What are the first recognizable forms of life that we find in the
geological record? How far back can we go in geological time and still
find life? This lecture reviews three lines of evidence that have
emerged in recent years to suggest that life may have emerged very early
on the young Earth, perhaps within a few hundred million years of the
end of the ... Show More
Oct 2009
Lecture 17: Life on the Edge
Extremophiles are organisms that are adapted to survive in extreme environments. This lecture describes the challenges that
extremes of heat, cold, acidity, salinity, and radiation pose to
organisms, and show examples of how evolution has nonetheless allowed
some organisms to ada ... Show More
46m 54s
Oct 2009
Lecture 15: The Chemistry of Life
What is the basic chemistry of living organisms? We introduce the requirements for metabolism (raw
materials and energy), the ATP/ADP energy cycle in cells, auto- and
heterotrophs, photosynthesis and chemosynthesis, and the role played by
liquid water. The goal of today's lecture ... Show More
45m 4s
Mar 2022
Comment calculer l'âge d'une étoile ?
La durée de vie d'une étoile peut nous renseigner sur sa composition et sur l'existence éventuelle de la vie dans le cosmos. mais, en dehors du Soleil, il est assez difficile de déterminer l'âge d'une étoile.
L'importance de la masse
En évaluant, grâce à la radioactivité, l'âge d ... Show More
1m 58s