教育学习   

Keywords:

SEAN CARROLL: For tens of thousands of years, much of North America lay buried under ice up to a mile thick. Then the massive ice sheets receded. In what is now Alaska, ocean bound stream...

Keywords:

So the basic concept is that heat inside the Earth drives motions. We have convection currents, through which heat is dissipated from the interior of the Earth. Those convection current...

Keywords:

TYLER LYSON: Even though I've collected thousands and thousands of dinosaur bones and other fossils, every fossil that I find, it's just quite a thrill because you're the first person ...

Keywords:

Earth’s temperature is affected by a process called the greenhouse effect, which is how the atmosphere keeps our planet’s surface warm. This process begins with energy from the sun, which is m...

Keywords:

[SCHRAG:] OK. But that still doesn't really answer our question. It doesn't really explain how did Venus this get this way, why is Mars this way, and why has the Earth persisted in this...

Keywords:

SEAN CARROLL: For life to survive, it must adapt and re-adapt to an ever-changing Earth. New traits and capabilities must be invented, while some traits may be lost. [SNAKE HISSING] ...

Keywords:

SPENCER WELLS: Only a small number of human beings live like this today. But from the time our species evolved some 200,000 years ago until the not-too-distant past, all of us lived as ...

Keywords:

JOHN SHEA: Those are nice principles. But let me give you a demonstration of this. Imagine if you will, that this is a depositive sediment. So this little ant farm-like deposit is an a...