into the space of a green pea, as computer models suggest.
  2. jcsd
  3. Dec 6, 2011 #2


    User Avatar
    Science Advisor

    As far as I know gravitation does not effect the size of atoms. Size for atoms is a difficult concept, but the simplest way to look at it is in terms of energy. Increasing the energy of an atom means the electrons are in more energetic levels which take up more room.
  4. Dec 6, 2011 #3
    Then forget gravity.

    If there is space inside each atom, would it not also have to obey the expansion of space?


    Last edited: Dec 6, 2011
  5. Dec 6, 2011 #4


    User Avatar
    Science Advisor

    Why would you say "The big bang theory leaves me with the impression that atoms can change size"?
  6. Dec 6, 2011 #5
    Because if expansion of space is true, wouldn't the size atoms be related to the size of the Universe?
  7. Dec 6, 2011 #6


    User Avatar
    Gold Member

    Not at all. The expansion of space has no effect on gravitationally bound objects, such as clusters of galaxies, galaxies, solar systems, planets, you, atoms, etc.
  8. Dec 6, 2011 #7
    So, space inside each atom is not effected by the inflation of space? Is that space inside an atom special?
  9. Dec 6, 2011 #8


    User Avatar
    Gold Member

    Has nothing to do with space, it's the presence of a force that binds the objects together. For macro objects, it's gravity, for micro objects, it's sub-atomic forces.
  10. Dec 6, 2011 #9
    Okay. I was just under the impression that if gravity caused macro objects to be pulled towards each other, the galaxies would not be getting farther apart, like they are doing.
  11. Dec 6, 2011 #10


    User Avatar
    Gold Member

    They are getting farther apart precisely in the empty gaps where gravity is too weak to pull them together.
  12. Dec 7, 2011 #11
  13. Dec 7, 2011 #12


    User Avatar
    Gold Member

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook