How do we measure distances on cosmic scales? This lecture describes
the rungs in the cosmic distance ladder from measuring the AU in our
own Solar System out into the Hubble expansion of the universe. These
distances form the basis of the measurements that let us piece together
the present, past, and future history of the expanding Universe, setting
the ... Show More
Feb 2006
Lecture 32: Space, Time, & Gravity: General Relativity
What is gravity? Newton left that question unanswered when he formulated
his inverse square law of the gravitational force, framing no hypothesis
for what agency transmits gravity, only asserting it was an action
at a distance. Einstein brought gravity into relativity by answerin ... Show More
47m 56s
Jun 2009
Telescopes that Rocked Our World
This year marks the 400th anniversary of Galileo’s use of the first telescope. On this week’s show, we reflect on how telescopes have shifted our perspective on how small we are in size, space, and time. We also discuss how they help astronomers discover new and interesting aspec ... Show More
56 m