Our observable universe shines with the light of hundreds of billions of galaxies, each with hundreds of billions of stars, vast clouds of gas and dust, nebula cast off in explosions — a zoo of luminous objects. And while that might sound like a lot of stuff, everything we have ever seen constitutes less than 5% of what’s out there. Nearly 25% of the universe’s content hides in an unknown form: Dark Matter. Despite decades of effort to detect dark matter, the substance eludes us.

Janna Levin, astrophysicist and writer, invites physicists Elena Aprile of Columbia and Peter Fisher of MIT to ask if we truly should look for a new fundamental constituent of nature, or could dark matter actually be microscopic black holes?

Scientific Controversies<br />
No. 9: Dark Matter


<p>Our observable universe shines with the light of hundreds of billions of galaxies, each with hundreds of billions of stars, vast clouds of gas and dust, nebula cast off in explosions — a zoo of luminous objects. And while that might sound like a lot of stuff, everything we have ever seen constitutes less than 5% of what’s out there. Nearly 25% of the universe’s content hides in an unknown form: Dark Matter. Despite decades of effort to detect dark matter, the substance eludes us.</p>
<p>Janna Levin, astrophysicist and writer, invites physicists Elena Aprile of Columbia and Peter Fisher of MIT to ask if we truly should look for a new fundamental constituent of nature, or could dark matter actually be microscopic black holes?</p>
<h3>With Guests</h3>
<p><strong>Elena Aprile</strong><br />
Physicist, Columbia University.</p>
<p><strong>Peter Fisher</strong><br />
Physicist, MIT.</p>


No. 9<br />
Dark Matter

<div>Are there Many Worlds? Does Time Exist? Are We Alone?  Hosted by Director of Sciences <a href="http://jannalevin.com/">Janna Levin</a>, the Scientific Controversies series  brings creative minds together to celebrate the passionate spirit of scientific curiosity.  Previous guests include Nobel Laureate Frank Wilczek, geneticist George Church, and neuroscientist Christof Koch with subjects ranging from artificial intelligence and string theory, to dark matter, consciousness, and other unsolved scientific quandaries.</div>