# Special case of Relativity

1. Mar 23, 2015

### vikram chawan

please can u resolve my doubt regarding this ....."What if i fixed a chair inside a sphere and i am sitting on it and it is not rotating whereas the sphere is rotating with the speed of light ?" "Will time be different for me inside the sphere and for the people outside?"

2. Mar 23, 2015

### Staff: Mentor

No.

3. Mar 23, 2015

### vikram chawan

But what if i am rotating with the speed of light with the sphere???will the time be different then??

4. Mar 23, 2015

### Simon Bridge

... taking "rotating at the speed of light" to mean "rotating with a speed very close to the speed of light": I agree with russ_watters.
realize you cannot rotate at the speed of light, since you have mass.

Further, when you talk about speed, it is important to say what the speed is relative to.
In the first case we can talk about the speed of the sphere relative to the chair, since you specified that it was stationary.

In the second case, you are spinning in the frame of reference of "everyone else" (i.e. outside the sphere), and we assume that "everyone else" are inertial observers.
You should be able to do the math for that.

5. Mar 23, 2015

### Staff: Mentor

There is no such thing as "rotating with the speed of light". The speed of light is a linear speed, not a rotational rate (and yes, as Simon says, you can't reach the speed of light, just something close to it...if you have the right apparatus). However, if you were to spin at a high rate (without disintegrating), different parts would experience different time dilation based on the particular linear velocity they had. We have clocks that are accurate enough they could be mounted on/next to a centrifuge to measure that.

6. Mar 23, 2015

### vikram chawan

Thank you so much for the answers......