# B Speed of light and higher dimensions

1. Jan 12, 2017

### bellatrix gray

will there be any effect on the speed of light ,when it travels from higher dimensions to three dimensions of space ?

2. Jan 12, 2017

### Orodruin

Staff Emeritus
What do you mean by this?

3. Jan 12, 2017

### bellatrix gray

i meant, what is the speed of light at higher compressed string theory dimensions?

4. Jan 12, 2017

### Staff: Mentor

It never happens that light travels from higher dimensions to 3D space. In theories with additional compact dimensions, those compact dimensions exist at each point in the non-compact dimensions. So it never leaves the higher dimensions, it is always in both.

Last edited: Jan 12, 2017
5. Jan 12, 2017

### bellatrix gray

and will there be any change ,while it is travelling in higher dimensions?

6. Jan 12, 2017

### Staff: Mentor

Again, it is always traveling in all dimensions.

7. Mar 7, 2017

### ccgjg

does this mean the universe our universe exists within shares the speed of light?

8. Mar 7, 2017

### rootone

The speed of light is what it is.
In the Universe we know, the speed light can be measured, it is constant.
There s no reason I know of why light must travel at that speed. but it does.

Last edited: Mar 7, 2017
9. Mar 7, 2017

### Staff: Mentor

Our universe is not known to exist within another universe, so your question isn't answerable.

10. Mar 12, 2017

### Debaa

Like gravity?

11. Mar 12, 2017

### Debaa

I think he/she means that just like the bread slice example of multiverse which explains why gravity is weak, maybe speed of light is also distributed in the multiverse.

12. Mar 13, 2017

### JasonWuzHear

I think the OP is just wondering if light can have a velocity component in an extra dimension which would make the projection of the velocity in our usual number of dimensions look smaller.

13. Mar 15, 2017

### Khashishi

My (naive) understanding is that the extra dimensions are smaller than the typical wavelength of particles, so there is no room to "move" in those directions. I suppose it should be like moving in a waveguide. Are there different waveguide modes?