Gravitational Field Lines
Question:
How can a mass itself gives out fields, and has field lines from
other mass going into its core? Or are there any external agents
which induce a mass's fields?
Answer:
There are several ways to think about the gravitational
interaction between two objects. One, as you suggest is to
imagine a field emanating from each object which has an effect on
the other object. To help visualize this business, we picture
"field lines" or "lines of force" connecting
the two bodies. One of the problems with this way of thinking
about gravitation is the difficulty you have already experienced
in picturing how these lines are produced and how they bring
about the gravitational interaction. The lines are a hypothetical
construct to help us visualize the situation, not necessarily
having any physical reality themselves.
I find it more convenient to imagine that a gravitational
field is simply a condition of space, brought about by the
presence of matter in that space. Then other matter sharing that
neighborhood in space is effected by this condition. For more
detail on these ideas look at
http://mcanv.com/p1ns.html.
This information is brought to you by M. Casco Associates, a
company dedicated to helping humankind reach the stars through
understanding how the universe works. My name is James D. Jones.
If I can be of more help, please let me know. JDJ