How do we define life? This lecture reviews the six basic criteria
for living systems described by biologists: order, reproduction, growth and
development, energy utilization, reaction to environment, and evolution
that characterize life. The last third of the lecture is an admittedly
whirlwind review of natural selection (I got off my stride and got a
li ... Show More
Oct 2009
Lecture 10: The Earth's Atmosphere Erratum
This lecture was to be about the Earth's atmosphere, its composition and
structure, the greenhouse effect, and the primordial atmosphere, but
about 2 seconds into the lecture, unbeknownst to me, the battery
compartment on my digital voice recorder came open in my pocket. At the
e ... Show More
1m 17s
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