There is a postdoc from another group in my department that frequently helps PhD students in his area when they have questions or want to talk about a particular subject. I would like to know if this is expected/normal. In other words, can I go to a postdoc looking to talk and ask questions related to our field?
In other words, can I go to a postdoc looking to talk and ask questions related to our field?
It depends on what you mean by "can", as well as the culture in your field and department.
If you are asking whether it's an ethical and reasonable thing to do, then the answer is certainly yes. You can talk with and ask questions to anyone you'd like, provided you appropriately acknowledge any assistance you receive.
If you are asking whether the postdoc has an obligation to provide substantial assistance or tutoring, then the answer is quite possibly no. It's hard to give a definitive answer, since precisely what the word "postdoc" means varies between fields and departments, but you shouldn't assume supervising graduate students is a serious part of the job unless you have some confirmation that this is true in your scenario.
If your questions are genuinely interesting and thought-provoking to the postdoc, then they will probably be happy to chat with you. You may also get a good response if you ask about topics that are truly difficult to learn about elsewhere, so that the postdoc will be sympathetic. On the other hand, if you try to lighten your workload by asking the postdoc relatively routine questions so you don't have to bother looking things up, then they will probably lose patience with you.
Yes, it's definitely ok as other answers suggest; I'd like to add a few more points though:
- Remember if you receive help beyond a certain level, you have to give that person credit afterwards, either in a thank-you note in a paper/poster, or perhaps even a coauthorship. I'm not saying that to discourage you from getting help, just so you don't forget later on.
- You can sometime reciprocate by offering them help with problems they're working on, if you feel it's too much of a one-way communication.
- Try to use the opportunity of getting help on something specific to maybe get a broader perspective on your research directions from someone who's pursuing something else. You don't have to agree with what he says but these can be useful reality checks sometimes.