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

What keeps an object together

  1. Dec 21, 2012 #1
    A human for example, or a bottle. What force is keeping the trillions of molecules bound together so you don't wake up one morning and weigh 20lbs lighter?

    Also is it possible to extract a single molecule from me and examine it? Either a skin molecule or a muscle molecule or something.
    Last edited: Dec 21, 2012
  2. jcsd
  3. Dec 21, 2012 #2


    User Avatar
    Science Advisor

    The principal force holding all ordinary matter together is electromagnetic.

    Removing one molecule is difficult - instruments probably don't exist.
  4. Dec 21, 2012 #3


    User Avatar
    Staff Emeritus
    Science Advisor

    As has been said, the electromagnetic force is what holds atoms and molecules together and to each other. The EM force is one of four fundamental forces of nature that we know of. These four forces are the causes of ALL interactions between ALL objects. The other three forces are:
    Strong Force (Also known as the Color Force)
    Weak Force
    Gravitation (Gravity)

    The Strong Force is what holds certain subatomic particles together. For example, the nucleus of every atom is full of positively charged protons. Since electric charges repel other electric charges of the same polarity, there must be some force holding them all together. Since there can be over 100 protons in a single nucleus, this force must be VERY strong in order to keep them together. This is why it's named the "Strong" force!

    The Weak force is responsible for certain kinds of particle decays and interactions. Its range is very very short and the frequency that things happen because of it is generally much lower than other forces, hence the name "Weak" force.

    Gravitation is gravity obviously.

    All 4 forces are required for the universe to work the way it does. Without even one of them we would not be here today. For example, without the weak force the Sun would not undergo nuclear fusion in its core and would never have been able to sustain the Earth.

    Molecules are made up of atoms, which are made up of subatomic particles. Your body is made up of molecules chained together in many different ways. However, many of these molecules are used in different places, so there really isn't such thing as a "skin molecule". The same type of molecule used in your skin can also be used in many different places too.

    Start here and go to the different articles linked if you want to learn more: http://en.wikipedia.org/wiki/Fundamental_interaction
    Also here: http://en.wikipedia.org/wiki/Chemical_element
  5. Dec 22, 2012 #4
    Thanks :)
  6. Dec 22, 2012 #5
    You can indeed manipulate single atoms and molecules adhered to surfaces. There are famous pictures of STMs and AFMs doing just this.
  7. Dec 22, 2012 #6
    Why objects stay together has been explained, but to your question of "removing a single molecule"


    Zooming in will show you both a skin cell and a carbon atom. I don't think I'll ever be able to grasp the scale of the molecular level.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook