Sometimes you will need to look up words or get some basic information before you are able to fully understand the articles you are reading in scientific journals. Using these encyclopedias and dictionaries can help to get your research started.
For more reliable Google results, you can limit your search to a particular site or domain.
Sites from U.S. institutions of higher education and the U.S. government tend to be more reliable than .coms and even many .orgs.
e.g. "dark energy" site:.edu
e.g. "dark energy" site:haverford.edu
e.g. "dark energy" site:.gov
e.g. "dark energy" site:nasa.gov