How and when will the Universe end? Gravity and dark matter are poised to annihilate the Universe in a big crunch. Expansion and dark energy may tear it apart. Or, a phase transition could kill us tomorrow in a cosmic death bubble.
Thanks to observations of galaxy redshifts, we can tell that the universe is EXPANDING! Knowing that the universe is expanding and how quickly its expanding also allows us to run the clock backwards 14 billion years to the way the universe began - with a bang.
The first episode of this series focuses on a subject that has fascinated scientists for hundreds of years - stars. Right now in the Universe's giant furnaces stars are being born. See how their creation changed the cosmos forever, leading to planets and life itself.
For many years our place in the universe was the subject of theologians and philosophers, not scientists, but in 1960 one man changed all that. Dr Frank Drake was one of the leading lights in the new science of radio astronomy when he did something that was not only revolutionary, but could have cost him his career. Working at the National Radio Astronomy Observatory in Greenback in Virginia, he pointed one of their new 25-metre radio telescopes at a star called Tau Ceti twelve light years from earth, hoping for signs of extraterrestrial intelligence.
The expanding universe is a complicated place. During inflation the universe expanded faster than light, but that's something that actually happens all the time, it's happening right now. This doesn't violate Einstein's theory of relativity since nothing is moving through space faster than light, it's just that space itself is expanding such that far away objects are receding rapidly from each other. Common sense would dictate that objects moving away from us faster than light should be invisible, but they aren't. This is because light can travel from regions of space which are superluminal relative to us into regions that are subluminal. So our observable universe is bigger than our Hubble sphere - it's limited by the particle horizon, the distance light could travel to us since the beginning of time as we know it.