Carl Edward Sagan (; November 9, 1934 – December 20, 1996) was an American astronomer, cosmologist, astrophysicist, astrobiologist, author, science popularizer, and science communicator in astronomy and other natural sciences. He is best known for his work as a science popularizer and communicator. His best known scientific contribution is research on extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation. Sagan assembled the first physical messages sent into space: the Pioneer plaque and the Voyager Golden Record, universal messages that could potentially be understood by any extraterrestrial intelligence that might find them. Sagan argued the now accepted hypothesis that the high surface temperatures of Venus can be attributed to and calculated using the greenhouse effect.
You may find more from Carl Sagan on Wikiquote
The skepticism of youth signals the beginning of a search for something actually worth trusting, both within one's own psyche and in the world. That's why teens, supposedly stuck in life's lost years, are often so unequivocal about what they love and what they hate, and so frustrated when they feel misunderstood. The adolescent spirit is not the spirit of the lost. It is the conviction that you are not lost — that wandering has a purpose, and that what you deserve more than anything is the freedom to walk awhile on your own path.
It is supposed to be part of the American tradition that if we want to step out of line, we step out of line. Democracy isn't falling in line behind the president. Democracy is for people to think independently, be skeptical of government, look around and try to find out what's going on. And if they find out that government is deceiving them, to speak out as loudly as they can.