Previously, I mentioned the most important means of communications of physics ideas - via publication in a peer-reviewed journal. In this posting, I will mention the other significant means of communications in physics, via presentations at various conferences, seminars, workshops, etc.
The reason why there are numerous conferences and workshops throughout the world within a year is because this is actually one of the most effective and quickest means to communicate. One can actually meet and hear the person who actually did the work. You can easily ask questions to a person, something that can't be done very well when reading a published paper. A talk or presentation also tends to be more elaborate, containing detail information that may not have been included in a paper. Not only that, due to the sometime lengthy process of publishing a paper, by the time a paper appears in print, it may already be old news. On the other hand, information gathered at a conference could be some data that was only obtained just the previous week. So one can get a good sense of the state of knowledge that everyone has, or is working on, at that instant. Relying simply on what is in publication could mean one is several months behind on what is important. This is especially true in fast-moving fields such as high-Tc superconductivity.
Personally, I find that it is vital that one attends such conferences in one's field regularly. Not only is it useful to hear various speakers present their work, but more often than not, some of the most important information is obtained in the hallways or over coffee during a conversation. The latest PRL publication that I had was an idea that was born during a coffee break conversation in between sessions at a workshop! One cannot overemphasize the importance of such face-to-face discussion. Physics is seldom done in isolation, since most of us are not Einstein or Planck.
While it isn't a formal part of the curriculum for most graduate students in physics, I know for a fact that attending and presenting one's work while still in a graduate program is a vital part of the training of becoming a physicist. One should not be satisfied that a doctorate degree in physics if one has not stood in front of experts in the field and present one's work. One's ability to communicate one's work effectively is almost as important as the knowledge itself.
There are several major conferences throughout the year. However, the largest yearly physics conference in the world is the APS March Meeting. This regularly attracts between 5000 to 7000 attendees. It is the largest because the division of Condensed Matter/Material science is one of the division that meets during this meeting. In fact, during the APS Centenial Celebration in 1999 at the Atlanta Convention Center, there was a record of 13,000 attendees, which was hailed as the largest ever gathering of scientists in the history of human civilization. The APS March Meeting is the conference that most graduate students, especially those in condensed matter/material science, cut their teeth and made their first ever presentation of their work in front of experts in their fields. Yours truly was one of those.
You may visit the APS webpage to learn more about this meeting, and all other conferences that they organize. There are also a lot of events that are also open to the general public. So if any of these meetings are in your city (they move around each year), it is a good idea to see if you can attend some of them.