Matching gravities

Sorry, reading again. How does one make sure the starter gravity approximates the OG of the wort to prevent osmotic shock to the yeast. Just being a little academic here - it's my background. Please indulge my curiosity. It may not really mean too much except with HG worts, but I'd like to hear if anyone pays any attention to this.

I am no expert, so take this with a grain of salt. I have done a little bit of reading on starters and it seems like people try and keep them in the 1.030-1.040 range. I think Jamill even suggested that he keeps the gravity in the starter at the lower end so the yeast get going, but they are hungry when you pitch them. There is some good info here:

Fourteen Essential Questions About Yeast Starters

One thing I found particularly interesting is that he suggests the same gravity in a starter for a big beer because a high gravity starter will stress the yeast.

If you are making a starter, you are on the right path anyway. I don't think this is a problem as long as the starter wort is around 1.040 and no higher than 1.050. Even with a higher gravity beer.

The time when you need to worry about shocking yeast is when it is dry. Properly re-hydrating will significantly increase viability. No need to make a starter though. If you are really worried, put in a teaspoon of wort while re-hydrating to get it slowly used to a sugary solution.

starters are used to wake up the yeast and get them eating but not enough to stress them out. Especially when pitching into higher gravity beers, its like throwing frozen beef in a scalding hot pan, it works for a moment but it goes down hill fast after that. it is always best to wake up the yeast with a nice bath then into the pool. it also helps build up the yeast colony so they will have the vitality for a nice quick fermentation. i think there is a recipe for 1 quart of water to 1/2 cup of dme will get you to 1.040 sg.