# Perfect reference frame

1. Dec 16, 2012

### aayushgsa

We have a problem of perfect reference frames( according what we are taught in school)
If universe is expanding, the so called fixed stars are also moving.
According to the special relativity, the speed of light is constant in every reference frame,
So if we let light as the perfect reference frame, will not be the problem of reference frames solved?

2. Dec 16, 2012

### Staff: Mentor

What do you mean with "light as the perfect reference frame"? How do you plan to use light to describe any reference frame?
Which "problem of reference frames" do you mean?

3. Dec 16, 2012

Staff Emeritus
Let's go back a bit. Do you know what a reference frame is? It sounds like you might not.

4. Dec 17, 2012

### aayushgsa

I think the frame of reference is a set of points from which we find out the position, and by that relative speed.
And my point is that if we take the relative speed of anything with reference of light,instead of fixed stars,than it would be perfect because light never accelerates or decelerates. As universe's expansion is speeding, fixed stars are also accelerating so if we define any speed in reference to fixed stars, it would be wrong, but as light do not accelerates cant we define all velocities with respect to light?

5. Dec 17, 2012

### Staff: Mentor

A reference frame allows to give a position and velocity for an object - as seen by this frame. It is not "the position/velocity of the object" (that does not exist).

The relative speed of anything relative to light is the speed of light (as seen by the object) or depends on the reference frame (if you just subtract both velocities). This is a problem even if you ignore expansion of the universe, or stars, or any other objects.