# Special and General Relativity Forum Page 186

Participate in expert discussion on special and general relativity topics. Relativity is the dependence of various physical phenomena on relative motion of the observer and the observed objects. Mainstream physics only.
• Posted
Replies
3
Views
2K
• Posted
Replies
6
Views
4K
J
• Posted
Replies
10
Views
3K
• Posted
Replies
12
Views
4K
• Posted
Replies
6
Views
3K
• Posted
Replies
3
Views
3K
• Posted
Replies
27
Views
5K
• Posted
Replies
13
Views
4K
• Posted
Replies
4
Views
7K
• Posted
Replies
3
Views
4K
• Posted
Replies
8
Views
5K
T
• Posted
Replies
6
Views
12K
• Posted
Replies
8
Views
6K
P
• Posted
Replies
2
Views
4K
B
• Posted
Replies
7
Views
4K
• Posted
Replies
30
Views
7K
• Posted
Replies
1
Views
4K
• Posted
Replies
18
Views
6K
C
• Posted
Replies
2
Views
9K
C
• Posted
Replies
1
Views
6K
• Posted
Replies
4
Views
5K
• Posted
Replies
12
Views
4K
• Posted
Replies
13
Views
5K
• Posted
Replies
6
Views
4K
• Posted
Replies
5
Views
5K
• Posted
Replies
3
Views
5K
• Posted
Replies
22
Views
7K
• Posted
Replies
3
Views
5K
• Posted
Replies
3
Views
4K
• Posted
Replies
5
Views
5K
• Posted
Replies
3
Views
5K

### Relativity

General relativity is just describing gravity in a relativistic setting. The equivalence principle hints to the idea that gravity is spacetime curvature.

In special relativity much attention is given to inertial frames, because they are equivalent. However, SR can perfectly handle other frames like accelerating ones, just as in Galilean relativity (classical mechanics) you can describe accelerating observers.

The key difference between classical mechanics and relativity is that, while in classical mechanics only linearly accelerating observers can locally pretend they are in a gravitational field, in GR every observer can locally pretend he/she is in a gravitational field. The class of "equivalent observers" is thereby enhanced.