# What exactly is it being bent by gravity?

1. Mar 13, 2005

### Tapsnap

Is it space that is bent by gravity. Or is it our perception of what we are seeing, bent by gravity? By that I mean, is light being bent, to give us the appearance of things being where they are? Can somone clarify?

2. Mar 13, 2005

### ohwilleke

The usual way of explaining GR to layman implies that space itself has a substance. Theories that actually have this premise are called "ether theories". Mainstream scientists generally do not view GR as an ether theory, however. The geometric manifestation of the gravitational theory might be more mainstream. I would defer to my betters for a more precise statement, however.

3. Mar 13, 2005

### Hurkyl

Staff Emeritus
Here are some observable consequences of deformations of space-time. (Not just of space!)

(I hope I have these right)

It can make the angles of a triangle not sum to 180 degrees.
It can stretch things.
It can squeeze things.
It can do both of the above in different directions.
It can cause straight lines to intersect in two or more points.

4. Mar 13, 2005

### Tapsnap

It can make the angles of a triangle not sum to 180 degrees.
It can stretch things.
It can squeeze things.
It can do both of the above in different directions.
It can cause straight lines to intersect in two or more points.

But is it that we observe them to be bent because the light was bent on its way to us or is it that the objects or space is actually bent?

5. Mar 13, 2005

### Chronos

We observe things the way we do because they agree with the GR interpretation. If you don't understand that, ask a question that makes sense. I am losing patience otherwise.

Last edited: Mar 13, 2005
6. Mar 14, 2005

### Tapsnap

Here's a question - Why don't you get off your high horse and be useful to someone who is looking for some information.

7. Mar 14, 2005

### Phobos

Staff Emeritus
Gravity is the name we give to the behavior of space with respect to matter/energy moving through it. The best explanation we have to understand what gravity is comes from General Relativity. The reason that gravity bends a beam of light is essentially the same reason why something falls to the floor when you drop it. You can find comfirmations of the malleable nature of space through past and current measurements of frame dragging (e.g., Mercury's orbit around the sun or recent experiments using satellites orbiting the Earth).

I think a reality vs. perception discussion would be better held in the philosophy forum. Based on that, plus the growing heated argument, I'm going to close this discussion.