# Is it possible? (faster than light in a medium)

1. Nov 23, 2009

### IPhO' 2008

If we have a tank which full of water.Then,emitted the light into the tank.The speed of light is c/n . If we can run faster than c/n. We will run faster than light.
Is it possible?

2. Nov 23, 2009

### JesseM

Re: Is it possible?

Yes, the impossibility of traveling faster than light only applies to the speed of light in a vacuum.

3. Nov 23, 2009

### cfrogue

Re: Is it possible?

You are gauging the speed of light I assume from one medium to another.

It will max out at c.

4. Nov 23, 2009

### Staff: Mentor

Re: Is it possible?

Well, we can't run faster than the speed of light in water, but hypothetically, if there is a material with a refractive index that causes light to travel at an apparent speed less than running speed, we could run faster.

5. Nov 23, 2009

### cfrogue

Re: Is it possible?

http://www.news.harvard.edu/gazette/1999/02.18/light.html

6. Nov 23, 2009

### George Jones

Staff Emeritus
Re: Is it possible?

Instead of us running, use an electron moving through the water. If the election moves faster that the speed of light in the water, Cerenkov radiation is emitted. This radiation is routinely observed.

7. Nov 23, 2009