Difference between young and old boss - (Jan/22/2008 )
What is difference between young and old boss. which one is better. If i have to choose according to the age, for the future work.
I would predfer young........
I've had both. An older boss is well established, lets you work on your own project at your own pace and is well respected in the field. A younger boss is more driven to get published and get tenure. You may not get to work on project of your choice and he/she may be more controlling. If both have adequate funding and publish good papers (which should be your top priorities when picking someone to work for), then I would choose the older boss over the younger for the above reasons.
Personally I wouldn't let age influence my decision for who I work for, I don't believe that people have certain characteristics just because of their age. Characteristics such as being driven, being a micro-manager, or being relaxed and lenient are not determined by someones age, but by who they are as a person regardless of age.
Chose a boss you respect and feel you can work with.
Never work in a husband-and-wife lab.
Never have two mentors who are husband and wife.
Chose a boss you respect and feel you can work with.
I didn't mean to sound like I was quoting stereotypes, and you are correct that such characteristics can't be completely determined by age. But I do think that there is a tendency for newly hired assistant professors to be much more driven because they feel the pressure to get tenure. One thing that can be very helpful is to talk to other people in the lab that you are thinking of working in. They can tell you what the boss is like and can give you an idea if that person will be a good fit for you.
Thats good advice, Smu2 
Another thought- an older prof. is likely to be more absent from the lab (and country)- with either committees or lecturing etc., so might not be around so much if you need advice- therefore the lab members are likely to be important people to know and get along with.
A younger boss is likely to be in the lab much more, so is more accessible for advice and the lab is smaller (my first postdoc was me and the boss- I helped set up the lab and stuff which was really interesting).
Anyway, either way- the other people you might be working with are very important since you're likely to be around them more than your Prof. Make sure you meet them in an interview.
Just my two cents
Lost
I agree with Smu2
An older boss do not need anymore to prove anything. They have already a good position, and are more willing to help you to get a position.
However, this is a general trend, and there are exceptions.
In my case my boss is older, no life except sitting in the office, according to me its not a good idea, science never say not get married or not enjoy life. May be with other activity you can improve your scientific life. My lady boss is looking for slave and she found me the perfect one for that, but hundred of km far from my home i did not traveled to become slave. So i donot think so older boss is helpful for some one. Older boss can be more expert in his field but the problem is either he is willing to get you expert in his or her field or not. I think he will never allowed you to do that. Science is knowledge, if knowledge is not delivered they why to be slave for the rest of life for some data measurement.
An older boss do not need anymore to prove anything. They have already a good position, and are more willing to help you to get a position.
However, this is a general trend, and there are exceptions.