If you go from Edinburgh Waverley to Glasgow Central, it takes anywhere between just over an hour to an hour and a half. Times variable.
If you go from Edinburgh Waverley to Glasgow Queen Street, it takes a pretty reliable 48-53 minutes (depending whether it stops in Motherwell or not, I think) and trains run four times an hour. (Central and Queen Street are within 10 minutes walk of each other.)
The very cheapest method of travelling is to go with 3 friends who'll all be going and coming back at the same time as you - that will cost something like £3.75 apiece, but it's a group ticket, and legally it's the same group who travel in and out.
Other than that: it will cost you between £10 and £20, depending whether you can get a cheap day return.
I don't know about the price for coach travel, but I wouldn't risk it myself if I were travelling to/from either Edinburgh or Glasgow in rush hour: the traffic can add quite a bit of time to the trip.
By train...
If you go from Edinburgh Waverley to Glasgow Queen Street, it takes a pretty reliable 48-53 minutes (depending whether it stops in Motherwell or not, I think) and trains run four times an hour. (Central and Queen Street are within 10 minutes walk of each other.)
The very cheapest method of travelling is to go with 3 friends who'll all be going and coming back at the same time as you - that will cost something like £3.75 apiece, but it's a group ticket, and legally it's the same group who travel in and out.
Other than that: it will cost you between £10 and £20, depending whether you can get a cheap day return.
I don't know about the price for coach travel, but I wouldn't risk it myself if I were travelling to/from either Edinburgh or Glasgow in rush hour: the traffic can add quite a bit of time to the trip.