Up Next
Back to Show
PBS Space Time
What If The Speed of Light is Not Constant?
Season 9
Episode 19
One of the most fundamental physics facts is that the speed of light in a vacuum is constant for all observers. But can we really be sure? In fact, variable speed of light theories have long been used to try to explain everything from dark energy to gravity itself. Let’s explore how constant this fundamental constant really is.
Sign up now for inspiring and thought-provoking media delivered straight to your inbox.
Support Provided By
18:26
Learn about Nobel laureate Roger Penrose's idea of how consciousness is caused by quantum processes.
16:28
Faster than light travel may produce gravitational waves that we could see here on Earth.
20:07
All particles belong to two large groups: fermions and bosons.
16:11
Just how much stronger is this year’s solar activity going to get?
17:25
So you’ve decided to jump into a black hole...
12:51
We only recently figured out where cosmic rays are coming from.
13:28
Black hole complementarity may force us to rethink what it means to say that it exists.
20:15
To travel the stars without faster than light travel we’re going to need a generation ship.
16:19
Today we are jumping into a black hole. Again.
15:36
The Moon: humanity’s first destination beyond our atmosphere.
15:07
So how did humans figure out the solar system? Eclipses!
15:02
Is gravity just an emergent effect of entropy?