Using CGS or SI Units: When to Choose?

[Saketh]

I have a simple question.

I understand the quantitative differences between cgs and SI units, but when will I be expected to use one over the other? For example, do physicists prefer one set of units?

Thanks for the help.

 

[ranger]

I really doesn't matter which system you use. The important thing is to be consistent with units. I was taught with the SI system, so I have come to prefer it, but that's not to say that it is better than cgs. Its a matter of preference and being able to move from one system to another. In fact its better that you be able to move between systems. But I guess the times will soon change and one can only speculate that the SI will out do cgs, as SI is widely used.

 

[Crosson]

The short answer is that cgs is on the way out and mks is on the way in.

 

[rbj]

The short answer is that cgs is on the way out and mks is on the way in.

except the real, hard-core physicists keep saying that the Fine-structure constant is:

$$\alpha = \frac{e^2}{\hbar c}$$

which is the cgs way of saying it. the MKS (and general unit system) way to say it is:

$$\alpha = \frac{e^2}{\hbar c (4 \pi \epsilon_0)}$$