Proof: Consider one of the 17 points, for example, point A. Draw 16 line segments from point A, which can be colored in three colors. By the pigeonhole principle, there must be at least 6 line segments of the same color, let's say AB, AC, AD, AE, AF, AG are all red.

If among the six points B, C, D, E, F, G, there are two points connected by a red line, suppose these two points are B and C, then $\triangle ABC$ is a triangle with all three sides being red.

If among the six points B, C, D, E, F, G, no two points are connected by a red line, then consider the 5 line segments BC, BD, BE, BF, BG. Their colors can only be two different ones, and there must be 3 line segments of the same color, suppose BC, BD, BE are all yellow. Next, consider the colors of the three sides of $\triangle CDE$. If they are all blue, then $\triangle CDE$ is a triangle with all three sides being blue. If at least one side is yellow, suppose this side is CD, then $\triangle BCD$ is a triangle with all three sides being yellow. Therefore, there are at least three scientists who communicate with each other on the same topic, which concludes the proof with $\boxed{\text{at least three scientists communicate on the same topic}}$.