# Change in grav?

1. Jul 22, 2004

### Phymath

maybe im having dirreha of the mind but has anyone ever researched, what happens when we change a gravational field does it create someother field? like idk how'd we do this but you'd need to make a huge massive thing and then covert most of it to enegry in a matter of less then a second, does anyone think that would create another field? kinda like EMR? or am i just rambling about nothing, but if it does create another field shouldn't any accelerating mass create a changing grav field? (such as an orbiting moon) let me know what all of u think?

2. Jul 22, 2004

### chroot

Staff Emeritus
Energy couples gravitationally just like mass does. Converting a lump of mass to energy will not change its gravitation (assuming you can keep the energy in the same volume as the original mass).

When masses are moved around, gravitational waves are produced which carry away energy. This is in analogy to moving charges, which create electromagnetic waves.

- Warren

3. Jul 22, 2004

### Phymath

ok...so we know EMR is made of E fields and B fields, what do u think a G field is composed of?

4. Jul 22, 2004

### chroot

Staff Emeritus
In truth, the notion that E and B are distinct is false. They are really just two sides of the same coin. In most higher physics, they are treated together.

If gravity turns out to be a gauge theory, the graviton will be the quantum of the gravitational field, as the photon is the quantum of the electromagnetic field.

If not, then gravity is simply different from the other three forces, and is not mediated by any force-carrying particle. General relativity describes gravity as the curvature of space. Gravitational waves are perfectly well-defined in general relativity, but there is no such thing as a graviton.

- Warren

5. Jul 22, 2004

### Phymath

yet... but thanks for all the insite warren, can u tell what does GR say about Grav waves, if i remember right, isn't that when a mass is "dropped" on the Space-time contin. it creates a ripping wave like a stone in a pond, while curving the space-time around it like a rubber sheet?

6. Jul 22, 2004

### chroot

Staff Emeritus
GR doesn't say anything about analogies like water waves or rubber sheets. It also doesn't say anything about a "space-time continuum," because such a thing doesn't exist. What it DOES say is that there are wave-like solutions to Einstein's equation.

- Warren

7. Jul 22, 2004

### Phymath

whoa, what are u talking about?! what do u mean it says there is not space-time contin?

8. Jul 22, 2004

### chroot

Staff Emeritus
Get a book on general relativity. Note that there is no reference to anything called a "space-time continuum" anywhere in it. The term "continuum" simply doesn't mean anything relevant to science.

What there is is a four-dimensional manifold called simply "spacetime."

- Warren

9. Jul 22, 2004

### Phymath

dude are siersously going to fight me over a word that means the same thing! holy crap man, but thanks for the gravity help lol

10. Jul 22, 2004

### chroot

Staff Emeritus
Yes, I certainly am going to correct you when you use words in improper ways. Scientists are sticklers about proper word use, because it's critical for us to understand each other. If you intend on continuing in your science education, get used to it.

- Warren